All-solid-state batteries

Abstract

Provided is an all-solid-state battery in which short circuits between the positive electrode layer and the negative electrode layer are suppressed even after repeated charge and discharge, and which has excellent cycle characteristics. 【Solution Means】An all-solid-state battery comprising a laminate in which a positive electrode current collector, a positive electrode active material layer, an insulating layer, a solid electrolyte layer, a negative electrode active material layer, and a negative electrode current collector are laminated, wherein the overhang length (a) of the negative electrode active material layer from the end of the positive electrode active material layer to the end of the negative electrode active material layer, the overhang length (b) of the solid electrolyte layer from the end of the positive electrode active material layer to the end of the solid electrolyte layer, the overhang length (c) of the insulating layer from the end of the positive electrode active material layer to the outer end of the insulating layer, the thickness of the solid electrolyte layer (t s ), the thickness of the insulating layer (t p ), and the voltage during discharge (d) satisfy the relationships a<b<c, and c-b+t s +t p >0.2 / 12×d.

Description

[Technical Field]

[0001] This invention relates to an all-solid-state battery. [Background technology]

[0002] In recent years, research and development has been conducted on rechargeable batteries that contribute to energy efficiency, in order to ensure that more people have access to affordable, reliable, sustainable, and advanced energy. Among rechargeable batteries, all-solid-state batteries, which have superior characteristics in terms of safety, lifespan, and output, are attracting attention.

[0003] In all-solid-state batteries, metallic lithium dendrites (tree-like crystals) may precipitate in the negative electrode layer during charging. Furthermore, repeated charging and discharging can reduce the adhesion at the interface between the negative electrode layer and the solid electrolyte layer, which may promote the deposition of lithium metal dendrites. If lithium ions precipitate at the edges of the solid electrolyte layer, the accumulation of the precipitated lithium may cause a short circuit between the positive and negative electrode layers, or localized side reactions may occur, increasing the resistance within the battery and potentially degrading the cycle characteristics.

[0004] In an all-solid-state battery including a laminated structure composed of a positive electrode layer, a solid electrolyte layer, and a negative electrode layer, a method is known to reduce lithium metal deposition during charging by arranging a highly ion-conductive solid electrolyte layer on the inside and a low-ion-conductive solid electrolyte layer on the outside in a direction perpendicular to the lamination direction, and controlling the position of the outer peripheral edge of the positive electrode layer and the arrangement of the highly ion-conductive and low-ion-conductive solid electrolyte layers (see, for example, Patent Document 1). That is, according to the all-solid-state battery disclosed in Patent Document 1, by designing the position of the outer peripheral edge of the positive electrode layer, the position of the inner peripheral edge of the insulating layer, and the overlap of the low-ion-conductive solid electrolyte layer to be appropriately arranged in a plan view, concentrated stress is generated at the outer peripheral edge of the positive electrode layer and the inner peripheral edge of the insulating layer due to the pressure in the thickness direction of each layer, and since low-ion-conductive parts are arranged at these concentrated stress locations, lithium metal deposition during charging can be reduced. However, even if the precipitation of lithium metal during charging can be reduced within a certain range by controlling the arrangement of the end portion of the laminate to have a specific configuration as in the all-solid-state battery disclosed in Patent Document 1, there is still room for improvement in order to prevent a short circuit between the positive electrode layer and the negative electrode layer upon repeated charge and discharge and provide an all-solid-state battery with excellent cycle characteristics. [Prior Art Documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Unexamined Patent Publication No. 2023-47083 [Summary of Invention] [Problem to be Solved by the Invention]

[0006] The present invention has been made in view of the above circumstances, and an object thereof is to provide an all-solid-state battery that prevents a short circuit between a positive electrode layer and a negative electrode layer even after repeated charge and discharge and has excellent cycle characteristics. Furthermore, it contributes to the improvement of energy efficiency. [Means for Solving the Problem]

[0007] As a result of studying the relationship between the voltage of an all-solid-state battery, the thickness of each layer of the laminate included in the battery, and the arrangement of the outer peripheral end of each layer, the present inventors have found that when these satisfy a specific relationship, a short circuit between the positive electrode layer and the negative electrode layer can be further prevented even after repeated charge and discharge. The inventors have also found that by controlling the size of the solid electrolyte layer within a specific range, the occurrence of burrs during production can be efficiently suppressed, whereby precipitation of lithium ions at the end portion of the solid electrolyte layer or the like, particularly dendrite growth, can be suppressed, and a short circuit between the positive electrode layer and the negative electrode layer and local side reactions can be suppressed, even after repeated charge and discharge, and the present invention has been completed. That is, the present invention includes the following aspects.

[0008] [1]Comprising a positive electrode current collector, a positive electrode active material layer, an insulating layer, a solid electrolyte layer, a negative electrode active material layer, and a negative electrode current collector, The positive electrode current collector, the positive electrode active material layer, the solid electrolyte layer, the negative electrode active material layer, and the negative electrode current collector are laminated in this order, and the insulating layer is an all-solid-state battery including a laminate arranged to surround the outer periphery of the positive electrode active material layer, wherein Each layer of the laminate is configured such that, in a plan view, the outer peripheral end of the positive electrode active material layer, the outer peripheral end of the negative electrode active material layer, the outer peripheral end of the solid electrolyte layer, and the outer peripheral end of the insulating layer are positioned outward in this order, In a cross section parallel to the lamination direction passing through a straight line parallel to the longitudinal direction of the laminate, Let a be the difference between the shortest distance from the center in the longitudinal direction of the negative electrode active material layer to one end, and the shortest distance from the center in the longitudinal direction of the positive electrode active material layer to the end in the same direction as the end of the negative electrode active material layer, Let b be the difference between the shortest distance from the center in the longitudinal direction of the solid electrolyte layer to the end in the same direction as the end of the negative electrode active material layer, and the shortest distance from the center in the longitudinal direction of the positive electrode active material layer to the end in the same direction as the end of the negative electrode active material layer, Let c be the difference between the shortest distance from the center in the longitudinal direction of the positive electrode active material layer to the outer end of the insulating layer in the same direction as the end of the negative electrode active material layer, and the shortest distance from the center in the longitudinal direction of the positive electrode active material layer to the end in the same direction as the end of the negative electrode active material layer, Let t be the thickness of the solid electrolyte layer at the end of the solid electrolyte layer s , Let t be the thickness of the insulating layer at the outer end of the insulating layer p , and let d(V) be the voltage during discharge, The all-solid-state battery is configured to satisfy the relationship a<b<c, and satisfy the relationship c-b+t s +t p >0.2 / 12×d.

[0009] [1] According to the all-solid-state battery, the length of the negative electrode active material layer from the edge of the positive electrode active material layer to the edge of the negative electrode active material layer is (a), the length of the solid electrolyte layer from the edge of the positive electrode active material layer to the edge of the solid electrolyte layer is (b), the length of the insulating layer from the edge of the positive electrode active material layer to the outer edge of the insulating layer is (c), and the thickness of the solid electrolyte layer is (t s ), and the thickness of the insulating layer (t p Since the above relationship is satisfied, even after repeated charging and discharging, metal is less likely to accumulate at the edges of the solid electrolyte. Furthermore, even if metal is deposited at the edges of the solid electrolyte, the large creepage distance from the negative electrode active material layer to the positive electrode current collector suppresses short circuits between the positive and negative electrode layers, improving the cycle characteristics.

