All-solid-state secondary batteries

Abstract

To provide an all-solid secondary battery.SOLUTION: An all-solid secondary battery 1 includes a positive electrode layer 10, a negative electrode layer 20, and a solid electrolyte layer 30 disposed between the positive electrode layer 10 and the negative electrode layer 20. The positive electrode layer 10 includes a positive electrode current collector 11 and a positive electrode active material layer 12 disposed on one surface or both surfaces of the positive electrode current collector. The positive electrode active material layer 12 includes a lithium-containing sulfide-based positive electrode active material. The lithium-containing sulfide-based positive electrode active material includes Li2S, a Li2S-containing composite, or a combination thereof. The all-solid secondary battery includes a first inactive member 40 disposed on one side surface of the positive electrode layer 10. The negative electrode layer 20 includes a negative electrode current collector 21 and a first negative electrode active material layer 22 disposed on one surface of the negative electrode current collector 21. A ratio (B / A) of an initial charge capacity (B) of the first negative electrode active material layer 22 to an initial charge capacity (A) of the positive electrode active material layer 12 is in a range of 0.005 to 0.45.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an all-solid-state secondary battery. [Background technology]

[0002] Recently, industrial demands have led to the active development of batteries with high energy density and safety. For example, lithium batteries are being used not only in the fields of information-related equipment and communication equipment, but also in the automotive field. In the automotive field, safety is of particular importance because life depends on it.

[0003] Lithium batteries use an electrolyte solution containing a flammable organic solvent, so if a short circuit occurs, there is a risk of overheating and fire.

[0004] All-solid-state batteries using solid electrolytes instead of liquid electrolytes have been proposed.

[0005] By not using flammable organic solvents, solid-state batteries can significantly reduce the risk of fire or explosion in the event of a short circuit, making them significantly safer than lithium batteries that use liquid electrolytes. Summary of the Invention [Problem to be solved by the invention]

[0006] Secondary batteries use sulfur-based materials (e.g., S) as the positive electrode active material to increase capacity. During the charge / discharge process of the secondary battery, polysulfides are generated from the sulfur-based materials, which then migrate to the negative electrode and react with it. This side reaction reduces the lifespan of the secondary battery. Therefore, a secondary battery that can suppress the side reaction between polysulfides and lithium metal is required.

[0007] In secondary batteries containing sulfur-based materials (e.g., S), the volume of the sulfur-based material increases during initial discharge and then decreases again during charging. As the volume of the sulfur-based material increases, the ion and / or electron transport pathways within the electrode may be disrupted. Such disruption of the ion and / or electron transport pathways causes deterioration of the secondary battery. Therefore, a secondary battery that can suppress such disruption of the ion and / or electron transport pathways is required.

[0008] Defects occur in the solid electrolyte layer during the manufacturing process and / or charge / discharge process of a secondary battery, and cracks occur and grow from these defects in the solid electrolyte layer. Lithium grows through these cracks, causing a short circuit. A secondary battery that can suppress the occurrence of such defects during the manufacturing process and / or charge / discharge process of the secondary battery is needed.

[0009] The problem to be solved by the present invention is to provide a secondary battery with a novel structure that prevents side reactions between an electrolyte layer and lithium metal during charging and discharging, suppresses disruption of ion and / or electron transport pathways, prevents side reactions caused by polysulfides during charging and discharging, and suppresses the occurrence of defects in the secondary battery during manufacturing and / or charging and discharging. [Means for solving the problem]

[0010] In one embodiment, the battery includes a positive electrode layer, a negative electrode layer, and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer, wherein the positive electrode layer includes a positive electrode current collector and a positive electrode active material layer disposed on one or both sides of the positive electrode current collector, the positive electrode active material layer including a lithium-containing sulfide-based positive electrode active material, the lithium-containing sulfide-based positive electrode active material including LiS, a LiS-containing composite, or a combination thereof, and a first inactive member disposed on one side of the positive electrode layer, and the negative electrode layer includes a negative electrode current collector and a first negative electrode active material layer disposed on one side of the negative electrode current collector, wherein a ratio (B / A) of an initial charge capacity (B) of the first negative electrode active material layer to an initial charge capacity (A) of the positive electrode active material layer is 0.005 to 0.45, and the initial charge capacity of the positive electrode active material layer isst open circuit voltage) to Li / Li + The initial charge capacity of the negative electrode active material layer is determined by charging the negative electrode active material layer to a maximum charging voltage (2 nd open circuit voltage) to Li / Li + An all-solid-state secondary battery is provided, which is determined by charging to 0.01 V with respect to the [Effects of the Invention]

[0011] According to the all-solid-state secondary battery having the novel structure of the present invention, it is possible to provide an all-solid-state secondary battery in which short circuits are suppressed and cycle characteristics are improved. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a cross-sectional view of an all-solid-state secondary battery according to an exemplary embodiment. [Figure 2] FIG. 1 is a cross-sectional view of an all-solid-state secondary battery according to an exemplary embodiment. [Figure 3] FIG. 1 is a cross-sectional view of a bi-cell all-solid-state secondary battery according to an exemplary embodiment. [Figure 4] FIG. 1 is a schematic diagram of an all-solid-state secondary battery positive electrode layer according to an exemplary embodiment. [Figure 5] FIG. 1 is a schematic diagram partially illustrating the interior of an all-solid-state secondary battery according to an exemplary embodiment. [Figure 6] FIG. 1 is a cross-sectional view of an all-solid-state secondary battery according to an exemplary embodiment. [Figure 7] FIG. 1 is a cross-sectional view of an all-solid-state secondary battery according to an exemplary embodiment. [Figure 8] FIG. 1 is a cross-sectional view of a bi-cell all-solid-state secondary battery according to an exemplary embodiment. [Figure 9] FIG. 1 is a cross-sectional view of a stacked bi-cell all-solid-state secondary battery stack according to an exemplary embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] Various embodiments are illustrated in the accompanying drawings. However, the present invention may be embodied in various other forms and should not be construed as limited to the embodiments set forth herein. Rather, these examples are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present invention to those skilled in the art. Like reference numerals refer to like elements throughout.

[0014] When an element is referred to as being "on" another element, it will be understood that it may be directly on top of the other element, or that there may be other intervening elements. In contrast, when an element is referred to as being "directly on" another element, there are no intervening elements.

[0015] Terms such as "first," "second," and "third" may be used herein to describe various components, components, regions, layers, and / or sections, but these components, components, regions, layers, and / or sections should not be limited by these terms. These terms are used only to distinguish one component, component, region, layer, or section from another component, component, region, layer, or section. Thus, a first component, component, region, layer, or section described below could be referred to as a second component, component, region, layer, or section without departing from the teachings of this specification.

[0016] The terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the invention. As used herein, the singular forms "a," "an," "the ...

[0017] Herein, spatially relative terms such as "below," "lower," "bottom," "top," "upper," and "top" may be used to easily describe the relationship of one component or feature to another. It will be understood that spatially relative terms are intended to encompass different orientations of the device when used or operated in addition to the orientation shown. For example, if the device in the drawings were inverted, a component described as "below" or "below" another component or feature would be oriented "above" that other component or feature. Thus, the exemplary term "below" can encompass both an up and down orientation. The device could be otherwise oriented (rotated 90 degrees or in another direction), and the spatially relative terms used herein would be interpreted accordingly.

[0018] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by a person of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms as defined in commonly used dictionaries should be interpreted to have a meaning consistent with their meaning in the context of the relevant art and this disclosure, and should not be interpreted in an idealized or overly formal sense.

[0019] Embodiments are described herein with reference to cross-sectional illustrations that are schematic illustrations of idealized embodiments. Therefore, variations from the shapes of the illustrations are to be expected as a result, for example, of manufacturing techniques and / or tolerances. Therefore, the examples described herein should not be construed as limited to the particular shapes of regions as illustrated herein but should include, for example, deviations in shapes resulting from manufacturing. For example, a region illustrated or described as flat may typically have rough and / or non-linear characteristics. Furthermore, corners illustrated as sharp may also be rounded. Therefore, the illustrated regions are schematic in nature, and the shapes are not intended to illustrate the precise shapes of the regions and are not intended to limit the scope of the claims.

[0020] "Group" means a group of the Periodic Table of the Elements according to the International Union of Pure and Applied Chemistry ("IUPAC") Group 1-18 classification system.

[0021] As used herein, "particle size" refers to the average diameter when the particles are spherical, and refers to the average major axis length when the particles are non-spherical. Particle size can be measured using a particle size analyzer (PSA). "Particle size" refers to, for example, the average particle size. "Average particle size" refers to, for example, D50, which is the median particle size.

[0022] D50 is the particle size corresponding to 50% cumulative volume calculated from the particle side having a small particle size in the particle size distribution measured by a laser diffraction method.

[0023] D90 is the particle size corresponding to 90% cumulative volume calculated from the particle side having a small particle size in the particle size distribution measured by a laser diffraction method.

[0024] D10 is a particle size corresponding to 10% cumulative volume calculated from the particle side having a small particle size in the particle size distribution measured by a laser diffraction method.

[0025] In this disclosure, "metal" includes both metals and metalloids such as silicon and germanium, in either the elemental or ionic state.

[0026] In this disclosure, "alloy" means a mixture of two or more metals.

[0027] In this disclosure, "electrode active material" means an electrode material that can undergo lithiation and delithiation.

[0028] In this disclosure, "positive electrode active material" refers to a positive electrode material that can undergo lithiation and delithiation.

[0029] In this disclosure, "negative electrode active material" means a negative electrode material that can undergo lithiation and delithiation.

[0030] In this disclosure, "lithiation" and "lithiating" refer to the process of adding lithium to an electrode active material.

[0031] As used herein, "delithiation" and "delithiating" refer to the process of removing lithium from an electrode active material.

[0032] In this disclosure, "charge" and "charging" refer to the process of providing electrochemical energy to a battery.

[0033] In this disclosure, "discharge" and "discharging" refer to the process of removing electrochemical energy from a battery.

[0034] In this disclosure, "positive electrode" and "cathode" refer to the electrode where electrochemical reduction and lithiation occurs during the discharge process.

[0035] In this disclosure, "negative electrode" and "anode" refer to the electrodes where electrochemical oxidation and delithiation occurs during the discharge process.

[0036] While particular embodiments have been described above, presently unforeseen or unanticipated alternatives, modifications, variations, improvements, and substantial equivalents may occur to applicant or those skilled in the art. Accordingly, the appended claims, as filed and as they may be amended, are intended to cover all such alternatives, modifications, variations, improvements, and substantial equivalents.

[0037] All-solid-state secondary batteries according to exemplary embodiments will be described in further detail below.

[0038] [All-solid-state secondary battery] an all-solid-state secondary battery according to one embodiment, comprising: a positive electrode layer; a negative electrode layer; and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer; the positive electrode layer comprises a positive electrode current collector and a positive electrode active material layer disposed on one or both sides of the positive electrode current collector; the positive electrode active material layer comprises a lithium-containing sulfide-based positive electrode active material, the lithium-containing sulfide-based positive electrode active material comprising LiS, a LiS-containing composite, or a combination thereof; and a first inactive member disposed on one side of the positive electrode layer; the negative electrode layer comprises a negative electrode current collector and a first negative electrode active material layer disposed on one side of the negative electrode current collector; a ratio (B / A) of an initial charge capacity (B) of the first negative electrode active material layer to an initial charge capacity (A) of the positive electrode active material layer is 0.005 to 0.45; and the initial charge capacity of the positive electrode active material layer is 0.005 to 0.45; and st open circuit voltage) to Li / Li + The initial charge capacity of the negative electrode active material layer is determined by charging the negative electrode active material layer to a maximum charging voltage (2 nd open circuit voltage) to Li / Li + It is determined by charging to 0.01V.

[0039] The all-solid-state secondary battery contains a lithium-containing sulfide-based positive electrode active material instead of lithium metal as a lithium source. This allows the anode layer to omit a lithium source such as lithium metal. The volume of the anode layer is reduced, thereby improving the energy density of the all-solid-state secondary battery.

[0040] The all-solid-state secondary battery includes a lithium-containing sulfide-based positive electrode active material as a positive electrode active material. Therefore, disruption of ion and / or electron transport pathways due to volume increase during initial discharge of a non-lithium-containing sulfide-based positive electrode active material, such as sulfur (S), is prevented. By preventing such disruption of ion and / or electron transport pathways, the cycle characteristics of the all-solid-state secondary battery are improved.

[0041] The all-solid-state secondary battery includes a first anode active material layer having an initial charge capacity in the range of 0.005 to 0.45 relative to the initial charge capacity of the positive electrode active material layer. Because the first anode active material layer has a small initial charge capacity in such a range, the negative electrode layer can effectively compensate for volumetric changes in the positive electrode layer during charge and discharge. As a result, the overall volumetric change of the all-solid-state secondary battery during charge and discharge is suppressed. Since deterioration such as crack generation due to sudden volumetric changes during charge and discharge of the all-solid-state secondary battery is prevented, short-circuiting of the all-solid-state secondary battery is prevented, and the cycle characteristics are improved.

[0042] The inclusion of a solid electrolyte layer in an all-solid-state secondary battery blocks the migration of polysulfides, which are generated during charging and discharging of a lithium-containing sulfide-based positive electrode active material, to the negative electrode layer, thereby suppressing side reactions between the polysulfides and the negative electrode active material.

[0043] By disposing an inactive member on one side of the positive electrode layer, cracks in the solid electrolyte layer that occur when the all-solid-state secondary battery is pressurized and / or when it is charged and discharged are suppressed. Therefore, cracks in the solid electrolyte layer are suppressed during the manufacturing and / or charging and discharging of the all-solid-state secondary battery, thereby suppressing short circuits in the all-solid-state secondary battery. As a result, short circuits in the all-solid-state secondary battery are prevented, and the life characteristics are improved.

[0044] 1 to 9, the all-solid-state secondary battery 1 includes a positive electrode layer 10, a negative electrode layer 20, and a solid electrolyte layer 30 disposed between the positive electrode layer 10 and the negative electrode layer 20. The positive electrode layer 10 includes a positive electrode current collector 11 and a positive electrode active material layer 12 disposed on one or both sides of the positive electrode current collector. The positive electrode active material layer 12 includes a sulfide-based positive electrode active material, which includes Li2S, a Li2S-containing composite, or a combination thereof. The all-solid-state secondary battery 1 includes a first inactive member 40 disposed on one side of the positive electrode layer 10. The negative electrode layer 20 includes a negative electrode current collector 21 and a first negative electrode active material layer 22 disposed on one side of the negative electrode current collector. The ratio (B / A) of the initial charge capacity (B) of the first negative electrode active material layer 22 to the initial charge capacity (A) of the positive electrode active material layer 12 is 0.005 to 0.45. The initial charge capacity of the positive electrode active material layer 12 is determined by the first open circuit voltage (1 st open circuit voltage) to Li / Li + The initial charge capacity of the first negative electrode active material layer 22 is determined by charging the first negative electrode active material layer 22 to a maximum charging voltage (2 nd open circuit voltage) to Li / Li + The ratio (B / A) of the initial charge capacity (B) of the first negative electrode active material layer 22 to the initial charge capacity (A) of the positive electrode active material layer 12 is, for example, 0.01 to 0.4, 0.01 to 0.3, 0.01 to 0.2, or 0.01 to 0.1.

