All-solid-state battery

Abstract

An all-solid-state battery (1) is provided with an electrode laminate (10) and an exterior film (20) that accommodates the electrode laminate (10). Sealing parts (21, 22) of the exterior film (20) are disposed in a direction orthogonal to the lamination direction of the electrode laminate (10), and gaps (11A, 12A, 13A, 14A) are provided between the exterior film (20) and the electrode laminate (10) along edges (11, 12, 13, 14) of the outermost surface of the electrode laminate (10) in the lamination direction.

Description

all solid state battery

[0001] The present invention relates to an all-solid-state battery. This application claims priority to Japanese Patent Application No. 2024-057646, filed on March 29, 2024, the contents of which are incorporated herein by reference.

[0002] In recent years, research and development into all-solid-state batteries has been underway to contribute to energy efficiency, ensuring that more people have access to affordable, reliable, sustainable and advanced energy.

[0003] Since the volume of all-solid-state batteries fluctuates during charging and discharging, a pouch-type laminate that absorbs the displacement caused by the expansion and contraction of the battery cell is required. Currently, there is a structure that absorbs the displacement by wrapping the electrode stack with a laminate film having a cup height that is formed deeper than the thickness of the electrode stack at EOL SOC 100% and setting it to have excess length (see, for example, Patent Document 1).

[0004] JP 2011-71133 A

[0005] It has been confirmed that if the laminate film presses down on the edges of the electrode stack after vacuum sealing, the electrode stack will bend more when the battery cell expands, increasing the stress generated in the solid electrolyte, which will result in a decrease in the robustness of the structural design.

[0006] An aspect of the present invention provides an all-solid-state battery in which a laminate film presses the outermost surface of an electrode laminate, thereby suppressing an increase in bending of the electrode laminate when a battery cell expands. This aspect of the present invention contributes to stabilizing battery performance, improving quality control in the manufacturing process, and improving energy efficiency.

[0007] The present invention provides the following aspects: [1] An all-solid-state battery comprising an electrode laminate and an exterior film that houses the electrode laminate, wherein a sealing portion of the exterior film is disposed in a direction perpendicular to the stacking direction of the electrode laminate, and a gap is provided between the exterior film and the electrode laminate along an edge of the outermost surface of the electrode laminate in the stacking direction.

[0008] By arranging the sealing portion of the exterior film in a direction perpendicular to the stacking direction of the electrode laminate and providing a gap between the exterior film and the electrode laminate along the edge of the outermost surface in the stacking direction of the electrode laminate, even if the exterior film presses against the outermost surface of the electrode laminate when covering the electrode laminate with the exterior film, it is possible to prevent the bending of the electrode laminate from increasing when the electrode laminate expands.

[0009] [2] The all-solid-state battery according to [1], further comprising an insulating layer covering a side surface of the electrode stack in a stacking direction, wherein the void is disposed near the insulating layer.

[0010] The provision of the insulating layer can prevent the electrode laminate and the exterior film from coming into contact with each other and causing a short circuit between them. Furthermore, the provision of the void near the insulating layer can prevent the electrode laminate and the exterior film from coming into contact with each other due to expansion and contraction of the electrode laminate.

[0011] [3] The all-solid-state battery according to [2], wherein an excess length of the exterior film is provided along an edge of the outermost surface in the stacking direction of the electrode stack, and a starting end of the excess length is at an end of the insulating layer on a side of the positive electrode active material layer constituting the electrode stack in a direction perpendicular to the stacking direction of the electrode stack.

[0012] An excess length of the exterior film is provided along the edge of the outermost surface in the stacking direction of the electrode laminate, and the starting end of the excess length is at the end of the insulating layer on the side of the positive electrode active material layer that constitutes the electrode laminate, in a direction perpendicular to the stacking direction of the electrode laminate.Therefore, even if the exterior film and the insulating layer come into contact due to expansion and contraction of the electrode laminate, a short circuit between the electrode laminate and the exterior film can be prevented.

[0013] [4] The all-solid-state battery according to [3], wherein a starting end of the excess length is located at a position from an end of the insulating layer on a side of a positive electrode active material layer constituting the electrode stack to a position at least ⅓ and not more than ½ of the length of the insulating layer in a direction perpendicular to the stacking direction of the electrode stack.

