All-solid-state secondary battery and method for manufacturing all-solid-state secondary battery

Abstract

This all-solid-state secondary battery comprises: a laminate having a positive electrode, a negative electrode, and a solid electrolyte layer interposed between the positive electrode and the negative electrode; a buffer member that wraps a cell assembly in which a plurality of laminates are stacked, and to which a positive electrode power supply plate connected to a plurality of positive electrodes and a negative electrode power supply plate connected to a plurality of negative electrodes are attached; a bottomed cylindrical battery can that accommodates the cell assembly wrapped by the buffer member; and a can lid part that has an electrode terminal and seals an opening at one end of the battery can. The inner side of the buffer member is brought into contact with the side surface of the cell assembly, and the outer side of the buffer member is brought into contact with the inner side of the battery can. A part of the positive electrode power supply plate is provided with a positive electrode expansion / contraction part disposed between the cell assembly and the can lid part and connected to the electrode terminal, and a part of the positive electrode power supply plate is disposed between the cell assembly and the buffer member. A part of the negative electrode power supply plate is provided with a negative electrode expansion / contraction part disposed between the cell assembly and the bottom surface of the battery can, and a part of the negative electrode power supply plate is disposed between the cell assembly and the buffer member.

Description

All-solid-state secondary battery and method for manufacturing all-solid-state secondary battery

[0001] The present invention relates to an all-solid-state secondary battery and a method for manufacturing an all-solid-state secondary battery.

[0002] Conventionally, lithium secondary batteries, particularly lithium-ion secondary batteries, have been used in portable electronic devices such as mobile phones or notebook computers, and in electric vehicles. Lithium-ion batteries contain an organic solvent, which is a flammable substance, as a non-aqueous electrolyte.

[0003] With the development of the above-mentioned devices and electric vehicles, the energy density of lithium-ion secondary batteries has increased, and the amount of the organic solvent (electrolyte solution), which is a flammable substance, has tended to increase. As a result, higher reliability is required for lithium-ion secondary batteries.

[0004] In such a situation, all-solid-state lithium secondary batteries (all-solid-state secondary batteries) that do not use an electrolyte solution have attracted attention. An all-solid-state secondary battery uses a molded body of a solid electrolyte without using an electrolyte solution instead of a conventional organic solvent-based electrolyte. That is, an all-solid-state secondary battery has a laminate in which a positive electrode layer, a negative electrode layer, and a solid electrolyte layer are laminated.

[0005] Since an electrolyte solution is not used in an all-solid-state secondary battery, it has the following advantages. That is, in an all-solid-state secondary battery, the electrolyte solution does not leak from the inside of the housing to the outside. In addition, in an all-solid-state secondary battery, since it is not necessary to consider the thermal expansion of the electrolyte solution due to high temperature, the heat-resistant temperature can be set to a high temperature. In addition, since it is not necessary to consider the deterioration of the electrolyte solution, an all-solid-state secondary battery can achieve a long life.

[0006] Patent Document 1 discloses a battery in which a laminate is housed in a space formed by a housing and a lid body. Patent Document 2 discloses a battery provided in a space formed by a housing and a lid body in a state where a single laminate is housed in a metal housing member.

[0007] Japanese Patent Application Laid-Open No. 2004-253287 International Publication No. 2023 / 171735

[0008] Since the laminate of the all-solid-state secondary battery is obtained by pressure-forming a powder material, it is fragile and may be damaged by impact. However, in the all-solid-state secondary battery, it is desired to further improve the impact resistance to withstand extremely high impacts while taking advantage of the above-described advantages such as heat resistance and long life.

[0009] As a means for solving the above problems, the technology described in the claims is used.

[0010] An all-solid-state secondary battery according to an embodiment includes a laminate having a positive electrode, a negative electrode, and a solid electrolyte layer interposed between the positive electrode and the negative electrode, a plurality of the laminates stacked, a positive electrode power supply plate connected to the power supply tabs of the positive electrodes of the plurality of laminates, a negative electrode power supply plate connected to the power supply tabs of the negative electrodes of the plurality of laminates, a cushioning material wrapping a cell assembly to which the positive electrode power supply plate and the negative electrode power supply plate are attached, a bottomed cylindrical battery can accommodating the cell assembly wrapped by the cushioning material, an electrode terminal, and a can lid portion sealing an opening at one end of the battery can. The inside of the cushioning material is in contact with the side surface of the cell assembly, and the outside of the cushioning material is in contact with the inside of the battery can. A positive electrode expansion and contraction portion is provided in a part of the positive electrode power supply plate, which is disposed between the cell assembly and the can lid portion and is connected to the electrode terminal, and a part of the positive electrode power supply plate is disposed between the cell assembly and the cushioning material. A negative electrode expansion and contraction portion is provided in a part of the negative electrode power supply plate, which is disposed between the cell assembly and the bottom surface of the battery can, and a part of the negative electrode power supply plate is disposed between the cell assembly and the cushioning material.

[0011] According to the present invention, the impact resistance of the all-solid-state secondary battery can be improved.

[0012] Figure 1 is an external perspective view of an all-solid-state secondary battery according to an embodiment. Figure 2 is a cross-sectional view of the all-solid-state secondary battery along line A-A in Figure 1. Figure 3A is a diagram illustrating the manufacturing process of the laminate. Figure 3B is a diagram illustrating the manufacturing process of the laminate. Figure 3C is an external perspective view of the laminate. Figure 3D is an external perspective view of the laminate. Figure 4 is an exploded perspective view of the cell assembly. Figure 5A is an external perspective view of the holder. Figure 5B is an external perspective view of the holder. Figure 6 is a diagram illustrating the process of attaching heat shrink tubing to the cell assembly. Figure 7A is an external perspective view of the cell assembly with heat shrink tubing attached. Figure 7B is an external perspective view of the cell assembly with heat shrink tubing attached. Figure 8A is an external perspective view of the cell assembly with cushioning material attached. Figure 8B is an external perspective view of the cell assembly with cushioning material attached. Figure 9 is a perspective view of the battery can containing the cell assembly. Figure 10 is an external perspective view of cushioning material in another example. Figure 11A is an external perspective view of the can lid. Figure 11B is an external perspective view of the can lid. Figure 12A is an external perspective view of the can lid with the positive electrode expandable portion joined. Figure 12B is a partial cross-sectional view illustrating the positive electrode expandable portion. Figure 12C is a partial cross-sectional view illustrating the bending of the positive electrode expandable portion. Figure 13A is a partial cross-sectional view illustrating the negative electrode expandable portion. Figure 13B is a partial cross-sectional view illustrating the bending of the negative electrode expandable portion. Figure 14A is a diagram illustrating the process of attaching the can lid to the battery can. Figure 14B is a diagram illustrating the process of attaching the can lid to the battery can. Figure 15 is a flowchart illustrating the manufacturing method of the all-solid-state secondary battery according to the first embodiment. Figure 16 is a cross-sectional view of the all-solid-state secondary battery according to the second embodiment. Figure 17A is an external perspective view of the laminate according to the second embodiment. Figure 17B is an external perspective view of the laminate according to the second embodiment. Figure 17C is an external perspective view of the laminate according to the second embodiment. Figure 18 is a cross-sectional view of the laminate according to the second embodiment. Figure 19 is an exploded perspective view of the cell assembly according to the second embodiment. Figure 20 is a flowchart illustrating the manufacturing method of the all-solid-state secondary battery according to the second embodiment. Figure 21 is an external perspective view of the all-solid-state secondary battery according to the third embodiment. Figure 22 is a cross-sectional view of the all-solid-state secondary battery along the line B-B in Figure 21.Figure 23 is a flowchart illustrating the manufacturing method of the all-solid-state secondary battery according to the third embodiment.

[0013] Embodiments of this disclosure will be described in detail below with reference to the drawings. In the drawings, the same parts are denoted by the same reference numerals in principle, and repeated descriptions are omitted. In the drawings, the representation of components may not show their actual location, size, shape, and extent in order to facilitate understanding of the invention.

[0014] <First Embodiment> The following describes the all-solid-state secondary battery according to the first embodiment. Figure 1 is an external perspective view of the all-solid-state secondary battery 1 according to the first embodiment. Figure 2 is a cross-sectional view of the all-solid-state secondary battery 1 along the line A-A in Figure 1. In the following description, the term "all-solid-state secondary battery" is used, but it may also be expressed as a stacked solid-state battery, battery module, etc.

[0015] The all-solid-state secondary battery 1 comprises a battery can 10, a cell assembly 21, a can lid 50, and a cushioning material 70. In the following description, the direction intersecting the bottom surface 101 of the battery can 10 and the can lid 50 is referred to as the first direction L1. In the first direction L1, the side with the bottom surface 101 is sometimes referred to as downward, and the side with the can lid 50 is sometimes referred to as upward. The first direction L1 is also sometimes referred to as the up-down direction.

[0016] [Battery Can 10] The battery can 10 is a cylindrical can with a closed bottom, with one end open and the other closed. Specifically, as shown in Figures 1 and 2, the battery can 10 is a cylindrical can formed in the shape of a closed bottom. Inside the battery can 10 are the cell assembly 21, positive electrode power supply plate 30, negative electrode power supply plate 40, and cushioning material 70, which will be described in detail later.

[0017] Furthermore, the battery can 10 is not limited to being a cylindrical can; it may be a rectangular can or other rectangular can with a cross-section, depending on the shape of the laminated body 20 housed inside. In other words, the battery can 10 only needs to be cylindrical.

[0018] The battery can 10 is formed of a conductive material, such as a metal material like stainless steel, aluminum, nickel alloy, etc. When the battery can 10 is electrically connected to the negative electrode or the positive electrode described later, the material of the battery can 10 may be selected so that corrosion of the battery can 10 and alteration of the material due to alloying with lithium ions do not occur.

[0019] [Cell assembly 21] The cell assembly 21 is housed inside the battery can 10 and has a laminate 20, a holder 22, a positive electrode current collector plate 30, and a negative electrode current collector plate 40.

[0020] [Laminate 20] The laminate 20 has an electrode body 211 in which a layer of a positive electrode 201, a layer of a negative electrode 202, and a solid electrolyte layer 203 are laminated. Specifically, the laminate 20 has an electrode body 211 in which the solid electrolyte layer 203 is interposed between the positive electrode 201 and the negative electrode 202 and laminated.

[0021] The positive electrode 201 is a columnar molded body (layer) in which a positive electrode mixture is pressure-molded by compression, rolling, etc. Note that the positive electrode 201 is not limited to a columnar layer and may be a prismatic layer. The positive electrode mixture is not particularly limited as long as it is, for example, a positive electrode active material used in a lithium ion secondary battery, that is, a material capable of occluding and releasing lithium ions. Specifically, LiM ｘ Mn ２－ｘ O ４ (However, M is at least one element selected from the group consisting of Li, B, Mg, Ca, Sr, Ba, Ti, V, Cr, Fe, Co, Ni, Cu, Al, Sn, Sb, In, Nb, Mo, W, Y, Ru, and Rh, and 0.01 ≦ x ≦ 0.5) spinel-type lithium manganese composite oxide represented by, Li ｘ Mn （１－ｙ－ｚ） Ni ｙ M ｚ O （２－ｋ） F ｌ (However, M is at least one element selected from the group consisting of Co, Mg, Al, B, Ti, V, Cr, Fe, Cu, Zn, Zr, Mo, Sn, Ca, Sr, and W, and 0.8 ≦ x ≦ 1.2, 0 < y < 0.5, 0 ≦ z ≦ 0.5, k + l < 1, -0.1 ≦ k ≦ 0.2, 0 ≦ l ≦ 0.1) layered compound represented by, LiCo １－ｘM ｘ O ２ Lithium cobalt composite oxide, LiNi, represented as (where M is at least one element selected from the group consisting of Al, Mg, Ti, Zr, Fe, Ni, Cu, Zn, Ga, Ge, Nb, Mo, Sn, Sb, and Ba, and 0 ≤ x ≤ 0.5) １－ｘ M ｘ O ２ Lithium nickel composite oxide, LiM (wherein M is at least one element selected from the group consisting of Al, Mg, Ti, Zr, Fe, Co, Cu, Zn, Ga, Ge, Nb, Mo, Sn, Sb, and Ba, and 0 ≤ x ≤ 0.5) １－ｘ N ｘ PO ４ (wherein M is at least one element selected from the group consisting of Fe, Mn, and Co, and N is at least one element selected from the group consisting of Al, Mg, Ti, Zr, Ni, Cu, Zn, Ga, Ge, Nb, Mo, Sn, Sb, and Ba, and 0 ≤ x ≤ 0.5) Olivine-type composite oxide, Li ４ Ti ５ O １２ Examples include lithium titanium composite oxides represented by [formula], and one of these may be used alone, or two or more may be used in combination.

[0022] The average particle size of the positive electrode active material is preferably 1 μm or more, more preferably 2 μm or more, preferably 10 μm or less, and more preferably 8 μm or less. The positive electrode active material may be primary particles or secondary particles formed by aggregation of primary particles. Using a positive electrode active material with an average particle size within the above range allows for a larger interface with the solid electrolyte, thereby improving the load characteristics of the battery.

[0023] The positive electrode active material preferably has a reaction-inhibiting layer on its surface to suppress its reaction with the solid electrolyte.

[0024] In a molded positive electrode mixture, direct contact between the positive electrode active material and the solid electrolyte can cause the solid electrolyte to oxidize, forming a resistance layer and potentially reducing the ionic conductivity within the molded body. By providing a reaction-inhibiting layer on the surface of the positive electrode active material to suppress its reaction with the solid electrolyte, direct contact between the positive electrode active material and the solid electrolyte can be prevented, thereby suppressing the reduction in ionic conductivity within the molded body due to oxidation of the solid electrolyte.

[0025] The reaction suppression layer should be composed of a material that has ionic conductivity and can suppress the reaction between the positive electrode active material and the solid electrolyte. Examples of materials that can constitute the reaction suppression layer include oxides containing Li and at least one element selected from the group consisting of Nb, P, B, Si, Ge, Ti, and Zr, more specifically, LiNbO ３ Nb-containing oxides such as Li ３ PO ４ Li ３ BO ３ Li ４ SiO ４ Li ４ GeO ４ LiTio ３ LiZrO ３ These are some examples. The reaction suppression layer may contain only one of these oxides, or it may contain two or more, and furthermore, multiple of these oxides may form a composite compound. Among these oxides, it is preferable to use an Nb-containing oxide, such as LiNbO ３ It is more preferable to use [this].