[0045] [Positive electrode layer] [Cathode layer: Cathode active material] 1 to 9, the positive electrode active material layer 12 includes, for example, a positive electrode active material and a solid electrolyte. The solid electrolyte included in the positive electrode active material layer 12 may be similar to or different from the solid electrolyte included in the solid electrolyte layer 30. For details about the solid electrolyte, please refer to the section on the solid electrolyte layer 30.

[0046] The positive electrode active material includes a lithium-containing sulfide-based positive electrode active material. The lithium-containing sulfide-based positive electrode active material is, for example, an electrode material in which lithium is added to a sulfur-based positive electrode active material. The sulfur-based positive electrode active material includes, for example, a sulfur-based material, a sulfur-based material-containing composite, or a combination thereof. The sulfur-based material can be, for example, inorganic sulfur, Li2Sn(n>1), a disulfide compound, an organic sulfur compound, a carbon-sulfur polymer, or a combination thereof. The sulfur-based material-containing composite can be, for example, a composite containing inorganic sulfur, Li2Sn(n>1), a disulfide compound, an organic sulfur compound, a carbon-sulfur polymer, or a combination thereof. The sulfur-based material-containing composite may include, for example, a composite of a sulfur-based material and carbon, a composite of a sulfur-based material, carbon, and a solid electrolyte, a composite of a sulfur-based material, carbon, and a lithium salt, a composite of a sulfur-based material and a lithium salt, a composite of a sulfur-based material and a solid electrolyte, a composite of a sulfur-based material and a metal carbide, a composite of a sulfur-based material, carbon, and a metal carbide, a composite of a sulfur-based material and a metal nitride, a composite of a sulfur-based material, carbon, and a metal nitride, or a combination thereof. Lithium-containing sulfide-based positive electrode active materials provide a higher discharge capacity per unit weight than oxide-based positive electrode active materials, and therefore the energy density per unit weight of all-solid-state secondary batteries containing the lithium-containing sulfide-based positive electrode active material may be improved.

[0047] The lithium-containing sulfide-based positive electrode active material includes, for example, Li2S, a Li2S-containing composite, or a combination thereof. By including Li2S, a Li2S-containing composite, or a combination thereof, which have high capacity, as the lithium-containing sulfide-based positive electrode active material, the use of lithium metal can be omitted when manufacturing an all-solid-state secondary battery. Lithium metal has high reactivity and high ductility, which can reduce mass productivity during battery manufacturing. Therefore, the mass productivity of all-solid-state secondary batteries can be improved. By omitting lithium metal from the anode layer and reducing the volume of the anode layer, the energy density per unit volume of the all-solid-state secondary battery can be improved, and an all-solid-state secondary battery with a simpler structure can be constructed.

[0048] Lithium-containing sulfide-based positive electrode active materials (e.g., LiS) undergo delithiation during initial charging, reducing their volume, and then increase their volume again during subsequent discharge due to lithiation. Therefore, the volume of the lithium-containing sulfide-based positive electrode active material changes while maintaining the ion and / or electron transport pathways provided by, for example, a conductive material disposed around the lithium-containing sulfide-based positive electrode active material, reducing the likelihood of the ion and / or electron transport pathways being interrupted. In contrast, sulfur-based positive electrode active materials (e.g., S) undergo lithiation during initial discharging, increasing their volume, and then decrease their volume again during subsequent charging due to delithiation. Therefore, the initial ion and / or electron transport pathways provided by, for example, a conductive material disposed around the sulfur-based positive electrode active material may be disrupted by the initial volume increase of the sulfur-based positive electrode active material, reducing the likelihood of the ion and / or electron transport pathways being interrupted.

[0049] The particle size of the lithium-containing sulfide-based positive electrode active material is, for example, 1 nm to 50 μm, 10 nm to 50 μm, 50 nm to 40 μm, 100 nm to 30 μm, 500 nm to 30 μm, or 1 μm to 20 μm. When the lithium-containing sulfide-based positive electrode active material has a particle size within such a range, the cycle characteristics of an all-solid-state secondary battery containing the lithium sulfide-based positive electrode active material can be further improved. The Li2S-containing composite is, for example, a composite of Li2S and a conductive material. The conductive material is, for example, an ion-conductive material, an electron-conductive material, or a combination thereof.

[0050] The electronic conductivity of the electronic conductive material is, for example, 1.0×10 3 S / m, 1.0×10 4 S / m, or 1.0 x 10 5The conductivity is S / m or more. The form of the electronically conductive material may be, for example, a particulate electronically conductive material, a plate-like electronically conductive material, a rod-like electronically conductive material, or a combination thereof, but is not necessarily limited thereto. The electronically conductive material may also be, for example, carbon, a metal powder, a metal compound, etc. When carbon is included as the electronically conductive material, carbon has high electronic conductivity and is light, making it possible to realize an all-solid-state secondary battery with a high energy density per unit mass. The electronically conductive material may have pores. When the electronically conductive material has pores, Li2S is contained in the pores, increasing the contact area between Li2S and the electronically conductive material and increasing the specific surface area of ​​Li2S. The pore volume is, for example, 0.1 cc / g to 20.0 cc / g, 0.5 cc / g to 10 cc / g, or 0.5 cc / g to 5 cc / g. The average pore diameter is, for example, 1 nm to 100 nm, 1 nm to 50 nm, or 1 nm to 20 nm. The BET specific surface area of ​​the porous electronic conductive material is 200 m when the average pore diameter is 15 nm or less. 2 / g~4500m 2 / g, and if the average pore diameter is greater than 15 nm, 2 / g~2500m 2 The BET specific surface area, pore diameter, pore volume and average pore diameter can be determined, for example, by using a nitrogen adsorption method.

[0051] The ionic conductivity of the ion-conductive material is, for example, 1.0×10 -5 S / m, 1.0×10 -4 S / m, or 1.0 x 10 -3The ionic conductivity is S / m or more. The ion conductive material may have pores. By having pores, Li2S can be contained within the pores, increasing the contact area between the Li2S and the ion conductive material and increasing the specific surface area of ​​the Li2S. The ion conductive material may be, for example, but is not limited to, a particulate ion conductive material, a plate-shaped electronic conductive material, a rod-shaped electronic conductive material, or a combination thereof. The ion conductive material may also be, for example, a sulfide-based solid electrolyte or an oxide-based solid electrolyte. When a sulfide-based solid electrolyte is included as the ion conductive material, the sulfide-based solid electrolyte has high ionic conductivity and can be formed into various shapes, making it possible to realize an all-solid-state secondary battery with a large capacity.

[0052] Examples of LiS-containing composites include a composite of LiS and carbon, a composite of LiS and carbon and a solid electrolyte, a composite of LiS and a solid electrolyte, a composite of LiS and carbon and a lithium salt, a composite of LiS and a lithium salt, a composite of LiS and a metal carbide, a composite of LiS and carbon and a metal carbide, a composite of LiS and a metal nitride, a composite of LiS and carbon and a metal nitride, or a combination thereof. LiS-containing composites are distinguished from simple mixtures of LiS with carbon, a solid electrolyte, a lithium salt, a metal carbide, a metal nitride, or the like. Simple mixtures of LiS with carbon, a solid electrolyte, a lithium salt, a metal carbide, a metal nitride, or the like do not maintain a dense interface between LiS and other components, resulting in high interfacial resistance and potentially reducing the lifespan characteristics of all-solid-state secondary batteries.

[0053] The Li2S and carbon composite contains carbon. Any carbon-containing material commonly used as a conductive material in the art can be used. Examples of the carbon include crystalline carbon, amorphous carbon, or a combination thereof. Examples of the carbon include a calcined carbon precursor. Examples of the carbon include carbon nanostructures. Examples of the carbon nanostructures include one-dimensional carbon nanostructures, two-dimensional carbon nanostructures, three-dimensional carbon nanostructures, or a combination thereof. Examples of the carbon nanostructures include carbon nanotubes, carbon nanofibers, carbon nanobelts, carbon nanorods, graphene, or a combination thereof. Examples of the carbon include porous carbon or non-porous carbon. Porous carbon may include, for example, periodic and regular two-dimensional or three-dimensional pores. Examples of the porous carbon include carbon black, such as Ketjen Black, Acetylene Black, Denka Black, Thermal Black, and Channel Black; graphite; activated carbon; or a combination thereof. The form of carbon may be, for example, particulate, sheet, flake, etc., but is not limited thereto, and any method used in the art for carbon may be used. The method for producing a LiS and carbon composite may be, for example, a dry method, a wet method, or a combination thereof, but is not limited thereto, and the method for producing a LiS and carbon composite in the art may be, for example, milling, heat treatment, vapor deposition, etc., but is not necessarily limited thereto, and any method used in the art may be used.

[0054] The composite of Li2S, carbon, and a solid electrolyte includes carbon and a solid electrolyte. Carbon refers to the composite of Li2S and carbon described above. Any solid electrolyte used as an ion-conducting material in the art can be used. The solid electrolyte is, for example, an inorganic solid electrolyte. The solid electrolyte is, for example, a crystalline solid electrolyte, an amorphous solid electrolyte, or a combination thereof. The solid electrolyte is, for example, a sulfide-based solid electrolyte, an oxide-based solid electrolyte, or a combination thereof. The sulfide-based solid electrolyte contains, for example, Li, S, and P, and may further optionally contain a halogen element. The sulfide-based solid electrolyte can be selected from sulfide-based solid electrolytes used in the solid electrolyte layer. The sulfide-based solid electrolyte has a specific surface area of, for example, 1×10 at room temperature. -5 The oxide-based solid electrolyte has an ionic conductivity of 1×10 S / cm or more at room temperature. The oxide-based solid electrolyte contains, for example, Li, O, and a transition metal element, and may further contain other elements selectively. -5 It is also a solid electrolyte having an ionic conductivity of 5 S / cm or more. The oxide-based solid electrolyte can be selected from oxide-based solid electrolytes used in the solid electrolyte layer.

[0055] The composite of Li2S and a solid electrolyte includes a solid electrolyte, which refers to the above-mentioned composite of Li2S, carbon, and a solid electrolyte.

[0056] The complex of Li2S, carbon, and a lithium salt includes Li2S, carbon, and a lithium salt. The carbon refers to the complex of Li2S and carbon described above. The lithium salt is a compound that does not contain sulfur (S). The lithium salt can also be, for example, a binary compound consisting of lithium and one element selected from Groups 13 to 17 of the periodic table. The binary compound can include, for example, one or more elements selected from LiF, LiCl, LiBr, LiI, LiH, Li2S, Li2O, Li2Se, Li2Te, Li3N, Li3P, Li3As, Li3Sb, Li3Al2, and LiB3. The lithium salt can also be, for example, a ternary compound consisting of lithium and two elements selected from Groups 13 to 17 of the periodic table. Ternary compounds include, for example, one or more selected from Li3OCl, LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiAlO2, LiAlCl4, LiNO3, Li2CO3, LiBH4, Li2SO4, Li3BO3, Li3PO4, Li4NCl, Li5NCl2, and Li3BN2. The lithium salt is, in particular, one or more lithium halide compounds selected from LiF, LiCl, LiBr, and LiI. A composite of Li2S, carbon, and a lithium salt can also be, for example, a composite of Li2S, carbon, and a lithium halide. The inclusion of a lithium halide compound in the composite of Li2S, carbon, and a lithium salt can provide improved ionic conductivity. A composite of Li2S, carbon, and a lithium salt is distinguished from a simple mixture of Li2S, carbon, and a lithium salt. A simple mixture of Li2S, carbon, and a lithium salt does not maintain a dense interface between Li2S, carbon, and the lithium salt, which can provide high interfacial resistance and consequently reduce the life characteristics of the all-solid-state secondary battery.

[0057] The composite of Li2S and a lithium salt includes a lithium salt, which refers to the lithium salt used in the above-described composite of Li2S, carbon, and a lithium salt.

[0058] The composite of Li2S and metal carbide includes a metal carbide. The metal carbide is, for example, a two-dimensional metal carbide. The two-dimensional metal carbide is, for example, Mn+1 C n T x (M is a transition metal, T is an end group, T is O, OH and / or F, n=1, 2 or 3, x is the number of end groups). Two-dimensional metal carbides are, for example, Ti2CT x , (Ti 0.5 , Nb 0.5 )2CT x , Nb2CT x , V2CT x , Ti3C2T x , (V 0.5 , Cr 0.5 )3C2T x , Ti3CNT x , Ta4C3T x , Nb4C3T x or a combination thereof. The surface of the two-dimensional metal carbide is terminated with O, OH and / or F.

[0059] The composite of Li2S, carbon, and metal carbide includes carbon and metal carbide. Carbon refers to the composite of Li2S and carbon described above. Metal carbide refers to the composite of Li2S and metal carbide described above.

[0060] The composite of Li2S and a metal nitride includes a metal nitride. The metal nitride is, for example, a two-dimensional metal nitride. The two-dimensional metal nitride is, for example, M n+1 N n T x (M is a transition metal, T is a terminal group, T is O, OH and / or F, n=1, 2 or 3, x is the number of terminal groups). The surface of the two-dimensional metal nitride is terminated with O, OH and / or F.

[0061] The composite of Li2S, carbon, and metal nitride includes carbon and metal nitride. Carbon refers to the composite of Li2S and carbon described above. Metal carbide refers to the composite of Li2S and metal nitride described above.

[0062] The content of the sulfide-based positive electrode active material in the positive electrode active material layer 12 is, for example, 10 wt% to 90 wt%, 10 wt% to 80 wt%, 10 wt% to 70 wt%, 10 wt% to 60 wt%, or 10 wt% to 50 wt% of the total weight of the positive electrode active material layer 12.

[0063] The positive electrode active material layer 12 may further include a sulfide-based compound classified as Li2S. The sulfide-based compound may be, for example, a compound containing a metal element other than Li and sulfur. The sulfide-based compound may be, for example, a compound containing a metal element belonging to Groups 1 to 14 of the Periodic Table of Elements with an atomic weight of 10 or more and sulfur. The sulfide-based compound may be, for example, FeS2, VS2, NaS, MnS, FeS, NiS, CuS, or a combination thereof. When the positive electrode active material layer further includes a sulfide-based compound, the cycle characteristics of the all-solid-state secondary battery may be further improved. The content of the sulfide-based compound classified as Li2S contained in the positive electrode active material layer 12 may be 10 wt% or less, 5 wt% or less, 3 wt% or less, or 1 wt% or less of the total weight of the positive electrode active material layer 12.

[0064] [Positive electrode layer: solid electrolyte] 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 about the solid electrolyte, see the section on the solid electrolyte layer 30.

