All-solid battery and battery module

Abstract

To provide an all-solid battery with a rate characteristic improved.SOLUTION: An all-solid battery 10 includes a positive electrode including a positive electrode active material layer 1, a solid electrolyte layer 5 including a solid electrolyte particle (A), and a negative electrode including a negative electrode active material layer 2 in this order. The positive electrode active material layer 1 and the solid electrolyte layer 5 are in contact with each other. When the contact length is L1 and the length of the straight line is L2 at an interface between the positive electrode active material layer 1 and the solid electrolyte layer 5 that is measured by the following method, the ratio (L1 / L2) of L1 to L2 is 1.1 or more and 1.4 or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] An all-solid-state battery includes, for example, a positive electrode active material layer, a solid electrolyte layer, and a negative electrode active material layer in this order. Patent Document 1 describes a technique relating to all-solid-state batteries.

[0003] Patent Document 1 aims to provide, through the development of a manufacturing technology for all-solid-state secondary batteries, an all-solid-state secondary battery that exhibits good ion conductivity and effectively improves resistance to peeling between the active material layer and the inorganic solid electrolyte layer. The all-solid-state secondary battery has a positive electrode active material layer, a negative electrode active material layer, and an inorganic solid electrolyte layer interposed between the two layers, wherein the inorganic solid electrolyte layer contains an ion-conductive inorganic solid electrolyte, and the maximum height roughness Rz of at least one of the interfaces between the positive electrode active material layer and the inorganic solid electrolyte layer or the interface between the negative electrode active material layer and the inorganic solid electrolyte layer is 1.5 μm to 5 μm. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-195183 Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention provides an all-solid-state battery with improved cycle characteristics. [Means for solving the problem]

[0006] According to the present invention, the following all-solid-state battery and battery module are provided.

[0007] [1] a positive electrode including a positive electrode active material layer; a solid electrolyte layer containing a solid electrolyte (A); a negative electrode including a negative electrode active material layer; in this order, the positive electrode active material layer and the solid electrolyte layer are in contact with each other, An all-solid-state battery, wherein, when a contact length at an interface between the positive electrode active material layer and the solid electrolyte layer is defined as L1 and a linear length at the interface between the positive electrode active material layer and the solid electrolyte layer is defined as L2, the ratio of L1 to L2 (L1 / L2) measured by the following method is 1.1 or more and 1.4 or less. (method) A cross section of the cathode active material layer and the solid electrolyte layer is photographed at a magnification of 2000x using a scanning electron microscope (SEM), with the stacking direction of the cathode active material layer and the solid electrolyte layer being the vertical direction, so that the interface between the cathode active material layer and the solid electrolyte layer includes at least 60 μm in the horizontal direction. From the obtained cross-sectional SEM image, the linear length and contact length of the interface between the cathode active material layer and the solid electrolyte layer are measured using image analysis software. The contact length is the length of the contact surface obtained by sampling contact points between the cathode active material and the solid electrolyte in a 60 μm horizontal section in the cross-sectional SEM image and connecting each contact point with a straight line. The linear length is the length of the line obtained by connecting the two ends of the contact points sampled when measuring the contact length with a straight line and projecting the line onto a horizontal plane. [2] The all-solid-state battery according to [1], wherein the solid electrolyte (A) comprises one or more selected from the group consisting of sulfide-based solid electrolytes, oxide-based solid electrolytes, and polymer electrolytes. [3] The all-solid-state battery according to [1] or [2], wherein the content of the solid electrolyte (A) in the solid electrolyte layer is 50.0 parts by mass or more and 100.0 parts by mass or less, when the total amount of the solid electrolyte layer is 100.0 parts by mass. [4] The all-solid-state battery according to any one of [1] to [3], wherein the positive electrode active material layer contains, as a positive electrode active material, a lithium composite oxide having a layered rock salt crystal structure. [5] The all-solid-state battery according to [4], wherein the lithium composite oxide comprises one or more selected from the group consisting of lithium-nickel composite oxide, lithium-cobalt composite oxide, lithium-nickel-aluminum composite oxide, and lithium-nickel-cobalt-manganese composite oxide. [6] The all-solid-state battery according to [5], wherein the lithium composite oxide contains a lithium-nickel-cobalt-manganese composite oxide. [7] The all-solid-state battery according to any one of [1] to [6], wherein the negative electrode active material layer contains one or more negative electrode active materials selected from the group consisting of carbon materials, lithium-based metal materials, Si-based materials, and conductive polymer materials. [8] A battery module comprising the all-solid-state battery according to any one of [1] to [7]. [Effects of the Invention]

[0008] According to the present invention, an all-solid-state battery with improved cycle characteristics can be provided. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a cross-sectional view showing an example of the structure of an all-solid-state battery according to an embodiment of the present invention. [Figure 2] 3 is a top view of the interface α between the solid electrolyte layer and the positive electrode active material layer of the present embodiment, illustrating the measurement site of the contact length L1 and the linear length L2 at the interface α. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] The following describes an embodiment of the present invention. Note that the shapes, sizes, and layouts of the various components in the drawings are merely schematic representations that allow the present invention to be understood, and are not to scale. Furthermore, unless otherwise specified, "to" in a numerical range indicates a range from above to below.

[0011] <All-solid-state battery> FIG. 1 is a cross-sectional view showing an example of the structure of an all-solid-state battery 10 of this embodiment. The all-solid-state battery 10 of this embodiment includes, in this order, a positive electrode including a positive electrode active material layer 1, a solid electrolyte layer 5 including a solid electrolyte (A), and a negative electrode including a negative electrode active material layer 2, and the positive electrode active material layer 1 and the solid electrolyte layer 5 are in contact with each other. When the contact length of the interface between the positive electrode active material layer 1 and the solid electrolyte layer 5 is L1 and the linear length is L2, the ratio of L1 to L2 (L1 / L2) is 1.1 or more and 1.4 or less, as measured by the following method. From the viewpoint of further improving the cycle characteristics of the all-solid-state battery, the (L1 / L2) ratio is preferably 1.2 or more and 1.4 or less, more preferably 1.3 or more and 1.4 or less, and even more preferably 1.3. The (L1 / L2) ratio can be adjusted by, for example, adjusting the conditions for compressing the electrode laminate precursor in the step of producing an all-solid-state battery, the type and blending ratio of the positive electrode active material in the positive electrode active material layer, the type and blending ratio of the solid electrolyte in the solid electrolyte layer, etc. In particular, in order to set the (L1 / L2) ratio within the above range, the conditions for compressing the electrode laminate precursor in the step of producing an all-solid-state battery are important.