[0014] Since the starting end of the excess length is located at a position between 1 / 3 and 1 / 2 of the length of the insulating layer from the end of the insulating layer on the positive electrode active material layer side that constitutes the electrode stack in a direction perpendicular to the stacking direction of the electrode stack, it is possible to prevent peeling force from being applied to the sealing portion due to expansion and contraction of the electrode stack.

[0015] [5] The all-solid-state battery according to any one of [1] to [4], wherein the exterior film has a housing portion that houses the electrode stack and the sealing portion formed on the periphery of the housing portion, the sealing portion includes a folded portion formed by folding the exterior film in half, and the folded portion has a portion extending along the stacking direction of the electrode stack.

[0016] The exterior film has a storage section that stores the electrode stack and a sealing section formed on the periphery of the storage section, and the sealing section includes a folded section formed by folding the exterior film in half, and the folded section has a portion that extends along the stacking direction of the electrode stack, so that it is possible to prevent peeling force from being applied to the sealing section due to expansion and contraction of the electrode stack.

[0017] [6] The all-solid-state battery according to any one of [1] to [5], wherein a buffer material is disposed inside the gap and on the outermost surface in the stacking direction of the electrode stack.

[0018] By providing the buffer material, it is possible to prevent the electrode stack from being damaged when an external force is applied.

[0019] [7] The all-solid-state battery according to [6], further comprising an insulating layer covering a side surface of the electrode stack in a stacking direction, wherein the buffer material is disposed in a region within ⅓ of the length of the insulating layer from an end of the insulating layer on a side of a positive electrode active material layer constituting the electrode stack in a direction perpendicular to the stacking direction of the electrode stack.

[0020] By arranging the buffer material in a region within 1 / 3 of the length of the insulating layer from the end of the insulating layer on the side of the positive electrode active material layer that constitutes the electrode stack, damage to the electrode stack can be suppressed when an external force is applied.

[0021] According to an aspect of the present invention, it is possible to provide an all-solid-state battery in which the laminate film presses the outermost surface of the electrode laminate, thereby suppressing an increase in bending of the electrode laminate when the battery cell expands.

[0022] FIG. 1 is a cross-sectional view showing an all-solid-state battery according to one embodiment of the present invention.

[0023] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0024] [All-Solid-State Battery] Fig. 1 is a cross-sectional view showing an all-solid-state battery according to one embodiment of the present invention. Note that the drawings used in the following description may show characteristic portions enlarged for convenience in order to make the characteristics easier to understand, and the dimensional ratios of each component are not limited to those shown.

[0025] 1 , the all-solid-state battery 1 of this embodiment includes an electrode laminate 10 and an exterior film 20. The exterior film 20 covers the outer surface 10 a of the electrode laminate 10 and houses the electrode laminate 10.

[0026] The electrode stack 10 includes a positive electrode, a negative electrode, and a solid electrolyte layer.

[0027] The exterior film 20 has a housing portion 10A that houses the electrode stack 10, and two sealing portions 21, 22 that are formed on the periphery of the housing portion 10A and are arranged in a direction perpendicular to the stacking direction of the electrode stack 10. That is, the sealing portions 21, 22 are arranged to face the side surfaces 10b, 10c, respectively, in the stacking direction of the electrode stack 10. The sealing portions 21, 22 include folded portions 21A, 22A that are formed by folding the exterior film 20 in half. The folded portions 21A, 22A preferably have portions that extend along the stacking direction of the electrode stack 10. This makes it possible to suppress peeling forces from being applied to the sealing portions 21, 22 due to expansion and contraction of the electrode stack 10.

[0028] Along edge portions 11, 12, 13, and 14 of the outermost surface in the stacking direction of the electrode laminate 10 (upper surface 10d in the stacking direction of the electrode laminate 10 and lower surface 10e in the stacking direction of the electrode laminate 10), gaps 11A, 12A, 13A, and 14A are provided between the outermost surface edge portions 11, 12, 13, and 14 of the electrode laminate 10 in the stacking direction and the exterior film 20. By providing the gaps 11A, 12A, 13A, and 14A, excess lengths 23, 24, 25, and 26 of the exterior film 20 exist along the outermost surface edge portions 11, 12, 13, and 14 of the electrode laminate 10 in the stacking direction.