[0065] The solid electrolyte contained in the positive electrode active material layer 12 has a smaller D50 average particle size than the solid electrolyte contained in the solid electrolyte layer 30. For example, the D50 average particle size of the solid electrolyte contained in the positive electrode active material layer 12 is 90% or less, 80% or less, 70% or less, 60% or less, 50% or less, 40% or less, 30% or less, or even 20% or less of the D50 average particle size of the solid electrolyte contained in the solid electrolyte layer 30. The D50 average particle size is, for example, the median particle size (D50). The median particle size (D50) is the particle size corresponding to a 50% cumulative volume calculated from the small particle side in a particle size distribution measured by, for example, a laser diffraction method.

[0066] The content of the solid electrolyte in the positive electrode active material layer 12 is, 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.

[0067] [Positive electrode layer: conductive material] 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 thereto, and any material used as a carbon-based conductive material in the art may be used. The metal-based conductive material may be, for example, metal powder, metal fiber, or a combination thereof, but is not limited thereto, and any material used as a metal-based conductive material in the art may be used. The conductive material content of 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.

[0068] [Positive electrode layer: binder] The positive electrode active material layer 12 may further include a binder. Examples of binders include, but are not limited to, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, and polyethylene. Any binder commonly used in the art may be used. The content of the binder in the positive electrode active material layer 12 is, for example, 1 wt % to 10 wt % of the total weight of the positive electrode active material layer 12. The binder may be omitted.

[0069] [Positive electrode layer: Other additives] The positive electrode active material layer 12 may further contain additives such as a filler, a coating agent, a dispersant, and an ion-conductive auxiliary agent in addition to the above-mentioned positive electrode active material, solid electrolyte, binder, and conductive material.

[0070] As the filler, coating agent, dispersant, ion-conducting auxiliary agent, etc. contained in the positive electrode active material layer 12, known materials generally used in electrodes of all-solid-state secondary batteries can be used.

[0071] [Positive electrode layer: Positive electrode current collector] The positive electrode current collector 11 is, for example, a plate or foil made of indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), or an alloy thereof. The positive electrode current collector 11 can be omitted. The thickness of the positive electrode current collector 11 is, for example, 1 μm to 100 μm, 1 μm to 50 μm, 5 μm to 25 μm, or 10 μm to 20 μm.

[0072] The positive electrode current collector 11 includes, 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 also include, 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 also be, for example, an insulator. When the base film includes an insulating thermoplastic polymer, the base film softens or liquefies in the event of a short circuit, thereby shutting down 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 acts as an electrochemical fuse, breaking in the event of an overcurrent and preventing short circuits. The limiting current and maximum current can be adjusted by adjusting the thickness of the metal layer. The metal layer is electrodeposited or vapor-deposited on the base film. A thinner metal layer reduces the limiting current and / or maximum current of the positive electrode current collector 11, thereby improving the stability of the lithium battery during a short circuit. A lead tab can be added to the metal layer for external connection. The lead tab is 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 melts, electrically connecting the metal layer to the lead tab. A metal chip can be added between the metal layer and the lead tab to strengthen the weld between the metal layer and the lead tab. The metal chip can also be a thin piece of the same material as the metal of the metal layer. The metal piece may be, for example, a metal foil, a metal mesh, etc. The metal piece may be, for example, an aluminum foil, a copper foil, a SUS foil, etc.After placing a metal piece on the metal layer, the lead tab is welded to the metal piece / metal layer laminate or the metal piece / metal layer / base film laminate. During welding, the base film, metal layer, and / or metal piece melt, electrically connecting the metal layer or the metal layer / metal piece laminate to the lead tab. The metal piece 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. The base film having a thickness within this range can more effectively reduce the weight of the electrode assembly. The melting point of the base film may be, for example, 100 to 300°C, 100 to 250°C, or 100 to 200°C. When the base film has a melting point within this range, the base film melts during the lead tab welding process and can be easily bonded to the lead tab. To improve the adhesion between the base film and the metal layer, a surface treatment such as a corona treatment may be performed on the base film. 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. When 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. When the metal piece has a thickness within this range, the connection between the metal layer and the lead tab can be more easily achieved. When the positive electrode current collector 11 has such a structure, the weight of the positive electrode can be reduced, thereby improving the energy density of the positive electrode and the lithium battery.

[0073] [Positive electrode layer: first inactive member] Referring to FIG. 1, the positive electrode layer 10 includes a positive electrode current collector 11 and a positive electrode active material layer 12 disposed on one side of the positive electrode current collector. A first inactive member 40 is disposed on one side of the positive electrode layer 10. The first inactive member 40 is disposed on one side of the positive electrode active material layer 12 and one side of the positive electrode current collector 11. Referring to FIG. 2, the first inactive member 40 is disposed on one side of the positive electrode active material layer 12 and is disposed between the solid electrolyte layer 30 and the positive electrode current collector 11 facing the solid electrolyte layer 30. The first inactive member 40 is not disposed on one side of the positive electrode current collector 11.

[0074] The inclusion of the first inactive member 40 prevents cracks in the solid electrolyte layer 30 during manufacture of the all solid state secondary battery 1 and / or during charge and discharge, resulting in improved cycle characteristics of the all solid state secondary battery 1. In an all solid state secondary battery 1 that does not include the first inactive member 40, uneven pressure is applied to the solid electrolyte layer 30 that contacts the positive electrode layer 10 during manufacture of the all solid state secondary battery 1 and / or during charge and discharge, causing cracks in the solid electrolyte layer 30, increasing the possibility of short circuits occurring due to the growth of lithium metal through these cracks.

[0075] In the all-solid-state secondary battery 1, the thickness T2 of the first inactive member 40 is thinner than or equal to the thickness T1 of the positive electrode active material layer 12. In the all-solid-state secondary battery 1, the thickness T2 of the first inactive member 40 is substantially equal to the thickness T3 of the positive electrode layer 10. Because the thickness T2 of the first inactive member 40 is equal to the thickness T3 of the positive electrode layer 10, a uniform pressure is applied between the positive electrode layer 10 and the solid electrolyte layer 30, the positive electrode layer 10 and the solid electrolyte layer 30 are sufficiently adhered to each other, and the interfacial resistance between the positive electrode layer 10 and the solid electrolyte layer 30 is reduced. In addition, the solid electrolyte layer 30 is sufficiently sintered during the pressurized manufacturing process of the all-solid-state secondary battery 1, thereby reducing the internal resistance of the solid electrolyte layer 30 and the all-solid-state secondary battery 1 including it.

[0076] The first inactive member 40 surrounds the side surfaces of the positive electrode layer 10 and contacts the solid electrolyte layer 30. By surrounding the side surfaces of the positive electrode layer 10 and contacting the solid electrolyte layer 30, cracks in the solid electrolyte layer 30 that are not in contact with the positive electrode layer 10 due to a pressure difference during a pressing process can be effectively suppressed. The first inactive member 40 surrounds the side surfaces of the positive electrode layer 10 and separates it from the anode layer 20, more specifically, the first anode active material layer 22. The first inactive member 40 surrounds the side surfaces of the positive electrode layer 10 and contacts the solid electrolyte layer 30, separating it from the anode layer 20. Therefore, the possibility of a short circuit occurring due to physical contact between the positive electrode layer 10 and the first anode active material layer 22 or the like is suppressed. For example, by arranging the inactive member 40 on one side of the positive electrode active material layer 12 and also on one side of the positive electrode current collector 11, the possibility of a short circuit occurring due to contact between the positive electrode current collector 11 and the negative electrode layer 20 is more effectively suppressed.

[0077] 1 to 5 , the first inactive members 40, 40a, and 40b extend from one side of the positive electrode layer 10 to an end portion of the solid electrolyte layer 30. By extending the first inactive member 40 to the end portion of the solid electrolyte layer 30, it is possible to suppress the occurrence of cracks at the end portion of the solid electrolyte layer 30. The end portion of the solid electrolyte layer 30 is the outermost portion that contacts the side surface of the solid electrolyte layer 30. The first inactive member 40 extends to the outermost portion that contacts the side surface of the solid electrolyte layer 30. The first inactive member 40 is separated from the negative electrode layer 20, more specifically, the first negative electrode active material layer 22. The first inactive member 40 extends to the end portion of the solid electrolyte layer 30 but does not contact the negative electrode layer 20. The first inactive member 40 fills a space that extends from one side of the positive electrode layer 10 to the end portion of the solid electrolyte layer 30, for example.

[0078] 1 and 2, the width W2 of the first inactive member 40 extending from one side of the positive electrode layer 10 to an end portion of the solid electrolyte layer 30 is, for example, 1 to 30%, 1 to 25%, 1 to 20%, 1 to 15%, 1 to 10%, or 1 to 5% of the width W1 between one side of the positive electrode layer 10 and the other side opposite the one side. Referring to FIGS. 1 and 2, the width W2 of the first inactive member 40 extending from one side of the positive electrode layer 10 to an end portion of the solid electrolyte layer 30 is, for example, 1 to 30%, 3 to 30%, 5 to 30%, 5 to 20%, 5 to 15%, or 5 to 10% of the width W1 between one side of the positive electrode layer 10 and the other side opposite the one side. If the width W2 of the first inactive member 40 is excessively large, the energy density of the all-solid-state secondary battery 1 decreases. If the width W2 of the first inert member 40 is too small, the effect of arranging the first inert member 40 is negligible.

[0079] The area S1 of the positive electrode layer 10 is smaller than the area S3 of the solid electrolyte layer 30 in contact with the positive electrode layer 10. The flame-retardant inert member 40 surrounds the sides of the positive electrode layer 10, compensating for the difference in area between the positive electrode layer 10 and the solid electrolyte layer 30. The area S2 of the flame-retardant inert member 40 compensates for the difference between the area S1 of the positive electrode layer 10 and the area S3 of the solid electrolyte layer 30, thereby effectively suppressing cracks in the solid electrolyte layer 30 caused by the pressure difference during the pressing process. For example, the sum of the area S1 of the positive electrode layer 10 and the area S2 of the inert member 40 is the same as the area S3 of the solid electrolyte layer 30.

[0080] The area S1 of the positive electrode layer 10 is, for example, less than 100%, 99% or less, 98% or less, 97% or less, 96% or less, or 95% or less of the area S3 of the solid electrolyte layer 30. The area S1 of the positive electrode layer 10 is, for example, 50% to less than 100%, 50% to 99%, 55% to 98%, 60% to 97%, 70% to 96%, 80% to 95%, or 85% to 95% of the area S3 of the solid electrolyte layer 30.

[0081] If the area S1 of the positive electrode layer 10 is equal to or greater than the area S3 of the solid electrolyte layer 30, a short circuit may occur due to physical contact between the positive electrode layer 10 and the first negative electrode active material layer 22, or the possibility of a short circuit occurring due to lithium overcharging or the like increases. The area S1 of the positive electrode layer 10 is, for example, equal to the area of ​​the positive electrode active material layer 12. The area S1 of the positive electrode layer 10 is, for example, equal to the area of ​​the positive electrode current collector 11.

[0082] The area S2 of the first inactive member 40 is, for example, 50% or less, 40% or less, 30% or less, 20% or less, or 10% or less of the area S1 of the positive electrode layer 10. The area S2 of the first inactive member 40 is, for example, 1% to 50%, 5% to 40%, 5% to 30%, 5% to 20%, or 5% to 15% of the area S1 of the positive electrode layer 10.

[0083] The area S1 of the positive electrode layer 10 is smaller than the area S4 of the negative electrode current collector 21. The area S1 of the positive electrode layer 10 is, for example, less than 100%, 99% or less, 98% or less, 97% or less, 96% or less, or 95% or less of the area S4 of the negative electrode current collector 21. The area S1 of the positive electrode layer 10 is, for example, 50% to less than 100%, 50% to 99%, 55% to 98%, 60% to 97%, 70% to 96%, 80% to 95%, or 85% to 95% of the area S4 of the negative electrode current collector 21. The area S4 of the negative electrode current collector 21 is, for example, the same as the area of ​​the negative electrode layer 20. The area S4 of the negative electrode current collector 21 is, for example, the same as the area of ​​the first negative electrode active material layer 22.

[0084] As used herein, the term "same" area, length, width, thickness, and / or shape includes all cases where the area, length, width, thickness, and / or shape are "substantially the same," except when the area, length, width, thickness, and / or shape are intentionally different from each other. The term "same" area, length, width, and / or thickness includes a range where the unintentional difference between the areas, lengths, widths, and / or thicknesses of the objects being compared is, for example, less than 1%, less than 0.5%, or less than 0.1%.

[0085] The thickness of the first inactive member 40 is, for example, greater than the thickness of the first negative electrode active material layer 22. The thickness of the first negative electrode active material layer 22 is, for example, 50% or less, 40% or less, 30% or less, 20% or less, or 10% or less of the thickness of the first inactive member 40. 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 first inactive member 40.

[0086] The negative electrode layer 20 includes a negative electrode current collector 21 and a first negative electrode active material layer 22 disposed on one surface of the negative electrode current collector 21. For example, the first negative electrode active material layer 22 is free on the other surface opposite to the one surface of the negative electrode current collector 21. For example, the first negative electrode active material layer 22 is disposed only on one surface of the negative electrode current collector 21, and the first negative electrode active material layer 22 is not disposed on the other surface.

[0087] The first inert member 40 is also a gasket. By using a gasket as the inert member 40, cracks in the solid electrolyte layer 30 caused by a pressure difference during the pressing process can be effectively prevented.

[0088] The first inactive member 40 has, for example, a single-layer structure. Alternatively, although not shown, the first inactive member 40 may have a multi-layer structure. In the first inactive member 40 having a multi-layer structure, each layer has a different composition. The first inactive 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 first inactive 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 positive electrode layer 10 and the solid electrolyte layer 30 due to volumetric changes in the positive electrode layer 10 that occur during the charge / discharge process of the all-solid-state secondary battery 1, and improves the film strength of the inactive member 40 by providing binding strength between the support layer and other layers. The support layer provides support to the first inactive member 40 and prevents uneven pressure from being applied to the solid electrolyte layer 30 during the pressurization process or charge / discharge process, thereby preventing deformation of the manufactured all-solid-state secondary battery 1.

