All-solid-state secondary battery

Abstract

Provided is an all-solid-state secondary battery comprising: a positive electrode layer; a negative electrode layer; and a solid electrolyte layer arranged between the positive electrode layer and the negative electrode layer, wherein the positive electrode layer includes a positive electrode active material layer, and the negative electrode layer includes a negative electrode current collector and a first negative electrode active material layer disposed between the negative electrode current collector and the solid electrolyte layer. The first negative electrode active material layer includes a first negative electrode active material and a second negative electrode active material. The first negative electrode active material includes a lithium metal oxide, a metal oxide, or a combination thereof, and the second negative electrode active material includes a metal-based negative electrode active material, a carbon-based negative electrode active material, or a combination thereof.

Description

All-solid-state secondary battery

[0001] This is about all-solid-state secondary batteries.

[0002] Recently, there has been active development of batteries that provide increased energy density and safety. Lithium batteries are used in information devices, communication devices, and automobiles. Safety is critical for automobiles because they are related to human life. Lithium batteries containing liquid electrolytes include flammable organic solvents. Lithium batteries containing liquid electrolytes have a high risk of overheating and fire in the event of a short circuit. Solid electrolytes have a reduced risk of overheating and fire in the event of a short circuit compared to liquid electrolytes. Lithium batteries containing solid electrolytes can provide enhanced safety compared to lithium batteries containing liquid electrolytes.

[0003] One aspect is to provide an all-solid-state secondary battery with improved cycle characteristics, particularly high-rate characteristics, by improving the uniformity of the lithium precipitation reaction and suppressing the precipitation of lithium dendrites.

[0004] Depending on one aspect

[0005] It comprises an anode layer; a cathode layer; and a solid electrolyte layer disposed between the anode layer and the cathode layer,

[0006] The above anode layer includes an anode active material layer,

[0007] The above cathode layer comprises a cathode current collector; and a first cathode active material layer disposed between the cathode current collector and the solid electrolyte layer, and

[0008] The above first negative electrode active material layer comprises a first negative electrode active material and a second negative electrode active material, and

[0009] The first negative electrode active material comprises a lithium metal oxide, a metal oxide, or a combination thereof, and

[0010] An all-solid-state secondary battery is provided, wherein the second negative electrode active material comprises a metal-based negative electrode active material, a carbon-based negative electrode active material, or a combination thereof.

[0011] According to one aspect, a new all-solid-state secondary battery can be provided with improved cycle characteristics, particularly high-rate characteristics, by improving the uniformity of the lithium precipitation reaction and suppressing the precipitation of lithium dendrites.

[0012] Figure 1 is a scanning electron microscope image of a mixture of the first cathode active material and the second cathode active material prepared in Preparation Example 1.

[0013] Figure 2 is a Nyquist plot showing the impedance measurement results for the all-solid-state secondary batteries prepared in Example 4 and Comparative Example 2.

[0014] Figure 3 is a graph showing the measurement results of the lithiation potential for the all-solid-state secondary batteries prepared in Example 4 and Comparative Example 2.

[0015] Figure 4 is a graph showing the overpotential measurement results for the all-solid-state secondary batteries prepared in Examples 4 to 6 and Comparative Example 2.

[0016] Figure 5a is a graph showing the GITT (Galvanostatic Intermittent Titration Technique) measurement results for the all-solid-state secondary batteries prepared in Example 4 and Comparative Example 2 with respect to capacity.

[0017] Figure 5b is an enlarged view of the boxed portion of Figure 5a.

[0018] FIG. 5c is a graph showing the GITT (Galvanostatic Intermittent Titration Technique) measurement results for the all-solid-state secondary batteries prepared in Example 4 and Comparative Example 2 against measurement time.

[0019] Figure 6 is a graph showing the high-rate characteristic measurement results for the all-solid-state secondary batteries prepared in Example 1 and Comparative Example 1.

[0020] FIG. 7 is a cross-sectional view of an all-solid-state secondary battery according to an exemplary embodiment.

[0021] FIG. 8 is a cross-sectional view of an all-solid-state secondary battery according to an exemplary embodiment.

[0022] FIG. 9 is a cross-sectional view of a mono-cell all-solid-state secondary battery according to an exemplary embodiment.

[0023] FIG. 10 is a cross-sectional view of a mono-cell all-solid-state secondary battery according to an exemplary embodiment.

[0024] FIG. 11 is a cross-sectional view of a bi-cell all-solid-state secondary battery according to an exemplary embodiment.

[0025] <Explanation of symbols for major parts of the drawing>

[0026] 1, 1a All-solid-state secondary battery 10 Cathode layer

[0027] 11 Anode current collector 12, 12a, 12b Anode active material layer

[0028] 20, 20a, 20b cathode layers 21, 21a, 21b cathode current collector

[0029] 22, 22a, 22b First cathode active material layer 23 Second cathode active material layer

[0030] 30, 30a, 30b solid electrolyte layers 40, 40a, 40b inert member

[0031] Various embodiments are illustrated in the accompanying drawings. However, the present creative concept may be embodied in many different forms and should not be interpreted as being limited to the embodiments described herein. Rather, these embodiments are provided to ensure that the present disclosure is thorough and complete and will sufficiently convey the scope of the present creative concept to those skilled in the art. Identical reference numerals denote identical components.

[0032] When it is stated that one component is "on top" of another component, it can be understood that it may be directly on top of the other component or that another component may be interposed between them. In contrast, when it is stated that a component is "directly on top" of another component, no component is interposed between them.

[0033] Terms such as "first," "second," "third," etc., may be used in this specification to describe various components, components, regions, layers, and / or zones, but these components, components, regions, layers, and / or zones should not be limited by these terms. These terms are used solely to distinguish one component, component, region, layer, or zone from another. Accordingly, the first component, component, region, layer, or zone described below may be referred to as the second component, component, region, layer, or zone without departing from the teachings of this specification.

[0034] The terms used herein are intended to describe specific embodiments only and are not intended to limit the creative idea. The singular form used herein is intended to include the plural form including "at least one" unless the content clearly indicates otherwise. "At least one" should not be interpreted as limiting to the singular. As used herein, the term "and / or" includes any combination of one or more of the listed items. The terms "comprising" and / or "comprising" as used in the detailed description specify the presence of the specified features, regions, integers, steps, actions, components, and / or components, and do not exclude the presence or addition of one or more other features, regions, integers, steps, actions, components, components, and / or groups thereof.

[0035] Spatially relative terms such as "bottom," "lower," "subordinate," "top," "upper," and "upper" may be used herein to facilitate the description of the relationship of one component or feature to another component or feature. Spatially relative terms are to be understood as intended to include different orientations of the device during use or operation in addition to the orientations depicted in the drawings. For example, if the device in the drawings is inverted, a component described as "bottom" or "lower" of another component or feature will be oriented to the "top" of that other component or feature. Thus, the exemplary term "bottom" may encompass both the upper and lower directions. The device may be positioned in different directions (it may be rotated 90 degrees or rotated in other directions), and spatially relative terms used herein may be interpreted accordingly.

[0036] Unless otherwise defined, all terms used in this specification (including technical and scientific terms) have the same meaning as generally understood by those skilled in the art to which this disclosure pertains. Furthermore, it will also be understood that terms as defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning within the context of the relevant technology and the content of this disclosure, and should not be interpreted in an idealized or overly formal sense.

[0037] Exemplary embodiments are described herein with reference to cross-sectional views, which are schematic diagrams of idealized embodiments. As such, variations from the depicted shapes should be expected as a result of, for example, manufacturing techniques and / or tolerances. Accordingly, the embodiments described herein should not be interpreted as being limited to the specific shapes of the regions as depicted herein, but should include variations in shapes resulting from, for example, manufacturing. For example, a region depicted or described as flat may typically have rough and / or non-linear features. Furthermore, an angle depicted as sharp may be rounded. Accordingly, the regions depicted in the drawings are essentially schematic, and the shapes are not intended to depict the exact shape of the region and are not intended to limit the scope of the claims.

[0038] "Group" refers to a group of elements in the periodic table according to the International Union of Pure and Applied Chemistry ("IUPAC") group classification system of groups 1-18.

[0039] In this specification, "particle diameter" refers to the average diameter when the particles are spherical and the average major axis length when the particles are non-spherical. The particle diameter can be measured using a particle size analyzer (PSA). "Particle diameter" is, for example, the average particle diameter. The "average particle diameter" is, for example, D50, the median particle diameter.

[0040] D50 is the particle size corresponding to 50% of the cumulative volume calculated from the side of the particle with the smaller particle size in the particle size distribution measured by laser diffraction.

[0041] D90 is the particle size corresponding to the 90% cumulative volume calculated from the side of the particle with the smaller particle size in the particle size distribution measured by laser diffraction.

[0042] D10 is the particle size corresponding to the 10% cumulative volume calculated from the side of the particle with the smaller particle size in the particle size distribution measured by laser diffraction.

[0043] In the present disclosure, “metal” includes both metals and metalloids such as silicon and germanium in an elemental or ionic state.

[0044] In the present disclosure, "alloy" refers to a metallic material comprising two or more elements, one or more of which is the metal described above.

[0045] In the present disclosure, "electrode active material" refers to an electrode material capable of undergoing lithiation and delithiation.

[0046] In the present disclosure, "anode active material" refers to an anode material capable of undergoing lithiation and delithiation.

[0047] In the present disclosure, "anode active material" refers to an anode material capable of undergoing lithiation and delithiation.

[0048] In the present disclosure, "lithiation" and "to lithiate" refer to the process of adding lithium to an electrode active material.

[0049] In the present disclosure, "delithiation" and "to delithiate" refer to the process of removing lithium from an electrode active material.

[0050] In this disclosure, "charge" and "to charge" refer to the process of providing electrochemical energy to a battery.

[0051] In this disclosure, "discharge" and "discharge" refer to the process of removing electrochemical energy from a battery.

[0052] In this disclosure, "anode" and "cathode" refer to electrodes where electrochemical reduction and lithiation occur during the discharge process.

[0053] In this disclosure, "cathode" and "anode" refer to electrodes where electrochemical oxidation and delithiation occur during the discharge process.

[0054] Although specific embodiments have been described, alternatives, modifications, variations, improvements, and substantial equivalents that are not currently anticipated or cannot be anticipated may arise to the applicant or those skilled in the art. Accordingly, the appended claims, which may be filed and modified, are intended to include all such alternatives, modifications, variations, improvements, and substantial equivalents.

[0055] A solid-state secondary battery according to exemplary embodiments is described in more detail below.

[0056] [All-solid-state secondary battery]

[0057] An all-solid-state secondary battery according to one embodiment comprises 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 comprises a positive electrode active material layer. The negative electrode layer comprises a negative electrode current collector; and a first negative electrode active material layer disposed between the negative electrode current collector and the solid electrolyte layer. The first negative electrode active material layer comprises a first negative electrode active material and a second negative electrode active material. The first negative electrode active material comprises a lithium metal oxide, a metal oxide, or a combination thereof. The second negative electrode active material comprises a metal-based negative electrode active material, a carbon-based negative electrode active material, or a combination thereof.

[0058] By including the first negative electrode active material layer, an additional lithium ion conduction path may be formed within the first negative electrode active material layer. The first negative electrode active material layer may have improved lithium ion conductivity, thereby improving the reversibility of the electrode reaction. Consequently, the high-rate characteristics of the all-solid-state secondary battery may be improved.

[0059] By including the first negative electrode active material layer, the uniformity of the lithium precipitation reaction within the first negative electrode active material layer can be improved. Additionally, side reactions between lithium and the solid electrolyte within the first negative electrode active material layer can be suppressed. Accordingly, the growth of lithium dendrites can be suppressed within the first negative electrode active material layer and / or between the first negative electrode active material layer and the solid electrolyte layer.

[0060] Since the first negative electrode active material layer includes the first negative electrode active material, the lithium nucleation overpotential in the first negative electrode active material layer can be reduced. Therefore, the lithium precipitation reaction in the first negative electrode active material layer can be carried out more easily.