[0012] In this embodiment, the contact length L1 and the linear length L2 in the cross section of the interface between the positive electrode active material layer and the solid electrolyte layer can be measured by obtaining a cross-sectional SEM image using a scanning electron microscope (SEM) in the following manner, and then using image analysis software from the obtained cross-sectional SEM image. (Method) A cross-section of the cathode active material layer and the solid electrolyte layer is photographed at a magnification of 2000x using a scanning electron microscope (SEM), with the direction in which the cathode active material layer and the solid electrolyte layer are stacked vertically, so that the interface between the cathode active material layer and the solid electrolyte layer includes at least 60 μm in the horizontal direction. From the obtained cross-sectional SEM image, the linear length and contact length of the interface between the cathode active material layer and the solid electrolyte layer are measured using image analysis software (e.g., Image J (National Institutes of Health)). The contact length is the length of the contact surface obtained by sampling contact points between the cathode active material and the solid electrolyte in a 60 μm section in the horizontal direction in the cross-sectional SEM image and connecting each contact point with a straight line. The linear length is the length of the line obtained by connecting the two ends of the contact points sampled when measuring the contact length with a straight line and projecting the line onto a horizontal plane.

[0013] As a result of investigations by the present inventors, it was found that there is a correlation between the ratio (L1 / L2) of the contact length L1 to the linear length L2 at the interface between the positive electrode active material layer and the solid electrolyte layer and the cycle characteristics of the all-solid-state battery. As a result of further intensive investigations based on the above findings, the present inventors found that the cycle characteristics of the all-solid-state battery can be improved by setting L1 / L2 within the above range, and completed the present invention. The reason why the cycle characteristics of the all-solid-state battery can be improved when L1 / L2 is within the above range is not clear, but it is speculated that the mechanism is that when L1 / L2 is within the above range, the contact area between the positive electrode active material and the solid electrolyte falls within an appropriate range, thereby improving the cycle characteristics of the all-solid-state battery.

[0014] Here, the contact length L1 and the linear length L2 of the interface between the solid electrolyte layer and the positive electrode active material layer in the all-solid-state battery of this embodiment will be described. Contact length L1 refers to the length of the contact surface obtained by horizontally sampling contact points between the positive electrode active material and the solid electrolyte at the interface between the solid electrolyte layer and the positive electrode active material layer in a cross-sectional SEM image taken using a scanning electron microscope (SEM) and connecting each contact point with a straight line, and means the actual length of the interface between the positive electrode active material layer 1 and the solid electrolyte layer 5. Straight-line length L2 refers to the length of a projected line when contact length L1 at the interface between the positive electrode active material layer 1 and the solid electrolyte layer 5 is projected onto a horizontal plane.

[0015] Here, the measurement site of the ratio (L1 / L2) of the contact length L1 to the linear length L2 at the interface α between the positive electrode active material layer and the solid electrolyte layer will be described with reference to Fig. 2. Fig. 2 is a top view of the interface α for explaining the measurement site of the contact length L1 and the linear length L2 at the interface α between the solid electrolyte layer and the positive electrode active material layer of this embodiment. Select a center line b1 that passes through the center O of the interface α between the positive electrode active material layer 1 and the solid electrolyte layer 5, select lines b2 and b3 that are parallel to the center line b1, select a center line b4 that is perpendicular to the center line b1, and select lines b5 and b6 that are parallel to the center line b4. The perpendicular distances d1 to d4 between the lines are, for example, 5 mm or more and 20 mm or less. Next, select region a1 centered on the intersection of center line b1 and center line b4, select region a2 centered on the intersection of center line b1 and line b5, select region a3 centered on the intersection of center line b1 and line b6, select region a4 centered on the intersection of line b2 and center line b4, select region a5 centered on the intersection of line b2 and line b5, select region a6 centered on the intersection of line b2 and line b6, select region a7 centered on the intersection of line b3 and center line b4, select region a8 centered on the intersection of line b3 and line b5, and select region a9 centered on the intersection of line b3 and line b6. Next, cross sections are prepared in the regions a1 to a9, and cross-sectional SEM images are taken using a scanning electron microscope (SEM), to obtain contact lengths L1 in the regions a1 to a9. Next, the straight line length L2 in the regions a1 to a9 is calculated. For example, the straight line length L2 in the regions a1 to a9 can be calculated from the length of one side of the regions a1 to a9. Next, the ratio of the average value of the contact length L1 in the regions a1 to a9 to the average value of the linear length L2 in the regions a1 to a9 (average value of the contact length L1 in the regions a1 to a9 / average value of the linear length L2 in the regions a1 to a9) is determined, and this is defined as the ratio (L1 / L2) of the contact length L1 to the linear length L2 at the interface α between the positive electrode active material layer 1 and the solid electrolyte layer 5.

[0016] The scanning electron microscope (SEM) may be, for example, an SU1500 manufactured by Hitachi High-Technologies Corporation. The magnification during measurement is, for example, 2000 times.

[0017] (solid electrolyte layer) The solid electrolyte layer of this embodiment contains a solid electrolyte (A).

[0018] The solid electrolyte (A) of the present embodiment preferably contains one or more selected from the group consisting of sulfide-based solid electrolytes, oxide-based solid electrolytes, and polymer electrolytes, from the viewpoint of further improving the cycle characteristics of the all-solid-state battery.

[0019] Examples of sulfide-based solid electrolytes include Li2S-P2S5 materials, Li2S-SiS2 materials, Li2S-GeS2 materials, Li2S-Al2S3 materials, Li2S-SiS2-Li3PO4 materials, Li2S-P2S5-GeS2 materials, Li2S-Li2O-P2S5-SiS2 materials, Li2S-GeS2-P2S5-SiS2 materials, Li2S-SnS2-P2S5-SiS2 materials, Li2S-P2S5-Li3N materials, and Li2S 2+X-P4S3 material, Li2S-P2S5-P4S3 material, LiPO4-Li2S-SiS material, Li3PS4, Li3PO4-Li2S-Si2S material, Li3PO4-Li2S-SiS2 material, LiI-L i2S-B2S3 material, LiI-Li2S-SiS2 material, LiI-Li2S-P2S5 material, LiI-Li2S-P2O5 material, LiI-Li3PO4-P2S5Li2S-P2S5-LiCl material, Li 7-x PS 6-x Cl x (where 0≦x≦2), Li 7-x PS 6-x Br x (where 0≦x≦2), Li 7-x PS 6-x I x (where 0≦x≦2), Li 10 GeP2S 12 , and Li 3.25 Ge 0.25 P 0.75 S4, more preferably Li 7-x PS 6-x Cl x (where 0≦x≦2), Li 7-x PS 6-x Br x (where 0≦x≦2) and Li 7-x PS 6-x I x (where 0≦x≦2), more preferably contains one or more selected from the group consisting of Li6PS5Cl, Li6PS5Br and Li6PS5I, and even more preferably contains Li6PS5Cl.