[0089] 3, the all-solid-state secondary battery 1 includes a positive electrode layer 10, a negative electrode layers 20, 20a, 20b, and solid electrolyte layers 30, 30a, 30b disposed therebetween. The positive electrode layer 10 includes a positive electrode current collector 11 and a first positive electrode active material layer 12a and a second positive electrode active material layer 12b disposed on both surfaces of the positive electrode current collector 11, respectively. The solid electrolyte layer 30 includes a first solid electrolyte layer 30a in contact with the first positive electrode active material layer 12a and a second solid electrolyte layer 30b in contact with the second positive electrode active material layer 12b, respectively. The negative electrode layer 20 includes a first anode layer 20a in contact with the first solid electrolyte layer 30a and a second anode layer 20b in contact with the second solid electrolyte layer 30b, respectively. A first inactive member 40 is disposed between the opposing first and second solid electrolyte layers 30a and 30b, surrounding the side surfaces of the positive electrode layer 10. The first inactive member 40 includes, for example, a 1a inactive member 40a in contact with the first solid electrolyte layer 30a and a 1b inactive member 40b in contact with the second solid electrolyte layer 30b. Therefore, the all-solid-state secondary battery 1 has a bi-cell structure. The all-solid-state secondary battery 1 has such a bi-cell structure, where the solid electrolyte layer 30 and the anode layer 20 are symmetrically arranged facing each other with the cathode layer 10 at the center. This more efficiently suppresses structural deformation due to pressure applied during the manufacturing process of the all-solid-state secondary battery 1. Therefore, cracks in the solid electrolyte layer 30 during the manufacturing process of the all-solid-state secondary battery 1 and / or during charging and discharging are suppressed, thereby preventing short circuits in the all-solid-state secondary battery 1. As a result, the cycle characteristics of the all-solid-state secondary battery 1 are further improved. Furthermore, since only one cathode current collector 11 is used for multiple cathode active material layers 12a and 12b, the energy density of the all-solid-state secondary battery 1 is increased.

[0090] 1 to 5, the first inactive member 40 is, for example, a flame-retardant inactive member. The flame-retardant inactive member provides flame retardancy, thereby preventing the possibility of thermal runaway and fire in the all-solid-state secondary battery 1. As a result, the safety of the all-solid-state secondary battery 1 is further improved. The flame-retardant inactive member absorbs residual moisture in the all-solid-state secondary battery 1, thereby preventing deterioration of the all-solid-state secondary battery 1 and improving the life characteristics of the all-solid-state secondary battery 1.

[0091] The flame-retardant inert member includes, for example, a matrix and a filler. The matrix includes, for example, a substrate and a reinforcing material. The matrix includes, for example, a fibrous substrate and a fibrous reinforcing material. When the matrix includes the substrate, it can have elasticity. Therefore, the matrix can effectively accommodate volume changes during charge and discharge of the all-solid-state secondary battery 1 and can be arranged in various positions. The substrate included in the matrix includes, for example, a first fibrous material. When the substrate includes the first fibrous material, it can effectively accommodate volume changes in the positive electrode layer 10 that occur during the charge and discharge process of the all-solid-state secondary battery 1 and effectively suppress deformation of the first inert member 40 due to volume changes in the positive electrode layer 10. The first fibrous material is, for example, a material with an aspect ratio of 5 or more, 20 or more, or 50 or more. The first fibrous material is, for example, a material with an aspect ratio of 5 to 1000, 20 to 1000, or 50 to 1000. The first fibrous material is, for example, an insulating material. The insulating first fibrous material can effectively prevent short-circuiting between the positive electrode layer 10 and the negative electrode layer 20 due to lithium dendrites or the like that occur during the charge and discharge process of the all-solid-state secondary battery 1. The first fibrous material includes, for example, one or more selected from pulp fiber, insulating polymer fiber, and ion-conductive polymer fiber. The matrix includes a reinforcing material, which improves the strength of the matrix. Therefore, the matrix can prevent excessive volume change during charge and discharge of the all-solid-state secondary battery 1, thereby preventing deformation of the all-solid-state secondary battery. The reinforcing material included in the matrix includes, for example, a second fibrous material. The reinforcing material includes the second fibrous material, which can further uniformly increase the strength of the matrix. The second fibrous material is, for example, a material with an aspect ratio of 3 or more, 5 or more, or 10 or more. The first fibrous material is, for example, a material with an aspect ratio of 3 to 100, 5 to 100, or 10 to 100. The second fibrous material is, for example, a flame-retardant material. The second fibrous material is a flame-retardant material, which can effectively prevent ignition due to thermal runaway that occurs during the charge / discharge process or due to external impact of the all-solid-state secondary battery 1. Examples of the second fibrous material include glass fiber, metal oxide fiber, and ceramic fiber.

[0092] The flame-retardant inert member includes a filler in addition to the matrix. The filler may be disposed inside the matrix, on the surface of the matrix, or both inside and on the surface. The filler may be, for example, an inorganic material. The filler included in the flame-retardant inert member may be, for example, a moisture getter. The filler adsorbs moisture at temperatures below 100°C, for example, to remove moisture remaining in the all-solid-state secondary battery 1 and prevent deterioration of the all-solid-state secondary battery 1. Furthermore, when the temperature of the all-solid-state secondary battery 1 increases to 150°C or higher due to thermal runaway caused by the charge / discharge process of the all-solid-state secondary battery 1 or an external impact, the filler releases the adsorbed moisture, thereby effectively suppressing ignition of the all-solid-state secondary battery 1. That is, the filler may be, for example, a flame retardant. The filler may be, for example, a metal hydroxide having moisture adsorption properties. The metal hydroxide contained in the filler is, for example, Mg(OH)2, Fe(OH)3, Sb(OH)3, Sn(OH)4, Ti(OH)3, Zr(OH)4, Al(OH)3, or a combination thereof. The content of the filler contained in the flame-retardant inert material is, for example, 10 to 80 parts by weight, 20 to 80 parts by weight, 30 to 80 parts by weight, 40 to 80 parts by weight, 50 to 80 parts by weight, 60 to 80 parts by weight, or 65 to 80 parts by weight, relative to 100 parts by weight of the flame-retardant inert material 4.

[0093] The flame-retardant inert member 40 may further include, for example, a binder. The binder may include, for example, a curable polymer or a non-curable polymer. A curable polymer is a polymer that is cured by heat and / or pressure. The curable polymer is, for example, solid at room temperature. The flame-retardant inert member 40 may include, for example, a heat-pressure-curable film and / or its cured product. An example of a heat-pressure-curable polymer is TSA-66 from Toray Industries.

[0094] The flame-retardant inert member may further include other materials in addition to the above-mentioned substrate, reinforcing material, filler, and binder. The flame-retardant inert member may further include one or more selected from the group consisting of paper, insulating polymers, ion-conducting polymers, insulating inorganic materials, oxide-based solid electrolytes, and sulfide-based solid electrolytes. The insulating polymer may be, for example, an olefin-based polymer such as polypropylene (PP) or polyethylene (PE).

[0095] The density of the substrate or the density of the reinforcing material contained in the flame-retardant inert member is, for example, 10% to 300%, 10% to 150%, 10% to 140%, 10% to 130%, or 10% to 120% of the density of the positive electrode active material contained in the positive electrode active material layer 12.

[0096] The first inactive member 40 is a member that does not contain a material having electrochemical activity, such as an electrode active material. An electrode active material is a material that absorbs / desorbs lithium. The first inactive member 40 is a member that is made of a material other than an electrode active material and is used in the art.

[0097] [Negative electrode layer] [Negative electrode layer: negative electrode active material] 1 to 5, the negative electrode layer 20 includes a first negative electrode active material layer 22. The first negative electrode active material layer 22 includes, for example, a negative electrode active material and a binder.

[0098] The negative electrode active material contained in the first negative electrode active material layer 22 is, for example, a negative electrode material that can form an alloy or compound with lithium.

[0099] The negative electrode active material contained in the first negative electrode active material layer 22 is, for example, particulate. The average particle size of the particulate negative electrode active material is, for example, 4 μm or less, 3 μm or less, 2 μm or less, 1 μm or less, 500 nm or less, 300 nm or less, or 100 nm or less. The average particle size of the particulate negative electrode active material is, for example, 10 nm to 4 μm, 10 nm to 3 μm, 10 nm to 2 μm, 10 nm to 1 μm, 10 nm to 500 nm, 10 nm to 300 nm, or 10 nm to 100 nm. When the negative electrode active material has an average particle size within such a range, reversible absorbing and / or desorbing of lithium during charging and discharging is further facilitated. The average particle size of the negative electrode active material is, for example, the median diameter (D50) measured using a laser particle size distribution analyzer.

[0100] The negative electrode active material contained in the first negative electrode active material layer 22 includes, for example, one or more selected from a carbon-based negative electrode active material and a metal or semi-metal negative electrode active material.

[0101] The carbon-based negative electrode active material includes, for example, amorphous carbon, crystalline carbon, porous carbon, or a combination thereof.

[0102] The carbon-based negative electrode active material is particularly amorphous carbon. Examples of amorphous carbon include, but are not limited to, carbon black (CB), acetylene black (AB), furnace black (FB), ketjen black (KB), and graphene. Any amorphous carbon classified as amorphous carbon in the art can be used. Amorphous carbon is carbon that has no crystallinity or very low crystallinity and is distinguished from crystalline carbon or graphite-based carbon.

[0103] The carbon-based negative electrode active material may be, for example, porous carbon. The pore volume of 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 of 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 m 2 / g~3000m 2 The BET specific surface area of ​​the porous carbon can be measured, for example, according to ISO 9277:2022.

[0104] The metal or semimetal negative electrode active material may include, but is not limited to, one or more selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). Any metal or semimetal negative electrode active material known in the art that forms an alloy or compound with lithium may be used. For example, nickel (Ni) is not a metal negative electrode active material because it does not form an alloy with lithium.

[0105] The first negative electrode active material layer 22 may include one of these negative electrode active materials or a mixture of multiple different negative electrode active materials. For example, the first negative electrode active material layer 22 may include only amorphous carbon, or may include one or more selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). Alternatively, the first negative electrode active material layer 22 may include a mixture of amorphous carbon and one or more selected from the group consisting of gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). The mixing ratio of the mixture of amorphous carbon and gold or the like is, 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, but is not necessarily limited to such ranges and is selected depending on the required characteristics of the all-solid-state secondary battery 1. When the negative electrode active material has such a composition, the cycle characteristics of the all-solid-state secondary battery 1 are further improved.

[0106] The negative electrode active material contained in the first negative electrode active material layer 22 includes, for example, a mixture of first particles made of amorphous carbon and second particles made of a metal or semi-metal. The metal or semi-metal includes, for example, gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), and zinc (Zn). Alternatively, the semi-metal is a semiconductor. The content of the second particles is 1 to 99 wt %, 1 to 60 wt %, 8 to 60 wt %, 10 to 50 wt %, 15 to 40 wt %, or 20 to 30 wt %, based on the total weight of the mixture. When the content of the second particles is within such a range, for example, the cycle characteristics of the all-solid-state secondary battery 1 are further improved.

[0107] Alternatively, the first negative electrode active material layer 22 contains a composite negative electrode active material. The composite negative electrode active material includes, for example, a carbon-based support and a metal-based negative electrode active material supported on the carbon-based support. By having such a structure, the composite negative electrode active material prevents the uneven distribution of the metal-based negative electrode active material within the first negative electrode active material layer, and a uniform distribution is obtained. As a result, the cycle characteristics of the all-solid-state secondary battery 1 including the first negative electrode active material layer 22 are further improved.

[0108] The metal-based 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. The metal includes, for example, gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), tellurium (Te), and zinc (Zn). The metal oxide includes, for example, gold (Au) oxide, platinum (Pt) oxide, palladium (Pd) oxide, silicon (Si) oxide, silver (Ag) oxide, aluminum (Al) oxide, bismuth (Bi) oxide, tin (Sn) oxide, tellurium (Te) oxide, and zinc (Zn) oxide. The metal oxide includes, 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), Si x O y (0 < x ≤ 1, 0 < y ≤ 2), Ag x O y (0 < x ≤ 2, 0 < y ≤ 1), Al x O y (0 < x ≤ 2, 0 < y ≤ 3), Bi x O[[ID=3I]] y (0 < x ≤ 2, 0 < y ≤ 3), Sn x O[[ID=J5]] y (0 < x ≤ 1, 0 < y ≤ 2), Te x O y (0 < x ≤ 1, 0 < y ≤ 3), Zn x O y (0 < x ≤ 1, 0 < y ≤ 1) or a combination thereof. The composite of a metal and a metal oxide includes, for example, Au and Au x Oy A composite with (0 < x ≤ 2, 0 < y ≤ 3), Pt and Pt x O y A composite with (0 < x ≤ 1, 0 < y ≤ 2), Pd and Pd x O y A composite with (0 < x ≤ 1, 0 < y ≤ 1), Si and Si x O y A composite with (0 < x ≤ 1, 0 < y ≤ 2), Ag and Ag x O y A composite with (0 < x ≤ 2, 0 < y ≤ 1), Al and Al x O y A composite with (0 < x ≤ 2, 0 < y ≤ 3), Bi and Bi x O y A composite with (0 < x ≤ 2, 0 < y ≤ 3), Sn and Sn [[ID=二十六]] x O y A composite with (0 < x ≤ 1, 0 < y ≤ 2), Te and Te x O y A composite with (0 < x ≤ 1, 0 < y ≤ 3), Zn and Zn x O y It includes a composite with (0 < x ≤ 1, 0 < y ≤ 1) or a combination thereof.

[0109] The carbon-based support is, for example, amorphous carbon. Amorphous carbon is, for example, carbon black (CB), acetylene black (AB), furnace black (FB), ketjen black (KB), graphene, activated carbon, carbon nanofibers (CNF), carbon nanotubes (CNT), etc., but is not necessarily limited to them, and any material classified as amorphous carbon in the relevant technical field can be used. Amorphous carbon is carbon that has no crystallinity or very low crystallinity and is distinguished from crystalline carbon or graphite-based carbon. The carbonaceous material is, for example, a carbon-based negative electrode active material.

[0110] The composite negative electrode active material may be, for example, particulate. The particle size of the particulate composite negative electrode active material may be, for example, 10 nm to 4 μm, 10 nm to 1 μm, 10 nm to 500 nm, 10 nm to 200 nm, or 10 nm to 100 nm. When the composite negative electrode active material has a particle size within such a range, reversible absorption and / or desorption of lithium during charge and discharge is facilitated. The metal-based negative electrode active material supported on the support may be, for example, particulate. The particle size of the metal-based negative electrode active material may be, for example, 1 nm to 200 nm, 1 nm to 150 nm, 5 nm to 100 nm, or 10 nm to 50 nm. The carbon-based support may be, for example, particulate. The particle size of the carbon-based support may be, for example, 10 nm to 2 μm, 10 nm to 1 μm, 10 nm to 500 nm, 10 nm to 200 nm, or 10 nm to 100 nm. By having the carbon-based support have a particle size within such a range, it can be more uniformly distributed within the first negative electrode active material layer. The carbon-based support may also be, for example, nanoparticles with a particle size of 500 nm or less. The particle sizes of the composite negative electrode active material, the metal-based negative electrode active material, and 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 analyzer. Alternatively, the average particle size may be determined automatically using software from an electron microscope image, or may be determined manually and passively.

[0111] [Negative electrode layer: binder] Examples of the binder contained in the first negative electrode active material layer 22 include, but are not limited to, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, vinylidene fluoride / hexafluoropropylene copolymer, polyacrylonitrile, polymethyl methacrylate, etc. Any binder commonly used in the art may be used. The binder may be a single binder or a combination of multiple different binders.