[0061] By including the first negative electrode active material layer, the diffusivity or diffusion coefficient of lithium ions in the first negative electrode active material layer can be increased. Since the conduction of lithium ions within the first negative electrode active material layer proceeds more easily, the possibility of lithium precipitation between the first negative electrode active material layer and the solid electrolyte layer can be reduced. Consequently, side reactions between precipitated lithium and the solid electrolyte, namely the formation of a resistance layer due to the reduction of the solid electrolyte, can be effectively suppressed. Furthermore, the interfacial resistance between the first negative electrode active material layer and the solid electrolyte layer can be reduced. As a result, the internal resistance of the all-solid-state secondary battery can be reduced.

[0062] Referring to FIGS. 7 through 11, an all-solid-state secondary battery (1) comprises 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) comprises a positive electrode active material layer (12). The negative electrode layer (20) comprises a negative electrode current collector (21); and a first negative electrode active material layer (22) disposed between the negative electrode current collector (21) and the solid electrolyte layer (30). The first negative electrode active material layer (22) comprises a first negative electrode active material and a second negative electrode active material. The first negative electrode active material comprises a lithium metal oxide, a metal oxide, or a combination thereof. The second negative electrode active material comprises a metal-based negative electrode active material, a carbon-based negative electrode active material, or a combination thereof.

[0063] [Cathode layer]

[0064] [Cathode layer: First cathode active material]

[0065] Referring to FIGS. 7 to 11, the cathode layer (20) includes a first cathode active material layer (22). The first cathode active material layer (22) includes a first cathode active material.

[0066] The first negative electrode active material comprises a lithium metal oxide, a metal oxide, or a combination thereof.

[0067] Lithium metal oxide is, for example, a lithium metal oxide that can be lithiated by lithium ions. Lithium metal oxide is, for example, a lithium metal oxide having lithium ion conductivity. Lithium metal oxide may include, for example, metals belonging to groups 2 through 14 of the periodic table. Lithium metal oxide may include, for example, lithium transition metal oxide. Lithium transition metal oxide may include, for example, transition metals belonging to groups 3 through 12 of the periodic table. Lithium metal oxide is, for example, Li a M b O cIt can be expressed as, and in the above formula 0 <a≤10, 0<b≤10 및 0<c≤20 일 수 있으며, 상기 M은 원소 주기율표 제2 족 내지 제14 족에 속하는 금속일 수 있다. 리튬금속산화물은 예를 들어 티타늄, 지르코늄, 망간, 몰리브덴, 바나듐, 마그네슘, 실리콘, 철, 아연, 주석, 니켈 또는 이들의 조합을 포함할 수 있다. 리튬금속산화물은 예를 들어 Li 4+x Ti5O 12+y (-1≤x≤3, -0.5≤y≤0.5), Li x Fe3O4(0≤x≤2), Li x It may include TiO2 (0≤x≤1) or a combination thereof. Lithium metal oxides are, for example, Li4Ti5O 12 It may include.

[0068] The metal oxide is a metal oxide that can be lithiated by, for example, lithium ions. The metal oxide is, for example, a metal oxide having lithium ion conductivity. The metal oxide may include, for example, metals belonging to Groups 2 through 14 of the periodic table. The metal oxide may include, for example, transition metal oxides. The transition metal oxide may include, for example, transition metals belonging to Groups 3 through 12 of the periodic table. The metal oxide is, for example, M d O e It can be expressed as, and in the above formula 0 <d≤5, 0<e≤6 일 수 있으며, 상기 M은 원소 주기율표 제2 족 내지 제14 족에 속하는 금속일 수 있다. 금속산화물은 예를 들어 티타늄, 지르코늄, 망간, 몰리브덴, 바나듐, 마그네슘, 실리콘, 철, 아연, 주석, 니켈 또는 이들의 조합을 포함할 수 있다. 금속산화물은 예를 들어 TiO2, ZrO2, MnO2, MoO2, V2O5, MgO, SiO2, SiO x (0 <x<2), Fe3O4, ZnO, SnO2, NiO 또는 이들의 조합을 포함할 수 있다.

[0069] The first lithiation potential of the first negative electrode active material may be higher than, for example, the second lithiation potential of the second negative electrode active material. The lithiation potential may be determined, for example, by the position of the peak from the profile of the rate of change of capacity (dQ / dV) according to voltage (V) during the initial charging of an all-solid-state secondary battery. For the method of measuring the lithiation potential, refer to, for example, Evaluation Example 3. Since the first lithiation potential is higher than the second lithiation potential, the first negative electrode active material is lithiated at a higher potential than the second negative electrode active material during the charging process, so the first negative electrode active material may be lithiated before the second negative electrode active material. As the first negative electrode active material is lithiated before the second negative electrode active material, a lithium ion conduction path may be added within the first negative electrode active material layer. Accordingly, the lithiation of the second cathode active material can be performed more easily by adding lithium ions supplied from the lithiated first cathode active material in addition to the lithium ions supplied from the solid electrolyte layer within the first cathode active material layer. The reversibility of the electrode reaction within the first cathode active material layer can be improved. As a result, the high-rate characteristics of the all-solid-state secondary battery can be improved.

[0070] The difference between the first lithiation potential of the first metal oxide and the second lithiation potential of the second negative electrode active material may be, for example, 0.4 V or more, 0.6 V or more, 0.8 V or more, or 1.0 V or more. By having a difference of 0.4 V or more between the first lithiation potential and the second lithiation potential, additional lithium ion conduction pathways can be more easily added within the first negative electrode active material layer.

[0071] The first lithiation potential of the first negative electrode active material is, for example, 1 V (vs. Li + / Li) or higher, 1.2 V (vs. Li + / Li) or higher or 1.4 V (vs. Li+ It may be greater than / Li). The first lithiation potential of the first negative electrode active material is, for example, 1 to 2 V (vs. Li + / Li), 1.2 to 2 V (vs. Li + / Li) or 1.4 to 2 V (vs. Li + / Li) may be possible. As the first cathode active material has this first lithiation potential, an additional lithium ion conduction path can be easily added within the first cathode active material layer.

[0072] The second lithium potential of the second negative electrode active material is, for example, 0.5 V (vs. Li + / Li) or less, 0.3 V (vs. Li + / Li) or less or 0.1 V (vs. Li + It may be less than / Li). The second lithiation potential of the second negative electrode active material is, for example, 0.01 to 0.5 V (vs. Li + / Li), 0.01 to 0.3 V (vs. Li + / Li) or 0.01 to 0.1 V (vs. Li + / Li) can be.

[0073] The lithiation potential of the first negative electrode active material layer (22) is, for example, 40 mV (vs. Li + / Li) exceeding 42 mV (vs. Li + / Li) or higher or 44 mV (vs. Li + / Li) or higher. The lithiation potential of the first negative electrode active material layer (22) is, for example, greater than 40 to 60 mV (vs. Li + / Li), 42 to 55 mV (vs. Li + / Li) or 42 to 50 mV (vs. Li + / Li) may be possible. By having the first negative electrode active material layer (22) have a lithium potential in this range, the high rate characteristics of the all-solid-state secondary battery can be further improved.

[0074] The lithium nucleation overpotential of the first negative electrode active material layer (22) is, for example, 30 mV (vs. Li + / Li) or less, 25 mV (vs. Li + / Li) or less or 20 mV (vs. Li + It may be less than / Li). The lithium nucleation overpotential of the first negative electrode active material layer (22) is, for example, 1 to 30 mV (vs. Li + / Li), 1 to 25 mV (vs. Li + / Li) or 1 to 20 mV (vs. Li + / Li) may be possible. By having the first negative electrode active material layer (22) have a lithium nucleation overpotential in this range, the high rate characteristics of the all-solid-state secondary battery can be further improved. For example, the method of measuring the lithium nucleation overpotential of the first negative electrode active material layer (22) can refer to Evaluation Example 4.

[0075] The content of the first negative electrode active material may be, for example, 0.1 to 5 wt%, 0.1 to 3 wt%, or 0.2 to 2 wt% with respect to the total weight of the first negative electrode active material and the second negative electrode active material. By having the first negative electrode active material in this range, the high-rate characteristics of the all-solid-state secondary battery containing the first negative electrode active material can be further improved.

[0076] The first negative electrode active material may have a particle form, for example. The particle size of the first negative electrode active material is, for example, 5 μm or less, 4 μm or less, 3 μm or less, or 2 μm or less. The particle size of the first negative electrode active material is, for example, 0.1 to 5 μm, 0.2 to 4 μm, 0.3 to 3 μm, or 0.4 to 2 μm or less. By having a particle size within this range, the first negative electrode active material can more easily perform reversible absorption and / or desorption of lithium during charging and discharging. The particle size of the first negative electrode active material is, for example, the average particle size of the first negative electrode active material. The average particle size of the first negative electrode active material may be, for example, a median diameter (D50) measured using a laser particle size distribution meter. Alternatively, the particle size of the first cathode active material can be measured, for example, using a scanning electron microscope.

[0077] The aspect ratio of the first negative electrode active material is, for example, 5 or less, 4 or less, 3 or less, or 2 or less. The aspect ratio of the first negative electrode active material is, for example, 1 to 5, 1 to 4, 1 to 3, or 1 to 2. By having an aspect ratio within this range, the first negative electrode active material can be distributed more uniformly within the first negative electrode active material layer (22). Non-uniformity of volume change during charging and discharging of the first negative electrode active material can be suppressed. The aspect ratio of the first negative electrode active material can be measured, for example, by a scanning electron microscope. By having an aspect ratio within this range, the high-rate characteristics of the all-solid-state secondary battery containing the first negative electrode active material can be further improved.

[0078] [Cathode layer: Second cathode active material]

[0079] Referring to FIGS. 7 to 11, the cathode layer (20) includes a first cathode active material layer (22). The first cathode active material layer (22) includes a second cathode active material.

[0080] The second negative electrode active material may have a particle form, for example. The particle size of the second negative electrode active material is, for example, less than 1 μm, 500 nm or less, 300 nm or less, or 100 nm or less. The particle size of the second negative electrode active material is, for example, 10 nm to less than 1 μm, 10 nm to 900 nm, 10 nm to 700 nm, 10 nm to 500 nm, 10 nm to 300 nm, 10 nm to 200 nm, or 10 nm to 100 nm. By having a particle size within this range, the second negative electrode active material can more easily perform reversible absorption and / or desorption of lithium during charging and discharging. The particle size of the second negative electrode active material is, for example, the average particle size of the second negative electrode active material. The average particle size of the second cathode active material may be, for example, the median diameter (D50) measured using a laser particle size distribution meter. Alternatively, the particle size of the second cathode active material may be measured, for example, using a scanning electron microscope.

[0081] The aspect ratio of the second negative electrode active material is, for example, 5 or less, 4 or less, 3 or less, or 2 or less. The aspect ratio of the second negative electrode active material is, for example, 1 to 5, 1 to 4, 1 to 3, or 1 to 2. By having an aspect ratio within this range, the second negative electrode active material can be distributed more uniformly within the first negative electrode active material layer (22). Non-uniformity of volume change during charging and discharging of the second negative electrode active material can be suppressed. The aspect ratio of the second negative electrode active material can be measured, for example, by a scanning electron microscope. By having an aspect ratio within this range, the high-rate characteristics of the all-solid-state secondary battery containing the second negative electrode active material can be further improved.

[0082] The particle size of the second negative electrode active material may be, for example, smaller than the particle size of the first negative electrode active material. The particle size of the second negative electrode active material may be, for example, 50% or less, 30% or less, 20% or less, or 10% or less of the particle size of the first negative electrode active material. The particle size of the second negative electrode active material may be, for example, 1 to 50%, 2 to 30%, 3 to 20% or less, or 4 to 10% of the particle size of the first negative electrode active material. By having the particle size of the second negative electrode active material within this range relative to the particle size of the first negative electrode active material, the high-rate characteristics of the all-solid-state secondary battery including the first negative electrode active material layer can be further improved.

[0083] The second cathode active material includes a metal-based cathode active material, a carbon-based cathode active material, or a combination thereof.