[0026] The reaction-inhibiting layer is preferably present on the surface in an amount of 0.1 to 1.0 part by mass per 100 parts by mass of the positive electrode active material. Within this range, the reaction between the positive electrode active material and the solid electrolyte can be effectively suppressed.

[0027] Methods for forming a reaction-inhibiting layer on the surface of the positive electrode active material include the sol-gel method, mechanofusion method, CVD method, and PVD method. The content of the positive electrode active material in the positive electrode mixture is preferably 60 to 95% by mass.

[0028] Examples of conductive additives for the positive electrode 201 include graphite (natural graphite, artificial graphite), graphene, carbon black, carbon nanofibers, carbon nanotubes, and other carbon materials. The content of the conductive additive in the positive electrode mixture is preferably 1 to 10% by mass.

[0029] The solid electrolyte of the positive electrode 201 can be one or more of the various sulfide-based solid electrolytes, hydride-based solid electrolytes, and oxide-based solid electrolytes described later, which can also be used for the negative electrode 202. To improve battery characteristics, it is desirable to include a sulfide-based solid electrolyte. The solid electrolyte content in the positive electrode mixture is preferably 4 to 30% by mass.

[0030] The positive electrode mixture may or may not contain a resin binder. Examples of resin binders include fluororesins such as polyvinylidene fluoride (PVDF) and acrylic resins. However, since the resin binder acts as a resistive component in the positive electrode mixture, it is desirable to keep its amount as small as possible. Therefore, it is preferable that the positive electrode mixture does not contain a resin binder, or if it does, its content is 0.5% by mass or less. It is more preferable that the resin binder content in the positive electrode mixture be 0.3% by mass or less, and even more preferable that it be 0% by mass (i.e., no resin binder is included).

[0031] When a current collector is used for the positive electrode 201, the current collector can be made of metal foil such as aluminum or stainless steel, perforated metal, mesh, expanded metal, foamed metal, carbon sheet, etc.

[0032] A molded positive electrode mixture can be formed, for example, by compressing a positive electrode mixture prepared by mixing a positive electrode active material, a conductive additive, a solid electrolyte, and a binder added as needed, using pressure molding or the like. Alternatively, a positive electrode mixture can be prepared by mixing the above-mentioned positive electrode mixture with a solvent, applying this to a substrate such as a current collector or a solid electrolyte layer 203 facing the positive electrode 201, drying it, and then pressing it to form a molded positive electrode mixture.

[0033] The thickness of the molded positive electrode mixture (in the case of a positive electrode 201 having the positive electrode mixture on the flow surface of the current collector, the thickness of the molded positive electrode mixture per side of the current collector; the same applies hereinafter) is preferably 200 μm or more from the viewpoint of increasing the battery capacity. Furthermore, the thickness of the molded positive electrode mixture is preferably 3000 μm or less, and more preferably 2000 μm or less, in order to reduce internal resistance.

[0034] The negative electrode 202 is a cylindrical molded body (layer) formed by pressure molding of the negative electrode mixture by compression or rolling. The negative electrode is not limited to a cylindrical layer, but may also be a prismatic layer. The negative electrode mixture can be constructed using negative electrode active materials used in lithium-ion secondary batteries. The negative electrode active material is not particularly limited as long as it is a material capable of intercalating and releasing lithium ions. Examples include: carbon-based materials capable of intercalating and releasing lithium such as graphite, pyrolytic carbons, cokes, glassy carbons, calcined organic polymer compounds, mesocarbon microbeads (MCMBs), and carbon fibers; elemental elements or oxides or alloys thereof that can form alloys with lithium such as Si, Sn, Ge, Bi, Sb, and In; nitrides containing lithium and transition metals such as Co, Ni, Mn, Fe, Cr, Ti, and W; metallic lithium; lithium alloys such as lithium-aluminum alloys; and lithium-containing transition metal oxides such as lithium niobium oxide and lithium titanium oxide. Examples of lithium titanium oxide include those represented by the following general composition formula (1): Li[Li １／３－ａ M １ ａ Ti ５／３－ｂ M ２ ｂ ]O ４ (1)

[0035] In general composition formula (1), M １ M is at least one element selected from the group consisting of Na, Mg, K, Ca, Sr, and Ba. ２ is at least one element selected from the group consisting of Al, V, Cr, Fe, Co, Ni, Zn, Ym, Zr, Nb, Mo, Ta, and W, where 0 ≤ a < 1 / 3 and 0 ≤ b ≤ 2 / 3.

[0036] In other words, in lithium titanium oxide represented by the general composition formula (1), some of the Li sites are element M １ It may be substituted with. However, in the general composition formula (1), element M １ The ratio of a is preferably less than 1 / 3. In lithium titanium oxide represented by general composition formula (1), Li is element M １ Since substitution with element M is not required, １ The value of 'a', which represents the ratio, can be 0.

[0037] Furthermore, in lithium titanium oxide represented by the general composition formula (1), element M ２ It is a component that enhances the electronic conductivity of lithium titanium oxide, and is element M ２ When b, which represents the ratio, is 0 ≤ b ≤ 2 / 3, the effect of improving electronic conductivity can be well ensured.

[0038] One or more of the materials exemplified above can be used as the negative electrode active material. For example, when lithium titanium oxide is used, a negative electrode active material other than lithium titanium oxide can also be used together with lithium titanium oxide. However, it is preferable that the proportion of negative electrode active material other than lithium titanium oxide in the total amount of negative electrode active material be 30% or less by mass.

[0039] The solid electrolyte for the negative electrode 202 is not particularly limited as long as it has lithium ion conductivity, and for example, sulfide-based solid electrolytes, hydride-based solid electrolytes, oxide-based solid electrolytes, etc., can be used.

[0040] Examples of sulfide-based solid electrolytes include Li ２ S-P ２ S ５ Li ２ S-SiS ２ Li ２ S-P ２ S ５ -GeS ２ Li ２ S-B ２ S ３ Examples include glass alloys, and in recent years, Li has attracted attention as a material with high lithium-ion conductivity. １０ GeP２ S １２ (LGPS system) and Li ６ PS ５ Cl (argyrodite type) can also be used. Among these, argyrodite type materials with particularly high lithium ion conductivity and high chemical stability are preferred.

[0041] Examples of hydride-based solid electrolytes include LiBH ４ , LIBH ４ Solid solutions of the following alkali metal compounds (e.g., LiBH) ４ Examples include those with a molar ratio of 1:1 to 20:1 between the solid solution and the alkali metal compound. Examples of alkali metal compounds in the solid solution include at least one selected from the group consisting of lithium halides (LiI, LiBr, LiF, LiCl, etc.), rubidium halides (RbI, RbBr, RbiF, RbCl, etc.), cesium halides (CsI, CsBr, CsF, CsCl, etc.), lithium amide, rubidium amide, and cesium amide.

[0042] Examples of oxide-based solid electrolytes include Li ７ La ３ Zr ２ O １２ , LiTi (PO ４ ) ３ LiGe(PO ４ ) ３ LiLaTiO ３ These are some examples.

[0043] The solid electrolyte can be one or more of those exemplified above. Among the solid electrolytes exemplified above, a sulfide-based solid electrolyte is more preferable because it has high lithium ion conductivity and also has the function of improving the moldability of the negative electrode mixture.

[0044] For example, carbon materials such as carbon black can be used as the conductive additive for the negative electrode 202.

[0045] The negative electrode mixture may or may not contain a binder. If a binder is included in the negative electrode mixture, fluororesins such as polyvinylidene fluoride (PVDF) or acrylic resins can be used as the binder.

[0046] When a current collector is used for the negative electrode 202, the current collector can be made of copper, nickel, stainless steel, or aluminum foil, perforated metal, mesh, expanded metal, foamed metal, carbon sheet, etc.

[0047] The negative electrode 202 can be manufactured by preparing a negative electrode mixture by mixing lithium titanium oxide particles (an active material), a solid electrolyte, and a conductive additive, for example, without using a solvent, and then molding this mixture into pellets or the like.

[0048] Alternatively, a negative electrode mixture may be prepared by mixing the above-mentioned negative electrode mixture with a solvent, and this mixture may be applied to a substrate such as a current collector or a solid electrolyte layer 203 that faces the negative electrode 202. After drying, a press treatment may be performed to form a molded body of the negative electrode mixture.

[0049] When selecting a solvent for a negative electrode mixture-containing composition, it is preferable to choose one that does not easily degrade the solid electrolyte. In particular, since sulfide-based and hydride-based solid electrolytes undergo chemical reactions with even trace amounts of water, it is preferable to use nonpolar aprotic solvents such as hydrocarbon solvents like hexane, heptane, octane, nonane, decane, decalin, toluene, and xylene. It is especially preferable to use an ultra-dehydrated solvent with a water content of 0.001% by mass (10 ppm) or less. In addition, fluorine-based solvents such as "Bartrell®" from Mitsui DuPont Fluorochemicals, "Zeolora®" from Nippon Zeon Corporation, and "Novec®" from Sumitomo 3M Corporation, as well as non-aqueous organic solvents such as dichloromethane and diethyl ether, can also be used.

[0050] The composition of the negative electrode mixture is preferably such that the negative electrode active material content is 50 to 80% by mass, the solid electrolyte content is preferably 20 to 50% by mass, and the conductive additive content is preferably 0.1 to 10% by mass. Furthermore, if a binder is included in the negative electrode mixture, its content is preferably 0.1 to 10% by mass. In addition, the thickness of the molded negative electrode mixture (or the thickness of the molded negative electrode mixture on one side of the current collector if the negative electrode mixture is present on both sides of the current collector) is preferably 50 μm or more from the viewpoint of increasing the battery capacity, preferably 2000 μm or less, and more preferably 1000 μm or less to reduce internal resistance.

[0051] The solid electrolyte in the solid electrolyte layer 203 can be one or more of the same types as those previously exemplified for the solid electrolyte of the negative electrode 202. However, to improve battery characteristics, it is desirable to include a sulfide-based solid electrolyte, and it is even more desirable to include a sulfide-based solid electrolyte in all of the positive electrode 201, negative electrode 202, and solid electrolyte layer 203. The solid electrolyte layer 203 may have a porous material such as a resin nonwoven fabric as a support.

[0052] The solid electrolyte layer 203 is a cylindrical molded body (layer) formed by pressure molding of a solid electrolyte by compression, rolling, or the like. The solid electrolyte layer is not limited to a cylindrical shape; it may also be a prismatic layer. Furthermore, the solid electrolyte layer may be formed by applying a composition for forming the solid electrolyte layer 203, prepared by dispersing a solid electrolyte in a solvent, onto a substrate, a positive electrode, or a negative electrode, drying it, and then performing pressure molding such as a press treatment as needed.

[0053] The solvent used in the composition for forming the solid electrolyte layer 203 should, like the solvent used in the negative electrode mixture-containing composition, be one that does not easily degrade the solid electrolyte. It is preferable to use the various solvents exemplified above as the solvent for the negative electrode mixture-containing composition, and it is particularly preferable to use an ultra-dehydrated solvent with a water content of 0.001% by mass (10 ppm) or less. The thickness of the solid electrolyte layer 203 is preferably 10 to 200 μm.

[0054] [Manufacturing of the Laminate 20] The laminate 20 is manufactured by attaching a heat-shrinkable tube 212, a positive electrode tab 206, and a negative electrode tab 207 to an electrode body 211 composed of the positive electrode 201, a solid electrolyte layer 203, and a negative electrode 202 described above. As shown in Figure 2, the all-solid-state secondary battery 1 of the first embodiment has 10 laminates 20 (20a, 20b, 20c, 20d, 20e, 20f, 20g, 20h, 20i, 20j). The number of laminates 20 in the all-solid-state secondary battery 1 is not limited to 10, and may be more or less than 10.

[0055] Figures 3A to 3D illustrate the manufacturing process of the laminate 20. Figure 3A is an external view showing the electrode body 211 and heat shrink tube 212 that constitute the laminate 20. The cylindrical electrode body 211 is inserted into the cylindrical heat shrink tube 212. At this time, polarity sheets 201a and 202a are attached to the electrode body 211. Polarity sheet 201a is attached to the side of the electrode body 211 where the positive electrode 201 is formed. Polarity sheet 202a is attached to the side of the electrode body 211 where the negative electrode 202 is formed.

[0056] The heat-shrinkable tube 212 is manufactured from a polymer such as polyethylene or various elastomers, and is non-conductive. When the heat-shrinkable tube 212 is heated with the electrode body 211 inserted inside, the heat-shrinkable tube 212 shrinks.

[0057] Figure 3B is an external perspective view of the electrode body 211 with the heat shrink tubing 212 attached. The sides and the periphery of the top and bottom surfaces of the electrode body 211 are covered with the shrunk heat shrink tubing 212. By attaching the heat shrink tubing 212, separation of the electrode body 211 and the polarity sheets 201a and 202a is suppressed. In addition, since the heat shrink tubing 212 is made of a non-conductive material, it is possible to insulate at least one of the positive electrode power supply plate 30 and the negative electrode power supply plate 40 from contacting the side surface of the electrode body 211 and causing a short circuit.

[0058] The heat shrink tubing 212 may be attached after the positive electrode tab 206 and negative electrode tab 207, described later, have been joined to the polarity sheets 201a and 202a, respectively.

[0059] Figure 3C is a perspective view of the laminate 20 (20a, 20b, 20c, 20d, 20e, 20f, 20g, 20h, 20i). Figure 3D is a perspective view of the laminate 20 (20j).

[0060] The electrode body 211 (see Figure 3B), to which the heat shrink tubing 212 is attached, has a positive electrode tab 206 and a negative electrode tab 207 joined to it, for example, by resistance welding. Specifically, the positive electrode tab 206 is joined to a polarity sheet 201a provided on the surface of the electrode body 211 where the positive electrode 201 is formed. The negative electrode tab 207 is joined to a polarity sheet 202a provided on the surface of the electrode body 211 where the negative electrode 202 is formed.

[0061] The positive electrode tab 206 is made of a metal material such as stainless steel. The negative electrode tab 207 is made of a metal material such as stainless steel.

[0062] The positive electrode tab 206, which is connected to the positive electrode 201, has a main portion 206a and a connecting portion 206b. The main portion 206a is formed in a plate shape that extends in a direction intersecting the first direction L1. The main portion 206a is joined to the polarity sheet 201a attached to the positive electrode 201, for example by resistance welding, and is electrically connected to the positive electrode 201. The connecting portion 206b is connected to one end of the main portion 206a and extends along the first direction L1, which is the direction intersecting the main portion 206a. The connecting portion 206b is joined to the positive electrode power supply plate 30, which will be described later, for example by resistance welding. As a result, the positive electrode 201 of the laminate 20 and the positive electrode power supply plate 30 are electrically connected.