[0010] [2] The all-solid-state battery according to [1], comprising a laminate further comprising an intermediate layer between the negative electrode active material layer and the solid electrolyte layer, wherein in a plan view of the laminate, the outer peripheral edge of the intermediate layer is located outside the outer peripheral edge of the negative electrode active material layer and at the same position as or inside the outer peripheral edge of the solid electrolyte layer.

[0011] [2] According to the all-solid-state battery, metal deposition, especially dendrite growth, can be suppressed, and even after repeated charging and discharging, metal is less likely to accumulate at the edges of the solid electrolyte, thus further suppressing short circuits between the positive and negative electrode layers and improving cycle characteristics.

[0012] [3] b, c and t s However, cb>t s A solid-state battery as described in [1] or [2], configured to satisfy the following relationship.

[0013] [3] According to the all-solid-state battery, the generation of burrs in the solid electrolyte layer can be efficiently suppressed during the manufacturing of the all-solid-state battery. Therefore, even after repeated charging and discharging, the deposition of metal at the edges of the solid electrolyte layer, particularly the growth of dendrites, can be suppressed, and short circuits between the positive and negative electrode layers and localized side reactions can be further suppressed.

[0014] [4] The all-solid-state battery according to any one of [1] to [3], wherein when a distance from one end to the other end in the longitudinal direction of the negative electrode active material layer is defined as e, the a, b and e are configured to satisfy a relationship of b>a+(e×0.01).

[0015] According to the all-solid-state battery of [4], even when pressing at high pressure in the stacking direction of the all-solid-state battery, the elongation rate of the negative electrode active material layer in the direction orthogonal to the stacking direction is taken into consideration, so the configurations of the above [1] to [3] can be provided more accurately and / or stably.

[0016] [5] In a cross section parallel to the stacking direction passing through a straight line parallel to the lateral direction of the laminate, A difference between the shortest distance from the center in the lateral direction of the negative electrode active material layer to one end, and the shortest distance from the center in the lateral direction of the positive electrode active material layer to the end in the same direction as the end of the negative electrode active material layer is defined as a', A difference between the shortest distance from the center in the lateral direction of the solid electrolyte layer to the end in the same direction as the end of the negative electrode active material layer, and the shortest distance from the center in the lateral direction of the positive electrode active material layer to the end in the same direction as the end of the negative electrode active material layer is defined as b', A difference between the shortest distance from the center in the lateral direction of the positive electrode active material layer to the outer end of the insulating layer in the same direction as the end of the negative electrode active material layer, and the shortest distance from the center in the lateral direction of the positive electrode active material layer to the end in the same direction as the end of the negative electrode active material layer is defined as c', The thickness of the solid electrolyte layer at the end of the solid electrolyte layer is defined as t s ', The thickness of the insulating layer at the outer end of the insulating layer is defined as t p ', When the voltage during discharge is defined as d(V), The all-solid-state battery according to any one of [1] to [4], which is configured to satisfy the relationship of a'<b'<c' and satisfy the relationship of c'-b'+t s '+t p '>0.2 / 12×d.

[0017] According to the all-solid-state battery of [5], the length of the negative electrode active material layer from the end of the positive electrode active material layer to the end of the negative electrode active material layer in a direction different from that of [1] to [4] above (a'), the length of the solid electrolyte layer from the end of the positive electrode active material layer to the end of the solid electrolyte layer (b'), the length of the insulating layer from the end of the positive electrode active material layer to the outer end of the insulating layer (c'), and the thickness of the solid electrolyte layer (t s '), and the thickness of the insulating layer (t p The above relationship is satisfied. As a result, even after repeated charging and discharging, metal is less likely to accumulate at the edges of the solid electrolyte. Furthermore, even if metal is deposited at the edges of the solid electrolyte, the creepage distance from the negative electrode active material layer to the positive electrode current collector is large, which further suppresses short circuits between the positive and negative electrode layers, improving the cycle characteristics.

[0018] [6] The above b' and c' and t s 'but, c'-b'>t s A solid-state battery as described in [5], configured to satisfy the relationship '.

[0019] According to the all-solid-state battery of [6], the overhang length of the solid electrolyte layer from the end of the positive electrode active material layer to the end of the solid electrolyte layer in a direction different from that of [1] to [4] above (b'), the overhang length of the insulating layer from the end of the positive electrode active material layer to the outer end of the insulating layer (c'), and the thickness of the solid electrolyte layer (t s The above relationship is satisfied. As a result, the generation of burrs in the solid electrolyte layer can be suppressed more efficiently during the manufacturing of all-solid-state batteries, so that even after repeated charging and discharging, the deposition of metal at the edges of the solid electrolyte layer, especially the growth of dendrites, can be suppressed more effectively, and short circuits between the positive electrode layer and the negative electrode layer, as well as localized side reactions, can be suppressed more effectively.

[0020] [7] The all-solid-state battery according to [5] or [6], wherein when e' is the distance from one end to the other end in the short direction of the negative electrode active material layer, a', b' and e' are configured to satisfy the relationship b'>a'+(e'×0.01).

[0021] In the all-solid-state battery of [7], the overhang length of the negative electrode active material layer from the end of the positive electrode active material layer to the end of the negative electrode active material layer in a direction different from that of [1] to [4] above (a'), the overhang length of the solid electrolyte layer from the end of the positive electrode active material layer to the end of the solid electrolyte layer (b'), and the distance from one end of the negative electrode active material layer to the other end (e') satisfy the above relationship. As a result, even when the all-solid-state battery is pressed under high pressure in the stacking direction, the elongation rate of the negative electrode active material layer in a direction perpendicular to the stacking direction is taken into consideration in a direction different from that of [1] to [4] above, so that the configuration of [5] or [6] above can be easily and / or stably provided.

[0022] [8] Said a, b, c, t s and t p However, the above a', b', c', t s 'and t p A solid-state battery as described in one of [5] to [7], which is the same size as the above.

[0023] [8] According to the all-solid-state battery, it is possible to suppress differences in the characteristics of the all-solid-state battery in different directions in a plan view. [Effects of the Invention]

[0024] According to the present invention, even after repeated charging and discharging, short circuits between the positive electrode layer and the negative electrode layer are suppressed, and an all-solid-state battery with excellent cycle characteristics can be efficiently and / or stably provided. [Brief explanation of the drawing]

[0025] [Figure 1] This is a plan view of a stack of all-solid-state batteries according to one embodiment of the present invention. [Figure 2] This is a cross-sectional view taken along the line A-A' in Figure 1. [Figure 3] This is a cross-sectional view taken along the line B-B' in Figure 1. [Figure 4] This graph shows the relationship between the overhang length (cb) of the insulating layer from the edge of the solid electrolyte layer to the edge of the insulating layer and the height of the burrs of the solid electrolyte layer generated during manufacturing, in an all-solid-state battery according to one embodiment of the present invention. [Modes for carrying out the invention]

[0026] An all-solid-state battery according to an embodiment of the present invention will be described with reference to the drawings. However, the embodiments shown below are illustrative of the present invention and the present invention is not limited to those shown below. In addition, in the drawings used in the following description, the scale of each component may be changed as appropriate in order to make each component recognizable.

[0027] Figure 1 is a plan view of a stack (also called an electrode stack) of an all-solid-state battery according to one embodiment of the present invention. Figure 2 is a cross-sectional view taken along line A-A' in Figure 1, and Figure 3 is a cross-sectional view taken along line B-B' in Figure 1. In Figures 1-3, the longitudinal direction of the laminated structure when viewed from above is shown as the X direction, the transverse direction as the Y direction, and the stacking direction as the Z direction.