[0084] Metal-based negative electrode active materials may include, for example, a metal capable of forming an alloy with lithium or a metal capable of forming a compound with lithium. Metal-based negative electrode active materials may include, for example, zinc (Zn), gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), iridium (Ir), osmium (Os), rhodium (Rh), ruthenium (Ru), or a combination thereof. For example, nickel (Ni) does not form an alloy with lithium and therefore is not included in the metal-based negative electrode active materials of this specification.

[0085] Carbon-based cathode active materials include, for example, amorphous carbon, crystalline carbon, porous carbon, or a combination thereof. The carbon-based cathode active material is, for example, amorphous carbon. Amorphous carbon may include, for example, carbon black (CB), acetylene black (AB), furnace black (FB), ketjen black (KB), graphene, or a combination thereof. Amorphous carbon is carbon that does not possess crystallinity or has very low crystallinity, and is distinguished from crystalline carbon or graphite-based carbon. The degree of grystalllinity of the carbon-based cathode active material is, for example, the intensity of the peak attributed to crystalline carbon in the XRD spectrum of the carbon-based material (I crystalline ) and the intensity of the peak attributed to amorphous carbon (I amorphous It can be calculated from the percentage of ). If the above percentage value is low, it is carbon with low crystallinity. The carbon-based cathode active material may be, for example, porous carbon. The pore volume contained in the porous carbon is, for example, 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 contained in the porous carbon is, for example, 1 nm to 50 nm, 1 nm to 30 nm, or 1 nm to 10 nm. The BET specific surface area of ​​the porous carbon is, for example, 100 m² 2 / g to 3000 m 2 / g. The average pore size and BET specific surface area of ​​porous carbon can be measured, for example, by the nitrogen gas adsorption method.

[0086] The first negative electrode active material layer (22) may include a type of second negative electrode active material among these second negative electrode active materials, or may include a mixture of multiple different second negative electrode active materials. The first negative electrode active material layer (22) may include, for example, only amorphous carbon. Alternatively, the first negative electrode active material layer (22) may include zinc (Zn), gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), iridium (Ir), osmium (Os), rhodium (Rh), ruthenium (Ru), or a combination thereof. Alternatively, the first negative electrode active material layer (22) comprises a mixture of amorphous carbon and zinc (Zn), gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), iridium (Ir), osmium (Os), rhodium (Rh), ruthenium (Ru), or a combination thereof. The mixing ratio of the mixture of a carbon-based negative electrode active material, such as amorphous carbon, and a metal-based negative electrode active material, such as zinc, may be, for example, 99:1 to 1:99, 10:1 to 1:2, 5:1 to 1:1, or 4:1 to 2:1 by weight. By having the second negative electrode active material have such a composition, the high rate characteristics of the all-solid-state secondary battery (1) can be further improved.

[0087] The first negative electrode active material layer (22) includes a second negative electrode active material, and the second negative electrode active material may include a mixture of a first particle made of amorphous carbon and a second particle made of a metal-based negative electrode active material. The second metal-based negative electrode active material includes, for example, gold (Au), platinum (Pt), palladium (Pd), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). The content of the second particle is 1 to 60 weight%, 8 to 60 weight%, 10 to 50 weight%, 15 to 40 weight%, or 20 to 30 weight% based on the total weight of the mixture of the first particle and the second particle. By having the second particle in this range, the cycle characteristics of the all-solid-state secondary battery (1) can be further improved.

[0088] Alternatively, the first negative electrode active material layer (22) may include, for example, a composite negative electrode active material. The composite negative electrode active material may include, for example, a carbon-based support and a third negative electrode active material supported on the carbon-based support. In the composite negative electrode active material, the third negative electrode active material may be supported on the carbon-based support to form a composite. The composite of the third negative electrode active material and the carbon-based support is distinguished from a simple mixture of the third negative electrode active material and the carbon-based support. By having such a structure, the aggregation and / or localization of the third negative electrode active material within the first negative electrode active material layer (22) is prevented, and a uniform distribution can be obtained. Consequently, the cycle characteristics of the all-solid-state secondary battery (1) including the first negative electrode active material layer (22) can be further improved. The third negative electrode active material supported on the carbon-based support includes, for example, a metal, a metal oxide, a composite of a metal and a metal oxide, or a combination thereof. Metals include, for example, gold (Au), platinum (Pt), palladium (Pd), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), tellurium (Te), and zinc (Zn). Metal oxides include, for example, gold (Au) oxide, platinum (Pt) oxide, palladium (Pd) oxide, silver (Ag) oxide, aluminum (Al) oxide, bismuth (Bi) oxide, tin (Sn) oxide, tellurium (Te) oxide, and zinc (Zn) oxide. Metal oxides include, for example, Au x O y (0 <x≤2, 0<y≤3), Pt x O y (0 <x≤1, 0<y≤2), Pd x O y (0 <x≤1, 0<y≤1), Ag x O y (0 <x≤2, 0<y≤1), Al x O y (0 <x≤2, 0<y≤3), Bi x O y (0 <x≤2, 0<y≤3), Sn x O y (0 <x≤1, 0<y≤2), Tex The y (0 <x≤1, 0<y≤3), Zn x The y (0 <x≤1, 0<y≤1) 또는 이들의 조합을 포함할 수 있다. 금속과 금속산화물의 복합체는 예를 들어 Au와 Au x The y (0 <x≤2, 0<y≤3)의 복합체, Pt와 Pt x The y (0 <x≤1, 0<y≤2)의 복합체, Pd와 Pd x The y (0 <x≤1, 0<y≤1)의 복합체, Ag 와 Ag x The y (0 <x≤2, 0<y≤1)의 복합체, Al과 Al x The y (0 <x≤2, 0<y≤3)의 복합체, Bi와 Bi x The y (0 <x≤2, 0<y≤3)의 복합체, Sn과 Sn x The y (0 <x≤1, 0<y≤2)의 복합체, Te과 Te x The y (0 <x≤1, 0<y≤3), Zn과 Zn x The y(0<x≤1, 0<y≤1)의 복합체, 또는 이들의 조합을 포함할 수 있다. 탄소계 지지체는 예를 들어 비정질 탄소(amorphous carbon)이다. 비정질 탄소는 예를 들어 카본 블랙(carbon black, CB), 아세틸렌 블랙(acetylene black, AB), 퍼니스 블랙(furnace black, FB), 켓젠 블랙(ketjen black, KB), 그래핀(graphene) 활성탄(activated carbon), 등이나 반드시 이들로 한정되지 않으며 당해 기술분야에서 비정질 탄소로 분류되는 것이라면 모두 가능하다. 비정질 탄소는 결정성을 가지지 않거나 결정성이 매우 낮은 탄소로서 결정성 탄소 또는 흑연계 탄소와 구분된다. 복합음극활물질은 예를 들어 입자 형태를 가질 수 있다. 입자 형태를 가지는 복합음극활물질의 입경은 예를 들어, 10 nm 내지 2 ㎛, 10 nm 내지 1 ㎛, 10 nm 내지 500 nm, 10 nm 내지 200 nm 또는 10 nm 내지 100nm 이다. 복합음극활물질이 이러한 범위의 입경을 가짐에 의하여 충방전 시에 리튬의 가역적인 흡장(absorbing) 및 / 또는 방출(desorbing)이 더욱 용이할 수 있다. 지지체 상에 담지된 제3 음극활물질은 예를 들어 입자 형태를 가질 수 있다. 제3 음극활물질의 입경은 예를 들어 1 nm 내지 200 nm, 1 nm 내지 150 nm, 5 nm 내지 100 nm, 또는 10 nm 내지 50 nm 일 수 있다. 탄소계 지치체는 예를 들어 입자 형태를 가질 수 있다. 탄소계 지지체의 입경은 예를 들어 10 nm 내지 2 ㎛, 10 nm 내지 1 ㎛, 10 nm 내지 500 nm, 10 nm 내지 200 nm 또는 10 nm 내지 100 nm 일 수 있다. 탄소계 지지체가 이러한 범위의 입경을 가짐에 의하여 제1 음극활물질층 내에 보다 균일하게 배치될 수 있다. 탄소계 지지체는 예를 들어 입경 500 nm 이하의 나노입자일 수 있다.The particle size of the composite cathode active material, the particle size of the third cathode active material, and the particle size of the carbon-based support are, for example, average particle sizes. The average particle size is, for example, the median diameter (D50) measured using a laser particle size distribution meter. Alternatively, the average particle size can be measured, for example, by an electron microscope.

[0089] [Cathode layer: Binder]

[0090] The first negative electrode active material layer (22) includes a binder. The binder is, for example, a polymer binder. The polymer binder included in the first negative electrode active material layer (22) may be, for example, styrene-butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, vinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, polymethyl methacrylate, etc., but is not necessarily limited to these, and any binder used in the relevant technical field is possible. The binder may be composed of a single binder or a plurality of different binders. The polymer binder may include, for example, a fluorine-based binder.

[0091] The first negative active material layer (22) is stabilized on the negative current collector (21) by including a binder. Additionally, cracking of the first negative active material layer (22) is suppressed despite changes in volume and / or relative position of the first negative active material layer (22) during the charging and discharging process. For example, if the first negative active material layer (22) does not include a binder, it is possible for the first negative active material layer (22) to be easily separated from the negative current collector (21). As the first negative active material layer (22) is separated from the negative current collector (21), the possibility of a short circuit occurring increases as the negative current collector (21) comes into contact with the solid electrolyte layer (30) in the exposed portion of the negative current collector (21). The first negative electrode active material layer (22) is manufactured by, for example, applying a slurry in which the material constituting the first negative electrode active material layer (22) is dispersed onto a negative electrode current collector (21) and drying it. By including a binder in the first negative electrode active material layer (22), stable dispersion of the negative electrode active material and the fibrous carbon-based material in the slurry is possible. For example, when applying the slurry onto the negative electrode current collector (21) using a screen printing method, it is possible to suppress clogging of the screen (for example, clogging caused by aggregates of the negative electrode active material).

[0092] The binder content may be 0.1 to 20 parts by weight, 0.1 to 15 parts by weight, 1 to 10 parts by weight, or 5 to 10 parts by weight per 100 parts by weight of the mixture of the first negative electrode active material and the second negative electrode active material. By having a binder content within this range, the high-rate characteristics of the all-solid-state secondary battery (1) can be further improved.

[0093] [Cathode layer: Other additives]

[0094] The first negative electrode active material layer (22) may further include additives used in conventional all-solid-state secondary batteries (1), such as fillers, coating agents, dispersants, ion-conducting aids, etc.

[0095] [Cathode layer: First cathode active material layer]

[0096] The ratio (B / A) of the initial charge capacity (B) of the first negative electrode active material layer (22) and the initial charge capacity (A) of the positive electrode active material layer (12) may be, for example, 0.001 to 0.45, 0.005 to 0.4, 0.01 to 0.3, 0.01 to 0.2, or 0.01 to 0.1. The initial charge capacity of the positive electrode active material layer (12) is the first open circuit voltage (1 st From open circuit voltage) Li / Li + The initial charging capacity of the first negative electrode active material layer (22) is determined by charging up to the maximum charging voltage. nd From open circuit voltage) Li / Li + It is determined by charging up to 0.01 V. The maximum charging voltage is determined by the type of cathode active material. The maximum charging 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, or 4.3 V. For example, the maximum charging voltage of Li2S or Li2S composites is Li / Li + For this, it can be determined to be between 2.5 and 3.0 V. For example, the maximum charging voltage of a lithium transition metal oxide is Li / Li + It can be determined between 3.0 and 4.5 V.

