All-solid-state secondary battery

Abstract

The present invention provides an all-solid-state secondary battery. The all-solid-state secondary battery comprises: a positive electrode layer; a negative electrode layer; and a solid electrolyte layer provided between the positive electrode layer and the negative electrode layer, in which the positive electrode layer includes a positive electrode current collector and a positive electrode active material layer provided on one or both surfaces of the positive electrode current collector, the positive electrode active material layer containing a positive electrode active material, the negative electrode layer includes a negative electrode current collector and a first negative electrode active material layer disposed on one surface of the negative electrode current collector, and the negative electrode layer includes a first non-active member disposed on one side surface of the negative electrode layer. Disclosed is an all-solid-state secondary battery including: a positive electrode layer; a negative electrode layer; and a solid electrolyte layer provided between the positive electrode layer and the negative electrode layer, in which the positive electrode layer includes a positive electrode current collector and a positive electrode active material layer provided on one or both surfaces of the positive electrode current collector, the positive electrode active material layer containing a lithium-containing sulfide-based positive electrode active material, the lithium-containing sulfide positive electrode active material comprises Li2S, a Li2S-containing compound or a combination thereof, the negative electrode layer comprises a negative electrode current collector and a lithium main body layer arranged on one surface of the negative electrode current collector, the lithium main body layer comprises a lithium main body structure, and the lithium main body structure comprises at least one lithium main body. The lithium body includes a carbon-based lithium body, a metal-based lithium body, a polymer-based lithium body, or a combination thereof, and the negative electrode layer includes a first non-active member on one side surface of the negative electrode layer.

Description

Technical Field

[0001] The present disclosure relates to all-solid-state secondary batteries. Background Art

[0002] Recently, batteries that provide increased energy density and safety have been actively developed. Lithium batteries are used in information devices, communication devices, vehicles, etc. Since vehicles affect human lives, their safety is important.

[0003] Lithium batteries including liquid electrolytes include flammable organic solvents. Lithium batteries including liquid electrolytes have a high risk of overheating and catching fire in the case of a short circuit.

[0004] Compared with liquid electrolytes, solid electrolytes have a reduced possibility of overheating and catching fire in the case of a short circuit. Compared with lithium batteries including liquid electrolytes, lithium batteries including solid electrolytes can provide improved safety. Summary of the Invention

[0005] Technical Problem

[0006] In a secondary battery including lithium metal, a short circuit may occur between the lithium metal and the positive electrode due to the growth of lithium dendrites and / or the elution of molten lithium during the charge / discharge process. There is a need for a secondary battery that can effectively prevent such a short circuit between the lithium dendrites and / or the lithium metal and the positive electrode during the charge / discharge process of the secondary battery.

[0007] During the manufacturing process and / or the charge / discharge process of the secondary battery, defects occur in the solid electrolyte layer, and due to these defects, cracks appear and grow in the solid electrolyte layer. A short circuit occurs when lithium grows through these cracks. There is a need for a secondary battery that can suppress the occurrence of such defects during the manufacturing process and / or the charge / discharge process of the secondary battery.

[0008] One aspect is to provide a secondary battery having a novel structure that prevents a short circuit between the negative electrode and the positive electrode due to lithium dendrites, etc., and suppresses the occurrence of defects in the secondary battery during manufacturing and / or charge / discharge.

[0009] In a secondary battery, a sulfur-based material (e.g., S) is used as a positive electrode active material to increase the capacity. When manufacturing a secondary battery including a sulfur-based material (e.g., S), since lithium is not included in the positive electrode, lithium metal is used for the negative electrode. During the initial discharge process of the secondary battery, the lithium metal moves to the positive electrode including the sulfur-based material, and then during the subsequent charging process, the lithium metal precipitates again between the negative electrode current collector and the electrolyte layer. During the lithium precipitation process, due to irregular lithium precipitation, lithium dendrites and / or dead lithium are likely to form. Due to the formation of such lithium dendrites and / or dead lithium, the reversibility of the electrode reaction may be reduced. A method for suppressing the non-uniform precipitation of lithium precipitated on the positive electrode is needed.

[0010] In a secondary battery including lithium metal, a short circuit may occur between the lithium metal and the positive electrode due to the growth of lithium dendrites formed during the charge or discharge process and / or the elution of molten lithium. A secondary battery capable of effectively preventing such a short circuit between the lithium dendrites and / or the lithium metal and the positive electrode during the charge / discharge process of the secondary battery is needed.

[0011] In a secondary battery including lithium metal, the deterioration of the secondary battery may be accelerated due to a significant change in the thickness of the negative electrode caused by the precipitation and dissolution of the lithium metal layer during charge / discharge. A secondary battery capable of suppressing such a significant change in the volume of the negative electrode (such as a change in thickness) during the charge / discharge process of the secondary battery is needed.

[0012] One aspect is to provide a secondary battery having a novel structure capable of suppressing the non-uniform precipitation of lithium at the negative electrode layer during charge / discharge, preventing a short circuit between the negative electrode and the positive electrode due to lithium dendrites or the like, preventing a rapid change in the volume of the negative electrode layer, and suppressing the occurrence of defects in the secondary battery during manufacturing and / or charge / discharge.

[0013] Solution to the problem

[0014] According to an embodiment,

[0015] A all-solid-state secondary battery is provided, which includes a positive electrode layer, a negative electrode layer, and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer,

[0016] wherein the positive electrode layer includes a positive electrode current collector and a positive electrode active material layer disposed on one or both sides of the positive electrode current collector,

[0017] the positive electrode active material layer includes a positive electrode active material, the negative electrode layer includes a negative electrode current collector and a first negative electrode active material layer disposed on one side of the negative electrode current collector, and

[0018] the all-solid-state secondary battery further includes a first inactive member disposed on the side surface of the negative electrode layer.

[0019] According to another embodiment,

[0020] There is provided an all-solid-state secondary battery including a positive electrode layer, a negative electrode layer, and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer,

[0021] wherein the positive electrode layer includes a positive electrode current collector and a positive electrode active material layer disposed on one or both sides of the positive electrode current collector,

[0022] the positive electrode active material layer includes a lithium-containing sulfide-based positive electrode active material, and the lithium-containing sulfide-based positive electrode active material includes Li2S, a Li2S-containing composite, or a combination thereof,

[0023] the negative electrode layer includes a negative electrode current collector and a lithium host layer disposed on one side of the negative electrode current collector,

[0024] the lithium host layer includes a lithium host structure,

[0025] the lithium host structure includes one or more lithium hosts, and the lithium host includes a carbon-based lithium host, a metal-based lithium host, a polymer-based lithium host, or a combination thereof, and

[0026] the all-solid-state secondary battery further includes a first inactive member disposed on a side surface of the negative electrode layer.

[0027] According to another embodiment,

[0028] There is provided an all-solid-state secondary battery including a positive electrode layer, a negative electrode layer, and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer,

[0029] wherein the positive electrode layer includes a positive electrode current collector and a positive electrode active material layer disposed on one or both sides of the positive electrode current collector,

[0030] the positive electrode active material layer includes a lithium-containing sulfide-based positive electrode active material, and the lithium-containing sulfide-based positive electrode active material includes Li2S, a Li2S-containing composite, or a combination thereof,

[0031] the negative electrode layer includes a negative electrode current collector and a lithium host layer disposed on one side of the negative electrode current collector,

[0032] the lithium host layer includes a lithium host structure,

[0033] the lithium host structure includes one or more lithium hosts, and the lithium host includes a carbon-based lithium host, a metal-based lithium host, a polymer-based lithium host, or a combination thereof.

[0034] According to another embodiment,

[0035] Provided is a all-solid-state secondary battery, which includes a positive electrode layer, a negative electrode layer, and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer.

[0036] Among them, the positive electrode layer includes a positive electrode current collector and a positive electrode active material layer disposed on one or both sides of the positive electrode current collector.

[0037] The positive electrode active material layer includes a positive electrode active material.

[0038] The negative electrode layer includes a negative electrode current collector and a lithium host layer disposed on one side of the negative electrode current collector.

[0039] The lithium host layer includes a lithium host structure.

[0040] The lithium host structure includes one or more lithium hosts, and the lithium host includes a carbon-based lithium host, a metal-based lithium host, a polymer-based lithium host, or a combination thereof.

[0041] Advantageous Effects of the Invention

[0042] According to one aspect, based on the all-solid-state secondary battery with a novel structure, an all-solid-state secondary battery with suppressed short circuit and improved cycling characteristics can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 is a cross-sectional view of an all-solid-state secondary battery according to an exemplary embodiment.

[0044] Figure 2 is a cross-sectional view of an all-solid-state secondary battery according to an exemplary embodiment.

[0045] Figure 3 is a cross-sectional view of a dual-cell all-solid-state secondary battery according to an exemplary embodiment.

[0046] Figure 4 is a schematic view of the negative electrode layer of an all-solid-state secondary battery according to an exemplary embodiment.

[0047] Figure 5 is a schematic view partially showing the inside of an all-solid-state secondary battery according to an exemplary embodiment.

[0048] Figure 6 is a cross-sectional view of an all-solid-state secondary battery according to an exemplary embodiment.

[0049] Figure 7 is a cross-sectional view of an all-solid-state secondary battery according to an exemplary embodiment.

[0050] Figure 8 is a cross-sectional view of a dual-cell all-solid-state secondary battery according to an exemplary embodiment.

[0051] Figure 9A cross-sectional view of a stacked dual-cell all-solid-state secondary battery according to an exemplary embodiment.

[0052] Figure 10 A cross-sectional view of an all-solid-state secondary battery according to an exemplary embodiment.

[0053] Figure 11 A cross-sectional view of an all-solid-state secondary battery according to an exemplary embodiment.

[0054] Figure 12 A cross-sectional view of an all-solid-state secondary battery according to an exemplary embodiment.

[0055] Figure 13 A cross-sectional view of an all-solid-state secondary battery according to an exemplary embodiment.

[0056] Figure 14 A cross-sectional view of a dual-cell all-solid-state secondary battery according to an exemplary embodiment.

[0057] Figure 15 A cross-sectional view of a dual-cell all-solid-state secondary battery according to an exemplary embodiment.

[0058] Figure 16 A schematic view of an all-solid-state secondary battery according to an exemplary embodiment.

[0059] Figure 17 A schematic view partially showing the interior of an all-solid-state secondary battery according to an exemplary embodiment. Detailed Description

[0060] Various embodiments are shown in the drawings. However, the inventive concept may be implemented in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the inventive concept to those skilled in the art. Like reference numerals denote like elements.

[0061] When describing an element "on" another element, it will be understood that the element may be directly disposed on the other element, or another element may be interposed therebetween. On the other hand, when describing an element "directly on" another element, no other element is interposed therebetween.

[0062] It will be understood that although the terms "first", "second", and "third" may be used herein to describe various elements, components, regions, layers, and / or sections, these elements, components, regions, layers, and / or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer, or section from another element, component, region, layer, or section. Thus, a first element, component, region, layer, or section described below may be termed a second element, component, region, layer, or section without departing from the teachings of this specification.

[0063] The terms used herein are only intended to describe particular embodiments and are not intended to limit the inventive concept. As used herein, unless the context clearly dictates otherwise, the singular forms "a", "an", and "the" are intended to include the plural forms including "at least one". "At least one" should not be construed as being limited to the singular. As used herein, the term "and / or" includes any combination and all combinations of one or more of the associated listed items. When used in the detailed description, the terms "comprises", "comprising", and / or their variants specify the presence of the stated features, regions, wholes, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, regions, wholes, steps, operations, elements, components, and / or groups thereof.

[0064] Spatial relative terms such as "beneath", "below", "under", "above", and "on" may be used herein to simply describe the relationship of one element or feature to another element or feature. It will be understood that the spatial relative terms are intended to cover different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, when the device in the figures is turned over, an element described as "beneath" or "under" another element or feature will then be "above" or "on" the other element or feature. Thus, the exemplary term "beneath" can cover both an upper and a lower orientation. The device may be otherwise positioned (rotated 90 degrees or at other orientations), and the spatial relative terms used herein may be interpreted accordingly.

[0065] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. Additionally, it will be understood that terms (such as those defined in a general dictionary) should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and this disclosure, and will not be interpreted in an idealized or overly formal sense unless so defined herein.

[0066] Exemplary embodiments are described herein with reference to cross-sectional views that are schematic illustrations of idealized embodiments. As such, variations in the shapes of the illustrations due to, for example, manufacturing techniques and / or tolerances are to be expected. Accordingly, the embodiments described herein should not be construed as being limited to the particular shaped regions shown herein, but may include shape deviations resulting from, for example, manufacturing. For example, regions shown or described as flat may generally be rough and / or have non-linear features. Additionally, sharp corners may be rounded. Thus, the regions shown in the figures are schematic in nature, and their shapes are not intended to depict the actual shape of the regions and are not intended to limit the scope of the claims.

[0067] "Group" refers to a group of the periodic table according to the International Union of Pure and Applied Chemistry ("IUPAC") group classification system from Group 1 to Group 18.

[0068] As used herein, the term "particle size" refers to the average diameter when the particle is spherical and refers to the average major axis length when the particle is non-spherical. The particle size can be measured using a particle size analyzer (PSA). "Particle size" is, for example, the average particle size. "Average particle size" refers to, for example, the median particle size (D50).

[0069] D50 refers to the particle size corresponding to 50% cumulative volume when calculating the particle size distribution measured by the laser diffraction method starting from particles with a smaller particle size.

[0070] D90 refers to the particle size corresponding to 90% cumulative volume when calculating the particle size distribution measured by the laser diffraction method starting from particles with a smaller particle size.

[0071] D10 refers to the particle size corresponding to 10% cumulative volume when calculating the particle size distribution measured by the laser diffraction method starting from particles with a smaller particle size.

[0072] The term "metal" as used herein includes all of metals and metalloids (such as silicon and germanium in elemental or ionic states).

[0073] The term "alloy" as used herein refers to a mixture of two or more metals.

[0074] The term "electrode active material" as used herein refers to an electrode material that can undergo lithiation and delithiation.

[0075] The term "positive electrode active material" as used herein refers to a positive electrode material that can undergo lithiation and delithiation.

[0076] The term "negative electrode active material" as used herein refers to a negative electrode material that can undergo lithiation and delithiation.

[0077] The term "lithiation" and its variants as used herein refer to the process of adding lithium to an electrode active material.

[0078] As used herein, the term "delithiation" and variations thereof refer to a process of removing lithium from an electrode active material.

[0079] In the present disclosure, the term "lithium host" refers to a substrate or framework that accommodates lithium in an electrochemically preformed space.

[0080] In the present disclosure, the term "lithium host structure" refers to a structure composed of one or more lithium hosts.

[0081] As used herein, the term "charging" and variations thereof refer to a process of providing electrochemical energy to a battery.

[0082] As used herein, the term "discharging" and variations thereof refer to a process of removing electrochemical energy from a battery.

[0083] As used herein, the terms "positive electrode" and "cathode" refer to the electrode where electrochemical reduction and lithiation occur during the discharging process.

[0084] As used herein, the terms "negative electrode" and "anode" refer to the electrode where electrochemical oxidation and delithiation occur during the discharging process.

[0085] Although specific embodiments have been described, alternatives, modifications, variations, improvements, and substantial equivalents that are currently unforeseen or may be unforeseen at present can be conceived by the applicant or those skilled in the art. Therefore, the appended claims, as filed and as may be amended, are intended to cover all such alternatives, modifications, variations, improvements, and substantial equivalents.

[0086] Hereinafter, a all-solid-state secondary battery according to an embodiment will be described in more detail.

[0087] [All-Solid-State Secondary Battery]

[0088] The all-solid-state secondary battery according to an embodiment includes a positive electrode layer, a negative electrode layer, and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer. The positive electrode layer includes a positive electrode current collector and a positive electrode active material layer disposed on one or both sides of the positive electrode current collector. The positive electrode active material layer includes a positive electrode active material. The negative electrode layer includes a negative electrode current collector and a first negative electrode active material layer disposed on one side of the negative electrode current collector. And the all-solid-state secondary battery includes a first inactive member disposed on a side surface of the negative electrode layer.

[0089] The inactive member is disposed on the side surface of the negative electrode layer, so as to more effectively suppress a short circuit between the positive electrode and lithium dendrites generated and grown during charging / discharging of the all-solid-state secondary battery and / or lithium metal melted at high temperature. Thereby, a short circuit of the all-solid-state secondary battery is prevented, and its life characteristics are improved.

[0090] An inactive member is additionally provided on the side surface of the positive electrode layer, thereby suppressing defects occurring in the solid electrolyte layer during the manufacturing process and / or charge / discharge process of the all-solid-state secondary battery. Accordingly, short circuit and life reduction of the all-solid-state secondary battery due to the growth of such defects can be prevented. Thereby, the cycle characteristics of the all-solid-state secondary battery are improved.

[0091] Refer to Figures 1 to 9 , the all-solid-state secondary battery 1 includes a positive electrode layer 10, a negative electrode layer 20, and a solid electrolyte layer 30 disposed between the positive electrode layer 10 and the negative electrode layer 20. Among them, the positive electrode layer 10 includes a positive electrode current collector 11 and a positive electrode active material layer 12 disposed on one or both sides of the positive electrode current collector. The positive electrode active material layer 12 includes a positive electrode active material. The negative electrode layer 20 includes a negative electrode current collector 21 and a first negative electrode active material layer 22 disposed on one side of the negative electrode current collector. And the all-solid-state secondary battery 1 includes a first inactive member 42 disposed on the side surface of the negative electrode layer 20.

[0092] [Negative electrode layer]

[0093] [Negative electrode layer: First inactive member]

[0094] Refer to Figures 1 to 9 , the negative electrode layer 20 includes a negative electrode current collector 21 and a first negative electrode active material layer 22 disposed on one side of the negative electrode current collector. The first inactive member 42 is disposed on the side surface of the negative electrode layer 20. The first inactive member 42 is disposed on the side surface of each of the first negative electrode active material layer 22 and the negative electrode current collector 21. Since the all-solid-state secondary battery 1 includes the first inactive member 42 on the side surface of the negative electrode layer 20, short circuit between the positive electrode and lithium dendrites generated and grown during charge / discharge of the all-solid-state secondary battery 1 and / or lithium metal melted at high temperature is more effectively suppressed.

[0095] In the all-solid-state secondary battery 1, the thickness T2 of the first inactive member 42 is greater than or equal to the thickness T1 of the first negative electrode active material layer 22. In the all-solid-state secondary battery 1, the thickness T2 of the first inactive member 42 is substantially equal to the thickness T3 of the negative electrode layer 20. Since the thickness T2 of the first inactive member 42 is equal to the thickness T3 of the negative electrode layer 20, uniform pressure is applied between the negative electrode layer 20 and the solid electrolyte layer 30, and the negative electrode layer 20 and the solid electrolyte layer 30 are in sufficient close contact with each other, thereby reducing the interfacial resistance between the negative electrode layer 20 and the solid electrolyte layer 30. In addition, during the process of pressing and manufacturing the all-solid-state secondary battery 1, the solid electrolyte layer 30 is sufficiently sintered, thereby reducing the internal resistance of the solid electrolyte layer 30 and the all-solid-state secondary battery 1 including the same.

[0096] The first inactive member 42 surrounds the side surface of the negative electrode layer 20 and contacts the solid electrolyte layer 30. The first inactive member 42 surrounds the side surface of the negative electrode layer 20 and contacts the solid electrolyte layer 30, thereby effectively suppressing cracks in the solid electrolyte layer 30 that are caused by a pressure difference during the pressing process in a portion of the solid electrolyte layer 30 that does not contact the negative electrode layer 20. The first inactive member 42 surrounds the side surface of the negative electrode layer 20 and is separated from the positive electrode layer 10. The first inactive member 42 surrounds the side surface of the negative electrode layer 20, contacts the solid electrolyte layer 30, and is separated from the positive electrode layer 10. The possibility of short circuit due to physical contact between the negative electrode layer 20 and the positive electrode active material layer 12 or due to overcharging of lithium is suppressed. For example, the first inactive member 42 is disposed on the side surface of the first negative electrode active material layer 22 and also on the side surface of the negative electrode current collector 21, thereby more effectively suppressing the possibility of short circuit due to contact between the negative electrode current collector 21 and the positive electrode layer 10.

[0097] Referring to Figure 1 , Figures 3 to 6 and Figures 8 to 9 , the first inactive member 42 (42a or 42b) extends from the side surface of the negative electrode layer 20 to the end of the solid electrolyte layer 30. The first inactive member 42 extends to the end of the solid electrolyte layer 30, thereby suppressing the generation of cracks at the end of the solid electrolyte layer 30. The end of the solid electrolyte layer 30 may be the outermost portion that contacts the side surface of the solid electrolyte layer 30. The first inactive member 42 (42a or 42b) extends to the outermost portion that contacts the side surface of the solid electrolyte layer 30. The first inactive member 42 (42a or 42b) is separated from the positive electrode layer 10 (more specifically, the positive electrode active material layer 12). The first inactive member 42 (42a or 42b) extends to the end of the solid electrolyte layer 30 but does not contact the positive electrode layer 10. The first inactive member 42 (42a or 42b) fills, for example, the space extending from the side surface of the negative electrode layer 20 to the end of the solid electrolyte layer 30.

[0098] Referring to Figure 1, the width W2 of the first inactive member 42 extending from the side surface of the negative electrode layer 20 to the end portion of the solid electrolyte layer 30 is, for example, in the range of 1% to 20%, 1% to 15%, 1% to 10%, or 1% to 5% of the width W1 between one side of the negative electrode layer 20 and the other side opposite to the one side. When the width W2 of the first inactive member 42 is too wide, the energy density of the all-solid-state secondary battery 1 decreases. When the width W2 of the first inactive member 42 is too narrow, the effect of arranging the first inactive member 42 is not significant. The area S1 of the negative electrode layer 20 is smaller than the area S3 of the solid electrolyte layer 30 in contact with the negative electrode layer 20. The first inactive member 42 is arranged to surround the side surface of the negative electrode layer 20 to compensate for the difference in area between the negative electrode layer 20 and the solid electrolyte layer 30. The area S2 of the first inactive member 42 compensates for the difference between the area S1 of the negative electrode layer 20 and the area S3 of the solid electrolyte layer 30, thereby effectively suppressing cracks in the solid electrolyte layer 30 caused by the pressure difference during the pressing process. For example, the sum of the area S1 of the negative electrode layer 20 and the area S2 of the first inactive member 42 is equal to the area S3 of the solid electrolyte layer 30. The area S1 of the negative electrode layer 20 is, for example, 100% or less, 99% or less, 98% or less, 97% or less, 96% or less, or 95% or less of the area S3 of the solid electrolyte layer 30. The area S1 of the negative electrode layer 20 is, for example, in the range of 70% to less than 100%, 70% to 99%, 75% to 98%, 80% to 97%, 80% to 96%, or 85% to 95% of the area S3 of the solid electrolyte layer 30. The area S2 of the first inactive member 42 is, for example, 50% or less, 40% or less, 30% or less, 20% or less, or 10% or less of the area S1 of the negative electrode layer 20. The area S2 of the first inactive member 42 is, for example, in the range of 1% to 50%, 5% to 40%, 5% to 30%, 5% to 20%, or 5% to 15% of the area S1 of the negative electrode layer 20. The area S1 of the negative electrode layer 20 is larger than the area S5 of the positive electrode current collector 11. The area S1 of the negative electrode layer 20 is, for example, more than 100%, 101% or more, 102% or more, 103% or more, 104% or more, or 105% or more of the area S5 of the positive electrode current collector 11. The area S1 of the negative electrode layer 20 is, for example, in the range of more than 100% to 120%, more than 100% to 110%, or more than 100% to 105% of the area S5 of the positive electrode current collector 11. The area S5 of the positive electrode current collector 11 is, for example, equal to the area of the positive electrode layer 10.

[0099] Refer to Figure 2, the area S'1 of the negative electrode layer 20 is equal to the area S'3 of the solid electrolyte layer 30 in contact with the negative electrode layer 20. The first inactive member 42 is disposed to surround the side surface of the negative electrode layer 20, and the first inactive member 42 extends to be disposed on at least a part of the side surface of the solid electrolyte layer 30. The first inactive member 42 surrounds both the side surface of the negative electrode layer 20 and the side surface of the solid electrolyte layer 30, thereby more effectively preventing a short circuit between the first negative electrode active material layer 22 and the positive electrode layer 10 caused by the growth of lithium dendrites precipitated during the charge / discharge process and / or the elution of lithium. The area S'2 of the first inactive member 42 is, for example, 50% or less, 40% or less, 30% or less, 20% or less, or 10% or less of the area S'1 of the negative electrode layer 20. The area S'2 of the first inactive member 42 is, for example, in the range of 1% to 50%, 5% to 40%, 5% to 30%, 5% to 20%, or 5% to 15% of the area S'1 of the negative electrode layer 20. The area S'5 of the positive electrode current collector 11 is, for example, equal to the area of the first negative electrode active material layer 22.

[0100] In this specification, "equal" areas, lengths, widths, thicknesses, and / or shapes may include all cases having "substantially equal" areas, lengths, widths, thicknesses, and / or shapes, excluding cases where the areas, lengths, widths, thicknesses, and / or shapes are intentionally different from each other. "Equal" areas, lengths, widths, and / or thicknesses include cases where the unintended differences in the areas, lengths, widths, and / or thicknesses between the objects being compared are, for example, in the range of less than 1%, less than 0.5%, or less than 0.1%.

[0101] The thickness of the first inactive member 42 is, for example, greater than the thickness of the first negative electrode active material layer 22. The thickness of the first negative electrode active material layer 22 is, for example, 50% or less, 40% or less, 30% or less, 20% or less, 10% or less of the thickness of the first inactive member 42. The thickness of the first negative electrode active material layer 22 is, for example, in the range of 1% to 50%, 1% to 40%, 1% to 30%, 1% to 20%, or 1% to 10% of the thickness of the first inactive member 42. Since the first inactive member 42 has a thickness within this range, the elution of the lithium metal layer precipitated between the first negative electrode active material layer 22 and the negative electrode current collector 21 can be more effectively prevented.

[0102] The thickness of the solid electrolyte layer 30 is, for example, greater than the thickness of the first negative electrode active material layer 22. The thickness of the first negative electrode active material layer 22 is, for example, 50% or less, 40% or less, 30% or less, 20% or less, or 10% or less of the thickness of the solid electrolyte layer 30. The thickness of the first negative electrode active material layer 22 is, for example, in the range of 1% to 50%, 1% to 40%, 1% to 30%, 1% to 20%, or 1% to 10% of the thickness of the solid electrolyte layer 30. Since the solid electrolyte layer 30 has a thickness within such a range, the all-solid-state secondary battery 1 can be given structural stability and the energy density of the all-solid-state secondary battery 1 can also be prevented from decreasing.

[0103] The area S1 of the negative electrode layer 20 is, for example, larger than the area of the positive electrode layer 10. The area S1 of the negative electrode layer 20 is, for example, in the range of more than 100% to 150%, more than 100% to 130%, more than 100% to 110%, or more than 100% to 105% of the area of the positive electrode layer 10. In the thickness direction of the all-solid-state secondary battery 1, the outer boundary of the positive electrode layer 10 may be included within the outer boundary of the negative electrode layer 20. Since the area S1 of the negative electrode layer 20 is larger than the area of the positive electrode layer, deterioration of the all-solid-state secondary battery 1 caused by precipitation of lithium dendrites around the negative electrode layer 20 and the like can be more effectively prevented.

[0104] The negative electrode layer 20 includes a negative electrode current collector 21 and a first negative electrode active material layer 22 provided on one side of the negative electrode current collector 21. For example, there is no first negative electrode active material layer 22 on the other side opposite to one side of the negative electrode current collector 21. For example, the first negative electrode active material layer 22 is provided only on one side of the negative electrode current collector 21 and not on the other side thereof.

[0105] The first inactive member 42 can be a washer. By using a washer as the first inactive member 42, cracks in the solid electrolyte layer 30 caused by a pressure difference during the pressing process can be effectively suppressed. In addition, elution of lithium metal precipitated during the charge / discharge process of the all-solid-state secondary battery 1 and the like can be more effectively suppressed.

[0106] The first non-active member 42 has, for example, a single-layer structure. Optionally, although not shown in the drawings, the first non-active member 42 may have a multi-layer structure. In the first non-active member 42 having a multi-layer structure, each layer may have a different composition. The first non-active member 42 having a multi-layer structure may have, for example, a two-layer structure, a three-layer structure, a four-layer structure, or a five-layer structure. The first non-active member 42 having a multi-layer structure may include, for example, one or more adhesive layers and one or more support layers. For example, the adhesive layer effectively prevents the separation between the negative electrode layer 20 and the solid electrolyte layer 30 due to the volume change of the negative electrode layer 20 that occurs during the charge / discharge process of the all-solid-state secondary battery 1, and provides the bonding force between the support layer and other layers to improve the film strength of the first non-active member 42. The support layer provides a supporting force for the first non-active member 42, prevents the non-uniformity of the pressure applied to the solid electrolyte layer 30 during the pressing process or the charge / discharge process, and prevents the shape deformation of the all-solid-state secondary battery 1 to be manufactured.

[0107] Refer to Figure 3, the all-solid-state secondary battery 1 includes a positive electrode layer 10, a negative electrode layer 20, and a solid electrolyte layer 30 disposed between the positive electrode layer 10 and the negative electrode layer 20. Among them, each of the positive electrode layer 10 includes a first positive electrode active material layer 12a and a second positive electrode active material layer 12b disposed on both sides of the positive electrode current collector 11. Each of the solid electrolyte layers 30 includes a first solid electrolyte layer 30a in contact with the first positive electrode active material layer 12a and a second solid electrolyte layer 30b in contact with the second positive electrode active material layer 12b. Each of the negative electrode layers 20 includes a first negative electrode layer 20a in contact with the first solid electrolyte layer 30a and a second negative electrode layer 20b in contact with the second solid electrolyte layer 30b. And the first inactive member 42 includes a 1a inactive member 42a disposed on the side surface of the first negative electrode layer 20a and a 1b inactive member 42b disposed on the side surface of the second negative electrode layer 20b. In addition, between the first solid electrolyte layer 30a and the second solid electrolyte layer 30b that face each other, the second inactive member 41 is disposed to surround the side surface of the positive electrode layer 10. The second inactive member 41 includes, for example, a 2a inactive member 41a in contact with the first solid electrolyte layer 30a and a 2b inactive member 41b in contact with the second solid electrolyte layer 30b. Therefore, the all-solid-state secondary battery 1 has a dual-cell structure. The all-solid-state secondary battery 1 has such a dual-cell structure, so the solid electrolyte layer 30 and the negative electrode layer 20 are symmetrically disposed relative to the positive electrode layer 10 and face each other, thereby more effectively suppressing structural deformation and the like caused by the pressure applied during the manufacture of the all-solid-state secondary battery 1. Therefore, cracks in the solid electrolyte layer 30 are suppressed during the manufacturing process and / or charge / discharge process of the all-solid-state secondary battery 1, thus preventing short circuits in the all-solid-state secondary battery 1, and further improving the cycle characteristics of the all-solid-state secondary battery 1. In addition, since only one positive electrode current collector 11 is used for the plurality of positive electrode active material layers 12a, 12b, the energy density of the all-solid-state secondary battery 1 is increased.

[0108] Although not shown in the drawings, part or all of the first inactive member 42 (42a or 42b) may be provided to be spaced apart from the side surface of the negative electrode layer 20. Part or all of the first inactive member 42 (42a or 42b) may be provided to be spaced apart from the side surface of the negative electrode layer 20, so that the manufacturing process of the all-solid-state secondary battery 1 can be made easier, and the manufacturing speed of the all-solid-state secondary battery 1 can be increased. Part or all of the first inactive member 42 (42a or 42b) may be provided to be spaced apart from the side surface of the negative electrode layer 20, and thus the volume change toward the side surface of the negative electrode layer 20 during charging or discharging can be more effectively accommodated, thereby further improving the life characteristics of the all-solid-state secondary battery 1. The distance between the first inactive member 42 (42a or 42b) and the side surface of the negative electrode layer 20 is, for example, in the range of 0.1 μm to 10 mm, 1 μm to 1 mm, 1 μm to 500 μm, 1 μm to 100 μm, 1 μm to 50 μm, or 1 μm to 10 μm. For example, the first inactive member 42 (42a or 42b) may be a gasket, and part or all of the gasket may be provided to be spaced apart from the side surface of the negative electrode layer 20 and may surround the negative electrode layer 20.

[0109] Referring to Figures 1 to 5 , the first inactive member 42 is, for example, a flame-retardant inactive member. The flame-retardant inactive member can provide flame retardancy to prevent the possibility of thermal runaway and ignition of the all-solid-state secondary battery 1. Thereby, the safety of the all-solid-state secondary battery 1 is further improved. The flame-retardant inactive member absorbs the residual moisture in the all-solid-state secondary battery 1, thereby preventing the deterioration of the all-solid-state secondary battery 1 and improving the life characteristics of the all-solid-state secondary battery 1.