[0112] The inclusion of a binder in the first negative electrode active material layer 22 stabilizes the first negative electrode active material layer 22 on the negative electrode current collector 21. Furthermore, cracking of the first negative electrode active material layer 22 is suppressed despite volume changes and / or relative position changes of the first negative electrode active material layer 22 during charge and discharge. For example, if the first negative electrode active material layer 22 does not include a binder, the first negative electrode active material layer 22 may easily separate from the negative electrode current collector 21. When the first negative electrode active material layer 22 separates from the negative electrode current collector 21, the negative electrode current collector 21 comes into contact with the solid electrolyte layer 30 at the exposed portion, increasing the possibility of a short circuit. The first negative electrode active material layer 22 is prepared, for example, by applying a slurry, in which materials constituting the first negative electrode active material layer 22 are dispersed, onto the negative electrode current collector 21 and drying the slurry. The negative electrode active material can be stably dispersed in the slurry by including a binder in the first negative electrode active material layer 22. For example, when the slurry is applied onto the negative electrode current collector 21 by a screen printing method, clogging of the screen (for example, clogging due to aggregates of the negative electrode active material) can be suppressed.

[0113] [Negative electrode layer: Other additives] 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, and ion-conducting auxiliary agents.

[0114] [Negative electrode layer: solid electrolyte] The first anode active material layer 22 may further include a solid electrolyte. The solid electrolyte may be, for example, a material selected from the solid electrolytes included in the solid electrolyte layer 30. The solid electrolyte included in the first anode active material layer 22 acts as a reaction site where lithium metal formation begins within the first anode active material layer 22, a space where the formed lithium metal is stored, or a path for transporting lithium ions. The solid electrolyte is optional.

[0115] In the first negative electrode active material layer 22, the content of the solid electrolyte is, for example, high in a region adjacent to the solid electrolyte layer 30 and low in a region adjacent to the negative electrode current collector 21. In the first negative electrode active material layer 22, the solid electrolyte may have a concentration gradient, for example, where the concentration decreases from the region adjacent to the solid electrolyte layer 30 to the region adjacent to the negative electrode current collector 21.

[0116] [Negative electrode layer: first negative electrode active material layer] The ratio (B / A) of the initial charge capacity (B) of the first negative electrode active material layer 22 to the initial charge capacity (A) of the positive electrode active material layer is 0.005 to 0.45. st open circuit voltage) to Li / Li + The initial charge capacity of the first negative electrode active material layer 22 is determined by charging the first negative electrode active material layer 22 to a maximum charging voltage (2 nd open circuit voltage) to Li / Li + It is determined by charging to 0.01V.

[0117] The maximum charging voltage is determined by the type of positive electrode active material. The maximum charging voltage may 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 a Li2S composite is Li / Li + For example, the maximum charging voltage of Li2S or Li2S composite is 2.5V for Li / Li + The ratio (B / A) of the initial charge capacity (B) of the first negative electrode active material layer 22 to the initial charge capacity (A) of the positive electrode active material layer is, for example, 0.01 to 0.3, 0.01 to 0.2, or 0.05 to 0.1.

[0118] The initial charge capacity (mAh) of the positive electrode active material layer 12 is obtained by multiplying the charge specific capacity (mAh / g) of the positive electrode active material by the mass (g) of the positive electrode active material in the positive electrode active material layer 12. When multiple types of positive electrode active materials are used, the charge capacity density x mass value is calculated for each positive electrode active material, and the sum of these values ​​is the initial charge capacity of the positive electrode active material layer 12. The initial charge capacity of the first negative electrode active material layer 22 is also calculated in a similar manner. The initial charge capacity of the first negative electrode active material layer 22 is obtained by multiplying the charge capacity density (mAh / g) of the negative electrode active material by the mass of the negative electrode active material in the first negative electrode active material layer 22. When multiple types of negative electrode active materials are used, the charge capacity density x mass value is calculated for each negative electrode active material, and the sum of these values ​​is the initial charge capacity of the first negative electrode active material layer 22. The charge capacity densities of the positive electrode active material and the negative electrode active material can be measured using an all-solid-state half-cell using lithium metal as a counter electrode. The initial charge capacities of the positive electrode active material layer 12 and the first negative electrode active material layer 22 are measured at a constant current density, for example, 0.1 mA / cm. 2 For the positive electrode, the measurement can be performed by measuring the first open circuit voltage (°C / V) to the maximum charging voltage, e.g., 3.0 V (vs. Li / Li + For the negative electrode, the measurements can be performed for an operating voltage from the second open circuit voltage (°C / V) to 0.01 V relative to the negative electrode, e.g., lithium metal. For example, an all-solid-state half-cell with a positive electrode active material layer can have a current of 0.1 mA / cm from the first open circuit voltage to 3.0 V. 2 The all-solid-state half-cell having the first negative electrode active material layer was charged at a constant current of 0.1 mA / cm from the second open circuit voltage to 0.01 V. 2 The current density during constant current charging is, for example, 0.2 mA / cm 2 , or 0.5mA / cm 2An all-solid-state half-cell having a positive electrode active material layer can be charged, for example, from the first open circuit voltage to 2.5 V, 2.0 V, 3.5 V, or 4.0 V. The maximum charging voltage of the positive electrode active material layer can be determined by the maximum voltage of a battery that satisfies the safety conditions specified in JIS C8712:2015 of the Japanese Standards Association.

[0119] If the initial charge capacity of the first anode active material layer 22 is excessively small, the thickness of the first anode active material layer 22 becomes very thin, and lithium dendrites formed between the first anode active material layer 22 and the anode current collector 21 during repeated charge and discharge processes collapse the first anode 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 anode 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 due to the first anode active material layer 22 increases, making it difficult to improve the cycle characteristics of the all-solid-state secondary battery 1.

[0120] The thickness of the first negative electrode active material layer 22 is, for example, 50% or less, 40% or less, 30% or less, 20% or less, 10% or less, or 5% or less of the thickness of the positive electrode active material layer 12. The thickness of the first negative electrode active material layer 22 is, for example, 1 to 50%, 1 to 40%, 1 to 30%, 1 to 20%, 1 to 10%, or 1 to 5% of the thickness of the positive electrode active material layer 12. The thickness of the first negative electrode active material layer 22 is, for example, 1 μm to 20 μm, 2 μm to 15 μm, or 3 μm to 10 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 will 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 increases excessively, the energy density of the all solid state secondary battery 1 decreases, the internal resistance of the all solid state secondary battery 1 due to the first negative electrode active material layer 22 increases, and it becomes 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.

[0121] [Negative electrode layer: second negative electrode active material layer] Although not shown, the all-solid-state secondary battery 1 further includes, for example, a second negative electrode active material layer disposed between the negative electrode current collector 21 and the first negative electrode active material layer 22 after charging. The second negative electrode active material layer is a metal layer containing lithium or a lithium alloy. The metal layer contains lithium or a lithium alloy. Therefore, since the second negative electrode active material layer is a metal layer containing lithium, it functions, for example, as a lithium reservoir. Examples of lithium alloys include, but are not limited to, Li-Al alloys, Li-Sn alloys, Li-In alloys, Li-Ag alloys, Li-Au alloys, Li-Zn alloys, Li-Ge alloys, and Li-Si alloys. Any lithium alloy commonly used in the art can be used. The second negative electrode active material layer may be composed of one of these alloys or lithium, or may be composed of multiple alloys. The second negative electrode active material layer may be, for example, a plated layer. The second negative electrode active material layer is 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, for example.

[0122] The thickness of the second negative electrode active material layer is not particularly limited, and may be, for example, 1 μm to 500 μm, 1 μm to 200 μm, 1 μm to 150 μm, 1 μm to 100 μm, or 1 μm to 50 μm. If the thickness of the second negative electrode active material layer is too thin, it may be difficult for the second negative electrode active material layer to function as a lithium reservoir. If the thickness of the second negative electrode active material layer is too thick, the mass and volume of the all-solid-state secondary battery 1 may increase, which may actually deteriorate the cycle characteristics of the all-solid-state secondary battery 1.

[0123] Furthermore, in the all solid state secondary battery 1, the second negative electrode active material layer may be disposed, for example, between the negative electrode current collector 21 and the first negative electrode active material layer 22 before assembling the all solid state secondary battery 1. When the second negative electrode active material layer 23 is disposed between the negative electrode current collector 21 and the first negative electrode active material layer 22 before assembling the all solid state secondary battery 1, the second negative electrode active material layer is a metal layer containing lithium and therefore acts as a lithium reservoir. For example, lithium foil may be disposed between the negative electrode current collector 21 and the first negative electrode active material layer 22 before assembling the all solid state secondary battery 1.

[0124] When the second anode active material layer is deposited by charging after the all-solid-state secondary battery 1 is assembled, the energy density of the all-solid-state secondary battery 1 increases because the all-solid-state secondary battery 1 does not include a second anode active material layer during assembly. When the all-solid-state secondary battery 1 is charged, it is charged beyond the charge capacity of the first anode active material layer 22. That is, the first anode active material layer 22 is overcharged. At the initial stage of charging, lithium is absorbed into the first anode active material layer 22. The anode active material contained in the first anode active material layer 22 forms an alloy or compound with lithium ions transferred from the positive electrode layer 10. When the first anode active material layer 22 is charged beyond its capacity, lithium is deposited on the back surface of the first anode active material layer 22, i.e., between the anode current collector 21 and the first anode active material layer 22, and the deposited lithium forms a metal layer corresponding to the second anode active material layer. The second anode active material layer is a metal layer mainly composed of lithium (i.e., metallic lithium). Such results can be achieved, for example, by the negative electrode active material contained in the first negative electrode active material layer 22 containing a material that forms an alloy or compound with lithium. During discharge, lithium in the first negative electrode active material layer 22 and the second negative electrode active material layer, i.e., the metal layer, is ionized and moves toward the positive electrode layer 10. This allows lithium to be used as the negative electrode active material in the all-solid-state secondary battery 1. Furthermore, since the first negative electrode active material layer 22 covers the second negative electrode active material layer, it serves as a protective layer for the second negative electrode active material layer, i.e., the metal layer, and also serves to suppress the precipitation and growth of lithium dendrites. This prevents short circuits and capacity reduction in the all-solid-state secondary battery 1, thereby improving the cycle characteristics of the all-solid-state secondary battery 1. Furthermore, after the all solid state secondary battery 1 is assembled, when the second negative electrode active material layer is disposed by charging, the negative electrode layer 20, i.e., the negative electrode current collector 21 and the first negative electrode active material layer 22, and the region therebetween are Li-free regions that do not contain lithium (Li) in the initial state or after full discharge of the all solid state secondary battery 1.

[0125] [Negative electrode layer: negative electrode current collector] The negative electrode current collectors 21, 21a, and 21b are made of a material that does not react with lithium, i.e., does not form any alloys or compounds with lithium. Materials constituting the negative electrode current collector 21 include, but are not limited to, copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), and nickel (Ni), and any material used as an electrode current collector in the art can be used. The negative electrode current collector 21 can be made of one of the above-mentioned metals, or 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.

[0126] Although not shown, the all-solid-state secondary battery 1 may further include a thin film containing an element that forms an alloy with lithium on one surface of the anode current collector 21. The thin film is disposed between the anode current collector 21 and the first anode active material layer 22. The thin film contains, for example, an element that forms an alloy with lithium. Examples of elements that form an alloy with lithium include, but are not limited to, gold, silver, zinc, tin, indium, silicon, aluminum, and bismuth. Any element known in the art to form an alloy with lithium can be used. The thin film may be made of one of these metals or an alloy of multiple metals. By disposing the thin film on one surface of the anode current collector 21, for example, the deposition morphology of the second anode active material layer deposited between the thin film 24 and the first anode active material layer 22 may be further flattened, thereby further improving the cycle characteristics of the all-solid-state secondary battery 1.

[0127] 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 is difficult for the thin film to exhibit its function. If the thin film is excessively thick, the thin film itself absorbs lithium, reducing the amount of lithium deposited at the negative electrode, reducing the energy density of the all-solid-state battery, and possibly deteriorating the cycle characteristics of the all-solid-state secondary battery 1. The thin film can be disposed on the negative electrode current collector 21 by, for example, vacuum deposition, sputtering, plating, or the like, but is not necessarily limited to such methods, and any method known in the art for forming a thin film can be used.

[0128] Although not shown, the negative electrode current collector 21 includes, 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 also 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 also be an insulating polymer. When the base film includes an insulating thermoplastic polymer, the base film softens or liquefies in the event of a short circuit, thereby shutting down 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 electrode current collector 21 may further include a metal piece and / or a lead tab. For more specific details about the base film, metal layer, metal piece, and lead tab of the negative electrode current collector 21, please refer to the above-mentioned positive electrode current collector 11. When the negative electrode current collector 21 has such a structure, the weight of the negative electrode can be reduced, and as a result, the energy density of the negative electrode and the lithium battery can be improved.

[0129] [Negative electrode layer: second inactive member] 6 to 9, the all-solid-state secondary batteries 1, 1a, and 1b further include second inactive members 50, 50a, 50b, and 50c disposed on the other surfaces of the negative electrode current collectors 21, 21a, and 21b.

[0130] The second inert member 50 further includes a conductive material, and is therefore electrically conductive, which distinguishes it from the first inert member 40. The second inert member 50 is, for example, a conductive flame-retardant inert member.

[0131] Examples of the conductive material include graphite, carbon black, acetylene black, Ketjen black, Denka black, carbon fiber, carbon nanotubes (CNT), graphene, metal fiber, metal powder, etc. The electronic conductivity of the second inert member 50 at 25°C is, for example, 100 times or more, 1000 times or more, or 10000 times or more than the electronic conductivity of the first inert member 40 at 25°C.

[0132] The second inactive member 50 includes, for example, a matrix, a filler, and a conductive material. The matrix includes, for example, a base material and a reinforcing material. The second inactive member 50 may further include a filler, a binder, etc. The content of the conductive material in the second inactive member 50 is, for example, 1 to 30 parts by weight, 1 to 20 parts by weight, 1 to 15 parts by weight, 1 to 10 parts by weight, 5 to 40 parts by weight, 5 to 30 parts by weight, or 5 to 35 parts by weight per 100 parts by weight of the second inactive member 50.

[0133] The Young's modulus of the second inactive member 50 is, for example, smaller than that of the negative electrode current collector 21. The Young's modulus of the second inactive member 50 is, for example, 50% or less, 30% or less, 10% or less, or 5% or less of that of the negative electrode current collector 21. The Young's modulus of the second inactive member 50 is, for example, 0.01% to 50%, 0.1% to 30%, 0.1 to 10%, or 1 to 5% of that of the negative electrode current collector 21. The Young's modulus of the second inactive member 50 is, for example, 100 MPa or less, 50 MPa or less, 30 MPa or less, 10 MPa or less, or 5 MPa or less. The Young's modulus of the second inactive member 50 is, for example, 0.01 to 100 MPa, 0.1 to 50 MPa, 0.1 to 30 MPa, 0.1 to 10 MPa, or 1 to 5 MPa.