[0097] The initial charge capacity (mAh) of the positive active material layer (12) is obtained by multiplying the charge specific capacity (mAh / g) of the positive active material by the mass (g) of the positive active material in the positive active material layer (12). If multiple types of positive active materials are used, the charge specific capacity × mass value is calculated for each positive active material, and the sum of these values ​​is the initial charge capacity of the positive active material layer (12). The initial charge capacity of the first negative active material layer (22) is calculated in the same way. The initial charge capacity of the first negative active material layer (22) is obtained by multiplying the charge specific capacity (mAh / g) of the negative active material by the mass of the negative active material in the first negative active material layer (22). If multiple types of negative active materials are used, the charge specific capacity × mass value is calculated for each negative active material, and the sum of these values ​​is the initial charge capacity of the first negative active material layer (22). The charge capacity density of each of the positive active material and the negative active material can be measured using an all-solid-state half-cell using lithium metal as the counter electrode. The initial charge capacity of each of the positive active material layer (12) and the first negative active material layer (22) is at a constant current density, for example, 0.1 mA / cm² 2 This can be directly measured using an all-solid-state half-cell. For the anode, the measurement is taken from the first open-circuit voltage (OCV) to the maximum charging voltage, e.g., 3.0 V (vs. Li / Li). + It can be performed for an operating voltage up to ). For the cathode, the measurement can be performed for an operating voltage from the second open circuit voltage (OCV) down to 0.01 V for the cathode, e.g., lithium metal. For example, an all-solid-state half-electrode having a positive electrode active material layer 0.1 mA / cm² from the first open circuit voltage up to 3.0 V. 2 It can be charged with a constant current. The all-solid-state half-paper having the first negative electrode active material layer can be charged at 0.1 mA / cm² from the second open circuit voltage up to 0.01 V. 2It can be charged with a constant current. The current density during constant current charging is, for example, 0.2 mA / cm² 2 , or 0.5 mA / cm 2 It may be. An all-solid-state half battery having a positive active material layer may be charged, for example, from a first open-circuit voltage to 2.5 V, 2.0 V, 3.5 V, 4.0 V, or 4.5 V. The maximum charging voltage of the positive active material layer may be determined by the maximum voltage of the battery satisfying safety conditions according to JISC8712:2015 of the Japanese Standards Association.

[0098] If the initial charge capacity of the first negative electrode active material layer (22) is excessively small, the thickness of the first negative electrode active material layer (22) becomes very thin, and thus, during repeated charge and discharge processes, lithium dendrites formed between the first negative electrode active material layer (22) and the negative electrode current collector (21) may collapse the first negative electrode active material layer (22), making it difficult to improve the cycle characteristics of the all-solid-state secondary battery (1). If the charge 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) caused by the first negative electrode active material layer (22) increases, making it difficult to improve the cycle characteristics of the all-solid-state secondary battery (1).

[0099] 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 positive electrode active material layer (12). The thickness of the first negative electrode active material layer (22) is, for example, 1 to 50%, 1 to 40%, 1 to 30%, 1 to 20%, or 1 to 10% 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, 1 to 50 μm, 2 to 40 μm, 3 to 30 μm, 4 to 20 μm, or 5 μm to 20 μm. If the thickness of the first negative electrode active material layer (22) is excessively thin, lithium dendrites formed between the first negative electrode active material layer (22) and the negative electrode current collector (21) may 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). If 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) due to the first negative electrode active material layer (22) increases, making it difficult to improve the cycle characteristics of the all-solid-state secondary battery (1). If the thickness of the first negative electrode active material layer (22) decreases, for example, the initial charge capacity of the first negative electrode active material layer (22) also decreases.

[0100] [Cathode layer: Second cathode active material layer]

[0101] Referring to FIG. 8, the all-solid-state secondary battery (1) may further include a second negative electrode active material layer (23) disposed, for example, between a negative electrode current collector (21) and a first negative electrode active material layer (22) after charging. The second negative electrode active material layer (23) is a metal layer containing lithium or a lithium alloy. Therefore, since the second negative electrode active material layer (23) is a metal layer containing lithium, it acts as, for example, a lithium reservoir. The lithium alloy is, for example, 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 is not limited to these, and any alloy used as a lithium alloy in the relevant technical field is possible. The second negative electrode active material layer (23) may be composed of one of these alloys or lithium, or may be composed of various types of alloys. The second negative electrode active material layer (23) is, for example, a plated layer. The second negative electrode active material layer (23) is, for example, deposited between the first negative electrode active material layer (22) and the negative electrode current collector (21) during the charging process of the all-solid-state secondary battery (1).

[0102] The thickness of the second negative electrode active material layer (23) is not particularly limited, but, for example, 1 to 200 μm, 1 to 150 μm, 1 to 100 μm, 1 to 50 μm, 1 to 30 μm, 1 to 22 μm, or 1 μm to 10 μm. If the thickness of the second negative electrode active material layer (23) is excessively thin, it is difficult for the second negative electrode active material layer (23) to perform the role of a lithium reservoir. If the thickness of the second negative electrode active material layer (23) is excessively thick, the mass and volume of the all-solid-state secondary battery (1) increase, and there is a possibility that the cycle characteristics of the all-solid-state secondary battery (1) may deteriorate.

[0103] The thickness of the second negative electrode active material layer (23) may be, for example, smaller than the thickness of the first negative electrode active material layer (22). The thickness of the second negative electrode active material layer (23) may be, for example, 70% or less, 60% or less, 50% or less, 40% or less, or 30% or less of the thickness of the first negative electrode active material layer (22). The thickness of the second negative electrode active material layer (23) may be, for example, 1 to 70%, 1 to 60%, 1 to 50%, 1 to 40%, or 1 to 30% of the thickness of the first negative electrode active material layer (22). As the thickness of the second negative electrode active material layer (23) becomes smaller than the thickness of the first negative electrode active material layer (22), volume change during charging and discharging of the all-solid-state secondary battery can be suppressed. Consequently, degradation due to volume change of the all-solid-state secondary battery can be suppressed.

[0104] Alternatively, in the all-solid-state secondary battery (1), the second negative electrode active material layer (23) may be placed between the negative electrode current collector (21) and the first negative electrode active material layer (22) before assembly of the all-solid-state secondary battery (1), for example. When the second negative electrode active material layer (23) is placed between the negative electrode current collector (21) and the first negative electrode active material layer (22) before assembly of the all-solid-state secondary battery (1), the second negative electrode active material layer (23) acts as a lithium reservoir because it is a metal layer containing lithium. For example, a lithium foil may be placed between the negative electrode current collector (21) and the first negative electrode active material layer (22) before assembly of the all-solid-state secondary battery (1).

[0105] When the second negative electrode active material layer (23) is precipitated by charging after assembly of the all-solid-state secondary battery (1), the energy density of the all-solid-state secondary battery (1) increases because the second negative electrode active material layer (23) is not included during assembly of the all-solid-state secondary battery (1). When charging the all-solid-state secondary battery (1), it is charged in excess of the charging capacity of the first negative electrode active material layer (22). That is, the first negative electrode active material layer (22) is overcharged. At the beginning of charging, lithium is absorbed in the first negative electrode active material layer (22). The negative electrode active material contained in the first negative electrode active material layer (22) forms an alloy or compound with lithium ions that have moved from the positive electrode (10). When charging is performed beyond the capacity of the first negative electrode active material layer (22), lithium is deposited, for example, on the back surface of the first negative electrode active material layer (22), that is, between the negative 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 (23) is formed by the deposited lithium. The second negative electrode active material layer (23) is a metal layer composed mainly of lithium (i.e., metallic lithium). This result is obtained, for example, by the negative electrode active material included in the first negative electrode active material layer (22) including a material that forms an alloy or compound with lithium. During discharge, the lithium in the first negative electrode active material layer (22) and the second negative electrode active material layer (23), i.e., the metal layer, is ionized and moves toward the positive electrode (10). Therefore, it is possible to use lithium as a negative electrode active material in an all-solid-state secondary battery (1). In addition, since the first negative electrode active material layer (22) covers the second negative electrode active material layer (23), it serves as a protective layer for the second negative electrode active material layer (23), i.e., the metal layer, and at the same time, it performs the role of suppressing the precipitation growth of lithium dendrites. Therefore, it suppresses short circuits and capacity degradation of the all-solid-state secondary battery (1), and consequently improves the cycle characteristics of the all-solid-state secondary battery (1).Additionally, when the second negative electrode active material layer (23) is formed by charging after assembly of the all-solid-state secondary battery (1), the negative electrode (20), that is, the negative electrode current collector (21), the first negative electrode active material layer (22), and the region between them are Li-free regions that do not contain lithium (Li) in the initial state or after complete discharge of the all-solid-state secondary battery (1).

[0106] [Cathode layer: Cathode current collector]

[0107] The negative electrode current collector (21) is composed of a material that does not react with, for example, lithium, that is, does not form any alloys or compounds. The material constituting the negative electrode current collector (21) may be, for example, copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), and nickel (Ni), but is not necessarily limited to these; any material used as an electrode current collector in the relevant technical field is acceptable. The negative electrode current collector (21) may be composed of one of the metals described above, or may be composed of an alloy or coating material of two or more metals. The negative electrode current collector (21) is, for example, in the form of a plate or foil.

[0108] Although not shown in the drawing, the all-solid-state secondary battery (1) may further include a thin film containing an element capable of forming an alloy with lithium on one surface of the negative electrode current collector (21). The thin film is disposed between the negative electrode current collector (21) and the first negative electrode active material layer (22). The thin film contains, for example, an element capable of forming an alloy with lithium. The element capable of forming an alloy with lithium is, for example, gold, silver, zinc, tin, indium, silicon, aluminum, bismuth, etc., but is not necessarily limited to these, and any element capable of forming an alloy with lithium in the relevant technical field is possible. The thin film is composed of one of these metals or is composed of an alloy of various types of metals. By placing a thin film on one side of a negative electrode current collector (21), the deposition pattern of the second negative electrode active material layer (23) deposited between, for example, the thin film and the first negative electrode active material layer (22) is further flattened, and the cycle characteristics of the all-solid-state secondary battery (1) can be further improved. The thickness of the thin film is, for example, 1 nm to 800 nm, 10 nm to 700 nm, 50 nm to 600 nm, or 100 nm to 500 nm. If the thickness of the thin film is less than 1 nm, it may be difficult to perform the function of the thin film. If the thickness of the thin film is excessively thick, the thin film itself absorbs lithium, and the amount of lithium deposited at the negative electrode decreases, which lowers the energy density of the all-solid-state battery and may lower the cycle characteristics of the all-solid-state secondary battery (1). The thin film can be placed on the negative current collector (21) by, for example, vacuum deposition, sputtering, plating, etc., but is not necessarily limited to these methods, and any method capable of forming a thin film in the relevant technical field is possible.

[0109] Although not shown in the drawing, the negative 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 be, for example, a thermoplastic polymer. The polymer may include, for example, polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polybutylene terephthalate (PBT), polyimide (PI), or a combination thereof. The polymer may be an insulating polymer. By including an insulating thermoplastic polymer in the base film, the base film may soften or liquefy upon the occurrence of a short circuit, thereby blocking battery operation and suppressing a sudden increase in current. The metal layer may include, for example, copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), or an alloy thereof. The negative current collector (21) may additionally include a metal piece and / or a lead tab. For more specific details regarding the base film, metal layer, metal chip, and lead tab of the negative electrode current collector (21), refer to the positive electrode current collector (11) described above. By having this structure, the negative electrode current collector (21) can reduce the weight of the negative electrode and, consequently, improve the energy density of the negative electrode and the lithium battery.

[0110] [Solid Electrolyte Layer]

[0111] [Solid Electrolyte Layer: Solid Electrolyte]

[0112] Referring to FIGS. 7 to 11, the solid electrolyte layer (30) comprises a solid electrolyte layer (30) disposed between the anode layer (10) and the cathode layer (20). The solid electrolyte layer (30) comprises, for example, a solid electrolyte, or a combination of a solid electrolyte and a gel electrolyte.

[0113] Solid electrolytes may include, for example, sulfide-based solid electrolytes, oxide-based solid electrolytes, polymeric solid electrolytes, or combinations thereof.

[0114] Solid electrolytes are, for example, sulfide-based solid electrolytes. Sulfide-based solid electrolytes are, for example, 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 , m, n are positive numbers, Z is one of Ge, Zn, or Ga, Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q , p, q are positive numbers, M is one of P, Si, Ge, B, Al, Ga, In, Li 7-x PS 6-x Cl x , 0(x(2, Li 7-x PS 6-x Br x , 0(x(2, and Li 7-x PS 6-x I x, 0(x(2) is one or more selected from. Sulfide-based solid electrolytes are manufactured by processing starting materials, such as Li2S or P2S5, by methods such as melt quenching or mechanical milling. Additionally, heat treatment may be performed after such processing. The solid electrolyte may be amorphous, crystalline, or a mixture thereof. Furthermore, the solid electrolyte may include sulfur (S), phosphorus (P), and lithium (Li) as at least constituent elements among the sulfide-based solid electrolyte materials described above, for example. For example, the solid electrolyte may be a material containing Li2S-P2S5. When using a sulfide-based solid electrolyte material containing Li2S-P2S5 to form the solid electrolyte, the mixed molar ratio of Li2S and P2S5 is, for example, Li2S : P2S5 = 20 : 80 to 90 : 10, 25 : 75 to 90 : 10, 30 : The range is approximately 70 to 70:30, 40:60 to 60:40.