[0020] Examples of oxide-based solid electrolytes include NASICON-type solid electrolyte materials such as LiTi2(PO4)3, LiZr2(PO4)3, and LiGe2(PO4)3; 0.5+x Li 0.5-3x ) Perovskite-type solid electrolyte materials such as TiO3; one or more selected from the group consisting of Li2O-P2O5 materials, Li2O-P2O5-Li3N materials, etc.

[0021] The polymer-based solid electrolyte material includes one or more selected from the group consisting of polyether-based electrolyte materials such as polyethylene oxide, polypropylene oxide, ethylene oxide-propylene copolymer, and dimethylsiloxane-ethylene oxide copolymer; gel polymer electrolyte materials such as polyacrylonitrile, polyvinylidene fluoride, and vinylidene fluoride-hexafluoropropylene polymer; and polymer solid electrolyte materials using hyperbranched polymers.

[0022] The average particle size d of the solid electrolyte (A) in the volume-based particle size distribution measured by the laser diffraction scattering particle size distribution measurement method 50 From the viewpoint of further improving the cycle characteristics of the all-solid-state battery, the thickness is preferably 0.5 μm or more and 30.0 μm or less, more preferably 1.0 μm or more and 20.0 μm or less, even more preferably 3.0 μm or more and 15.0 μm or less, even more preferably 4.0 μm or more and 10.0 μm or less, even more preferably 4.5 μm or more and 9.0 μm or less, even more preferably 5.0 μm or more and 8.0 μm or less, and even more preferably 5.5 μm or more and 7.0 μm or less.

[0023] When the entire solid electrolyte layer is taken as 100.0 parts by mass, the content of the solid electrolyte (A) in the solid electrolyte layer of the present embodiment is, from the viewpoint of further improving the cycle characteristics of the all-solid-state battery, preferably 50.0 parts by mass or more and 100.0 parts by mass or less, more preferably 60.0 parts by mass or more and 99.9 parts by mass or less, even more preferably 70.0 parts by mass or more and 99.5 parts by mass or less, even more preferably 85.0 parts by mass or more and 99.5 parts by mass or less, even more preferably 90.0 parts by mass or more and 99.0 parts by mass or less, even more preferably 93.0 parts by mass or more and 98.0 parts by mass or less, even more preferably 93.5 parts by mass or more and 97.5 parts by mass or less, and even more preferably 94.0 parts by mass or more and 97.0 parts by mass or less.

[0024] The solid electrolyte layer of the present embodiment may contain a binder resin. The binder resin for the solid electrolyte layer of this embodiment preferably contains one or more selected from the group consisting of fluorine-based binder resins, rubber-based binder resins, and acrylic binder resins. Such binder resins may be in the form of an emulsion. When water is used as the solvent, it is preferable to use an aqueous binder resin in combination with a thickener such as CMC (carboxymethyl cellulose).

[0025] When the entire solid electrolyte layer is taken as 100 parts by mass, the content of the binder resin in the solid electrolyte layer of the present embodiment is, from the viewpoint of further improving the cycle characteristics of the all-solid-state battery, preferably 0.5 parts by mass or more and 15.0 parts by mass or less, more preferably 1.0 parts by mass or more and 10.0 parts by mass or less, even more preferably 1.5 parts by mass or more and 8.0 parts by mass or less, even more preferably 2.0 parts by mass or more and 7.0 parts by mass or less, even more preferably 2.5 parts by mass or more and 6.5 parts by mass or less, and even more preferably 3.0 parts by mass or more and 6.0 parts by mass or less.

[0026] The thickness of the solid electrolyte layer of this embodiment is preferably 1 μm or more and 150 μm or less, more preferably 5 μm or more and 100 μm or less, and even more preferably 10 μm or more and 80 μm or less.

[0027] The solid electrolyte layer of this embodiment can be formed on the surface of a negative electrode by, for example, applying a slurry of a solid electrolyte dispersed in an organic solvent to the surface of a negative electrode active material layer formed on a negative electrode current collector, followed by drying. The organic solvent may include, for example, one or more selected from the group consisting of acetonitrile, xylene, dimethoxyethane, dimethyl carbonate, triethylamine, and other tertiary amine solvents, heptane, hexane, tetrahydrofuran, toluene, N-methylpyrrolidone, as well as ether solvents, thiol solvents, and butyl butyrate, and it is preferable that all of the organic solvents have been dehydrated.

[0028] (positive electrode) The positive electrode of this embodiment includes a positive electrode active material layer. The positive electrode active material layer of this embodiment contains, for example, a positive electrode active material, and may further contain one or more selected from the group consisting of a positive electrode binder resin, a solid electrolyte, and a conductive additive.

[0029] The positive electrode active material of the present embodiment is not particularly limited, and examples thereof include composite oxides of lithium and transition metals such as lithium-nickel composite oxide, lithium-cobalt composite oxide, lithium-manganese composite oxide, lithium-nickel-manganese composite oxide, lithium-nickel-cobalt composite oxide, lithium-nickel-aluminum composite oxide, lithium-nickel-cobalt-aluminum composite oxide, lithium-nickel-cobalt-manganese composite oxide, lithium-nickel-manganese-aluminum composite oxide, and lithium-nickel-cobalt-manganese-aluminum composite oxide; transition metal sulfides such as TiS, FeS, and MoS; MnO, VO, and VO. 13 and TiO2, and olivine-type lithium phosphate oxides. From the viewpoint of improving the working potential, capacity, durability, and energy density, the composite oxide preferably contains a lithium composite oxide having a layered rock-salt crystal structure, more preferably contains one or two or more selected from the group consisting of lithium-nickel composite oxide, lithium-cobalt composite oxide, lithium-nickel-aluminum composite oxide, and lithium-nickel-cobalt-manganese composite oxide, and even more preferably contains lithium-nickel-cobalt-manganese composite oxide. Here, the olivine-type lithium phosphate contains, for example, at least one element selected from the group consisting of Mn, Cr, Co, Cu, Ni, V, Mo, Ti, Zn, Al, Ga, Mg, B, Nb, and Fe, as well as lithium, phosphorus, and oxygen.