[0028] The stack 1 of the all-solid-state battery according to one embodiment of the present invention may be a rectangle in plan view where the length in the X direction is longer than the length in the Y direction, as shown in Figure 1, but is not limited to this. The stack 1 may be a square in plan view where the length in the X direction and the length in the Y direction are the same, or it may be a circle, an ellipse, or an oblong.

[0029] As shown in Figure 2, the laminate 1 includes at least a positive electrode current collector 12, a positive electrode active material layer 11, an insulating layer 15, a solid electrolyte layer 20, a negative electrode active material layer 41, and a negative electrode current collector 42. The positive electrode current collector 12, positive electrode active material layer 11, solid electrolyte layer 20, negative electrode active material layer 41, and negative electrode current collector 42 are stacked in this order, and the insulating layer 15 is arranged to surround the outer circumference of the positive electrode active material layer 11. Preferably, the thickness of the positive electrode active material layer 11 and the thickness of the insulating layer 15 are the same. If the thickness of the positive electrode active material layer 11 and the thickness of the insulating layer 15 are different, unevenness will occur on the surface they form, which can cause distortion and bending of the laminate 1 structure. By having the same thickness for the positive electrode active material layer 11 and the insulating layer 15, a higher quality all-solid-state battery can be manufactured. The positive electrode current collector 12 and the positive electrode active material layer 11 may be collectively referred to as the positive electrode layer 10, and the negative electrode active material layer 41 and the negative electrode current collector 42 may be collectively referred to as the negative electrode layer 40.

[0030] As shown in Figure 2, the laminate 1 may include an intermediate layer 30 between the negative electrode active material layer 41 and the solid electrolyte layer 20. In the laminate 1, as shown in Figure 1, the layers of the positive electrode current collector 12, positive electrode active material layer 11, insulating layer 15, solid electrolyte layer 20, and negative electrode active material layer 41 are configured such that, in a plan view, the outer edges of the positive electrode active material layer 11, the negative electrode active material layer 41, the solid electrolyte layer 20, and the insulating layer 15 are outward in that order. If the laminate 1 includes an intermediate layer 30, the outer edge of the intermediate layer 30 is configured to be at the same position as the outer edge of the solid electrolyte layer 20 in a plan view, as shown in Figure 1, or, although not shown, it may be configured to be inside the outer edge of the solid electrolyte layer 20 and outside the outer edge of the negative electrode active material layer 41.

[0031] In a plan view, the maximum distance from one end to the other in the X direction of the outer edge of the insulating layer 15 may be 450-550 mm, 480-540 mm, or 500-530 mm. In a plan view, the maximum distance from one end to the other in the Y direction of the outer edge of the insulating layer 15 may be 70-120 mm, 80-110 mm, or 85-105 mm.

[0032] The presence of the intermediate layer 30 stabilizes the deposition of metal in the negative electrode active material layer 41 during charging, and in particular reduces the growth of dendrites. Furthermore, by arranging the outer edge of the intermediate layer 30 as described above, the deposition of metal at the edge of the intermediate layer 30, especially the growth of dendrites, can be reduced, and localized side reactions caused by contact between the negative electrode active material layer 41 or the metal deposited on the negative electrode active material layer 41 and the solid electrolyte layer 20 can be suppressed. Moreover, when the negative electrode layer 40 is laminated on the intermediate layer 30 during manufacturing, the generation of burrs on the negative electrode layer 40 near the edge of the intermediate layer 30 can be reduced.

[0033] <Positive electrode current collector> The positive electrode current collector 12, together with the positive electrode active material layer 11, constitutes the positive electrode layer 10. In one embodiment of the present invention, the positive electrode active material layer 11 is laminated on the positive electrode current collector 12, and the insulating layer 15 is arranged on the positive electrode current collector 12 so as to encircle the outer circumference of the positive electrode active material layer 11. Preferably, the area of ​​the positive electrode current collector 12 in plan view is the same as or larger than the area of ​​the positive electrode active material layer 11 in plan view. That is, it is preferable that the positive electrode current collector 12 is sized to cover the side of the positive electrode active material layer 11 facing the positive electrode current collector 12, and may also cover the side of the insulating layer 15 facing the positive electrode current collector 12. The shape of the positive electrode current collector 12 can be a plate or a foil.

[0034] The positive electrode current collector 12 is not particularly limited as long as it functions as a current collector in the positive electrode layer 10, and any positive electrode current collector known for all-solid-state batteries can be used. Examples of materials that make up the positive electrode current collector 12 include aluminum, aluminum alloy, stainless steel, nickel, iron, and titanium, among which aluminum, aluminum alloy, and stainless steel are preferred, and aluminum is particularly preferred.

[0035] <Cathode active material layer> As the material constituting the positive electrode active material layer 11, materials known for constituting the positive electrode active material layer of all-solid-state batteries can be applied. As the positive electrode active material, for example, layered active materials containing lithium, spinel-type active materials, olivine-type active materials, etc., can be applied, and more specifically, LiCoO2, LiNiO2, LiNi p Mn q Co r O2(p+q+r=1), LiNi p Al q Co r O2(p+q+r=1), LiMn2O4, or Li 1+x Mn 2-x-yExamples include compounds represented as MO4 (x+y=2, M=at least one element selected from Al, Mg, Co, Fe, Ni, and Zn), LiMPO4 (M=at least one element selected from Fe, Mn, Co, and Ni), or lithium titanate.

[0036] The positive electrode active material layer 11 may contain a solid electrolyte from the viewpoint of charge transfer medium conductivity, a conductive additive from the viewpoint of conductivity, and a binder from the viewpoint of flexibility. As the solid electrolyte, conductive additive, and binder, those known to be used in the field of positive electrode active material layers for all-solid-state batteries can be applied.

[0037] <Insulating layer> The insulating layer 15 is not particularly limited as long as it electrically insulates the positive electrode current collector 12 and / or the positive electrode active material layer 11 and prevents short circuits between the positive electrode layer and the negative electrode layer. For example, it may have a volume resistivity of 1 × 10⁻⁶ at 20°C. 12 The dielectric strength is Ω·cm or greater, and the dielectric breakdown voltage per unit thickness is preferably 10kV / mm or greater, more preferably 100kV / mm or greater. The insulating layer 15 may be composed of either organic or inorganic materials, and for example, one or more materials selected from rubber, glass, polyimide, polybenzimidazole, polyamideimide, polyetherimide, polyacetal, polyphenylene sulfide, polyetheretherketone, tetrafluoroethylene, polyamide 6 (also called nylon 6), ultra-high molecular weight polyethylene, polyethylene, polypropylene, vinyl chloride resin, polystyrene, polyethylene terephthalate, or ABS resin may be used; or ceramics such as alumina, zirconia, silicon nitride, aluminum nitride, mullite, steatite, magnesia, sialon, or macelite may be used. The insulating layer 15 may further contain binders or other additives.

[0038] <Solid electrolyte layer> The solid electrolyte layer 20 is located between the positive electrode layer 10 and the negative electrode layer 40 and has the function of conducting the charge transfer medium between the positive electrode layer 10 and the negative electrode layer 40. In the laminate 1, the solid electrolyte layer 20 is laminated on a layer composed of a positive electrode active material layer 11 and an insulating layer 15. The material constituting the solid electrolyte layer 20 is not particularly limited as long as it has conductivity as a charge transfer medium, but examples include sulfide-based solid electrolyte materials, oxide-based solid electrolyte materials, nitride-based solid electrolyte materials, or halide-based solid electrolyte materials. As the sulfide-based solid electrolyte material, for example, a sulfide-based solid electrolyte material formed from a raw material composition containing Li2S and P2S5 can be used, and may have an argyrodite-type crystal structure.