[0134] The second inactive members 50, 50a, and 50b are conductive and can therefore function as the negative electrode current collector 21. In addition, the second inactive members 50, 50a, and 50b have a lower Young's modulus than the negative electrode current collector 50, and can therefore more effectively accommodate the volume change of the negative electrode layer 20 during charging and discharging of the all-solid-state secondary battery 1. As a result, the second inactive members 50, 50a, and 50b can effectively relieve internal stress caused by the volume change of the all-solid-state secondary battery 1 during charging and discharging of the all-solid-state secondary battery 1, thereby improving the cycle characteristics of the all-solid-state secondary battery 1.

[0135] The thickness of the second inactive member 50 is, for example, greater than the thickness of the first negative electrode active material layer 22. The second inactive member 50 has a greater thickness than the first negative electrode active material layer 22, which can more effectively accommodate volume changes in the negative electrode layer 20 during charge and discharge. The thickness of the first negative electrode active material layer 22 is 50% or less, 40% or less, 30% or less, 20% or less, or 10% or less of the thickness of the second inactive member 50. 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 second inactive member 50. The thickness of the second inactive member 50 is, for example, 1 μm to 300 μm, 10 μm to 300 μm, 50 μm to 300 μm, or 100 μm to 200 μm. If the thickness of the second inactive member 50 is excessively thin, it is difficult to achieve the intended effect, and if the thickness of the second inactive member 50 is excessively thick, the energy density of the all-solid-state secondary battery 1 may be reduced. The shape of the second inactive member 50 is not particularly limited and may be selected depending on the shape of the all-solid-state secondary battery 1. The second inactive member 50 may be, for example, in the shape of a sheet, a rod, or a gasket.

[0136] The second inactive member 50 may be disposed, for example, on one or both surfaces of one all-solid-state secondary battery 1. The second inactive member 50 may be disposed, for example, between a plurality of stacked all-solid-state secondary batteries 1. The second inactive member 50 may be disposed, for example, between each of a plurality of stacked all-solid-state secondary batteries 1, on the top surface and / or the bottom surface.

[0137] The ratio of the volume of the all solid state secondary battery 1 before charging to the volume of the all solid state secondary battery 1 after charging, or the volume expansion rate, is, for example, 15% or less, 10% or less, or 5% or less.

[0138] The increase in volume of the negative electrode layer 20 during charging of the all-solid-state secondary battery 1 is offset by the decrease in volume of the positive electrode layer 10, and the second inactive member 50 accommodates the volume change of the negative electrode layer 20, thereby mitigating the volume change of the all-solid-state secondary battery 1 before and after charging.

[0139] The energy density per unit volume of the all solid state secondary battery 1 is, for example, 500 to 900 Wh / L, 500 to 800 Wh / L, or 500 to 700 Wh / L. The energy density per unit weight of the all solid state secondary battery 1 is, for example, 350 to 600 Wh / g, 350 to 580 Wh / g, 350 to 570 Wh / g, or 350 to 550 Wh / g. When the all solid state secondary battery 1 has an energy density in such a range, it can provide an improved energy density compared to conventional secondary batteries.

[0140] [Solid electrolyte layer] [Solid electrolyte layer: solid electrolyte] 1-5, the solid electrolyte layer 30 includes an electrolyte disposed between the positive electrode layer 10 and the negative electrode layer 20. The electrolyte may include, for example, a solid electrolyte, a gel electrolyte, or a combination thereof.

[0141] The solid electrolyte may include, for example, a sulfide-based solid electrolyte, an oxide-based solid electrolyte, a polymer solid electrolyte, or a combination thereof.

[0142] The solid electrolyte is, for example, a sulfide-based solid electrolyte. Examples of the sulfide-based solid electrolyte include Li2S-P2S5, Li2S-P2S5-LiX (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, and Li2S-P2S5-Z. m S n (m and n are positive numbers, Z is one of Ge, Zn, or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (p and q are positive numbers, M is one of P, Si, Ge, B, Al, Ga, and In), Li 7-x PS 6-x Cl x (0≦x≦2), Li 7-x PS6-x Br x (0≦x≦2) and Li 7-x PS 6-x I x (0≦x≦2). The sulfide-based solid electrolyte is prepared by processing starting materials such as Li2S and P2S5 by a melt quenching method or a mechanical milling method. After such processing, a heat treatment can be performed. The solid electrolyte can be amorphous, crystalline, or a mixture thereof. The solid electrolyte can also contain, for example, sulfur (S), phosphorus (P), and lithium (Li) as constituent elements of the sulfide-based solid electrolyte material. For example, the solid electrolyte can be a material containing Li2S-P2S5. When a sulfide-based solid electrolyte material containing Li2S-P2S5 is used to form the solid electrolyte, the mixing molar ratio of Li2S to P2S5 is, for example, in the range of Li2S:P2S5=20:80 to 90:10, 25:75 to 90:10, 30:70 to 70:30, or 40:60 to 60:40.

[0143] The sulfide-based solid electrolyte may include, for example, an argyrodite-type solid electrolyte represented by the following Chemical Formula 1:

[0144] [Chemical formula 1] Li + 12-n-x A n+ X 2- 6-x Y - x

[0145] In the formula, A is P, As, Ge, Ga, Sb, Si, Sn, Al, In, Ti, V, Nb, or Ta, X is S, Se, or Te, and Y is Cl, Br, I, F, CN, OCN, SCN, or N3, where 1≦n≦5 and 0≦x≦2. 7-x PS 6-x Cl x (0≦x≦2), Li 7-x PS 6-x Brx (0≦x≦2) and Li 7-x PS 6-x I x (0≦x≦2). The sulfide-based solid electrolyte is also an argyrodite-type compound containing one or more selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I, for example.

[0146] The density of the argyrodite-type solid electrolyte is 1.5 to 2.0 g / cc. When the argyrodite-type solid electrolyte has a density of 1.5 g / cc or more, 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.

[0147] The oxide-based solid electrolyte is, 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)、Li 1+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 yTiO3(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. The oxide-based solid electrolyte is produced, for example, by a sintering method or the like.

[0148] The oxide-based solid electrolyte is, 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) is a garnet-type solid electrolyte selected therefrom.

[0149] The polymer solid electrolyte may include, for example, a mixture of a lithium salt and a polymer, or may include a polymer having an ion-conducting functional group. The polymer solid electrolyte may also be, for example, a polymer electrolyte that is in a solid state at 25°C and 1 atm. The polymer solid electrolyte does not include, for example, a liquid. The polymer solid electrolyte includes a polymer, and the polymer may be, 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, or the like. Polyvinyl fluoride (PSS), polymethyl methacrylate (PMMA), polyethylene glycol (PEG), polyacrylonitrile (PAN), polytetrafluoroethylene (PTFE), polyethylenedioxythiophene (PEDOT), polypyrrole (PPY), polyacrylonitrile (PAN), polyaniline, polyacetylene, Nafion, Aquivion, Flemion, Gore, Aciplex, Morgane ADP ADP), sulfonated poly(ether ether ketone) (SPEEK), sulfonated poly(arylene ether ketone ketone sulfone) (SPAEKKS), sulfonated poly(aryl ether ketone) (SPAEK), poly[bis(benzimidazobenzisoquinolinone)] (SPBIBI), polystyrene sulfonate (PSS), lithium 9,10-diphenylanthracene-2-sulfonate (DPASLi +) or a combination thereof, but is not limited thereto, and any lithium salt used as a polymer electrolyte in the art can be used. Any lithium salt used as a lithium salt in the art can be used. 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 SO2) (x and y are each 1 to 20), LiCl, LiI, or a mixture thereof. The polymer contained in the polymer solid electrolyte is, 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 contained in the polymer solid electrolyte is, for example, 1,000 Dalton or more, 10,000 Dalton or more, 100,000 Dalton or more, or 1,000,000 Dalton or more.

[0150] The gel electrolyte includes, for example, a polymer gel electrolyte, which may be, for example, polymer-free and in a gel state.

[0151] The polymer gel electrolyte may include, for example, a liquid electrolyte and a polymer, or may include an organic solvent and a polymer having an ion-conducting functional group. The polymer gel electrolyte may be, for example, a polymer electrolyte that is in a gel state at 25°C and 1 atm. The polymer gel electrolyte may be, for example, a liquid-free gel state. The liquid electrolyte used in the polymer gel electrolyte may be, for example, 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. The lithium salt may be selected from the lithium salts used in solid polymer electrolytes. An ionic liquid has a melting point below room temperature, is composed only of ions, and refers to a salt that is in a liquid state at room temperature or a room-temperature molten salt. The ionic liquid may, for example, comprise: 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 -and one or more anions selected from the group consisting of: a polymer solid electrolyte, a polymer gel electrolyte, and a compound containing ... solid electrolyte, a polymer gel electrolyte, and a compound containing one or more anions selected from the group consisting of: a polymer solid electrolyte, a polymer solid electrolyte, a polymer solid electrolyte, a polymer solid electrolyte, a polymer solid electrolyte, a polymer solid electrolyte, a polymer solid electrolyte, a polymer solid electrolyte, a polymer solid electrolyte, a polymer solid electrolyte, a polymer solid

[0152] The solid electrolyte layer 30 is also impermeable to lithium polysulfide. Therefore, it can block a side reaction between the lithium polysulfide generated during charging and discharging of the sulfide-based positive electrode active material and the negative electrode layer. As a result, the cycle characteristics of the all-solid-state secondary battery 1 including the solid electrolyte layer 30 can be improved.

[0153] [Solid electrolyte layer: binder] The solid electrolyte layer 30 may include, for example, a binder. Examples of binders included in the solid electrolyte layer 30 include, but are not limited to, styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, and polyethylene. Any binder used in the art may be used. The binder in the solid electrolyte layer 30 may be the same as or different from the binders included in the positive electrode active material layer 12 and the negative electrode active material layer 22. The binder may be omitted.

[0154] The binder content of 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% relative to the total weight of the solid electrolyte layer 30.

[0155] The present invention will be described in more detail below through examples and comparative examples, but the examples are intended to illustrate the present invention and are not intended to limit the scope of the present invention.

[0156] Example 1: Mono-cell all-solid-state secondary battery, sulfide-based positive electrode active material (Li 2 S-CNF composite), flame retardant first inert member (Production of negative electrode layer) A 10 μm thick stainless steel foil was prepared as the negative electrode current collector, and carbon black (CB) particles with a primary particle size of approximately 30 nm and silver (Ag) particles with an average particle diameter of approximately 60 nm were prepared as the negative electrode active material.

[0157] A mixed powder of 4g of carbon black (CB) and silver (Ag) particles mixed at a weight ratio of 3:1 was placed in a container, and 4g of NMP solution containing 7wt% PVDF binder (Kureha #9300) was added to prepare a mixed solution. Next, NMP was gradually added to the mixed solution while stirring the mixed solution to prepare a slurry. The prepared slurry was applied to a SUS sheet 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 then subjected to a pressure of 5 ton f / cm. 2 The surface of the first negative electrode active material layer of the laminate was flattened by cold roll pressing at a pressure of 1000 kJ / cm2 and a speed of 5 m / sec. The negative electrode layer was fabricated through the above process. The thickness of the first negative electrode active material layer included in the negative electrode layer was approximately 15 μm. The area of ​​the first negative electrode active material layer and the negative electrode current collector were the same. The initial charge capacity of the negative electrode was measured using the half-cell described above. The initial charge capacity of the first negative electrode active material layer was 2.3 mAh.

[0158] (Production of positive electrode layer) A Li2S-CNF composite was prepared as the positive electrode active material. The Li2S-CNF composite was fabricated according to the method disclosed in Electrochimica Acta 230 (2017) 279-284, except that vapor-grown carbon fiber (VGCF) was replaced with carbon nanofiber (CNF). Argyrodite-type crystal Li6PS5Cl (D50 = 3.0 μm, crystalline) was prepared as the solid electrolyte. Ketjen black was prepared as the conductive agent. These materials were mixed in a weight ratio of positive electrode active material: solid electrolyte: conductive agent = 40:50:10 to prepare a positive electrode mixture. The positive electrode mixture was obtained by dry mixing using a ball mill. The positive electrode mixture obtained by ball milling formed an ionic and electronic conductive network. The initial charge capacity of the positive electrode was measured using the half-cell described above. The initial charge capacity of the positive electrode active material layer was 25 mAh. In Example 1 The ratio (B / A) of the initial charge capacity (B) of the first negative electrode active material layer to the initial charge capacity (A) of the positive electrode active material layer is 0.09. The initial charge capacity of the positive electrode active material layer is calculated from the first open circuit voltage by Li / Li + The initial charge capacity of the first negative electrode active material layer was determined by charging to 2.8 V vs. Li / Li from the second open circuit voltage. + 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 were determined by charging to 0.01 V vs. V. In Examples 2 to 8 and Comparative Example 1, the ratios (B / A) of the initial charge capacity (B) of the first negative electrode active material layer to the initial charge capacity (A) of the positive electrode active material layer, measured under the same conditions as in Example 1, were 0.07 to 0.09. In Examples 7 and 8, double-sided positive electrodes were used, and therefore half of the initial positive electrode charge capacity was used in calculating the ratio (B / A).

[0159] The positive electrode mixture was placed on one side of a positive electrode current collector made of aluminum foil or SUS with a carbon coating on one side, and plate pressed at a pressure of 200 MPa for 10 minutes to produce a positive electrode layer. The thickness of the positive electrode layer was approximately 120 μm. The thickness of the positive electrode active material layer was approximately 100 μm, and the thickness of the carbon-coated aluminum foil was approximately 20 μm. The areas of the positive electrode active material layer and the positive electrode current collector were the same.

[0160] (Manufacturing of solid electrolyte layer) A mixture was prepared by adding 1.5 parts by weight of an acrylic binder to 98.5 parts by weight of an argyrodite-type crystal Li6PS5Cl solid electrolyte (D50 = 3.0 (m, crystalline)). Octyl acetate was added to the mixture while stirring to prepare a slurry. The prepared slurry was applied using a bar coater to a 15 μm-thick nonwoven fabric placed on a 75 μm-thick PET substrate, and dried in air at 80°C for 10 minutes to obtain a laminate. The obtained laminate was then vacuum-dried at 80°C for 2 hours. A solid electrolyte layer was prepared by the above process.

[0161] (Flame-retardant inert material) A slurry made by mixing pulp fiber, glass fiber, aluminum hydroxide (Al(OH)3), an acrylic binder, and a solvent was formed into a gasket shape, and the solvent was then removed to produce a flame-retardant inert member.

[0162] The weight ratio of cellulose fiber, glass fiber, aluminum hydroxide (Al(OH)3), and acrylic binder was 20:8:70:2. The thickness of the inert member was 120 μm.

[0163] Before the manufactured flame-retardant inert member was placed on the solid electrolyte layer, it was vacuum heat-treated at 80° C. for 5 hours to remove moisture and the like from the flame-retardant inert member.