[0030] The average particle diameter d of the positive electrode active material of this embodiment 50 is preferably 0.1 μm or more and 30 μm or less, more preferably 0.3 μm or more and 20 μm or less, even more preferably 0.5 μm or more and 15 μm or less, and even more preferably 1.0 μm or more and 10.0 μm or less. 50means the particle size at 50% cumulative value in the particle size distribution (volume basis) determined by the laser diffraction scattering method.

[0031] When the entire cathode active material layer is taken as 100.0 parts by mass, from the viewpoint of further improving the cycle characteristics of the all-solid-state battery, the content of the cathode active material in the cathode active material layer of this embodiment is preferably 50.0 parts by mass or more and 90.0 parts by mass or less, more preferably 55.0 parts by mass or more and 90.0 parts by mass or less, even more preferably 60.0 parts by mass or more and 90.0 parts by mass or less, even more preferably 65.0 parts by mass or more and 90.0 parts by mass or less, even more preferably 70.0 parts by mass or more and 88.0 parts by mass or less, and even more preferably 75.0 parts by mass or more and 85.0 parts by mass or less.

[0032] The positive electrode active material layer of this embodiment may contain one or more binder resins selected from the group consisting of fluorine-based binder resins, rubber-based binder resins, and acrylic binder resins. Such binder resins may be in the form of an emulsion. When water is used as the solvent, it is preferable to use an aqueous binder resin in combination with a thickener such as CMC (carboxymethyl cellulose).

[0033] The content of the positive electrode binder resin in the positive electrode active material layer of this embodiment is preferably 0.5 parts by mass or more and 8.0 parts by mass or less, more preferably 0.8 parts by mass or more and 7.5 parts by mass or less, even more preferably 1.0 parts by mass or more and 7.0 parts by mass or less, and still more preferably 1.5 parts by mass or more and 6.5 parts by mass or less, when the entire positive electrode active material layer is taken as 100 parts by mass, from the viewpoint of further improving the cycle characteristics of the all-solid-state battery.

[0034] The solid electrolyte in the positive electrode active material layer of the present embodiment preferably includes one or more selected from the group consisting of a sulfide-based solid electrolyte, an oxide-based solid electrolyte, and a polymer electrolyte, and more preferably includes a sulfide-based solid electrolyte.

[0035] Examples of oxide-based solid electrolytes include NASICON-type solid electrolyte materials such as LiTi2(PO4)3, LiZr2(PO4)3, and LiGe2(PO4)3;0.5+x Li 0.5-3x ) Perovskite-type solid electrolyte materials such as TiO3; one or more selected from the group consisting of Li2O-P2O5 materials, Li2O-P2O5-Li3N materials, etc.

[0036] Examples of sulfide-based solid electrolytes include Li2S-P2S5 materials, Li2S-SiS2 materials, Li2S-GeS2 materials, Li2S-Al2S3 materials, Li2S-SiS2-Li3PO4 materials, Li2S-P2S5-GeS2 materials, Li2S-Li2O-P2S5-SiS2 materials, Li2S-GeS2-P2S5-SiS2 materials, Li2S-SnS2-P2S5-SiS2 materials, Li2S-P2S5-Li3N materials, and Li2S 2+X -P4S3 material, Li2S-P2S5-P4S3 material, LiPO4-Li2S-SiS material, Li3PS4, Li3PO4-Li2S-Si2S material, Li3PO4-Li2S-SiS2 material, LiI-L i2S-B2S3 material, LiI-Li2S-SiS2 material, LiI-Li2S-P2S5 material, LiI-Li2S-P2O5 material, LiI-Li3PO4-P2S5Li2S-P2S5-LiCl material, Li 7-x PS 6-x Cl x (where 0≦x≦2), Li 7-x PS 6-x Br x (where 0≦x≦2), Li 7-x PS 6-x I x (where 0≦x≦2), Li 10 GeP2S 12 , and Li 3.25 Ge 0.25 P 0.75 S4, more preferably Li 7-x PS 6-x Cl x (where 0≦x≦2), Li 7-x PS 6-x Br x (where 0≦x≦2) and Li 7-x PS 6-x I x(where 0≦x≦2), more preferably contains one or more selected from the group consisting of Li6PS5Cl, Li6PS5Br and Li6PS5I, and even more preferably contains Li6PS5Cl.

[0037] The polymer-based solid electrolyte material includes one or more selected from the group consisting of polyether-based electrolyte materials such as polyethylene oxide, polypropylene oxide, ethylene oxide-propylene copolymer, and dimethylsiloxane-ethylene oxide copolymer; gel polymer electrolyte materials such as polyacrylonitrile, polyvinylidene fluoride, and vinylidene fluoride-hexafluoropropylene polymer; and polymer solid electrolyte materials using hyperbranched polymers.

[0038] The content of the solid electrolyte in the positive electrode active material layer of this embodiment, when the entire positive electrode active material layer is taken as 100 parts by mass, is preferably 5.0 parts by mass or more and 40.0 parts by mass or less, more preferably 8.0 parts by mass or more and 35.0 parts by mass or less, even more preferably 10.0 parts by mass or more and 33.0 parts by mass or less, even more preferably 12.0 parts by mass or more and 30.0 parts by mass or less, and even more preferably 14.0 parts by mass or more and 28.0 parts by mass or less, from the viewpoint of further improving the cycle characteristics of the all-solid-state battery.

[0039] The positive electrode active material layer of this embodiment preferably further contains a conductive additive from the viewpoint of further improving the cycle characteristics of the all-solid-state battery. From the viewpoint of further improving the cycle characteristics of the all-solid-state battery, the conductive additive in the positive electrode active material layer of the present embodiment contains one or more selected from the group consisting of carbon black, activated carbon, graphite, mesoporous carbon, fullerenes, carbon nanotubes, carbon nanofibers, and carbon brushes, and more preferably contains carbon black.

[0040] The content of the conductive additive in the positive electrode active material layer of this embodiment is preferably 0.1 parts by mass or more and 10.0 parts by mass or less, more preferably 0.3 parts by mass or more and 5.0 parts by mass or less, even more preferably 0.5 parts by mass or more and 4.0 parts by mass or less, even more preferably 0.8 parts by mass or more and 3.0 parts by mass or less, and even more preferably 1.0 parts by mass or more and 2.0 parts by mass or less, when the entire positive electrode active material layer is taken as 100 parts by mass, from the viewpoint of further improving the cycle characteristics of the all-solid-state battery.

[0041] The density of the positive electrode active material layer of this embodiment is preferably 1.0 g / cm 3 More than 5.0g / cm 3 or less, more preferably 2.0 g / cm 3 More than 4.0g / cm 3 The following is the result.