[0039] Examples of oxide-based solid electrolyte materials include NASICON-type oxides, garnet-type oxides, or perovskite-type oxides. Examples of NASICON-type oxides include Li 1.5 Al 0.5 Ti 1.5 Examples of oxides containing Li, Al, Ti, P, and O include (PO4)3). Garnet-type oxides include, for example, Li7La3Zr2O 12 Examples of oxides containing Li, La, Zr, and O include those mentioned above. Examples of perovskite-type oxides include those containing Li, La, Ti, and O, such as LiLaTiO3.

[0040] The solid electrolyte layer 20 may further contain a binder, and such a binder can be one known to be used in the field of solid electrolyte layers for all-solid-state batteries. Examples of binder materials include polyvinylidene fluoride (PVdF), polymethyl methacrylate (PMMA), polyisobutene (PIB), styrene-butadiene rubber (SBR), polyethylene-vinyl acetate copolymer (PEVA), nitrile rubber (NBR), and hydrogenated nitrile rubber (HNBR). These may be used individually or in combination of two or more.

[0041] In one embodiment, the material of the solid electrolyte layer 20 is preferably particulate, for example, preferably has a median diameter (D50) of 0.5 to 10 μm.

[0042] <Middle class> If the laminate 1 has an intermediate layer, the intermediate layer 30 is laminated between the solid electrolyte layer 20 and the negative electrode layer 40. The presence of the intermediate layer 30 suppresses the deposition of metal ions at the interface of the negative electrode layer 40, particularly the growth of dendrites, and improves interfacial adhesion.

[0043] The intermediate layer 30 preferably has voids that allow metal ions, such as lithium ions, which are electronically conductive and act as a charge transfer medium, to pass through. Because the intermediate layer 30 has voids, when the all-solid-state battery is charged, metal ions moving from the solid electrolyte layer 20 towards the negative electrode layer 40 pass through the intermediate layer 30 and precipitate on the surface of the negative electrode layer 40 on the intermediate layer 30 side. By allowing the ions to pass through the intermediate layer 30, a uniform metal deposition layer can be formed on the surface of the negative electrode layer 40. Furthermore, because of the voids, the intermediate layer 30 can absorb changes in the thickness of the negative electrode layer 40 during charging and discharging within a certain range. Therefore, interfacial adhesion can be maintained even after repeated charging and discharging of the all-solid-state battery.

[0044] The porosity of the intermediate layer 30 is preferably higher than that of the solid electrolyte layer 20. This allows for the formation of more voids within the intermediate layer 30 through which metal ions can pass, thus enabling more uniform deposition of metal on the surface of the negative electrode layer 40. Furthermore, the intermediate layer 30 becomes more flexible, improving its ability to absorb changes in the thickness of the negative electrode layer 40. The porosity of the intermediate layer 30 can be, for example, 40-70%.

[0045] In one embodiment, the thickness of the intermediate layer 30 may be 5 μm or less, 3 μm or less, or within the range of 1 to 3 μm. Having such a thickness in the intermediate layer 30 can greatly reduce the frequency of direct contact between the solid electrolyte layer 20 and the deposited metal, thereby suppressing local degradation and current concentration of the solid electrolyte layer 20, and improving cycle characteristics and storage characteristics.

[0046] The intermediate layer 30 is preferably formed from amorphous carbon and metal nanoparticles. The intermediate layer 30 may also contain a binder as a binding agent to maintain its structure.

[0047] Amorphous carbon is less likely to alloy with metals such as lithium, thus suppressing dendrite formation and potentially improving the cycle characteristics of all-solid-state batteries. Amorphous carbon may be easily graphitizable carbon (also called soft carbon) or difficult-to-graphitize carbon (also called hard carbon). Furthermore, amorphous carbon may be any allotrope of carbon that does not exhibit a clear crystalline state, and may even be an aggregate of fine graphite crystals. Examples of amorphous carbon include carbon blacks such as acetylene black, furnace black, or Ketjen black, as well as coke, activated carbon, CNTs (carbon nanotubes), fullerenes, or graphene.

[0048] Examples of metal nanoparticles include tin (Sn), silicon (Si), zinc (Zn), magnesium (Mg), gold (Au), platinum (Pt), palladium (Pd), silver (Ag), aluminum (Al), bismuth (Bi), or antimony (Sb). The content of metal nanoparticles is preferably greater than 0% by mass and 30% by mass or less relative to the mass of the intermediate layer 30. The inclusion of metal nanoparticles in the intermediate layer 30 enhances its electronic conductivity and allows for more uniform metal deposition. Furthermore, because metal nanoparticles have a higher Young's modulus compared to amorphous carbon, the structure of the intermediate layer 30 can be maintained even when subjected to high-pressure pressing during the manufacturing of all-solid-state batteries.

[0049] The particle size of amorphous carbon and metal nanoparticles is preferably smaller than the particle size of the solid electrolyte material. This allows the intermediate layer 30 to fit into the gaps between the solid electrolyte materials constituting the interface of the solid electrolyte layer 20, thereby increasing the contact area between the solid electrolyte layer 20 and the intermediate layer 30 and improving adhesion. The particle size of amorphous carbon may be, for example, in the range of 0.02 to 0.10 μm in median diameter (D50), and the particle size of metal nanoparticles may be, for example, in the range of 0.02 to 0.20 μm in median diameter (D50).

[0050] The binder of the intermediate layer 30 is preferably capable of improving the adhesion between the particles constituting the intermediate layer 30 and between the intermediate layer 30 and the solid electrolyte layer 20. There are no particular restrictions on the binder, and those generally used in all-solid-state batteries can be used. Examples of materials for the binder of the intermediate layer 30 include acrylic acid polymers, cellulose polymers, styrene polymers, vinyl acetate polymers, urethane polymers, fluoroethylene polymers, or PVDF polymers.

[0051] <Negative electrode current collector> The negative electrode current collector 42, together with the negative electrode active material layer 41, constitutes the negative electrode layer 40. In one embodiment of the present invention, the negative electrode active material layer 41 is laminated on the solid electrolyte layer 20, and the negative electrode current collector 42 is laminated on the negative electrode active material layer 41. In another embodiment of the present invention, the negative electrode active material layer 41 is laminated on an intermediate layer 30 laminated on the solid electrolyte layer 20, and the negative electrode current collector 42 is laminated on the negative electrode active material layer 41. The shape of the negative electrode current collector 42 can be a plate or a foil.

[0052] The negative electrode current collector 42 is not particularly limited as long as it functions as a current collector in the negative electrode layer 40, and any negative electrode current collector known for its own use in all-solid-state batteries may be applied. The materials that make up the negative electrode current collector 42 include nickel, copper, or stainless steel, with copper being preferred.

[0053] <Negative electrode active material layer> The negative electrode active material layer 41 has the function of intercalating and releasing lithium ions. The material constituting the negative electrode active material layer 41 can be a material known for its use in the negative electrode active material layer of all-solid-state batteries. Examples of negative electrode active materials include metallic lithium, lithium alloys, metal oxides, metal sulfides, metal nitrides, Si, SiO, or carbon materials. Examples of carbon materials include artificial graphite, natural graphite, hard carbon, or soft carbon. When metallic lithium or a lithium alloy is used as the negative electrode active material, metallic lithium may be deposited on the surface of the negative electrode current collector 42 by charging the all-solid-state battery. Alternatively, a metal that forms an alloy with lithium may be laminated on the surface of the negative electrode current collector 42, and a lithium alloy layer can be formed on the surface of the negative electrode current collector 42 by charging the all-solid-state battery. Examples of metals that form an alloy with lithium include magnesium, silicon, gold, silver, indium, germanium, tin, lead, aluminum, or zinc.