[0063] The negative electrode tab 207, which is connected to the negative electrode 202, has a main portion 207a and a connecting portion 207b. The main portion 207a is formed in a plate shape that extends in a direction intersecting the first direction L1. The main portion 207a is joined to the polarity sheet 202a attached to the negative electrode 202, for example by resistance welding, and is electrically connected to the negative electrode 202.

[0064] The connecting portion 207b is connected to the end of the main portion 207a and extends along a first direction L1 which is a direction that intersects (specifically, is perpendicular to) the main portion 207a. The connecting portion 207b extends from the surface of the negative electrode 202 in a direction toward approaching the positive electrode 201 along the first direction L1.

[0065] As shown in Figures 3C and 3D, the negative electrode tab 207 is attached to the positive electrode tab 206 at a position where the connection portion 207b of the negative electrode tab 207 and the connection portion 206b of the positive electrode tab 206 are symmetrical with respect to the central axis of the cylindrical laminate 20 (i.e., the connection portions 206b and 207b face each other). The connection portion 207b is joined to the negative electrode power supply plate 40, which will be described later, for example by resistance welding. This electrically connects the negative electrode 202 of the laminate 20 to the negative electrode power supply plate 40.

[0066] [Manufacturing of Cell Assembly 21] Figure 4 is an exploded perspective view of the cell assembly 21. The cell assembly 21 consists of 10 laminated bodies 20 (20a, 20b, 20c, 20d, 20e, 20f, 20g, 20h, 20i, 20j), which are multiple cells, and 9 insulating plates 210 (210a, 210b, 210c, 210d, 210e, 210f, 210g, 210h, 210i), which are laminated together.

[0067] Multiple stacks 20 are arranged by stacking them along a first direction L1. Specifically, each stack 20 is arranged such that the negative electrode 202 is on the lower side and the positive electrode 201 is on the upper side. However, the arrangement is not limited to having the negative electrode 202 facing downwards; it may also be arranged with the positive electrode 201 facing downwards. Furthermore, the stacks 20 may be arranged in parallel, in series, or a combination of parallel and series. This makes it possible to arrange the stacks 20 according to the required voltage or current and the available space. The number of stacks 20 is not limited to 10; it may be more or less than 10. Also, in the following description, each stack 20 may be referred to as a cell.

[0068] Multiple stacked laminates 20 are held from below, the sides, and above by a holder 22. Each of the multiple stacked laminates 20 has a positive electrode tab 206 which is connected to a positive electrode power supply plate 30. Each of the multiple stacked laminates 20 has a negative electrode tab 207 which is connected to a negative electrode power supply plate 40. The cell assembly 21, which is composed of the multiple stacked laminates 20 held by the holder 22 and a portion of the positive electrode power supply plate 30 and a portion of the negative electrode power supply plate 40 connected to the stacked laminates 20, is covered with a heat shrink tubing 213.

[0069] The insulating plate 210 is a soft elastic material such as silicone rubber. The insulating plate 210 is placed between each laminate 20. Specifically, the insulating plate 210a is placed between the upper surface of laminate 20a and the lower surface of laminate 20b. The insulating plate 210b is placed between the upper surface of laminate 20b and the lower surface of laminate 20c. The insulating plate 210c is placed between the upper surface of laminate 20c and the lower surface of laminate 20d. The insulating plate 210d is placed between the upper surface of laminate 20d and the lower surface of laminate 20e. The insulating plate 210e is placed between the upper surface of laminate 20e and the lower surface of laminate 20f. The insulating plate 210f is placed between the upper surface of laminate 20f and the lower surface of laminate 20g. The insulating plate 210g is placed between the upper surface of laminate 20g and the lower surface of laminate 20h. The insulating plate 210h is placed between the upper surface of laminate 20h and the lower surface of laminate 20i. An insulating plate 210i is placed between the upper surface of the laminate 20i and the lower surface of the laminate 20j.

[0070] The insulating plate 210 is formed in a disc shape according to the cylindrical shape of each laminate 20. However, the insulating plate 210 is not limited to being formed in a disc shape, but can be formed in a shape according to the shape of the laminate 20. For example, if the laminate 20 is prism-shaped, the insulating plate 210 will be formed in a polygonal plate shape.

[0071] The placement of the insulating plate 210 allows the laminates 20a, 20b, 20c, 20d, 20e, 20f, 20g, 20h, 20i, and 20j to be arranged in an insulated state. The insulating plate 210 is not limited to being a soft elastic material. However, if the insulating plate 210 is a soft elastic material, it has the effect of cushioning impacts in the first direction L1 to the laminates 20 that are stacked along the first direction L1. Furthermore, if the insulating plate 210 is a soft elastic material, the joints of the positive electrode tab 206 and negative electrode tab 207 connected to the laminates 20 are covered by the soft elastic material, so the load stress applied to the joints is suppressed.

[0072] [Holder 22] The holder 22 holds a plurality of laminates 20 and insulating plates 210 arranged along the first direction L1. The holder 22 is made of a resin material that has insulating properties, flexibility, and water-non-absorbent properties, such as polypropylene, polyester, or elastomer-blended plastic resin. In particular, when the all-solid-state secondary battery 1 is required to have heat resistance to high temperatures (e.g., 150°C or higher), a thermoplastic material with rubber-like elasticity is used as the material for the holder 22.

[0073] As shown in Figure 4, the holder 22 has a first holding portion 23 and a second holding portion 24. The first holding portion 23 holds the bottom and sides of the stacked plurality of laminates 20. The second holding portion 24 holds the top of the uppermost laminate 20j of the stacked plurality of laminates 20.

[0074] The first holding portion 23 has a bottom holding portion 231 and two side holding portions 232. The number of side holding portions 232 is not limited to two; there may be more or fewer than two. The bottom holding portion 231 is a circular plate shape corresponding to the shape of the cylindrical laminate 20. If the laminate 20 is rectangular prism-shaped, the bottom holding portion 231 is formed as a polygonal plate.

[0075] The side retaining portion 232 extends along the first direction L1 and is connected to the bottom retaining portion 231 at its lower end. The two side retaining portions 232 are provided around the bottom retaining portion 231, for example, at 180-degree intervals. A hook-shaped bent portion 232a is formed above the side retaining portion 232.

[0076] Figure 5A is a perspective view of the first holding portion 23 of the holder 22 during molding. As shown in Figure 5A, each of the two side holding portions 232 extends radially outward from the circumference of the bottom holding portion 231. The side holding portions 232 are connected to the bottom holding portion 231 by a bent portion 232b. The side holding portions 232 are bent relative to the bottom holding portion 231 in the direction A1 shown in Figure 5A, with the bent portion 232b as the pivot point. As a result, the first holding portion 23 takes on the shape shown in Figure 4.

[0077] The laminate 20 is housed in the space enclosed by the bottom holding portion 231 and the side holding portion 232. When the laminate 20 is housed, as shown in Figure 4, the bent portion 232a of the side holding portion 232 is inclined radially outward. Therefore, when housing the laminate 20 in the first holding portion 23, the upper end of the side holding portion 232 does not get in the way, improving work efficiency.

[0078] As shown in Figure 4, a sheet 233, for example, made of silicone, is placed between the bottom holding portion 231 and the laminate 20a. The sheet 233 is provided to facilitate the rotation of the laminate 20 relative to the holder 22 when manufacturing the cell assembly 21. By rotating the laminate 20 on the sheet 233, the position adjustment work of aligning each positive electrode tab 206 and each negative electrode tab 207 of each laminate 20 housed in the holder 22 to the first direction L1 becomes easier. Note that the sheet 233 is not required.

[0079] When the laminate 20 is housed in the first holding portion 23, the upper part of the side holding portion 232 is bent in the direction A2 shown in Figure 4, with the lower end portion 232c of the bent portion 232a as the pivot point. As a result, the contact surface 232d of the bent portion 232a above the lower end portion 232c comes into contact with the upper surface of the uppermost laminate 20j. The upper tip portion 232e, which is formed above the upper end of the side holding portion 232a above the contact surface 232d, extends upward along the first direction L1. The upper tip portion 232e has a fitting portion that protrudes outward.

[0080] Figure 5B is an external perspective view of the second holding portion 24 of the holder 22. The second holding portion 24 has two semicircular portions 240 and 241 and a rectangular housing portion 242. The housing portion 242 is provided between the semicircular portions 240 and 241, connected to the semicircular portion 240 at one wall surface and connected to the semicircular portion 241 at the wall surface opposite to the one wall surface. The upper surface of the housing portion 242 is lower than the upper surface of the semicircular portions 240 and 241. That is, the housing portion 242 forms a recess relative to the semicircular portions 240 and 241.

[0081] The upper surface of the housing section 242 houses the connecting portion 206b of the positive electrode tab 206 provided on the uppermost laminated body 20j (see Figure 3D), which is bent in a direction intersecting the first direction L1. In addition, the housing section 242 houses the contact connecting portion 302 of the positive electrode power supply plate 30, which will be described later, above the housed connecting portion 206b.

[0082] Each of the semicircular portions 240 and 241 has a receiving opening 243. In other words, the second holding portion 24 has two receiving openings 243. The receiving opening 243 formed in the semicircular portion 240 and the receiving opening 243 formed in the semicircular portion 241 face each other with the center of the second holding portion 24 in between. That is, the two receiving openings 243 are formed at 180-degree intervals along the circumferential direction of the second holding portion 24.

[0083] The receiving opening 243 is a through hole that penetrates the semicircular portions 240 and 241 in the vertical direction. The circumferential length of the receiving opening 243 is approximately equal to the width of the side retaining portion 232 of the first retaining portion 23, and the radial length of the receiving opening 243 is approximately equal to the thickness of the side retaining portion 232.

[0084] When the second retaining portion 24 is positioned on top of the laminate 20j, the upper tip portion 232e of the side retaining portion 232 of the first retaining portion 23 is inserted into the receiving opening 243. When the upper tip portion 232e is inserted into the receiving opening 243, the fitting portion formed on the upper tip portion 232e engages with the upper surfaces of the semicircular portions 240 and 241, and the second retaining portion 24 is fixed to the first retaining portion 23.

[0085] [Positive electrode power supply plate 30] The positive electrode power supply plate 30 is a metal material such as stainless steel, aluminum, or nickel alloy that electrically connects the positive electrode 201 of the laminate 20 to the electrode terminals of the can lid portion 50, which will be described later. As shown in Figure 2, the positive electrode power supply plate 30 has a positive electrode tab connection portion 301, a contact connection portion 302, and a positive electrode expandable portion 60. As shown in Figure 4, the positive electrode tab connection portion 301 and the contact connection portion 302 are formed by bending a single plate-shaped member. The positive electrode tab connection portion 301 has a long side along the first direction L1. The positive electrode tab connection portion 301 is joined to the positive electrode tabs 206 attached to the laminates 20a, 20b, 20c, 20d, 20e, 20f, 20g, 20h, 20i, 20j by, for example, resistance welding.

[0086] The contact connection portion 302 is connected to the upper end of the positive electrode tab connection portion 301 and extends in a direction intersecting the first direction L1. The contact connection portion 302 is housed in a housing portion 242 formed on the upper surface of the second holding portion 24 of the holder 22. The lower surface of the contact connection portion 302 is joined to the positive electrode tab 206 of the laminate 20j housed in the housing portion 242 of the second holding portion 24, for example by resistance welding. The upper surface of the contact connection portion 302 is joined to the positive electrode expandable portion 60, for example by resistance welding, laser welding, brazing, etc. Details of the positive electrode expandable portion 60 will be described later.

[0087] [Negative electrode power supply plate 40] The negative electrode power supply plate 40 is a component that electrically connects the negative electrode 202 of the laminate 20 to the battery can 10. The negative electrode power supply plate 40 is made of a metal material such as stainless steel, aluminum, or nickel alloy. The negative electrode power supply plate 40 is composed of a negative electrode tab connection portion 401, a negative electrode expandable portion 402, and a connection portion 403. The negative electrode tab connection portion 401 extends along a first direction L1 and is joined to the negative electrode tabs 207 attached to each of the negative electrodes 202 of the multiple laminates 20 by means of resistance welding, for example.

[0088] As shown in Figure 4, the lower end of the negative electrode tab connection portion 401 in the first direction L1 is bent and joined to the negative electrode expandable portion 402 by, for example, resistance welding. The connection portion 403 and the negative electrode expandable portion 402 are formed by bending a single plate-shaped member. The connection portion 403 extends along the first direction L1 and is connected to the negative electrode expandable portion 402 at its lower end. The negative electrode expandable portion 402 will be described in detail later.

[0089] The upper end of the connection portion 403 protrudes above the upper end of the cell assembly 21. Two upper ends 404 and 405 are formed at the upper end of the connection portion 403. Each of these two upper ends 404 and 405 is joined to the inner circumferential surface of the side surface 102 of the battery can 10 by welding or the like. Alternatively, the connection portion 403 may not have upper ends 404 and 405 formed on it, and a single upper end may be formed instead.

[0090] [Heat shrink tubing 213] Figure 6 is an external perspective view illustrating the process of attaching the heat shrink tubing 213 to the cell assembly 21. Figures 7A and 7B are external perspective views showing the cell assembly 21 covered with the heat shrink tubing 213. Figure 7A shows the cell assembly 21 viewed from above, and Figure 7B shows the cell assembly 21 viewed from below.

[0091] The sides of the cell assembly 21 are covered with heat-shrinkable tubing 213. The heat-shrinkable tubing 213 is a non-conductive material made from a polymer such as polyethylene or various elastomers.

[0092] Multiple laminates 20 constituting the cell assembly 21, a holder 22, a positive electrode tab connection portion 301 which is part of the positive electrode power supply plate 30, and a negative electrode tab connection portion 401 which is part of the negative electrode power supply plate 40 are inserted into a cylindrical heat shrink tube 213. When the heat shrink tube 213 is heated in this state, it shrinks. As a result, as shown in the external perspective views of Figures 7A and 7B, the multiple laminates 20, the holder 22, the positive electrode tab connection portion 301, and the negative electrode tab connection portion 401 are covered by the heat shrink tube 213. However, the second holding portion 24 of the holder 22, which is located on the uppermost surface of the cell assembly 21, is not covered by the heat shrink tube 213. Also, the vicinity of the upper end of the positive electrode tab connection portion 301 and the contact connection portion 302, and the negative electrode expansion portion 402 and connection portion 403 are not covered by the heat shrink tube 213.