[0042] The thickness of the positive electrode active material layer is not particularly limited, but is, for example, preferably from 1 μm to 150 μm, more preferably from 5 μm to 100 μm, and even more preferably from 10 μm to 80 μm.

[0043] The positive electrode of this embodiment may further include a positive electrode current collector 3 . The positive electrode current collector includes, for example, one or more selected from the group consisting of aluminum, stainless steel, nickel, titanium, and alloys thereof. The positive electrode current collector may be in the form of, for example, a foil, a flat plate, or a mesh. The thickness of the positive electrode current collector is, for example, 1 μm or more and 50 μm or less.

[0044] (Negative electrode) The negative electrode of this embodiment includes a negative electrode active material layer. The negative electrode active material layer of this embodiment contains, for example, a negative electrode active material, and may further contain one or more materials selected from the group consisting of a negative electrode binder resin, a solid electrolyte, and a conductive additive.

[0045] From the perspective of further improving the cycle characteristics of the all-solid-state battery, the negative electrode active material of the present embodiment preferably contains one or more negative electrode active materials selected from the group consisting of a carbon material, a lithium-based metal material, a Si-based material, and a conductive polymer material.

[0046] Examples of the carbon material include graphite, amorphous carbon, diamond-like carbon, fullerene, carbon nanotube, carbon nanohorn, and the like. Examples of the lithium-based metal material include metallic lithium, lithium alloy, and the like. Examples of the Si-based material include Si, SiO2, SiO x (0 < x ≤ 2), Si-containing composite materials, and the like. Examples of the conductive polymer material include polyacene, polyacetylene, polypyrrole, and the like.

[0047] When the total amount of the negative electrode active material layer is 100 parts by mass, the content of the negative electrode active material in the negative electrode active material layer of the present embodiment is preferably 70 parts by mass or more and 100 parts by mass or less, more preferably 80 parts by mass or more and 100 parts by mass or less, and still more preferably 90 parts by mass or more and 100 parts by mass or less.

[0048] The negative electrode active material layer of the present embodiment may contain one or more binder resins selected from the group consisting of a fluorine-based binder resin, a rubber-based binder resin, and an acrylic-based binder resin. Such a binder resin may be in an emulsion form. When water is used as the solvent, it is preferable to use a water-based binder resin and a thickener such as CMC (carboxymethyl cellulose) in combination.

[0049] When the total amount of the negative electrode active material layer is 100 parts by mass, the content of the binder resin in the negative electrode active material layer of the present embodiment may be, for example, 1 part by mass or more and 10 parts by mass or less, or may be 3 parts by mass or more and 6 parts by mass or less.

[0050] The solid electrolyte in the negative electrode active material layer of the present embodiment preferably includes one or more selected from the group consisting of a sulfide-based solid electrolyte, an oxide-based solid electrolyte, and a polymer electrolyte, and more preferably includes a sulfide-based solid electrolyte.

[0051] Examples of oxide-based solid electrolytes include NASICON-type solid electrolyte materials such as LiTi2(PO4)3, LiZr2(PO4)3, and LiGe2(PO4)3; 0.5+x Li 0.5-3x ) Perovskite-type solid electrolyte materials such as TiO3; one or more selected from the group consisting of Li2O-P2O5 materials, Li2O-P2O5-Li3N materials, etc.

[0052] Examples of sulfide-based solid electrolytes include Li2S-P2S5 materials, Li2S-SiS2 materials, Li2S-GeS2 materials, Li2S-Al2S3 materials, Li2S-SiS2-Li3PO4 materials, Li2S-P2S5-GeS2 materials, Li2S-Li2O-P2S5-SiS2 materials, Li2S-GeS2-P2S5-SiS2 materials, Li2S-SnS2-P2S5-SiS2 materials, Li2S-P2S5-Li3N materials, and Li2S 2+X -P4S3 material, Li2S-P2S5-P4S3 material, LiPO4-Li2S-SiS material, Li3PS4, Li3PO4-Li2S-Si2S material, Li3PO4-Li2S-SiS2 material, LiI-L i2S-B2S3 material, LiI-Li2S-SiS2 material, LiI-Li2S-P2S5 material, LiI-Li2S-P2O5 material, LiI-Li3PO4-P2S5Li2S-P2S5-LiCl material, Li 7-x PS 6-x Cl x (where 0≦x≦2), Li 7-x PS 6-x Br x (where 0≦x≦2), Li 7-x PS 6-x I x (where 0≦x≦2), Li 10 GeP2S 12 , and Li 3.25 Ge 0.25 P 0.75S4, more preferably Li 7-x PS 6-x Cl x (where 0≦x≦2), Li 7-x PS 6-x Br x (where 0≦x≦2) and Li 7-x PS 6-x I x (where 0≦x≦2), more preferably contains one or more selected from the group consisting of Li6PS5Cl, Li6PS5Br and Li6PS5I, and even more preferably contains Li6PS5Cl.

[0053] The polymer-based solid electrolyte material includes one or more selected from the group consisting of polyether-based electrolyte materials such as polyethylene oxide, polypropylene oxide, ethylene oxide-propylene copolymer, and dimethylsiloxane-ethylene oxide copolymer; gel polymer electrolyte materials such as polyacrylonitrile, polyvinylidene fluoride, and vinylidene fluoride-hexafluoropropylene polymer; and polymer solid electrolyte materials using hyperbranched polymers.

[0054] From the viewpoint of further improving the cycle characteristics of the all-solid-state battery, the conductive additive in the negative electrode active material layer of the present embodiment includes one or more selected from the group consisting of carbon black, activated carbon, graphite, mesoporous carbon, fullerenes, carbon nanotubes, carbon nanofibers, and carbon brushes, and more preferably includes carbon black.

[0055] The content of the conductive additive in the negative electrode active material layer of this embodiment is 0.05 parts by mass or more and 10 parts by mass or less, preferably 0.5 parts by mass or more and 5.0 parts by mass or less, when the entire negative electrode active material layer is taken as 100 parts by mass, from the viewpoint of further improving the cycle characteristics of the all-solid-state battery.

[0056] In the negative electrode active material layer, electrode additives generally used for forming electrodes, such as thickeners, dispersants, and stabilizers, can be used as appropriate.

[0057] The density of the negative electrode active material layer of this embodiment is preferably 0.5 g / cm 3 More than 3.0g / cm 3 or less, more preferably 1.2 g / cm 3 More than 2.0g / cm 3 The following is the result.