[0054] The negative electrode active material layer 41 may further contain a conductive additive or binder, if necessary. As the conductive additive or binder, those known for use in the negative electrode active material layer of all-solid-state batteries can be applied.

[0055] In one embodiment, at least a portion of either end of the negative electrode current collector 42 in the X direction may extend in the X direction to form a negative electrode tab (not shown), and at least a portion of either end of the positive electrode current collector 12 in the X direction may extend in the X direction to form a positive electrode tab (not shown). Preferably, the negative electrode tab and the positive electrode tab extend in opposite directions to each other in the X direction. With this configuration, when multiple laminates 1 are stacked, it becomes easy to connect the positive and negative electrodes in parallel.

[0056] Figure 2 shows a cross-sectional view taken along the line A-A' in Figure 1. The line A-A' in Figure 1 may be a straight line parallel to the X direction, passing through the center of the main surface of the laminate 1 in a plan view, for example, the main surface of the negative electrode current collector 42. Figure 3 shows a cross-sectional view taken along the line B-B' in Figure 1. The line B-B' in Figure 1 may be a straight line parallel to the Y direction, passing through the center of the main surface of the laminate 1 in a plan view, for example, the main surface of the negative electrode current collector 42. In this specification, the center of the main surface of the laminate 1 in plan view can be defined, for example, as the position of the intersection of a straight line parallel to the Y direction and passing through the midpoint of a line segment whose two ends are the ends of the layer, which lies on a straight line parallel to the X direction and exists on the main surface of the layer, and which lies on a straight line parallel to the X direction, and a straight line parallel to the X direction and passing through the midpoint of a line segment whose two ends are the ends of the layer, which lies on a straight line parallel to the Y direction and exists on the main surface of the layer.

[0057] The dimensional design of each layer constituting the laminate 1 will be described below based on Figures 2 and 3. In the present invention, it is preferable that the relationships of each layer shown in Figure 2 or Figure 3 are satisfied in the cross-section in the stacking direction, which is defined by an arbitrary straight line passing through the center of the main surface in a plan view of the laminate 1. By arranging each layer constituting the laminate 1 in this manner, short circuits between the positive electrode layer and the negative electrode layer can be suppressed at any end of each layer, even when charging and discharging are repeated.

[0058] In the laminate 1, the difference between the shortest distance from the center in the longitudinal direction (X direction) of the negative electrode active material layer 41 to one end (the left end in Figure 2) and the shortest distance from the center in the longitudinal direction (X direction) of the positive electrode active material layer 11 to the end in the same direction as the end of the negative electrode active material layer 41 (the left end in Figure 2) is defined as a, the difference between the shortest distance from the center in the longitudinal direction (X direction) of the solid electrolyte layer 20 to the end in the same direction as the end of the negative electrode active material layer 41 (the left end in Figure 2) and the shortest distance from the center in the longitudinal direction of the positive electrode active material layer 11 to the end in the same direction as the end of the negative electrode active material layer 41 (the left end in Figure 2) is defined as b, the difference between the shortest distance from the center in the longitudinal direction (X direction) of the positive electrode active material layer 11 to the outer end of the insulating layer 15 in the same direction as the end of the negative electrode active material layer 41 (the left end in Figure 2) and the shortest distance from the center in the longitudinal direction (X direction) of the positive electrode active material layer 11 to the end in the same direction as the end of the negative electrode active material layer 41 (the left end in Figure 2) is defined as c, and the thickness of the solid electrolyte layer 20 at the aforementioned end of the solid electrolyte layer 20 is defined as t s , the thickness of the insulating layer 15 at the aforementioned outer end of the insulating layer 15 is defined as t p , and the voltage during discharge is defined as d(V), the respective layers are configured so as to satisfy the relationship a<b<c and satisfy the relationship c-b+t s +t p >0.2 / 12×d.

[0059] As shown in Figure 2, the difference a between the shortest distance from the center of the negative electrode active material layer 41 in the longitudinal direction (X direction) to one end (the left end in Figure 2) and the shortest distance from the center of the positive electrode active material layer 11 in the longitudinal direction (X direction) to the end of the negative electrode active material layer 41 in the same direction (the left end in Figure 2) corresponds to the overhang length (a) of the negative electrode active material layer 41 from the end of the positive electrode active material layer 11 to the end of the negative electrode active material layer 41. The difference b between the shortest distance to the end in the same direction (the left end in Figure 2) corresponds to the overhang length (b) of the solid electrolyte layer 20 from the end of the positive electrode active material layer 11 to the end of the solid electrolyte layer 20. The difference c between the shortest distance from the center of the positive electrode active material layer 11 in the longitudinal direction (X direction) to the outer end of the insulating layer 15 in the same direction as the end of the negative electrode active material layer 41 (the left end in Figure 2) and the shortest distance from the center of the positive electrode active material layer 11 in the longitudinal direction (X direction) to the end in the same direction as the end of the negative electrode active material layer 41 (the left end in Figure 2) corresponds to the overhang length (c) of the insulating layer 15 from the end of the positive electrode active material layer 11 to the outer end of the insulating layer 15.

[0060] By configuring these to satisfy the relationship a<b<c, it is possible to suppress the metal deposited on the negative electrode layer 40 from wrapping around and accumulating at the end portion of the solid electrolyte 20 even after repeated charge and discharge cycles, and thereby suppress local side reactions caused by contact between the deposited metal and the solid electrolyte 20. In contrast, if the aforementioned a, b, and c are configured to satisfy the relationship b<a<c, metal deposition, particularly dendrite growth, occurs in the negative electrode layer 40, and when these come into contact with the solid electrolyte 20, local side reactions occur, leading to an increase in the internal resistance of the battery, or local structural destruction of the solid electrolyte 20. As a result, the deposited metal intrudes into the destroyed structural portion to further promote dendrite growth, which increases the risk of short circuit between the positive electrode layer and the negative electrode layer, and may also degrade the cycle characteristics. On the other hand, if the aforementioned a, b, and c are configured to satisfy the relationship a<c≦b, burrs are likely to be generated at the end portion of the solid electrolyte 20 during the production of the laminate 1, and as charge and discharge are repeated, the risk of promoting the deposition of metal ions at the end portions of the solid electrolyte layer 20 and the like, particularly the growth of dendrites, increases, while the creepage distance from the negative electrode active material layer 41 to the positive electrode current collector 12, which will be described later, decreases, thereby increasing the risk of short circuit between the positive electrode layer and the negative electrode layer.

[0061] In the laminate 1, c-b+t s +t p corresponds to the creepage distance from the negative electrode active material layer 41 to the positive electrode current collector 12. The larger the creepage distance, the greater the distance from the negative electrode layer 40 to the positive electrode current collector 12 even when metal is deposited on the negative electrode layer 40, so that the possibility of the deposited metal reaching the positive electrode current collector 12 and causing a short circuit can be reduced. On the other hand, the amount of metal deposited on the negative electrode layer 40 tends to increase as the discharge voltage of the all-solid-state battery increases. Therefore, in order to prevent short circuits, it is necessary to consider the discharge voltage of the all-solid-state battery when determining the aforementioned creepage distance. The present inventor focused on the relationship between the discharge voltage d(V) of such an all-solid-state battery and the aforementioned creepage distance, and found that the creepage distance (c-b+t s +t p ) is c-b+t s +t pWe found that if the configuration satisfies the relationship >0.2 / 12 × d, short circuits between the positive and negative electrode layers can be suppressed. That is, according to JIS C 0704-1995, the creepage distance required for insulation at a voltage of 12 (V) is 0.2 mm, and since there can be a linear relationship between voltage and insulation creepage distance, we calculated the product of the discharge voltage d (V) of the all-solid-state battery according to the present invention and the creepage distance per unit voltage (0.2 / 12) (mm / V) derived from JIS C 0704-1995, and the creepage distance according to the present invention (c-b+t s +t p We found that by making )(mm) larger than the above product, short circuits between the positive electrode layer and the negative electrode layer can be suppressed. Here, the voltage can be the so-called open-circuit voltage. In one embodiment, the open-circuit voltage used in the present invention is the open-circuit voltage immediately after full charge at the initial stage of manufacturing of the all-solid-state battery according to the present invention. In another embodiment, the open-circuit voltage used in the present invention is the open-circuit voltage immediately after full charge at any stage of use of the all-solid-state battery according to the present invention.