[0093] By covering the sides of the cell assembly 21 with heat-shrinkable tubing 213, the multiple laminates 20 constituting the cell assembly 21 can be fixed in place. This prevents the laminates 20 from separating or falling off. Furthermore, it prevents the detachment of the positive electrode tab connection portion 301 of the positive electrode power supply plate 30, which is joined to the positive electrode tab 206, or the detachment of the negative electrode tab connection portion 401 of the negative electrode power supply plate 40, which is joined to the negative electrode tab 207. In addition, when the cell assembly 21 is housed in the battery can 10, the heat-shrinkable tubing 213 prevents the positive electrode tab connection portion 301 from directly contacting the battery can 10. As a result, the occurrence of short circuits due to contact between the positive electrode power supply plate 30 and the battery can 10 is suppressed.

[0094] As shown in Figure 7A, a positive electrode insulating seal 215 is attached, for example by adhesive, near the upper end of the positive electrode tab connection portion 301 of the positive electrode power supply plate 30, that is, near the position where it is connected to the contact connection portion 302. By attaching the positive electrode insulating seal 215, it is suppressed that a short circuit will occur when the positive electrode power supply plate 30 of the cell assembly 21 housed in the battery can 10 comes into contact with the battery can 10. However, if it is possible to cover the area near the upper end of the positive electrode tab connection portion 301 of the positive electrode power supply plate 30 with the heat shrink tubing 213, the positive electrode insulating seal 215 does not need to be attached.

[0095] [Attachment of cushioning material 70 and housing in battery can 10] Figures 8A and 8B are external perspective views of the cell assembly 21 with the cushioning material 70 attached. Figure 8A shows the cell assembly 21 viewed from above, and Figure 8B shows the cell assembly 21 viewed from below.

[0096] The cushioning material 70 is manufactured from a soft material with a rubber hardness of 20 degrees or less (i.e., a penetration degree of 60 degrees or less), such as a silicone rubber-based material. The cushioning material 70 is manufactured by various methods, such as press molding, injection molding, foam molding, or dip molding. As shown in Figure 4, the cushioning material 70 is cylindrical with openings at one end (upper side) and the other end (lower side) in the first direction L1. The cell assembly 21 is housed inside the cylindrical cushioning material 70.

[0097] In other words, as shown in Figures 8A and 8B, the cell assembly 21 is wrapped by the inner circumferential surface 707 of the cushioning material 70. More specifically, the sides of the cell assembly 21 are wrapped by the cushioning material 70, while the top surface (second holding portion 24 and contact connection portion 302) and the bottom surface (bottom holding portion 231 and negative electrode expansion portion 402) are not wrapped by the cushioning material 70. That is, the inside of the cushioning material 70 is in contact with the sides of the cell assembly 21. Also, the positive electrode tab connection portion 301, which is part of the positive electrode power supply plate 30, extends along the first direction L1 on the side surface of the cell assembly 21. Therefore, when the cell assembly 21 is wrapped in the cushioning material 70, the positive electrode tab connection portion 301 is positioned between the cell assembly 21 and the cushioning material 70. Also, the negative electrode tab connection portion 401, which is part of the negative electrode power supply plate 40, extends along the first direction L1 on the side surface of the cell assembly 21. Therefore, when the cell assembly 21 is wrapped in the cushioning material 70, the negative electrode tab connection portion 401 is positioned between the cell assembly 21 and the cushioning material 70.

[0098] The outer diameter of the cushioning material 70 is smaller than the inner diameter of the battery can 10. Therefore, the cell assembly 21 is housed inside the battery can 10 while wrapped in the cushioning material 70. Specifically, the outside of the cushioning material 70 housed in the battery can 10 is in contact with the inside of the battery can 10.

[0099] A notch 702 is formed on the side surface 701 of the cushioning material 70, along the first direction L1. When the cushioning material 70 is attached to the cell assembly 21, the connecting portion 403 that constitutes the negative electrode power supply plate 40 is housed in the notch 702 (see Figures 8A and 8B).

[0100] In the first direction L1, the length of the cushioning material 70 is longer than the length of the cell assembly 21 and equal to or approximately equal to the length of the battery can 10. That is, the upper end surface 703 of the cushioning material 70 is located above the second holding portion 24 of the holder 22, and the lower end surface 704 of the cushioning material 70 is located below the bottom holding portion 231 of the first holding portion 23 (see Figure 2).

[0101] On the inner circumferential surface 707 of the cushioning material 70 (see Figure 4), a first stepped portion 705 is formed on the upper side in the first direction L1, and a second stepped portion 706 is formed on the lower side in the first direction L1. The inner diameters of the first stepped portion 705 and the second stepped portion 706 are smaller than the diameter of the cell assembly 21. Therefore, when the cushioning material 70 is attached to the cell assembly 21, the lower end surface of the first stepped portion 705 contacts the upper surface of the second holding portion 24, and the upper end surface of the second stepped portion 706 contacts the bottom holding portion 231 of the first holding portion 23 (see Figure 2). In other words, the cell assembly 21 with the cushioning material 70 attached is held from above by the first stepped portion 705 and from below by the second stepped portion 706 in the first direction L1.

[0102] Figure 9 is a perspective view of the battery can 10 in which the cell assembly 21 is housed. As shown in Figure 9, the cell assembly 21 is wrapped in cushioning material 70 and housed inside the battery can 10.

[0103] As described above, in the first direction L1, the length of the cushioning material 70 is equal to or approximately equal to the length of the battery can 10. Therefore, as shown in Figure 2, the upper end surface 703 of the cushioning material 70 is in contact with the can lid portion 50, which will be described later, and the lower end surface 704 of the cushioning material 70 is in contact with the bottom surface 101 of the battery can 10. As a result, the cell assembly 21 is held in place by the cushioning material 70 within the all-solid-state secondary battery 1.

[0104] When the all-solid-state secondary battery 1 is dropped, the impact force is calculated by multiplying the acceleration of the all-solid-state secondary battery 1 at the time of the fall by the mass of the cell assembly 21. This impact force may cause the cell assembly 21 to be displaced (moved) within the battery can 10. However, the cushioning material 70, which is a soft material interposed between the battery can 10 and the cell assembly 21, is compressed by the impact force, mitigating the impact force transmitted to the cell assembly 21. As a result, the impact force transmitted to the laminate 20 can be reduced.

[0105] The structure of the cushioning material 70 is not limited to that described above. Figure 10 is an external perspective view of another example of the cushioning material 70. As shown in Figure 10, a plurality of holes 710 are formed in the side surface 701 of the cushioning material 70. The holes 710 are through holes that penetrate the inner circumferential surface 707 and the outer circumferential surface of the side surface 701. In Figure 10, it is shown that the holes 710 are elongated holes with a longer side along the first direction L1.

[0106] As described above, when an impact is transmitted from the outside, such as when the all-solid-state secondary battery 1 is dropped, the cushioning material 70 is compressed by that impact. Generally, the greater the amount of compression of the cushioning material 70 due to the impact, the greater the cushioning effect on the cell assembly 21. Furthermore, if the cushioning material 70 is a soft elastic material with low material hardness, the amount of compression will be even greater. The holes 710 formed on the side surface 701 function as relief holes for shape changes due to compression when an impact is transmitted and the cushioning material 70 is compressed. Therefore, the cushioning effect of the cushioning material 70 can be improved. Note that the shape of the holes 710 is not limited to the shape shown in Figure 10, and can be set to a suitable shape depending on the material, manufacturing method, and shape of the cushioning material 70.

[0107] As shown in Figures 8A and 8B, the upper ends 404 and 405 of the connecting portion 403 constituting the negative electrode power supply plate 40 are housed in a notch 702 formed in the side surface 701 of the cushioning material 70. That is, the connecting portion 403 is not housed in the area surrounded by the inner circumferential surface 707 of the cushioning material 70. For this reason, the upper ends 404 and 405 of the connecting portion 403 can be joined to the inner circumferential surface of the side surface 102 of the battery can 10 by welding or the like. By joining the upper ends 404 and 405 to the battery can 10, the negative electrode power supply plate 40 electrically connects the negative electrode 202 and the battery can 10.

[0108] When the cell assembly 21 is housed in the battery can 10, the negative electrode extension portion 402 of the negative electrode power supply plate 40 is positioned between the bottom surface 101 of the battery can 10 and the bottom surface holding portion 231 of the first holding portion 23 of the holder 22. Note that the configuration is not limited to the negative electrode power supply plate 40 being joined to the battery can 10. The positive electrode power supply plate 30 may also be joined to the battery can 10. In this case, the negative electrode power supply plate 40 can be configured to contact the can lid portion 50, which will be described later.

[0109] [Can Lid 50] Figure 11A is an upper perspective view of the can lid 50, and Figure 11B is a lower perspective view of the can lid 50. The can lid 50 has a main body 51, electrode terminals 52, an insulating part 53, and an insulating sheet 54.

[0110] The can lid portion 50 is attached to the upper end, which is one end of the battery can 10, thereby sealing the opening of the battery can 10 (see Figure 2). After the can lid portion 50 is press-fitted onto the upper end of the battery can 10, it is joined to the battery can 10 by, for example, laser welding, thereby sealing the opening of the battery can 10.

[0111] The main body portion 51 is made of, for example, a metal material and is disc-shaped according to the shape of the opening of the battery can 10. As shown in Figure 11B, an insulating sheet 54 is provided on the lower surface of the main body portion 51. The lower surface of the main body portion 51 is the surface that faces the bottom surface 101 of the battery can 10 when the can lid portion 50 is attached to the battery can 10. A chamfered edge 510 is formed on the outer periphery of the lower surface of the main body portion 51. The chamfered edge 510 functions as a guide when fitting the can lid portion 50 into the opening of the battery can 10. An opening 511 is formed in the center of the can lid portion 50. The opening 511 is a through hole that penetrates the main body portion 51 in the vertical direction.

[0112] The insulating portion 53 is made of a non-conductive material, such as a glass sintered material or a ceramic sintered material. The insulating portion 53 is provided in the opening 511 of the main body portion 51. An opening 531 is formed in the center of the insulating portion 53. The opening 531 is a through hole that penetrates the insulating portion 53 in the vertical direction.

[0113] The electrode terminal 52 is made of a conductive material and is positioned in the opening 531. The electrode terminal 52 is cylindrical and is formed by a first projection 521 and a second projection 522. The first projection 521 protrudes upward from the upper surface of the main body 51. The first projection 521 contacts electrical contacts, etc., of a device to which the all-solid-state secondary battery 1 is mounted.

[0114] The second protrusion 522 protrudes downward from the lower surface of the main body 51. That is, when the can lid 50 is attached to the battery can 10, the second protrusion 522 protrudes toward the bottom surface 101 of the battery can 10. The amount of protrusion of the first protrusion 521 relative to the main body 51 is greater than the amount of protrusion of the second protrusion 522 relative to the main body 51.

[0115] The second protrusion 522 protrudes downward by 0.1 mm relative to the insulating sheet 54 provided on the lower surface of the main body 51. The insulating sheet 54 is made of, for example, a resin material and has a thickness of about 0.1 mm. Therefore, the amount of downward protrusion of the second protrusion 522 is about 0.2 mm. In other words, the amount of protrusion of the second protrusion 522 is greater than the thickness of the insulating sheet 54.

[0116] The second protrusion 522 is electrically connected to the positive electrode power supply plate 30 described above. Specifically, the second protrusion 522 is joined to the positive electrode extension portion 60 by, for example, resistance welding, laser welding, brazing, etc. When the positive electrode power supply plate 30 is joined to the battery can 10, the negative electrode power supply plate 40 is electrically connected to the second protrusion 522.

[0117] Furthermore, the main body 51, the electrode terminals 52, and the insulating part 53 are integrally molded. Specifically, if the insulating part 53 is made of glass sintered material, the glass powder that is the material of the insulating part 53 is molded by press molding or the like. At this time, the insulating part 53 is formed in a cylindrical shape that can be inserted into the opening 511 of the main body 51 and to which the electrode terminals 52 can be attached. The main body 51, the electrode terminals 52, and the insulating part 53 are then integrally molded by sintering the glass material of the insulating part 53 in an electric furnace or the like using the glass hermetic method.

[0118] [Positive electrode expandable portion 60] The positive electrode expandable portion 60 of the positive electrode power supply plate 30 is a plate-shaped member made of a conductive material, such as stainless steel, aluminum, or nickel alloy. Note that an electric wire may be used as the positive electrode expandable portion 60. As shown in Figure 2, the plate-shaped member has a folded shape formed by being bent (folded back) alternately in opposite directions at multiple bending points (three bending points in Figure 2). One end of the positive electrode expandable portion 60 is joined to the second protrusion 522 of the electrode terminal 52 provided on the can lid portion 50 by, for example, resistance welding, laser welding, brazing, etc. The other end of the positive electrode expandable portion 60 is joined to the contact connection portion 302 of the positive electrode power supply plate 30 by, for example, resistance welding, laser welding, brazing, etc. Note that when the positive electrode power supply plate 30 is joined to the battery can 10, the other end of the positive electrode expandable portion 60 is joined to the negative electrode power supply plate 40.

[0119] Figure 12A is a lower perspective view of the can lid 50 with the positive electrode extension portion 60 joined to the second protrusion 522. As shown in Figure 12A, the width D1 of one end of the positive electrode extension portion 60 is greater than or equal to the diameter D2 of the second protrusion 522. Therefore, compared to the case where the width D1 is less than the diameter D2, the contact area between the joined positive electrode extension portion 60 and the second protrusion 522 can be increased. As a result, the resistance value at the joint between the positive electrode extension portion 60 and the electrode terminal 52 can be reduced.

[0120] Figure 12B is a partial cross-sectional view of the area near the upper end of the all-solid-state secondary battery 1, as shown in the cross-sectional view of Figure 2. The positive electrode expandable portion 60 is positioned between the cell assembly 21 and the can lid portion 50. More specifically, the positive electrode expandable portion 60 is positioned between the second holding portion 24 and the can lid portion 50. The positive electrode expandable portion 60 is folded back at bending points P1, P2, and P3. By folding back at bending points P1, P2, and P3, the positive electrode expandable portion 60 forms a first flat portion 601, a second flat portion 602, a third flat portion 603, a fourth flat portion 604, a first curved portion 605, a second curved portion 606, and a third curved portion 607.