[0110] The flame-retardant non-active component includes, for example, a matrix and a filler. The matrix includes, for example, a substrate and a reinforcing material. The matrix includes, for example, a fibrous substrate and a fibrous reinforcing material. The matrix may include a substrate to have elasticity. Thus, the matrix can effectively accommodate the volume change of the all-solid-state secondary battery 1 during charge / discharge and can be disposed at any one of various positions. The substrate included in the matrix includes, for example, a first fibrous material. Since the substrate includes the first fibrous material, the substrate can effectively accommodate the volume change of the negative electrode layer 20 that occurs during the charge / discharge process of the all-solid-state secondary battery 1 and can effectively suppress the deformation of the first non-active component 42 caused by the volume change of the negative electrode layer 20. The first fibrous material is, for example, a material having an aspect ratio of 5 or greater, 20 or greater, or 50 or greater. The first fibrous material is, for example, a material having an aspect ratio of 5 to 1000, 20 to 1000, or 50 to 1000. The first fibrous material is, for example, an insulating material. The first fibrous material may be an insulating material so as to effectively prevent a short circuit between the positive electrode layer 10 and the negative electrode layer 20 that occurs due to lithium dendrites or the like during the charge / discharge of the all-solid-state secondary battery 1. The first fibrous material includes, for example, at least one selected from pulp fibers, insulating polymer fibers, and ion-conductive polymer fibers. The matrix includes a reinforcing material, so the strength of the matrix is improved. Thus, the matrix can prevent the volume of the all-solid-state secondary battery 1 from changing excessively during charge / discharge and can prevent the deformation of the all-solid-state secondary battery 1. The reinforcing material included in the matrix includes, for example, a second fibrous material. The reinforcing material may include the second fibrous material, so the strength of the matrix can be increased more uniformly. The second fibrous material is, for example, a material having an aspect ratio of 3 or greater, 5 or greater, or 10 or greater. The second fibrous material may be, for example, a material having an aspect ratio of 3 to 100, 5 to 100, or 10 to 100. The second fibrous material is, for example, a flame-retardant material. Since the second fibrous material can be a flame-retardant material, the ignition caused by thermal runaway that occurs during the charge / discharge process of the all-solid-state secondary battery 1 or due to an external impact is effectively suppressed. The second fibrous material is, for example, glass fiber, metal oxide fiber, or ceramic fiber.

[0111] In addition to the matrix, the flame-retardant non-active member further includes a filler. The filler can be disposed in the matrix, on the surface of the matrix, or on both the inside and the surface. The filler includes, for example, inorganic materials. The filler included in the flame-retardant non-active member is, for example, a moisture absorbent, a flame retardant, or a lithium fixative. For example, the moisture absorbent can absorb moisture at a temperature lower than 100 °C to remove the moisture remaining in the all-solid-state secondary battery 1, thereby preventing the deterioration of the all-solid-state secondary battery 1. In addition, when the temperature of the all-solid-state secondary battery 1 rises to 150 °C or higher due to thermal runaway occurring during the charge / discharge process of the all-solid-state secondary battery 1 or due to an external impact, the moisture absorbent can release the absorbed moisture to effectively suppress the ignition of the all-solid-state secondary battery 1. The moisture absorbent includes, for example, metal hydroxides having moisture absorption properties. The metal hydroxides included in the filler are, for example, Mg(OH)2, Fe(OH)3, Sb(OH)3, Sn(OH)4, Ti(OH)3, Zr(OH)4, Al(OH)3, or a combination thereof. The flame retardant includes, for example, at least one selected from zinc borate, calcium zinc molybdate complex, MoO3, (NH4)2Mo2O7, Sb2O3, and Sb3O5. The lithium fixative can be, for example, a compound that fixes lithium by reacting with liquid lithium at a temperature of 180 °C or higher, which is the melting temperature of lithium. The lithium fixative can react with, for example, liquid lithium to change lithium into other insoluble compounds. The lithium fixative is, for example, a metal oxide that reacts with liquid lithium. The metal oxides included in the filler are, for example, TiO2, ZrO2, HfO2, ThO2, or a combination thereof. The metal oxide reacts with, for example, liquid lithium to generate Li2O and metal. The reaction formula is, for example, 4Li + MO2 → M + 2Li2O. The liquid lithium is fixed by reacting with the metal oxide to generate lithium oxide. The leakage of the liquid lithium that melts at a high temperature into the positive electrode can be suppressed. Therefore, the safety of the all-solid-state secondary battery can be improved.

[0112] With respect to 100 parts by weight of the flame-retardant non-active member, the content of the filler included in the flame-retardant non-active member is, for example, in the range of 1 part by weight to 80 parts by weight, 5 parts by weight to 80 parts by weight, 10 parts by weight to 80 parts by weight, 20 parts by weight to 80 parts by weight, 30 parts by weight to 80 parts by weight, 40 parts by weight to 80 parts by weight, 50 parts by weight to 80 parts by weight, 60 parts by weight to 80 parts by weight, or 65 parts by weight to 80 parts by weight.

[0113] The flame-retardant non-active member may further include, for example, a binder. The binder may include, for example, a curable polymer or a non-curable polymer. The curable polymer is a polymer cured by heat and / or pressure. The curable polymer is, for example, solid at room temperature. The flame-retardant non-active member includes, for example, a thermally press-curable film and / or its cured product. The thermally press-curable polymer is, for example, TSA-66 of Toray.

[0114] In addition to the above-mentioned substrate, reinforcing material, filler, and binder, the flame-retardant inactive member may further include other materials. The flame-retardant inactive member may further include, for example, at least one selected from paper, insulating polymers, ion-conductive polymers, insulating inorganic materials, oxide-based solid electrolytes, and sulfide-based solid electrolytes. The insulating polymer may be, for example, an olefin-based polymer such as polypropylene (PP) and polyethylene (PE).

[0115] The density of the substrate or reinforcing material included in the flame-retardant inactive member may be, for example, in the range of 10% to 300%, 10% to 150%, 10% to 140%, 10% to 130%, or 10% to 120% of the density of the negative electrode active material included in the first negative electrode active material layer 22.

[0116] The first inactive member 42 is a member that does not include an electrochemically active material (e.g., an electrode active material). The electrode active material is a material that adsorbs / desorbs lithium. The first inactive member 42 is a member composed of materials other than the electrode active material used in the art.

[0117] [Negative electrode layer: Negative electrode active material]

[0118] Referring to Figures 1 to 9 , the negative electrode layer 20 includes a first negative electrode active material layer 22.

[0119] The first negative electrode active material layer 22 is, for example, a metal layer. The metal layer may include, for example, lithium or a lithium alloy. The lithium metal is, for example, a lithium foil. Examples of the lithium alloy include Li-Al alloy, Li-Sn alloy, Li-In alloy, Li-Ag alloy, Li-Au alloy, Li-Zn alloy, Li-Ge alloy, Li-Si alloy, etc., but one or more embodiments are not limited thereto. Any material may be used as long as the material can be used as a lithium alloy in the art.

[0120] Optionally, the first negative electrode active material layer 22 includes, for example, a negative electrode active material and a binder.

[0121] The first negative electrode active material layer 22 includes a negative electrode active material, and the negative electrode active material is, for example, a negative electrode material that can form an alloy or compound with lithium.

[0122] The first negative electrode active material layer 22 includes a negative electrode active material, and the negative electrode active material has, for example, a particulate form. The average particle diameter of the negative electrode active material having a particulate form is, for example, 4 μm or less, 3 μm or less, 2 μm or less, 1 μm or less, 500 nm or less, 300 nm or less, or 100 nm or less. The average particle diameter of the negative electrode active material having a particulate form is, for example, in the range of 10 nm to 4 μm, 10 nm to 3 μm, 10 nm to 2 μm, 10 nm to 1 μm, 10 nm to 500 nm, 10 nm to 300 nm, or 10 nm to 100 nm. The negative electrode active material may have an average particle diameter within such a range, so that the reversible absorption and / or desorption of lithium during charge / discharge can be easier. The average particle diameter of the negative electrode active material is, for example, the median diameter (D50) measured using a laser type particle size distribution analyzer.

[0123] The first negative electrode active material layer 22 includes a negative electrode active material, and the negative electrode active material includes at least one selected from, for example, carbon-based negative electrode active materials and metal-based negative electrode active materials.

[0124] The carbon-based negative electrode active material includes, for example, amorphous carbon, crystalline carbon, porous carbon, or a combination thereof.

[0125] The carbon-based negative electrode active material is, for example, amorphous carbon. Examples of amorphous carbon include carbon black (CB), acetylene black (AB), furnace black (FB), Ketjen black (KB), graphene, etc., but one or more embodiments are not necessarily limited thereto. Any material can be used as long as the material is classified as amorphous carbon in the art. Amorphous carbon is carbon that has no crystallinity or has very low crystallinity and is different from crystalline carbon or graphite-based carbon.

[0126] The carbon-based negative electrode active material may be, for example, porous carbon. The pore volume of the porous carbon is, for example, in the range of 0.1 cc / g to 10.0 cc / g, 0.5 cc / g to 5 cc / g, or 0.1 cc / g to 1 cc / g. The average pore diameter of the porous carbon is, for example, in the range of 1 nm to 50 nm, 1 nm to 30 nm, or 1 nm to 10 nm. The Brunauer-Emmett-Teller (BET) specific surface area of the porous carbon is, for example, 100 m 2 / g to 3000 m 2 / g.

[0127] The metal-based negative electrode active material includes at least one selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn), but one or more embodiments are not necessarily limited thereto. Any material can be used as long as it is used as a metal-based negative electrode active material that forms an alloy or compound with lithium in the art. For example, nickel (Ni) does not form an alloy with lithium and thus is not a metal-based negative electrode active material.

[0128] The first negative electrode active material layer 22 includes one type of negative electrode active material among such negative electrode active materials or a mixture of a plurality of different negative electrode active materials. For example, the first negative electrode active material layer 22 includes only amorphous carbon or includes at least one selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). Optionally, the first negative electrode active material layer 22 includes a mixture of amorphous carbon and at least one selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). The mixing ratio of the mixture of amorphous carbon and gold, etc. is, for example, a weight ratio in the range of 99:1 to 1:99, 10:1 to 1:2, 5:1 to 1:1, or 4:1 to 2:1, but one or more embodiments are not necessarily limited to such a range. The mixing ratio is selected according to the required characteristics of the all-solid-state secondary battery 1. Since the negative electrode active material has such a composition, the cycle characteristics of the all-solid-state secondary battery 1 are further improved.

[0129] The first negative electrode active material layer 22 includes a negative electrode active material, and the negative electrode active material includes, for example, a mixture of first particles composed of amorphous carbon and second particles composed of a metal. Examples of the metal include, for example, gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), zinc (Zn), etc. The content of the second particles is in the range of 1 wt% to 99 wt%, 1 wt% to 60 wt%, 8 wt% to 60 wt%, 10 wt% to 50 wt%, 15 wt% to 40 wt%, or 20 wt% to 30 wt% relative to the total weight of the mixture. Since the second particles have a content in such a range, the cycle characteristics of the all-solid-state secondary battery 1 are, for example, further improved.

[0130] Optionally, the first negative electrode active material layer 22 includes a composite negative electrode active material. The composite negative electrode active material may include, for example, a carbonaceous carrier and a metal-based negative electrode active material supported on the carbonaceous carrier. The composite negative electrode active material may have a structure such that localization of the metal-based negative electrode active material in the first negative electrode active material layer can be prevented, and its uniform distribution can be obtained. Thereby, the cycle characteristics of the all-solid-state secondary battery 1 including the first negative electrode active material layer 22 are further improved.

[0131] The metal-based negative electrode active material supported on the carbonaceous carrier includes, for example, a metal, a metal oxide, a composite of a metal and a metal oxide, or a combination thereof. Examples of the metal include gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), zinc (Zn), etc. Examples of the metal oxide include gold (Au) oxide, platinum (Pt) oxide, palladium (Pd) oxide, silicon (Si) oxide, silver (Ag) oxide, aluminum (Al) oxide, bismuth (Bi) oxide, tin (Sn) oxide, zinc (Zn) oxide, etc. The metal oxide may include, for example, Au x O y (where 0 < x ≤ 2 and 0 < y ≤ 3), Pt x O y (where 0 < x ≤ 1 and 0 < y ≤ 2), Pd x O y (where 0 < x ≤ 1 and 0 < y ≤ 1), Si x O y (where 0 < x ≤ 1 and 0 < y ≤ 2), Ag x O y (where 0 < x ≤ 2 and 0 < y ≤ 1), Al x O y (where 0 < x ≤ 2 and 0 < y ≤ 3), Bi x O y (where 0 < x ≤ 2 and 0 < y ≤ 3), Sn x O y (where 0 < x ≤ 1 and 0 < y ≤ 2), Zn x O y (where 0 < x ≤ 1 and 0 < y ≤ 1) or a combination thereof. The composite of a metal and a metal oxide may include, for example, a composite of Au and Au x O y (where 0 < x ≤ 2 and 0 < y ≤ 3), a composite of Pt and Pt x O y (where 0 < x ≤ 1 and 0 < y ≤ 2), a composite of Pd and Pd x O yComplexes (where 0 < x ≤ 1 and 0 < y ≤ 1), Si and Si x O y Complexes (where 0 < x ≤ 1 and 0 < y ≤ 2), Ag and Ag x O y Complexes (where 0 < x ≤ 2 and 0 < y ≤ 1), Al and Al x O y Complexes (where 0 < x ≤ 2 and 0 < y ≤ 3), Bi and Bi x O y Complexes (where 0 < x ≤ 2 and 0 < y ≤ 3), Sn and Sn x O y Complexes (where 0 < x ≤ 1 and 0 < y ≤ 2), Zn and Zn x O y Complexes (where 0 < x ≤ 1 and 0 < y ≤ 2) or combinations thereof.

[0132] Carbonaceous carriers include, for example, amorphous carbon. Examples of amorphous carbon include CB, AB, FB, KB, graphene, activated carbon, carbon nanofibers (CNF), carbon nanotubes (CNT), etc., but one or more embodiments are not necessarily limited thereto. Any material can be used as long as it is classified as amorphous carbon in the art. Amorphous carbon is carbon that has no crystallinity or very low crystallinity and is distinct from crystalline carbon or graphite-like carbon. Carbonaceous materials are, for example, carbonaceous negative electrode active materials.

[0133] The composite negative electrode active material has, for example, a particulate form. The particle size of the composite negative electrode active material having a particulate form is, for example, in the range of 10 nm to 4 μm, 10 nm to 1 μm, 10 nm to 500 nm, 10 nm to 200 nm, or 10 nm to 100 nm. The composite negative electrode active material can have a particle size within such a range, so that the reversible absorption and / or desorption of lithium during charge / discharge can be easier. The metal-based negative electrode active material supported on the carbon-based carrier can have, for example, a particulate form. The particle size of the metal-based negative electrode active material can be, for example, in the range of 1 nm to 200 nm, 1 nm to 150 nm, 5 nm to 100 nm, or 10 nm to 50 nm. The carbon-based carrier can have, for example, a particulate form. The particle size of the carbon-based carrier can be, for example, in the range of 10 nm to 2 μm, 10 nm to 1 μm, 10 nm to 500 nm, 10 nm to 200 nm, or 10 nm to 100 nm. The carbon-based carrier can have a particle size within such a range, so that it can be more uniformly disposed in the first negative electrode active material layer. The carbon-based carrier can include, for example, nanoparticles having a particle size of 500 nm or less. Each of the particle size of the composite negative electrode active material, the particle size of the metal-based negative electrode active material, and the particle size of the carbon-based carrier is, for example, an average particle size. The average particle size is, for example, the median particle size (D50) measured by using a laser type particle size distribution analyzer. Optionally, the average particle size can be automatically determined by using software, for example, determined from an electron microscope image, or can be manually determined according to a manual.

[0134] [Negative electrode layer: Binder]

[0135] The binder included in the first negative electrode active material layer 22 is, for example, styrene-butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, PE, vinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, polymethyl methacrylate, etc., but one or more embodiments are not necessarily limited thereto. Any material can be used as long as the material is used as a binder in the art. The binder can be provided as a single binder or a plurality of different binders.

[0136] The first negative electrode active material layer 22 includes a binder and is thus stabilized on the negative electrode current collector 21. Further, although the volume and / or relative position of the first negative electrode active material layer 22 changes during the charge / discharge process, cracks in the first negative electrode active material layer 22 are suppressed. For example, when the first negative electrode active material layer 22 does not include a binder, the first negative electrode active material layer 22 would easily separate from the negative electrode current collector 21. At a portion of the negative electrode current collector 21 exposed due to the separation of the first negative electrode active material layer 22 from the negative electrode current collector 21, the negative electrode current collector 21 comes into contact with the solid electrolyte layer 30, which increases the possibility of a short circuit occurring. The first negative electrode active material layer 22 is formed, for example, by coating a slurry in which materials constituting the first negative electrode active material layer 22 are dispersed onto the negative electrode current collector 21 and drying the slurry. The first negative electrode active material layer 22 may include a binder, so that the negative electrode active material can be stably distributed in the slurry. For example, when the slurry is applied to the negative electrode current collector 21 by screen printing, clogging of the screen (e.g., clogging caused by aggregates of the negative electrode active material) can be suppressed.

[0137] [Negative electrode layer: Other additives]

[0138] The first negative electrode active material layer 22 may also include additives used in the all-solid-state secondary battery 1 according to related art, such as fillers, coating agents, dispersants, and ion conductive aids.

[0139] [Negative electrode layer: Solid electrolyte]

[0140] The first negative electrode active material layer 22 may also include a solid electrolyte. The solid electrolyte may be, for example, a material selected from the solid electrolytes included in the solid electrolyte layer 30. The solid electrolyte included in the first negative electrode active material layer 22 can serve as a reaction point where lithium metal starts to form in the first negative electrode active material layer 22, can serve as a space for storing the formed lithium metal, or can serve as a path for transporting lithium ions. The solid electrolyte may be omitted.

[0141] In the first negative electrode active material layer 22, for example, the content of the solid electrolyte may be high in the region adjacent to the solid electrolyte layer 30 and may be low in the region adjacent to the negative electrode current collector 21. The solid electrolyte in the first negative electrode active material layer 22 may have, for example, a concentration gradient in which the concentration decreases from the region adjacent to the solid electrolyte layer 30 toward the region adjacent to the negative electrode current collector 21.

[0142] [Negative electrode layer: First negative electrode active material layer]

[0143] The ratio B / A of the initial charge capacity B of the first negative electrode active material layer 22 to the initial charge capacity A of the positive electrode active material layer is, for example, in the range of 0.005 to 0.45. The initial charge capacity of the positive electrode active material layer 12 is determined from the first open circuit voltage to the maximum charge voltage vs. Li / Li + determined. The initial charge capacity of the first negative electrode active material layer 22 is determined from the second open circuit voltage to 0.01 V vs. Li / Li + determined. The maximum charge voltage is determined according to the type of the positive electrode active material. The maximum charge voltage can be, for example, 1.5 V, 2.0 V, 2.5 V, 3.0 V, 3.5 V, 4.0 V, 4.2 V, 4.3 V. For example, the maximum charge voltage of Li2S or a Li2S composite can be 2.5 V vs. Li / Li + . For example, the maximum charge voltage of Li2S or a Li2S composite can be 3.0 V vs. Li / Li + . The ratio B / A of the initial charge capacity B of the first negative electrode active material layer 22 to the initial charge capacity A of the positive electrode active material layer is, for example, in the range of 0.01 to 0.3, 0.01 to 0.2, or 0.05 to 0.1.

[0144] The initial charge capacity (mAh) of the positive electrode active material layer 12 is obtained by multiplying the charge specific capacity (mAh / g) of the positive electrode active material by the mass (g) of the positive electrode active material in the positive electrode active material layer 12. When various types of positive electrode active materials are used, the values of charge specific capacity × mass are calculated for each positive electrode active material, and the sum of these values is the initial charge capacity of the positive electrode active material layer 12. The initial charge capacity of the first negative electrode active material layer 22 is also calculated in the same manner. The initial charge capacity of the first negative electrode active material layer 22 is obtained by multiplying the charge specific capacity (mAh / g) of the negative electrode active material by the mass of the negative electrode active material in the first negative electrode active material layer 22. When various types of negative electrode active materials are used, the values of charge specific capacity × mass are calculated for each negative electrode active material, and the sum of these values is the initial charge capacity of the first negative electrode active material layer 22. The charge specific capacity of each of the positive electrode active material and the negative electrode active material can be measured by using an all-solid-state half-cell with lithium metal as the counter electrode. The initial charge capacity of each of the positive electrode active material layer 12 and the first negative electrode active material layer 22 can be directly measured by using an all-solid-state half-cell at a constant current density (for example, 0.1 mA / cm 2 ). It can be from the first open circuit voltage (OCV) until the maximum charge voltage of, for example, 3.0 V (vs. Li / Li +) At the operating voltage, measurements are performed on the positive electrode. Measurements can be performed on the negative electrode at an operating voltage from the second OCV down to 0.01 V of the negative electrode (e.g., lithium metal). For example, a all-solid-state half-cell including a positive electrode active material layer can be charged from the first OCV to 3.0 V at a constant current of 0.1 mA / cm 2 and a all-solid-state half-cell including a first negative electrode active material layer can be charged from the second OCV to 0.01 V at a constant current of 0.1 mA / cm 2 . The current density during the constant current charge can be, for example, 0.2 mA / cm 2 or 0.5 mA / cm 2 . A all-solid-state half-cell including a positive electrode active material layer can be charged, for example, from the first OCV to 2.5 V, 2.0 V, 3.5 V, or 4.0 V. The maximum charging voltage of the positive electrode active material layer can be determined by the maximum voltage of a battery that satisfies the safety conditions of JIS C 8712:2015 of the Japanese Standards Association.

[0145] When the initial charging capacity of the first negative electrode active material layer 22 is too low, the first negative electrode active material layer 22 becomes very thin. Therefore, during the repeated charge / discharge process, lithium dendrites formed between the first negative electrode active material layer 22 and the negative electrode current collector 21 cause the first negative electrode active material layer 22 to collapse, making it difficult to improve the cycle characteristics of the all-solid-state secondary battery 1. When the charging capacity of the first negative electrode active material layer 22 increases excessively, the energy density of the all-solid-state secondary battery 1 decreases, and the internal resistance of the all-solid-state secondary battery 1 increases due to the first negative electrode active material layer 22, making it difficult to improve the cycle characteristics of the all-solid-state secondary battery 1.

[0146] The thickness of the first negative electrode active material layer 22 is, for example, 50% or less, 40% or less, 30% or less, 20% or less, 10% or less, or 5% or less of the thickness of the positive electrode active material layer 12. The thickness of the first negative electrode active material layer 22 is, for example, in the range of 1% to 50%, 1% to 40%, 1% to 30%, 1% to 20%, 1% to 10%, or 1% to 5% of the thickness of the positive electrode active material layer 12. The thickness of the first negative electrode active material layer is, for example, in the range of 1 μm to 20 μm, 2 μm to 15 μm, or 3 μm to 10 μm. When the first negative electrode active material layer 22 is too thin, lithium dendrites formed between the first negative electrode active material layer 22 and the negative electrode current collector 21 cause the first negative electrode active material layer 22 to collapse, making it difficult to improve the cycle characteristics of the all-solid-state secondary battery 1. When the thickness of the first negative electrode active material layer 22 is excessively increased, the energy density of the all-solid-state secondary battery 1 decreases, and the internal resistance of the all-solid-state secondary battery 1 increases due to the first negative electrode active material layer 22, making it difficult to improve the cycle characteristics of the all-solid-state secondary battery 1. When the thickness of the first negative electrode active material layer 22 is decreased, for example, the initial charge capacity of the first negative electrode active material layer 22 also decreases.

[0147] [Negative electrode layer: Second negative electrode active material layer]

[0148] Although not shown in the drawings, the all-solid-state secondary battery 1 further includes a second negative electrode active material layer, which is disposed between the negative electrode current collector 21 and the first negative electrode active material layer 22 after charging. The second negative electrode active material layer is a metal layer including lithium or a lithium alloy. The metal layer includes lithium or a lithium alloy. Therefore, the second negative electrode active material layer is a metal layer including lithium and thus, for example, serves as a lithium reservoir. Examples of the lithium alloy may include Li-Al alloy, Li-Sn alloy, Li-In alloy, Li-Ag alloy, Li-Au alloy, Li-Zn alloy, Li-Ge alloy, Li-Si alloy, etc., but one or more embodiments are not limited thereto. Any material can be used as long as the material is used as a lithium alloy in the art. The second negative electrode active material layer is composed of one of such alloys or lithium or composed of different types of alloys. The second negative electrode active material layer is, for example, a plating layer. For example, during the charging process of the all-solid-state secondary battery 1, the second negative electrode active material layer precipitates between the first negative electrode active material layer 22 and the negative electrode current collector 21.

[0149] The thickness of the second negative electrode active material layer is not particularly limited, but is, for example, in the range of 1 μm to 500 μm, 1 μm to 200 μm, 1 μm to 150 μm, 1 μm to 100 μm, or 1 μm to 50 μm. When the second negative electrode active material layer is too thin, it is difficult for the second negative electrode active material layer to function as a lithium storage. When the second negative electrode active material layer is too thick, there is a possibility that the mass and volume of the all-solid-state secondary battery 1 increase, and the cycle characteristics of the all-solid-state secondary battery 1 deteriorate instead.

[0150] Optionally, in the all-solid-state secondary battery 1, for example, before the assembly of the all-solid-state secondary battery 1, the second negative electrode active material layer can be disposed between the negative electrode current collector 21 and the first negative electrode active material layer 22. When the second negative electrode active material layer is disposed between the negative electrode current collector 21 and the first negative electrode active material layer 22 before the assembly of the all-solid-state secondary battery 1, the second negative electrode active material layer is a metal layer containing lithium and thus functions as a lithium storage. For example, before the assembly of the all-solid-state secondary battery 1, a lithium foil can be disposed between the negative electrode current collector 21 and the first negative electrode active material layer 22.

[0151] When the all-solid-state secondary battery 1 is charged after assembly to precipitate the second negative electrode active material layer, since the all-solid-state secondary battery 1 does not include the second negative electrode active material layer during the assembly of the all-solid-state secondary battery 1, the energy density of the all-solid-state secondary battery 1 increases. During the charging of the all-solid-state secondary battery 1, the first negative electrode active material layer 22 is charged to exceed its charging capacity. That is, the first negative electrode active material layer 22 is overcharged. At the start of charging, lithium is absorbed in the first negative electrode active material layer 22. The negative electrode active material included in the first negative electrode active material layer 22 forms an alloy or a compound with the lithium ions moving from the positive electrode layer 10. When charging is carried out to exceed the capacity of the first negative electrode active material layer 22, for example, lithium precipitates on the rear side of the first negative electrode active material layer 22 (for example, between the negative electrode current collector 21 and the first negative electrode active material layer 22), and a metal layer corresponding to the second negative electrode active material layer is formed by the precipitated lithium. The second negative electrode active material layer is a metal layer mainly composed of lithium (for example, metallic lithium). For example, such a result is obtained because the negative electrode active material included in the first negative electrode active material layer 22 includes a material that forms an alloy or a compound with lithium. During discharging, the lithium in the first negative electrode active material layer 22 and the second negative electrode active material layer (for example, the lithium in the metal layer) is ionized to move toward the positive electrode layer 10. Therefore, in the all-solid-state secondary battery 1, lithium can be used as the negative electrode active material. In addition, the first negative electrode active material layer 22 covers the second negative electrode active material layer, thereby serving as a protective layer for the second negative electrode active material layer (for example, the metal layer), and at the same time for suppressing the precipitation growth of lithium dendrites. Therefore, the short circuit and the capacity reduction of the all-solid-state secondary battery 1 are suppressed, thereby improving the cycle characteristics of the all-solid-state secondary battery 1. In addition, when the second negative electrode active material layer is set by charging the all-solid-state secondary battery 1 after assembly, the negative electrode layer 20 (for example, the negative electrode current collector 21, the first negative electrode active material layer 22, and the region therebetween) is a Li-free region that does not include lithium (Li) in the initial state of the all-solid-state secondary battery 1 or in the state after its full discharge.

[0152] [Negative electrode layer: Negative electrode current collector]

[0153] The negative electrode current collector 21 is made of a material that does not react with lithium (that is, a material that does not form an alloy and a compound with lithium). Examples of the material constituting the negative electrode current collector 21 include copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), and nickel (Ni), but one or more embodiments are not necessarily limited thereto. Any material can be used as long as the material is used as an electrode current collector in the art. The negative electrode current collector 21 may be composed of one of the above metals or an alloy or a coating material of two or more types of the above metals. The negative electrode current collector 21 is in the form of a plate or a foil, for example.

[0154] For example, although not shown in the drawings, the all-solid-state secondary battery 1 may further include a thin film on one side of the negative electrode current collector 21, the thin film including an element that can form an alloy with lithium. The thin film is disposed between the negative electrode current collector 21 and the first negative electrode active material layer 22. The thin film includes, for example, an element that can form an alloy with lithium. Examples of the element that can form an alloy with lithium include gold, silver, zinc, tin, indium, silicon, aluminum, bismuth, etc., but one or more embodiments are not necessarily limited thereto. Any material can be used as long as the material can form an alloy with lithium in the art. The thin film is composed of one type of such metal or an alloy of various types of metals. The thin film may be disposed on one side of the negative electrode current collector 21 such that, for example, the second negative electrode active material layer in the form of a precipitate deposited between the thin film and the first negative electrode active material layer can be further flattened, and the cycle characteristics of the all-solid-state secondary battery 1 can be further improved.

[0155] The thickness of the thin film is, for example, in the range of 1 nm to 800 nm, 10 nm to 700 nm, 50 nm to 600 nm, or 100 nm to 500 nm. When the thickness of the thin film is less than 1 nm, it may be difficult for the thin film to function. When the film is too thick, the thin film itself may absorb lithium, so the amount of lithium precipitated at the negative electrode may decrease, which may reduce the energy density of the all-solid-state battery 1 and may deteriorate the cycle characteristics of the all-solid-state secondary battery 1. The thin film can be disposed on the negative electrode current collector 21 by, for example, vacuum deposition, sputtering, plating, etc., but one or more embodiments are not necessarily limited to such methods. Any method can be used as long as the thin film can be formed by a method in the art.

[0156] The negative electrode current collector 21 may include, for example, a base film and a metal layer provided on one or both sides of the base film. The base film may include, for example, a polymer. The polymer may include, for example, polyethylene terephthalate (PET), PE, PP, polybutylene terephthalate (PBT), polyimide (PI), or a combination thereof. The metal layer may include, for example, indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), or an alloy thereof. Since the negative electrode current collector 21 has such a structure, the weight of the electrode can be reduced, and thus the energy density of the all-solid-state secondary battery can be improved.

[0157] [Negative electrode layer: Third non-active member]

[0158] Refer to Figures 6 to 9 , the all-solid-state secondary battery 1 further includes a third non-active member 50 (50a, 50b, or 50c) provided on the other side of the negative electrode current collector 21.

[0159] The third non-active member 50 is different from the first non-active member 42 in that the third non-active member 50 additionally includes a conductive material to have conductivity. The third non-active member 50 is, for example, a conductive flame-retardant non-active member.

[0160] Examples of the conductive material include graphite, CB, AB, KB, super conductive acetylene black (Denka black), carbon fiber, CNT, graphene, metal fiber, metal powder, etc. The electronic conductivity of the third non-active member 50 at a temperature of 25 °C is, for example, 100 times or more, 1000 times or more, or 10000 times or more the electronic conductivity of the first non-active member 42 at a temperature of 25 °C.

[0161] The third non-active member 50 includes, for example, a matrix, a filler, and a conductive material. The matrix includes, for example, a substrate and a reinforcing material. The third non-active member 50 may also include a filler, a binder, etc. The content of the conductive material included in the third non-active member 50 is, for example, in the range of 1 part by weight to 30 parts by weight, 1 part by weight to 20 parts by weight, 1 part by weight to 15 parts by weight, 1 part by weight to 10 parts by weight, 5 parts by weight to 40 parts by weight, 5 parts by weight to 35 parts by weight, or 5 parts by weight to 30 parts by weight with respect to 100 parts by weight of the third non-active member 50.

[0162] The Young's modulus of the third non-active member 50 is lower than, for example, the Young's modulus of the negative electrode current collector 21. The Young's modulus of the third non-active member 50 is, for example, 50% or less, 30% or less, 10% or less, or 5% or less of the Young's modulus of the negative electrode current collector 21. The Young's modulus of the third non-active member 50 is, for example, in the range of 0.01% to 50%, 0.1% to 30%, 0.1% to 10%, or 1% to 5% of the Young's modulus of the negative electrode current collector 21. The Young's modulus of the third non-active member 50 is, for example, 100 MPa or less, 50 MPa or less, 30 MPa or less, 10 MPa or less, or 5 MPa or less. The Young's modulus of the third non-active member 50 is, for example, in the range of 0.01 MPa to 100 MPa, 0.1 MPa to 50 MPa, 0.1 MPa to 30 MPa, 0.1 MPa to 10 MPa, or 1 MPa to 5 MPa.

[0163] The third inactive member 50 (50a, 50b, or 50c) may have electrical conductivity and thus can be used as a negative electrode current collector. In addition, the third inactive member 50 (50a, 50b, or 50c) may have a Young's modulus lower than that of the negative electrode current collector 21, and thus can more effectively accommodate the volume change of the negative electrode layer 20 during charge / discharge of the all-solid-state secondary battery 1. Accordingly, the third inactive member 50 (50a, 50b, or 50c) can effectively relieve the internal stress caused by the volume change of the all-solid-state secondary battery 1 during charge / discharge, thereby improving the cycle characteristics of the all-solid-state secondary battery 1.

[0164] The thickness of the third inactive member 50 is, for example, greater than the thickness of the first negative electrode active material layer 22. The third inactive member 50 can be thicker than the first negative electrode active material layer 22, and thus can more effectively accommodate the volume change of the negative electrode layer 20 during charge / discharge. The thickness of the first negative electrode active material layer 22 is 50% or less, 40% or less, 30% or less, 20% or less, or 10% or less of the thickness of the third inactive member 50. The thickness of the first negative electrode active material layer 22 is, for example, in the range of 1% to 50%, 1% to 40%, 1% to 30%, 1% to 20%, or 1% to 10% of the thickness of the third inactive member 50. The thickness of the third inactive member 50 is, for example, in the range of 1 μm to 300 μm, 10 μm to 300 μm, 50 μm to 300 μm, or 100 μm to 200 μm. When the third inactive member 50 is too thin, it may be difficult to provide the desired effect, and when the third inactive member 50 is too thick, the energy density of the all-solid-state secondary battery 1 may decrease. The form of the third inactive member 50 is not particularly limited and can be selected according to the form of the all-solid-state secondary battery 1. The third inactive member 50 can be in the form of, for example, a sheet, a rod, or a washer.