[0062] The open-circuit voltage of the all-solid-state battery targeted in this invention can be adjusted by appropriately changing the material, size, or manufacturing conditions of each layer constituting the laminate 1. Furthermore, it can be confirmed through one to several prototypes.

[0063] In the laminate 1, the creepage distance (c-b+t s +t p The larger the creepage distance, the greater the effect of suppressing short circuits between the positive and negative electrode layers. Therefore, from the viewpoint of suppressing short circuits, there is no particular upper limit to the creepage distance. However, for all-solid-state batteries, compact size is generally required for the same electrical capacity. Therefore, the upper limit of the creepage distance can be set as, if necessary, by adding 0.1 to 5 mm, 0.1 to 3 mm, or 0.1 to 2 mm to the value of 0.2 / 12 × d (mm).

[0064] In one embodiment, in the laminate 1, b, c and t s However, cb>ts The structure is configured to satisfy the following relationship. The cb corresponds to the overhang length of the insulating layer 15 from the edge of the solid electrolyte layer 20 to the outer edge of the insulating layer 15. As shown in Figure 4, as the length of the cb decreases, the burrs generated on the solid electrolyte layer 20 tend to become significantly larger. Therefore, by adjusting the length of the cb to a constant length, the burrs generated on the solid electrolyte layer 20 during manufacturing can be efficiently suppressed. The inventors have determined that the thickness t of the edge of the solid electrolyte layer 20 s Focusing on the fact that the larger cb > t, the greater the elongation deformation of the solid electrolyte layer 20, and the greater the height of the resulting burr, we considered that cb > t s We found that by configuring the battery to satisfy the given relationship, the generation of burrs at the edges of the solid electrolyte layer 20 can be efficiently suppressed during the manufacturing of the all-solid-state battery. As a result, in such an all-solid-state battery, even after repeated charging and discharging, the deposition of metal at the edges of the solid electrolyte layer 20, particularly the growth of dendrites, can be suppressed, and short circuits between the positive electrode layer 10 and the negative electrode layer 40, as well as localized side reactions in the solid electrolyte layer 20, can be further suppressed.

[0065] In the laminate 1, the greater the overhang length (cb) of the insulating layer 15 from the edge of the solid electrolyte layer 20 to the outer edge of the insulating layer 15, the greater the effect of suppressing the generation of burrs at the edges of the solid electrolyte layer 20, etc. Therefore, from the viewpoint of suppressing the generation of burrs, there is no particular upper limit to the overhang length (cb) of the insulating layer 15. However, in all-solid-state batteries, for the same electrical capacity, a compact size is generally required. Therefore, the upper limit of the overhang length (cb) of the insulating layer 15 may be set as the thickness t of the edge of the solid electrolyte layer 20, as needed. s The upper limit can be set by adding 0.1-5 mm, 0.1-3 mm, or 0.1-2 mm to the value of .

[0066] As described later, the laminate 1 is manufactured by pressing it under high pressure in the stacking direction. Therefore, considering the elongation rate of 1 (%) in the longitudinal direction (X direction) of the negative electrode active material layer 41 when pressed under high pressure during manufacturing, and when the length of the negative electrode active material layer 41 in the longitudinal direction (X direction) is e, the above a, b, and e are configured to satisfy the relationship b > a + (e × 0.01), thereby enabling the provision of an all-solid-state battery according to the present invention more accurately and / or stably.

[0067] In the laminate 1, the greater the overhang length (b) of the solid electrolyte layer 20 from the end of the positive electrode active material layer 11 to the end of the solid electrolyte layer 20, the easier it is to satisfy the relationship b>a+(e×0.01). Therefore, from the viewpoint of ease of manufacturing the target all-solid-state battery, there is no particular upper limit to the overhang length (b) of the solid electrolyte layer 20. However, for all-solid-state batteries, compact size is generally required for the same electrical capacity. Therefore, the upper limit of the overhang length (b) of the solid electrolyte layer 20 can be set as a value obtained by adding 0.1~5mm, 0.1~3mm, or 0.1~2mm to the value of a+(e×0.01), as needed.

[0068] The above is a description of the dimensional design for the left end in Figure 2. However, it goes without saying that it is preferable for the right end to be configured similarly from the viewpoint of suppressing short circuits between the positive and negative electrode layers and improving cycle characteristics. Note that a, b, c, and t are specified for the left and right ends, respectively. s , and t p If the corresponding values ​​are different from each other, the average value can be taken to determine whether or not it falls within the scope of the present invention.

[0069] Figure 3 shows a cross-section of the laminate 1 in a plan view, perpendicular to the cross-section in Figure 2. In Figure 3, a', b', c', t s ', and t p ' represents a, b, c, and t in Figure 2, respectively. s , and t pThese are the corresponding values. From the viewpoint of suppressing short circuits between the positive and negative electrode layers and improving cycle characteristics, a', b', c', t s ', and t p The configuration that includes ' is a, b, c, t s , and t p It is preferable that the configuration satisfies a similar relationship to that of the configuration including. Also, in Figure 3, the left end and the right end, a', b', c', t s ', and t p If the values ​​corresponding to ' are different from each other, the average value can be taken to determine whether or not it falls within the scope of the present invention.

[0070] Also, Figure 2 a, b, c, t s , and t p The corresponding values ​​are a', b', c', and t in Figure 3. s ', and t p The corresponding values ​​may be equal to each other. By having these values ​​equal, differences in the characteristics of the all-solid-state battery in different directions in a plan view can be suppressed.

[0071] In one embodiment, the laminate 1 is an all-solid-state battery housed in an outer casing (not shown). In this embodiment, a positive electrode tab extending from the positive electrode current collector 12 of the laminate 1 and a negative electrode tab extending from the negative electrode current collector 42 are configured to protrude from the outer casing, or the positive electrode current collector 12 and the negative electrode current collector 42 of the laminate 1 are connected to the positive electrode tab and the negative electrode tab, which are configured to protrude from the outer casing, within the outer casing. Since the thickness of the laminate 1 may change with charging and discharging, it is preferable that the outer casing be configured to accommodate the change in the thickness of the laminate 1. A laminate film can be used as the material for the outer casing. An example of the laminate film is a three-layer laminate film in which an inner resin layer, a metal layer, and an outer resin layer are laminated in that order from the inside. The outer resin layer may be, for example, a polyamide (also called nylon) layer or a polyethylene terephthalate (PET) layer, the metal layer may be, for example, an aluminum layer, and the inner resin layer may be, for example, a polyethylene layer or a polypropylene layer. It is preferable that each layer of the laminate film is integrated by adhesive, heat, or pressure.