[0115] Sulfide-based solid electrolytes may include, for example, an argyrodite-type solid electrolyte represented by the following chemical formula A:

[0116] <Chemical Formula A>

[0117] Li + 12-n-x A n+ X 2- 6-x Y - x

[0118] 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; and 1(n(5) and 0(x(2). Sulfide-based solid electrolytes are, for example, Li 7-x PS 6-x Cl x , 0≤x≤2, Li 7-xPS 6-x Br x , 0≤x≤2, and Li 7-x PS 6-x I x It may be an argyrodite-type compound containing one or more selected from 0≤x≤2. The sulfide-based solid electrolyte may be an argyrodite-type compound containing, for example, one or more selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I.

[0119] The density of the argyrodite-type solid electrolyte may be 1.5 to 2.0 g / cc. Since the argyrodite-type solid electrolyte has a density of 1.5 g / cc or higher, the internal resistance of the all-solid-state secondary battery is reduced, and penetration of the solid electrolyte layer by Li can be effectively suppressed.

[0120] Oxide-based solid electrolytes are, for example, Li 1+x+y Al x Ti 2-x Si y P 3-y O 12 (0 <x<2, 0≤y<3), BaTiO3, Pb(Zr,Ti)O3(PZT), Pb 1-x La x Zr 1-y Ti y O3(PLZT)(0≤x<1, 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(0 <x<2, 0<y<3), Li x Al y Ti z (PO4)3(0 <x<2, 0<y<1, 0<z<3), Li1+x+y (Al, Ga) x (Ti, Ge) 2-x Si y P 3-y O 12 (0≤x≤1 0≤y≤1), Li x La y TiO3(0 <x<2, 0<y<3), Li2O, LiOH, Li2CO3, LiAlO2, Li2O-Al2O3-SiO2-P2O5-TiO2-GeO2, Li 3+x La3M2O 12 (M = Te, Nb, or Zr, 0≤x≤10), or a combination thereof. Oxide-based solid electrolytes are produced, for example, by sintering.

[0121] Oxide-based solid electrolytes are, for example, Li7La3Zr2O 12 (LLZO) and Li 3+x La3Zr 2-a M a O 12 (M-doped LLZO, M=Ga, W, Nb, Ta, or Al, 0 <a<2, 0≤x≤10) 중에서 선택된 가넷계(Garnet-type) 고체전해질이다.

[0122] The polymer solid electrolyte may, for example, comprise a mixture of a lithium salt and a polymer, or comprise a polymer having ion-conducting functional groups. The polymer solid electrolyte may, for example, be a polymer electrolyte that is in a solid state at 25 °C and 1 atm. The polymer solid electrolyte may, for example, not contain a liquid.The polymeric solid electrolyte comprises a polymer, wherein the polymer is, for example, polyethylene oxide (PEO), polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene (PVDF-HFP), polyethylene oxide (PEO), poly(styrene-b-ethylene oxide) block copolymer (PS-PEO), poly(styrene-butadiene), poly(styrene-isoprene-styrene), poly(styrene-b-divinylbenzene) block copolymer, poly(styrene-ethylene oxide-styrene) block copolymer, polystyrene sulfonate (PSS), polyvinyl fluoride (PVF), poly(methylmethacrylate) (PMMA), polyethylene glycol (PEG), polyacrylonitrile (PAN), polytetrafluoroethylene (PTFE), polyethylenedioxythiophene (PEDOT), polypyrrole (PPY), polyacrylonitrile (PAN). Polyaniline, Polyacetylene, Nafion, Aquivion, Flemion, Gore, Aciplex, Morgane ADP, Sulfonated poly(ether ether ketone) (SPEEK), Sulfonated poly(arylene ether ketone ketone sulfone) (SPAEKKS), Sulfonated poly(aryl ether ketone) (SPAEK), Poly[bis(benzimidazobenzisoquinolinones)] (SPBIBI), Poly(styrene sulfonate) (PSS), Lithium 9,10-Diphenylanthracene-2-sulfonate (lithium 9,10-diphenylanthracene-2-sulfonate, DPASLi. +It may be ) or a combination thereof, but is not limited thereto, and any that are used in polymer electrolytes in the relevant technical field are permitted. Any lithium salt that can be used as a lithium salt in the relevant technical field is permitted. Examples of lithium salts include LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiCF3SO3, Li(CF3SO2)2N, LiC4F9SO3, LiAlO2, LiAlCl4, LiN(C x F 2x+1 SO2)(C y F 2y+1 The polymer may be SO2)(x and y are each 1 to 20), LiCl, LiI, or a mixture thereof. The polymer included in the polymer solid electrolyte may be, for example, a compound containing 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 may be, for example, 1,000 Dalton or more, 10,000 Dalton or more, 100,000 Dalton or more, or 1,000,000 Dalton or more.

[0123] Gel electrolytes are, for example, polymeric gel electrolytes. Gel electrolytes can have a gel state without, for example, containing polymers.

[0124] The polymer gel electrolyte may, for example, comprise a liquid electrolyte and a polymer, or comprise an organic solvent and a polymer having ion-conducting functional groups. The polymer gel electrolyte may, for example, be a polymer electrolyte in a gel state at 25 °C and 1 atm. The polymer gel electrolyte may, for example, have a gel state without containing a liquid. The liquid electrolyte used in the polymer gel electrolyte may, for example, be an ionic liquid, a mixture of a lithium salt and an organic solvent; 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. Organic solvents are, for example, propylene carbonate, ethylene carbonate, fluoroethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, methyl isopropyl carbonate, dipropyl carbonate, dibutyl carbonate, benzonitrile, acetonitrile, tetrahydrofuran, 2-methyltetrahydrofuran, γ-butyrolactone, dioxolane, 4-methyldioxolane, N,N-dimethylformamide, dimethylacetamide, dimethyl sulfoxide, dioxane, 1,2-dimethoxyethane, sulfolane, dichloroethane, chlorobenzene, nitrobenzene, diethylene glycol, dimethyl ether, or mixtures thereof. The lithium salt may be selected from lithium salts used in polymer solid electrolytes. Ionic liquids refer to salts or room-temperature molten salts that have a melting point below room temperature, are composed solely of ions, and exist in a liquid state at room temperature. Ionic liquids are, for example, a) one or more cations selected from ammonium, pyrrolidinium, pyridinium, pyrimidinium, imidazolium, piperidinium, pyrazolium, oxazolium, pyridazinium, phosphonium, sulfonium, triazolium, and mixtures thereof, and b) 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 - It may include one or more compounds selected from those containing one or more anions selected from among. The polymer solid electrolyte may form a polymer gel electrolyte by impregnating it into a liquid electrolyte in a secondary battery, for example. The polymer gel electrolyte may further include inorganic particles. The polymer included in the polymer gel electrolyte may be a compound containing, 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 Dalton or more, 1000 Dalton or more, 10,000 Dalton or more, 100,000 Dalton or more, or 1,000,000 Dalton or more.

[0125] [Solid Electrolyte Layer: Binder]

[0126] The solid electrolyte layer (30) may include, for example, a binder. The binder included in the solid electrolyte layer (30) may be, for example, styrene-butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, etc., but is not limited to these and any binder used in the relevant technical field is possible. 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.

[0127] The binder content included in the solid electrolyte layer (30) is 0.1 to 10 wt%, 0.1 to 5 wt%, 0.1 to 3 wt%, 0.1 to 1 wt%, 0 to 0.5 wt%, or 0 to 0.1 wt% based on the total weight of the solid electrolyte layer (30).

[0128] [Bipolar]

[0129] [Anode layer: Anode active material]

[0130] Referring to FIGS. 7 to 11, the positive electrode (10) comprises a positive current collector (11, 11a, 11b) and a positive active material layer (12, 12a, 12b) disposed on the positive current collector. The positive active material layer (12, 12a, 12b) comprises a positive active material.

[0131] The cathode active material is a cathode active material capable of reversibly absorbing and desorbing lithium ions. The cathode active material may be, for example, lithium transition metal oxides such as lithium cobalt oxide (LCO), lithium nickel oxide, lithium nickel cobalt oxide, lithium nickel cobalt aluminum oxide (NCA), lithium nickel cobalt manganese oxide (NCM), lithium manganate, lithium iron phosphate, or vanadium oxide, but is not necessarily limited to these; any material used as a cathode active material in the relevant technical field is acceptable. Each cathode active material may be a single material or a mixture of two or more materials.

[0132] Lithium transition metal oxides are, for example, Li a A 1-b B' b D2(wherein 0.90 ≤ a ≤ 1, and 0 ≤ b ≤ 0.5); Li a E 1-b B' b O 2-c D c (In the above formula, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05); LiE 2-b B' b O 4-c D c (In the above equation, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05); Li a Ni 1-b-c Co b B' c D α (In the above equation, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α ≤ 2); Li a Ni 1-b-c Co b B' c O 2-α F' α(In the above equation, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2); Li a Ni 1-b-c Mn b B' c D α (In the above equation, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α ≤ 2); Li a Ni 1-b-c Mn b B' c O 2-α' F' α (In the above equation, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, 0 < α < 2); Li a Ni b E c G d O2(wherein 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0.001 ≤ d ≤ 0.1); Li a Ni b Co c Mn d G e O2(wherein 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0 ≤ d ≤ 0.5, 0.001 ≤ e ≤ 0.1); Li a NiG b O2(wherein 0.90 ≤ a ≤ 1, 0.001 ≤ b ≤ 0.1); Li a CoG b O2(wherein 0.90 ≤ a ≤ 1, 0.001 ≤ b ≤ 0.1); Li a MnG b O2(wherein 0.90 ≤ a ≤ 1, 0.001 ≤ b ≤ 0.1); Li a Mn2G bO4(wherein 0.90 ≤ a ≤ 1, 0.001 ≤ b ≤ 0.1); QO2; QS2; LiQS2; V2O5; LiV2O5; LiI'O2; LiNiVO4; Li (3-f) J2(PO4)3(0 ≤ f ≤ 2); Li (3-f) Fe2(PO4)3(0 ≤ f ≤ 2); a compound represented by any one of the chemical formulas of LiFePO4. In such a 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; Q is Ti, Mo, Mn, 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. A compound having a coating layer added to the surface of such a compound may also be used, and a mixture of the compound described above and a compound having a coating layer added may also be used. The coating layer applied to the surface of such a compound comprises, for example, a coating element compound of an oxide, hydroxide, oxyhydroxide, oxycarbonate, or hydroxycarbonate of a coating element. The compound forming this coating layer is amorphous or crystalline. The coating elements included in the coating layer are Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or mixtures thereof. The method for forming the coating layer is selected within a range that does not adversely affect the physical properties of the cathode active material. The coating method is, for example, spray coating or immersion. Since specific coating methods are well understood by those skilled in the art, a detailed explanation will be omitted.