[0165] The third inactive member 50 can be provided on, for example, one side or both sides of one all-solid-state secondary battery 1. Referring to Figure 9 , the third inactive member 50 can be provided, for example, between a plurality of stacked all-solid-state secondary batteries 1. The third inactive member 50 can be provided, for example, between a plurality of stacked all-solid-state secondary batteries 1, on their uppermost side and / or on their lowermost side.

[0166] During charging of the all-solid-state secondary battery 1, the increase in the volume of the negative electrode layer 20 is offset by the decrease in the volume of the positive electrode layer 10, and the third inactive member 50 accommodates the volume change of the negative electrode layer 20 to mitigate the volume change of the all-solid-state secondary battery 1 before and after charging.

[0167] [Positive electrode layer]

[0168] [Positive electrode layer: Positive electrode active material]

[0169] Reference Figures 1 to 9 , the positive electrode active material layer 12 includes, for example, a positive electrode active material and a solid electrolyte. The solid electrolyte included in the positive electrode active material layer 12 may be similar to or different from the solid electrolyte included in the solid electrolyte layer 30. The solid electrolyte is defined as in the part of the solid electrolyte layer 30.

[0170] The all-solid-state secondary battery may include a lithium-containing oxide-based positive electrode active material as the positive electrode active material. The lithium-containing oxide-based positive electrode active material may include, for example, at least one composite oxide of lithium and a metal selected from cobalt, manganese, nickel, and combinations thereof. The lithium-containing oxide-based positive electrode active material may include, for example, a compound represented by at least one of the following formulas: Li a A 1-b B' b D2 (where 0.90 ≤ a ≤ 1 and 0 ≤ b ≤ 0.5); Li a E 1-b B' b O 2-c D c (where 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, and 0 ≤ c ≤ 0.0); LiE 2-b B' b O 4-c D c (where 0 ≤ b ≤ 0.5 and 0 ≤ c ≤ 0.05); Li a Ni 1-b-c Co b B' c D α (where 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, and 0 < α ≤ 2); Li a Ni 1-b-c Co b B' c O 2-α F' α (where 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, and 0 < α < 2); Li a Ni 1-b-c Mn b B' c D α (where 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, and 0 < α ≤ 2); Li a Ni 1-b-c Mn b B' c O 2-α F' α (where 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, and 0 < α < 2); Li a Ni bE c G d O2 (where 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5 and 0.001 ≤ d ≤ 0.1); Li a Ni b Co c Mn d G e O2 (where 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0 ≤ d ≤ 0.5 and 0.001 ≤ e ≤ 0.1); Li a NiG b O2 (where 0.90 ≤ a ≤ 1 and 0.001 ≤ b ≤ 0.1); Li a CoG b O2 (where 0.90 ≤ a ≤ 1 and 0.001 ≤ b ≤ 0.1); Li a MnG b O2 (where 0.90 ≤ a ≤ 1 and 0.001 ≤ b ≤ 0.1); Li a Mn2G b O4 (where 0.90 ≤ a ≤ 1 and 0.001 ≤ b ≤ 0.1); LiV2O5; LiI'O2; LiNiVO4; Li (3-f) J2(PO4)3 (where 0 ≤ f ≤ 2); Li (3-f) Fe2(PO4)3 (where 0 ≤ f ≤ 2); and LiFePO4.

[0171] In the formula representing the above compound, A is Ni, Co, Mn, or a combination thereof; B' is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof; D is O, F, S, P, or a combination thereof; E is Co, Mn, or a combination thereof; F' is F, S, P, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; I' is Cr, V, Fe, Sc, Y, or a combination thereof; and J is V, Cr, Mn, Co, Ni, Cu, or a combination thereof. Compounds with a coating added to the surface of the above compound can also be used, and mixtures of the above compound and compounds with a coating added can also be used. The coating added to the surface of the above compound includes, for example, coating element compounds such as oxides or hydroxides of the coating elements, hydroxyoxides of the coating elements, oxocarbonates of the coating elements, or hydroxycarbonates of the coating elements. The compounds constituting the coating are amorphous or crystalline. The coating elements included in the coating include Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or a mixture thereof. The method for forming the coating is selected within the range that does not adversely affect the physical properties of the positive electrode active material. Coating methods include, for example, spraying, dipping, etc. Those skilled in the art can well understand the specific coating methods, so the detailed description thereof will be omitted.

[0172] The lithium-containing oxide-based positive electrode active material may include, for example, at least one selected from the group consisting of lithium transition metal oxides represented by the following Formulas 1 to 8:

[0173] Formula 1

[0174] Li a Ni x Co y M z O 2-b A b

[0175] Wherein, in Formula 1,

[0176] 1.0 ≤ a ≤ 1.2, 0 ≤ b ≤ 0.2, 0.8 ≤ x < 1, 0 ≤ y ≤ 0.3, 0 < z ≤ 0.3, and x + y + z = 1,

[0177] M is manganese (Mn), niobium (Nb), vanadium (V), magnesium (Mg), gallium (Ga), silicon (Si), tungsten (W), molybdenum (Mo), iron (Fe), chromium (Cr), copper (Cu), zinc (Zn), titanium (Ti), aluminum (Al), boron (B), or a combination thereof, and

[0178] A is F, S, Cl, Br, or a combination thereof;

[0179] Formula 2

[0180] LiNi x Co y Mn z O2

[0181] Formula 3

[0182] LiNi x Co y Al z O2

[0183] Wherein, in Formula 2 and Formula 3, 0.8 ≤ x ≤ 0.95, 0 ≤ y ≤ 0.2, 0 < z ≤ 0.2, and x + y + z = 1;

[0184] Formula 4

[0185] LiNi x Co y Mn z Al w O2

[0186] Wherein, in Formula 4, 0.8 ≤ x ≤ 0.95, 0 ≤ y ≤ 0.2, 0 < z ≤ 0.2, 0 < w ≤ 0.2, and x + y + z + w = 1;

[0187] Formula 5

[0188] Li a Co x M y O 2-b A b

[0189] Wherein, in Formula 5,

[0190] 1.0 ≤ a ≤ 1.2, 0 ≤ b ≤ 0.2, 0.9 ≤ x ≤ 1, 0 ≤ y ≤ 0.1, and x + y = 1,

[0191] M is manganese (Mn), niobium (Nb), vanadium (V), magnesium (Mg), gallium (Ga), silicon (Si), tungsten (W), molybdenum (Mo), iron (Fe), chromium (Cr), copper (Cu), zinc (Zn), titanium (Ti), aluminum (Al), boron (B) or a combination thereof, and

[0192] A is F, S, Cl, Br or a combination thereof;

[0193] Formula 6

[0194] Li a Ni x Mn y M' z O 2-b A b

[0195] Among them, in Formula 6,

[0196] 1.0 ≤ a ≤ 1.2, 0 ≤ b ≤ 0.2, 0 < x ≤ 0.3, 0.5 ≤ y < 1, 0 < z ≤ 0.3, and x + y + z = 1,

[0197] M' is cobalt (Co), niobium (Nb), vanadium (V), magnesium (Mg), gallium (Ga), silicon (Si), tungsten (W), molybdenum (Mo), iron (Fe), chromium (Cr), copper (Cu), zinc (Zn), titanium (Ti), aluminum (Al), boron (B) or a combination thereof, and

[0198] A is F, S, Cl, Br or a combination thereof;

[0199] Formula 7

[0200] Li a M1 x M2 y PO 4-b X b

[0201] Among them, in Formula 7, 0.90 ≤ a ≤ 1.1, 0 ≤ x ≤ 0.9, 0 ≤ y ≤ 0.5, 0.9 < x + y < 1.1, and 0 ≤ b ≤ 2, M1 is chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zirconium (Zr) or a combination thereof,

[0202] M2 is magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), titanium (Ti), zinc (Zn), boron (B), niobium (Nb), gallium (Ga), indium (In), molybdenum (Mo), tungsten (W), aluminum (Al), silicon (Si), chromium (Cr), vanadium (V), scandium (Sc), yttrium (Y) or a combination thereof, and X is O, F, S, P or a combination thereof; and

[0203] Formula 8

[0204] Li a M3 z PO4

[0205] Among them, in Formula 8, 0.90 ≤ a ≤ 1.1, 0.9 ≤ z ≤ 1.1, and

[0206] M3 is chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zirconium (Zr) or a combination thereof.

[0207] The all-solid-state secondary battery may include a Li₂S-containing composite as a positive electrode active material, and the Li₂S-containing composite is a lithium-containing sulfide-based positive electrode active material. In this case, interruption of the ion and / or electron transport path caused by volume expansion of a non-lithium-containing sulfide-based positive electrode active material (e.g., sulfur (S)) during initial discharge is prevented. Prevention of the interruption of the ion and / or electron transport path improves the cycle characteristics of the all-solid-state secondary battery.

[0208] Optionally, the all-solid-state secondary battery may include a lithium-containing sulfide-based positive electrode active material as the positive electrode active material. The lithium-containing sulfide-based positive electrode active material is, for example, an electrode material in which lithium is added to a sulfur-based positive electrode active material. The sulfur-based positive electrode active material includes, for example, a sulfur-based material, a composite containing a sulfur-based material, or a combination thereof. The sulfur-based material may be, for example, inorganic sulfur, Li₂S n (n>1), a disulfide compound, an organic sulfur compound, a carbon-sulfur polymer, or a combination thereof. The sulfur-containing composite may be a composite containing inorganic sulfur, Li₂S n (n>1), a disulfide compound, an organic sulfur compound, a carbon-sulfur polymer, or a combination thereof. The composite of the sulfur-based material may include, for example: a composite of a sulfur-based material and carbon; a composite of a sulfur-based material, carbon, and a solid electrolyte; a composite of a sulfur-based material and a solid electrolyte; a composite of a sulfur-based material and a metal carbide; a composite of a sulfur-based material, carbon, and a metal carbide; a composite of a sulfur-based material and a metal nitride; a composite of a sulfur-based material, carbon, and a metal nitride; or a combination thereof. Since the lithium-containing sulfide-based positive electrode active material provides a higher discharge capacity per unit weight than an oxide-based positive electrode active material, the energy density per unit weight of the all-solid-state secondary battery including the lithium-containing sulfide-based positive electrode active material can be improved.

[0209] The lithium-containing sulfide-based positive electrode active material includes, for example, a Li₂S-containing composite. By including the Li₂S-containing composite having a high capacity as the lithium-containing sulfide-based positive electrode active material, the use of lithium metal can be omitted when manufacturing the all-solid-state secondary battery. Lithium metal may have high reactivity and high ductility, so that the batch productivity during battery manufacturing may be reduced. Therefore, the batch productivity of the all-solid-state secondary battery can be improved. Since lithium metal is omitted from the negative electrode layer, the volume of the negative electrode layer is reduced, thereby improving the energy density per unit volume of the all-solid-state secondary battery and constituting an all-solid-state secondary battery having a simpler structure.

[0210] For example, a lithium-containing sulfide-based positive electrode active material (e.g., a Li2S composite) undergoes de-lithiation during initial charging, resulting in a volume reduction, and then the volume increases again due to lithiation during subsequent discharging. Therefore, since the volume of the lithium-containing sulfide-based positive electrode active material changes while maintaining an ion and / or electron transport path through a conductive material or the like disposed around the lithium-containing sulfide-based positive electrode active material, the possibility of interruption of the ion and / or electron transport path is low. On the other hand, for example, a sulfur-based positive electrode active material (e.g., S) undergoes lithiation during initial discharging, resulting in a volume increase, and then the volume decreases again due to de-lithiation during subsequent charging. Therefore, since the initial ion and / or electron transport path of a conductive material or the like disposed around the sulfur-based positive electrode active material may collapse due to the initial volume increase of the sulfur-based positive electrode active material, the possibility of interruption of the ion and / or electron transport path is high.

[0211] The particle size of the lithium-containing sulfide-based positive electrode active material can be, for example, in the range of 1 nm to 50 μm, 10 nm to 50 μm, 50 nm to 40 μm, 100 nm to 30 μm, 500 nm to 30 μm, or 1 μm to 20 μm. Since the lithium-containing sulfide-based positive electrode active material has a particle size within such a range, the cycle characteristics of the all-solid-state secondary battery including the lithium-containing sulfide-based positive electrode active material can be further improved.

[0212] The Li2S composite is, for example, a composite of Li2S and a conductive material. The conductive material is, for example, an ion-conductive material, an electron-conductive material, or a combination thereof.

[0213] The electron conductivity of the electron-conductive material is, for example, 1.0×10 3 S / m, 1.0×10 4 S / m, or 1.0×10 5S / m or greater. The electronically conductive material is, for example, in the form of a granular electronically conductive material, a plate-like electronically conductive material, a rod-like electronically conductive material, or a combination thereof, but is not limited thereto. The electronically conductive material may be, for example, carbon, metal powder, metal compound, etc. When carbon is included as the electronically conductive material, carbon has high electronic conductivity and is light, thereby realizing a all-solid-state secondary battery with a high energy density per unit mass. The electronically conductive material may have pores. Since the electronically conductive material has pores, Li2S can be included in the pores, thereby increasing the contact area between Li2S and the electronically conductive material and increasing the specific surface area of Li2S. The pore volume is, for example, in the range of 0.1 cc / g to 20.0 cc / g, 0.5 cc / g to 10 cc / g, or 0.5 cc / g to 5 cc / g. The average pore diameter is, for example, in the range of 1 nm to 100 nm, 1 nm to 50 nm, or 1 nm to 20 nm. When the average pore diameter is 15 nm or less, the BET specific surface area of the electronically conductive material having pores is in the range of 200 m 2 / g to 4500 m 2 / g, and when the average pore diameter exceeds 15 nm, the BET specific surface area of the electronically conductive material having pores is in the range of 100 m 2 / g to 2500 m 2 / g. The BET specific surface area, pore diameter, pore volume, and average pore diameter can be obtained, for example, by using the nitrogen absorption method.

[0214] The ionic conductivity of the ionically conductive material is, for example, 1.0×10 -5 S / m, 1.0×10 -4 S / m, or 1.0×10 -3 S / m or greater. The ionically conductive material may have pores. Since the ionically conductive material has pores, Li2S can be included in the pores, thereby increasing the contact area between Li2S and the ionically conductive material and increasing the specific surface area of Li2S. The ionically conductive material is, for example, in the form of a granular ionically conductive material, a plate-like ionically conductive material, a rod-like ionically conductive material, or a combination thereof, but is not limited thereto. The ionically conductive material may be, for example, a sulfide-based solid electrolyte, an oxide-based solid electrolyte, etc. When a sulfide-based solid electrolyte is included as the ionically conductive material, the sulfide-based solid electrolyte may have high ionic conductivity and can be molded into various shapes, thereby realizing a all-solid-state secondary battery with a large capacity.

[0215] The Li₂S-containing composite includes, for example: a composite of Li₂S and carbon; a composite of Li₂S, carbon, and a solid electrolyte; a composite of Li₂S and a solid electrolyte; a composite of Li₂S and a metal carbide; a composite of Li₂S, carbon, and a metal carbide; a composite of Li₂S and a metal nitride; a composite of Li₂S, carbon, and a metal nitride; or a combination thereof.

[0216] The Li₂S-containing composite includes, for example: a composite of Li₂S and carbon; a composite of Li₂S, carbon, and a solid electrolyte; a composite of Li₂S and a solid electrolyte; a composite of Li₂S and a metal carbide; a composite of Li₂S, carbon, and a metal carbide; a composite of Li₂S and a metal nitride; a composite of Li₂S, carbon, and a metal nitride; a composite of Li₂S and a metal; a composite of Li₂S, a metal, and carbon; or a combination thereof.

[0217] The composite of Li₂S and carbon includes carbon. As the carbon, for example, any material can be used as long as the material can be a material including carbon atoms and can be used as a conductive material in the art. The carbon can be, for example, crystalline carbon, amorphous carbon, or a combination thereof. The carbon can be, for example, a sintered product of a carbon precursor. The carbon can include, for example, carbon nanostructures. The carbon nanostructures can include, for example, one-dimensional carbon nanostructures, two-dimensional carbon nanostructures, three-dimensional carbon nanostructures, or a combination thereof. The carbon nanostructures can include, for example, CNT, CNF, carbon nanobelts, carbon nanorods, graphene, graphene oxide (GO), reduced graphene oxide (rGO), graphene balls (GB), or a combination thereof. The carbon can be, for example, porous carbon or non-porous carbon. The porous carbon can include, for example, periodic and regular two-dimensional or three-dimensional pores. The porous carbon can include, for example, CBs such as KB, AB, Denka black, thermal black, or channel black; graphite; activated carbon; or a combination thereof. The form of the carbon can be, for example, a particulate form, a sheet form, a flake form, etc., but one or more embodiments are not limited thereto. Any material can be used as long as the material is used as carbon in the art. The method for preparing the composite of Li₂S and carbon can be a dry method, a wet method, or a combination thereof, but is not limited thereto. In the art, the method for preparing the composite of Li₂S and carbon can include, for example, grinding, heat treatment, deposition, etc., but one or more embodiments are not limited thereto. Any method can be used as long as the method is used in the art.

[0218] The composite of Li2S, carbon, and a solid electrolyte includes carbon and a solid electrolyte. The carbon can be as defined in the composite of Li2S and carbon described above. As the solid electrolyte, for example, any material can be used as long as it is used as an ion-conductive material in the art. The solid electrolyte is, for example, an inorganic solid electrolyte. The solid electrolyte is, for example, a crystalline solid electrolyte, an amorphous solid electrolyte, or a combination thereof. The solid electrolyte is, for example, a sulfide-based solid electrolyte, an oxide-based solid electrolyte, a lithium salt compound, or a combination thereof. The sulfide-based solid electrolyte can include, for example, Li, S, and P and can optionally further include a halogen element. The sulfide-based solid electrolyte can be selected from the sulfide-based solid electrolytes used in the solid electrolyte layer. For example, the sulfide-based solid electrolyte can have an ionic conductivity of 1×10 -5 S / cm or greater at room temperature. The sulfide-based solid electrolyte can include, for example, those selected from Li3PO4-Li2SO4, Li2S-P2S5, Li2S-P2S5-LiX (where X is a halogen element), Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-Z m S n (where m and n are each positive numbers, and Z is one of Ge, Zn, and Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (where p and q are each positive numbers, and M is one of P, Si, Ge, B, Al, Ga, and In), Li 7-x PS 6- x Cl x (where 0 ≤ x ≤ 2), Li 7-x PS 6-x Br x (where 0 ≤ x ≤ 2), and Li 7-x PS 6-x I x (where 0 ≤ x ≤ 2), and at least one of them. The oxide-based solid electrolyte can include, for example, Li, O, and a transition metal element and can optionally further include other elements. For example, the oxide-based solid electrolyte can have an ionic conductivity of 1×10 -5A solid electrolyte with an ionic conductivity of S / cm or greater. The oxide-based solid electrolyte can be selected from the oxide-based solid electrolytes used in the solid electrolyte layer. The lithium salt compound is, for example, an inorganic compound. The solid electrolyte includes, for example, a lithium salt compound, and the lithium salt compound does not include, for example, a sulfur (S) atom. The lithium salt compound can be, for example, a binary compound including lithium and one element selected from Groups 13 to 17 of the periodic table. The binary compound can include, for example, at least one selected from LiF, LiCl, LiBr, LiI, LiH, Li2S, Li2O, Li2Se, Li2Te, Li3N, Li3P, Li3As, Li3Sb, LiI3, and LiB3. The lithium salt compound can be, for example, a ternary compound including lithium and two elements selected from Groups 13 to 17 of the periodic table. The ternary compound includes, for example, at least one selected from Li3OCl, LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiAlO2, LiAlCl4, LiNO3, Li2CO3, LiBH4, Li2SO4, Li3BO3, Li3PO4, Li4NCl, Li5NCl2, and Li3BN2. The lithium salt compound includes at least one lithium halide compound selected from LiF, LiCl, LiBr, and LiI. The solid electrolyte can be, for example, a mixture of a sulfide-based solid electrolyte and a lithium salt compound. For example, the solid electrolyte is a mixture of Li3PO4-Li2SO4 and a binary lithium salt compound or a mixture of Li3PO4-Li2SO4 and a ternary lithium salt compound.

[0219] The composite of Li2S and the solid electrolyte includes the solid electrolyte. The solid electrolyte is as defined above for the solid electrolyte used in the composite of Li2S, carbon, and the solid electrolyte. The composite of Li2S and the solid electrolyte includes, for example, a composite of Li2S and at least one lithium salt selected from LiF, LiCl, LiBr, LiI, LiH, Li2S, Li2O, Li2Se, Li2Te, Li3N, Li3P, Li3As, Li3Sb, LiI3, and LiB3.

[0220] The composite of Li2S and the metal carbide includes the metal carbide. The metal carbide is, for example, a two-dimensional metal carbide. The two-dimensional metal carbide is, for example, MXene. The two-dimensional metal carbide is, for example, represented by M n+1 C n T x , where M is a transition metal, T is a terminal group, T is O, OH, and / or F, n = 1, 2, or 3, and x is the number of terminal groups. The two-dimensional metal carbide is, for example, Ti2CT x , (Ti 0.5 , Nb 0.5 )2CT x, Nb2CT x , V2CT x , Ti3C2T x , (V 0.5 , Cr 0.5 )3C2T x , Ti3CNT x , Ta4C3T x , Nb4C3T x or a combination thereof. The surface of the two-dimensional metal carbide is capped with O, OH, and / or F.

[0221] The composite of Li2S, carbon, and metal carbide includes carbon and metal carbide. The carbon is as defined in the composite of Li2S and carbon above. The metal carbide is as defined in the composite of Li2S and metal carbide above.

[0222] The composite of Li2S and metal nitride includes metal nitride. The metal nitride is, for example, a two-dimensional metal nitride. The two-dimensional metal nitride is, for example, represented by M n+1 N n T x , where M is a transition metal, T is a capping group, T is O, OH, and / or F, n = 1, 2, or 3, and x is the number of capping groups. The surface of the two-dimensional metal nitride is capped with O, OH, and / or F.

[0223] The composite of Li2S, carbon, and metal nitride includes carbon and metal nitride. The carbon is as defined in the composite of Li2S and carbon above. The metal nitride is as defined in the composite of Li2S and metal nitride above.

[0224] Relative to the total weight of the positive electrode active material layer 12, the content of the sulfide-based positive electrode active material included in the positive electrode active material layer 12 can be, for example, in the range of 10 wt% to 90 wt%, 10 wt% to 80 wt%, 10 wt% to 70 wt%, 10 wt% to 60 wt%, or 10 wt% to 50 wt%.

[0225] For example, the positive electrode active material layer 12 may further include a sulfide compound different from Li2S. The sulfide compound may be, for example, a compound including a sulfur element and a metal element other than Li. For example, the sulfide compound may be a compound including a sulfur element and at least one metal element having an atomic weight of 10 or more and belonging to Groups 1 to 14 of the periodic table. The sulfide compound may be, for example, FeS2, VS2, NaS, MnS, FeS, NiS, CuS, or a combination thereof. The positive electrode active material layer may further include a sulfide compound, so that the cycle characteristics of the all-solid-state secondary battery can be further improved. The content of the sulfide compound included in the positive electrode active material layer 12 and different from Li2S may be 10 wt% or less, 5 wt% or less, 3 wt% or less, or 1 wt% or less of the total weight of the positive electrode active material layer 12.

[0226] [Positive electrode layer: Solid electrolyte]

[0227] The positive electrode active material layer 12 may further include, for example, a solid electrolyte. The solid electrolyte may be, for example, a sulfide solid electrolyte. The solid electrolyte included in the positive electrode layer 10 may be the same as or different from the solid electrolyte included in the solid electrolyte layer 30. The solid electrolyte is as defined in a part of the solid electrolyte layer 30.

[0228] The D50 average particle size of the solid electrolyte included in the positive electrode active material layer 12 may be smaller than the D50 average particle size of the solid electrolyte included in the solid electrolyte layer 30. For example, the D50 average particle size of the solid electrolyte included in the positive electrode active material layer 12 may be 90% or less, 80% or less, 70% or less, 60% or less, 50% or less, 40% or less, 30% or less, or 20% or less of the D50 average particle size of the solid electrolyte included in the solid electrolyte layer 30. The D50 average particle size is, for example, the median particle size (D50). The median particle size (D50) is the particle size corresponding to 50% cumulative volume when calculating the particle size distribution measured by the laser diffraction method from particles having a smaller particle size.

[0229] The content of the solid electrolyte included in the positive electrode active material layer 12 may be, for example, in the range of 1 wt% to 40 wt%, 1 wt% to 30 wt%, 1 wt% to 20 wt%, or 1 wt% to 10 wt% of the total weight of the positive electrode active material layer 12.

[0230] [Positive electrode layer: Conductive material]

[0231] The positive electrode active material layer 12 may further include a conductive material. The conductive material may be, for example, a carbon-based conductive material, a metal-based conductive material, or a combination thereof. The carbon-based conductive material may be, for example, graphite, CB, AB, KB, carbon fiber, or a combination thereof, but one or more embodiments are not limited thereto. Any material may be used as long as it is used as a carbon-based conductive material in the art. The metal-based conductive material may be metal powder, metal fiber, or a combination thereof, but one or more embodiments are not limited thereto. Any material may be used as long as it is used as a metal-based conductive material in the art. The content of the conductive material included in the positive electrode active material layer 12 may be, for example, in the range of 1 wt% to 30 wt%, 1 wt% to 20 wt%, or 1 wt% to 10 wt% of the total weight of the positive electrode active material layer 12.

[0232] [Positive electrode layer: Binder]

[0233] The positive electrode active material layer 12 may further include a binder. The binder includes, for example, SBR, polytetrafluoroethylene, polyvinylidene fluoride, PE, etc., but one or more embodiments are not limited thereto. Any material may be used as long as it is used as a binder in the art. The content of the binder included in the positive electrode active material layer 12 may be, for example, in the range of 1 wt% to 10 wt% of the total weight of the positive electrode active material layer 12. The binder may be omitted.

[0234] [Positive electrode layer: Other additives]

[0235] In addition to the above positive electrode active material, solid electrolyte, binder, and conductive material, the positive electrode active material layer 12 may further include, for example, additives such as fillers, coating agents, dispersants, and ion conductive aids.

[0236] As the fillers, coating agents, dispersants, ion conductive aids, etc. that may be included in the positive electrode active material layer 12, known materials commonly used in the electrodes of all-solid-state secondary batteries may be used.

[0237] [Positive electrode layer: Positive electrode current collector]

[0238] The positive electrode current collector 11 may be provided as a plate, foil, etc. made of, for example, indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), or an alloy thereof. The positive electrode current collector 11 may be omitted. The thickness of the positive electrode current collector 11 is, for example, in the range of 1 μm to 100 μm, 1 μm to 50 μm, 5 μm to 25 μm, or 10 μm to 20 μm.

[0239] The positive electrode current collector 11 may include, for example, a base film and metal layers provided on one or both sides of the base film. The base film may include, for example, a polymer. The polymer may include, for example, PET, PE, PP, PBT, PI, or a combination thereof. The metal layer may include, for example, indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), or an alloy thereof. Since the positive electrode current collector 11 has such a structure, the weight of the electrode can be reduced, thereby improving the energy density of the all-solid-state secondary battery.

[0240] [Positive electrode layer: Second non-active member]

[0241] Refer to Figures 1 to 9 , the positive electrode layer 10 includes a positive electrode current collector 11 and a positive electrode active material layer 12 provided on one side of the positive electrode current collector 11. The second non-active member 41 is provided on the side surface of the positive electrode layer 10.

[0242] The second non-active member 41 provided on the side surface of the positive electrode layer 10 may be selected from the first non-active members 42 provided on the side surface of the negative electrode layer 20 described above.

[0243] Refer to Figure 2 and Figure 7 , the second non-active member 41 is provided on the side surface of the positive electrode active material layer 12 and is provided between the solid electrolyte layer 30 and the positive electrode current collector 11 opposite to the solid electrolyte layer 30. The second non-active member 41 is not provided on the side surface of the positive electrode current collector 11. Refer to Figure 1 and Figures 3 to 6 , the second non-active member 41 is provided on the side surface of the positive electrode active material layer 12 and the side surface of the positive electrode current collector 11. The second non-active member 41 is included to prevent cracks in the solid electrolyte layer 30 during the manufacture and / or charge / discharge of the all-solid-state secondary battery 1, thereby improving the cycle characteristics of the all-solid-state secondary battery 1. In the all-solid-state secondary battery 1 that does not include the second non-active member 41, uneven pressure is applied to the solid electrolyte layer 30 in contact with the positive electrode layer 10 during the manufacture and / or charge / discharge of the all-solid-state secondary battery 1, thereby causing cracks in the solid electrolyte layer 30, and lithium metal grows through the cracks, thereby increasing the possibility of short circuit.

[0244] Refer to Figures 1 to 9 , in the all-solid-state secondary battery 1, the thickness of the second non-active member 41 is, for example, greater than the thickness of the positive electrode active material layer 12. The thickness of the second non-active member 41 is, for example, greater than the thickness of the solid electrolyte layer 30.

[0245] Refer to Figures 1 to 9, the second non-active member 41 surrounds the side surface of the positive electrode layer 10 and is in contact with the solid electrolyte layer 30. The second non-active member 41 can surround the side surface of the positive electrode layer 10 and can be in contact with the solid electrolyte layer 30, thereby effectively suppressing cracks in the solid electrolyte layer 30 that are caused by a pressure difference during the pressing process in a portion of the solid electrolyte layer 30 that is not in contact with the positive electrode layer 10. The second non-active member 41 surrounds the side surface of the positive electrode layer 10 and is separated from the negative electrode layer 20 (more specifically, the first negative electrode active material layer 22). The second non-active member 41 surrounds the side surface of the positive electrode layer 10, is in contact with the solid electrolyte layer 30, and is separated from the negative electrode layer 20. Therefore, the possibility of short circuit due to physical contact between the positive electrode layer 10 and the first negative electrode active material layer 22 or due to overcharging of lithium is suppressed. The second non-active member 41 is provided on both the side surface of the positive electrode active material layer 12 and the side surface of the positive electrode current collector 11, thereby more effectively suppressing the possibility of short circuit due to contact between the positive electrode current collector 11 and the negative electrode layer 20.

[0246] Referring to Figures 1 to 9 , the second non-active member 41 (41a or 41b) extends from the side surface of the positive electrode layer 10 to the end of the solid electrolyte layer 30. The second non-active member 41 extends to the end of the solid electrolyte layer 30, thereby suppressing the generation of cracks at the end of the solid electrolyte layer 30. The end of the solid electrolyte layer 30 is the outermost portion that is in contact with the side surface of the solid electrolyte layer 30. The second non-active member 41 extends to the outermost portion that is in contact with the side surface of the solid electrolyte layer 30. The second non-active member 41 is separated from the negative electrode layer 20 (more specifically, the first negative electrode active material layer 22). The second non-active member 41 extends to the end of the solid electrolyte layer 30 but does not contact the negative electrode layer 20. For example, the second non-active member 41 fills the space extending from the side surface of the positive electrode layer 10 to the end of the solid electrolyte layer 30.

[0247] The area of the positive electrode active material layer 12 or the positive electrode layer 10 can be smaller than the area of the first negative electrode active material layer 22 or the negative electrode layer 20. The area of the positive electrode active material layer 12 or the positive electrode layer 10 can be smaller than the area of the solid electrolyte layer 30.

[0248] The second non-active member 41 can be a washer. By using a washer as the second non-active member 41, cracks in the solid electrolyte layer 30 caused by a pressure difference during the pressing process can be effectively suppressed.

[0249] The second non-active member 41 has, for example, a single-layer structure. Optionally, although not shown in the drawings, the second non-active member 41 can have a multi-layer structure. The second non-active member 41 having a single-layer structure or a multi-layer structure is as defined by the first non-active member 42.

[0250] Although not shown in the drawings, part or all of the second inactive member 41 (41a or 41b) may be provided so as to be spaced apart from the side surface of the positive electrode active material layer 12 (12a or 12b). Part or all of the second inactive member 41 (41a or 41b) may be provided so as to be spaced apart from the side surface of the positive electrode active material layer 12 (12a or 12b), so that the manufacturing process of the all-solid-state secondary battery 1 can be made easier, and the manufacturing speed of the all-solid-state secondary battery 1 can be increased. Since part or all of the second inactive member 41 (41a or 41b) is provided so as to be spaced apart from the side surface of the positive electrode active material layer 12 (12a or 12b), during charge / discharge, the volume change toward the side surface of the positive electrode active material layer 12 (12a or 12b) can be more effectively accommodated, thereby further improving the life characteristics of the all-solid-state secondary battery 1. The distances between the second inactive member 41 (41a and 41b) and the side surfaces of the positive electrode active material layer 12 (12a and 12b) are each independently, for example, in the range of 0.1 μm to 10 mm, 1 μm to 1 mm, 1 μm to 500 μm, 1 μm to 100 μm, 1 μm to 50 μm, or 1 μm to 10 μm.

[0251] Referring to Figures 1 to 9 , the second inactive member 41 is, for example, a flame-retardant inactive member. The flame-retardant inactive member used as the second inactive member 41 may be selected from the flame-retardant inactive members used in the first inactive member 42 described above.