[0058] The thickness of the negative electrode active material layer of this embodiment is preferably 1 μm or more and 150 μm or less, more preferably 5 μm or more and 100 μm or less, and even more preferably 10 μm or more and 80 μm or less.

[0059] The negative electrode of this embodiment may further include a negative electrode current collector 4. The negative electrode current collector includes, for example, one or more materials selected from the group consisting of copper, stainless steel, nickel, titanium, and alloys thereof. The negative electrode current collector may be in the form of, for example, a foil, a flat plate, or a mesh. The thickness of the negative electrode current collector is, for example, 1 μm or more and 50 μm or less.

[0060] (Any configuration of all-solid-state battery) The all-solid-state battery of this embodiment can further include exterior bodies 6 and 7. Examples of the exterior body include an aluminum laminate film, a strong aluminum can case, and a cylindrical aluminum exterior body.

[0061] The all-solid-state battery of this embodiment may further include a positive electrode terminal 9 and a negative electrode terminal 8. The positive electrode terminal may be made of, for example, aluminum or an aluminum alloy, and the negative electrode terminal may be made of, for example, copper or a copper alloy, or a nickel-plated copper or copper alloy.

[0062] <Manufacturing method for all-solid-state batteries> The method for producing the all-solid-state battery is not particularly limited, and known methods can be applied. First, the preparation of the negative electrode will be described. The negative electrode can be prepared by a known method. Regardless of the method used to prepare the negative electrode, it is preferable to prepare it in a low-moisture environment under dew point control in order to suppress adsorption of moisture into the solid electrolyte.

[0063] When using a negative electrode in which a negative electrode active material layer is formed on a negative electrode current collector, a slurry in which a negative electrode active material, a solid electrolyte, and a binder resin are dispersed in a dehydrated organic solvent is applied to part or all of the surface of a negative electrode current collector such as copper foil and dried to obtain a negative electrode precursor sheet. The obtained negative electrode precursor sheet can be compressed using a press molding method such as a roll press, a uniaxial press, a rubber press, or an isostatic press (CIP method, WIP method), to obtain a negative electrode sheet. The organic solvent preferably includes one or more solvents selected from the group consisting of tertiary amine solvents such as acetonitrile, xylene, dimethoxyethane, dimethyl carbonate, and triethylamine, as well as heptane, hexane, tetrahydrofuran, toluene, and N-methylpyrrolidone, as well as ether solvents, thiol solvents, and butyl butyrate, and all of these solvents are preferably dehydrated.

[0064] The negative electrode can be obtained by placing a metallic lithium layer (negative electrode active material layer) such as lithium foil on part or all of a negative electrode current collector such as stainless steel foil, and then adhering them together by rolling or other processing.

[0065] Next, a solid electrolyte layer is formed on the surface of the negative electrode. When a sulfide-based solid electrolyte is used, it is preferably formed in a low-moisture environment under dew point control to prevent moisture adsorption.

[0066] The solid electrolyte layer can be formed on the surface of the negative electrode by, for example, applying a slurry of a solid electrolyte dispersed in an organic solvent to the surface of a negative electrode active material layer formed on a negative electrode current collector and drying the slurry. The organic solvent may include, for example, one or more selected from the group consisting of acetonitrile, xylene, dimethoxyethane, dimethyl carbonate, triethylamine, and other tertiary amine solvents, heptane, hexane, tetrahydrofuran, toluene, N-methylpyrrolidone, as well as ether solvents, thiol solvents, and butyl butyrate, and it is preferable that all of the organic solvents have been dehydrated.

[0067] Next, the stacked negative electrode and solid electrolyte layer are compressed using a press molding method such as a vacuum laminator, roll press, uniaxial press, rubber press, or isostatic pressing (CIP method, WIP method), to obtain a negative electrode-solid electrolyte layer laminate. When the solid electrolyte layer is stacked together with a substrate layer such as a polyester sheet and pressurized, the substrate layer is peeled off from the solid electrolyte layer. In this case, it is also preferable to use a substrate layer whose surface is coated with a release agent such as silicone, so that the substrate layer can be easily peeled off from the solid electrolyte layer.

[0068] Next, the fabrication of the positive electrode will be described. Regardless of the method used to fabricate the positive electrode, it is preferable to fabricate the positive electrode in a low moisture environment under dew point control in order to suppress moisture adsorption.

[0069] The positive electrode of this embodiment can be produced, for example, by a method (hereinafter sometimes referred to as Method A) in which the components constituting the positive electrode active material layer are dissolved or dispersed in a solvent to produce a positive electrode slurry, and the positive electrode slurry is applied to at least one surface of a positive electrode current collector, followed by drying and rolling. A roll press is preferably used for rolling, and the pressure during rolling is preferably 500 kg / cm or more and 10,000 kg / cm or less, more preferably 1,000 kg / cm or more and 8,000 kg / cm or less, and even more preferably 3,000 kg / cm or more and 6,000 kg / cm or less. Furthermore, the temperature during rolling is preferably 40°C or more and 100°C or less, more preferably 60°C or more and 95°C or less, and even more preferably 70°C or more and 90°C or less. The positive electrode of this embodiment can also be produced by, for example, applying the positive electrode slurry onto a support, drying it, and then peeling it off from the support to obtain a film, which is then laminated onto a positive electrode current collector (hereinafter, this may be referred to as Method B). The solvent preferably includes one or more solvents selected from the group consisting of acetonitrile, xylene, dimethoxyethane, dimethyl carbonate, tertiary amine solvents such as triethylamine, heptane, hexane, tetrahydrofuran, toluene, N-methylpyrrolidone, ether solvents, thiol solvents, and butyl butyrate, and all of these solvents are preferably dehydrated.

[0070] A positive electrode is laminated on the negative electrode-solid electrolyte layer laminate to obtain an electrode laminate precursor. When a sulfide-based solid electrolyte is used as the solid electrolyte, the ionic conductivity of the solid electrolyte may decrease due to exposure to moisture. Therefore, it is preferable to obtain the electrode laminate precursor and then compress the electrode laminate precursor to obtain the electrode laminate. The electrode laminate precursor is preferably compressed using one or more methods selected from the group consisting of a vacuum laminator, a roll press, a uniaxial press, a rubber press, and an isostatic press (CIP method, WIP method), and more preferably compressed using a combination of a vacuum laminator and an isostatic press (CIP method). The temperature conditions for compressing the electrode laminate precursor are preferably 10°C to 40°C, more preferably 15°C to 30°C, and even more preferably 20°C to 30°C. The compression time for the electrode laminate precursor is preferably 0.5 minutes to 20 minutes, more preferably 0.5 minutes to 15 minutes, even more preferably 0.5 minutes to 10 minutes, and even more preferably 0.5 minutes to 5 minutes. The pressure conditions for compressing the electrode laminate precursor are preferably more than 300 MPa to 1500 MPa, more preferably 350 MPa to 1400 MPa, even more preferably 375 MPa to 1200 MPa, and even more preferably 400 MPa to 1000 MPa. Furthermore, in the case of a manufacturing method that does not include a rolling step when preparing the positive electrode, such as method B, the pressure conditions for compressing the electrode laminate precursor are preferably 500 MPa or more and 1500 MPa or less, more preferably 550 MPa or more and 1300 MPa or less, even more preferably 600 MPa or more and 1200 MPa or less, and even more preferably 650 MPa or more and 1100 MPa or less.