[0029] The excess lengths 23, 24, 25, and 26 of the exterior film 20 refer to portions of the exterior film 20 that are not in contact with the electrode stack 10 and are separated from the electrode stack 10. The lengths of the excess lengths 23, 24, 25, and 26, i.e., the lengths of the exterior film 20 that are separated from the electrode stack 10, are preferably 1 mm or more and 3 mm or less, and more preferably 1 mm or more and 1.5 mm or less. When the lengths of the excess lengths 23, 24, 25, and 26 are within the above ranges, it is possible to prevent the entire exterior film 20 from being stretched or peeling forces from being applied to the sealing portions 21 and 22 due to expansion and contraction of the electrode stack 10. Furthermore, the length of the exterior film 20 that is separated from the electrode stack 10 is the maximum length of the gaps 11A, 12A, 13A, and 14A in the thickness direction of the all-solid-state battery 1.

[0030] The all-solid-state battery 1 preferably includes an insulating layer 30 that covers the side surfaces 10b and 10c of the electrode stack 10 in the stacking direction. Furthermore, the voids 11A, 12A, 13A, and 14A are preferably disposed near the insulating layer 30. In other words, the excess lengths 23, 24, 25, and 26 of the exterior film 20 are preferably disposed near the insulating layer 30. By providing the insulating layer 30, it is possible to prevent the electrode stack 10 and the exterior film 20 from coming into contact with each other and short-circuiting the electrode stack 10 and the exterior film 20. Furthermore, by disposing the voids 11A, 12A, 13A, and 14A near the insulating layer 30, it is possible to prevent the electrode stack 10 and the exterior film 20 from coming into contact with each other due to expansion and contraction of the electrode stack 10.

[0031] The starting ends of the excess lengths 23, 24, 25, and 26 are preferably located at the end of the insulating layer 30 on the side of the positive electrode active material layer that constitutes the electrode stack 10, in a direction perpendicular to the stacking direction of the electrode stack 10. It is more preferable that the starting ends of the excess lengths 23, 24, 25, and 26 are located at a position that is from one-third to one-half of the length of the insulating layer 30, in a direction perpendicular to the stacking direction of the electrode stack 10, from the end of the insulating layer 30 on the side of the positive electrode active material layer that constitutes the electrode stack 10.

[0032] It is preferable that buffer materials 41 and 42 are arranged on the outermost surfaces in the stacking direction of the electrode stack 10 (upper surface 10d and lower surface 10e in the stacking direction of the electrode stack 10) inside the gaps 11A, 12A, 13A, and 14A, in other words, inside the excess lengths 23, 24, 25, and 26 of the exterior film 20. By arranging the buffer materials 41 and 42, it is possible to prevent the electrode stack 10 from being damaged when an external force is applied.

[0033] The buffer materials 41, 42 are preferably arranged in a region within 1 / 3 of the length of the insulating layer 30 from the end of the insulating layer 30 on the positive electrode active material layer side that constitutes the electrode stack 10, in a direction perpendicular to the stacking direction of the electrode stack 10.

[0034] (Positive Electrode) The positive electrode is formed by laminating a first current collector layer and a first active material layer containing at least a positive electrode active material. In this embodiment, the positive electrode has the first current collector layer and the first active material layer formed on both main surfaces of the first current collector layer.

[0035] The first current collector layer is preferably composed of at least one material with high conductivity. Examples of highly conductive materials include metals or alloys containing at least one of silver (Ag), palladium (Pd), gold (Au), platinum (Pt), aluminum (Al), chromium (Cr), and nickel (Ni), or non-metals such as carbon (C). Considering both high conductivity and manufacturing costs, aluminum, nickel, or stainless steel is preferred. Furthermore, aluminum is less likely to react with the positive electrode active material and electrolyte. Therefore, using aluminum for the first current collector layer can reduce the internal resistance of the battery.

[0036] The first current collector layer may have, for example, a foil, plate, mesh, nonwoven fabric, foam, etc. In order to improve adhesion to the first active material layer 32, carbon or the like may be disposed on the surface of the first current collector layer, or the surface may be roughened.