[0252] [Solid electrolyte layer]

[0253] [Solid electrolyte layer: Solid electrolyte]

[0254] Referring to Figures 1 to 9 , the solid electrolyte layer 30 includes an electrolyte provided between the positive electrode layer 10 and the negative electrode layer 20. The electrolyte may include, for example, a solid electrolyte, a gel electrolyte, or a combination thereof.

[0255] The all-solid-state secondary battery includes a solid electrolyte layer, and thus prevents polysulfides generated during charge / discharge of the lithium sulfide-based positive electrode active material from moving to the negative electrode layer. Therefore, side reactions between the polysulfides and the negative electrode active material are suppressed.

[0256] The solid electrolyte may include, for example, a sulfide-based solid electrolyte, an oxide-based solid electrolyte, a polymer solid electrolyte, or a combination thereof.

[0257] The solid electrolyte is, for example, a sulfide-based solid electrolyte. The sulfide-based solid electrolyte may include, for example, those selected from Li2S-P2S5, Li2S-P2S5-LiX (where X is a halogen element), Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-Z m S n (where m and n are each a positive number, and Z is one of Ge, Zn, and Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (where p and q are each a positive number, and M is one of P, Si, Ge, B, Al, Ga, and In), Li 7-x PS 6-x Cl x (where 0 ≤ x ≤ 2), Li 7-x PS 6-x Br x (where 0 ≤ x ≤ 2), and Li 7-x PS 6-x I x (where 0 ≤ x ≤ 2), and at least one of them. For example, the sulfide-based solid electrolyte is prepared by treating starting materials such as Li2S or P2S5 via melt quenching or mechanical grinding. In addition, after such treatment, heat treatment can be performed. The solid electrolyte can be in an amorphous state, a crystalline state, or a mixed state of amorphous and crystalline states. In addition, the solid electrolyte can be, for example, a material that includes at least sulfur (S), phosphorus (P), and lithium (Li) as constituent elements among the above materials of the sulfide-based solid electrolyte. For example, the solid electrolyte can be a material including Li2S-P2S5. When using a material including Li2S-P2S5 as the sulfide-based solid electrolyte material for forming the solid electrolyte, the mixing molar ratio of Li2S to P2S5 (e.g., Li2S:P2S5) is in the range of 20:80 to 90:10, 25:75 to 90:10, 30:70 to 70:30, or 40:60 to 60:40.

[0258] The sulfide-based solid electrolyte may include, for example, a thiogermanate-type solid electrolyte represented by the following formula 9:

[0259] Formula 9

[0260] Li +12-n-x A n+ X 2- 6-x Y - x 。

[0261] In the above formula, A is P, As, Ge, Ga, Sb, Si, Sn, Al, In, Ti, V, Nb or Ta, X is S, Se or Te, Y is Cl, Br, I, F, CN, OCN, SCN or N3, 1 ≤ n ≤ 5, and 0 ≤ x ≤ 2. The sulfide solid electrolyte may be, for example, a thiogermanate compound including at least one selected from Li 7-x PS 6-x Cl x (where 0 ≤ x ≤ 2), Li 7-x PS 6-x Br x (where 0 ≤ x ≤ 2) and Li 7-x PS 6-x I x (where 0 ≤ x ≤ 2). The sulfide solid electrolyte may be, for example, a thiogermanate compound including at least one selected from Li6PS5Cl, Li6PS5Br and Li6PS5I.

[0262] The thiogermanate solid electrolyte may have a density of 1.5 g / cc to 2.0 g / cc. Since the thiogermanate solid electrolyte has a density of 1.5 g / cc or more, the internal resistance of the all-solid-state secondary battery can be reduced, and Li penetration through the solid electrolyte layer can be effectively suppressed.

[0263] The oxide solid electrolyte may include, for example, Li 1+x+y Al x Ti 2-x Si y P 3-y O 12 (where 0 < x < 2 and 0 ≤ y < 3), BaTiO3, Pb(Zr,Ti)O3 (PZT), Pb 1-x La x Zr 1-y Ti y O3 (PLZT) (where 0 ≤ x < 1 and 0 ≤ y < 1), Pb(Mg3Nb 2 / 3 )O3-PbTiO3 (PMN-PT), HfO2, SrTiO3, SnO2, CeO2, Na2O, MgO, NiO, CaO, BaO, ZnO, ZrO2, Y2O3, Al2O3, TiO2, SiO2, Li3PO4, Li x Ti y(PO4)3 (where 0 < x < 2 and 0 < y < 3), Li x Al y Ti z (PO4)3 (where 0 < x < 2, 0 < y < 1 and 0 < z < 3), Li 1+x+y (Al, Ga) x (Ti, Ge) 2-x Si y P 3-y O 12 (where 0 ≤ x ≤ 1 and 0 ≤ y ≤ 1), Li x La y TiO3 (where 0 < x < 2 and 0 < y < 3), Li2O, LiOH, Li2CO3, LiAlO2, Li2O - Al2O3 - SiO2 - P2O5 - TiO2 - GeO2, Li 3+x La3M2O 12 (where M = Te, Nb or Zr and 0 ≤ x ≤ 10) or combinations thereof. Oxide - type solid electrolytes are prepared, for example, by sintering or the like.

[0264] Oxide - type solid electrolytes are, for example, selected from Li7La3Zr2O 12 (LLZO) and Li 3+x La3Zr 2-a M a O 12 (LLZO doped with M) (where M = Ga, W, Nb, Ta or Al, 0 < a < 2 and 0 ≤ x ≤ 10) garnet - type solid electrodes.

[0265] For example, polymer solid electrolytes can include a mixture of a lithium salt and a polymer or can include a polymer having ion - conducting functional groups. Polymer solid electrolytes can be, for example, polymer electrolytes in a solid state at a temperature of 25 °C and a pressure of 1 atm. Polymer solid electrolytes can not include, for example, liquids. Polymer solid electrolytes can include polymers, and the polymers can include, for example, polyethylene oxide (PEO), polyvinylidene fluoride (PVDF), poly(vinylidene fluoride - hexafluoropropylene) (PVDF - HFP), PEO, poly(styrene - b - ethylene oxide) (PS - PEO) block copolymer, poly(styrene - butadiene), poly(styrene - isoprene - styrene), poly(styrene - b - divinylbenzene) block copolymer, poly(styrene - ethylene oxide - styrene) block copolymer, poly(styrene sulfonate) (PSS), polyvinyl fluoride (PVF), poly(methyl methacrylate) (PMMA), polyethylene glycol (PEG), polyacrylonitrile (PAN), polytetrafluoroethylene (PTFE), poly(3,4 - ethylenedioxythiophene) (PEDOT), polypyrrole (PPY), PAN, polyaniline, polyacetylene, -ADP, sulfonated poly(ether ether ketone) (SPEEK), sulfonated poly(arylene ether ketone ketone sulfone) (SPAEKKS), sulfonated poly(aryl ether ketone) (SPAEK), poly[bis(benzimidazole benzoisoquinolinone)] (SPBIBI), PSS, lithium 9,10-diphenylanthracene-2-sulfonate (DPASLi + ), or a combination thereof, but one or more embodiments are not limited thereto. Any material can be used as long as it is used in the art for polymer electrolytes. As the lithium salt, any material can be used as long as it can be used as a lithium salt in the art. Lithium salts include, for example, LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiCF3SO3, Li(CF3SO2)2N, LiC4F9SO3, LiAlO2, LiAlCl4, LiN(C x F 2x+1 SO2)(C y F 2y+1 SO2) (where x and y are each natural numbers from 1 to 20), LiCl, LiI, or a mixture thereof. The polymer included in the polymer solid electrolyte can be, for example, a compound including 10 or more, 20 or more, 50 or more, or 100 or more repeating units. The weight-average molecular weight of the polymer included in the polymer solid electrolyte can be, for example, 1000 daltons or greater, 10000 daltons or greater, 100000 daltons or greater, or 1000000 daltons or greater.

[0266] The gel electrolyte can include, for example, a polymer gel electrolyte. The gel electrolyte can have a gel state and not include, for example, a liquid.

[0267] The polymer gel electrolyte may include, for example, a liquid electrolyte and a polymer, or may include an organic solvent and a polymer having an ion-conductive functional group. The polymer gel electrolyte may be, for example, a polymer electrolyte in a gel state at a temperature of 25 °C and a pressure of 1 atm. The polymer gel electrolyte may have, for example, a gel state without including a liquid. The liquid electrolyte used in the polymer gel electrolyte may include, for example: a mixture of an ionic liquid and a lithium salt; a mixture of a lithium salt and an organic solvent; a mixture of an ionic liquid and an organic solvent; or a mixture of a lithium salt, an ionic liquid, and an organic solvent. The polymer used in the polymer gel electrolyte may be selected from the polymers used in solid polymer electrolytes. The organic solvent may be selected from the organic solvents used in liquid electrolytes. The lithium salt may be selected from the lithium salts used in polymer solid electrolytes. An ionic liquid refers to a salt in a liquid state at room temperature or a room-temperature molten salt having a melting point at room temperature or lower and consisting only of ions. The ionic liquid may include, for example, at least one compound, the compound including a) a cation selected from the group consisting of ammonium cations, pyrrolidinium cations, pyridinium cations, pyrimidinium cations, imidazolium cations, piperidinium cations, pyrazolium cations, oxazolium cations, pyridazinium cations, phosphonium cations, sulfonium cations, triazolium cations, and mixtures thereof, and b) selected from BF4 - , PF6 - , AsF6 - , SbF6 - , AlCl4 - , HSO4 - , ClO4 - , CH3SO3 - , CF3CO2 - , Cl - , Br - , I - , BF4 - , SO4 - , CF3SO3 - , (FSO2)2N - , (C2F5SO2)2N - , (C2F5SO2)(CF3SO2)N - and (CF3SO2)2N -At least one of the anions therein. The polymer solid electrolyte can be impregnated in a liquid electrolyte in, for example, a secondary battery to form a polymer gel electrolyte. The polymer gel electrolyte can also include inorganic particles. The polymer included in the polymer gel electrolyte can be, for example, a compound including 10 or more, 20 or more, 50 or more, or 100 or more repeating units. The weight-average molecular weight of the polymer included in the polymer gel electrolyte can be, for example, 500 daltons or greater, 1000 daltons or greater, 10,000 daltons or greater, 100,000 daltons or greater, or 1,000,000 daltons or greater.

[0268] The solid electrolyte layer 30 can be impermeable to lithium polysulfide. Accordingly, a side reaction between the negative electrode layer and lithium polysulfide generated during charging or discharging of the sulfide-based positive electrode active material can be prevented. Accordingly, the cycle characteristics of the all-solid-state secondary battery 1 including the solid electrolyte layer 30 can be improved.

[0269] [Solid electrolyte layer: Binder]

[0270] The solid electrolyte layer 30 can include, for example, a binder. The binder included in the solid electrolyte layer 30 can include, for example, SBR, polytetrafluoroethylene, PVDF, PE, etc., but one or more embodiments are not limited thereto. Any material can be used as long as the material is used as a binder in the art. The binder of the solid electrolyte layer 30 can be the same as or different from the binder included in the positive electrode active material layer 12 and the negative electrode active material layer 22. The binder can be omitted.

[0271] With respect to the total weight of the solid electrolyte layer 30, the content of the binder included in the solid electrolyte layer 30 is in the range of 0.1 wt% to 10 wt%, 0.1 wt% to 5 wt%, 0.1 wt% to 3 wt%, 0.1 wt% to 1 wt%, 0 wt% to 0.5 wt%, or 0 wt% to 0.1 wt%.

[0272] Hereinafter, the all-solid-state secondary battery according to other exemplary embodiments will be described in more detail.

[0273] [All-solid-state secondary battery]

[0274] The all-solid-state secondary battery according to the embodiment includes a positive electrode layer, a negative electrode layer, and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer. Among them, the positive electrode layer includes a positive electrode current collector and a positive electrode active material layer disposed on one or both sides of the positive electrode current collector. The positive electrode active material layer includes a lithium-containing sulfide-based positive electrode active material. The lithium-containing sulfide-based positive electrode active material includes Li2S, a Li2S composite, or a combination thereof. The negative electrode layer includes a negative electrode current collector and a lithium host layer disposed on one side of the negative electrode current collector. The lithium host layer includes a lithium host structure. The lithium host structure includes one or more lithium hosts. The lithium host includes a carbon-based lithium host, a metal-based lithium host, a polymer-based lithium host, or a combination thereof. And the all-solid-state secondary battery includes a first inactive member disposed on the side surface of the negative electrode layer.

[0275] The all-solid-state secondary battery includes a lithium-containing sulfide-based positive electrode active material as the positive electrode active material. Therefore, interruption of the ion and / or electron transport path caused by the volume increase of the sulfide-based positive electrode active material without lithium (e.g., sulfur (S)) during the initial discharge is prevented. Preventing the interruption of the ion and / or electron transport path improves the cycle characteristics of the all-solid-state secondary battery.

[0276] The all-solid-state secondary battery may include a lithium host layer in the negative electrode layer. Therefore, the lithium host can be used as a carrier during the process of depositing lithium metal in the negative electrode layer, thereby suppressing the non-uniformity of lithium precipitation. During the charge / discharge process of the all-solid-state secondary battery, the formation and growth of lithium dendrites and / or dead lithium can be suppressed. Thus, the deterioration of the all-solid-state secondary battery is suppressed, and its cycle characteristics are improved.

[0277] The all-solid-state secondary battery may include a lithium host layer in the negative electrode layer. Therefore, during the charge / discharge process of the all-solid-state secondary battery, a rapid change in the volume of the negative electrode layer can be suppressed. Suppressing the rapid change in the volume of the negative electrode layer suppresses the deterioration of the all-solid-state secondary battery caused by the volume change during the charge / discharge process of the all-solid-state secondary battery and improves its cycle characteristics.

[0278] The all-solid-state secondary battery includes a solid electrolyte layer. Therefore, polysulfides generated during the charge / discharge of the lithium-containing sulfide-based positive electrode active material are prevented from moving to the negative electrode layer. Therefore, side reactions between the polysulfides and the negative electrode active material are suppressed.

[0279] The inactive member is disposed on the side surface of the negative electrode layer, thereby more effectively suppressing a short circuit between the positive electrode and lithium dendrites generated and grown during the charge / discharge of the all-solid-state secondary battery and / or lithium metal melted at high temperature. Thus, a short circuit of the all-solid-state secondary battery is prevented, and its life characteristics are improved.

[0280] Refer to Figures 10 to 17, the all-solid-state secondary battery 1 includes a positive electrode layer 10, a negative electrode layer 20, and a solid electrolyte layer 30 disposed between the positive electrode layer 10 and the negative electrode layer 20. The positive electrode layer 10 includes a positive electrode current collector 11 and a positive electrode active material layer 12 disposed on one or both sides of the positive electrode current collector 11. The positive electrode active material layer 12 includes a lithium-containing sulfide-based positive electrode active material. The lithium-containing sulfide-based positive electrode active material includes Li2S, a Li2S-containing composite, or a combination thereof. The negative electrode layer 20 includes a negative electrode current collector 21 and a lithium host layer (i.e., a negative electrode active material layer) 22 disposed on one side of the negative electrode current collector 21. The lithium host layer 22 includes a lithium host structure. The lithium host structure includes one or more lithium hosts. The lithium host includes a carbon-based lithium host, a metal-based lithium host, a polymer-based lithium host, or a combination thereof. The all-solid-state secondary battery 1 includes a first inactive member 42 disposed on the side surface of the negative electrode layer 20.

[0281] [Negative electrode layer]

[0282] [Negative electrode layer: Lithium host]

[0283] Referring to Figures 10 to 17 , the negative electrode layer 20 includes a lithium host layer 22. The lithium host layer 22 includes a lithium host structure. Since the lithium host layer 22 includes a lithium host structure, lithium in the lithium host layer 22 can precipitate more easily and uniformly.

[0284] The lithium host structure may include, for example, a one-dimensional structure, a two-dimensional structure, a three-dimensional structure, or a combination thereof.

[0285] The one-dimensional structure may include a one-dimensional nanostructure, a one-dimensional microstructure, or a combination thereof. The one-dimensional nanostructure may include, for example, nanofibers, nanotubes, nanorods, or a combination thereof. The one-dimensional microstructure may include, for example, microfibers, microtubes, microrods, or a combination thereof. The lithium host one-dimensional structure may include, for example, a lithium host one-dimensional nanostructure, a lithium host one-dimensional microstructure, or a combination thereof.

[0286] The two-dimensional structure may include, for example, a two-dimensional nanostructure, a two-dimensional microstructure, or a combination thereof. The two-dimensional nanostructure may include, for example, nanosheets, nanoplates, or a combination thereof. The two-dimensional microstructure may include, for example, microsheets, microplates, or a combination thereof. The lithium host two-dimensional structure may include, for example, a lithium host two-dimensional nanostructure, a lithium host two-dimensional microstructure, or a combination thereof.

[0287] The three-dimensional structure may include, for example, a three-dimensional nanostructure, a three-dimensional microstructure, or a combination thereof. The three-dimensional nanostructure may include, for example, nanoparticles, nanocages, nanomatrices, or a combination thereof. The three-dimensional microstructure may include, for example, microparticles, microcages, micromatrices, or a combination thereof. The lithium host three-dimensional structure may include, for example, a lithium host three-dimensional nanostructure, a lithium host three-dimensional microstructure, or a combination thereof.

[0288] The lithium host structure can include, for example, a porous structure, a non-porous structure, or a combination thereof.

[0289] The porous structure can include one or more pores in the structure. The pores can include open pores, closed pores, or a combination thereof. The porous structure can include, for example, a microporous structure including pores with a size of 2 nm or less, a mesoporous structure including pores with a size of 2 nm to 50 nm, a macroporous structure including pores with a size greater than 50 nm, or a combination thereof. The pores included in the macroporous structure can include, for example, pores with a size greater than 50 nm to 500 nm, pores with a size greater than 500 nm to 1 μm, pores with a size greater than 1 μm to 10 μm, pores with a size greater than 10 μm to 50 μm, or a combination thereof. The lithium host structure can include a particulate structure, a sheet structure, a paper structure, a non-woven fabric structure, a woven fabric structure, a foam structure, a reticular structure, or a combination thereof, but one or more embodiments are not limited thereto. Any structure can be used as long as the structure is used as a lithium host structure in the art. The porous structure can have a porosity ratio of 5 vol% to 99 vol%, 10 vol% to 99 vol%, 20 vol% to 99 vol%, or 30 vol% to 99 vol% in the total volume defined by the outer surface of the structure.

[0290] The non-porous structure is a structure that substantially does not include pores in the structure. The non-porous structure can include, for example, non-porous particles. The non-porous structure can have a porosity ratio of 1 vol% or less, 0.5 vol% or less, or 0.1 vol% or less in the total volume defined by the outer surface of the structure.

[0291] The lithium host structure includes one or more lithium hosts. The lithium host structure can be composed of, for example, one lithium host. The lithium host structure can be composed of, for example, a combination of multiple lithium hosts.

[0292] The lithium host includes, for example, a carbon-based lithium host, a metal-based lithium host, a polymer-based lithium host, or a combination thereof.

[0293] The carbon-based lithium host includes, for example, amorphous carbon, crystalline carbon, porous carbon, non-porous carbon, or a combination thereof. The carbon-based lithium host can include, for example, CB, AB, FB, KB, graphene, GO, rGO, carbon fiber, CNT, carbon nanobelt, carbon paper, carbon sheet, carbon foam, or a combination thereof. The carbon-based lithium host can include, for example, carbon fiber cloth, carbonized metal-organic framework (MOF), carbonized porous MOF, graphene foam, CNF, hollow carbon nanocube, carbon core / shell array, porous carbon sheet, carbon rod array, three-dimensional (3D) nanoporous graphene, wrinkled graphene sphere, graphene sphere containing metal oxide particles, carbon particle, carbon fiber skeleton, carbon matrix, or a combination thereof.

[0294] The carbon-based lithium host may further include, for example, a coating provided on the carbon-based lithium host or a dopant doped into the carbon-based lithium host. The carbon-based lithium host may further include a coating and / or a dopant, thereby improving the mechanical durability and electrochemical stability of the carbon-based lithium host, the reversibility of the lithium precipitation reaction, etc. The coating provided on the carbon-based lithium host may be, for example, a lithiophilic layer, a protective layer, or a composite layer thereof. The coating may have a single-layer structure or a multi-layer structure.

[0295] The lithiophilic layer may be provided on the carbon-based lithium host, thereby improving the lithiophilicity of the carbon-based lithium host, and thus improving the reversibility of the lithium metal precipitation reaction on the carbon-based lithium host. Thereby, the cycle characteristics of the all-solid-state secondary battery including the carbon-based lithium host can be improved. The lithiophilic layer may include, for example, a lithiophilic material. The lithiophilic material may include, for example, a lithiophilic metal, a lithiophilic metal oxide, a lithiophilic metal phosphate, a lithiophilic metal nitride, a lithiophilic metal oxynitride, a lithiophilic metal carbide, a lithiophilic MOF, a lithiophilic metal chalcogenide, or a combination thereof. The lithiophilic material may include, for example, gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), zinc (Zn), or an alloy thereof. The lithiophilic metal oxide may include, for example, gold oxide, platinum oxide, palladium oxide, silicon oxide, silver oxide, aluminum oxide, bismuth oxide, tin oxide, manganese oxide, zinc oxide, or a combination thereof. The lithiophilic metal oxide may include, for example, ZnO, SiO2, MnO2, Co3O4, SnO2, or a combination thereof. The lithiophilic metal nitride may include, for example, titanium nitride, cobalt nitride, or a combination thereof. The lithiophilic metal nitride may include, for example, TiN, Co4N, or a combination thereof. The lithiophilic metal carbide may include, for example, lithium carbide, titanium carbide, or a combination thereof. The lithiophilic metal carbide may include, for example, Li6C, TiC, or a combination thereof. In addition, the metal-based lithium host described below may be used as a lithiophilic material.

[0296] The protective layer may be provided on the carbon-based lithium host, thereby improving the mechanical durability and electrochemical stability of the carbon-based lithium host. Thereby, the cycle characteristics of the all-solid-state secondary battery including the carbon-based lithium host can be improved. The protective layer may include, for example, a protective material. The protective material may include, for example, an organic material, an inorganic material, an organic-inorganic composite material, or a combination thereof. The organic material may be, for example, a polymer. The inorganic material may be, for example, a metal oxide. The organic-inorganic composite material may be, for example, MOF.

[0297] The dopant may be doped into the lithium host. The dopant may be doped into the lithium host to obtain a doped lithium host. The lithiophilicity of the doped lithium host can be improved. The dopant may include, for example, a heteroatom. The heteroatom may include, for example, nitrogen (N), oxygen (O), phosphorus (P), boron (B), sulfur (S), fluorine (F), chlorine (Cl), bromine (Br), germanium (Ge), gallium (Ga), or a combination thereof.

[0298] The lithium-like metal host can include, for example, metals, metal oxides, metal phosphates, metal nitrides, metal oxynitrides, metal carbides, MOFs, metal chalcogenides, or combinations thereof. The metal can include, for example, copper (Cu), nickel (Ni), stainless steel (SUS), titanium (Ti), iron (Fe), cobalt (Co), or alloys thereof. The metal oxides can include, for example, copper oxide, zinc oxide, nickel oxide, titanium oxide, iron oxide, cobalt oxide, ruthenium oxide, iridium oxide, platinum oxide, manganese oxide, tin oxide, indium oxide, or combinations thereof. The metal phosphates can include, for example, copper phosphate, nickel phosphate, titanium phosphate, iron phosphate, cobalt phosphate, ruthenium phosphate, iridium phosphate, platinum phosphate, manganese phosphate, tin phosphate, indium phosphate, or combinations thereof. The metal nitrides can include, for example, titanium nitride, tungsten nitride, thallium nitride, titanium aluminum nitride, thallium silicon nitride, titanium silicon nitride, ruthenium titanium nitride, or combinations thereof. The metal oxynitrides can include, for example, copper oxynitride, nickel oxynitride, titanium oxynitride, iron oxynitride, cobalt oxynitride, ruthenium oxynitride, iridium oxynitride, platinum oxynitride, manganese oxynitride, tin oxynitride, indium oxynitride, or combinations thereof. The metal carbides can include, for example, copper carbide, nickel carbide, titanium carbide, iron carbide, cobalt carbide, ruthenium carbide, iridium carbide, platinum carbide, manganese carbide, tin carbide, indium carbide, or combinations thereof. The MOFs can include, for example, Co-embedded N-doped carbon (Co-NC, ZIF-67), Zn-embedded N-doped carbon (Zn-NC, ZIF-8), or combinations thereof. The metal chalcogenides can include, for example, molybdenum disulfide, molybdenum diselenide, molybdenum ditelluride, tungsten disulfide, tungsten diselenide, tungsten ditelluride, or combinations thereof.

[0299] The lithium-like metal host can also include, for example, a coating provided on the lithium-like metal host or a dopant doped into the lithium-like metal host. The lithium-like metal host can also include a coating and / or a dopant, thereby improving the mechanical durability and electrochemical stability of the lithium-like metal host, the reversibility of the lithium precipitation reaction, and the like. The coating provided on the lithium-like metal host can be, for example, a lithiophilic layer, a protective layer, or a composite layer thereof. The coating can have a single-layer structure or a multi-layer structure.

[0300] The lithiophilic layer can be provided on the lithium-like metal host, thereby improving the lithiophilicity of the lithium-like metal host, and thus improving the reversibility of the lithium metal precipitation reaction on the lithium-like metal host. Thereby, the cycle characteristics of the all-solid-state secondary battery including the lithium-like metal host can be improved. The lithiophilic layer can include, for example, lithiophilic materials. The lithiophilic materials can include, for example, lithiophilic metals, lithiophilic metal oxides, lithiophilic metal phosphates, lithiophilic metal nitrides, lithiophilic metal oxynitrides, lithiophilic metal carbides, lithiophilic MOFs, lithiophilic metal chalcogenides, or combinations thereof. The specific lithiophilic materials provided on the lithium-like metal host can be selected from the above lithiophilic materials provided on the carbon-like lithium host.

[0301] A protective layer can be provided on a metal-based lithium host, thereby improving the mechanical durability and electrochemical stability of the metal-based lithium host. Thereby, the cycle characteristics of an all-solid-state secondary battery including the metal-based lithium host can be improved. The protective layer can include, for example, a protective material. The protective material can include, for example, an organic material, an inorganic material, an organic-inorganic composite material, or a combination thereof. The organic material can be, for example, a polymer. The inorganic material can be, for example, a metal oxide.

[0302] A dopant can be doped into the metal-based lithium host. The dopant can be doped into the metal-based lithium host to obtain a doped metal-based lithium host. The lithiophilicity of the doped metal-based lithium host can be improved. The dopant can be, for example, a p-type dopant or an n-type dopant. The dopant can include, for example, nitrogen (N), oxygen (O), phosphorus (P), boron (B), sulfur (S), fluorine (F), chlorine (Cl), bromine (Br), germanium (Ge), gallium (Ga), or a combination thereof.

[0303] The polymer-based lithium host can include, for example, an insulating polymer, an ion-conductive polymer, an electron-conductive polymer, or a combination thereof. The insulating polymer includes, for example, PE, PP, polystyrene, poly(N-vinylcarbazole), polyvinylphenol, PI, polyamide, or cellulose. The ion-conductive polymer is a polymer including an ion-conductive repeating unit in the main chain or side chain. The ion-conductive repeating unit can be a unit having ion conductivity and can be, for example, an alkylene oxide unit or a hydrophilic unit. The ion-conductive polymer can include, for example, an ether monomer, an acrylic monomer, a methacrylic monomer, a siloxane monomer, or a combination thereof as the ion-conductive repeating unit. Examples of the ion-conductive polymer can include PEO, PP oxide, polymethyl methacrylate, polyethyl methacrylate, polydimethylsiloxane, polyacrylic acid, polymethacrylic acid, poly(methyl acrylate), poly(ethyl acrylate), poly(2-ethylhexyl acrylate), poly(butyl methacrylate), poly(2-ethylhexyl methacrylate), poly(decyl acrylate), poly(ethylene vinyl acetate), or a combination thereof. Examples of the ion-conductive polymer can include PEO, poly(vinyl alcohol) (PVA), poly(vinyl pyrrolidone) (PVP), poly(vinyl sulfone), or a combination thereof. Specifically, examples of the ion-conductive polymer include PSS, PVDF-HFP copolymer, PVF, PVDF, PMMA, PEO, PEG, PAN, polytetrafluoroethylene (PTFE), PEDOT, PPY, polyaniline, and polyacetylene. The ion-conductive polymer can include a polar functional group. Examples of the ion-conductive polymer including a polar functional group include Nafion, Aquivion, Flemion, Gore, Aciplex, Morgane ADP, SPEEK, SPAEKKS, SPAEK, SPBIBI, PSS, DPALi +etc. Examples of electronically conductive polymers include polyacetylene, polythiophene, PPY, poly(p-phenylene), poly(phenylene vinylene), poly(phenylene sulfide), polyaniline, etc.

[0304] The polymer-based lithium host may also include, for example, a coating provided on the polymer-based lithium host or polar functional groups provided on the surface of the polymer-based lithium host. The polymer-based lithium host may also include a coating and / or polar functional groups, thereby improving the mechanical durability and electrochemical stability of the polymer-based lithium host, the reversibility of the lithium precipitation reaction, etc.

[0305] The coating provided on the polymer-based lithium host may be, for example, a lithiumophilic layer, a protective layer, or a composite layer thereof. The coating may have a single-layer structure or a multi-layer structure.

[0306] The lithiumophilic layer may be provided on the polymer-based lithium host, thereby improving the lithiumophilicity of the polymer-based lithium host, and thus improving the reversibility of the lithium metal precipitation reaction on the polymer-based lithium host. Thereby, the cycle characteristics of the all-solid-state secondary battery including the polymer-based lithium host can be improved. The lithiumophilic layer may include, for example, a lithiumophilic material. The lithiumophilic material may include, for example, a lithiumophilic metal, a lithiumophilic metal oxide, a lithiumophilic metal phosphate, a lithiumophilic metal nitride, a lithiumophilic metal oxynitride, a lithiumophilic metal carbide, a lithiumophilic MOF, a lithiumophilic metal chalcogenide, or a combination thereof. The specific lithiumophilic material provided on the polymer-based lithium host may be selected from the lithiumophilic materials provided on the carbon-based lithium host described above.

[0307] The protective layer may be provided on the polymer-based lithium host, thereby improving the mechanical durability and electrochemical stability of the polymer-based lithium host. Thereby, the cycle characteristics of the all-solid-state secondary battery including the polymer-based lithium host can be improved. The protective layer may include, for example, a protective material. The protective material may include, for example, an organic material, an inorganic material, an organic-inorganic composite material, or a combination thereof. The organic material may be, for example, a polymer different from the polymer-based lithium host. The inorganic material may be, for example, a metal oxide.

[0308] The polar functional groups provided on the surface of the polymer-based lithium host may include, for example, a hydroxyl group, a nitrile group, or a combination thereof, but one or more embodiments are not limited thereto. Any material may be used as long as the material is used as a polar functional group in the art.

[0309] The lithium host layer may include a lithium host, and the lithium host may include, for example, a conductive lithium host, a non-conductive lithium host, or a combination thereof. The conductive lithium host is a lithium host having electronic conductivity. The electronic conductivity of the conductive lithium host may be, for example, 1.0×10 3 S / m or greater, 1.0×10 4 S / m or greater, or 1.0×10 5S / m or greater. The lithium host layer may include a conductive lithium host, and thus the internal resistance of the all-solid-state secondary battery including the lithium host layer can be reduced. The conductive lithium host may be, for example, a carbon-based lithium host, a metal-based lithium host, etc. The non-conductive lithium host is a lithium host that does not have electronic conductivity. The electronic conductivity of the non-conductive lithium host may be, for example, 1.0×10 -3 S / m or less, 1.0×10 -4 S / m or less, or 1.0×10 -5 S / m or less. The lithium host layer may include a non-conductive lithium host, and thus the structural stability of the all-solid-state secondary battery including the lithium host layer can be improved. The non-conductive lithium host may be, for example, an insulating polymer lithium host.

[0310] The lithium host layer may include a lithium host, and the lithium host may include, for example, an electrochemically inert lithium host, an electrochemically active lithium host, or a combination thereof. The electrochemically inert lithium host is a lithium host that does not react with lithium to form a compound and acts as a conductor for transporting electrons and / or an acceptor for accommodating precipitated lithium. Since the lithium host layer includes the electrochemically inert lithium host, the all-solid-state secondary battery can be more effectively prevented from deteriorating due to volume change and / or physical property change of the lithium host during charge / discharge. The electrochemically inert lithium host may be, for example, a carbon-based lithium host such as amorphous carbon. The electrochemically active lithium host is a lithium host that reacts with lithium to form an alloy or a compound. The lithium host layer may include the electrochemically active lithium host, and thus uneven lithium precipitation can be more effectively prevented, further improving the cycle characteristics of the all-solid-state secondary battery. The electrochemically active lithium host may be a metal-based lithium host, such as a metal oxide capable of forming an alloy or a compound with lithium.

[0311] [Negative electrode layer: Binder]

[0312] The binder included in the lithium host layer 22 is, for example, SBR, PTFE, PVDF, PE, vinylidene fluoride / hexafluoropropylene copolymer, PAN, polymethyl methacrylate, etc., but one or more embodiments are not necessarily limited thereto. Any material can be used as long as the material is used as a binder in the art. The binder may be provided as a single binder or a plurality of different binders.

[0313] The binder can bond a plurality of lithium hosts to each other to form a lithium host structure. When the binder is not included in the lithium host layer 22, it may be difficult for the lithium host structure included in the lithium host layer 22 to maintain mechanical stability. That is, during the charge / discharge process of the all-solid-state secondary battery, the lithium host structure may collapse to form a lithium metal layer, and lithium dendrites may grow from the lithium metal layer to the positive electrode, which may cause a short circuit.