[0072] In one embodiment, the all-solid-state battery housed in the outer casing may be further held by a restraining member so as to apply a restraining force in the stacking direction of the laminate 1. With such a configuration, changes in the thickness of the laminate 1 due to charging and discharging can be suppressed, and during charging, metal can be uniformly deposited on the surface of the negative electrode layer 40, thereby suppressing metal deposition, particularly dendrite growth. As such a restraining member, a restraining member known in the field of all-solid-state batteries can be applied. The restraining force by the restraining member is preferably, for example, 0.1 to 10 MPa.

[0073] In the laminate 1 shown in Figure 2, the positive electrode active material layer 11, solid electrolyte layer 20, intermediate layer 30, negative electrode active material layer 41, and negative electrode current collector 42 are stacked in the Z direction relative to the positive electrode current collector 12. However, in another embodiment, the laminate 2 may be formed in which the positive electrode active material layer 11, solid electrolyte layer 20, intermediate layer 30, negative electrode active material layer 41, and negative electrode current collector 42 are further stacked in the -Z direction relative to the positive electrode current collector 12 of the laminate 1 in the laminate 2. That is, the laminate 2 may be a laminate in which the positive electrode active material layer 11, solid electrolyte layer 20, intermediate layer 30, negative electrode active material layer 41, and negative electrode current collector 42 are stacked in a generally plane-symmetric manner relative to the positive electrode current collector 12. In yet another embodiment, a solid-state battery may be formed by stacking multiple laminates 2 and housing them in the outer casing. The number of multiple laminates 2 may be 2 to 40, 10 to 40, or 20 to 30.

[0074] The multiple positive electrode current collectors 12 and negative electrode current collectors 42 present in the multiple stacked bodies 2 housed in the outer casing are connected in parallel inside the outer casing, and are further connected to positive electrode tabs and negative electrode tabs configured to protrude from the outer casing, respectively. Furthermore, the all-solid-state battery, including the multiple stacked bodies 2 housed in the outer casing, may be further held by a restraining member so as to apply a restraining force in the stacking direction of the multiple stacked bodies 2.

[0075] A configuration in which multiple stacked units 2 are stacked and housed in the outer casing is sometimes referred to as a cell of an all-solid-state battery. Such cells can be used individually or in multiples connected in parallel or series, as needed.

[0076] <Method for manufacturing laminates> The laminate 1 can be manufactured by applying methods known in the field of all-solid-state batteries and adjusting each layer to conform to the dimensional design described above. For example, the laminate 1 can be manufactured by a method including a positive electrode layer preparation step, a solid electrolyte layer formation step, an intermediate layer formation step, and a negative electrode layer formation step. In embodiments where the laminate 1 does not include an intermediate layer, the intermediate layer formation step can be omitted.

[0077] The positive electrode layer preparation process is a process for preparing the positive electrode layer 10. The positive electrode layer 10 can be manufactured, for example, by forming a positive electrode active material layer 11 on the surface of the positive electrode current collector 12. As a method for forming the positive electrode active material layer 11, a method of applying a slurry containing the components of the positive electrode active material layer and drying it can be applied. As the slurry containing the components of the positive electrode active material layer, a dispersion of the positive electrode active material containing a solvent, positive electrode active material, and optionally a conductive additive or binder can be used. In the positive electrode layer preparation step, it is preferable to arrange an insulating layer 15 so as to surround the outer periphery of the positive electrode active material layer 11.

[0078] The solid electrolyte layer formation step is a step of forming a solid electrolyte layer 20 on the surface of the positive electrode active material layer 11 of the positive electrode layer 10. As a method for forming the solid electrolyte layer 20, a slurry containing the components of the solid electrolyte layer can be directly applied to the surface of the positive electrode active material layer 11 and dried, or a slurry containing the components of the solid electrolyte layer can be applied to the surface of a separately prepared support sheet and dried to form the solid electrolyte layer 20, which can then be transferred to the surface of the positive electrode active material layer 11 under a specific pressure. As the slurry containing the components of the solid electrolyte layer, for example, a dispersion of the solid electrolyte containing a solvent, a solid electrolyte, and optionally a binder can be used. Furthermore, as a method for forming the solid electrolyte layer 20, a method can be applied in which the solid electrolyte layer is integrated with the substrate and made self-supporting before being placed on the positive electrode layer. As the substrate, for example, a nonwoven fabric or a woven fabric can be used. As the material of the substrate, a polyester resin such as PET can be used.

[0079] The intermediate layer formation step is a step of forming an intermediate layer 30 on the surface of the solid electrolyte layer 20 opposite to the positive electrode active material layer 11 side. As a method for forming the intermediate layer 30, a slurry containing the components of the intermediate layer can be directly applied to the surface of the solid electrolyte layer 20 and dried, or a slurry containing the components of the intermediate layer can be applied to the surface of a separately prepared support sheet and dried to form the intermediate layer 30, which can then be transferred to the surface of the solid electrolyte layer 20 under a specific pressure. As the slurry containing the components of the intermediate layer, for example, a dispersion of an intermediate layer-forming material containing a solvent, metal nanoparticles, amorphous carbon, and optionally a binder can be used.

[0080] The negative electrode layer formation step is a step of forming a negative electrode layer 40 on the surface of the intermediate layer 30 opposite to the solid electrolyte layer 20 side. The negative electrode layer 40 can be manufactured, for example, by forming a negative electrode active material layer 41 on the surface of the intermediate layer 30 and laminating a negative electrode current collector 42 on the surface of the negative electrode active material layer 41. As a method for forming the negative electrode active material layer 41 on the surface of the intermediate layer 30, a slurry containing the components of the negative electrode active material layer can be applied to the surface of the intermediate layer 30 and dried, or a slurry containing the components of the negative electrode active material layer can be applied to the surface of a separately prepared support sheet and dried to form the negative electrode active material layer 41, which can then be transferred to the surface of the intermediate layer 30 under a specific pressure. As the slurry containing the components of the negative electrode active material layer, a dispersion of the negative electrode active material containing a solvent, negative electrode active material, and optionally a conductive additive or binder can be used. The negative electrode layer 40 can be manufactured by laminating a negative electrode current collector 42 onto the surface of the negative electrode active material layer 41 formed as described above. If the laminate 1 does not include an intermediate layer 30, the negative electrode active material layer 41 can be formed on the surface of the solid electrolyte layer 20 instead of the surface of the intermediate layer 30.

[0081] The intermediate layer formation process and the negative electrode layer formation process may be performed simultaneously. For example, the intermediate layer 30 of an intermediate layer-negative electrode layer laminate, in which the intermediate layer 30 and the negative electrode layer 40 are pre-integrated and self-supporting, may be laminated onto the surface of the solid electrolyte layer 20. The intermediate layer-negative electrode layer laminate can be manufactured, for example, by pre-forming a negative electrode active material layer 41 on the surface of the negative electrode current collector 42, applying a slurry containing the components of the intermediate layer to the surface of the negative electrode active material layer 41, and drying it to form the intermediate layer 30.

[0082] As a method for forming a negative electrode active material layer 41 on the surface of the negative electrode current collector 42, one can apply a slurry containing the components of the negative electrode active material layer to the surface of the negative electrode current collector 42 and dry it, or apply a slurry containing the components of the negative electrode active material layer to the surface of a separately prepared support sheet and dry it, and then transfer the formed negative electrode active material layer 41 to the surface of the negative electrode current collector 42 under a specific pressure. Furthermore, when metallic lithium or a lithium alloy is used as the negative electrode active material layer 41, the negative electrode current collector 42 is laminated on the surface of the solid electrolyte layer 20 or the intermediate layer 30 such that it has a negative electrode current collector 42, or a metallic layer that forms an alloy with lithium at the interface between the negative electrode current collector 42 and the solid electrolyte layer 20 or the intermediate layer 30. During charging of the all-solid-state battery, metallic lithium can be deposited on the surface of the negative electrode current collector 42, or a lithium alloy layer can be formed.