[0133] The cathode active material may include, for example, a lithium transition metal oxide represented by the following chemical formulas 1 to 8:

[0134] <Chemical Formula 1>

[0135] Li a Ni x Co y M z O 2-b A b

[0136] In the above chemical formula 1,

[0137] 1.0≤a≤1.2, 0≤b≤0.2, 0.8≤x<1, 0≤y≤0.3, 0 <z≤0.3, 및 x+y+z=1이고,

[0138] 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,

[0139] A is F, S, Cl, Br, or a combination thereof, and

[0140] <Chemical Formula 2>

[0141] LiNi x Co y Mn z O2

[0142] <Chemical Formula 3>

[0143] LiNi x Co y Al z O2

[0144] In the above chemical formulas 2 to 3, 0.8≤x≤0.95, 0≤y≤0.2, 0 <z≤0.2 및 x+y+z=1이며,

[0145] <Chemical Formula 4>

[0146] LiNi x Co y Mn z Al w O2

[0147] In the above chemical formula 4, 0.8≤x≤0.95, 0≤y≤0.2, 0 <z≤0.2, 0<w≤0.2, 및 x+y+z+w=1이며,

[0148] <Chemical Formula 5>

[0149] Li a Co x M y O 2-b A b

[0150] In the above chemical formula 5,

[0151] 1.0≤a≤1.2, 0≤b≤0.2, 0.9≤x≤1, 0≤y≤0.1, and x+y=1, and

[0152] 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,

[0153] A is F, S, Cl, Br, or a combination thereof, and

[0154] <Chemical Formula 6>

[0155] Li a Ni x Mn y M' z O 2-b A b

[0156] In the above chemical formula 6,

[0157] 1.0≤a≤1.2, 0≤b≤0.2, 0 <x≤0.3, 0.5≤y<1, 0<z≤0.3, 및 x+y+z=1이고,

[0158] 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

[0159] A is F, S, Cl, Br, or a combination thereof, and

[0160] <Chemical Formula 7>

[0161] Li a M1 x M2 y PO 4-b X b

[0162] In the above chemical formula 7, 0.90≤a≤1.1, 0≤x≤0.9, 0≤y≤0.5, 0.9 <x+y<1.1, 0≤b≤2 이며,

[0163] M1 is chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zirconium (Zr), or a combination thereof, and

[0164] 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.

[0165] <Chemical Formula 8>

[0166] Li a M3 z PO4

[0167] In the above chemical formula 8, 0.90≤a≤1.1 and 0.9≤z≤1.1, and

[0168] M3 is chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zirconium (Zr), or a combination thereof.

[0169] The oxide-based cathode active material may be covered by a coating layer. The coating layer may be any material known as a coating layer for the cathode active material of an all-solid-state secondary battery. For example, the coating layer is Li2O-ZrO2(LZO), etc.

[0170] The size of the oxide-based cathode active material may be, for example, 0.1 to 30 μm, 0.5 to 20 μm, or 1 to 15 μm. The oxide-based cathode active material may be, for example, single-crystal particles or polycrystalline particles.

[0171] The shape of the positive active material is, for example, a particle shape such as a sphere, an elliptical sphere, etc. The particle size of the positive active material is not particularly limited and is within a range applicable to the positive active material of a conventional all-solid-state secondary battery. The content of the positive active material of the positive layer (10) is also not particularly limited and is within a range applicable to the positive layer of a conventional all-solid-state secondary battery. The content of the positive active material included in the positive active material layer (12, 12a, 12b) may be 80 to 99 weight%, 80 to 95 weight%, or 80 to 90 weight% of the total weight of the positive active material layer (12, 12a, 12b).

[0172] [Anode layer: Solid electrolyte]

[0173] 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 the same as or different from the solid electrolyte included in the solid electrolyte layer (30). For details regarding the solid electrolyte, refer to the solid electrolyte layer (30).

[0174] The solid electrolyte included in the positive electrode active material layer (12) may have a smaller D50 average particle size compared to 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 diameter (D50). The median particle diameter (D50) is the particle size corresponding to 50% of the cumulative volume calculated from the side of the particle having a small particle size in the particle size distribution measured, for example, by laser diffraction.

[0175] The solid electrolyte content included in the positive electrode active material layer (12) may be, for example, 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).

[0176] [Bipolar Layer: Challenge Material]

[0177] 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, carbon black, acetylene black, Ketjen black, carbon fiber, or a combination thereof, but is not limited to these, and any material used as a carbon-based conductive material in the relevant technical field is possible. The metal-based conductive material may be metal powder, metal fiber, or a combination thereof, but is not limited to these, and any material used as a metal-based conductive material in the relevant technical field is possible. The content of the conductive material included in the positive electrode active material layer (12) may be, for example, 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).

[0178] [Bipolar layer: Binder]

[0179] The positive active material layer (12) may further include a binder. The binder may be, for example, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, etc., but is not limited to these and any binder used in the relevant technical field may be used. The binder content included in the positive active material layer (12) may be, for example, 1 wt% to 10 wt% of the total weight of the positive active material layer (12). The binder may be omitted.

[0180] [Anode Layer: Other Additives]

[0181] The positive active material layer (12) may further include additives such as fillers, coating agents, dispersants, and ion conductivity aids in addition to the positive active material, solid electrolyte, binder, and conductive material described above.

[0182] The filler, coating agent, dispersant, ion-conducting auxiliary agent, etc. that the positive active material layer (12) may include can be any known material generally used in the electrodes of all-solid-state secondary batteries.

[0183] [Bipolar layer: Bipolar current collector]

[0184] The positive current collector (11) is 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, such as a plate or foil. The positive current collector (11) may be omitted. The thickness of the positive current collector (11) is, for example, 1 μm to 100 μm, 1 μm to 50 μm, 5 μm to 25 μm, or 10 μm to 20 μm.

[0185] The positive current collector (11) 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 be, for example, a thermoplastic polymer. The polymer may include, for example, polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polybutylene terephthalate (PBT), polyimide (PI), or a combination thereof. The base film may be, for example, an insulator. By including an insulating thermoplastic polymer in the base film, the base film may soften or liquefy upon a short circuit, thereby blocking battery operation and suppressing a sudden increase in current. 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), or an alloy thereof. The metal layer can act as an electrochemical fuse and be cut off upon overcurrent to perform a short-circuit prevention function. The limit current and maximum current can be controlled by adjusting the thickness of the metal layer. The metal layer can be plated or deposited on the base film. As the thickness of the metal layer decreases, the limit current and / or maximum current of the positive current collector (11) decreases, thereby improving the stability of the lithium battery during a short circuit. A lead tab may be added to the metal layer for external connection. The lead tab may be welded to the metal layer or the metal layer / base film laminate by ultrasonic welding, laser welding, spot welding, etc. During welding, the base film and / or metal layer melt, allowing the metal layer to be electrically connected to the lead tab. To make the weld between the metal layer and the lead tab more robust, a metal chip may be added between the metal layer and the lead tab.The metal chip may be a thin sheet of the same material as the metal of the metal layer. The metal chip may be, for example, a metal foil, a metal mesh, etc. The metal chip may be, for example, an aluminum foil, a copper foil, a SUS foil, etc. A lead tab may be welded to a metal chip / metal layer laminate or a metal chip / metal layer / base film laminate by placing the metal chip on the metal layer and then welding it to the lead tab. During welding, the base film, the metal layer, and / or the metal chip may melt, thereby electrically connecting the metal layer or the metal layer / metal chip laminate to the lead tab. A metal chip and / or lead tab may be added to a portion of the metal layer. The thickness of the base film may be, for example, 1 to 50 μm, 1.5 to 50 μm, 1.5 to 40 μm, or 1 to 30 μm. By having the base film within this range of thickness, the weight of the electrode assembly can be reduced more effectively. The melting point of the base film may be, for example, 100 to 300 °C, 100 to 250 °C or lower, or 100 to 200 °C. Since the base film has a melting point within this range, the base film can melt during the welding process of the lead tab and be easily bonded to the lead tab. Surface treatments, such as corona treatment, may be performed on the base film to improve the adhesion between the base film and the metal layer. The thickness of the metal layer may be, for example, 0.01 to 3 μm, 0.1 to 3 μm, 0.1 to 2 μm, or 0.1 to μm. Since the metal layer has a thickness within this range, the stability of the electrode assembly can be ensured while maintaining conductivity. The thickness of the metal piece may be, for example, 2 to 10 μm, 2 to 7 μm, or 4 to 6 μm. Since the metal piece has a thickness within this range, the connection between the metal layer and the lead tab can be performed more easily. By having the positive current collector (11) have this structure, the weight of the positive electrode can be reduced and, as a result, the energy density of the positive electrode and the all-solid-state secondary battery can be improved.

[0186] [Bipolar layer: Inert component]

[0187] Referring to FIGS. 9 to 11, the anode (10) includes an anode current collector (11) and an anode active material layer (12) disposed on one side of the anode current collector. An inactive member (40) is disposed on one side of the anode layer (10).

[0188] By including an inert member (40), cracking of the solid electrolyte layer (30) is prevented during manufacturing and / or charging and discharging of the all-solid-state secondary battery (1), and consequently, the cycle characteristics of the all-solid-state secondary battery (2) are improved. In an all-solid-state secondary battery (1) that does not include an inert member (40), uneven pressure is applied to the solid electrolyte layer (30) in contact with the positive electrode (10) during manufacturing and / or charging and discharging of the all-solid-state secondary battery (1), causing cracking in the solid electrolyte layer (30), and the likelihood of a short circuit occurring due to the growth of lithium metal through this increases. The inert member (40) surrounds part or all of the side of the positive electrode (10) and contacts the solid electrolyte layer (30). By having the inert member (40) surround the side of the anode (10) and come into contact with the solid electrolyte layer (30), cracks in the solid electrolyte layer (30) caused by pressure differences during the pressing process in the solid electrolyte layer (30) that does not come into contact with the anode (20) can be effectively suppressed. The inert member (40) surrounds the side of the anode (10) and is separated from the cathode (20), more specifically from the first cathode active material layer (22). The inert member (40) surrounds the side of the anode (10), comes into contact with the solid electrolyte layer (30), and is separated from the cathode (20). Therefore, the possibility of a short circuit occurring due to physical contact between the anode (10) and the first cathode active material layer (22), or due to overcharging of lithium, is suppressed.

[0189] Referring to FIG. 9, an inert member (40) is disposed on one side of the positive active material layer (12) and the positive current collector (11). By simultaneously disposing of the inert member (40) on one side of the positive active material layer (12) and the positive current collector (11), the possibility of a short circuit occurring due to contact between the positive current collector (11) and the negative electrode (20) can be suppressed more effectively. Referring to FIG. 10, the inert member (40) is disposed on one side of the positive active material layer (12) and is disposed between the solid electrolyte layer (40) and the positive current collector (11) facing the solid electrolyte layer (40). The inert member (40) is not disposed on one side of the positive current collector (11). By disposing of the inert member (40) between the positive current collector (11) and the solid electrolyte layer (40), a short circuit caused by contact between the positive current collector (11) and the negative electrode (20) can be effectively prevented.

[0190] Referring to FIGS. 9 to 11, the inert member (40) extends from one side of the anode (30) to the end portion of the solid electrolyte layer (30). By extending the inert member (40) to the end portion of the solid electrolyte layer (30), cracks occurring at the end portion of the solid electrolyte layer (30) can be suppressed. The end portion of the solid electrolyte layer (30) is the outermost portion that contacts the side of the solid electrolyte layer (30). The inert member (40) extends to the outermost portion that contacts the side of the solid electrolyte layer (30). The inert member (40) is separated from the cathode layer (20), more specifically from the first cathode active material layer (22). The inert member (40) extends to the end portion of the solid electrolyte layer (30) but does not come into contact with the cathode layer (20). The inert member (40) fills a space extending, for example, from one side of the anode layer (30) to the end of the solid electrolyte layer (30).

[0191] The inert member (40) may be, for example, a gasket. By using a gasket as the inert member (40), cracks in the solid electrolyte layer (30) caused by pressure differences during the pressurization process can be effectively suppressed.

[0192] The inert member (40) has, for example, a single-layer structure. Alternatively, although not shown in the drawings, the inert member (40) may have a multi-layer structure. In the inert member (40) having a multi-layer structure, each layer may have a different composition. The inert member 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 inert member (40) having a multi-layer structure may include, for example, one or more adhesive layers and one or more support layers. The adhesive layer effectively prevents separation between the anode layer (10) and the solid electrolyte layer (30) caused by volume changes of the anode layer (10) during the charging and discharging process of the all-solid-state secondary battery (10), for example, and improves the film strength of the inert member (40) by providing bonding force between the support layer and other layers. The support layer provides support to the first inert member (40), prevents non-uniformity of pressure applied to the solid electrolyte layer (30) during the pressurization process or the charging / discharging process, and prevents deformation of the shape of the all-solid-state secondary battery (1) being manufactured.