[0314] [Negative electrode layer: Intermediate layer]

[0315] The all-solid-state secondary battery 1 may further include, for example, an intermediate layer (not shown) disposed between the lithium host layer 22 and the solid electrolyte layer 30 and / or between the lithium host layer 22 and the negative electrode current collector 21.

[0316] The intermediate layer may be disposed between the lithium host layer 22 and the solid electrolyte layer 30, thereby increasing the bonding force between the lithium host layer 22 and the solid electrolyte. Therefore, during the charge / discharge process of the all-solid-state secondary battery 1, the structural stability of the lithium host layer 22 can be improved. In addition, side reactions between the solid electrolyte layer 30 and the lithium metal precipitated in the lithium host layer 22 during the charge / discharge process of the all-solid-state secondary battery 1 can be suppressed. Therefore, the cycle characteristics of the all-solid-state secondary battery 1 including the intermediate layer can be further improved.

[0317] The intermediate layer may be disposed between the lithium host layer 22 and the negative electrode current collector 21, thereby increasing the bonding force between the lithium host layer 22 and the negative electrode current collector 21. Therefore, during the charge / discharge process of the all-solid-state secondary battery 1, the structural stability of the lithium host layer 22 can be improved. Therefore, the cycle characteristics of the all-solid-state secondary battery 1 including the intermediate layer can be improved.

[0318] The intermediate layer may include a binder. The binder included in the intermediate layer may include, for example, SBR, PTFE, PVDF, PE, vinylidene fluoride / hexafluoropropylene copolymer, PAN, polymethyl methacrylate, etc., but one or more embodiments are not necessarily limited thereto. Any material may be used as long as the material is used as a binder in the art. The binder may be provided as a single binder or a plurality of different binders. The binder may be, for example, a fluorine-based binder. The fluorine-based binder may be, for example, PVDF.

[0319] [Negative electrode layer: Other additives]

[0320] The lithium host layer 22 may further include additives used in the all-solid-state secondary battery 1 according to the related art, such as fillers, coating agents, dispersants, and ion conductive aids.

[0321] [Negative electrode layer: Lithium host layer]

[0322] The ratio B / A of the initial charge capacity B of the lithium host layer 22 to the initial charge capacity A of the positive electrode active material layer is, for example, in the range of 0 to 0.45. The initial charge capacity of the positive electrode active material layer 12 can be determined from the first open circuit voltage to the maximum charge voltage vs. Li / Li + Determined. The initial charge capacity of the lithium host layer 22 is determined from the second open circuit voltage to 0.01V vs. Li / Li + Determined.

[0323] The maximum charging voltage is determined by the type of the positive electrode active material. The maximum charging voltage can be, for example, 1.5V, 2.0V, 2.5V, 3.0V, 3.5V, 4.0V, 4.2V, 4.3V. For example, the maximum charging voltage of Li2S or a Li2S composite can be 2.5V vs. Li / Li + For example, the maximum charging voltage of Li2S or a Li2S composite can be 3.0V vs. Li / Li + The ratio B / A of the initial charging capacity B of the lithium host layer 22 to the initial charging capacity A of the positive electrode active material layer is, for example, in the range of greater than 0 to 0.3, 0.01 to 0.2, or 0.05 to 0.1. The initial charging capacity of the lithium host layer 22 is the charging capacity of the lithium host itself in the lithium host layer 22. That is, the initial charging capacity of the lithium host layer 22 is the charging capacity before lithium metal is deposited in the lithium host layer 22. In the lithium host layer 22 including an electrochemically inert lithium host, the initial charging capacity of the lithium host layer 22 is, for example, 0. For example, in the lithium host layer including an electrochemically inert carbon paper, the initial charging capacity is 0. In the lithium host layer including an electrochemically active lithium host, the initial charging capacity is, for example, in the range of greater than 0 to 0.3, 0.01 to 0.2, or 0.05 to 0.1. For example, in the lithium host layer including an electrochemically active porous foam graphite, the initial charging capacity is, for example, in the range of greater than 0 to 0.45. When the ratio B / A of the initial charging capacity B of the lithium host layer 22 to the initial charging capacity A of the positive electrode active material layer exceeds 0.45, the ratio of the lithium absorbed into the lithium host itself may become too high compared to the lithium deposited in the lithium host layer 22, and thus the energy density of the all-solid-state secondary battery may decrease.

[0324] The initial charging capacity (mAh) of the positive electrode active material layer 12 is obtained by multiplying the charging specific capacity (mAh / g) of the positive electrode active material by the mass (g) of the positive electrode active material in the positive electrode active material layer 12. When various types of positive electrode active materials are used, the value of charging specific capacity × mass is calculated for each positive electrode active material, and the sum of the values is the initial charging capacity of the positive electrode active material layer 12. The initial charging capacity of the lithium host layer 22 is calculated in the same manner. The initial charging capacity of the lithium host layer 22 is obtained by multiplying the charging specific capacity (mAh / g) of the lithium host by the mass of the lithium host in the lithium host layer 22. When various types of lithium hosts are used, the value of charging specific capacity × mass is calculated for each lithium host, and the sum of the values is the initial charging capacity of the lithium host layer 22. The charging specific capacity of each of the positive electrode active material and the lithium host can be measured by using an all-solid-state half-cell with lithium metal as the counter electrode. The initial charging capacity of each of the positive electrode active material layer 12 and the lithium host layer 22 can be measured by using an all-solid-state half-cell at a constant current density (for example, 0.1 mA / cm 2) directly measured. Measurements can be performed on the positive electrode at an operating voltage from the first OCV up to a maximum charging voltage of, for example, 3.0 V (vs. Li / Li + ) and on the negative electrode at an operating voltage from the second OCV up to 0.01 V of the negative electrode (e.g., lithium metal). For example, a all-solid-state half-cell including a positive electrode active material layer can be charged from the first OCV to 3.0 V at a constant current of 0.1 mA / cm 2 , and a all-solid-state half-cell including a first negative electrode active material layer can be charged from the second OCV to 0.01 V at a constant current of 0.1 mA / cm 2 . The current density during constant current charging can be, for example, 0.2 mA / cm 2 or 0.5 mA / cm 2 . A all-solid-state half-cell including a positive electrode active material layer can be charged, for example, from the first OCV to 2.5 V, 2.0 V, 3.5 V, or 4.0 V. The maximum charging voltage of the positive electrode active material layer can be determined by the maximum voltage of a battery that satisfies the safety conditions of JIS C8712:2015 of the Japanese Standards Association. When the initial charging capacity of the lithium host layer 22 is 0, the lithium host only serves as a carrier for accommodating the precipitated lithium. When the initial charging capacity of the lithium host layer exceeds 0, the lithium host serves as both a negative electrode active material and a carrier for accommodating the precipitated lithium.

[0325] The thickness of the lithium host layer 22 can be, for example, 10% or more, 30% or more, 40% or more, 50% or more, 60% or more, 70% or more, 80% or more, or 90% or more of the thickness of the positive electrode active material layer. The thickness of the lithium host layer can be, for example, 100% or less, 99% or less, 98% or less, or 97% or less of the thickness of the positive electrode active material layer. The thickness of the lithium host layer can be, for example, in the range of 10% to 100%, 30% to 100%, 40% to 100%, 50% to 100%, 60% to 99%, 70% to 98%, or 80% to 97% of the thickness of the positive electrode active material layer. The lithium host layer can have a thickness within such a range, and thus the cycle characteristics of the all-solid-state secondary battery can be further improved. The thickness of the lithium host layer 22 can be, for example, 10% or more, 30% or more, 40% or more, 50% or more, 60% or more, 70% or more, or 90% or more of the thickness of the solid electrolyte layer. The thickness of the lithium host layer can be, for example, 100% or less, 99% or less, 98% or less, or 97% or less of the thickness of the solid electrolyte layer. The thickness of the lithium host layer can be, for example, in the range of 10% to 100%, 30% to 100%, 40% to 100%, 50% to 100%, 60% to 99%, 70% to 98%, or 80% to 97% of the thickness of the solid electrolyte layer. The lithium host layer can have a thickness within such a range, and thus the cycle characteristics of the all-solid-state secondary battery can be further improved. The thickness of the lithium host layer 22 is, for example, in the range of 20 μm to 300 μm, 30 μm to 300 μm, 50 μm to 200 μm, or 100 μm to 200 μm. When the lithium host layer 22 is too thin, the content of lithium metal accommodated in the lithium host layer 22 may be too low, resulting in too low a capacity of the all-solid-state secondary battery. When the thickness of the lithium host layer 22 is too large, the energy density of the all-solid-state secondary battery 1 may decrease.

[0326] The lithium host layer may further include pores. The lithium host layer may include a lithium host structure composed of one or more lithium hosts and pores.

[0327] The assembled solid-state secondary battery 1 or the partially or fully discharged solid-state secondary battery 1 may include pores (e.g., in the lithium host layer 22). The fully charged all-solid-state secondary battery 1 may not include pores (e.g., in the lithium host layer 22). The pores may include, for example, first pores provided in the lithium host, interstitial second pores between multiple lithium hosts, or a combination thereof. The multiple lithium hosts forming the second pores may each be, for example, a pore-free structure. The first pores may include pores provided, for example, in CNTs. The second pores may include pores formed by, for example, multiple CNFs, multiple CNTs, multiple graphene, etc. The lithium host structure may include the first pores, the second pores, or a combination thereof. A sheet structure, a paper structure, a nonwoven fabric structure, a woven fabric structure, a foam structure, a mesh structure, etc. may include, for example, the first pores, the second pores, or a combination thereof. For example, carbon paper composed of multiple carbon fibers may include second pores provided between the multiple carbon fibers constituting the carbon paper. For example, a carbon sheet composed of multiple hollow carbon fibers may include all of the first pores provided in the hollow carbon fibers and the second pores provided between the multiple hollow carbon fibers. The volume of the pores in the lithium host layer may be in the range of 1 vol% to 99 vol%, 5 vol% to 95 vol%, 10 vol% to 90 vol%, 20 vol% to 80 vol%, or 30 vol% to 70 vol% of the total volume of the lithium host layer. The volume of the lithium host layer may be calculated by the product of the thickness and area of the lithium host layer.

[0328] In the lithium host layer, after the all-solid-state secondary battery is charged, lithium metal or a lithium alloy may be provided in some or all of the pores. Since the lithium metal or the lithium alloy can be accommodated in the pores included in the lithium host layer, volume change of the lithium host layer can be suppressed during the charge or discharge process of the all-solid-state secondary battery. Therefore, since volume change (e.g., thickness change of the negative electrode layer) of the negative electrode layer can be suppressed during the charge or discharge process of the all-solid-state secondary battery, the structural stability of the all-solid-state secondary battery can be improved, thereby more effectively suppressing deterioration of the all-solid-state secondary battery.

[0329] [Negative electrode layer: Negative electrode current collector]

[0330] The negative electrode current collector 21 is composed of a material that does not react with lithium (i.e., does not form both an alloy and a compound with lithium). The materials constituting the negative electrode current collector 21 include, for example, copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), and nickel (Ni), but one or more embodiments are not necessarily limited thereto. Any material may be used as long as the material is used as an electrode current collector in the art. The negative electrode current collector 21 may be composed of one of the above metals or an alloy or a coating material of two or more types of the above metals. The negative electrode current collector 21 is in the form of a plate or a foil, for example.

[0331] For example, although not shown in the drawings, the all-solid-state secondary battery 1 may further include a thin film on one side of the negative electrode current collector 21, the thin film including an element capable of forming an alloy with lithium. The thin film may be disposed between the negative electrode current collector 21 and the lithium matrix layer 22. The thin film may include, for example, an element capable of forming an alloy with lithium. Examples of the element capable of forming an alloy with lithium include gold, silver, zinc, tin, indium, silicon, aluminum, bismuth, etc., but one or more embodiments are not necessarily limited thereto. Any material may be used as long as the material can form an alloy with lithium in the art. The thin film is composed of one of such metals or an alloy of various of such metals. The thin film may be disposed on one side of the negative electrode current collector 21 such that, for example, the second negative electrode active material layer in the form of a precipitate deposited between the thin film and the lithium matrix layer 22 can be further flattened, and the cycle characteristics of the all-solid-state secondary battery 1 can be further improved.

[0332] The thickness of the thin film is, for example, in the range of 1 nm to 800 nm, 10 nm to 700 nm, 50 nm to 600 nm, or 100 nm to 500 nm. When the thickness of the thin film is less than 1 nm, the thin film may be difficult to function. When the film is too thick, the thin film itself may absorb lithium, so the amount of lithium precipitated in the negative electrode may decrease, which may reduce the energy density of the all-solid-state secondary battery 1 and may deteriorate the cycle characteristics of the all-solid-state secondary battery 1. The thin film may be disposed on the negative electrode current collector 21 by, for example, vacuum deposition, sputtering, plating, etc., but one or more embodiments are not necessarily limited to such methods. Any method may be used as long as the thin film can be formed by the method in the art.

[0333] The negative electrode current collector 21 may include, for example, a base film and a metal layer disposed on one or both sides of the base film. The base film may include, for example, a polymer. The polymer may include, for example, PET, PE, PP, PBT, PI, or a combination thereof. The metal layer may include, for example, indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), or an alloy thereof. Since the negative electrode current collector 21 has such a structure, the weight of the electrode can be reduced, and thus the energy density of the all-solid-state secondary battery can be improved.

[0334] [Negative electrode layer: First non-active member]

[0335] Refer to Figure 10 , Figure 11 , Figure 14 and Figure 15 , the negative electrode layer 20 includes a negative electrode current collector 21 and a lithium matrix layer 22 disposed on one side of the negative electrode current collector 21. The first non-active member 42 is disposed on the side surface of the negative electrode layer 20.

[0336] The first inactive member 42 is disposed on the side of the lithium host layer 22 and is disposed between the solid electrolyte layer 30 and the negative electrode current collector 21 opposite to the solid electrolyte layer 30. The first inactive member 42 may not be disposed on the side of the negative electrode current collector 21. Refer to Figure 12 and Figure 13 , the first inactive member 42 is disposed on the side of the lithium host layer 22 and the side of the negative electrode current collector 21. The first inactive member 42 is included to more effectively prevent a short circuit between the positive electrode layer 10 and the lithium metal precipitated in the lithium host layer 22 during charge / discharge of the all-solid-state secondary battery 1, thereby improving the cycle characteristics of the all-solid-state secondary battery 1. The first inactive member 42 is included to prevent cracks in the solid electrolyte layer 30 during the manufacture and / or charge / discharge of the all-solid-state secondary battery 1, thereby improving the cycle characteristics of the all-solid-state secondary battery 1. In the all-solid-state secondary battery 1 that does not include the first inactive member 42, uneven pressure is applied to the solid electrolyte layer 30 in contact with the negative electrode layer 20 during the manufacture and / or charge / discharge of the all-solid-state secondary battery 1, thereby causing cracks in the solid electrolyte layer 30, and the lithium metal grows through the cracks, thereby increasing the possibility of a short circuit.

[0337] Refer to Figure 10 、 Figure 11 、 Figure 14 and Figure 15 , in the all-solid-state secondary battery 1, the thickness T2 of the first inactive member 42 is substantially equal to the thickness T1 of the lithium host layer 22. Since the sum of the thickness T2 of the first inactive member 42 and the thickness T4 of the negative electrode current collector 21 is substantially equal to the thickness T3 of the negative electrode layer 20, uniform pressure is applied between the negative electrode layer 20 and the solid electrolyte layer 30, and the negative electrode layer 20 and the solid electrolyte layer 30 are in sufficient close contact with each other, thereby reducing the interfacial resistance between the negative electrode layer 20 and the solid electrolyte layer 30. In addition, during the process of pressing and manufacturing the all-solid-state secondary battery 1, the solid electrolyte layer 30 is sufficiently sintered, thereby reducing the internal resistance of the solid electrolyte layer 30 and the all-solid-state secondary battery 1 including it.

[0338] Refer to Figure 12 and Figure 13, in the all-solid-state secondary battery 1, the thickness T2 of the first non-active member 42 is greater than the thickness T1 of the lithium host layer 22. In the all-solid-state secondary battery 1, the thickness T2 of the first non-active member 42 is substantially equal to the thickness T3 of the negative electrode layer 20. Since the thickness T2 of the first non-active member 42 is substantially equal to the thickness T3 of the negative electrode layer 20, a uniform pressure is applied between the negative electrode layer 20 and the solid electrolyte layer 30, and the negative electrode layer 20 and the solid electrolyte layer 30 are in sufficient close contact with each other, thereby reducing the interfacial resistance between the negative electrode layer 20 and the solid electrolyte layer 30. In addition, during the process of pressing and manufacturing the all-solid-state secondary battery 1, the solid electrolyte layer 30 is sufficiently sintered, thereby reducing the internal resistance of the solid electrolyte layer 30 and the all-solid-state secondary battery 1 including it.

[0339] Referring to Figures 10 to 15 , the first non-active member 42 surrounds the side surface of the negative electrode layer 20 and contacts the solid electrolyte layer 30. The first non-active member 42 surrounds the side surface of the negative electrode layer 20 and contacts the solid electrolyte layer 30, thereby effectively suppressing cracks in the solid electrolyte layer 30, which are caused by the pressure difference during the pressing process in the portion of the solid electrolyte layer 30 that does not contact the positive electrode layer 10. The first non-active member 42 surrounds the side surface of the negative electrode layer 20 and is separated from the positive electrode layer 10. The first non-active member 42 surrounds the side surface of the negative electrode layer 20, contacts the solid electrolyte layer 30, and is separated from the positive electrode layer 10. Therefore, the possibility of short circuit due to physical contact between the positive electrode layer 10 and the lithium host layer 22 or due to overcharging of lithium is suppressed. Referring to Figure 12 and Figure 13 , the first non-active member 42 is provided on both the side surface of the lithium host layer 22 and the side surface of the negative electrode current collector 21, thereby more effectively suppressing the possibility of short circuit due to contact between the negative electrode current collector 21 and the positive electrode layer 10.

[0340] Referring to Figures 10 to 17 , the first non-active member 42 (42a or 42b) extends from the side surface of the lithium host layer 22 or the negative electrode layer 20 to the end of the solid electrolyte layer 30. The first non-active member 42 extends to the end of the solid electrolyte layer 30, thereby suppressing cracks generated at the end of the solid electrolyte layer 30. The end of the solid electrolyte layer 30 is the outermost portion in contact with the side surface of the solid electrolyte layer 30. The first non-active member 42 extends to the outermost portion in contact with the side surface of the solid electrolyte layer 30. The first non-active member 42 is separated from the positive electrode layer 10. The first non-active member 42 extends to the end of the solid electrolyte layer 30 but does not contact the positive electrode layer 10. The first non-active member 42 fills, for example, the space extending from the side surface of the lithium host layer 22 or the negative electrode layer 20 to the end of the solid electrolyte layer 30.

[0341] Referring toFigures 10 to 15 The width W2 of the first inactive member 42 extending from the side surface of the lithium host layer 22 or the negative electrode layer 20 to the end portion of the solid electrolyte layer 30 is, for example, in the range of 1% to 30%, 1% to 25%, 1% to 20%, 1% to 15%, 1% to 10%, or 1% to 5% of the width W1 between one side of the lithium host layer 22 and the other side opposite to the one side. When the width W2 of the first inactive member 42 is excessively wide, the energy density of the all-solid-state secondary battery 1 decreases. When the width W2 of the first inactive member 42 is too narrow, it may be difficult to prevent a short circuit between the negative electrode layer 20 and the positive electrode layer 10.

[0342] The area S1 of the lithium host layer 22 or the negative electrode layer 20 is smaller than the area S3 of the solid electrolyte layer 30 in contact with the negative electrode layer 20. The first inactive member 42 is disposed to surround the side surface of the lithium host layer 22 or the negative electrode layer 20 to compensate for the area difference between the lithium host layer 22 or the negative electrode layer 20 and the solid electrolyte layer 30. The area S2 of the first inactive member 42 compensates for the difference between the area S1 of the lithium host layer 22 or the negative electrode layer 20 and the area S3 of the solid electrolyte layer 30, thereby effectively suppressing cracks in the solid electrolyte layer 30 caused by a pressure difference during the pressing process. For example, the sum of the area S1 of the lithium host layer 22 or the negative electrode layer 20 and the area S2 of the first inactive member 42 is substantially equal to the area S3 of the solid electrolyte layer 30.

[0343] The area S1 of the lithium host layer 22 or the negative electrode layer 20 is, for example, less than 100%, 99% or less, 98% or less, 97% or less, 96% or less, or 95% or less of the area S3 of the solid electrolyte layer 30. The area S1 of the negative electrode layer 20 is, for example, in the range of 50% to less than 100%, 50% to 99%, 55% to 98%, 60% to 97%, 70% to 96%, 80% to 95%, 85% to 95% of the area S3 of the solid electrolyte layer 30.

[0344] When the area S1 of the lithium host layer 22 or the negative electrode layer 20 is greater than or equal to the area S3 of the solid electrolyte layer 30, the possibility of a short circuit due to physical contact between the positive electrode layer 10 and the lithium host layer 22 or the possibility of a short circuit due to overcharging increases. The area S1 of the lithium host layer 22 or the negative electrode layer 20 is, for example, substantially equal to the area of the negative electrode current collector 21.

[0345] The area S2 of the first inactive member 42 is, for example, 50% or less, 40% or less, 30% or less, 20% or less, or 10% or less of the area S1 of the lithium host layer 22 or the negative electrode layer 20. The area S2 of the first inactive member 42 is, for example, in the range of 1% to 50%, 5% to 40%, 5% to 30%, 5% to 20%, or 5% to 15% of the area S1 of the lithium host layer 22 or the negative electrode layer 20.

[0346] The area S1 of the lithium host layer 22 or the negative electrode layer 20 is smaller than the area S4 of the positive electrode current collector 11. The area S1 of the lithium host layer 22 or the negative electrode layer 20 is, for example, less than 100%, 99% or less, 98% or less, 97% or less, 96% or less, or 95% or less of the area S4 of the positive electrode current collector 11. The area S1 of the lithium host layer 22 or the negative electrode layer 20 is, for example, in the range of 50% to less than 100%, 50% to 99%, 55% to 98%, 60% to 97%, 70% to 96%, 80% to 95%, or 85% to 95% of the area S4 of the positive electrode current collector 11.

[0347] In this specification, "equal" areas, lengths, widths, thicknesses, and / or shapes may include all cases having "substantially equal" areas, lengths, widths, thicknesses, and / or shapes, excluding cases where the areas, lengths, widths, thicknesses, and / or shapes are intentionally different from each other. "Equal" areas, lengths, widths, and / or thicknesses include cases where the unintended differences in the areas, lengths, widths, and / or thicknesses between the objects being compared are, for example, less than 1%, less than 0.5%, or less than 0.1%.

[0348] The first inactive member 42 may be a gasket. By using a gasket as the first inactive member 42, cracks in the solid electrolyte layer 30 caused by a pressure difference during the pressing process can be effectively suppressed.

[0349] The first inactive member 42 has, for example, a single-layer structure. Optionally, although not shown in the drawings, the first inactive member 42 may have a multi-layer structure. In the first inactive member 42 having a multi-layer structure, each layer may have a different composition. The first inactive member 42 having a multi-layer structure may have, for example, a two-layer structure, a three-layer structure, a four-layer structure, or a five-layer structure. The first inactive member 42 having a multi-layer structure may include, for example, one or more adhesive layers and one or more support layers. For example, the adhesive layer effectively prevents the separation between the negative electrode layer 20 and the solid electrolyte layer 30 caused by the volume change of the negative electrode layer 20 during the charge / discharge process of the all-solid-state secondary battery 1, and provides the bonding force between the support layer and other layers to improve the film strength of the inactive member 40. The support layer provides a supporting force to the first inactive member 42, prevents the non-uniformity of the pressure applied to the solid electrolyte layer 30 during the pressing process or the charge / discharge process, and prevents the shape deformation of the all-solid-state secondary battery 1 to be manufactured.

[0350] Refer to Figure 14 and Figure 15, the all-solid-state secondary battery 1 includes a positive electrode layer 10, a negative electrode layer 20, and a solid electrolyte layer 30 disposed between the positive electrode layer 10 and the negative electrode layer 20. The positive electrode layer 10 includes a positive electrode current collector 11 and each of a first positive electrode active material layer 12a and a second positive electrode active material layer 12b disposed on both sides of the positive electrode current collector 11. The solid electrolyte layer 30 includes a first solid electrolyte layer 30a in contact with the first positive electrode active material layer 12a and a second solid electrolyte layer 30b in contact with the second positive electrode active material layer 12b. The negative electrode layer 20 includes a first negative electrode layer 20a in contact with the first solid electrolyte layer 30a and a second negative electrode layer 20b in contact with the second solid electrolyte layer 30b. A first non-active member 42 is disposed to surround the sides of the negative electrode layer 20 between the first solid electrolyte layer 30a and the first negative electrode current collector 21a facing each other and between the second solid electrolyte layer 30b and the second negative electrode current collector 21b facing each other. The first non-active member 42 includes, for example, a 1a non-active member 42a in contact with the first solid electrolyte layer 30a and a 1b non-active member 42b in contact with the second solid electrolyte layer 30b. Accordingly, the all-solid-state secondary battery 1 has a dual-cell structure. The all-solid-state secondary battery 1 has such a dual-cell structure, so that the solid electrolyte layer 30 and the negative electrode layer 20 are symmetrically disposed relative to the positive electrode layer 10 to face each other, thereby more effectively suppressing structural deformations and the like caused by the pressure applied during the manufacture of the all-solid-state secondary battery 1. Accordingly, cracks in the solid electrolyte layer 30 are suppressed during the manufacturing process and / or the charge / discharge process of the all-solid-state secondary battery 1, thus preventing a short circuit of the all-solid-state secondary battery 1, thereby further improving the cycle characteristics of the all-solid-state secondary battery 1. In addition, since only one positive electrode current collector 11 is used for the plurality of positive electrode active material layers 12a, 12b, the energy density of the all-solid-state secondary battery 1 is increased.

[0351] Refer to Figure 11 , Figure 13 and Figure 15, a part or all of the first inactive member 42 (42a or 42b) can be arranged to be spaced apart from the side surface of the lithium host layer 22 (22a or 22b). A part or all of the first inactive member 42 (42a or 42b) can be arranged to be spaced apart from the side surface of the lithium host layer 22 (22a or 22b), so that the manufacturing process of the all-solid-state secondary battery 1 can be made easier, and the manufacturing speed of the all-solid-state secondary battery 1 can be increased. Since a part or all of the first inactive member 42 (42a or 42b) is arranged to be spaced apart from the side surface of the lithium host layer 22 (22a or 22b), the volume change toward the side surface of the lithium host layer 22 (22a or 22b) can be more effectively accommodated during charge / discharge, thereby further improving the life characteristics of the all-solid-state secondary battery 1. The distances G2 (G2a and G2b) between the first inactive member 42 (42a and 42b) and the side surface of the lithium host layer 22 (22a and 22b) are each independently, for example, in the range of 0.1 μm to 10 mm, 1 μm to 1 mm, 1 μm to 500 μm, 1 μm to 100 μm, 1 μm to 50 μm, or 1 μm to 10 μm.

[0352] Optionally, although not shown in Figure 11 , Figure 13 and Figure 15 , the entire first inactive member 42 (42a or 42b) can be arranged to be spaced apart from the side surface of the lithium host layer 22 (22a or 22b), and the entire second inactive member 41 (41a or 41b) can be arranged to be in contact with the side surface of the positive electrode active material layer 12 (12a or 12b). Optionally, although not shown in Figure 11 , Figure 13 and Figure 15 , the entire first inactive member 42 (42a or 42b) can be arranged to be in contact with the side surface of the lithium host layer 22 (22a or 22b), and the entire second inactive member 41 (41a or 41b) can be arranged to be spaced apart from the side surface of the positive electrode active material layer 12 (12a or 12b).

[0353] Referring to Figures 10 to 15 , the first inactive member 42 is, for example, a flame-retardant inactive member. The flame-retardant inactive member can provide flame retardancy to prevent the possibility of thermal runaway and ignition of the all-solid-state secondary battery 1. Thus, the safety of the all-solid-state secondary battery 1 is further improved. The flame-retardant inactive member absorbs the residual moisture in the all-solid-state secondary battery 1, thereby preventing the deterioration of the all-solid-state secondary battery 1 and improving the life characteristics of the all-solid-state secondary battery 1.

[0354] The flame-retardant non-active member includes, for example, a matrix and a filler. The matrix includes, for example, a substrate and a reinforcing material. The matrix includes, for example, a fibrous substrate and a fibrous reinforcing material. The matrix may include a substrate to have elasticity. Thus, the matrix can effectively accommodate the volume change of the all-solid-state secondary battery 1 during charge / discharge and can be disposed at any one of various positions. The substrate included in the matrix includes, for example, a first fibrous material. Since the substrate includes the first fibrous material, the substrate can effectively accommodate the volume change of the negative electrode layer 20 that occurs during the charge / discharge process of the all-solid-state secondary battery 1 and can effectively suppress the deformation of the first non-active member 42 caused by the volume change of the negative electrode layer 20. The first fibrous material is, for example, a material having an aspect ratio of 5 or greater, 20 or greater, or 50 or greater. The first fibrous material is, for example, a material having an aspect ratio of 5 to 1000, 20 to 1000, or 50 to 1000. The first fibrous material is, for example, an insulating material. The first fibrous material may be an insulating material, so that a short circuit between the positive electrode layer 10 and the negative electrode layer 20 due to lithium dendrites or the like during the charge / discharge of the all-solid-state secondary battery 1 can be effectively prevented. The first fibrous material includes, for example, at least one selected from pulp fibers, insulating polymer fibers, and ion-conductive polymer fibers. The matrix includes a reinforcing material, so that the strength of the matrix is improved. Thus, the matrix can prevent the volume of the all-solid-state secondary battery 1 from changing excessively during charge / discharge and can prevent the deformation of the all-solid-state secondary battery 1. The reinforcing material included in the matrix includes, for example, a second fibrous material. The reinforcing material may include the second fibrous material, so that the strength of the matrix can be increased more uniformly. The second fibrous material is, for example, a material having an aspect ratio of 3 or greater, 5 or greater, or 10 or greater. The second fibrous material may be, for example, a material having an aspect ratio of 3 to 100, 5 to 100, or 10 to 100. The second fibrous material is, for example, a flame-retardant material. The second fibrous material may be a flame-retardant material, so that ignition caused by thermal runaway that occurs during the charge / discharge process of the all-solid-state secondary battery 1 or due to an external impact can be effectively suppressed. The second fibrous material is, for example, glass fiber, metal oxide fiber, or ceramic fiber.

[0355] In addition to the matrix, the flame-retardant non-active member further includes a filler. The filler may be provided in the matrix, on the surface of the matrix, or on both the inside and the surface. The filler includes, for example, inorganic materials. The filler included in the flame-retardant non-active member is, for example, a moisture absorbent or a lithium fixative. For example, the moisture absorbent can absorb moisture at a temperature of less than 100 °C to remove the moisture remaining in the all-solid-state secondary battery 1, thereby preventing the deterioration of the all-solid-state secondary battery 1. In addition, when the temperature of the all-solid-state secondary battery 1 rises to 150 °C or higher due to thermal runaway occurring during the charge / discharge process of the all-solid-state secondary battery 1 or due to an external impact, the moisture absorbent can release the absorbed moisture to effectively suppress the ignition of the all-solid-state secondary battery 1. That is to say, the moisture absorbent is, for example, a flame retardant. The moisture absorbent includes, for example, metal hydroxides having moisture absorption properties. The metal hydroxides included in the filler are, for example, Mg(OH)2, Fe(OH)3, Sb(OH)3, Sn(OH)4, Ti(OH)3, Zr(OH)4, Al(OH)3, or a combination thereof. The lithium fixative may be, for example, a compound that fixes lithium by reacting with liquid lithium at a temperature of 180 °C or higher, which is the melting temperature of lithium. The lithium fixative can react with, for example, liquid lithium to change lithium into other insoluble compounds. The lithium fixative is, for example, a metal oxide that reacts with liquid lithium. The metal oxides included in the filler are, for example, TiO2, ZrO2, HfO2, ThO2, or a combination thereof. The metal oxide reacts with, for example, liquid lithium to generate Li2O and a metal. The reaction formula is, for example, 4Li + MO2 → M + 2Li2O. The liquid lithium is fixed by reacting with the metal oxide to generate lithium oxide. The leakage of liquid lithium that melts at high temperatures into the positive electrode can be suppressed. Therefore, the safety of the all-solid-state secondary battery can be improved.

[0356] With respect to 100 parts by weight of the flame-retardant non-active member, the content of the filler included in the flame-retardant non-active member is, for example, in the range of 1 part by weight to 80 parts by weight, 5 parts by weight to 80 parts by weight, 10 parts by weight to 80 parts by weight, 20 parts by weight to 80 parts by weight, 30 parts by weight to 80 parts by weight, 40 parts by weight to 80 parts by weight, 50 parts by weight to 80 parts by weight, 60 parts by weight to 80 parts by weight, or 65 parts by weight to 80 parts by weight.

[0357] The flame-retardant non-active member may further include, for example, a binder. The binder may include, for example, a curable polymer or a non-curable polymer. The curable polymer is a polymer cured by heat and / or pressure. The curable polymer is, for example, solid at room temperature. The flame-retardant non-active member includes, for example, a thermally press-curable film and / or its cured product. The thermally press-curable polymer is, for example, TSA-66 of Toray.

[0358] In addition to the above-mentioned substrate, reinforcing material, filler, and binder, the flame-retardant inactive member may further include other materials. The flame-retardant inactive member may include, for example, at least one selected from paper, insulating polymers, ion-conductive polymers, insulating inorganic materials, oxide-based solid electrolytes, and sulfide-based solid electrolytes. The insulating polymer may be, for example, an olefin-based polymer such as polypropylene (PP) or polyethylene (PE).