[0121] The first flat section 601, the second flat section 602, the third flat section 603, and the fourth flat section 604 each extend in a direction intersecting the first direction L1 and are housed inside the battery can 10 and can lid 50 in an overlapping state with a gap in the first direction L1. The first curved section 605 is the part connecting the first flat section 601 and the second flat section 602, and is formed by bending the positive electrode expandable section 60 at the bending point P1. The second curved section 606 is the part connecting the second flat section 602 and the third flat section 603, and is formed by bending the positive electrode expandable section 60 at the bending point P2. The third curved section 607 is the part connecting the third flat section 603 and the fourth flat section 604, and is formed by bending the positive electrode expandable section 60 at the bending point P3.

[0122] The positive electrode expandable portion 60 expands and contracts at the first curved portion 605, the second curved portion 606, and the third curved portion 607 in response to movement in the first direction L1, by being bent at the bending points P1, P2, and P3 as described above. The three first curved portions 605, the second curved portion 606, and the third curved portion 607 provided on the positive electrode expandable portion 60 are formed so as not to come into contact with the inside of the battery can 10 and the negative electrode power supply plate 40, which will be described later. Specifically, the straight-line distance R1 from the central axis AX of the battery can 10 to the first curved portion 605 or the third curved portion 607, and the straight-line distance R2 from the central axis AX to the second curved portion 606 are between 1 / 2 and 2 / 3 of the radius R3 of the battery can 10. In other words, the straight-line distance from the bending points P1, P2, and P3 to the central axis AX is greater than 1 / 2 of the radius R3 and less than 2 / 3 of the radius R3. Here, the straight-line distance refers to the distance along the direction that intersects (orthogonal or nearly orthogonal to) the central axis AX. The angles formed between two adjacent flat sections (for example, the first flat section 601 and the second flat section 602, the second flat section 602 and the third flat section 603, and the third flat section 603 and the fourth flat section 604) are called the interior angles θ1, θ2, and θ3 at the bending points P1, P2, and P3. If the angles of the interior angles θ1, θ2, and θ3 are too small, it becomes impossible to secure space for the positive electrode expandable section 60 to expand and contract with respect to movement along the first direction L1. Also, if the interior angles θ1, θ2, and θ3 are too large, the mountable volume of the cell assembly 21 within the battery can 10 decreases, resulting in a smaller battery capacity. For this reason, the angles of the interior angles θ1, θ2, and θ3 at the bending points P1, P2, and P3 are set to 30 degrees or less. As a result, when an impact is applied and the cell assembly 21 moves in the first direction L1, the impact force applied to the laminate 20 is mitigated by the bending of the positive electrode expansion / contraction portion 60, and the motion strain in the radial direction perpendicular to the first direction L1 is also absorbed.

[0123] A portion of the first flat portion 601 (for example, one end) is one end of the positive electrode extension portion 60 and is joined to the contact connection portion 302. A portion of the fourth flat portion 604 (for example, one end) is the other end of the positive electrode extension portion 60 and is joined to the electrode terminal 52. As described above, since the second protrusion 522 of the electrode terminal 52 protrudes below the insulating sheet 54, contact between the positive electrode extension portion 60 and the main body portion 51 and short-circuiting is suppressed.

[0124] As described above, the joining of the positive electrode expandable portion 60 and the electrode terminal 52, and the joining of the positive electrode expandable portion 60 and the contact connection portion 302 are performed by, for example, resistance welding, laser welding, brazing, etc. Therefore, even when a high impact force is applied to the all-solid-state secondary battery 1, friction between the contact surfaces and an increase in contact resistance, as would occur in the case of contact bonding, is suppressed. Furthermore, when a high impact force is applied to the all-solid-state secondary battery 1, momentary disconnection chatter, in which the connection points between the positive electrode expandable portion 60 and the electrode terminal 52, and the connection points between the contact connection portion 302 (i.e., the laminate 20) and the positive electrode expandable portion 60 are momentarily separated, is suppressed. In other words, electrical conductivity between the electrode terminal 52 and the positive electrode 201 via the positive electrode expandable portion 60 is interrupted, and a decrease in the output voltage of the all-solid-state secondary battery 1 is suppressed.

[0125] Furthermore, the positive electrode expandable portion 60 is not limited to being bent at three bending points P1, P2, and P3; the number of bending points can be two or more. Figure 12C schematically shows the positive electrode expandable portion 60 when two bending points P1 and P2 are provided. The positive electrode expandable portion 60 shown in Figure 12C expands and contracts at the first curved portion 605 and the second curved portion 606 in response to movement in the first direction L1 by being bent at the two bending points P1 and P2. In this case as well, the first curved portion 605 formed at bending point P1 and the second curved portion 606 formed at bending point P2 are formed so as not to come into contact with the inside of the battery can 10 and the negative electrode power supply plate 40 which will be described later. That is, the straight-line distance R1 from the central axis AX of the battery can 10 to the first curved portion 605 and the straight-line distance R2 from the central axis AX to the second curved portion 606 are between 1 / 2 and 2 / 3 of the radius R3 of the battery can 10. In other words, the straight-line distances R1 and R2 from the bending points P1 and P2 to the central axis AX are greater than half of the radius R3 and less than two-thirds of the radius R3. Furthermore, even if four or more bending points are formed in the positive electrode expansion / contraction section 60, none of the curved sections will come into contact with the inside of the battery can 10 or the negative electrode power supply plate 40. That is, the straight-line distance between all the bending points (curved sections) and the central axis AX of the battery can 10 is between half and two-thirds of the radius R3 of the battery can 10. Also, as shown in Figure 12C, the angles of the interior angles θ1 and θ2 of the bending points P1 and P2 are 30 degrees or less, as described above. Even if four or more bending points are provided, the angle of each interior angle is 30 degrees or less. As a result, as described above, when an impact is applied and the cell assembly 21 moves in the first direction L1, the impact force applied to the laminate 20 is mitigated by the bending of the positive electrode expansion / contraction portion 60, and the motion strain in the radial direction perpendicular to the first direction L1 is also absorbed.

[0126] [Negative electrode expandable portion 402] Figure 13 is a partial cross-sectional view showing an enlarged view of the area near the lower end of the all-solid-state secondary battery 1 from the cross-sectional view shown in Figure 2. The negative electrode expandable portion 402 of the negative electrode power supply plate 40 is made of a conductive material, such as a metal material such as stainless steel, aluminum, or nickel alloy. As shown in Figure 13, the negative electrode expandable portion 402 is positioned between the cell assembly 21 and the bottom surface 101 of the battery can 10. More specifically, the negative electrode expandable portion 402 is positioned between the bottom surface holding portion 231 and the bottom surface 101.

[0127] The negative electrode expandable portion 402 has a folded shape formed by a plate-shaped member being alternately bent (folded back) in opposite directions at multiple bending points (two bending points in Figure 13). Specifically, the negative electrode expandable portion 402 is folded back at bending points P11 and P12. The negative electrode expandable portion 402 is formed by folding back at bending points P11 and P12, resulting in a first flat portion 410, a second flat portion 411, a third flat portion 412, a first curved portion 413, and a second curved portion 414.

[0128] The first flat section 410, the second flat section 411, and the third flat section 412 each extend in a direction intersecting the first direction L1 and are housed inside the battery can 10 in an overlapping state with a gap in the first direction L1. The first curved section 413 is the part that connects the first flat section 410 and the second flat section 411 at the bending point P11. The second curved section 414 is the part that connects the second flat section 411 and the third flat section 412 at the bending point P12.

[0129] One end of the first flat section 410 is one end of the negative electrode expandable section 402 and is connected to the lower end of the connecting section 403. One end of the third flat section 412 is the other end of the negative electrode expandable section 402 and is joined to the negative electrode tab connecting section 401. The negative electrode expandable section 402 and the negative electrode tab connecting section 401 are joined, for example, by resistance welding.

[0130] The negative electrode expandable portion 402 expands and contracts at the first curved portion 413 and the second curved portion 414 in response to movement in the first direction L1, by being bent at the bending points P11 and P12 as described above. The two first curved portions 413 and the second curved portion 414 provided on the negative electrode expandable portion 402 are formed so as not to come into contact with the inside of the battery can 10. Specifically, the straight-line distance R4 from the central axis AX of the battery can 10 to the first curved portion 413 and the straight-line distance R5 from the central axis AX to the second curved portion 414 are between 1 / 2 and 2 / 3 of the radius R3 of the battery can 10. In other words, the straight-line distance from the bending points P11 and P12 to the central axis AX is greater than 1 / 2 of the radius R3 and less than 2 / 3 of the radius R3. Furthermore, since the first flat portion 410 follows the inner surface of the bottom surface 101 of the battery can 10, the distance from the central axis AX of the battery can 10 to the connection portion 403 is equal to or approximately equal to the radius R3 of the battery can 10. Also, the angles formed by two adjacent flat portions (for example, the first flat portion 410 and the second flat portion 411, and the second flat portion 411 and the third flat portion 412) are called the interior angles θ11 and θ12 at the bending points P11 and P12. If the angles of the interior angles θ11 and θ12 are too small, it will not be possible to secure space for the negative electrode expansion / contraction portion 402 to expand and contract with respect to movement along the first direction L1. Also, if the interior angles θ11 and θ12 are too large, the mountable volume of the cell assembly 21 inside the battery can 10 will decrease, and the battery capacity will decrease. For this reason, the angles of the interior angles θ11 and θ12 at the bending points P11 and P12 are set to 30 degrees or less. As a result, when an impact is applied and the cell assembly 21 moves in the first direction L1, the impact force applied to the laminate 20 is mitigated by the bending of the negative electrode expansion / contraction portion 402, and the motion strain in the radial direction perpendicular to the first direction L1 is also absorbed.

[0131] Since the negative electrode expandable portion 402 and the negative electrode tab connection portion 401 are joined by resistance welding or the like, even when a high impact force is applied to the all-solid-state secondary battery 1, friction between the contact surfaces and an increase in contact resistance, as would occur in the case of contact joining, are suppressed. Furthermore, when a high impact force is applied to the all-solid-state secondary battery 1, momentary disconnection chattering at the connection point between the negative electrode expandable portion 402 and the negative electrode tab connection portion 401 is suppressed. In other words, electrical conductivity between the negative electrode power supply plate 40 and the negative electrode 202 is interrupted, and a decrease in the output voltage of the all-solid-state secondary battery 1 is suppressed.

[0132] Furthermore, the negative electrode expandable portion 402 is not limited to being bent at two bending points P11 and P12; the number of bending points may be more or less than two. Figure 13B schematically shows the negative electrode expandable portion 402 when one bending point P11 is provided. The negative electrode expandable portion 402 shown in Figure 13B expands and contracts at the first curved portion 413 in response to movement in the first direction L1 by being bent at one bending point P11. In this case as well, the first curved portion 413 formed at the bending point P11 is formed so as not to come into contact with the inside of the battery can 10. That is, the straight-line distance R4 from the central axis AX of the battery can 10 to the first curved portion 413 is between 1 / 2 and 2 / 3 of the radius R3 of the battery can 10. In other words, the straight-line distance R4 from the bending point P11 to the central axis AX is greater than 1 / 2 of the radius R3 and less than 2 / 3 of the radius R3. Furthermore, even if three or more bending points are formed in the negative electrode expandable portion 402, none of the curved portions will come into contact with the inside of the battery can 10. That is, the straight-line distance between all the bending points (curved portions) and the central axis AX of the battery can 10 is between 1 / 2 and 2 / 3 of the radius R3 of the battery can 10. Also, as shown in Figure 13B, the angle of the interior angle θ11 of the bending point P11 is 30 degrees or less, as described above. Even if four or more bending points are provided, the angle of each interior angle is 30 degrees or less. As a result, as described above, when an impact is applied and the cell assembly 21 moves in the first direction L1, the impact force applied to the laminate 20 by bending the negative electrode expandable portion 402 is mitigated, and the motion strain in the radial direction perpendicular to the first direction L1 is also absorbed. In addition, in the negative electrode power supply plate 40, the negative electrode tab connection portion 401 is a separate component from the negative electrode expandable portion 402 and the connection portion 403. However, the negative electrode tab connection portion 401, the negative electrode extension portion 402, and the connection portion 403 of the negative electrode power supply plate 40 may be formed from a single component.

[0133] As described above, the positive electrode expandable portion 60 is positioned between the cell assembly 21 and the can lid portion 50, and the negative electrode expandable portion 402 is positioned between the cell assembly 21 and the bottom surface 101. Since the positive electrode expandable portion 60 and the negative electrode expandable portion 402 have a folded shape, they are elastic along the first direction L1. In other words, the cell assembly 21 is connected to the elastic positive electrode expandable portion 60 and the negative electrode expandable portion 402 at the top and bottom.

[0134] When the all-solid-state secondary battery 1 is dropped, as described above, the impact force is obtained by multiplying the acceleration of the all-solid-state secondary battery 1 at the time of the fall by the mass of the cell assembly 21. Due to this impact force, the cell assembly 21 may be displaced (moved) along the first direction L1 within the battery can 10. That is, the distance between the cell assembly 21 and the can lid 50, and the distance between the cell assembly 21 and the bottom surface 101 may increase or decrease. However, because the positive electrode expandable portion 60 and the negative electrode expandable portion 402, which have a folded shape, expand and contract along the first direction L1, it is possible to suppress the stress (force) acting on the joints of the positive electrode power supply plate 30 and the negative electrode power supply plate 40 even when the cell assembly 21 moves along the first direction L1. As a result, the load stress (force) applied to the joint between the positive electrode expandable portion 60 and the electrode terminal 52, the joint between the positive electrode expandable portion 60 and the contact connection portion 302, the joint between the negative electrode expandable portion 402 and the negative electrode tab connection portion 401, and the joint between the negative electrode power supply plate 40 and the battery can 10 can be reduced. Therefore, the risk of the joint coming undone and the electrical connection being interrupted due to the load stress (force) applied to the aforementioned joints is suppressed.

[0135] [Attachment of the can lid 50 (sealing the battery can 10)] The can lid 50 is attached to the battery can 10, which contains the cell assembly 21 wrapped in cushioning material 70. Figures 14A and 14B illustrate the process of attaching the can lid 50 to the battery can 10, with Figure 14A being an external perspective view and Figure 14B being a side view. First, as shown in Figure 14A, the positive electrode extension portion 60 is joined to the electrode terminals 52 of the can lid 50 and the contact connection portion 302 housed inside the battery can 10. Specifically, the first flat portion 601 of the positive electrode extension portion 60 is joined to the contact connection portion 302 housed in the housing portion 242 of the second holding portion 24 of the holder 22. Also, the fourth flat portion 604 is joined to the electrode terminals 52.