[0083] Each step can be adjusted to achieve the dimensional design of each layer in the laminate 1 described above.

[0084] As described above, a laminate 1 can be manufactured in which the positive electrode layer 10, the solid electrolyte layer 20, the intermediate layer 30, and the negative electrode layer 40 are stacked in this order. The resulting laminate 1 can be pressed in any direction to increase its density. Furthermore, the method of pressing is not limited to after the laminate 1 has been formed, and pressing can be performed at any step of the process described above. This allows the surface to be laminated to be flattened before other layers are stacked, thereby improving product accuracy.

[0085] A laminate, such as laminate 2, in which each layer is stacked in the Z-direction and -Z-direction of the positive electrode current collector 12, can be manufactured by forming each layer simultaneously or sequentially on both sides of the positive electrode current collector 12. Preferably, each layer is formed by transferring a layer formed on the surface of a separately prepared support sheet to the surface to be laminated with a specific pressure.

[0086] When the laminate 1 or 2 is housed in an outer casing to produce a product, it can be manufactured, for example, as follows: One end of the positive electrode tab is connected to the positive electrode current collector 12 of the obtained laminate 1 or 2, and one end of the negative electrode tab is connected to the negative electrode current collector 42. Next, the laminate 1 or 2 is housed in the outer casing such that the other ends of the positive electrode tab and the negative electrode tab protrude from the outer casing, and the outer casing is sealed. Then, a restraining member is optionally placed on the outer surface of the outer casing to restrain the laminate 1 or 2 with a specific restraining force. Furthermore, when stacking multiple laminates 2 and housing them in an outer casing to create a product, the multiple laminates 2 can be stacked and housed in the outer casing using methods that are known in the field of all-solid-state batteries. Multiple positive electrode current collectors 12 of the multiple laminates 2 are connected to one end of the positive electrode tab, and multiple negative electrode current collectors 42 are connected to one end of the negative electrode tab. Then, the stacked multiple laminates 2 are housed in the outer casing so that the other ends of the positive electrode tab and negative electrode tab protrude from the outer casing, and the outer casing is sealed. Then, a restraining member is optionally placed on the outer surface of the outer casing to restrain the stacked multiple laminates 2 with a specific restraining force.

[0087] While embodiments of the present invention have been described above, it should be understood that these are illustrative and should not be considered limiting. Additions, omissions, substitutions, and other modifications can be made without departing from the scope of the invention. Therefore, the present invention should not be considered limited by the foregoing description, but rather limited by the claims. [Explanation of Symbols]

[0088] 1. Stacked solid-state battery 10 Positive electrode layer 11 Cathode active material layer 12 Positive electrode current collector 15. Insulating layer (insulating frame) 20 Solid electrolyte layer 30 Middle Class 40 Negative electrode layer 41 Negative electrode active material layer 42 Negative electrode current collector

Claims

1. It includes a positive electrode current collector, a positive electrode active material layer, an insulating layer, a solid electrolyte layer, a negative electrode active material layer, and a negative electrode current collector. The all-solid-state battery comprises a laminate in which the positive electrode current collector, the positive electrode active material layer, the solid electrolyte layer, the negative electrode active material layer, and the negative electrode current collector are stacked in this order, and the insulating layer is arranged to circle the outer periphery of the positive electrode active material layer, In a plan view, each layer of the laminate is configured such that the outer periphery of the positive electrode active material layer, the outer periphery of the negative electrode active material layer, the outer periphery of the solid electrolyte layer, and the outer periphery of the insulating layer are outward in this order. In a cross-section parallel to the stacking direction, passing through a straight line parallel to the longitudinal direction of the laminate, Let a be the difference between the shortest distance from the center of the negative electrode active material layer in the longitudinal direction to one end and the shortest distance from the center of the positive electrode active material layer in the longitudinal direction to the end of the negative electrode active material layer in the same direction as the end. Let b be the difference between the shortest distance from the center of the solid electrolyte layer in the longitudinal direction to the end of the negative electrode active material layer in the same direction as the end, and the shortest distance from the center of the positive electrode active material layer in the longitudinal direction to the end of the negative electrode active material layer in the same direction as the end. Let c be the difference between the shortest distance from the center of the positive electrode active material layer in the longitudinal direction to the outer edge of the insulating layer in the same direction as the edge of the negative electrode active material layer, and the shortest distance from the center of the positive electrode active material layer in the longitudinal direction to the edge of the negative electrode active material layer in the same direction as the edge. The thickness of the solid electrolyte layer at the end of the solid electrolyte layer is t ｓ year, The thickness of the insulating layer at the outer edge of the insulating layer is t ｐ year, When the voltage during discharge is d (V), The relationship a < b < c is satisfied, and c - b + t ｓ +t ｐ An all-solid-state battery configured to satisfy the relationship > 0.2 / 12 × d.

2. The all-solid-state battery according to claim 1, comprising a laminate further having an intermediate layer between the negative electrode active material layer and the solid electrolyte layer, wherein, in a plan view of the laminate, the outer peripheral edge of the intermediate layer is located outside the outer peripheral edge of the negative electrode active material layer and is at the same position as, or inside, the outer peripheral edge of the solid electrolyte layer.

3. The aforementioned b, c and t ｓ However, c-b > t ｓ A solid-state battery according to claim 1 or 2, configured to satisfy the relationship.

4. The all-solid-state battery according to claim 1 or 2, wherein when e is the distance from one end to the other end in the longitudinal direction of the negative electrode active material layer, a, b and e are configured such that b > a + (e × 0.01).

5. In a cross-section parallel to the stacking direction, passing through a straight line parallel to the short direction of the laminate, Let a' be the difference between the shortest distance from the center of the negative electrode active material layer in the short direction to one end and the shortest distance from the center of the positive electrode active material layer in the short direction to the end of the negative electrode active material layer in the same direction as the end. Let b' be the difference between the shortest distance from the center of the solid electrolyte layer in the short direction to the end of the negative electrode active material layer in the same direction as the end, and the shortest distance from the center of the positive electrode active material layer in the short direction to the end of the negative electrode active material layer in the same direction as the end. Let c' be the difference between the shortest distance from the center of the positive electrode active material layer in the short direction to the outer edge of the insulating layer in the same direction as the edge of the negative electrode active material layer, and the shortest distance from the center of the positive electrode active material layer in the short direction to the edge of the negative electrode active material layer in the same direction as the edge. The thickness of the solid electrolyte layer at the end of the solid electrolyte layer is t ｓ 'year, The thickness of the insulating layer at the outer edge of the insulating layer is t ｐ 'year, When the voltage during discharge is d (V), satisfy the relationship of a' < b' < c', and c'-b'+t ｓ '+t ｐ '> 0.2 / 12×d, the all-solid-state battery according to claim 1 or 2.

6. The above b', c' and t ｓ 'but, c'-b'>t ｓ The all-solid-state battery according to claim 5, configured to satisfy the relationship '.

7. The all-solid-state battery according to claim 5, wherein when e' is the distance from one end to the other end in the short direction of the negative electrode active material layer, a', b', and e' are configured such that b' > a' + (e' × 0.01).

8. Said a, b, c, t ｓ and t ｐ However, the above a', b', c', t ｓ 'and t ｐ The all-solid-state battery according to claim 5, wherein each of the two is the same size.

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