[0359] The density of the substrate or reinforcing material included in the flame-retardant inactive member may be, for example, in the range of 10% to 300%, 10% to 150%, 10% to 140%, 10% to 130%, or 10% to 120% of the density of the negative electrode active material included in the lithium host layer 22.

[0360] The first inactive member 42 is a member that does not include an electrochemically active material (e.g., an electrode active material). The electrode active material is a material that adsorbs / desorbs lithium. The first inactive member 42 is a member composed of materials other than the electrode active material used in the art.

[0361] [Positive electrode layer]

[0362] [Positive electrode layer: Positive electrode active material]

[0363] Refer to Figures 10 to 17 , the positive electrode active material layer 12 includes a positive electrode active material.

[0364] The positive electrode active material may include, for example, a lithium-containing oxide-based positive electrode active material. The lithium-containing oxide-based positive electrode active material may include, for example, at least one composite oxide of lithium and a metal selected from cobalt, manganese, nickel, and combinations thereof. The lithium-containing oxide-based positive electrode active material may include, for example, a compound represented by at least one of the following formulas: Li a A 1-b B' b D2 (where 0.90 ≤ a ≤ 1 and 0 ≤ b ≤ 0.5); Li a E 1-b B' b O 2-c Dc (where 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, and 0 ≤ c ≤ 0.0); LiE 2-b B' b O 4-c D c (where 0 ≤ b ≤ 0.5 and 0 ≤ c ≤ 0.05); Li a Ni 1-b-c Co b B' c D α (where 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, and 0 < α ≤ 2); Li a Ni1-b-c Co b B' c O 2-α F' α (where 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05 and 0 < α < 2); Li a Ni 1-b-c Mn b B' c D α (where 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05 and 0 < α ≤ 2); Li a Ni 1-b-c Mn b B' c O 2-α F' α (where 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05 and 0 < α < 2); Li a Ni b E c G d O2 (where 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5 and 0.001 ≤ d ≤ 0.1); Li a Ni b Co c Mn d G e O2 (where 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0 ≤ d ≤ 0.5 and 0.001 ≤ e ≤ 0.1); Li a NiG b O2 (where 0.90 ≤ a ≤ 1 and 0.001 ≤ b ≤ 0.1); Li a CoG b O2 (where 0.90 ≤ a ≤ 1 and 0.001 ≤ b ≤ 0.1); Li a MnG b O2 (where 0.90 ≤ a ≤ 1 and 0.001 ≤ b ≤ 0.1); Li a Mn2G b O4 (where 0.90 ≤ a ≤ 1 and 0.001 ≤ b ≤ 0.1); LiV2O5; LiI'O2; LiNiVO4; Li (3-f) J2(PO4)3 (where 0 ≤ f ≤ 2); Li (3-f) Fe2(PO4)3 (where 0 ≤ f ≤ 2); and LiFePO4.

[0365] In the formula representing the above compound, A is Ni, Co, Mn, or a combination thereof; B' is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof; D is O, F, S, P, or a combination thereof; E is Co, Mn, or a combination thereof; F' is F, S, P, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; I' is Cr, V, Fe, Sc, Y, or a combination thereof; and J is V, Cr, Mn, Co, Ni, Cu, or a combination thereof.

[0366] The lithium-containing oxide-based positive electrode active material may include, for example, at least one selected from the group consisting of lithium transition metal oxides represented by Formula 1 to Formula 8.

[0367] Optionally, the positive electrode active material includes a lithium-containing sulfide-based positive electrode active material. The lithium-containing sulfide-based positive electrode active material is, for example, an electrode material in which lithium is added to a sulfur-based positive electrode active material. The sulfur-based positive electrode active material includes, for example, a sulfur-based material, a composite containing a sulfur-based material, or a combination thereof. The sulfur-based material may be, for example, inorganic sulfur, Li2S n (n>1), a disulfide compound, an organic sulfur compound, a carbon-sulfur polymer, or a combination thereof. The sulfur-containing composite may be a composite containing inorganic sulfur, Li2S n (n>1), a disulfide compound, an organic sulfur compound, a carbon-sulfur polymer, or a combination thereof. The composite of the sulfur-based material may include, for example: a composite of a sulfur-based material and carbon; a composite of a sulfur-based material, carbon, and a solid electrolyte; a composite of a sulfur-based material and a solid electrolyte; a composite of a sulfur-based material and a metal carbide; a composite of a sulfur-based material, carbon, and a metal carbide; a composite of a sulfur-based material and a metal nitride; a composite of a sulfur-based material, carbon, and a metal nitride; or a combination thereof. Since the lithium-containing sulfide-based positive electrode active material provides a higher discharge capacity per unit weight than the oxide-based positive electrode active material, the energy density per unit weight of the all-solid-state secondary battery including the lithium-containing sulfide-based positive electrode active material can be improved.

[0368] The lithium-containing sulfide-based positive electrode active material includes, for example, Li2S, a Li2S-containing composite, or a combination thereof. By including Li2S, a Li2S-containing composite, or a combination thereof having a high capacity as the lithium-containing sulfide-based positive electrode active material, the use of lithium metal can be omitted when manufacturing an all-solid-state secondary battery. Lithium metal may have high reactivity and high ductility, and thus may reduce the batch productivity during battery manufacturing. Therefore, the batch productivity of the all-solid-state secondary battery can be improved.

[0369] For example, a lithium-containing sulfide-based positive electrode active material (e.g., Li2S) undergoes de-lithiation during initial charging, causing a volume reduction, and then the volume increases again due to lithiation during subsequent discharging. Therefore, since the volume of the lithium-containing sulfide-based positive electrode active material changes while maintaining an ion and / or electron transport path through a conductive material or the like disposed around the lithium-containing sulfide-based positive electrode active material, the possibility of interruption of the ion and / or electron transport path is low. On the other hand, for example, a sulfur-based positive electrode active material (e.g., S) undergoes lithiation during initial discharging, causing a volume increase, and then the volume decreases again due to de-lithiation during subsequent charging. Therefore, since the initial ion and / or electron transport path of a conductive material or the like disposed around the sulfur-based positive electrode active material may collapse due to the initial volume increase of the sulfur-based positive electrode active material, the possibility of interruption of the ion and / or electron transport path is high.

[0370] The particle size of the lithium-containing sulfide-based positive electrode active material can be, for example, in the range of 1 nm to 50 μm, 10 nm to 50 μm, 50 nm to 40 μm, 100 nm to 30 μm, 500 nm to 30 μm, or 1 μm to 20 μm. Since the lithium-containing sulfide-based positive electrode active material has a particle size in such a range, the cycle characteristics of the all-solid-state secondary battery including the lithium-containing sulfide-based positive electrode active material can be further improved.

[0371] The particle size of Li2S can be, for example, in the range of 1 nm to 50 μm, 1 nm to 30 μm, or 1 nm to 10 μm. The particle size of the Li2S-containing composite can be, for example, in the range of 1 nm to 50 μm, 10 nm to 30 μm, 10 nm to 10 μm, or 10 nm to 1 μm.

[0372] The Li2S-containing composite is, for example, a composite of Li2S and a conductive material. The conductive material is, for example, an ion-conductive material, an electron-conductive material, or a combination thereof.

[0373] The electron conductivity of the electron-conductive material at a temperature of 25 °C is, for example, 1.0×10 3 S / m or greater, 1.0×10 4 S / m or greater, or 1.0×10 5S / m or greater. The electronically conductive material can be, for example, in the form of a particulate electronically conductive material, a plate-like electronically conductive material, a rod-like electronically conductive material, or a combination thereof, but is not limited thereto. The electronically conductive material can be, for example, carbon, metal powder, metal compound, etc. When carbon is included as the electronically conductive material, carbon has high electronic conductivity and is light, thereby achieving a high energy density per unit mass for the all-solid-state secondary battery. The electronically conductive material can have pores. Since the electronically conductive material has pores, Li2S can be included in the pores, thereby increasing the contact area between Li2S and the electronically conductive material and increasing the specific surface area of Li2S. The pore volume is, for example, in the range of 0.1 cc / g to 20.0 cc / g, 0.5 cc / g to 10 cc / g, or 0.5 cc / g to 5 cc / g. The average pore diameter is, for example, in the range of 1 nm to 100 nm, 1 nm to 50 nm, or 1 nm to 20 nm. When the average pore diameter is 15 nm or less, the BET specific surface area of the electronically conductive material having pores is in the range of 200 m 2 / g to 4500 m 2 / g, and when the average pore diameter exceeds 15 nm, the BET specific surface area of the electronically conductive material having pores is in the range of 100 m 2 / g to 2500 m 2 / g. The BET specific surface area, pore diameter, pore volume, and average pore diameter can be obtained, for example, by using the nitrogen absorption method.

[0374] The ionic conductivity of the ionically conductive material at a temperature of 25 °C is, for example, 1.0×10 -5 S / m or greater, 1.0×10 -4 S / m or greater, or 1.0×10 -3 S / m or greater. The ionically conductive material can have pores. Since the ionically conductive material has pores, Li2S can be included in the pores, thereby increasing the contact area between Li2S and the ionically conductive material and increasing the specific surface area of Li2S. The ionically conductive material can be, for example, in the form of a particulate ionically conductive material, a plate-like ionically conductive material, a rod-like ionically conductive material, or a combination thereof, but is not limited thereto. The ionically conductive material can be, for example, a sulfide-based solid electrolyte, an oxide-based solid electrolyte, etc. When a sulfide-based solid electrolyte is included as the ionically conductive material, the sulfide-based solid electrolyte can have high ionic conductivity and can be molded into various shapes, thereby achieving an all-solid-state secondary battery with a large capacity.

[0375] The Li2S-containing composite includes, for example: a composite of Li2S and carbon; a composite of Li2S, carbon, and a solid electrolyte; a composite of Li2S and a solid electrolyte; a composite of Li2S and a metal carbide; a composite of Li2S, carbon, and a metal carbide; a composite of Li2S and a metal nitride; a composite of Li2S, carbon, and a metal nitride; a composite of Li2S and a metal; a composite of Li2S, a metal, and carbon; or a combination thereof.

[0376] The composite of Li2S and carbon includes carbon. As the carbon, for example, any material can be used as long as the material is a material including carbon atoms and is used as a conductive material in the art. The carbon can be, for example, crystalline carbon, amorphous carbon, or a combination thereof. The carbon can be, for example, a sintered product of a carbon precursor. The carbon can include, for example, a carbon nanostructure. The carbon nanostructure can include, for example, a one-dimensional carbon nanostructure, a two-dimensional carbon nanostructure, a 3D carbon nanostructure, or a combination thereof. The carbon nanostructure can include, for example, CNT, CNF, carbon nanobelt, carbon nanorod, graphene, GO, rGO, GB, or a combination thereof. The carbon can be, for example, porous carbon or non-porous carbon. The porous carbon can include, for example, periodic and regular two-dimensional or 3D pores. The porous carbon can include, for example, CB, such as KB, AB, Denka black, thermal black, or channel black; graphite; activated carbon; or a combination thereof. The form of the carbon is, for example, a particulate form, a sheet form, a flake form, etc., but one or more embodiments are not limited thereto. Any material can be used as long as the material is used as carbon in the art. The method for preparing the composite of Li2S and carbon can be a dry method, a wet method, or a combination thereof, but is not limited thereto. In the art, the method for preparing the composite of Li2S and carbon can include, for example, grinding, heat treatment, deposition, etc., but one or more embodiments are not limited thereto. Any method can be used as long as the method is used in the art.

[0377] The composite of Li2S, carbon, and a solid electrolyte includes carbon and a solid electrolyte. The carbon is as defined in the above composite of Li2S and carbon. As the solid electrolyte, for example, any material can be used as long as the material is used as an ion-conductive material in the art. The solid electrolyte is, for example, an inorganic solid electrolyte. The solid electrolyte is, for example, a crystalline solid electrolyte, an amorphous solid electrolyte, or a combination thereof. The solid electrolyte is, for example, a sulfide-based solid electrolyte, an oxide-based solid electrolyte, a lithium salt compound, or a combination thereof. The sulfide-based solid electrolyte can include, for example, Li, S, and P and can optionally further include a halogen element. The sulfide-based solid electrolyte can be selected from the sulfide-based solid electrolytes used in a solid electrolyte layer. For example, the sulfide-based solid electrolyte can have 1×10 at room temperature -5An ionic conductivity of S / cm or greater. Sulfide-based solid electrolytes can include, for example, those selected from Li3PO4-Li2SO4, Li2S-P2S5, Li2S-P2S5-LiX (where X is a halogen element), Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-Z m S n (where m and n are each positive numbers, and Z is one of Ge, Zn, and Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (where p and q are each positive numbers, and M is one of P, Si, Ge, B, Al, Ga, and In), Li 7-x PS 6-x Cl x (where 0 ≤ x ≤ 2), Li 7-x PS 6-x Br x (where 0 ≤ x ≤ 2), and Li 7-x PS 6-x I x (where 0 ≤ x ≤ 2) and at least one of the above. Oxide-based solid electrolytes can include, for example, Li, O, and transition metal elements, and may optionally further include other elements. For example, oxide-based solid electrolytes can have 1×10 -5A solid electrolyte having an ionic conductivity of S / cm or greater. The oxide-based solid electrolyte can be selected from the oxide-based solid electrolytes used in the solid electrolyte layer. The lithium salt compound is, for example, an inorganic compound. The solid electrolyte includes, for example, a lithium salt compound, and the lithium salt compound does not include, for example, a sulfur (S) atom. The lithium salt compound can be, for example, a binary compound including lithium and one element selected from Groups 13 to 17 of the periodic table. The binary compound can include, for example, at least one selected from LiF, LiCl, LiBr, LiI, LiH, Li2S, Li2O, Li2Se, Li2Te, Li3N, Li3P, Li3As, Li3Sb, LiI3, and LiB3. The lithium salt compound can be, for example, a ternary compound including lithium and two elements selected from Groups 13 to 17 of the periodic table. The ternary compound includes, for example, at least one selected from Li3OCl, LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiAlO2, LiAlCl4, LiNO3, Li2CO3, LiBH4, Li2SO4, Li3BO3, Li3PO4, Li4NCl, Li5NCl2, and Li3BN2. The lithium salt compound includes at least one lithium halide compound selected from LiF, LiCl, LiBr, and LiI. The solid electrolyte can be, for example, a mixture of a sulfide-based solid electrolyte and a lithium salt compound. For example, the solid electrolyte is a mixture of Li3PO4-Li2SO4 and a binary lithium salt compound or a mixture of Li3PO4-Li2SO4 and a ternary lithium salt compound.

[0378] The composite of Li2S and the solid electrolyte includes the solid electrolyte. The solid electrolyte is as defined above for the solid electrolyte used in the composite of Li2S, carbon, and the solid electrolyte. The composite of Li2S and the solid electrolyte includes, for example, the composite of Li2S and at least one lithium salt selected from LiF, LiCl, LiBr, LiI, LiH, Li2S, Li2O, Li2Se, Li2Te, Li3N, Li3P, Li3As, Li3Sb, LiI3, and LiB3.

[0379] The composite of Li2S and the metal carbide includes the metal carbide. The metal carbide is, for example, a two-dimensional metal carbide. The two-dimensional metal carbide is, for example, MXene. The two-dimensional metal carbide is, for example, represented by M n+1 C n T x where M is a transition metal, T is a terminal group, T is O, OH, and / or F, n = 1, 2, or 3, and x is the number of terminal groups. The two-dimensional metal carbide is, for example, Ti2CT x , (Ti 0.5 , Nb 0.5 )2CT x, Nb2CT x , V2CT x , Ti3C2T x , (V 0.5 , Cr 0.5 )3C2T x , Ti3CNT x , Ta4C3T x , Nb4C3T x or a combination thereof. The surface of the two-dimensional metal carbide is capped with O, OH, and / or F.

[0380] The composite of Li2S, carbon, and metal carbide includes carbon and metal carbide. The carbon is as defined in the composite of Li2S and carbon described above. The metal carbide is as defined in the composite of Li2S and metal carbide described above.

[0381] The composite of Li2S and metal nitride includes metal nitride. The metal nitride is, for example, a two-dimensional metal nitride. The two-dimensional metal nitride is, for example, represented by M n+1 N n T x , where M is a transition metal, T is a capping group, T is O, OH, and / or F, n = 1, 2, or 3, and x is the number of capping groups. The surface of the two-dimensional metal nitride is capped with O, OH, and / or F.

[0382] The composite of Li2S, carbon, and metal nitride includes carbon and metal nitride. The carbon is as defined in the composite of Li2S and carbon described above. The metal nitride is as defined in the composite of Li2S and metal nitride described above.

[0383] The composite of Li2S and metal includes metal nanostructures. The metal nanostructures include one-dimensional metal nanostructures, two-dimensional metal nanostructures, 3D metal nanostructures, or a combination thereof. The metal nanostructures include metal nanoparticles, metal nanofibers, or a combination thereof. The metal nanostructures include, for example, copper (Cu), aluminum (Al), nickel (Ni), or a combination thereof.

[0384] The composite of Li2S, metal, and carbon includes metal and carbon. The metal is as defined in the composite of Li2S and metal described above. The carbon is as defined in the composite of Li2S and carbon described above.

[0385] The positive electrode active material layer 12 may include a lithium-containing sulfide-based positive electrode active material, and the content of the lithium-containing sulfide-based positive electrode active material may be, for example, in the range of 10 wt% to 90 wt%, 10 wt% to 80 wt%, 10 wt% to 70 wt%, 10 wt% to 60 wt%, or 10 wt% to 50 wt% of the total weight of the positive electrode active material layer 12.

[0386] For example, the positive electrode active material layer 12 may further include a sulfide compound different from Li2S. The sulfide compound different from Li2S may be, for example, a compound including a sulfur element and a metal element other than Li. For example, the sulfide compound may be a compound including a sulfur element and at least one metal element having an atomic weight of 10 or more and belonging to Groups 1 to 14 of the periodic table. The sulfide compound may be, for example, FeS2, VS2, NaS, MnS, FeS, NiS, CuS, or a combination thereof. The positive electrode active material layer may further include a sulfide compound, so that the cycle characteristics of the all-solid-state secondary battery can be further improved. The content of the sulfide compound included in the positive electrode active material layer 12 and different from Li2S may be 10 wt% or less, 5 wt% or less, 3 wt% or less, or 1 wt% or less of the total weight of the positive electrode active material layer 12.

[0387] The thickness of the positive electrode active material layer 12 may be, for example, in the range of 1 μm to 100 μm or 10 μm to 60 μm.

[0388] [Positive electrode layer: Solid electrolyte]

[0389] The positive electrode active material layer 12 may further include, for example, a solid electrolyte. The solid electrolyte may be, for example, a sulfide-based solid electrolyte. The solid electrolyte included in the positive electrode layer 10 may be selected from the solid electrolytes included in the solid electrolyte layer 30. The solid electrolyte is as defined in a part of the solid electrolyte layer 30.

[0390] The solid electrolyte included in the positive electrode active material layer 12 may have a D50 average particle size smaller than that of the solid electrolyte included in the solid electrolyte layer 30. For example, the D50 average particle size of the solid electrolyte included in the positive electrode active material layer 12 may be 90% or less, 80% or less, 70% or less, 60% or less, 50% or less, 40% or less, 30% or less, or 20% or less of the D50 average particle size of the solid electrolyte included in the solid electrolyte layer 30. The D50 average particle size is, for example, the median particle size (D50). The median particle size (D50) is the particle size corresponding to 50% cumulative volume when calculating the particle size distribution measured by the laser diffraction method from the particles having a smaller particle size.

[0391] The particle size of the sulfide-based solid electrolyte included in the positive electrode active material layer 12 may be, for example, in the range of 1 nm to 50 μm, 10 nm to 30 μm, 50 nm to 10 μm, or 100 nm to 3 μm.

[0392] The content of the solid electrolyte included in the positive electrode active material layer 12 may be, for example, in the range of 1 wt% to 40 wt%, 1 wt% to 30 wt%, 1 wt% to 20 wt%, or 1 wt% to 10 wt% of the total weight of the positive electrode active material layer 12.

[0393] [Positive electrode layer: Conductive material]

[0394] The positive electrode active material layer 12 may further include a conductive material. The conductive material may be, for example, a carbon-based conductive material, a metal-based conductive material, or a combination thereof. The carbon-based conductive material may be, for example, graphite, CB, AB, KB, carbon fiber, or a combination thereof, but one or more embodiments are not limited thereto. Any material may be used as long as the material is used as a carbon-based conductive material in the art. The metal-based conductive material may be metal powder, metal fiber, or a combination thereof, but one or more embodiments are not limited thereto. Any material may be used as long as the material is used as a metal-based conductive material in the art. The content of the conductive material included in the positive electrode active material layer 12 may be, for example, in the range of 1 wt% to 30 wt%, 1 wt% to 20 wt%, or 1 wt% to 10 wt% of the total weight of the positive electrode active material layer 12.

[0395] [Positive electrode layer: Binder]

[0396] The positive electrode active material layer 12 may further include a binder. The binder includes, for example, SBR, PTFE, PVDF, PE, etc., but one or more embodiments are not limited thereto. Any material may be used as long as the material is used as a binder in the art. The content of the binder included in the positive electrode active material layer 12 may be, for example, in the range of 1 wt% to 10 wt% of the total weight of the positive electrode active material layer 12. The binder may be omitted.

[0397] [Positive electrode layer: Other additives]

[0398] In addition to the above positive electrode active material, solid electrolyte, binder, and conductive material, the positive electrode active material layer 12 may further include, for example, additives such as fillers, coating agents, dispersants, and ion conductive aids.

[0399] As the fillers, coating agents, dispersants, ion conductive aids, etc. that may be included in the positive electrode active material layer 12, known materials commonly used in the electrodes of all-solid-state secondary batteries may be used.

[0400] [Positive electrode layer: Positive electrode current collector]

[0401] The positive electrode current collector 11 can be provided as a plate, foil, etc. composed of, for example, indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), or an alloy thereof. The positive electrode current collector 11 can be omitted. The thickness of the positive electrode current collector 11 is, for example, in the range of 1 μm to 100 μm, 1 μm to 50 μm, 5 μm to 25 μm, or 10 μm to 20 μm.

[0402] The positive electrode current collector 11 can also include a substrate containing the above metals and an intermediate layer provided on the substrate. The intermediate layer can be, for example, a conductive coating. For example, the intermediate layer can include a carbon-based conductive material or a mixture of a carbon-based conductive material and a binder. Since the positive electrode current collector 11 additionally includes an intermediate layer, the interfacial resistance between the positive electrode active material layer and the positive electrode current collector can be reduced, thereby reducing the internal resistance of the all-solid-state secondary battery 1.

[0403] The positive electrode current collector 11 can include, for example, a base film and metal layers provided on one or both sides of the base film. The base film can include, for example, a polymer. The polymer can include, for example, PET, PE, PP, PBT, PI, or a combination thereof. The metal layer can include, for example, indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), or an alloy thereof. Since the positive electrode current collector 11 has such a structure, the weight of the electrode can be reduced, thereby improving the energy density of the all-solid-state secondary battery.

[0404] [Positive Electrode Layer: Second Inactive Member]

[0405] Refer to Figures 10 to 15 , the positive electrode layer 10 includes a positive electrode current collector 11 and a positive electrode active material layer 12 provided on one side of the positive electrode current collector 11. The second inactive member 41 is provided on the side surface of the positive electrode layer 10.

[0406] The second inactive member 41 provided on the side surface of the positive electrode layer 10 can be selected from the first inactive members 42 provided on the side surface of the negative electrode layer 20 described above.

[0407] Refer to Figure 10 and Figure 11 , the second inactive member 41 is provided on the side surface of the positive electrode active material layer 12, and is provided between the solid electrolyte layer 30 and the positive electrode current collector 11 opposite to the solid electrolyte layer 30. The second inactive member 41 is not provided on the side surface of the positive electrode current collector 11. Refer to Figure 12 , Figure 13 , Figure 14 and Figure 15, the second inactive member 41 is disposed on the side surfaces of the positive electrode active material layer 12 and the positive electrode current collector 11. The second inactive member 41 is included to prevent cracks in the solid electrolyte layer 30 during the manufacturing and / or charging / discharging of the all-solid-state secondary battery 1, thereby improving the cycle characteristics of the all-solid-state secondary battery 1. In the all-solid-state secondary battery 1 that does not include the second inactive member 41, uneven pressure is applied to the solid electrolyte layer 30 in contact with the positive electrode layer 10 during the manufacturing and / or charging / discharging of the all-solid-state secondary battery 1, thereby causing cracks in the solid electrolyte layer 30, and lithium metal grows through the cracks, thereby increasing the possibility of short circuit occurrence.

[0408] Refer to Figures 10 to 15 , in the all-solid-state secondary battery 1, for the description of the thickness of the second inactive member 41, refer to the description of the thickness of the first inactive member 42 above.

[0409] Refer to Figures 10 to 15 , the second inactive member 41 surrounds the side surfaces of the positive electrode layer 10 and is in contact with the solid electrolyte layer 30. The second inactive member 41 can surround the side surfaces of the positive electrode layer 10 and can be in contact with the solid electrolyte layer 30, thereby effectively suppressing cracks in the solid electrolyte layer 30 that are caused by the pressure difference during the pressing process in the portion of the solid electrolyte layer 30 that is not in contact with the positive electrode layer 10. The second inactive member 41 surrounds the side surfaces of the positive electrode layer 10 and is separated from the negative electrode layer 20 (more specifically, the lithium host layer 22). The second inactive member 41 surrounds the side surfaces of the positive electrode layer 10, is in contact with the solid electrolyte layer 30, and is separated from the negative electrode layer 20. Therefore, the possibility of short circuit occurrence due to physical contact between the positive electrode layer 10 and the lithium host layer 22 or due to overcharging of lithium is suppressed. The second inactive member 41 is disposed on both the side surfaces of the positive electrode active material layer 12 and the positive electrode current collector 11, thereby more effectively suppressing the possibility of short circuit caused by contact between the positive electrode current collector 11 and the negative electrode layer 20.

[0410] Refer to Figures 10 to 17, the second inactive member 41 (41a or 41b) extends from the side of the positive electrode layer 10 to the end of the solid electrolyte layer 30. The second inactive member 41 extends to the end of the solid electrolyte layer 30, thereby suppressing the generation of cracks at the end of the solid electrolyte layer 30. The end of the solid electrolyte layer 30 is the outermost portion in contact with the side of the solid electrolyte layer 30. The second inactive member 41 extends to the outermost portion in contact with the side of the solid electrolyte layer 30. The second inactive member 41 is separated from the negative electrode layer 20 (more specifically, the lithium host layer 22). The second inactive member 41 extends to the end of the solid electrolyte layer 30 but does not contact the negative electrode layer 20. For example, the second inactive member 41 fills the space extending from the side of the positive electrode layer 10 to the end of the solid electrolyte layer 30.

[0411] For the description of the width of the second inactive member 41 extending from the side of the positive electrode layer 10 to the end of the solid electrolyte layer 30 and the width between one side of the positive electrode active material layer 12 and the other side opposite thereto, refer to the description of the width of the first inactive member 42 above. For the description of the area of the positive electrode active material layer 12 or the positive electrode layer 10, the area of the solid electrolyte layer 30 in contact with the positive electrode layer 10, the area of the second inactive member 41, and the area of the positive electrode current collector 11, refer to the description of the areas of these elements above.

[0412] The second inactive member 41 can be a gasket. By using a gasket as the second inactive member 41, cracks in the solid electrolyte layer 30 caused by a pressure difference during the pressing process can be effectively suppressed.

[0413] The second inactive member 41 has, for example, a single-layer structure. Optionally, although not shown in the drawings, the second inactive member 41 can have a multi-layer structure. In the second inactive member 41 having a multi-layer structure, each layer can have a different composition. The second inactive member 41 having a multi-layer structure can have, for example, a two-layer structure, a three-layer structure, a four-layer structure, or a five-layer structure. The first inactive member 42 having a multi-layer structure can include, for example, one or more adhesive layers and one or more support layers. For example, the adhesive layer can effectively prevent the separation between the positive electrode layer 10 and the solid electrolyte layer 30 due to the volume change of the positive electrode layer 10 during the charge / discharge process of the all-solid-state secondary battery 1, and can provide the bonding force between the support layer and other layers to improve the film strength of the inactive member 40. The support layer provides a supporting force to the second inactive member 41, prevents the non-uniformity of the pressure applied to the solid electrolyte layer 30 during the pressing process or the charge / discharge process, and prevents the shape deformation of the all-solid-state secondary battery 1 to be manufactured.

[0414] Refer to Figure 14 and Figure 15, the all-solid-state secondary battery 1 includes a positive electrode layer 10, a negative electrode layer 20, a solid electrolyte layer 30 disposed between the positive electrode layer 10 and the negative electrode layer 20, and a second non-active member 41. Among them, the positive electrode layer 10 includes a positive electrode current collector 11 and each of a first positive electrode active material layer 12a and a second positive electrode active material layer 12b disposed on both sides of the positive electrode current collector 11. The solid electrolyte layer 30 includes each of a first solid electrolyte layer 30a in contact with the first positive electrode active material layer 12a and a second solid electrolyte layer 30b in contact with the second positive electrode active material layer 12b. The negative electrode layer 20 includes each of a first negative electrode layer 20a in contact with the first solid electrolyte layer 30a and a second negative electrode layer 20b in contact with the second solid electrolyte layer 30b. The second non-active member 41 is disposed to surround the side surface of the positive electrode layer 10 between the first solid electrolyte layer 30a and the second solid electrolyte layer 30b facing each other. The second non-active member 41 includes, for example, a 2a non-active member 41a in contact with the first solid electrolyte layer 30a and a 2b non-active member 41b in contact with the second solid electrolyte layer 30b. Therefore, the all-solid-state secondary battery 1 has a dual-cell structure. The all-solid-state secondary battery 1 has such a dual-cell structure, so the solid electrolyte layer 30 and the negative electrode layer 20 are symmetrically disposed relative to the positive electrode layer 10 to face each other, thereby more effectively suppressing structural deformation and the like caused by the pressure applied during the manufacture of the all-solid-state secondary battery 1. Therefore, cracks in the solid electrolyte layer 30 are suppressed during the manufacturing process and / or the charge / discharge process of the all-solid-state secondary battery 1, thus preventing short circuits in the all-solid-state secondary battery 1, and further improving the cycle characteristics of the all-solid-state secondary battery 1. In addition, only one positive electrode current collector 11 is used for the plurality of positive electrode active material layers 12a, 12b, so the energy density of the all-solid-state secondary battery 1 is improved.

[0415] Refer to Figure 11 , Figure 13 and Figure 15, the whole or a part of the second inactive member 41 (41a or 41b) may be arranged to be spaced apart from the side surface of the positive electrode active material layer 12 (12a or 12b). The whole or a part of the second inactive member 41 (41a or 41b) may be arranged to be spaced apart from the side surface of the positive electrode active material layer 12 (12a or 12b), so that the manufacturing process of the all-solid-state secondary battery 1 can be made easier, and the manufacturing speed of the all-solid-state secondary battery 1 can be increased. Since the whole or a part of the second inactive member 41 (41a or 41b) is arranged to be spaced apart from the side surface of the positive electrode active material layer 12 (12a or 12b), the volume change toward the side surface of the positive electrode active material layer 12 (12a or 12b) can be more effectively accommodated during charge / discharge, thereby further improving the life characteristics of the all-solid-state secondary battery 1. The distances G1 (G1a and G1b) between the second inactive member 41 (41a and 41b) and the side surface of the positive electrode active material layer 12 (12a and 12b) are each independently in the range of, for example, 0.1 μm to 10 mm, 1 μm to 1 mm, 1 μm to 500 μm, 1 μm to 100 μm, 1 μm to 50 μm, or 1 μm to 10 μm.

[0416] Reference Figures 10 to 15 , the second inactive member 41 is, for example, a flame-retardant inactive member. The flame-retardant inactive member used as the second inactive member 41 may be selected from the above-mentioned flame-retardant inactive members used in the first inactive member 42.

[0417] [Solid electrolyte layer]

[0418] [Solid electrolyte layer: Solid electrolyte]

[0419] Reference Figures 10 to 15 , the solid electrolyte layer 30 includes an electrolyte disposed between the positive electrode layer 10 and the negative electrode layer 20. The electrolyte may include, for example, a solid electrolyte, a gel electrolyte, or a combination thereof.

[0420] The solid electrolyte may include, for example, a sulfide-based solid electrolyte, an oxide-based solid electrolyte, a polymer solid electrolyte, or a combination thereof.

[0421] The solid electrolyte may be, for example, a sulfide-based solid electrolyte. The sulfide-based solid electrolyte may include, for example, those selected from Li2S-P2S5, Li2S-P2S5-LiX (where X is a halogen element), Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-Z m S n (where m and n are each positive numbers, and Z is one of Ge, Zn, and Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (where p and q are each positive numbers, and M is one of P, Si, Ge, B, Al, Ga, and In), Li 7-x PS 6-x Cl x (where 0 ≤ x ≤ 2), Li 7-x PS 6-x Br x (where 0 ≤ x ≤ 2), and Li 7-x PS 6-x I x (where 0 ≤ x ≤ 2), and at least one of them. For example, the sulfide-based solid electrolyte is prepared by treating starting materials such as Li2S or P2S5 via melt quenching or mechanical grinding. In addition, after such treatment, heat treatment may be performed. The solid electrolyte may be in an amorphous state, a crystalline state, or a mixed state of amorphous and crystalline states. In addition, the solid electrolyte may be, for example, a material that includes at least sulfur (S), phosphorus (P), and lithium (Li) as constituent elements among the above materials of the sulfide-based solid electrolyte. For example, the solid electrolyte may be a material including Li2S-P2S5. When a material including Li2S-P2S5 is used as the sulfide-based solid electrolyte material for forming the solid electrolyte, the mixing molar ratio of Li2S to P2S5 (e.g., Li2S:P2S5) is in the range of 20:80 to 90:10, 25:75 to 90:10, 30:70 to 70:30, or 40:60 to 60:40.