[0164] (Manufacturing of all-solid-state secondary batteries) Referring to FIG. 1, a solid electrolyte layer was disposed on the anode layer such that the first anode active material layer was in contact with the solid electrolyte layer, and a cathode layer was disposed on the solid electrolyte layer. A gasket was disposed around the cathode layer, surrounding the cathode layer and in contact with the solid electrolyte layer, to fabricate a laminate. The gasket had a thickness of approximately 120 μm. A flame-retardant inert material was used as the gasket. The gasket was disposed so as to contact the side of the cathode layer and the solid electrolyte layer. The cathode layer was disposed at the center of the solid electrolyte layer, and the gasket surrounded the cathode layer and extended to the end of the solid electrolyte layer. The area of ​​the cathode layer was approximately 90% of the area of ​​the solid electrolyte layer, and a gasket was disposed over the entire remaining 10% of the area of ​​the solid electrolyte layer where the cathode layer was not disposed.

[0165] The prepared laminate was plate-pressed at 85°C and 500 MPa for 30 minutes. This pressurization sinters the solid electrolyte layer, improving battery performance. The thickness of the sintered solid electrolyte layer was approximately 45 μm. The density of the Li6PS5Cl solid electrolyte, an argyrodite-type crystal, contained in the sintered solid electrolyte layer was 1.6 g / cc. The area of ​​the solid electrolyte layer was the same as that of the negative electrode layer.

[0166] The pressed stack was placed in a pouch and vacuum-sealed to fabricate an all-solid-state secondary battery. Portions of the positive electrode current collector and the negative electrode current collector were extended to the outside of the sealed battery to serve as positive electrode terminals and negative electrode terminals.

[0167] Example 2: Sulfide-based positive electrode active material (Li 2 S-CNF composite), flame-retardant first inert material, conductive flame-retardant second inert material An all-solid-state secondary battery was manufactured in the same manner as in Example 1, except that before the pressed stack was placed in a pouch, a sheet-like conductive flame-retardant member having the same area and shape as the stack was additionally placed on the negative electrode current collector of the pressed stack and vacuum-sealed to manufacture an all-solid-state secondary battery. The conductive flame-retardant inert member sheet was prepared as follows. The conductive flame-retardant inert member sheet can act as an elastic sheet.

[0168] (Conductive flame-retardant inert material) A flame-retardant inert member was manufactured by forming a slurry of pulp fiber, glass fiber, aluminum hydroxide (Al(OH)3), acrylic binder, conductive material (Denka Black), and a solvent into a sheet and drying it. The weight ratio of the pulp fiber, glass fiber, aluminum hydroxide (Al(OH)3), acrylic binder, and conductive material was 20:8:50:2:20. The thickness of the conductive flame-retardant inert member was 120 μm. The manufactured conductive flame-retardant inert member was vacuum heat-treated at 80°C for 5 hours before being placed on the negative electrode current collector to remove moisture and other impurities from the conductive flame-retardant inert member.

[0169] Example 3: Sulfide-based positive electrode active material (Li 2 S-CNF composite), non-flame retardant first inert material An all-solid-state secondary battery was manufactured in the same manner as in Example 1, except that the flame-retardant inert member was changed to a non-flame-retardant inert member.

[0170] The non-flame retardant inert member contained pulp fiber and acrylic binder in a weight ratio of 98:2, and did not contain glass fiber or Al(OH)3. The thickness of the non-flame retardant inert member was 120 μm.

[0171] Example 4: Sulfide-based positive electrode active material (Li 2 SC-Li 6 PS 5 Cl complex), flame-retardant primary inert material An all-solid-state secondary battery was manufactured in the same manner as in Example 1, except that a Li2S-C-Li6PS5Cl composite was used as the positive electrode active material instead of the Li2S-VGCF composite.

[0172] The Li2S-C-Li6PS5Cl composite was prepared by the method disclosed in Nano Lett. 2016, 16, 7, 4521-4527.

[0173] Example 5: Sulfide-based positive electrode active material (LiS-C composite), first negative electrode active material layer (Ag-supported carbon), first flame-retardant inert member, and second conductive flame-retardant inert member An all-solid-state secondary battery was manufactured in the same manner as in Example 2, except that the following silver particle-supported carbon black was used as the negative electrode active material instead of the mixture of carbon black and silver particles.

[0174] (Production of carbon black carrying silver particles) Carbon black was dispersed in a 1.0 M sulfuric acid solution, stirred for 2 hours, filtered, and dried to prepare acid-treated carbon black.

[0175] A mixed solution was prepared by adding 10 g of acid-treated carbon black to a mixed solvent of 1500 g of distilled water, 1500 g of ethanol, and 30 g of glycerol and stirring. Then, 2 g of AgNO3 was added and stirred. The particle size of the carbon black was 80 nm. A reducing agent was added to the mixed solution to reduce and support silver ions on the carbon black. The carbon black supported with silver-containing particles was filtered, washed, and dried to prepare a composite anode active material. Scanning electron microscope and XPS analysis confirmed that multiple silver-containing particles were supported on the carbon black particles. The silver-containing particles were silver particles, silver oxide (Ag2O) particles, and composite particles of silver (Ag) and silver oxide (Ag2O). The silver-containing particle content of the composite anode active material was 5 wt%. The average particle size of the silver particles was 10 nm.

[0176] Example 6: Sulfide-based positive electrode active material (LiS-C-LiI composite), flame-retardant first inert member An all-solid-state secondary battery was manufactured in the same manner as in Example 1, except that a Li2S-C-LiI composite was used instead of the Li2S-VGCF composite as the positive electrode active material.

[0177] The Li2S-C-LiI composite was prepared by the method disclosed in Nano Lett. 2016, 16, 7, 4521-4527, except that Li6PS5Cl was replaced with LiI.

[0178] Comparative example 1: Sulfide-based positive electrode active material, no inert material used (free) An all-solid-state secondary battery was manufactured in the same manner as in Example 1, except that no flame-retardant inert member (ie, gasket) was used during the manufacture of the all-solid-state secondary battery.

[0179] Comparative Example 2: Oxide-based positive electrode active material, flame-retardant first inert member An all-solid-state secondary battery was produced in the same manner as in Example 1, except that a positive electrode containing a lithium transition metal oxide was used instead of a positive electrode containing a Li2S positive electrode active material. In Comparative Example 2 The ratio (B / A) of the initial charge capacity (B) of the first negative electrode active material layer to the initial charge capacity (A) of the positive electrode active material layer is 0.09. The initial charge capacity of the positive electrode active material layer is calculated from the first open circuit voltage by Li / Li + The initial charge capacity of the first negative electrode active material layer was determined by charging to 4.25 with respect to the second open circuit voltage. + The capacitance was determined by charging to 0.01 V.

[0180] A positive electrode containing a lithium transition metal oxide was prepared in the following manner.

[0181] (Production of positive electrode layer) Li2O-ZrO2 (LZO) coated LiNi as the positive electrode active material 0.8 Co 0.15 Al 0.05O2 (NCA) was prepared. The LZO-coated cathode active material was prepared according to the method disclosed in Korean Patent Publication No. 10-2016-0064942. Argyrodite-type crystal Li6PS5Cl (D50 = 0.5 μm, crystalline) was prepared as the solid electrolyte. Polytetrafluoroethylene (PTFE) binder (DuPont's Teflon binder) was prepared as the binder. Carbon nanofibers (CNF) were prepared as the conductive agent. These materials were mixed with xylene solvent in a weight ratio of 84:11.5:3:1.5 cathode active material:solid electrolyte:conductive agent:binder. The mixture was formed into a sheet and vacuum-dried at 40°C for 8 hours to prepare a cathode sheet. The cathode sheet was placed on one side of a cathode current collector made of aluminum foil coated on one side and plate-pressed at 200 MPa for 10 minutes to prepare a cathode layer. The thickness of the positive electrode layer was approximately 120 μm. The thickness of the positive electrode active material layer was approximately 100 μm, and the thickness of the carbon-coated aluminum foil was approximately 20 μm. The area of ​​the positive electrode active material layer and the positive electrode current collector were the same.

[0182] Example 7: One bi-cell all-solid-state secondary battery, sulfide-based positive electrode active material (Li 2 S-CNF composite), flame-retardant primary inert material (Manufacturing bi-cell all-solid-state secondary batteries) The positive electrode layer was prepared in the same manner as in Example 1, except that the positive electrode active material layers were arranged on both sides of the positive electrode current collector.

[0183] The total thickness of the positive electrode layer was about 220 μm, the thickness of each positive electrode active material layer was about 100 μm, and the thickness of the carbon-coated aluminum foil was about 20 μm.

[0184] Two negative electrode layers, two solid electrolyte layers, and two flame-retardant inert members were prepared in the same manner as in Example 1.

[0185] Referring to Figure 3, a solid electrolyte layer was disposed on the negative electrode layer so that the first negative electrode active material layer was in contact with the solid electrolyte layer, and a positive electrode layer was disposed on the solid electrolyte layer. The positive electrode layer had a structure in which a positive electrode active material layer was disposed on each side of a positive electrode current collector. A gasket was disposed around the positive electrode layer, surrounding the positive electrode layer and in contact with the solid electrolyte layer. The gasket had a thickness of approximately 220 μm. The gasket was, for example, a structure in which two 110 μm-thick gaskets were stacked, or a single 220 μm-thick gasket. A flame-retardant inert material was used as the gasket.

[0186] The gasket was placed so as to contact the side of the positive electrode layer and the solid electrolyte layer. The positive electrode layer was placed at the center of the solid electrolyte layer, and the gasket surrounded the positive electrode layer and extended to the end of the solid electrolyte layer. The area of ​​the positive electrode layer was approximately 90% of the area of ​​the solid electrolyte layer, and the gasket was placed over the remaining 10% of the area of ​​the solid electrolyte layer where the positive electrode layer was not placed. A stack was produced by placing the solid electrolyte layer on the positive electrode layer and the gasket, and then placing the negative electrode layer on the solid electrolyte layer.

[0187] The prepared laminate was plate-pressed at 85°C and a pressure of 500 MPa for 30 minutes. This pressurization sinters the solid electrolyte layer, improving battery performance. The thickness of one sintered solid electrolyte layer was approximately 45 μm. The density of the Li6PS5Cl solid electrolyte, an argyrodite-type crystal contained in the sintered solid electrolyte layer, was 1.6 g / cc. The area of ​​the solid electrolyte layer was the same as that of the negative electrode layer.

[0188] The pressurized laminate was placed in a pouch and vacuum-sealed to produce an all-solid-state secondary battery. Portions of the positive electrode current collector and the negative electrode current collector were extended to the outside of the sealed battery to serve as positive electrode layer terminals and negative electrode layer terminals.

[0189] Example 8: Sulfide-based positive electrode active material (Li 2 S-CNF composite), flame-retardant first inert material, conductive flame-retardant second inert material An all-solid-state secondary battery was manufactured in the same manner as in Example 7, except that before the pressed laminate was placed in a pouch, sheet-like conductive flame-retardant inert members having the same area and shape as the laminate were additionally placed on one side of the pressed laminate and the other side opposite the one side, and then vacuum-sealed to manufacture an all-solid-state secondary battery. The conductive flame-retardant inert members were prepared in the same manner as in Example 2.

[0190] Evaluation example 1: Calculation of volume change rate during charging of all-solid-state secondary batteries [Al current collector (10 μm) / LiNi 0.8 Co 0.15 Al 0.05 The volume change of the first all-solid-state secondary battery during charging was calculated from the initial first volume of the first all-solid-state secondary battery having a structure of O2(NCA) positive electrode active material layer (100 μm) / Li6PS5Cl solid electrolyte layer (32 μm) / first negative electrode active material layer (7 μm) / SUS current collector (10 μm) and the second volume after charging of the first all-solid-state secondary battery in which a 30 μm-thick lithium metal layer was deposited between the first negative electrode active material layer and the SUS current collector upon charging, and is shown in Table 1 below. It was assumed that there was no change in the thickness of the NCA positive electrode active material layer before and after charging.

[0191] The volume change of the second all-solid-state secondary battery during charging was calculated from the initial volume 1 of the second all-solid-state secondary battery with a structure of [Al current collector (10 μm) / LiS (60 wt%)-carbon (40 wt%) positive electrode active material layer (50 μm) / LiPS5Cl solid electrolyte layer (32 μm) / first negative electrode active material layer (7 μm) / SUS current collector (10 μm)] and the volume 2 of the second all-solid-state secondary battery after charging, in which a 30 μm-thick lithium metal layer was deposited between the first negative electrode active material layer and the SUS current collector upon charging. The volume change was calculated and is shown in Table 1 below. It was assumed that the thickness of the LiS (60 wt%)-carbon (40 wt%) structure after charging decreased by 15 μm from 50 μm to 35 μm. It was assumed that all lithium contained in the LiS migrated to the negative electrode. The positive electrode active material layer of the second all-solid-state secondary battery was assumed to consist only of LiS and carbon. The positive electrode active material layer of the first all-solid-state secondary battery was assumed to be made of NCA.

[0192] [Table 1]

[0193] As shown in Table 1, in the second all-solid-state secondary battery having a positive electrode active material layer containing Li2S, the volume of the negative electrode layer increased due to the deposition of the lithium metal layer, but the volume of the positive electrode active material layer decreased, thereby suppressing the increase in the volume of the all-solid-state secondary battery as a whole. In contrast, in the first all-solid-state secondary battery having a positive electrode active material layer containing a lithium transition metal oxide, the volume change of the positive electrode active material layer was slight, and therefore the increase in the volume of the all-solid-state secondary battery as a whole due to the deposition of the lithium metal layer was significant.

[0194] Therefore, it was confirmed that the second all-solid-state secondary battery effectively prevents deterioration such as cracking of the all-solid-state secondary battery by mitigating the volume change that occurs during charging and discharging of the all-solid-state secondary battery due to the first all-solid-state secondary battery.

[0195] Evaluation example 2: Charge / discharge test The charge-discharge characteristics of the all-solid-state secondary batteries prepared in Examples 1 to 8 and Comparative Example 1 were evaluated by the following charge-discharge test. The charge-discharge test was carried out by placing the all-solid-state secondary batteries in a thermostatic chamber at 45°C.

[0196] In the first cycle, the battery was charged at a constant current of 0.1 C for 12.5 hours until the battery voltage reached 2.5 V to 2.8 V. Then, the battery was discharged at a constant current of 0.1 C for 12.5 hours until the battery voltage reached 0.5 V.

[0197] In the second cycle, the battery was charged at a constant current of 0.33 C for 12.5 hours until the battery voltage reached 2.5 V to 2.8 V. Then, the battery was discharged at a constant current of 0.33 C for 12.5 hours until the battery voltage reached 0.5 V.

[0198] In the third cycle, the battery was charged at a constant current of 1.0 C for 12.5 hours until the battery voltage reached 2.5 V to 2.8 V. Then, the battery was discharged at a constant current of 1.0 C for 12.5 hours until the battery voltage reached 0.5 V.

[0199] The charge-discharge characteristics of the all-solid-state secondary battery prepared in Comparative Example 2 were evaluated by the following charge-discharge test. The charge-discharge test was carried out by placing the all-solid-state secondary battery in a thermostatic chamber at 45°C.