[0136] Subsequently, as shown in Figure 14B, with the lower surface of the can lid 50 facing the upper surface of the second holding portion 24, the can lid 50 is moved downward along the first direction L1 and press-fitted into the battery can 10. After that, the peripheral edge of the can lid 50 and the upper end of the battery can 10 are joined along the joint, for example by laser welding. As a result, the battery can 10 is sealed by the can lid 50. As a result, an all-solid-state secondary battery 1 having the appearance shown in Figure 1 is manufactured.

[0137] At this time, the can lid 50 is attached to the battery can 10 with the thickness direction of the insulating portion 53 of the can lid 50 aligned with the first direction L1 of the battery can 10. The cell assembly 21 is housed in the battery can 10 with the thickness direction of the laminate 20 aligned with the first direction L1. Therefore, when the can lid 50 is attached to the battery can 10, the thickness direction of the laminate 20 and the thickness direction of the insulating portion 53 are aligned with the first direction L1. In other words, the laminate 20 and the insulating portion 53 are aligned with the first direction L1 in the direction in which they have low resistance to temperature changes.

[0138] Furthermore, the sealing by the can lid 50 is performed in a vacuum environment. In this case, the pressure difference should be 1 atmosphere (0.1 MPa). Because the sealing is performed in a vacuum environment, the inside of the battery can 10 becomes negative pressure under atmospheric pressure. As a result, the bottom surface 101 of the battery can 10 is indented inward. By measuring this indentation with, for example, a laser displacement meter, it is possible to check whether or not the battery can 10 is properly sealed.

[0139] [Method for Manufacturing All-Solid-State Secondary Battery 1] The method for manufacturing the all-solid-state secondary battery 1 will be described with reference to the flowchart shown in Figure 15. In step S1, a laminate 20 is manufactured (first step). In this case, an electrode body 211 is formed by pressure molding, in which a positive electrode 201, a negative electrode 202, and a solid electrolyte layer 203 are laminated.

[0140] Furthermore, a positive electrode tab 206 is manufactured from a metal material such as stainless steel, and a negative electrode tab 207 is manufactured from a metal material such as stainless steel. The positive electrode tab 206 is then joined to a polarity sheet 201a provided on the positive electrode 201 of the electrode body 211. The negative electrode tab 207 is then joined to a polarity sheet 202a provided on the negative electrode 202 of the electrode body 211.

[0141] In step S2, the cell assembly 21 is manufactured (second step). In this case, multiple laminates 20, each manufactured by joining a positive electrode tab 206 and a negative electrode tab 207 to an electrode body 211, are stacked. Then, the positive electrode power supply plate 30 and the negative electrode power supply plate 40 are attached to manufacture the cell assembly 21.

[0142] Depending on the manufacturing line, the process of joining the positive electrode tab 206 and the negative electrode tab 207 to the electrode body 211, which is performed in step S1 above, may be performed in step S2. In this case, in step S2, the positive electrode tab 206 and the negative electrode tab 207 are joined to the electrode body 211, and after the laminate 20 is manufactured, the cell assembly 21 is manufactured. Furthermore, the positive electrode 201, the negative electrode 202 and the solid electrolyte layer 203 of the electrode body 211 are laminated along the first direction L1, which is the direction of thickness, and in the cell assembly 21, multiple laminates 20 are laminated along the first direction L1.

[0143] In step S3, the cell assembly 21 is wrapped in cushioning material 70, and the cell assembly 21 with the positive electrode expandable portion 60 and the negative electrode expandable portion 402 attached is housed inside the battery can 10 (third step). At this time, the cell assembly 21 is housed inside the battery can 10 along the first direction L1.

[0144] Furthermore, the cushioning material 70 is an elastic material made of a soft material and has a high surface friction coefficient. Therefore, it is preferable that the cell assembly 21 be housed in the battery can 10 with the sides 701 of the cushioning material 70 wrapped with a slip sheet 71 (see Figures 4, 8A, 8B, etc.) that has low surface friction. The slip sheet 71 is an insulating material with a thickness of about 0.1 mm, such as polyester, carbonate, or non-combustible paper. Because the sides 701 are wrapped with the slip sheet 71, the surface friction coefficient of the part of the cushioning material 70 that comes into contact with the inner surface of the battery can 10 is reduced, improving the workability when storing it in the battery can 10. However, the slip sheet 71 is not required to be used.

[0145] The upper ends 404 and 405 of the negative electrode power supply plate 40 are then joined to the battery can 10 by resistance welding or the like. As a result, the negative electrode 202 and the battery can 10 are electrically connected by the negative electrode power supply plate 40.

[0146] In step S4, the can lid portion 50 is manufactured (fourth step). In this case, the can lid portion 50 is manufactured by integrally molding an insulating portion 53 formed by compressing an insulating material, a main body portion 51, and electrode terminals 52. Note that the fourth step is not limited to being performed after the third step, but may be performed before the first step, before the second step, or before the third step.

[0147] In step S5, the can lid 50 is attached to the opening on one side of the battery can 10 in the first direction L1, sealing the opening of the battery can 10 (fifth step). In step S6, the sealed battery can 10 is subjected to a chemical treatment, and then the performance test of the all-solid-state secondary battery 1 is performed (sixth step). During the chemical treatment, the all-solid-state secondary battery 1, sealed by the can lid 50, is heated at a predetermined high temperature for a predetermined time. Note that if the electrode body 211 contains a sulfide-based solid electrolyte, hydrogen sulfide gas may be generated from the laminate 20 when the chemical treatment is performed. For this reason, the chemical treatment may be performed after the battery can 10 is sealed by the can lid 50. The all-solid-state secondary battery 1 is manufactured through the above steps. According to the first embodiment described above, at least one of the following effects can be obtained.

[0148] (1) The all-solid-state secondary battery 1 has a cylindrical cushioning material 70 that encloses a plurality of stacked laminates 20. A positive electrode power supply plate 30 connected to the positive electrode 201 of the laminate 20 is provided with a positive electrode expandable portion 60 which is positioned between the cell assembly 21 and the can lid portion 50 and connected to the electrode terminals 52. A negative electrode power supply plate 40 connected to the negative electrode 202 of the laminate 20 is provided with a negative electrode expandable portion 402 which is positioned between the cell assembly 21 and the bottom surface 101 of the battery can 10 and connected to the battery can 10.

[0149] The laminate 20, manufactured by pressure molding powder material, is fragile and therefore difficult to enlarge. Furthermore, enlarging the laminate 20 results in the disadvantage of longer charging time. In this embodiment, in order to avoid enlarging the laminate 20 and to obtain the desired voltage and capacity, multiple laminates 20 are stacked and electrically connected. Even if an impact force is applied to the all-solid-state secondary battery 1 due to factors such as dropping, the laminate 20 is not damaged by the impact force. Therefore, the all-solid-state secondary battery 1 is required to have significantly higher resistance to impact forces (for example, 500 [G] or more) compared to conventional batteries.

[0150] In the all-solid-state secondary battery 1 of this embodiment, even when an impact force is applied, the cushioning material 70 interposed between the battery can 10 and the cell assembly 21 mitigates the impact force transmitted to the cell assembly 21. That is, the impact force transmitted to the laminate 20 is reduced, and damage to the laminate 20 is suppressed.

[0151] Furthermore, the positive electrode expandable portion 60 and the negative electrode expandable portion 402 suppress the stress (force) acting on the joints of the positive electrode power supply plate 30 and the negative electrode power supply plate 40, even when the cell assembly 21 moves along the first direction L1 due to the impact force applied to the all-solid-state secondary battery 1. In other words, when the distance between the cell assembly 21 and the can lid portion 50, and the distance between the cell assembly 21 and the bottom surface 101 increase or decrease, the load stress (force) acting on the joints of the positive electrode power supply plate 30, the negative electrode power supply plate 40, and the positive electrode tab 206 and negative electrode tab 207 attached to the laminate 20 is suppressed, and the joints coming apart and electrical conduction being interrupted is suppressed. Since the load stress (force) acting on the joints of the positive electrode tab 206 and negative electrode tab 207 attached to the laminate 20 is suppressed, it can be said that the load stress (force) acting on the laminate 20 is suppressed. This suppresses the application of large forces to the laminate 20. In this way, the impact force is mitigated by the cushioning material 70, and the force acting on the laminate 20 due to movement is suppressed by the positive electrode expandable portion 60 and the negative electrode expandable portion 402. Therefore, the all-solid-state secondary battery 1 can withstand high impact forces exceeding 500 [G] as described above.

[0152] (2) The cushioning material 70 is an elastic member with a rubber hardness of 20 degrees or less. That is, the cushioning material 70 is made of a soft material. This makes it possible to increase the amount of compression that the cushioning material 70 is compressed by the impact force acting on the all-solid-state secondary battery 1, and thus increase the cushioning effect on the cell assembly 21.

[0153] (3) In the first direction L1 intersecting with the can lid 50, the cushioning material 70 contacts the can lid 50 at one end surface, the upper end surface 703, and contacts the bottom surface 101 of the battery can 10 at the other end surface, the lower end surface 704. As a result, movement of the cell assembly 21 together with the cushioning material 70 within the battery can 10 is suppressed, and the impact force transmitted to the cell assembly 21 (i.e., the laminate 20) is reduced.

[0154] (4) The positive electrode expandable portion 60 has a folded shape formed by folding at two or more bending points P1 to P3. The negative electrode expandable portion 402 has a folded shape formed by folding at one or more bending points P11 to P12. As a result, the cell assembly 21 is connected to the elastic positive electrode expandable portion 60 and the negative electrode expandable portion 402 at the top and bottom. As a result, with a simple structure, a positive electrode expandable portion 60 and a negative electrode expandable portion 402 that expand and contract along the first direction L1 when an impact force is applied to the all-solid-state secondary battery 1 can be obtained.

[0155] <Second Embodiment> The all-solid-state secondary battery of the second embodiment will be described below. Hereinafter, the same reference numerals will be used for components similar to those of the all-solid-state secondary battery 1 of the first embodiment, and the differences from the first embodiment will be described primarily. Components that are not specifically described are the same as those of the first embodiment.

[0156] Figure 16 is a cross-sectional view of the all-solid-state secondary battery 1 of the second embodiment. In the all-solid-state secondary battery 1 of the second embodiment, the laminate 80 arranged along the first direction L1 is different from the laminate 20 of the first embodiment. The laminate 80 has a housing portion 81 that houses the electrode body 211, and a positive electrode tab 84 and a negative electrode tab 85 that are joined to the housing portion 81.

[0157] In the second embodiment as well, ten laminates 80 (80a, 80b, 80c, 80d, 80e, 80f, 80g, 80h, 80i, 80j) are stacked along the first direction L1. However, the number of laminates 80 is not limited to 10; it may be more or less than 10.

[0158] Figures 17A, 17B, and 17C are external perspective views of the laminate 80. Figure 17A shows the appearance of the uppermost laminate 80j, Figure 17B shows the appearances of 80b, 80c, 80d, 80e, 80f, 80g, 80h, and 80i, and Figure 17C shows the appearance of the bottommost laminate 80a. The housing section 81 has a disc-shaped flattened form. Because the housing section 81 has the above shape, the laminate 80 of the second embodiment is a so-called coin battery or button battery. If the electrode body 211 is polygonal prism-shaped, the housing section 81 can also be polygonal flattened.

[0159] Figure 18 is a cross-sectional view of the laminate 80. The housing section 81 has a positive electrode casing 82 and a negative electrode casing 83. The positive electrode casing 82 is made of a metal material such as stainless steel. The positive electrode casing 82 has a bottomed cylindrical shape and is open on the lower side in the first direction L1. Specifically, the positive electrode casing 82 has a flat section 821 and a side wall section 822. The flat section 821 is circular in shape according to the shape of the electrode body 211. The side wall section 822 is formed along the outer circumference of the flat section 821 and extends in a direction intersecting the flat section 821 (first direction L1).

[0160] The negative electrode casing 83 is made of a metal material such as stainless steel. The negative electrode casing 83 has a bottomed cylindrical shape and is open on the upper side in the first direction L1. Specifically, the negative electrode casing 83 has a flat portion 831 and a side wall portion 832. The flat portion 831 is circular in shape according to the shape of the electrode body 211. The side wall portion 832 is formed along the outer circumference of the flat portion 831 and extends in a direction intersecting the flat portion 831.

[0161] The positive electrode casing 82 and the negative electrode casing 83 are fixed to each other after the electrode body 211 is housed in the internal space. Specifically, the side wall portion 822 of the positive electrode casing 82 and the side wall portion 832 of the negative electrode casing 83 are fixed to each other by crimping, for example, via a resin material such as a gasket. More specifically, with the openings of the positive electrode casing 82 and the negative electrode casing 83 facing each other, the side wall portion 832 of the negative electrode casing 83 is inserted inside the side wall portion 822 of the positive electrode casing 82. Then, with a resin material interposed between the side wall portions 822 and 832, the side wall portions 822 and 832 are fixed to each other by crimping.

[0162] As shown in Figure 18, the positive electrode 201 of the electrode body 211 housed in the housing 81 is electrically connected to the flat portion 821 of the positive electrode casing 82. In this case, the positive electrode 201 and the flat portion 821 may be in direct contact, or they may be connected via a conductive member. The negative electrode 202 of the electrode body 211 housed in the housing 81 is electrically connected to the flat portion 831 of the negative electrode casing 83. In this case, the negative electrode 202 and the flat portion 831 may be in direct contact, or they may be connected via a conductive member.

[0163] The positive electrode tab 84 is made of a metal material such as stainless steel. The positive electrode tab 84 is joined to the flat portion 821 of the positive electrode casing 82 of the housing portion 81. As shown in Figures 17A to 17C, the positive electrode tab 84 has a main portion 841 and a connecting portion 842. The main portion 841 is plate-shaped and extends in a direction intersecting the first direction L1. The main portion 841 extends along the edge of the flat portion 821. The main portion 841 is joined to the flat portion 821, which is electrically connected to the positive electrode 201, by means of resistance welding or the like, and is electrically connected to the positive electrode 201.