[0422] The sulfide-based solid electrolyte may include, for example, a thiargite-type solid electrolyte represented by the following formula 9:

[0423] Formula 9

[0424] Li +12-n-x A n+ X 2- 6-x Y - x 。

[0425] In the above formula, A is P, As, Ge, Ga, Sb, Si, Sn, Al, In, Ti, V, Nb or Ta, X is S, Se or Te, Y is Cl, Br, I, F, CN, OCN, SCN or N3, 1 ≤ n ≤ 5, and 0 ≤ x ≤ 2. The sulfide-based solid electrolyte may be, for example, a thiogermanate compound including at least one selected from Li 7-x PS 6-x Cl x (where 0 ≤ x ≤ 2), Li 7-x PS 6-x Br x (where 0 ≤ x ≤ 2) and Li 7-x PS 6-x I x (where 0 ≤ x ≤ 2). The sulfide-based solid electrolyte may be, for example, a thiogermanate compound including at least one selected from Li6PS5Cl, Li6PS5Br and Li6PS5I.

[0426] The thiogermanate solid electrolyte may have a density of 1.5 g / cc to 2.0 g / cc. Since the thiogermanate solid electrolyte has a density of 1.5 g / cc or more, the internal resistance of the all-solid-state secondary battery can be reduced, and Li penetration through the solid electrolyte layer can be effectively suppressed.

[0427] The oxide-based solid electrolyte may include, for example, Li 1+x+y Al x Ti 2-x Si y P 3-y O 12 (where 0 < x < 2 and 0 ≤ y < 3), BaTiO3, Pb(Zr,Ti)O3 (PZT), Pb 1-x La x Zr 1-y Ti y O3 (PLZT) (where 0 ≤ x < 1 and 0 ≤ y < 1), Pb(Mg3Nb 2 / 3 )O3 - PbTiO3 (PMN - PT), HfO2, SrTiO3, SnO2, CeO2, Na2O, MgO, NiO, CaO, BaO, ZnO, ZrO2, Y2O3, Al2O3, TiO2, SiO2, Li3PO4, Li x Ti y(PO4)3 (where 0 < x < 2 and 0 < y < 3), Li x Al y Ti z (PO4)3 (where 0 < x < 2, 0 < y < 1 and 0 < z < 3), Li 1+x+y (Al, Ga) x (Ti, Ge) 2-x Si y P 3-y O 12 (where 0 ≤ x ≤ 1 and 0 ≤ y ≤ 1), Li x La y TiO3 (where 0 < x < 2 and 0 < y < 3), Li2O, LiOH, Li2CO3, LiAlO2, Li2O - Al2O3 - SiO2 - P2O5 - TiO2 - GeO2, Li 3+x La3M2O 12 (where M = Te, Nb or Zr and 0 ≤ x ≤ 10) or a combination thereof. Oxide - based solid electrolytes are prepared, for example, by sintering or the like.

[0428] Oxide - based solid electrolytes are, for example, selected from Li7La3Zr2O 12 (LLZO) and Li 3+x La3Zr 2-a M a O 12 (LLZO doped with M) (where M = Ga, W, Nb, Ta or Al, 0 < a < 2 and 0 ≤ x ≤ 10), a garnet - type solid electrode.

[0429] For example, polymer solid electrolytes can include a mixture of a lithium salt and a polymer or can include a polymer having an ion - conductive functional group. Polymer solid electrolytes can be, for example, polymer electrolytes in a solid state at a temperature of 25 °C and a pressure of 1 atm. Polymer solid electrolytes can not include, for example, liquids. Polymer solid electrolytes can include polymers, and the polymers can include, for example, PEO, PVDF, PVDF - HFP, PEO, PS - PEO block copolymer, poly(styrene - butadiene), poly(styrene - isoprene - styrene), poly(styrene - b - divinylbenzene) block copolymer, poly(styrene - ethylene oxide - styrene) block copolymer, PSS, PVF, PMMA, PEG, PAN, PTFE, PEDOT, PPY, PAN, polyaniline, polyacetylene, - ADP, SPEEK, SPAEKKS, SPAEK, SPBIBI, PSS, DPASLi +or combinations thereof, but one or more embodiments are not limited thereto. Any material can be used as long as it is used in the field of polymer electrolytes. As the lithium salt, any material can be used as long as it can be used as a lithium salt in the field. Lithium salts include, for example, LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiCF3SO3, Li(CF3SO2)2N, LiC4F9SO3, LiAlO2, LiAlCl4, LiN(C x F 2x+1 SO2)(C y F 2y+1 SO2)(where x and y are each natural numbers from 1 to 20), LiCl, LiI, or mixtures thereof. The polymer included in the polymer solid electrolyte can be, for example, a compound including 10 or more, 20 or more, 50 or more, or 100 or more repeating units. The weight-average molecular weight of the polymer included in the polymer solid electrolyte can be, for example, 1000 daltons or greater, 10000 daltons or greater, 100000 daltons or greater, or 1000000 daltons or greater.

[0430] The gel electrolyte can include, for example, a polymer gel electrolyte. The gel electrolyte can have a gel state and does not include, for example, a liquid.

[0431] The polymer gel electrolyte can include, for example, a liquid electrolyte and a polymer, or can include an organic solvent and a polymer having an ion-conductive functional group. The polymer gel electrolyte can be, for example, a polymer electrolyte in a gel state at a temperature of 25 °C and a pressure of 1 atm. The polymer gel electrolyte can have, for example, a gel state and does not include a liquid. The liquid electrolyte used in the polymer gel electrolyte can include, for example: a mixture of an ionic liquid and a lithium salt; a mixture of a lithium salt and an organic solvent; a mixture of an ionic liquid and an organic solvent; or a mixture of a lithium salt, an ionic liquid, and an organic solvent. The polymer used in the polymer gel electrolyte can be selected from the polymers used in the solid polymer electrolyte. The organic solvent can be selected from the organic solvents used in the liquid electrolyte. The lithium salt can be selected from the lithium salts used in the polymer solid electrolyte. An ionic liquid refers to a salt in a liquid state at room temperature or a room-temperature molten salt having a melting point at room temperature or lower and consisting only of ions. The ionic liquid can include, for example, at least one compound, the compound including a) one cation selected from ammonium cations, pyrrolidinium cations, pyridinium cations, pyrimidinium cations, imidazolium cations, piperidinium cations, pyrazolium cations, oxazolium cations, pyridazinium cations, phosphonium cations, sulfonium cations, triazolium cations, and mixtures thereof, and b) selected from BF4 - 、PF6- , AsF6 - , SbF6 - , AlCl4 - , HSO4 - , ClO4 - , CH3SO3 - , CF3CO2 - , Cl - , Br - , I - , BF4 - , SO4 - , CF3SO3 - , (FSO2)2N - , (C2F5SO2)2N - , (C2F5SO2)(CF3SO2)N - and (CF3SO2)2N - and at least one anion selected from the group consisting of. The polymer solid electrolyte can be impregnated in a liquid electrolyte in, for example, a secondary battery to form a polymer gel electrolyte. The polymer gel electrolyte may also include inorganic particles. The polymer included in the polymer gel electrolyte may be a compound including, for example, 10 or more, 20 or more, 50 or more, or 100 or more repeating units. The weight average molecular weight of the polymer included in the polymer gel electrolyte may be, for example, 500 daltons or greater, 1000 daltons or greater, 10000 daltons or greater, 100000 daltons or greater, or 1000000 daltons or greater.

[0432] The solid electrolyte layer 30 may be impermeable to lithium polysulfide. Therefore, side reactions between the negative electrode layer and lithium polysulfide generated during charging or discharging of the sulfide-based positive electrode active material can be prevented. Therefore, the cycle characteristics of the all-solid-state secondary battery 1 including the solid electrolyte layer 30 can be improved.

[0433] [Solid electrolyte layer: Binder]

[0434] The solid electrolyte layer 30 may include, for example, a binder. The binder included in the solid electrolyte layer 30 may include, for example, SBR, PTFE, PVDF, PE, etc., but one or more embodiments are not limited thereto. Any material can be used as long as the material is used as a binder in the art. The binder of the solid electrolyte layer 30 may be the same as or different from the binder included in the positive electrode active material layer 12 and the negative electrode active material layer 22. The binder may be omitted.

[0435] The content of the binder included in the solid electrolyte layer 30 is in the range of 0.1 wt% to 10 wt%, 0.1 wt% to 5 wt%, 0.1 wt% to 3 wt%, 0.1 wt% to 1 wt%, 0 wt% to 0.5 wt%, or 0 wt% to 0.1 wt% relative to the total weight of the solid electrolyte layer 30.

[0436] Specific embodiments of the invention

[0437] The inventive concept will be described in more detail through the following examples and comparative examples. However, the examples are for illustrative purposes only, and the scope of the inventive concept is not limited by the examples.

[0438] Example 1: Single-cell all-solid-state secondary battery, sulfide-based positive electrode active material (Li2S-C-solid electrolyte composite), first negative electrode active material layer, first flame-retardant non-active member, and second flame-retardant non-active member

[0439] (Preparation of negative electrode layer)

[0440] A SUS foil with a thickness of 10 μm was prepared as the negative electrode current collector. In addition, as the negative electrode active material, CB with a primary particle size of about 30 nm and silver (Ag) particles with an average particle size of about 60 nm were prepared.

[0441] 4 g of the mixed powder obtained by mixing CB and silver (Ag) particles at a weight ratio of 3:1 was placed in a container, and 4 g of an N-methyl-2-pyrrolidone (NMP) solution containing 7 wt% of a PVDF binder (#9300 manufactured by Kureha Corporation) was added thereto to prepare a mixed solution. Next, while gradually adding NMP to the prepared mixed solution, the mixed solution was stirred to prepare a slurry. The prepared slurry was applied to the SUS sheet using a bar coater and dried in air at a temperature of 80 °C for 10 minutes. Thus, the obtained stack was vacuum dried at a temperature of 40 °C for 10 hours. The dried stack was cold roll-pressed at a pressure of 5 tf / cm 2 at a speed of 5 m / s to flatten the surface of the first negative electrode active material layer of the stack. The negative electrode layer was prepared through such a process. The thickness of the first negative electrode active material layer included in the negative electrode layer was about 15 μm. The area of the first negative electrode active material layer was equal to the area of the negative electrode current collector.

[0442] (Preparation of positive electrode layer)

[0443] Li2S-C-solid electrolyte composite was prepared as the positive electrode active material. The Li2S-C-solid electrolyte composite was prepared according to the method disclosed in Nano Lett. 2016, 16, 7, pp4521-4527, except that Li6PS5Cl was changed to LiI.

[0444] Prepare Li6PS5Cl (D50 = 3.0 um, crystal) as a argyrodite-type crystal as a solid electrolyte. Prepare KB as a conductive agent. Mix these materials at a weight ratio of positive electrode active material: solid electrolyte: conductive agent of 40:50:10 to prepare a positive electrode mixture. Obtain the positive electrode mixture by dry mixing using a ball mill. The positive electrode mixture obtained by ball milling forms an ion-conductive and electron-conductive network.

[0445] Set the positive electrode mixture on one side of a positive electrode current collector coated with carbon on one side composed of SUS or aluminum foil, and press it flat at a pressure of 200 MPa for 10 minutes to prepare a positive electrode layer. The thickness of the positive electrode layer is about 120 μm. The thickness of the positive electrode active material layer is about 100 μm, and the thickness of the carbon-coated aluminum foil is about 20 μm.

[0446] (Preparation of solid electrolyte layer)

[0447] Prepare a mixture by adding 1.5 parts by weight of an acrylic binder to 98.5 parts by weight of a solid electrolyte as a argyrodite-type crystal of Li6PS5Cl solid electrolyte (D50 = 3.0 mm, crystal). Add octyl acetate to the prepared mixture and stir to prepare a slurry. Apply the prepared slurry to a 15-μm-thick nonwoven fabric placed on a 75-μm-thick PET substrate using a bar coater, and dry it in air at a temperature of 80 °C for 10 minutes to obtain a laminate. Vacuum-dry the obtained laminate at a temperature of 80 °C for 2 hours. Prepare the solid electrolyte layer by such a process.

[0448] (Flame-retardant non-active member)

[0449] Mold a slurry obtained by mixing pulp fibers (cellulose fibers), glass fibers, aluminum hydroxide (Al(OH)3), titanium dioxide (TiO2), an acrylic binder, and a solvent into a washer shape, and then remove the solvent to prepare a flame-retardant non-active member.

[0450] The weight ratio of pulp fibers (cellulose fibers), glass fibers, aluminum hydroxide (Al(OH)3), titanium dioxide (TiO2), and an acrylic binder is 20:8:60:10:2. The thickness of the non-active member is 120 μm.

[0451] Before setting the prepared flame-retardant non-active member on the solid electrolyte layer, perform vacuum heat treatment at a temperature of 80 °C for 5 hours to remove moisture and the like from the flame-retardant non-active member.

[0452] (Manufacture of all-solid-state secondary battery)

[0453] Refer to Figure 1, a solid electrolyte layer is disposed on the negative electrode layer such that the first negative electrode active material layer is in contact with the solid electrolyte layer, and a positive electrode layer is disposed on the solid electrolyte layer. A first gasket is disposed around the negative electrode layer to surround the negative electrode layer and contact the solid electrolyte layer, thereby preparing a stacked body. The thickness of the first gasket is about 120 μm. The above-mentioned flame-retardant non-active member (first non-active member) is used as the first gasket. The negative electrode layer is disposed at the central portion of the solid electrolyte layer, and the first gasket is disposed to surround the negative electrode layer and extend to the end of the solid electrolyte layer. The area of the negative electrode layer is about 90% of the area of the solid electrolyte layer, and the first gasket is disposed in the remaining 10% of the entire area of the solid electrolyte layer where the negative electrode layer is not provided.

[0454] A second gasket is disposed around the positive electrode layer to surround the positive electrode layer and contact the solid electrolyte layer, thereby preparing a stacked body. The thickness of the second gasket is about 120 μm. The above-mentioned flame-retardant non-active member (second non-active member) is used as the second gasket. The positive electrode layer is disposed at the central portion of the solid electrolyte layer, and the second gasket is disposed to surround the positive electrode layer and extend to the end of the solid electrolyte layer. The area of the positive electrode layer is about 80% of the area of the solid electrolyte layer, and the second gasket is disposed in the remaining 20% of the entire area of the solid electrolyte layer where the positive electrode layer is not provided.

[0455] The prepared stacked body is hot-pressed at a temperature of 85 °C and a pressure of 500 MPa for 30 minutes. Through such pressing, the solid electrolyte layer is sintered to improve the battery characteristics. The thickness of the sintered solid electrolyte layer is about 45 μm.

[0456] The pressed stacked body is placed in a bag and vacuum-sealed to manufacture an all-solid-state secondary battery. Portions of the positive electrode current collector and the negative electrode current collector extend to the outside of the sealed battery and are used as the positive electrode layer terminal and the negative electrode layer terminal.

[0457] Example 2: Sulfide-based positive electrode active material (Li2S-C-solid electrolyte composite), first negative electrode active material layer, using a first non-flame-retardant non-active member and a second non-flame-retardant non-active member

[0458] An all-solid-state secondary battery is manufactured in the same manner as in Example 1 except that the first flame-retardant non-active member and the second flame-retardant non-active member are respectively changed to a first non-flame-retardant non-active member and a second non-flame-retardant non-active member.

[0459] The non-flame-retardant non-active member includes pulp fibers and an acrylic binder with a weight ratio of 98:2, and does not include glass fibers, Al(OH)3, and TiO2. The thicknesses of both the first non-flame-retardant non-active member and the second non-flame-retardant non-active member are 120 μm.

[0460] Example 3: Sulfide-based positive electrode active material (Li2S-C-solid electrolyte composite), first negative electrode active material layer (Ag-loaded carbon), using a first flame-retardant inactive member and a second flame-retardant inactive member

[0461] A all-solid-state secondary battery was fabricated in the same manner as in Example 1, except that a CB loaded with silver particles was used instead of a mixture of CB and silver particles as the negative electrode active material.

[0462] (Preparation of CB loaded with silver particles)

[0463] CB was dispersed in a 1.0 M sulfuric acid solution and stirred for 2 hours, then filtered and dried to prepare acid-treated CB.

[0464] 10 g of the acid-treated CB was added to a mixed solvent of 1500 g of distilled water, 1500 g of ethanol, and 30 g of glycerol and stirred, then 2 g of AgNO3 was added and stirred to prepare a mixed solution. The particle size of the CB was 80 nm. A reducing agent was added to the mixed solution, and silver ions were reduced and loaded on the CB. The CB loaded with silver-containing particles was filtered, washed, and dried to prepare a composite negative electrode active material. As a result of scanning electron microscopy and X-ray photoelectron spectroscopy (XPS) measurements, it was confirmed that a plurality of silver-containing particles were loaded on the CB particles. The silver-containing particles included silver particles, silver oxide (AgO) particles, and composite particles of silver (Ag) and silver oxide (AgO). The content of the silver-containing particles included in the composite negative electrode active material was 5 wt%. The average particle size of the silver particles was 10 nm.

[0465] Example 4: Sulfide-based positive electrode active material (Li2S-C composite), first negative electrode active material layer, using a first flame-retardant inactive member and a second flame-retardant inactive member

[0466] A all-solid-state secondary battery was fabricated in the same manner as in Example 1, except that a Li2S-C composite was used instead of a Li2S-C-solid electrolyte composite as the positive electrode active material.

[0467] Except that the vapor-grown carbon fiber (VGCF) was changed to CNF, the Li2S-C composite was prepared according to the method disclosed in Electrochimica Acta 230 (2017) 279-284.

[0468] Comparative Example 1: Sulfide-based positive electrode active material (Li2S-C-solid electrolyte composite), without using the first negative electrode active material layer (no first negative electrode active material layer), without using the first flame-retardant inactive member and the second flame-retardant inactive member (no first flame-retardant inactive member and second flame-retardant inactive member)

[0469] A all-solid-state secondary battery is manufactured in the same manner as in Example 1, except that a second flame-retardant non-active member (second gasket) is not used in the positive electrode layer, only a negative electrode current collector is used in the negative electrode layer, and a first negative electrode active material layer and a first flame-retardant non-active member (first gasket) are not used.

[0470] Comparative Example 2: Sulfide-based positive electrode active material (Li2S-C-solid electrolyte composite), no first negative electrode active material layer (without the first negative electrode active material layer), a second flame-retardant non-active member is used, and a first flame-retardant non-active member is not used (without the first flame-retardant non-active member)

[0471] A all-solid-state secondary battery is manufactured in the same manner as in Example 1, except that a second flame-retardant non-active member (second gasket) is used in the positive electrode layer, only a negative electrode current collector is used in the negative electrode layer, and a first negative electrode active material layer and a first flame-retardant non-active member (first gasket) are not used.

[0472] Comparative Example 3: Sulfide-based positive electrode active material (Li2S-C-solid electrolyte composite), a first negative electrode active material layer is used, a second flame-retardant non-active member is used, and a first flame-retardant non-active member is not used (without the first flame-retardant non-active member)

[0473] A all-solid-state secondary battery is manufactured in the same manner as in Example 1, except that only a second flame-retardant non-active member (second gasket) is used in the positive electrode layer, and a first flame-retardant non-active member (first gasket) is not used in the negative electrode layer.

[0474] Example 5: Dual-cell all-solid-state secondary battery, sulfide-based positive electrode active material (Li2S-C-solid electrolyte composite), a first negative electrode active material layer, a first flame-retardant non-active member and a second flame-retardant non-active member are used

[0475] (Manufacture of dual-cell all-solid-state secondary battery)

[0476] The positive electrode layer is prepared in the same manner as in Example 1, except that the positive electrode active material layer is prepared to be disposed on both sides of the positive electrode current collector.

[0477] The total thickness of the positive electrode layer is about 220 μm. The thickness of each positive electrode active material layer is about 100 μm, and the thickness of the carbon-coated aluminum foil is about 20 μm.

[0478] Two negative electrode layers, two solid electrolyte layers, two first flame-retardant non-active members and two second flame-retardant non-active members are prepared in the same manner as in Example 1.

[0479] Refer to Figure 3, a solid electrolyte layer is disposed on the positive electrode layer such that the positive electrode active material layer is in contact with the solid electrolyte layer, and a negative electrode layer is disposed on the solid electrolyte layer such that the first negative electrode active material layer is in contact with the solid electrolyte layer. The positive electrode layer has a structure in which the positive electrode active material layer is disposed on each of both sides of the positive electrode current collector.

[0480] A second gasket is disposed around the positive electrode layer to surround the positive electrode layer and be in contact with the solid electrolyte layer. The thickness of the second gasket is about 220 μm. The second gasket may have a structure in which two first gaskets each having a thickness of 110 μm are stacked or may be provided as one gasket having a thickness of 220 μm. A second flame-retardant non-active member is used as the second gasket.

[0481] The second gasket is disposed to be in contact with the side surfaces of the positive electrode layer and the solid electrolyte layer. The positive electrode layer is disposed at the central portion of the solid electrolyte layer, and the second gasket is disposed to surround the positive electrode layer and extend to the end portion of the solid electrolyte layer. The area of the positive electrode layer is about 90% of the area of the solid electrolyte layer, and the second gasket is disposed in the remaining 10% of the entire area of the solid electrolyte layer where the positive electrode layer is not provided. The solid electrolyte layer is disposed on the positive electrode layer and the second gasket, and the negative electrode layer is disposed on the solid electrolyte layer to prepare a stacked body.

[0482] A first gasket is disposed around the negative electrode layer to surround the negative electrode layer and be in contact with the solid electrolyte layer. The thickness of the first gasket is about 120 μm. A first flame-retardant non-active member is used as the first gasket.

[0483] The first gasket is disposed to be in contact with the side surfaces of the negative electrode layer and the solid electrolyte layer. The negative electrode layer is disposed at the central portion of the solid electrolyte layer, and the first gasket is disposed to surround the negative electrode layer and extend to the end portion of the solid electrolyte layer. The area of the negative electrode layer is about 90% of the area of the solid electrolyte layer, and the first gasket is disposed in the remaining 10% of the entire area of the solid electrolyte layer where the negative electrode layer is not provided.

[0484] The prepared stacked body is hot-pressed at a temperature of 85 °C and a pressure of 500 MPa for 30 minutes. By such pressing, the solid electrolyte layer is sintered to improve battery characteristics. The thickness of one sintered solid electrolyte layer is about 45 μm. The density of the Li6PS5Cl solid electrolyte, which is a thiogermanate-type crystal included in the sintered solid electrolyte layer, is 1.6 g / cc.

[0485] The pressed stacked body is put into a bag and vacuum-sealed to manufacture an all-solid-state secondary battery. Portions of the positive electrode current collector and the negative electrode current collector are extended to the outside of the sealed battery and used as a positive electrode layer terminal and a negative electrode layer terminal.

[0486] Evaluation Example 1: High-temperature life characteristic test

[0487] The charge / discharge characteristics of the all-solid-state secondary batteries fabricated in Example 1, Example 3, Example 4, and Example 5, and Comparative Example 1 and Comparative Example 2 were evaluated through the following charge / discharge tests. The charge / discharge tests were conducted by placing the all-solid-state secondary batteries in a constant-temperature bath at 45°C.

[0488] In the first cycle, the all-solid-state secondary battery was charged at a constant current of 0.3 mA / cm 2 for 12.5 hours until the battery voltage reached 2.5 V to 2.8 V. Subsequently, the all-solid-state secondary battery was discharged at a constant current of 0.3 mA / cm 2 for 12.5 hours until the battery voltage reached 0.5 V.

[0489] The discharge capacity of the first cycle was taken as the standard capacity. From the second cycle onwards, charging and discharging were carried out under the same conditions as the first cycle. The measurement results are shown in Table 1 below.

[0490] It is considered that after the second cycle, as the number of cycles required for the discharge capacity to decrease to 95% of the standard capacity increases, the life characteristics are improved.

[0491] In the all-solid-state secondary battery of Comparative Example 1, a short circuit occurred before the completion of the first cycle, so the life characteristics could not be measured.

[0492] [Table 1]

[0493]

[0494]

[0495] As shown in Table 1, compared with the all-solid-state secondary battery of Comparative Example 2, the all-solid-state secondary batteries of Example 1 and Example 3 to Example 5 have improved life characteristics.

[0496] The relative superiority of the life characteristics of the all-solid-state secondary batteries is as follows: Example 3 > Example 5 > Example 1 ≒ Example 4 > Comparative Example 2.

[0497] It was confirmed that since the growth of lithium dendrites was suppressed, short circuits were suppressed, and the volume change of the negative electrode layer was suppressed. Therefore, compared with the all-solid-state secondary battery of Comparative Example 2 that does not include the first negative electrode active material layer and the negative electrode gasket, the all-solid-state secondary batteries of Example 1 and Example 3 to Example 5 that include the first negative electrode active material layer and the negative electrode gasket have improved life characteristics.

[0498] It is confirmed that since the volume change during charging or discharging is effectively alleviated due to the dual-cell structure in which each component is symmetrically arranged, the all-solid-state secondary battery of Example 5 has improved life characteristics compared to the all-solid-state secondary batteries of Example 1 and Example 4 having a single-cell structure.

[0499] It is confirmed that since carbon loaded with silver particles is used, the all-solid-state secondary battery of Example 3 has improved life characteristics compared to Example 1, Example 4, and Example 5 using a simple mixture of silver particles and carbon particles.

[0500] Evaluation Example 2: High-temperature stability test

[0501] The life characteristics were evaluated in the same manner as in Evaluation Example 1, except that the all-solid-state secondary batteries manufactured in Example 1, Example 2, and Comparative Example 3 were stored in a thermostat at a temperature of 195 °C for 24 hours, then taken out and placed in a thermostat at a temperature of 45 °C for charge / discharge testing.

[0502] [Table 2]

[0503]

[0504] As shown in Table 2, the all-solid-state secondary battery of Example 1 has significantly improved high-temperature stability compared to the all-solid-state secondary batteries of Example 2 and Comparative Example 3.

[0505] In the all-solid-state secondary battery of Example 1 including a flame-retardant gasket, since the flame-retardant gasket includes a lithium fixative, the lithium fixative reacts with liquid lithium, thereby suppressing the leakage of liquid lithium to the positive electrode. On the other hand, in the all-solid-state secondary battery of Example 2 including a non-flame-retardant gasket and the all-solid-state secondary battery of Comparative Example 3 not including a gasket in the negative electrode, it was confirmed that an internal short circuit occurred due to the leakage of liquid lithium to the positive electrode.

[0506] Example 11: Single-cell all-solid-state secondary battery, sulfide-based positive electrode active material (Li2S-C-solid electrolyte composite), using a lithium host layer, using a first flame-retardant non-active member and a second flame-retardant non-active member

[0507] (Preparation of negative electrode layer)

[0508] A SUS foil with a thickness of 10 μm was prepared as a negative electrode current collector. In addition, a carbonized cotton sheet was prepared as a lithium host. The carbonized cotton sheet was prepared according to the method disclosed in Joule 2017, 1, 563.

[0509] The prepared carbonized cotton sheet was placed on the SUS foil to prepare a stack. The prepared stack was vacuum dried at a temperature of 40 °C for 10 hours. The dried stack was pressed at 5 tf / cm 2Cold roll pressing is carried out at a speed of 5 m / s under pressure to flatten the surface of the lithium host layer of the stacked body. The negative electrode layer is prepared by this method. The thickness of the carbonized cotton sheet included in the negative electrode layer (for example, the thickness of the lithium host layer) is about 120 μm.

[0510] (Preparation of the positive electrode layer)

[0511] Prepare a Li2S-C-solid electrolyte composite as the positive electrode active material. The Li2S-C-solid electrolyte composite is prepared according to the method disclosed in Nano Lett. 2016, 16, 7, pp4521 - 4527, except that Li6PS5Cl is changed to LiI.

[0512] Prepare Li6PS5Cl (D50 = 3.0 μm, crystal) as a solid electrolyte in the form of a thiogermanate crystal. Prepare KB as a conductive agent. Mix these materials in a weight ratio of positive electrode active material: solid electrolyte: conductive agent of 40:50:10 to prepare a positive electrode mixture. The positive electrode mixture is obtained by dry mixing using a ball mill. The positive electrode mixture obtained by ball milling forms an ion-conductive and electron-conductive network.

[0513] Set the positive electrode mixture on one side of a positive electrode current collector coated with carbon on one side composed of SUS or aluminum foil, and flat press it at a pressure of 200 MPa for 10 minutes to prepare the positive electrode layer. The thickness of the positive electrode layer is about 120 μm. The thickness of the positive electrode active material layer is about 100 μm, and the thickness of the carbon-coated aluminum foil is about 20 μm.

[0514] (Preparation of the solid electrolyte layer)

[0515] Prepare a mixture by adding 1.5 parts by weight of an acrylic binder to 98.5 parts by weight of a solid electrolyte as a Li6PS5Cl solid electrolyte (D50 = 3.0 mm, crystal) in the form of a thiogermanate crystal. Add octyl acetate to the prepared mixture and stir to prepare a slurry. Apply the prepared slurry to a 15-μm-thick nonwoven fabric placed on a 75-μm-thick PET substrate using a bar coater, and dry it in air at a temperature of 80 °C for 10 minutes to obtain a stacked body. Vacuum dry the obtained stacked body at a temperature of 80 °C for 2 hours. The solid electrolyte layer is prepared by such a process.

[0516] (Flame-retardant non-active component)

[0517] The slurry obtained by mixing pulp fibers (cellulose fibers), glass fibers, aluminum hydroxide (Al(OH)3), titanium dioxide (TiO2), an acrylic binder, and a solvent is molded into a washer shape, and then the solvent is removed to prepare a flame-retardant non-active component.

[0518] The weight ratio of pulp fiber (cellulose fiber), glass fiber, aluminum hydroxide (Al(OH)3), titanium dioxide (TiO2) and acrylic binder is 20:8:60:10:2. The thickness of the non-active member is 120 μm.

[0519] Before setting the prepared flame-retardant non-active member on the solid electrolyte layer, vacuum heat treatment is carried out at a temperature of 80 °C for 5 hours to remove moisture and the like from the flame-retardant non-active member.

[0520] (Manufacture of all-solid-state secondary battery)

[0521] Refer to Figure 10 , the solid electrolyte layer is set on the negative electrode layer so that the lithium host layer is in contact with the solid electrolyte layer, and the positive electrode layer is set on the solid electrolyte layer. A first gasket is set around the negative electrode layer to surround the negative electrode layer and contact the solid electrolyte layer, thereby preparing a stacked body. The thickness of the first gasket is about 120 μm. The above-mentioned flame-retardant non-active member (first flame-retardant non-active member) is used as the first gasket. The negative electrode layer is set at the central part of the solid electrolyte layer, and the first gasket is set to surround the negative electrode layer and extend to the end of the solid electrolyte layer. The area of the negative electrode layer is about 90% of the area of the solid electrolyte layer, and the first gasket is set in the remaining 10% of the entire area of the solid electrolyte layer where the negative electrode layer is not set.

[0522] A second gasket is set around the positive electrode layer to surround the positive electrode layer and contact the solid electrolyte layer, thereby preparing a stacked body. The thickness of the second gasket is about 120 μm. The above-mentioned flame-retardant non-active member (second flame-retardant non-active member) is used as the second gasket. The positive electrode layer is set at the central part of the solid electrolyte layer, and the second gasket is set to surround the positive electrode layer and extend to the end of the solid electrolyte layer. The area of the positive electrode layer is about 90% of the area of the solid electrolyte layer, and the second gasket is set in the remaining 10% of the entire area of the solid electrolyte layer where the positive electrode layer is not set.

[0523] The prepared stacked body is hot-pressed at a temperature of 85 °C and a pressure of 500 MPa for 30 minutes. Through such pressing, the solid electrolyte layer is sintered to improve battery characteristics. The thickness of the sintered solid electrolyte layer is about 45 μm. The density of the Li6PS5Cl solid electrolyte, which is a thio-LISICON type crystal included in the sintered solid electrolyte layer, is 1.6 g / cc.

[0524] The pressed stacked body is put into a bag and vacuum-sealed to manufacture an all-solid-state secondary battery. Parts of the positive electrode current collector and the negative electrode current collector are extended to the outside of the sealed battery and used as the positive electrode layer terminal and the negative electrode layer terminal.

[0525] Example 12: Sulfide-based positive electrode active material (Li2S-C-solid electrolyte composite), using a lithium host layer, using a first non-flame-retardant non-active member and a second non-flame-retardant non-active member

[0526] A all-solid-state secondary battery is manufactured in the same manner as in Example 11, except that the first flame-retardant non-active member and the second flame-retardant non-active member are respectively changed to a first non-flame-retardant non-active member and a second non-flame-retardant non-active member.

[0527] The non-flame-retardant non-active member includes pulp fibers and an acrylic binder with a weight ratio of 98:2, and does not include glass fibers, Al(OH)3, and TiO2. The thicknesses of both the first non-flame-retardant non-active member and the second non-flame-retardant non-active member are 120 μm.

[0528] Example 13: Sulfide-based positive electrode active material (Li2S-C composite), using a lithium host layer, using a first flame-retardant non-active member and a second flame-retardant non-active member

[0529] A all-solid-state secondary battery is manufactured in the same manner as in Example 11, except that a Li2S-C composite is used instead of a Li2S-C-solid electrolyte composite as the positive electrode active material.