[0193] Referring to FIG. 11, the all-solid-state secondary battery (1) comprises a positive electrode (10), a negative electrode (20), and a solid electrolyte layer (30) disposed between them. The positive electrode layer (10) comprises a positive current collector (11) and a first positive active material layer (12a) and a second positive active material layer (12b) disposed on both sides of the positive current collector (11). The solid electrolyte layer (30) comprises a first solid electrolyte layer (30a) in contact with the first positive active material layer (12a) and a second solid electrolyte layer (30b) in contact with the second positive active material layer (12b). The negative electrode layer (20) comprises 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). An inert member (40) is arranged to surround the side of the anode layer (10) between the first solid electrolyte layer (30a) and the second solid electrolyte layer (30b) facing each other. The inert member (40) includes, for example, a first inert member (40a) in contact with the first solid electrolyte layer (30a) and a second inert member (40b) in contact with the second solid electrolyte layer (30b). Thus, the all-solid-state secondary battery (1) has a bi-cell structure. Since the all-solid-state secondary battery (1) has such a bi-cell structure, the solid electrolyte layer (30) and the negative electrode layer (20) are arranged symmetrically facing each other with the anode layer (10) as the center, so structural deformation caused by pressure applied during the manufacturing of the all-solid-state secondary battery (1) is more effectively suppressed. Accordingly, cracking of the solid electrolyte layer (30) is suppressed during the manufacturing process and / or charging and discharging process of the all-solid-state secondary battery (1), thereby preventing short circuits of the all-solid-state secondary battery (1) and consequently further improving the cycle characteristics of the all-solid-state secondary battery (1). In addition, since only one positive current collector (11) is used for a plurality of positive active material layers (12a, 12b), the energy density of the all-solid-state secondary battery (1) can be increased.

[0194] The present invention is explained in more detail through the following examples and comparative examples. However, the examples are intended to illustrate the present invention and do not limit the scope of the present invention.

[0195] (Manufacturing of all-solid-state secondary batteries, full cell)

[0196] Example 1

[0197] (Anode layer manufacturing)

[0198] LiNi coated with Li2O-ZrO2 (LZO) as a cathode active material 0.8 Co 0.15 Mn 0.05 O2 (NCM) was prepared. The LZO-coated cathode active material was prepared according to the method disclosed in Korean Patent Publication No. 10-2016-0064942. As a solid electrolyte, Li6PS5Cl, an argyrodite-type crystal (D50 = 0.5 μm, crystalline), was prepared. As a binder, a polytetrafluoroethylene (PTFE) binder was prepared. As a conductive agent, carbon nanofibers (CNF) were prepared. A slurry was prepared by mixing these materials with a xylene solvent in a weight ratio of cathode active material: solid electrolyte: conductive agent: binder = 84: 11.5: 3: 1.5, molding the mixture into a sheet shape, and then vacuum drying it at 40°C for 8 hours to produce a cathode sheet. The prepared cathode sheet was placed on the carbon layer of a cathode current collector made of aluminum foil coated with a carbon layer on one side, and 85 o The anode layer was manufactured by a heated roll press of C. The total thickness of the anode layer was approximately 120 μm. The thickness of the anode active material layer was approximately 95 μm, and the thickness of the carbon-coated aluminum foil was approximately 25 μm.

[0199] (Preparation of solid electrolyte layer)

[0200] A mixture was prepared by adding 1 part by weight of styrene-butadiene rubber (SBR) binder to 100 parts by weight of a crystalline Li6PS5Cl solid electrolyte with an average particle size of 3 μm. A slurry was prepared by stirring while adding xylene and diethylbenzene to the prepared mixture. The prepared slurry was applied onto a nonwoven fabric using a blade coater and dried in air at a temperature of 40 °C to obtain a laminate. The obtained laminate was vacuum dried at 40 °C for 12 hours. A solid electrolyte layer was prepared by the above process.

[0201] (Cathode layer manufacturing)

[0202] A SUS foil with a thickness of 10 μm was prepared as a negative electrode current collector. As the first negative electrode active material, LTO (Li4Ti5O) with an average particle size of 1 μm was prepared. 12 ) particles were prepared. As a second cathode active material, a 3:1 weight ratio mixture of carbon black (CB) with a primary particle size of about 30 nm and silver (Ag) particles with an average particle diameter of about 60 nm was prepared.

[0203] 0.04 g of the first cathode active material and 3.96 g of a mixture of the second cathode active material were placed in a container, and 4 g of an NMP solution containing 7 wt% of a PVDF binder (Kureha #9300) was added to prepare a mixed solution. Subsequently, a slurry was prepared by stirring the mixed solution while gradually adding NMP to it. The prepared slurry was applied onto the carbon layer of the prepared cathode current collector using a bar coater and dried in air at 80°C for 10 minutes. The resulting laminate was vacuum dried at 40°C for 10 hours. The dried laminate was cold-roll-pressed to flatten the surface of the first cathode active material layer of the laminate. The cathode layer was fabricated by the above process. The thickness of the first cathode active material layer contained in the cathode layer was approximately 5 μm.

[0204] (Manufacturing of all-solid-state secondary batteries)

[0205] A laminate was prepared by placing a solid electrolyte layer on the positive active material layer of the positive layer at the bottom of a container, and placing a negative electrode layer on the solid electrolyte layer such that the negative active material layer contacts the solid electrolyte layer. A torque cell was prepared by applying pressure to the prepared laminate while rotating the lid of the container. Through this pressure treatment, the solid electrolyte layer is sintered, thereby improving battery characteristics.

[0206] Example 2

[0207] An all-solid-state secondary battery was manufactured in the same manner as in Example 1, except that 0.04 g of the first negative electrode active material and 3.96 g of the second negative electrode active material were changed to 0.02 g of the first negative electrode active material and 3.98 g of the second negative electrode active material.

[0208] Example 3

[0209] An all-solid-state secondary battery was manufactured in the same manner as in Example 1, except that 0.04 g of the first negative electrode active material and 3.96 g of the second negative electrode active material were changed to 0.01 g of the first negative electrode active material and 3.99 g of the second negative electrode active material.

[0210] Comparative Example 1

[0211] An all-solid-state secondary battery was manufactured in the same manner as in Example 1, except that 0.04 g of the first negative electrode active material and 3.96 g of the second negative electrode active material were changed to 0 g of the first negative electrode active material and 4 g of the second negative electrode active material.

[0212] Reference Example 1

[0213] An all-solid-state secondary battery was manufactured in the same manner as in Example 1, except that 0.04 g of the first negative electrode active material and 3.96 g of the second negative electrode active material were changed to 4 g of the first negative electrode active material and 0 g of the second negative electrode active material.

[0214] (Manufacturing of all-solid-state secondary batteries, half cell)

[0215] Examples 4 to 6

[0216] An all-solid-state secondary battery was manufactured using the same method as in Example 1, except that a half cell was manufactured using a lithium metal electrode as the counter electrode instead of the positive electrode.

[0217] Comparative Example 2

[0218] An all-solid-state secondary battery was manufactured using the same method as Comparative Example 1, except that a half cell was manufactured using a lithium metal electrode as the counter electrode instead of the positive electrode.

[0219] Reference Example 2

[0220] An all-solid-state secondary battery was manufactured using the same method as Reference Example 1, except that a half cell was manufactured using a lithium metal electrode as the counter electrode instead of the positive electrode.

[0221]

[0222] Evaluation Example 1: SEM Analysis

[0223] Scanning electron microscope images of a simple mixture (1:99 weight ratio mixture) of the first cathode active material and the second cathode active material prepared in Example 1 are shown in Figure 1.

[0224] In Figure 1, the particles shown in black are LTO particles, which are the first cathode active material, and the particles shown in white are Ag particles, which are the second cathode active material.

[0225]

[0226] Evaluation Example 2: Impedance Analysis

[0227] For the half-cells prepared in Example 4 and Comparative Example 2, 0.3 mA / cm at 45 ℃ 3 It was charged at a current density until it reached about 0 V (vs. Li+ / Li).

[0228] The impedance of the pellet was measured for the charged half-cell using the 2-probe method with an impedance analyzer (Solartron 1400A / 1455A impedance analyzer). The frequency range was 0.1 Hz to 1 MHz, and the amplitude voltage was 10 mV. Measurements were performed at 25°C in an air atmosphere. The Nyquist plot for the impedance measurement results is shown in Fig. 2. From the Nyquist plot, the charge transfer resistance (R ct The Charge Transfer Resistance was calculated, and the results are shown in Table 1 below.

[0229] R ct [Ω] Example 4 (LTO 1 wt%) 3.0 Comparative Example 2 (LTO 0 wt%) 4.0

[0230] As shown in Figure 2 and Table 1, the electron transfer resistance of the half-cell of Example 4 was reduced by about 25% compared to the half-cell of Comparative Example 2. It was confirmed that the transfer of lithium ions at the interface between the solid electrolyte layer and the first negative electrode active material layer in the half-cell of Example 4 was performed more easily than in the half-cell of Comparative Example 2.

[0231]

[0232] Evaluation Example 3: Measurement of lithiation potential

[0233] For the half-cells prepared in Examples 4 to 6, Comparative Example 2, and Reference Example 2, 0.3 mA / cm² at 45 °C 3 It was charged at a current density until it reached about 0 V (vs. Li+ / Li).

[0234] A profile of the rate of change of capacity (dQ / dV) according to the voltage (V) during charging was plotted, and the lithiation potential was measured from the voltage position where a peak appears in the profile.

[0235] Some of the measurement results are shown in Figure 3 and Table 2.

[0236] Figure 3 is a profile of the rate of change of capacity (dQ / dV) according to voltage (V) for half cells manufactured in Comparative Example 2 and Reference Example 2.

[0237] As shown in Fig. 3, the half-cell of Reference Example 2 containing only LTO as the first cathode active material showed a peak indicating a lithiation potential at about 1.55 V (vs. Li+ / Li).

[0238] In contrast, the half-cell of Comparative Example 2, which contains only Ag and amorphous carbon as the second negative electrode active material, showed a peak indicating a lithiation potential at about 0.040 V (vs. Li+ / Li).

[0239] Therefore, it was confirmed that the lithiation potential of the Hass cell of Reference Example 2 containing LTO was 1.4 V higher than that of the half cell of Comparative Example 2 containing Ag and amorphous carbon.

[0240] Lithium potential [V vs. Li + / Li]Example 4 (LTO 1 wt%) 0.046 Example 5 (LTO 0.5 wt%) 0.048 Example 6 (LTO 0.25 wt%) 0.044 Comparative Example 2 (LTO 0 wt%) 0.040

[0241] As shown in Table 2, the half-cells of Examples 4 to 6 showed an increased lithiation potential compared to the half-cell of Comparative Example 2. Therefore, in the first negative electrode active material layer of the half-cells of Examples 4 to 6, the first negative electrode active material (LTO) is lithiated before the second negative electrode active material (Ag and amorphous carbon), thereby additionally forming an ion conduction path within the first negative electrode active material layer. Consequently, the overall lithium ion conductivity of the first negative electrode active material layer can be improved. As a result, the uniformity of the lithium precipitation reaction in the half-cell can be improved.

[0242]

[0243] Evaluation Example 4: Overpotential Measurement

[0244] For the half-cells prepared in Examples 4 to 6 and Comparative Example 2, 0.3 mA / cm at 45 ℃ 3 With a current density, the capacity is approximately 6 mAh / cm² 2 Charged until reached.

[0245] The charging profile of the half-cell is shown in Fig. 4. The lithium nucleation overpotential was measured from the charging profile of Fig. 4, and the results are shown in Table 3.

[0246] Lithium nucleation overpotential [mV vs. Li + / Li] Example 4 (LTO 1 wt%) 20 Example 5 (LTO 0.5 wt%) 25 Example 6 (LTO 0.25 wt%) 15 Comparative Example 2 (LTO 0 wt%) 33

[0247] As shown in Table 3, the lithium nucleation overpotential in the half-cells of Examples 4 to 6 was reduced compared to the half-cell of Comparative Example 2. Since stable deposition of lithium is possible in the half-cells of Examples 4 to 6, the growth of lithium dendrites can be suppressed and the side reactions of lithium can be suppressed more effectively compared to the half-cell of Comparative Example 2.