[0071] The resulting electrode laminate is preferably quickly sealed in an exterior housing. One end of a rectangular metal plate serving as a negative electrode terminal is attached to the negative electrode current collector, and one end of a rectangular metal terminal serving as a positive electrode terminal is attached to the positive electrode current collector, and then the electrode laminate is housed in an aluminum exterior housing. A resin layer such as polyolefin is preferably formed on at least the surface of the inner surface of the exterior housing facing the electrode laminate. The resin layer is heated to melt the resin and then solidify it again, and the electrode laminate is sealed in the aluminum exterior housing. At this time, the other end of the positive electrode terminal and the other end of the negative electrode terminal are positioned so as to extend outside the exterior housing. A layer of resin of the same type or a different type from the resin used in the resin layer on the interior surface of the exterior housing can be provided in the areas where the positive electrode terminal and the negative electrode terminal contact the resin layer on the interior surface of the exterior housing.

[0072] <Battery module> The battery module of this embodiment includes the all-solid-state battery of this embodiment. The all-solid-state battery of this embodiment can improve the cycle characteristics, and therefore the battery module of this embodiment can improve the cycle characteristics.

[0073] The battery module of this embodiment preferably includes two or more all-solid-state batteries of this embodiment connected in series or in parallel. The battery module of this embodiment more preferably includes a housing capable of accommodating two or more all-solid-state batteries of this embodiment connected in series or in parallel. The battery module of this embodiment further preferably includes one or more components selected from the group consisting of a protection circuit that protects the all-solid-state battery from overcurrent, a balancing circuit that equalizes the voltage between the electrodes of the all-solid-state battery, a controller that controls the all-solid-state battery, a cooler that can cool the all-solid-state battery, and a heater that can heat the all-solid-state battery.

[0074] The battery module of this embodiment can be used in a battery system including a plurality of electrically connected battery modules and a battery control system. Examples of battery systems include battery packs, stationary storage battery systems, automotive power storage battery systems, automotive auxiliary storage battery systems, and emergency power storage battery systems.

[0075] The present invention is not limited to the above-described embodiment, and the present invention includes modifications and improvements within the scope of achieving the object of the present invention. [Example]

[0076] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

[0077] Example 1 An all-solid-state battery was fabricated by the following method.

[0078] [I] Preparation of anode-solid electrolyte layer stack (1) A foil (manufactured by Honjo Metals Co., Ltd.) was prepared as a negative electrode, in which a 20 μm thick metallic lithium layer was formed on the surface of a 10 μm thick stainless steel negative electrode current collector. (2) A slurry prepared by dispersing a solid electrolyte and a binder resin in xylene was applied to the surface of a polyester film mainly composed of polyester, followed by drying to form a solid electrolyte layer on the polyester film. The solid electrolyte layer was then laminated on the negative electrode together with the polyester film so that the solid electrolyte layer was in contact with the surface of the metallic lithium layer of the negative electrode, thereby obtaining a negative electrode-solid electrolyte layer laminate. (3) The anode-solid electrolyte layer laminate obtained in (2) above was vacuum-sealed using a vacuum laminator and held at room temperature (25°C) under a pressure of 300 MPa for 1 minute. The anode-solid electrolyte layer laminate was then removed from the vacuum laminator and compressed by isostatic pressing (CIP) at room temperature (25°C) under a pressure of 300 MPa for 1 minute to obtain an anode-solid electrolyte layer laminate. The size of the anode-solid electrolyte layer laminate was 26 mm × 26 mm. (4) The polyester film was peeled off from the solid electrolyte layer to obtain a negative electrode-solid electrolyte layer laminate.

[0079] [II] Lamination of positive electrode and negative electrode-solid electrolyte layer laminate (1) A positive electrode active material, a solid electrolyte, a conductive additive, and a binder resin were dispersed in butyl butyrate to obtain a slurry. The slurry was then applied to a 10 μm-thick aluminum foil and dried to form a positive electrode active material layer. The resulting layer was then heated and roll-pressed at 80°C and 5000 kg / cm to obtain a positive electrode. (2) The cathode obtained in (1) above was cut into a 20 mm × 20 mm piece, and the cathode and the anode-solid electrolyte layer laminate prepared in [I] above were laminated together so that the cathode active material layer was in contact with the solid electrolyte layer of the anode-solid electrolyte layer laminate, thereby obtaining an electrode laminate precursor. The number of layers of the cathode and anode-solid electrolyte layer laminate was one each.

[0080] [III] Preparation of electrode stack The electrode laminate precursor obtained in [II] above was vacuum sealed using a vacuum laminator and held at room temperature (25°C) under a pressure of 400 MPa for 1 minute. The electrode laminate precursor was then removed from the vacuum laminator and compressed by a CIP method at room temperature (25°C) under a pressure of 400 MPa for 1 minute to obtain an electrode laminate.

[0081] [IV] Encapsulation in an outer packaging The electrode laminate obtained in [III] above was enclosed in an aluminum exterior body (manufactured by Dai Nippon Printing Co., Ltd.) by the method described in the embodiment, and an all-solid-state battery in which the positive electrode terminal and the negative electrode terminal were extended to the outside of the exterior body was obtained.

[0082] Example 2 An all-solid-state battery was produced in the same manner as in Example 1, except that the hot roll press was not performed when producing the positive electrode, and the pressure conditions for the electrode laminate precursor by the CIP method were changed to the conditions shown in Table 1.

[0083] (Comparative Example 1) An all-solid-state battery was produced in the same manner as in Example 1, except that the conditions for pressing the electrode laminate precursor by the CIP method were changed to the conditions shown in Table 1.

[0084] <Average particle diameter d of the solid electrolyte and the positive electrode active material 50 Measurement method> The average particle diameter d of the solid electrolyte and the positive electrode active material at 50% cumulative volume in the volume-based particle size distribution measured by the laser diffraction scattering particle size distribution measurement method 50 were measured using a laser diffraction / scattering particle size distribution analyzer (Microtrac, MT3000).