[0164] The connecting portion 842 is connected to one end of the main portion 841. The connecting portion 842 extends radially outward from the side wall portion 822 of the positive electrode casing 82 and along a first direction L1 that intersects with the main portion 841. The connecting portion 842 is provided with a connecting mechanism 842a. The connecting mechanism 842a has, for example, a fitting portion and an opening. When the laminates 80 are stacked, the opening of the connecting mechanism 842a of one laminate 80 (for example, laminate 80b) engages with the fitting portion of the connecting mechanism 842a of another laminate 80 (for example, laminate 80c). Note that, as shown in Figure 17A, the connecting mechanism 842a of the uppermost laminate 80j does not necessarily have to have an opening. Furthermore, the shape of the connecting mechanism 842a is not limited to the one having a fitting portion and an opening as described above, and any configuration that allows the positive electrode tabs 84 to be connected to each other can be applied.

[0165] The negative electrode tab 85 is made of a metal material such as stainless steel. The negative electrode tab 85 is joined to the flat portion 831 of the negative electrode casing 83 of the housing portion 81. The negative electrode tab 85 has a main portion 851 and a connecting portion 852. The main portion 851 is plate-shaped and extends in a direction intersecting the first direction L1. The main portion 851 extends along the edge of the flat portion 831. The main portion 851 is joined to the flat portion 831, which is electrically connected to the negative electrode 202, by means of resistance welding or the like, and is electrically connected to the negative electrode 202.

[0166] The connecting portion 852 is connected to one end of the main portion 851. The connecting portion 852 extends radially outward from the side wall portion 822 of the positive electrode casing 82 and along a first direction L1 that intersects with the main portion 851. The connecting portion 852 is provided with a connecting mechanism 852a. The connecting mechanism 852a has, for example, a fitting portion and an opening. When the laminates 80 are stacked, the opening of the connecting mechanism 852a of one laminate 80 (for example, laminate 80b) engages with the fitting portion of the connecting mechanism 852a of another laminate 80 (for example, laminate 80c). Note that, as shown in Figure 17C, the connecting mechanism 852a of the bottommost laminate 80a does not necessarily have an opening. Furthermore, the shape of the connecting mechanism 852a is not limited to the one having a fitting portion and an opening as described above, and any configuration that allows the negative electrode tabs 85 to be connected to each other can be applied.

[0167] The laminated body 80 described above is subjected to a chemical conversion treatment before the positive electrode tab 84 and the negative electrode tab 85 are joined to it. In other words, the positive electrode tab 84 and the negative electrode tab 85 are attached to the housing section 81 in which the electrode body 211, which has undergone the chemical conversion treatment and passed the performance inspection, is housed. Note that the chemical conversion treatment may also be performed after the positive electrode tab 84 and the negative electrode tab 85 have been joined.

[0168] Figure 19 is an exploded perspective view of the cell assembly 21. The cell assembly 21 consists of 10 laminated bodies 80 (80a, 80b, 80c, 80d, 80e, 80f, 80g, 80h, 80i, 80j), which are multiple cells, and 10 insulating plates 210 (210a, 210b, 210c, 210d, 210e, 210f, 210g, 210h, 210i, 210j), which are stacked together. The laminated bodies 80 stacked along the first direction L1 are connected to each other by the connecting mechanisms 842a and 852a described above.

[0169] In the second embodiment, the insulating plate 210 is annular. The insulating plates 210 (210a, 210b, 210c, 210d, 210e, 210f, 210g, 210h, 210i, 210j) are arranged between each laminate 80, as in the first embodiment. However, the insulating plate 210j is arranged between the lower surface of the laminate 80a and the bottom holding portion 231 of the holder 22. That is, the insulating plate 210j is arranged in place of the sheet 233 in the first embodiment.

[0170] In the laminate 80, the electrode body 211 is housed within the housing section 81. The planar sections 821 and 831 of the housing section 81 may develop bulges that rise in the first direction L1. These bulges are caused by linear expansion of the housing section 81, expansion of gases or the electrode body 211 within the housing section 81 in a high-temperature environment, or gases generated from the electrode body 211.

[0171] The bulging may be most pronounced in the central part of the flat sections 821 and 831. To suppress the effects of deformation of the housing section 81 due to the bulging, the insulating plate 210 is formed in an annular shape. Furthermore, the main portion 841 of the positive electrode tab 84 and the main portion 851 of the negative electrode tab 85 extend along the edges of the flat sections 821 and 831, also to suppress the effects of deformation of the housing section 81 due to the bulging.

[0172] The stacked laminates 80 and the insulating plate 210 are housed and held in the holder 22 in the same manner as in the first embodiment. Subsequently, the positive electrode tab connection portion 301 of the positive electrode power supply plate 30 is joined to the positive electrode tab 84 of each laminate 80, and the negative electrode tab connection portion 401 of the negative electrode power supply plate 40 is joined to the negative electrode tab 85 of each laminate 80.

[0173] Furthermore, since the positive electrode tabs 84 are connected by the connecting mechanism 842a, the positive electrodes 201 of the multiple laminates 80 are electrically connected. For this reason, the positive electrode tab connection portion 301 of the positive electrode power supply plate 30 may be joined only to the positive electrode tab 84 of the uppermost laminate 80j. Alternatively, the positive electrode power supply plate 30 may not have a positive electrode tab connection portion 301, and the contact connection portion 302 may be joined to the positive electrode tab 84 of the uppermost laminate 80j. Alternatively, the positive electrode power supply plate 30 may have only a positive electrode expandable portion 60, and the positive electrode expandable portion 60 may be joined to the positive electrode tab 84 of the uppermost laminate 80j.

[0174] Furthermore, since the negative electrode tabs 85 are connected by the connecting mechanism 852a, the negative electrodes 202 of the multiple laminates 80 are electrically connected. For this reason, the negative electrode tab connection portion 401 of the negative electrode power supply plate 40 may be joined only to the negative electrode tab 85 of the bottommost laminate 80a. Alternatively, the negative electrode power supply plate 40 may not have a negative electrode tab connection portion 401, and the negative electrode expandable portion 402 may be joined to the negative electrode tab 85 of the bottommost laminate 80a.

[0175] The all-solid-state secondary battery 1 of the second embodiment is manufactured by the same process as in the first embodiment. That is, the side surface of the cell assembly 21 is covered with heat-shrinkable tubing 213 (see Figures 7A and 7B), and the same cushioning material 70 as in the first embodiment is attached (see Figures 8A and 8B). In this embodiment as well, the cushioning material 70 having the holes 710 shown in Figure 10 may be used. The cell assembly 21 with the cushioning material 70 attached is housed in the battery can 10 after the positive electrode expandable portion 60 and the negative electrode expandable portion 402 are joined together (see Figure 9).

[0176] In the second embodiment, as shown in Figure 16, the cell assembly 21 is wrapped in a cushioning material 70 similar to that in the first embodiment. More specifically, the cell assembly 21 is held by the cushioning material 70 from above and below by the first stepped portion 705 and the second stepped portion 706. The upper end surface 703 of the cushioning material 70 is in contact with the can lid portion 50, and the lower end surface 704 is in contact with the bottom surface 101 of the battery can 10. Therefore, when the all-solid-state secondary battery 1 is dropped and an impact force is applied, the cushioning material 70, which is a soft material interposed between the battery can 10 and the cell assembly 21, is compressed, and the impact force transmitted to the cell assembly 21 is mitigated. As a result, in the second embodiment as well, the impact force transmitted to the laminate 80 is reduced.

[0177] Once the cell assembly 21 is housed in the battery can 10, the upper ends 404 and 405 of the connecting portion 403 constituting the negative electrode power supply plate 40 are joined to the battery can 10. That is, the negative electrode 202 and the battery can 10 are electrically connected by the negative electrode power supply plate 40. Then, the positive electrode extension portion 60 and the electrode terminals 52 of the can lid portion 50 are joined and assembled to the top of the can lid portion 50 and the battery can 10 (see Figures 14A and 14B). After that, the can lid portion 50 and the battery can 10 are joined together, for example by laser welding, and the battery can 10 is sealed.

[0178] In the second embodiment as well, the positive electrode expandable portion 60 is positioned between the cell assembly 21 and the can lid 50, and the negative electrode expandable portion 402 is positioned between the cell assembly 21 and the bottom surface 101 (see Figure 16). Also, similar to the first embodiment, the positive electrode expandable portion 60 and the negative electrode expandable portion 402 have a folded shape and are therefore elastic along the first direction L1. When the all-solid-state secondary battery 1 is dropped, the impact force causes the cell assembly 21 to be displaced (moved) along the first direction L1 within the battery can 10, causing the folded positive electrode expandable portion 60 and the negative electrode expandable portion 402 to expand and contract along the first direction L1.

[0179] As the positive electrode expandable portion 60 and the negative electrode expandable portion 402 expand and contract, even when the cell assembly 21 moves along the first direction L1 due to the impact force applied to the all-solid-state secondary battery 1, the stress (force) acting on the joints of the positive electrode power supply plate 30 and the negative electrode power supply plate 40 is suppressed. In other words, when the distance between the cell assembly 21 and the can lid portion 50, and the distance between the cell assembly 21 and the bottom surface 101 increase or decrease, the load stress (force) acting on the joints of the positive electrode power supply plate 30, the negative electrode power supply plate 40, and the positive electrode tab 84 and negative electrode tab 85 attached to the laminate 80 is suppressed, and the joints coming apart and electrical conduction being interrupted is suppressed.

[0180] Since the load stress (force) acting on the joint between the positive electrode tab 84 and the negative electrode tab 85 attached to the laminate 80 is suppressed, it can be said that the load stress (force) acting on the laminate 80 is suppressed. As a result, the large force acting on the laminate 80 is suppressed. In this way, the impact force is mitigated by the cushioning material 70, and the force acting on the laminate 80 due to movement is suppressed by the positive electrode expandable portion 60 and the negative electrode expandable portion 402, so the all-solid-state secondary battery 1 can withstand high impact forces exceeding 500 [G] as described above.

[0181] A method for manufacturing the all-solid-state secondary battery 1 of the second embodiment will be described with reference to the flowchart shown in Figure 20. In step S11, a laminate 80 is manufactured (first step). In this case, for example, an electrode body 211 in which a positive electrode 201, a negative electrode 202, and a solid electrolyte layer 203 are laminated is formed by pressure molding. The electrode body 211 is housed in a housing section 81 which is composed of a positive electrode casing 82 and a negative electrode casing 83.

[0182] In step S12, the laminate 80 in which the electrode body 211 is housed in the housing section 81 is subjected to a chemical conversion treatment, after which a performance test is performed (second step). During the chemical conversion treatment, the laminate 80 is heated at a predetermined high temperature for a predetermined time. If the electrode body 211 contains a sulfide-based solid electrolyte, hydrogen sulfide gas may be generated from the electrode body 211 when the chemical conversion treatment is performed. For this reason, the chemical conversion treatment may be performed after the electrode body 211 is housed in the housing section 81, which is composed of a positive electrode outer casing 82 and a negative electrode outer casing 83.

[0183] In step S13, a cell assembly 21 is manufactured using the laminate 80 that has passed the performance inspection after chemical conversion treatment (third step). In this case, a positive electrode tab 84 made from a metal material such as stainless steel and a negative electrode tab 85 made from a metal material such as stainless steel are joined to the housing section 81. Specifically, the positive electrode tab 84 is joined to the flat portion 821 of the positive electrode casing can 82 which constitutes the housing section 81 in which the electrode body 211 is housed. The negative electrode tab 85 is also joined to the flat portion 831 of the negative electrode casing can 83 which constitutes the housing section 81. Multiple laminates 80 manufactured by joining the positive electrode tab 84 and the negative electrode tab 85 are stacked. Then, the positive electrode power supply plate 30 and the negative electrode power supply plate 40 are attached to manufacture the cell assembly 21. Note that the chemical conversion treatment may be performed after the positive electrode tab 84 and the negative electrode tab 85 have been joined.

[0184] Furthermore, the positive electrode 201, negative electrode 202, and solid electrolyte layer 203 of the electrode body 211 are stacked along the first direction L1, which is the direction of thickness, and in the cell assembly 21, multiple stacks 80 are stacked along the first direction L1.

[0185] In step S14, the cell assembly 21 is wrapped in cushioning material 70, and the cell assembly 21 with the positive electrode expandable portion 60 and the negative electrode expandable portion 402 attached is housed in the battery can 10 (fourth step). At this time, the cell assembly 21 is housed in the battery can 10 along the first direction L1. When the cell assembly 21 is housed in the battery can 10, the sides of the cushioning material 70 may or may not be wrapped with the sliding sheet 71.

[0186] The upper ends 404 and 405 of the negative electrode power supply plate 40 are then joined to the battery can 10 by resistance welding or the like. As a result, the negative electrode 202 and the battery can 10 are electrically connected by the negative electrode power supply plate 40.

[0187] In step S15, the can lid portion 50 is manufactured (fifth step). The can lid portion 50 is manufactured by the same manufacturing method as in the first embodiment. Note that the fifth step is not limited to being performed after the fourth step, but may be performed before the first step, before the second step, before the third step, or before the fourth step. In step S16, the can lid portion 50 is attached to the opening on one side of the battery can 10 in the first direction L1, and the opening of the battery can 10 is sealed (sixth step). Through these steps, the all-solid-state secondary battery 1 is manufactured.

[0188] According to the second embodiment described above, in addition to the effects (1) to (4) obtained by the first embodiment, the following effects can be obtained.

[0189] (5) The laminate 80 has a housing section 81 that houses the positive electrode 201, the negative electrode 202, and the solid electrolyte layer 203. Therefore, cell assemblies 21 can be manufactured using laminates 80 that have undergone chemical treatment and have function as a battery, and that have passed performance inspections. In other words, it is prevented from manufacturing a defective all-solid-state secondary battery 1 that does not have the desired performance by using a cell assembly 21 that includes a defective laminate 80. Consequently, the wasteful consumption of various parts, materials, etc. used in the manufacture of the all-solid-state secondary battery 1 is suppressed, and productivity can be improved.

[0190] Furthermore, the positive electrode tab 84 and the negative electrode tab 85 can be joined to the housing section 81. This prevents damage to the electrode body 211 caused by excessive force during joining of the positive electrode tab 84 and the negative electrode tab 85.

[0191] <Third Embodiment> The all-solid-state secondary battery of the third embodiment will now be described. Hereinafter, the same reference numerals will be used for components similar to those of the all-solid-state secondary battery 1 of the first or second embodiment, and the differences from the first or second embodiment will be mainly described. Components that are not specifically described are the same as those of the first or second embodiment.

[0192] Figure 21 is an external perspective view of the all-solid-state secondary battery 1 of the third embodiment. Figure 22 is a cross-sectional view of the all-solid-state secondary battery 1 along the line B-B in Figure 21. The all-solid-state secondary battery 1 of the third embodiment differs from the first or second embodiment in that one stacked body 20 is arranged therein.