[0530] The Li2S-C composite is prepared according to the method disclosed in Electrochimica Acta 230 (2017) 279-284, except that vapor-grown carbon fiber (VGCF) is changed to CNF.

[0531] Reference Example 11: Sulfide-based positive electrode active material (Li2S-C-solid electrolyte composite), using a lithium host layer, using a second flame-retardant non-active member, not using a first flame-retardant non-active member (without a first flame-retardant non-active member)

[0532] A all-solid-state secondary battery is manufactured in the same manner as in Example 11, except that only the second flame-retardant non-active member (second gasket) is used in the positive electrode layer, and the first flame-retardant non-active member (first gasket) is not used in the negative electrode layer.

[0533] Comparative Example 11: Sulfide-based positive electrode active material (Li2S-C-solid electrolyte composite), not using a lithium host layer (without a lithium host layer), not using a first flame-retardant non-active member and a second flame-retardant non-active member (without a first flame-retardant non-active member and a second flame-retardant non-active member)

[0534] A all-solid-state secondary battery is manufactured in the same manner as in Example 11, except that the second flame-retardant non-active member (second gasket) is not used in the positive electrode layer, only the negative electrode current collector is used in the negative electrode layer, and the lithium host layer and the first flame-retardant non-active member (first gasket) are not used.

[0535] Comparative Example 12: Sulfide-based positive electrode active material (Li2S-C-solid electrolyte composite), without using a lithium host layer (no lithium host layer), without using a first flame-retardant inactive member (no first flame-retardant inactive member)

[0536] A all-solid-state secondary battery is manufactured in the same manner as in Example 11, except that a second flame-retardant inactive member (second gasket) is used in the positive electrode layer, only a negative electrode current collector is used in the negative electrode layer, and a lithium host layer and a first flame-retardant inactive member (first gasket) are not used.

[0537] Example 14: A dual-cell all-solid-state secondary battery, with a sulfide-based positive electrode active material (Li2S-C-solid electrolyte composite), using a lithium host layer, using a first flame-retardant inactive member and a second flame-retardant inactive member

[0538] (Manufacture of dual-cell all-solid-state secondary battery)

[0539] The positive electrode layer is prepared in the same manner as in Example 11, except that the positive electrode active material layer is prepared to be disposed on both sides of the positive electrode current collector.

[0540] The total thickness of the positive electrode layer is about 220 μm. The thickness of each positive electrode active material layer is about 100 μm, and the thickness of the carbon-coated aluminum foil is about 20 μm.

[0541] Two negative electrode layers, two solid electrolyte layers, two first flame-retardant inactive members, and two second flame-retardant inactive members are prepared in the same manner as in Example 11.

[0542] Refer to Figure 12 , the solid electrolyte layer is disposed on the positive electrode layer such that the positive electrode active material layer is in contact with the solid electrolyte layer, and the negative electrode layer is disposed on the solid electrolyte layer such that the lithium host layer is in contact with the solid electrolyte layer. The positive electrode layer has a structure in which the positive electrode active material layer is disposed on each of both sides of the positive electrode current collector.

[0543] A second gasket is disposed around the positive electrode layer to surround the positive electrode layer and is in contact with the solid electrolyte layer. The thickness of the second gasket is about 220 μm. The second gasket may have a structure in which two first gaskets each having a thickness of 110 μm are stacked, or may be disposed as a single gasket having a thickness of 220 μm. The second flame-retardant inactive member is used as the second gasket.

[0544] The second gasket is arranged to be in contact with the side surfaces of the positive electrode layer and the solid electrolyte layer. The positive electrode layer is disposed at the central portion of the solid electrolyte layer, and the second gasket is arranged to surround the positive electrode layer and extend to the end of the solid electrolyte layer. The area of the positive electrode layer is about 90% of the area of the solid electrolyte layer, and the second gasket is disposed in the remaining 10% of the entire area of the solid electrolyte layer where the positive electrode layer is not provided. The solid electrolyte layer is disposed on the positive electrode layer and the second gasket, and the negative electrode layer is disposed on the solid electrolyte layer to prepare a stacked body.

[0545] The first gasket is disposed around the negative electrode layer to surround the negative electrode layer and be in contact with the solid electrolyte layer. The thickness of the first gasket is about 120 μm. The first flame-retardant non-active member is used as the first gasket.

[0546] The first gasket is arranged to be in contact with the side surfaces of the negative electrode layer and the solid electrolyte layer. The negative electrode layer is disposed at the central portion of the solid electrolyte layer, and the first gasket is arranged to surround the negative electrode layer and extend to the end of the solid electrolyte layer. The area of the negative electrode layer is about 90% of the area of the solid electrolyte layer, and the first gasket is disposed in the remaining 10% of the entire area of the solid electrolyte layer where the negative electrode layer is not provided.

[0547] The prepared stacked body is hot-pressed at a temperature of 85 °C and a pressure of 500 MPa for 30 minutes. Through such pressing, the solid electrolyte layer is sintered to improve the battery characteristics. The thickness of one sintered solid electrolyte layer is about 45 μm. The density of the Li6PS5Cl solid electrolyte, which is a argyrodite-type crystal included in the sintered solid electrolyte layer, is 1.6 g / cc.

[0548] The pressed stacked body is put into a bag and vacuum-sealed to manufacture a all-solid-state secondary battery. Parts of the positive electrode current collector and the negative electrode current collector are extended to the outside of the sealed battery and used as the positive electrode layer terminal and the negative electrode layer terminal.

[0549] Evaluation Example 11: High-temperature life characteristic test

[0550] The charge / discharge characteristics of the all-solid-state secondary batteries manufactured in Evaluation Example 11, Example 13 and Example 14, Reference Example 11, and Comparative Example 11 and Comparative Example 12 are evaluated by the following charge / discharge test. The charge / discharge test is carried out by putting the all-solid-state secondary battery into a constant-temperature bath at a temperature of 45 °C.

[0551] For the first cycle, the all-solid-state secondary battery is charged at a constant current of 0.3 mA / cm 2 for 12.5 hours until the battery voltage reaches 2.5 V to 2.8 V. Subsequently, the all-solid-state secondary battery is discharged at a constant current of 0.3 mA / cm 2 for 12.5 hours until the battery voltage reaches 0.5 V.

[0552] The discharge capacity of the first cycle is taken as the standard capacity. From the second cycle onwards, charging and discharging are carried out under the same conditions as the first cycle for 200 cycles. The measurement results are shown in Table 3 below.

[0553] It is considered that after the second cycle, as the number of cycles required for the discharge capacity to decrease to 95% of the standard capacity increases, the life characteristics are improved.

[0554] In the all-solid-state secondary battery of Comparative Example 11, a short circuit occurred before the completion of the first cycle, so the life characteristics could not be measured.

[0555] [Table 3]

[0556]

[0557]

[0558] As shown in Table 3, compared with the all-solid-state secondary battery of Comparative Example 12, the all-solid-state secondary batteries of Example 11, Example 13, and Example 14 have improved life characteristics.

[0559] The relative superiority of the life characteristics of the all-solid-state secondary battery is as follows: Example 14 > Example 11 ≒ Example 13 > Reference Example 11 > Comparative Example 12.

[0560] It was confirmed that, compared with the all-solid-state secondary battery of Comparative Example 12 that does not include a lithium host, the all-solid-state secondary batteries of Example 11, Example 13, and Example 14 and Reference Example 11 that include a lithium host have improved life characteristics because the growth of lithium dendrites is suppressed, so short circuits are suppressed, and the volume change of the negative electrode layer is suppressed.

[0561] It was confirmed that, compared with the all-solid-state secondary batteries of Example 11, Example 13, and Reference Example 11 that have a single-cell structure, the all-solid-state secondary battery of Example 14 has improved life characteristics because the volume change during charging or discharging is effectively reduced due to the dual-cell structure in which each component is symmetrically arranged therein.

[0562] It was confirmed that, compared with Example 12 that includes a non-flame-retardant non-active member, the all-solid-state secondary batteries of Example 11 and Example 13 include a flame-retardant non-active member, so they have improved life characteristics.

[0563] It was confirmed that, compared with Reference Example 11 that does not include a non-active member in the negative electrode layer, the all-solid-state secondary batteries of Example 11 and Example 13 include a non-active member in the negative electrode layer, so they have improved life characteristics.

[0564] Evaluation of Example 12: High-temperature stability test

[0565] Except that the all-solid-state secondary batteries fabricated in Examples 11 and 12 were stored in a thermostat at a temperature of 195°C for 24 hours, then taken out and placed in a thermostat at a temperature of 45°C for charge / discharge testing, the life characteristics were evaluated in the same manner as in Evaluation Example 11.

[0566] [Table 4]

[0567]

[0568]

[0569] As shown in Table 4, compared with the all-solid-state secondary battery of Example 12, the all-solid-state secondary battery of Example 11 has significantly improved high-temperature stability.

[0570] In the all-solid-state secondary battery of Example 11 including a flame-retardant gasket, since the flame-retardant gasket includes a lithium fixative, the lithium fixative reacts with liquid lithium, thereby inhibiting the leakage of liquid lithium to the positive electrode. On the other hand, in the all-solid-state secondary battery of Example 12 including a non-flame-retardant gasket, it was confirmed that an internal short circuit occurred due to the leakage of liquid lithium to the positive electrode.

[0571] As described above, the all-solid-state secondary battery according to the given embodiments can be applied to various portable devices, vehicles, etc.

[0572] Although the exemplary examples have been described in detail with reference to the accompanying drawings, the inventive concept is not limited to the embodiments. It is obvious to those skilled in the art to which the inventive concept pertains that various changes and modifications can be conceived within the scope of the technical idea described in the claims, and those changes and modifications are understood to naturally belong to the technical scope of the inventive concept.

[0573] Description of the reference numerals of the main elements of the designated drawings

[0574] 1: All-solid-state secondary battery; 10: Positive electrode layer

[0575] 11: Positive electrode current collector; 12: Positive electrode active material layer

[0576] 20: Negative electrode layer; 21: Negative electrode current collector

[0577] 22: First negative electrode active material layer; 30: Solid electrolyte layer

[0578] 40: Inactive member; 41: Second inactive member

[0579] 42: First inactive member; 50: Third inactive member.

[0580] Industrial applicability

[0581] According to the all-solid-state secondary battery having a novel structure, an all-solid-state secondary battery in which short circuits are suppressed and cycle characteristics are improved can be provided.

Claims

1. A all-solid-state secondary battery, the all-solid-state secondary battery comprising: a positive electrode layer; a negative electrode layer; and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer, wherein the positive electrode layer includes a positive electrode current collector and a positive electrode active material layer disposed on one or both sides of the positive electrode current collector, the positive electrode active material layer includes a positive electrode active material, the negative electrode layer includes a negative electrode current collector and a first negative electrode active material layer disposed on one side of the negative electrode current collector, and the all-solid-state secondary battery further includes a first inactive member disposed on a side surface of the negative electrode layer.

2. The all-solid-state secondary battery according to claim 1, wherein, The first inactive member surrounds the side surface of the negative electrode layer, contacts the solid electrolyte layer, and is separated from the positive electrode layer.

3. The all-solid-state secondary battery according to claim 1, wherein, The first inactive member extends from the side surface of the negative electrode layer along the surface of the solid electrolyte layer to an end of the solid electrolyte layer.

4. The all-solid-state secondary battery according to claim 1, wherein, The first inactive member extends to be disposed on at least a part of the side surface of the solid electrolyte layer and is separated from the positive electrode layer.

5. The all-solid-state secondary battery according to claim 1, wherein, The thickness of the first inactive member is greater than the thickness of the first negative electrode active material layer, the thickness of the solid electrolyte layer is greater than the thickness of the first negative electrode active material layer, and the area of the negative electrode layer is greater than the area of the positive electrode layer.

6. The all-solid-state secondary battery according to claim 1, wherein The positive electrode layer includes: the positive electrode current collector; and a first positive electrode active material layer and a second positive electrode active material layer respectively disposed on both sides of the positive electrode current collector, the solid electrolyte layer includes a first solid electrolyte layer and a second solid electrolyte layer respectively contacting the first positive electrode active material layer and the second positive electrode active material layer, the negative electrode layer includes a first negative electrode layer and a second negative electrode layer respectively contacting the first solid electrolyte layer and the second solid electrolyte layer, and the all-solid-state secondary battery includes a 1a inactive member disposed on a side surface of the first negative electrode layer and a 1b inactive member disposed on a side surface of the second negative electrode layer.

7. The all-solid-state secondary battery according to claim 1, wherein The first inactive member includes a flame-retardant inactive member, and the flame-retardant inactive member includes a matrix and a filler.

8. The all-solid-state secondary battery according to claim 7, wherein, The matrix includes a substrate and a reinforcing material, the substrate includes a first fiber material, wherein the first fiber material is an insulating material and includes at least one selected from pulp fiber, insulating polymer fiber, and ion-conductive polymer fiber, and the reinforcing material includes a second fiber material, wherein the second fiber material is a flame-retardant material and includes at least one selected from glass fiber and ceramic fiber.

9. The all-solid-state secondary battery according to claim 7, wherein, The filler includes a moisture absorbent, a flame retardant, a lithium fixative, or a combination thereof, the moisture absorbent includes a metal hydroxide, wherein the metal hydroxide includes at least one selected from Mg(OH)2, Fe(OH)3, Sb(OH)3, Sn(OH)4, Ti(OH)3, Zr(OH)4, and Al(OH)3, and the flame retardant includes at least one selected from zinc borate, calcium zinc molybdate complex, MoO3, (NH4)2Mo2O7, Sb2O3, and Sb3O5, and The lithium fixative includes a metal oxide, wherein the metal oxide includes at least one selected from TiO2, ZrO2, HfO2, and ThO2.

10. The all-solid-state secondary battery according to claim 1, wherein, The first negative electrode active material layer is a metal layer, and the metal layer includes lithium or a lithium alloy.

11. The all-solid-state secondary battery according to claim 1, wherein, The ratio (B / A) of the initial charge capacity (B) of the first negative electrode active material layer to the initial charge capacity (A) of the positive electrode active material layer is in the range of 0.005 to 0.45, and The first negative electrode active material layer includes a negative electrode active material and a binder, wherein the negative electrode active material has a particulate form and an average particle diameter of 4 μm or less.

12. The all-solid-state secondary battery according to claim 11, wherein, The negative electrode active material includes at least one selected from carbon-based negative electrode active materials and metal-based negative electrode active materials, The carbon-based negative electrode active material includes amorphous carbon, crystalline carbon, porous carbon, or a combination thereof, and The metal-based negative electrode active material includes gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), zinc (Zn), or a combination thereof.

13. The all-solid-state secondary battery according to claim 11, wherein, The negative electrode active material includes: a carbon-based carrier; and a metal-based negative electrode active material supported on the carbon-based carrier, The metal-based negative electrode active material includes a metal, a metal oxide, a composite of a metal and a metal oxide, or a combination thereof, and has a particulate form and a particle diameter of 1 nm to 200 nm, The carbon-based carrier has a particulate form and a particle diameter of 10 nm to 2 μm, and the all-solid-state secondary battery further includes a second negative electrode active material layer disposed between the negative electrode current collector and the first negative electrode active material layer after charging, and The second negative electrode active material layer is a metal layer including lithium or a lithium alloy.

14. The all-solid-state secondary battery according to claim 1, wherein the all-solid-state secondary battery further includes a third inactive member disposed on the other side of the negative electrode current collector, Among them, The third inactive member includes a conductive flame-retardant inactive member.

15. The all-solid-state secondary battery according to claim 1, wherein, The positive electrode active material includes a lithium-containing oxide-based positive electrode active material, and The lithium-containing oxide-based positive electrode active material includes at least one selected from lithium transition metal oxides represented by the following formulas 1 to 8: Formula 1 Li a Ni x Co y M z O 2-b A b Wherein, in Formula 1, 1.0 ≤ a ≤ 1.2, 0 ≤ b ≤ 0.2, 0.8 ≤ x < 1, 0 ≤ y ≤ 0.3, 0 < z ≤ 0.3, and x + y + z = 1, M is manganese (Mn), niobium (Nb), vanadium (V), magnesium (Mg), gallium (Ga), silicon (Si), tungsten (W), molybdenum (Mo), iron (Fe), chromium (Cr), copper (Cu), zinc (Zn), titanium (Ti), aluminum (Al), boron (B), or a combination thereof, and A is F, S, Cl, Br, or a combination thereof; Formula 2 LiNi x Co y Mn z O2 Formula 3 LiNi x Co y Al z O2 In Formulas 2 and 3, 0.8 ≤ x ≤ 0.95, 0 ≤ y ≤ 0.2, 0 < z ≤ 0.2, and x + y + z = 1; Formula 4 LiNi x Co y Mn z Al w O2 In Formula 4, 0.8 ≤ x ≤ 0.95, 0 ≤ y ≤ 0.2, 0 < z ≤ 0.2, 0 < w ≤ 0.2, and x + y + z + w = 1; Formula 5 Li a Co x M y O 2-b A b In Formula 5, 1.0 ≤ a ≤ 1.2, 0 ≤ b ≤ 0.2, 0.9 ≤ x ≤ 1, 0 ≤ y ≤ 0.1, and x + y = 1, M is manganese (Mn), niobium (Nb), vanadium (V), magnesium (Mg), gallium (Ga), silicon (Si), tungsten (W), molybdenum (Mo), iron (Fe), chromium (Cr), copper (Cu), zinc (Zn), titanium (Ti), aluminum (Al), boron (B) or a combination thereof, and A is F, S, Cl, Br or a combination thereof; Formula 6 Li a Ni x Mn y M' z O 2-b A b In Formula 6, 1.0 ≤ a ≤ 1.2, 0 ≤ b ≤ 0.2, 0 < x ≤ 0.3, 0.5 ≤ y < 1, 0 < z ≤ 0.3, and x + y + z = 1, M' is cobalt (Co), niobium (Nb), vanadium (V), magnesium (Mg), gallium (Ga), silicon (Si), tungsten (W), molybdenum (Mo), iron (Fe), chromium (Cr), copper (Cu), zinc (Zn), titanium (Ti), aluminum (Al), boron (B) or a combination thereof, and A is F, S, Cl, Br or a combination thereof; Formula 7 Li a M1 x M2 y PO 4-b X b In Formula 7, 0.90 ≤ a ≤ 1.1, 0 ≤ x ≤ 0.9, 0 ≤ y ≤ 0.5, 0.9 < x + y < 1.1, and 0 ≤ b ≤ 2, M1 is chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zirconium (Zr) or a combination thereof, M2 is magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), titanium (Ti), zinc (Zn), boron (B), niobium (Nb), gallium (Ga), indium (In), molybdenum (Mo), tungsten (W), aluminum (Al), silicon (Si), chromium (Cr), vanadium (V), scandium (Sc), yttrium (Y) or a combination thereof, and X is O, F, S, P or a combination thereof; and Formula 8 Li a M3 z PO4 In Formula 8, 0.90 ≤ a ≤ 1.1, 0.9 ≤ z ≤ 1.1, and M3 is chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zirconium (Zr) or a combination thereof.

16. The all-solid-state secondary battery according to claim 1, wherein, The positive electrode active material includes a lithium-containing sulfide-based positive electrode active material, The lithium-containing sulfide-based positive electrode active material includes a Li2S-containing composite, The Li2S-containing composite includes: a composite of Li2S and carbon; a composite of Li2S, carbon and a solid electrolyte; a composite of Li2S and a solid electrolyte; a composite of Li2S and a metal carbide; a composite of Li2S, carbon and a metal carbide; a composite of Li2S and a metal nitride; a composite of Li2S, carbon and a metal nitride; or a combination thereof, and The positive electrode active material layer further includes FeS2, VS2, NaS, MnS, FeS, NiS, CuS or a combination thereof.

17. The all-solid-state secondary battery according to claim 1, wherein The positive electrode active material layer further includes at least one selected from a solid electrolyte, a conductive material and a binder, The solid electrolyte includes a sulfide-based solid electrolyte, and the conductive material includes a carbon-based conductive material, The all-solid-state secondary battery further includes a second inactive member disposed on a side surface of the positive electrode layer, and Part or all of the second inactive member is provided to be spaced apart from the side surface of the positive electrode active material layer.

18. The all-solid-state secondary battery according to claim 1, wherein, The solid electrolyte layer includes an electrolyte, The electrolyte includes a solid electrolyte, a gel electrolyte, or a combination thereof, The solid electrolyte includes a sulfide-based solid electrolyte, an oxide-based solid electrolyte, a polymer solid electrolyte, or a combination thereof, The gel electrolyte includes a polymer gel electrolyte, and The solid electrolyte layer is impermeable to polysulfide lithium.

19. The all-solid-state secondary battery according to claim 1, wherein, The sulfide-based solid electrolyte includes at least one selected from the following: Li2S-P2S5; Li2S-P2S5-LiX, where X is a halogen element; Li2S-P2S5-Li2O; Li2S-P2S5-Li2O-LiI; Li2S-SiS2; Li2S-SiS2-LiI; Li2S-SiS2-LiBr; Li2S-SiS2-LiCl; Li2S-SiS2-B2S3-LiI; Li2S-SiS2-P2S5-LiI; Li2S-B2S3; Li2S-P2S5-Z m S n , where m and n are each positive numbers, and Z is one of Ge, Zn, and Ga; Li2S-GeS2; Li2S-SiS2-Li3PO4; Li2S-SiS2-Li p MO q , where p and q are each positive numbers, and M is one of P, Si, Ge, B, Al, Ga, and In; Li 7-x PS 6-x Cl x , where 0 ≤ x ≤ 2; Li 7-x PS 6-x Br x , where 0 ≤ x ≤ 2; and Li 7-x PS 6-x I x , where 0 ≤ x ≤ 2.

20. The all-solid-state secondary battery according to claim 1, wherein, At least one of the positive electrode current collector and the negative electrode current collector includes a substrate film and a metal layer provided on one or both sides of the substrate film, The substrate film includes a polymer, wherein, The polymer includes polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polybutylene terephthalate (PBT), polyimide (PI), or a combination thereof, and The metal layer includes indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), or an alloy thereof.

21. A all-solid-state secondary battery, the all-solid-state secondary battery comprising: A positive electrode layer; A negative electrode layer; And A solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer, Wherein, the positive electrode layer includes a positive electrode current collector and a positive electrode active material layer provided on one or both sides of the positive electrode current collector, The positive electrode active material layer includes a lithium-containing sulfide-based positive electrode active material, the lithium-containing sulfide-based positive electrode active material includes Li2S, a Li2S-containing composite, or a combination thereof, The negative electrode layer includes a negative electrode current collector and a lithium host layer provided on one side of the negative electrode current collector, The lithium host layer includes a lithium host structure, The lithium host structure includes one or more lithium hosts, the lithium host includes a carbon-based lithium host, a metal-based lithium host, a polymer-based lithium host, or a combination thereof, and The all-solid-state secondary battery further includes a first inactive member disposed on a side surface of the negative electrode layer.

22. The all-solid-state secondary battery according to claim 21, wherein, The lithium host structure includes a one-dimensional structure, a two-dimensional structure, a three-dimensional structure, or a combination thereof, Wherein, the one-dimensional structure includes a one-dimensional nanostructure, a one-dimensional microstructure, or a combination thereof, The two-dimensional structure includes a two-dimensional nanostructure, a two-dimensional microstructure, or a combination thereof, The three-dimensional structure includes a three-dimensional nanostructure, a three-dimensional microstructure, or a combination thereof, and The lithium host structure includes a porous structure, a non-porous structure, or a combination thereof, and includes a particulate structure, a sheet structure, a paper structure, a non-woven fabric structure, a woven fabric structure, a foam structure, a network structure, or a combination thereof.

23. The all-solid-state secondary battery according to claim 21, wherein, The carbon-based lithium host includes amorphous carbon, crystalline carbon, porous carbon, non-porous carbon, or a combination thereof, and includes carbon black (CB), acetylene black (AB), furnace black (FB), Ketjen black (KB), graphene, graphene oxide, reduced graphene oxide, carbon fiber, carbon nanotube (CNT), carbon nanobelt, carbon paper, carbon sheet, foam carbon, or a combination thereof.

24. The all-solid-state secondary battery according to claim 21, wherein the all-solid-state secondary battery further comprises a coating provided on the carbonaceous lithium host or a dopant doped into the carbonaceous lithium host, Among them, wherein the coating is a lithiophilic layer or a protective layer, wherein the lithiophilic layer comprises a lithiophilic material, wherein the lithiophilic material comprises a lithiophilic metal, a lithiophilic metal oxide, a lithiophilic metal phosphate, a lithiophilic metal nitride, a lithiophilic metal oxynitride, a lithiophilic metal carbide, a lithiophilic metal-organic framework, a lithiophilic metal chalcogenide, or a combination thereof, wherein the lithiophilic metal comprises gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), zinc (Zn), or an alloy thereof, wherein the lithiophilic metal oxide comprises gold oxide, platinum oxide, palladium oxide, silicon oxide, silver oxide, aluminum oxide, bismuth oxide, tin oxide, manganese oxide, zinc oxide, or a combination thereof, wherein the protective layer comprises a protective material, wherein the protective material comprises an organic material, an inorganic material, an organic-inorganic composite material, or a combination thereof, wherein the dopant comprises a heteroatom, and wherein the heteroatom comprises nitrogen (N), oxygen (O), phosphorus (P), boron (B), sulfur (S), fluorine (F), chlorine (Cl), bromine (Br), germanium (Ge), gallium (Ga), or a combination thereof.

25. The all-solid-state secondary battery according to claim 21, wherein, The metal-based lithium host comprises a metal, a metal oxide, a metal phosphate, a metal nitride, a metal oxynitride, a metal carbide, a metal-organic framework, a metal chalcogenide, or a combination thereof, wherein the metal comprises copper (Cu), nickel (Ni), stainless steel (SUS), titanium (Ti), iron (Fe), cobalt (Co), or an alloy thereof, wherein the metal oxide comprises copper oxide, zinc oxide, nickel oxide, titanium oxide, iron oxide, cobalt oxide, ruthenium oxide, iridium oxide, platinum oxide, manganese oxide, tin oxide, indium oxide, or a combination thereof, wherein the metal phosphate comprises copper phosphate, nickel phosphate, titanium phosphate, iron phosphate, cobalt phosphate, ruthenium phosphate, iridium phosphate, platinum phosphate, manganese phosphate, tin phosphate, indium phosphate, or a combination thereof, wherein the metal nitride comprises titanium nitride, tungsten nitride, thallium nitride, titanium aluminum nitride, thallium silicon nitride, titanium silicon nitride, ruthenium titanium nitride, or a combination thereof, wherein the metal oxynitride comprises copper oxynitride, nickel oxynitride, titanium oxynitride, iron oxynitride, cobalt oxynitride, ruthenium oxynitride, iridium oxynitride, platinum oxynitride, manganese oxynitride, tin oxynitride, indium oxynitride, or a combination thereof, wherein the metal carbide comprises copper carbide, nickel carbide, titanium carbide, iron carbide, cobalt carbide, ruthenium carbide, iridium carbide, platinum carbide, manganese carbide, tin carbide, indium carbide, or a combination thereof, wherein the metal-organic framework (MOF) comprises Co-embedded N-doped carbon (Co-NC, ZIF-67), Zn-embedded N-doped carbon (Zn-NC, ZIF-8), or a combination thereof, and wherein the metal chalcogenide comprises molybdenum disulfide, molybdenum diselenide, molybdenum ditelluride, tungsten disulfide, tungsten diselenide, tungsten ditelluride, or a combination thereof.

26. The all-solid-state secondary battery according to claim 21, wherein the all-solid-state secondary battery further comprises a coating provided on the lithium-like metal host or a dopant doped into the lithium-like metal host, Among them, the coating is a lithium-philic layer or a protective layer, the lithium-philic layer comprises a lithium-philic material, the protective layer comprises a protective material, and the dopant comprises a p-type dopant or an n-type dopant.

27. The all-solid-state secondary battery according to claim 21, wherein, The polymer-like lithium host comprises an insulating polymer, an ion-conductive polymer, an electron-conductive polymer, or a combination thereof, and the all-solid-state secondary battery further comprises a coating provided on the polymer-like lithium host or polar functional groups provided on the surface of the polymer-like lithium host, wherein the coating is a lithium-philic layer or a protective layer, the lithium-philic layer comprises a lithium-philic material, the protective layer comprises a protective material, and the polar functional groups comprise hydroxyl groups, nitrile groups, or a combination thereof.

28. The all-solid-state secondary battery according to claim 21, wherein, The lithium host comprises a conductive lithium host, a non-conductive lithium host, or a combination thereof, and comprises an electrochemically inert lithium host, an electrochemically active lithium host, or a combination thereof.

29. The all-solid-state secondary battery according to claim 21, wherein The lithium host layer further comprises pores, and the pores comprise first pores provided in the lithium host, interstitial second pores between a plurality of lithium hosts, or a combination thereof.

30. The all-solid-state secondary battery according to claim 29, wherein the all-solid-state secondary battery further comprises lithium metal or lithium alloy provided in some or all of the pores provided in the pores after the all-solid-state secondary battery is charged.

31. The all-solid-state secondary battery according to claim 21, wherein, The thickness of the lithium host layer exceeds 50% of the thickness of the positive electrode active material layer or the thickness of the solid electrolyte layer.

32. The all-solid-state secondary battery according to claim 21, wherein the all-solid-state secondary battery further comprises an intermediate layer provided between the lithium host layer and the solid electrolyte layer and / or between the lithium host layer and the negative electrode current collector, Among them, the intermediate layer comprises a binder.

33. The all-solid-state secondary battery according to claim 21, wherein, The first non-active member surrounds the side surface of the lithium host layer and contacts the solid electrolyte layer, or surrounds the side surfaces of the lithium host layer and the negative electrode current collector and contacts the solid electrolyte layer, the first non-active member extends from the side surface of the lithium host layer along the surface of the solid electrolyte layer to the end of the solid electrolyte layer, the area of the lithium host layer is smaller than the area of the solid electrolyte layer in contact with the lithium host layer, and the first non-active member is provided to surround the side surface of the lithium host layer to compensate for the area difference between the lithium host layer and the solid electrolyte layer.

34. The all-solid-state secondary battery according to claim 21, wherein, The positive electrode layer comprises the positive electrode current collector and a first positive electrode active material layer and a second positive electrode active material layer respectively provided on both sides of the positive electrode current collector, the solid electrolyte layer comprises a first solid electrolyte layer and a second solid electrolyte layer respectively in contact with the first positive electrode active material layer and the second positive electrode active material layer, the negative electrode layer comprises a first negative electrode layer and a second negative electrode layer respectively in contact with the first solid electrolyte layer and the second solid electrolyte layer, the first negative electrode layer comprises a first negative electrode current collector and a first lithium host layer, the second negative electrode layer comprises a second negative electrode current collector and a second lithium host layer, and The first inactive member is disposed to surround each of the side surfaces of the first lithium host layer and the second lithium host layer between the first solid electrolyte layer and the first negative current collector and between the second solid electrolyte layer and the second negative current collector.

35. The all-solid-state secondary battery according to claim 21, wherein, The first inactive member includes a flame-retardant inactive member, The flame-retardant inactive member includes a matrix and a filler, wherein the matrix includes a substrate and a reinforcing material, the substrate includes a first fiber material, wherein the first fiber material is an insulating material and includes at least one selected from pulp fiber, insulating polymer fiber, and ion-conductive polymer fiber, and the reinforcing material includes a second fiber material, wherein the second fiber material is a flame-retardant material and includes at least one selected from glass fiber and ceramic fiber, the filler is a moisture absorbent or a lithium fixing agent, the moisture absorbent includes a metal hydroxide, wherein the metal hydroxide includes at least one selected from Mg(OH)2, Fe(OH)3, Sb(OH)3, Sn(OH)4, Ti(OH)3, Zr(OH)4, and Al(OH)3, and the lithium fixing agent includes a metal oxide, wherein the metal oxide includes at least one selected from TiO2, ZrO2, HfO2, and ThO2.

36. The all-solid-state secondary battery according to claim 21, wherein, The Li2S-containing composite includes: a composite of Li2S and carbon; a composite of Li2S, carbon, and a solid electrolyte; a composite of Li2S and a solid electrolyte; a composite of Li2S and a metal carbide; a composite of Li2S, carbon, and a metal carbide; a composite of Li2S and a metal nitride; a composite of Li2S, carbon, and a metal nitride; or a combination thereof, and The positive electrode active material layer further includes FeS2, VS2, NaS, MnS, FeS, NiS, CuS, or a combination thereof.

37. The all-solid-state secondary battery according to claim 21, wherein, At least one of the positive current collector and the negative current collector includes a base film and a metal layer provided on one or both sides of the base film, The base film includes a polymer, wherein, the polymer includes polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polybutylene terephthalate (PBT), polyimide (PI), or a combination thereof, and the metal layer includes indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), or an alloy thereof.

38. The all-solid-state secondary battery according to claim 21, wherein, The positive electrode active material layer further includes at least one selected from a solid electrolyte, a conductive material, and a binder, wherein the solid electrolyte includes a sulfide-based solid electrolyte, and the conductive material includes a carbon-based conductive material.

39. The all-solid-state secondary battery according to claim 21, wherein the all-solid-state secondary battery further includes a second inactive member disposed adjacent to a side surface of the positive electrode active material layer, Among them, A part or all of the second inactive member is disposed at a distance from the side surface of the positive electrode active material layer.

40. The all-solid-state secondary battery according to claim 21, wherein The solid electrolyte layer includes an electrolyte, The electrolyte includes a solid electrolyte, a gel electrolyte, or a combination thereof, the solid electrolyte includes a sulfide-based solid electrolyte, an oxide-based solid electrolyte, a polymer solid electrolyte, or a combination thereof, the gel electrolyte includes a polymer gel electrolyte, and the solid electrolyte layer is impermeable to polysulfide lithium.

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