[0248]

[0249] Evaluation Example 5: Measurement of Lithium Ion Diffusivity

[0250] The lithium ion diffusivity of the half-cells prepared in Example 4 and Comparative Example 2 was measured through GITT (Galvanostatic Intermittent Titration Technique) analysis.

[0251] The GITT measurement conditions are as follows: 0.3 mA / cm² at 45 ℃ for the fabricated half-cell 3 5-minute charge at current density, 2-hour rest time, 0.3 mA / cm² 3A cycle of 5 minutes of charging and 2 hours of rest time was repeated at a current density. The above cycle was repeated until the voltage of the half-cell reached 0 V (vs. Li+ / Li).

[0252] The measurement results are shown in Figures 5a to 5c and Table 4 below.

[0253] Figure 5a is a profile showing the voltage change according to capacitance caused by constant current pulses applied intermittently during the GITT measurement process.

[0254] Figure 5b is an enlarged view of a portion (boxed portion) of Figure 5a. Figure 5c is a profile showing the voltage change over time due to an applied constant current pulse, which is the result of the GITT measurement of Figure 5a.

[0255] ΔEs is the steady-state voltage change and ΔEt is the voltage change while a constant current pulse is applied.

[0256] ΔEs / ΔEt Example 4 (LTO 1 wt%) 0.9 Comparative Example 2 (LTO 0 wt%) 0.7

[0257] As shown in Table 4, the ΔEs / ΔEt value in the half-cell of Example 4 increased compared to the half-cell of Comparative Example 2. ΔEs / ΔEt has a relationship proportional to lithium ion diffusivity. The lithium ion diffusivity in the half-cell of Example 4 increased compared to the half-cell of Comparative Example 2.

[0258] Compared to the half cell of Comparative Example 2, lithium ions diffuse and / or move more easily in the half cell of Example 4, so side reactions between the solid electrolyte and lithium caused by the formation of lithium metal at the interface between the solid electrolyte and the first negative electrode active material layer can be suppressed more effectively.

[0259]

[0260] Evaluation Example 6: Evaluation of High Rate Characteristics at High Temperature (45℃)

[0261] The all-solid-state secondary battery (full cell) prepared in Example 1 and Comparative Example 1 was charged at a constant current rate of 0.05 C at 45°C until the voltage reached 4.25 V (vs. Li). Subsequently, it was discharged at a constant current rate of 0.05 C until the voltage reached 2.5 V (vs. Li) during discharge. The above cycle was repeated twice (Cycle 1 to Cycle 2).

[0262] 2 nd The lithium battery that had undergone cycling was charged at a constant current rate of 0.1 C at 45°C until the voltage reached 4.25 V (vs. Li). Subsequently, it was discharged at a constant current rate of 0.1 C until the voltage reached 2.5 V (vs. Li) during discharge. The above cycle was repeated three times (3rd to 5th cycles).

[0263] 5 th The lithium battery that had undergone cycling was charged at a constant current rate of 0.1 C at 45°C until the voltage reached 4.25 V (vs. Li). Subsequently, it was discharged at a constant current rate of 0.2 C until the voltage reached 2.5 V (vs. Li) during discharge. The above cycle was repeated three times (6th to 8th cycles).

[0264] 8 th The lithium battery that had undergone cycling was charged at a constant current rate of 0.1 C at 45°C until the voltage reached 4.25 V (vs. Li). Subsequently, it was discharged at a constant current rate of 0.3 C until the voltage reached 2.5 V (vs. Li) during discharge. The above cycle was repeated three times (9th to 11th cycles).

[0265] 11 thThe lithium battery that had undergone cycling was charged at a constant current rate of 0.1 C at 45°C until the voltage reached 4.25 V (vs. Li). Subsequently, it was discharged at a constant current rate of 0.5 C until the voltage reached 2.5 V (vs. Li) during discharge. The above cycle was repeated three times (12th to 14th cycles).

[0266] 14 th The lithium battery that had undergone cycling was charged at a constant current rate of 0.1 C at 45°C until the voltage reached 4.25 V (vs. Li). Subsequently, it was discharged at a constant current rate of 1 C until the voltage reached 2.5 V (vs. Li) during discharge. The above cycle was repeated 3 times (cycles 15 to 17).

[0267] In all charge / discharge cycles, a 10-minute pause was taken after each charge / discharge cycle. The results of the high-rate discharge characteristics are shown in Figure 6 and Table 5 below. The high-rate characteristic is defined by the following Equation 5. The high-rate characteristic is the average value of multiple cycles performed under the same discharge conditions.

[0268] <Mathematical Formula 5>

[0269] High Rate Characteristic [%] = [Discharge Capacity at n C rate / Discharge Capacity at 0.05 C rate] × 100

[0270] In the above formula, n is 0.1, 0.2, 0.3, 0.5, or 1.

[0271] 0.5C[%] 1.0C[%] Example 1 (LTO 1 wt%) 79.17 1.1 Comparative Example 1 (LTO 0 wt%) 63.65 5.6

[0272] As shown in Figure 6 and Table 5, the all-solid-state secondary battery of Example 1 containing the first negative electrode active material showed improved high-rate characteristics compared to the all-solid-state secondary battery of Comparative Example 1 that does not contain the first negative electrode active material.

[0273] According to the new all-solid-state secondary battery, it is possible to provide an all-solid-state secondary battery with improved cycle characteristics, particularly high-rate characteristics, by improving the uniformity of the lithium precipitation reaction and suppressing the precipitation of lithium dendrites.

Claims

1. A positive electrode layer; a negative electrode layer; and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer, comprising The above anode layer includes an anode active material layer, The above cathode layer comprises a cathode current collector; and a first cathode active material layer disposed between the cathode current collector and the solid electrolyte layer, and The above first negative electrode active material layer comprises a first negative electrode active material and a second negative electrode active material, and The first negative electrode active material comprises a lithium metal oxide, a metal oxide, or a combination thereof, and A solid-state secondary battery in which the second negative electrode active material comprises a metal-based negative electrode active material, a carbon-based negative electrode active material, or a combination thereof.

2. In Paragraph 1, All-solid-state secondary battery comprising the above lithium metal oxide and metal oxide independently of each other, metals belonging to groups 2 to 14 of the periodic table.

3. In Paragraph 1, All-solid-state secondary battery in which the lithium metal oxide and the metal oxide independently comprise titanium, zirconium, manganese, molybdenum, vanadium, magnesium, silicon, iron, zinc, tin, nickel, or a combination thereof.

4. In Paragraph 1, The above lithium metal oxide is Li 4+x Ti5O 12+y (-1≤x≤3, -0.5≤y≤0.5), Li x Fe3O4(0≤x≤2), Li x Includes TiO2 (0≤x≤1) or a combination thereof, The above metal oxides are TiO2, ZrO2, MnO2, MoO2, V2O5, MgO, SiO2, SiO x (0 <x<2), Fe3O4, ZnO, SnO2, NiO 또는 이들의 조합을 포함하는, 전고체 이차전지.

5. In Paragraph 1, The first lithiation potential of the first negative electrode active material is higher than the second lithiation potential of the second negative electrode active material, and A solid-state secondary battery in which the first and second lithium potentials are determined by the position of a peak from the profile of the capacity change rate (dQ / dV) according to the voltage (V) during the initial charging of the solid-state secondary battery.

6. In Paragraph 1, An all-solid-state secondary battery in which the difference between the first lithiation potential of the first metal oxide and the second lithiation potential of the second negative electrode active material is 0.4 V or more.

7. In Paragraph 1, The first lithiation potential of the first negative electrode active material is 1 V (vs. Li + / Li) is more than, The second lithiation potential of the above second negative electrode active material is 0.5 V (vs. Li + All-solid-state secondary battery with less than / Li.

8. In Paragraph 1, All-solid-state secondary battery, wherein the content of the first negative electrode active material is 0.1 to 5 wt% with respect to the total weight of the first negative electrode active material and the second negative electrode active material.

9. In Paragraph 1, The first negative electrode active material is in the form of particles, the particle size of the first negative electrode active material is 5 μm or less, and the aspect ratio of the first negative electrode active material is 5 or less, and The second negative electrode active material is in the form of particles, the particle size of the second negative electrode active material is less than 1 μm, and the aspect ratio of the second negative electrode active material is 5 or less, and A solid-state secondary battery in which the particle size of the second negative electrode active material is smaller than the particle size of the first negative electrode active material.

10. In Paragraph 1, The above-mentioned metal-based negative electrode active material includes a metal capable of forming an alloy or compound with lithium, and An all-solid-state secondary battery comprising a metal capable of forming an alloy or compound with the lithium, wherein the metal comprises zinc (Zn), gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), iridium (Ir), osmium (Os), rhodium (Rh), ruthenium (Ru), or a combination thereof.

11. In Paragraph 1, An all-solid-state secondary battery in which the carbon-based negative electrode active material comprises amorphous carbon, crystalline carbon, porous carbon, or a combination thereof.

12. In Paragraph 1, The above second negative electrode active material comprises a mixture of first particles made of amorphous carbon and second particles made of a metal-based negative electrode active material, and A solid-state secondary battery in which the content of the second particle is 1 to 60 wt% based on the total weight of the mixture of the first particle and the second particle.

13. In Paragraph 1, The above first negative electrode active material layer further includes a binder, The above binder includes a polymer binder, and the above polymer binder includes a fluorine-based binder, An all-solid-state secondary battery in which the content of the binder is 0.1 to 20 parts by weight per 100 parts by weight of the mixture of the first negative electrode active material and the second negative electrode active material.

14. In Paragraph 1, The thickness of the first negative electrode active material layer is 50% or less of the thickness of the positive electrode active material layer, and All-solid-state secondary battery having a thickness of 1 to 50 μm of the first negative electrode active material layer.

15. In Paragraph 1, All-solid-state secondary battery, wherein the ratio (B / A) of the initial charge capacity (B) of the first negative electrode active material layer and the initial charge capacity (A) of the positive electrode active material layer is 0.001 to 0.

45.

16. In Paragraph 1, It further includes a second negative active material layer disposed between the negative current collector and the first negative active material layer or between the negative current collector and the electrolyte layer, The above-mentioned second negative electrode active material layer is a metal layer, and the metal layer comprises lithium or a lithium alloy, in an all-solid-state secondary battery.

17. In Paragraph 1, An all-solid-state secondary battery in which the above-mentioned solid electrolyte layer comprises a sulfide-based solid electrolyte, an oxide-based solid electrolyte, a polymer solid electrolyte, or a combination thereof.

18. In Paragraph 17, The above sulfide-based solid electrolyte is Li2S-P2S5, Li2S-P2S5-LiX (X = Cl, Br, F, or I), Li2S-P2S5-LiCl-LiBr, 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 , m, n are positive numbers, Z is one of Ge, Zn, or Ga, Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q , p, q are positive numbers, M is one of P, Si, Ge, B, Al, Ga, In, Li 7-x PS 6-x Cl x , 0≤x≤2, Li 7-x PS 6-x Br x , 0≤x≤2, and Li 7-x PS 6-x I x Includes one or more selected from , 0≤x≤2, and The above sulfide-based solid electrolyte includes an argyrodite-type solid electrolyte, and The above argyrodite-type solid electrolyte comprises one or more selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I, and All-solid-state secondary battery having a density of 1.5 to 2.0 g / cc of the argyrodite-type solid electrolyte.

19. In Paragraph 1, The above positive active material layer further comprises one or more selected from a solid electrolyte, a conductive material, and a binder, and All-solid-state secondary battery, wherein the above-mentioned solid electrolyte comprises a sulfide-based solid electrolyte.

20. In Paragraph 1, One or more of the above positive current collector and negative current collector comprises a base film and a metal layer disposed on one or both sides of the base film, and The above base film comprises a polymer, wherein the polymer comprises polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polybutylene terephthalate (PBT), polyimide (PI), or a combination thereof, All-solid-state secondary battery, wherein the metal layer comprises indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), or an alloy thereof.

Images