[0193] The laminate 20 of the third embodiment is the same as that of the first embodiment. A cushioning material 70 is attached to the laminate 20, as in the first and second embodiments. That is, the laminate 20 is wrapped by the inner circumferential surface 707 of the cushioning material 70. In this state, the laminate 20 is housed inside the battery can 10.

[0194] In the third embodiment, as shown in Figure 22, the length of the cushioning material 70 in the first direction L1 is longer than the length of the laminate 20. A first stepped portion 705 is formed at the upper end of the inner circumferential surface 707, and a second stepped portion 706 is formed at the lower end. Therefore, the laminate 20 housed inside the cushioning material 70 is held from above in the first direction L1 by the first stepped portion 705 and held from below in the first direction L1 by the second stepped portion 706.

[0195] In the third embodiment as well, in the first direction L1, the length of the cushioning material 70 is equal to or approximately equal to the length of the battery can 10. Therefore, as shown in Figure 22, the upper end surface 703 of the cushioning material 70 is in contact with the can lid 50, and the lower end surface 704 of the cushioning material 70 is in contact with the bottom surface 101 of the battery can 10. As a result, similar to the first and second embodiments, when the all-solid-state secondary battery 1 is dropped and an impact force is applied, the cushioning material 70, which is a soft material interposed between the battery can 10 and the laminate 20, is compressed, and the impact force transmitted to the laminate 20 is mitigated.

[0196] The positive electrode 201 of the laminate 20 is connected to the positive electrode power supply plate 30 by, for example, resistance welding. The positive electrode power supply plate 30 of the third embodiment does not have a positive electrode tab connection portion 301 and a contact connection portion 302, but has a positive electrode expandable portion 60. That is, the positive electrode expandable portion 60 is connected to the positive electrode 201 by being joined to the polarity sheet 201a. The positive electrode expandable portion 60 has the same folded shape as in the first and second embodiments.

[0197] Furthermore, the positive electrode power supply plate 30 may have a contact connection portion 302, and the contact connection portion 302 may be joined to the polarity sheet 201a. In this case, the positive electrode expandable portion 60 only needs to be joined to the contact connection portion 302.

[0198] The negative electrode 202 of the laminate 20 is connected to the negative electrode power supply plate 40 by, for example, resistance welding. The negative electrode power supply plate 40 of the third embodiment does not have a negative electrode tab connection portion 401, but has a negative electrode expandable portion 402 and a connection portion 403. That is, the negative electrode expandable portion 402 is connected to the negative electrode 202 by being joined to the polarity sheet 202a. The negative electrode expandable portion 402 has the same folded shape as in the first and second embodiments. Upper ends 404 and 405 are formed on the connection portion 403.

[0199] Once the positive electrode power supply plate 30 and the negative electrode power supply plate 40 are joined together and the laminated body 20, encased in cushioning material 70, is housed in the battery can 10, the all-solid-state secondary battery 1 of the third embodiment is manufactured by the same process as in the first and second embodiments. Specifically, the upper ends 404 and 405 of the connection portion 403 constituting the negative electrode power supply plate 40 are joined to the battery can 10. In other words, the negative electrode 202 and the battery can 10 are electrically connected by the negative electrode power supply plate 40. After the positive electrode extension portion 60 and the electrode terminals 52 of the can lid portion 50 are joined, the can lid portion 50 and the battery can 10 are joined together, for example by laser welding, and the battery can 10 is sealed.

[0200] In the third embodiment, the positive electrode expandable portion 60 is positioned between the laminate 20 and the can lid 50, and the negative electrode expandable portion 402 is positioned between the laminate 20 and the bottom surface 101 (see Figure 22). Also, similar to the first and second embodiments, the positive electrode expandable portion 60 and the negative electrode expandable portion 402 have a folded shape and are therefore elastic along the first direction L1. When the all-solid-state secondary battery 1 is dropped, the impact force causes the laminate 20 to be displaced (moved) along the first direction L1 within the battery can 10, causing the folded positive electrode expandable portion 60 and the negative electrode expandable portion 402 to expand and contract along the first direction L1.

[0201] As the positive electrode expandable portion 60 and the negative electrode expandable portion 402 expand and contract, even if the cell assembly 21 moves along the first direction L1 due to the impact force applied to the all-solid-state secondary battery 1, the stress (force) acting on the joints of the positive electrode power supply plate 30 and the negative electrode power supply plate 40 is suppressed. In other words, when the distance between the laminate 20 and the can lid portion 50, and the distance between the laminate 20 and the bottom surface 101 increases or decreases, the load stress (force) acting on the joints between the positive electrode power supply plate 30 and the negative electrode power supply plate 40 and the laminate 20 is suppressed, preventing the joints from coming apart and interrupting electrical conduction. Since the load stress (force) acting on the joints of the positive electrode power supply plate 30 and the negative electrode power supply plate 40 attached to the laminate 20 is suppressed, it can be said that the load stress (force) acting on the laminate 20 is suppressed. As a result, large forces acting on the laminate 20 are suppressed. In this way, the impact force is mitigated by the cushioning material 70, and the positive electrode expandable portion 60 and the negative electrode expandable portion 402 suppress the force acting on the laminate 20 due to movement. As a result, the all-solid-state secondary battery 1 can withstand high impact forces exceeding 500 [G] as described above.

[0202] A third embodiment of the method for manufacturing an all-solid-state secondary battery 1 will be described with reference to the flowchart shown in Figure 23. In step S21, a laminate 20 is manufactured (first step). In this case, for example, an electrode body 211 in which a positive electrode 201, a negative electrode 202, and a solid electrolyte layer 203 are laminated is formed by pressure molding.

[0203] In step S22, the positive electrode extension portion 60 of the positive electrode power supply plate 30 and the negative electrode extension portion 402 of the negative electrode power supply plate 40 are attached to the laminate 20. The laminate 20 is then wrapped in cushioning material 70 and housed inside the battery can 10 (second step). When the laminate 20 is housed inside the battery can 10, the sides of the cushioning material 70 may or may not be wrapped in a sliding sheet 71. The upper ends 404 and 405 of the negative electrode power supply plate 40 are then joined to the battery can 10 by resistance welding or the like. As a result, the negative electrode 202 and the battery can 10 are electrically connected by the negative electrode power supply plate 40.

[0204] In step S23, the can lid portion 50 is manufactured (third step). The can lid portion 50 is manufactured by the same manufacturing method as in the first embodiment. Note that the third step is not limited to being performed after the second step, but may be performed before the first step or before the second step. In step S24, the can lid portion 50 is attached to one side of the opening of the battery can 10 in the first direction L1, and the opening of the battery can 10 is sealed.

[0205] In step S25, the sealed battery case 10 is subjected to a chemical treatment, and then a performance test is conducted (fifth step). During the chemical treatment, the battery case 10 is heated at a predetermined high temperature for a predetermined time. If the electrode body 211 contains a sulfide-based solid electrolyte, hydrogen sulfide gas may be generated from the electrode body 211 when the chemical treatment is performed. For this reason, the chemical treatment may be performed after the battery case 10 is sealed. Through the above steps, an all-solid-state secondary battery 1 is manufactured.

[0206] According to the third embodiment described above, the same effects and benefits (1) to (4) obtained by the first or second embodiment can be obtained. In particular, since the all-solid-state secondary battery 1 of the third embodiment has a single stacked body 80, it can meet the small power demands of devices such as wristwatches, game consoles, and air pressure sensors in tire pressure monitoring systems. The air pressure sensor in a tire pressure monitoring system is a sensor that measures the air pressure of a tire installed on a vehicle such as an automobile, and is fixed to the tire wheel. Therefore, a high impact force acts on the air pressure sensor. The all-solid-state secondary battery 1 of this embodiment, like the first and second embodiments, has exceptional resistance to high impacts, and can therefore be used in devices to which high impact forces are applied, such as air pressure sensors.

[0207] Although embodiments of this disclosure have been specifically described above, the invention is not limited to the embodiments described above and can be modified in various ways without departing from the gist of the invention. Each embodiment can be modified by adding, deleting, or replacing components, except for essential components. Unless otherwise specified, each component may be singular or plural.

[0208] The can lid portion 50 is not limited to having a main body portion 51 made of a conductive material. For example, the can lid portion 50 may be integrally molded with electrode terminals 52 and an insulating portion 53. In this case, the outer diameter of the insulating portion 53 is equal to or approximately equal to the inner diameter of the upper end of the battery can 10. The can lid portion 50 is then attached to the battery can 10 by fixing the outer edge of the insulating portion 53 to the upper end of the battery can 10 by crimping or the like.

[0209] In the technology according to this embodiment, the impact resistance of the laminate can be improved by housing the laminate inside the battery can via a cushioning material, a positive electrode expandable plate, and a negative electrode expandable portion. The present invention, which provides such technology, can contribute to "Goal 9 of the United Nations' Sustainable Development Goals (SDGs): Build resilient infrastructure, promote inclusive and sustainable industrialization and foster innovation."

[0210] 1 All-solid-state secondary battery, 10 Battery can, 20, 20a, 20b, 20c, 20d, 20e, 20f, 20g, 20h, 20i, 20j, 80, 80a, 80b, 80c, 80d, 80e, 80f, 80g, 80h, 80i, 80j Laminate, 21 Cell assembly, 22 Holder, 23 First holding part, 24 Second holding part, 30 Positive electrode power supply plate, 40 Negative electrode power supply plate, 50 Can lid, 51 Main body, 52 Electrode terminals, 60 Positive electrode expandable part, 70 Cushioning material, 81 Housing part, 82 Positive electrode outer can, 83 Negative electrode outer can, 101 Bottom surface, 201 Positive electrode, 202 Negative electrode, 203 Solid electrolyte layer, 301 Positive electrode tab connection part, 302 Contact connection part, 401 Negative electrode tab connection part, 402 Negative electrode expandable part, 403 Connection part, 410 First flat part, 411 Second flat part, 412 Third flat part, 413 First curved part, 414 Second curved part, 601 First flat part, 602 Second flat part, 603 Third flat part, 604 Fourth flat part, 605 First curved part, 606 Second curved part, 607 Third curved part, 701 Side surface, 703 Upper end surface, 704 Lower end surface, 707 Inner circumferential surface, 710 Hole

Claims

1. A laminate having a positive electrode, a negative electrode, and a solid electrolyte layer interposed between the positive electrode and the negative electrode; a buffer material enclosing a cell assembly to which a plurality of the laminates are stacked, a positive electrode power supply plate connected to the power supply tabs of the positive electrodes of the plurality of laminates, and a negative electrode power supply plate connected to the power supply tabs of the negative electrodes of the plurality of laminates are attached; a bottomed cylindrical battery can housing the cell assembly enclosed in the buffer material; and a can lid having electrode terminals and sealing the opening at one end of the battery can, wherein the inside of the buffer material is in contact with the side surface of the cell assembly, the outside of the buffer material is in contact with the inside of the battery can, a positive electrode extension portion is provided on a part of the positive electrode power supply plate which is positioned between the cell assembly and the can lid and connected to the electrode terminals, and a part of the positive electrode power supply plate is positioned between the cell assembly and the buffer material. A solid-state secondary battery, wherein a portion of the negative electrode power supply plate is provided with a negative electrode expandable portion that is positioned between the cell assembly and the bottom surface of the battery can, and a portion of the negative electrode power supply plate is positioned between the cell assembly and the cushioning material.

2. An all-solid-state secondary battery according to claim 1, wherein the cushioning material is an elastic member with a rubber hardness of 20 degrees or less.

3. A solid-state secondary battery according to claim 1, wherein the cushioning material contacts the can lid with one end face and contacts the bottom surface with the other end face in a first direction intersecting with the can lid.

4. An all-solid-state secondary battery according to claim 1, wherein holes are provided on the side surface of the cushioning material.

5. An all-solid-state secondary battery according to claim 1, wherein the positive electrode expandable portion has a shape in which it is folded back at two or more bending points.

6. An all-solid-state secondary battery according to claim 1, wherein the negative electrode expandable portion has a shape in which it is folded back at one or more bending points.

7. An all-solid-state secondary battery according to claim 5 or 6, wherein the straight-line distance from the bending point to the central axis of the battery can is longer than half the radius of the battery can and less than two-thirds the radius of the battery can.

8. An all-solid-state secondary battery according to claim 5 or 6, wherein the angle of the angle corresponding to the bending point is 30 degrees or less.

9. An all-solid-state secondary battery according to claim 1, comprising a housing portion for housing a plurality of the positive electrode, negative electrode, and solid electrolyte layer of the laminate.

10. A method for manufacturing an all-solid-state secondary battery, comprising: a first step of manufacturing a laminate having a positive electrode, a negative electrode, and a solid electrolyte layer interposed between the positive electrode and the negative electrode; a positive electrode tab connected to the positive electrode of the laminate; and a negative electrode tab connected to the negative electrode of the laminate; attaching the positive electrode tab to the positive electrode of the laminate and attaching the negative electrode tab to the negative electrode of the laminate; a second step of stacking a plurality of the laminates to which the positive electrode tab and the negative electrode tab are attached, and attaching a positive electrode power supply plate and a negative electrode power supply plate to the positive electrode tab and the negative electrode tab attached to each of the plurality of laminates to manufacture a cell assembly; a third step of wrapping the sides of the cell assembly with a cushioning material and housing it in a battery can; a fourth step of manufacturing a can lid having electrode terminals; a fifth step of attaching the can lid to one end of the battery can; and a sixth step of performing a chemical conversion treatment.

11. A method for manufacturing an all-solid-state secondary battery, comprising: a first step of manufacturing a laminate having a positive electrode, a negative electrode, and a solid electrolyte layer interposed between the positive electrode and the negative electrode, and housing it in a housing can consisting of a positive electrode casing can and a negative electrode casing can; a second step of subjecting the laminate housed in the housing can to a chemical treatment; a third step of attaching a positive electrode tab to the positive electrode casing can, attaching a negative electrode tab to the negative electrode casing can, stacking a plurality of the laminates housed in the housing can, and attaching a positive electrode power supply plate and a negative electrode power supply plate to the positive electrode tab and the negative electrode tab attached to each of the plurality of positive electrode casing cans and negative electrode casing cans to manufacture a cell assembly; a fourth step of wrapping the cell assembly with a cushioning material and housing it in a battery can; a fifth step of manufacturing a can lid having electrode terminals; and a sixth step of attaching the can lid to one end of the battery can.

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