[0200] In the first cycle, the battery was charged at a constant current of 0.1 C for 12.5 hours until the battery voltage reached 3.9 V to 4.25 V. Then, the battery was discharged at a constant current of 0.1 C for 12.5 hours until the battery voltage reached 2.5 V.

[0201] In the second cycle, the battery was charged at a constant current of 0.33 C for 12.5 hours until the battery voltage reached 3.9 V to 4.25 V. Then, the battery was discharged at a constant current of 0.33 C for 12.5 hours until the battery voltage reached 2.5 V.

[0202] In the third cycle, the battery was charged at a constant current of 1.0 C for 12.5 hours until the battery voltage reached 3.9 V to 4.25 V. Then, the battery was discharged at a constant current of 1.0 C for 12.5 hours until the battery voltage reached 2.5 V.

[0203] The presence or absence of short circuits during the charge / discharge process up to the third cycle, the initial discharge capacity, and the high-rate characteristics are shown in Table 2 below.

[0204] The presence or absence of a short circuit is indicated by an O if the short circuit occurs before the first cycle is completed, a △ if the short circuit occurs in the second cycle, and an X if the short circuit does not occur until the third cycle is completed.

[0205] [Table 2]

[0206] As shown in Table 2, the all-solid-state secondary batteries of Examples 1 to 8 exhibited improved cycle characteristics compared to the all-solid-state secondary battery of Comparative Example 1.

[0207] Evaluation example 3: High temperature life characteristic test The charge-discharge characteristics of the all-solid-state secondary batteries prepared in Examples 1 to 8 and Comparative Example 1 were evaluated by the following charge-discharge test. The charge-discharge test was carried out by placing the all-solid-state secondary batteries in a thermostatic chamber at 45°C.

[0208] The first cycle is 0.6mA / cm until the battery voltage reaches 2.5V to 2.8V. 2 The battery was charged at a constant current of 0.6 mA / cm for 12.5 hours until the battery voltage reached 0.5 V. 2 The battery was discharged at a constant current of 1000 kJ / s for 12.5 hours.

[0209] The charge-discharge characteristics of the all-solid-state secondary battery prepared in Comparative Example 2 were evaluated by the following charge-discharge test. The charge-discharge test was carried out by placing the all-solid-state secondary battery in a thermostatic chamber at 45°C.

[0210] The first cycle was 0.6 mA / cm until the battery voltage reached 3.9 V to 4.25 V. 2 The battery was charged at a constant current of 0.6 mA / cm for 12.5 hours until the battery voltage reached 2.5 V. 2 The battery was discharged at a constant current of 1000 kJ / s for 12.5 hours.

[0211] The discharge capacity of the first cycle was taken as the standard capacity. After the second cycle, charging and discharging were repeated up to 150 cycles under the same conditions as the first cycle. The measurement results are shown in Table 3 below.

[0212] The more cycles required for the discharge capacity to decrease to 95% of the standard capacity after the second cycle, the better the life characteristics were considered to be.

[0213] In the all-solid-state secondary battery of Comparative Example 1, a short circuit occurred before the first cycle was completed, making it impossible to measure the life characteristics.

[0214] [Table 3]

[0215] As shown in Table 3, the all solid state secondary batteries of Examples 1 to 8 had improved life characteristics compared to the all solid state secondary battery of Comparative Example 2.

[0216] The all-solid-state secondary battery of Example 6 contained a Li2S-C-LiI composite as a positive electrode active material, and thus had further improved life characteristics compared to Example 1 containing a Li2S-C composite and Example 4 containing a Li2S-C-Li6PS5Cl composite.

[0217] The all-solid-state secondary batteries of Examples 1 to 6 containing LiS were determined to have improved life characteristics due to less volume change during charge and discharge compared to the all-solid-state secondary battery of Comparative Example 2 containing an oxide-based positive electrode active material.

[0218] The all-solid-state secondary batteries of Examples 7 and 8, which have a bi-cell structure in which the components are symmetrically arranged, were determined to have improved life characteristics by effectively mitigating volume changes during charge and discharge compared to the all-solid-state secondary batteries of Examples 1 to 4, which have a mono-cell structure.

[0219] It was determined that the all-solid-state secondary batteries of Examples 1, 2 and 4, which contained a flame-retardant inert member, had improved life characteristics compared to Example 3, which contained a non-flame-retardant inert member.

[0220] The all-solid-state secondary battery of Example 8 was determined to have improved life characteristics compared to the all-solid-state secondary battery of Example 7 because the second inactive member was additionally disposed on the negative electrode current collector, thereby effectively alleviating stress in the negative electrode layer where volume change is concentrated. For the same reason, the all-solid-state secondary battery of Example 2 was also determined to have improved life characteristics compared to Examples 1, 3, and 4. The all-solid-state secondary battery of Example 5 was determined to have improved life characteristics compared to Example 2, which is a simple mixture of silver particles and carbon particles, by using carbon carrying silver particles.

[0221] As described above, the all-solid-state secondary battery according to this embodiment can be applied to various portable devices, vehicles, and the like.

[0222] Although an exemplary embodiment has been described in detail above with reference to the accompanying drawings, the present invention is not limited to such an example. It is obvious that a person skilled in the art to which the present invention pertains can derive various modifications or alterations within the scope of the technical idea described in the claims, and it goes without saying that these also fall within the technical scope of the present invention. [Explanation of symbols]

[0223] 1 All-solid-state secondary battery 10 Positive electrode layer 11 Positive electrode current collector 12 Cathode active material layer 20 negative electrode layer 21 Negative electrode current collector 22 First negative electrode active material layer 30 Solid electrolyte layer 40 First inert member 50 Second inert member

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; the positive electrode layer includes a positive electrode current collector and a positive electrode active material layer disposed on one or both surfaces of the positive electrode current collector, The positive electrode active material layer contains a lithium-containing sulfide-based positive electrode active material, and the lithium-containing sulfide-based positive electrode active material contains Li ２ S., Li. ２ S-containing complexes or combinations thereof, a first inactive member disposed on one side of both the positive electrode current collector and the positive electrode active material layer, the negative electrode layer includes a negative electrode current collector and a first negative electrode active material layer disposed on one surface of the negative electrode current collector, a ratio (B / A) of an initial charge capacity (B) of the first negative electrode active material layer to an initial charge capacity (A) of the positive electrode active material layer is 0.005 to 0.45; The initial charge capacity of the positive electrode active material layer is calculated from the first open circuit voltage as follows: Li / Li ＋ is determined by charging to the maximum charging voltage, The initial charge capacity of the first negative electrode active material layer is calculated from the second open circuit voltage as follows: Li / Li ＋ An all-solid-state secondary battery as determined by charging to 0.01 V with respect to the

2. The Li ２ The S-containing complex is Li ２ S and carbon complex, Li ２ A composite of S, carbon, and a solid electrolyte, Li ２ S and solid electrolyte composite, Li ２ A composite of S, carbon, and a lithium salt, Li ２ A complex of S and a lithium salt, Li ２ S and metal carbide complex, Li ２ S, carbon and metal carbide composite, Li ２ S and metal nitride complex, Li ２ The all-solid-state secondary battery according to claim 1 , comprising a composite of S, carbon, and a metal nitride, or a combination thereof.

3. The positive electrode active material layer is FeS ２ , V.S. ２ , NaS, MnS, FeS, NiS, CuS, or a combination thereof.

4. the positive electrode active material layer further includes at least one selected from the group consisting of a solid electrolyte, a conductive material, and a binder; 2. The all-solid-state secondary battery according to claim 1, wherein the solid electrolyte comprises a sulfide-based solid electrolyte, and the conductive material comprises a carbon-based conductive material.

5. the first inactive member surrounds a side surface of the positive electrode layer and is in contact with the solid electrolyte layer; the first inactive member extends from one side of the positive electrode layer along a surface of the solid electrolyte layer to an end portion of the solid electrolyte layer; the area of ​​the positive electrode layer is smaller than the area of ​​the solid electrolyte layer in contact with the positive electrode layer, The all-solid-state secondary battery according to claim 1 , wherein the first inactive member surrounds a side surface of the positive electrode layer and compensates for an area difference between the positive electrode layer and the solid electrolyte layer.

6. the thickness of the first inactive member is greater than the thickness of the first negative electrode active material layer; the thickness of the first negative electrode active material layer is 50% or less of the thickness of the first inactive member, The all-solid-state secondary battery according to claim 1 , wherein no negative electrode active material layer is present on the other surface of the negative electrode current collector.

7. the positive electrode layer includes a positive electrode current collector and a first positive electrode active material layer and a second positive electrode active material layer disposed on both surfaces of the positive electrode current collector, respectively; the solid electrolyte layer includes a first solid electrolyte layer and a second solid electrolyte layer in contact with the first positive electrode active material layer and the second positive electrode active material layer, respectively; the anode layer includes a first anode layer and a second anode layer in contact with the first solid electrolyte layer and the second solid electrolyte layer, respectively; 2. The all-solid-state secondary battery according to claim 1, wherein the first inactive member is disposed between the first solid electrolyte layer and the second solid electrolyte layer facing each other, surrounding a side surface of the positive electrode layer.

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

9. the matrix comprises a substrate and a reinforcing material; the substrate includes a first fibrous material, the first fibrous material is an insulating material, and the first fibrous material includes one or more selected from pulp fibers, insulating polymer fibers, and ion-conductive polymer fibers; the reinforcing material includes a second fibrous material, the second fibrous material is a flame retardant material, and the second fibrous material includes one or more selected from glass fibers and ceramic fibers; the filler is a moisture adsorbent, and the filler comprises a metal hydroxide; The metal hydroxide is Mg(OH). ２ , Fe(OH) ３ , Sb(OH) ３ , Sn(OH) ４ , TI(OH) ３ , Zr(OH) ４ , and Al(OH) ３ The all-solid-state secondary battery according to claim 8 , comprising one or more selected from the following:

10. the first negative electrode active material layer includes a negative electrode active material and a binder, 2. The all-solid-state secondary battery according to claim 1, wherein the negative electrode active material is in a particulate form, and the average particle size of the negative electrode active material is 4 μm or less.

11. the negative electrode active material includes at least one selected from the group consisting of a carbon-based negative electrode active material and a metal or semi-metal negative electrode active material, The carbon-based negative electrode active material includes amorphous carbon, crystalline carbon, porous carbon, or a combination thereof; 11. The all-solid-state secondary battery according to claim 10, wherein the metal or semi-metal negative electrode active material comprises gold (Au), platinum (Pt), palladium (Pd), silicon (Si), silver (Ag), aluminum (Al), bismuth (Bi), tin (Sn), zinc (Zn), or a combination thereof.

12. the negative electrode active material includes a mixture of first particles made of amorphous carbon and second particles made of a metal or a metalloid, The all-solid-state secondary battery of claim 10, wherein the content of the second particles is 1 to 60 wt % based on the total weight of the mixture.

13. The all-solid-state secondary battery according to claim 1 , wherein the first negative electrode active material layer further comprises a solid electrolyte.

14. the negative electrode active material includes a carbon-based support and a metal-based negative electrode active material supported on the carbon-based support, the metal-based negative electrode active material comprises a metal, a metal oxide, a composite of a metal and a metal oxide, or a combination thereof; the metal-based negative electrode active material is particulate, and the particle size of the metal-based negative electrode active material is 1 nm to 200 nm; the carbon-based support has a particulate shape, the particle size of the carbon-based support is 10 nm to 2 μm, and the all-solid-state secondary battery further includes a second negative electrode active material layer disposed between the negative electrode current collector and the first negative electrode active material layer after being charged; The all-solid-state secondary battery according to claim 10 , wherein the second negative electrode active material layer is a metal layer, and the metal layer contains lithium or a lithium alloy.

15. The negative electrode further includes a second inactive member disposed on the other surface of the negative electrode current collector, 2. The all-solid-state secondary battery according to claim 1, wherein the second inactive member comprises a conductive flame-retardant inactive member.

16. the Young's modulus of the second inactive member is smaller than the Young's modulus of the negative electrode current collector; the second inactive member has a Young's modulus of 100 MPa or less; the thickness of the second inactive member is greater than the thickness of the first negative electrode active material layer; 16. The all-solid-state secondary battery according to claim 15, wherein the thickness of the first negative electrode active material layer is 50% or less of the thickness of the second inactive member.

17. the volume expansion rate of the all-solid-state secondary battery after charging is 15% or less, 2. The all-solid-state secondary battery according to claim 1, wherein the energy density of the all-solid-state secondary battery is 500 to 900 Wh / L or 350 to 600 Wh / kg.

18. the solid electrolyte layer includes an electrolyte; the electrolyte comprises a solid electrolyte, a gel electrolyte, or a combination thereof; the solid electrolyte comprises a sulfide-based solid electrolyte, an oxide-based solid electrolyte, a polymer solid electrolyte, or a combination thereof; the gel electrolyte comprises a polymer gel electrolyte, 2. The all-solid-state secondary battery according to claim 1, wherein the solid electrolyte layer is impermeable to lithium polysulfide.

19. The sulfide-based solid electrolyte is Li ２ S-P ２ S ５ , Li ２ S-P ２ S ５ -LiX (X is a halogen element), Li ２ S-P ２ S ５ -Li ２ O, Li ２ S-P ２ S ５ -Li ２ O-LiI, Li ２ S-SiS ２ , Li ２ S-SiS ２ - LiI, Li ２ S-SiS ２ - LiBr, Li ２ S-SiS ２ -LiCl, Li ２ S-SiS ２ -B ２ S ３ - LiI, Li ２ S-SiS ２ -P ２ S ５ - LiI, Li ２ S-B ２ S ３ , Li ２ S-P ２ S ５ -Z ｍ S ｎ (m and n are positive numbers, Z is one of Ge, Zn, and Ga), Li ２ S-GeS ２ , Li ２ S-SiS ２ -Li ３ P.O. ４ , Li ２ S-SiS ２ -Li ｐ MO ｑ (p and q are positive numbers, M is one of P, Si, Ge, B, Al, and GaIn), Li ７－ｘ P.S. ６－ｘ Cl ｘ (0≦x≦2), Li ７－ｘ P.S. ６－ｘ Br ｘ (0≦x≦2) and Li ７－ｘ P.S. ６－ｘ I ｘ (0≦x≦)2, The sulfide-based solid electrolyte is Li ６ P.S. ５ Cl, Li ６ P.S. ５ Br and Li ６ P.S. ５ an argyrodite-type solid electrolyte containing one or more selected from I, 19. The all-solid-state secondary battery according to claim 18, wherein the density of the argyrodite-type solid electrolyte is 1.5 to 2.0 g / cc.

20. At least one of the positive electrode current collector and the negative electrode current collector includes a base film and a metal layer disposed on one or both sides of the base film, the base film comprises a polymer, the polymer comprising polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polybutylene terephthalate (PBT), polyimide (PI), or a combination thereof; 2. The all-solid-state secondary battery according to claim 1, 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), lithium (Li), or an alloy thereof.

Images