[0085] <Evaluation of the interface between the positive electrode active material layer and the solid electrolyte layer> The all-solid-state battery obtained by the above method was subjected to evaluation of the interface between the positive electrode active material layer and the solid electrolyte layer. The evaluation method is as follows. With the direction in which the positive electrode active material layer and the solid electrolyte layer were stacked vertically, a cross section of the positive electrode active material layer and the solid electrolyte layer was photographed at a magnification of 2000 times using a scanning electron microscope (SEM) so that the interface between the positive electrode active material layer and the solid electrolyte layer included 60 μm or more in the horizontal direction. The obtained cross-sectional SEM images were used to measure the linear length and contact length of the interface between the positive electrode active material layer and the solid electrolyte layer using Image J (National Institutes of Health, USA). The contact length refers to the length of the contact surface obtained by sampling the contact points between the positive electrode active material and the solid electrolyte in a 60 μm horizontal section in the cross-sectional SEM image and connecting each contact point with a straight line. The linear length refers to the length of the line obtained by connecting the two ends of the contact points sampled when measuring the contact length with a straight line and projecting the line onto a horizontal plane. The value obtained by dividing the contact length by the linear length is the ratio of contact length to linear length, and the calculation results are shown in Table 1. The ratio of contact length to linear length was measured at a total of nine locations shown in Figure 2, including the center in the planar direction of the interface between the positive electrode active material layer and the solid electrolyte layer, and the average value was used.

[0086] <Cycle test> The cycle characteristics of the all-solid-state battery were evaluated by repeatedly charging and discharging the all-solid-state battery obtained by the above method under the following charging and discharging conditions. Charging: Constant current-constant voltage, rate = 1C Discharge: Constant current, rate = 1C Note that "C" is the symbol for the current rate (time rate). A rate of 1C will fully discharge the rated capacity of the battery in 1 hour. In the above cycle test, the ratio of the discharge capacity after the second charge / discharge to the initial discharge capacity is called the capacity retention rate. The battery was repeatedly charged and discharged under the above charge and discharge conditions, and the capacity retention rate after 100 charge and discharge tests, i.e., the 100th cycle, was determined and designated as the “capacity retention rate at 1 C.” The results are shown in Table 1. The results obtained are shown in Table 1.

[0087] [Table 1]

[0088] The raw materials of the all-solid-state batteries of Examples 1 and 2 and Comparative Example 1 are as follows. <Positive electrode> ·Cathode active material: LiNi 0.8 Co 0.1 Mn 0.1 O2(average particle diameter d 50 : 5 μm), content in positive electrode active material layer: 76 mass% ·Solid electrolyte: Li6PS5Cl (average particle size d 50 : 6.5 μm), content in positive electrode active material layer: 19.5 mass% Conductive additive: CB (carbon black), content in positive electrode active material layer: 1.5% by mass Binder resin: SBR (styrene-butadiene rubber), content in positive electrode active material layer: 3% by mass

[0089] <Solid electrolyte layer> ·Solid electrolyte: Li6PS5Cl (average particle size d 50 : 6.5 μm), content in solid electrolyte layer: 95 mass% Binder resin: SBR (styrene-butadiene rubber), content in solid electrolyte layer: 5% by mass [Explanation of symbols]

[0090] 1 Cathode active material layer 2 Negative electrode active material layer 3 Positive electrode current collector 4 Negative electrode current collector 5 Solid electrolyte layer 6. Exterior body 7. Exterior body 8 Negative terminal 9 Positive terminal 10 All-solid-state battery a1~a9 area b1 and b4 centerlines Straight lines b2-b3 and b5-b6 The vertical distance between each line d1~d6 O center α Interface between the positive electrode active material layer and the solid electrolyte layer

Claims

1. a positive electrode including a positive electrode active material layer; a solid electrolyte layer containing a solid electrolyte (A); a negative electrode including a negative electrode active material layer; in this order, the positive electrode active material layer and the solid electrolyte layer are in contact with each other, The contact length of the interface between the positive electrode active material layer and the solid electrolyte layer, measured by the following method, is defined as L １ The straight line length is L ２ When this is done, L １ and L ２ The ratio (L １ / L ２ ) is 1.1 or more and 1.4 or less. (method) A cross section of the cathode active material layer and the solid electrolyte layer is photographed at a magnification of 2000x using a scanning electron microscope (SEM), with the stacking direction of the cathode active material layer and the solid electrolyte layer being the vertical direction, so that the interface between the cathode active material layer and the solid electrolyte layer includes at least 60 μm in the horizontal direction. From the obtained cross-sectional SEM image, the linear length and contact length of the interface between the cathode active material layer and the solid electrolyte layer are measured using image analysis software. The contact length is the length of the contact surface obtained by sampling contact points between the cathode active material and the solid electrolyte in a 60 μm section in the horizontal direction in the cross-sectional SEM image and connecting each contact point with a straight line. The linear length is the length of the line obtained by connecting the two ends of the contact points sampled when measuring the contact length with a straight line and projecting the line onto a horizontal plane.

2. 2. The all-solid-state battery according to claim 1, wherein the solid electrolyte (A) comprises one or more selected from the group consisting of sulfide-based solid electrolytes, oxide-based solid electrolytes, and polymer electrolytes.

3. 3. The all-solid-state battery according to claim 1, wherein a content of the solid electrolyte (A) in the solid electrolyte layer is 50.0 parts by mass or more and 100.0 parts by mass or less, when the total amount of the solid electrolyte layer is 100.0 parts by mass.

4. 4. The all-solid-state battery according to claim 1, wherein the positive electrode active material layer contains, as a positive electrode active material, a lithium composite oxide having a layered rock salt crystal structure.

5. 5. The all-solid-state battery according to claim 4, wherein the lithium composite oxide comprises one or more selected from the group consisting of lithium-nickel composite oxide, lithium-cobalt composite oxide, lithium-nickel-aluminum composite oxide, and lithium-nickel-cobalt-manganese composite oxide.

6. 6. The all-solid-state battery according to claim 5, wherein the lithium composite oxide includes a lithium-nickel-cobalt-manganese composite oxide.

7. 7. The all-solid-state battery according to claim 1, wherein the negative electrode active material layer comprises one or more negative electrode active materials selected from the group consisting of carbon materials, lithium-based metal materials, Si-based materials, and conductive polymer materials.

8. A battery module comprising the all-solid-state battery according to any one of claims 1 to 7.

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