[0037] The first active material layer contains a positive electrode active material that transfers lithium ions and electrons. The positive electrode active material is not particularly limited as long as it can reversibly release and absorb lithium ions and transport electrons, and any known positive electrode active material that can be used in the positive electrode of a lithium ion battery can be used. For example, lithium cobalt oxide (LiCoO ２ ), lithium nickel oxide (LiNiO ２ ), lithium manganese oxide (LiMn ２ O ４ ), solid solution oxide (Li ２ MnO ３ -LiMO ２ (M=Co, Ni, etc.), lithium-manganese-nickel-cobalt oxide (LiNi ｘ Mn ｙ Co ｚ O ２ , x+y+z=1), olivine-type lithium phosphate oxide (LiFePO ４ ) and other composite oxides; conductive polymers such as polyaniline and polypyrrole; Li ２ S, CuS, Li-Cu-S compound, TiS ２ , FeS, MoS ２ , sulfides such as Li—Mo—S compounds, mixtures of sulfur and carbon, etc. The positive electrode active material may be composed of one kind of the above materials alone, or two or more kinds of them.

[0038] The first active material layer contains an electrolyte that transfers lithium ions to and from the positive electrode active material. The electrolyte is not particularly limited as long as it has lithium ion conductivity, and materials commonly used in lithium ion batteries can be used. Examples of electrolytes include inorganic solid electrolytes such as sulfide solid electrolyte materials, oxide solid electrolyte materials, halide solid electrolytes, and lithium-containing salts, polymer-based solid electrolytes such as polyethylene oxide, and gel-based solid electrolytes containing lithium-containing salts and lithium-ion conductive ionic liquids. Among these, sulfide solid electrolyte materials are preferred from the viewpoints of high lithium ion conductivity, structural formability by pressing, and interfacial bonding. The electrolyte may be composed of one or more of the above materials. The electrolyte contained in the first active material layer may be the same material as or different from the electrolyte contained in the second active material layer or the solid electrolyte layer.

[0039] The first active material layer may contain a conductive additive to improve the conductivity of the positive electrode. Examples of the conductive additive include carbon blacks such as acetylene black and ketjen black; carbon fibers; vapor-grown carbon fibers; graphite powder; and carbon materials such as carbon nanotubes. The conductive additive may be composed of one or more of the above materials.

[0040] The first active material layer may also contain a binder that functions to bind the positive electrode active materials together and between the positive electrode active material and the first current collector layer.

[0041] In this embodiment, the first active material layer is formed on both main surfaces of the first current collector layer, but this is not limited thereto, and the first active material layer may be formed on only one main surface of the first current collector layer. Furthermore, when the positive electrode is a single-sided coated electrode, a laminated positive electrode in which two positive electrodes are stacked so that their current collector surfaces face each other may be used as a double-sided coated electrode. Furthermore, when the first current collector layer has a three-dimensional porous structure such as a mesh, nonwoven fabric, or foam, the first current collector layer may be provided integrally with the first active material layer.

[0042] The first current collector layer is assembled at one end of the all-solid-state battery in the width direction. The first active material layer is in contact with the solid electrolyte layer and may contain sulfide contained in the solid electrolyte layer.

[0043] (Negative Electrode) The negative electrode is formed by stacking a second current collector layer and a second active material layer containing at least a negative electrode active material. In this embodiment, the negative electrode has the second current collector layer and second active material layers formed on both main surfaces of the second current collector layer and containing a negative electrode active material and an electrolyte.

[0044] The second current collector layer contains at least copper (Cu). Like the first current collector layer, the second current collector layer may contain a material other than copper that has high conductivity. Examples of highly conductive materials other than copper include metals or alloys containing at least one of silver (Ag), palladium (Pd), gold (Au), platinum (Pt), chromium (Cr), and nickel (Ni), or non-metals such as carbon (C). Considering both high conductivity and manufacturing costs, nickel or stainless steel is preferred as the material other than copper. Furthermore, stainless steel is less likely to react with the positive electrode active material, negative electrode active material, and electrolyte. Therefore, using stainless steel for the second current collector layer can reduce the manufacturing cost of the battery.

[0045] The second current collector layer may have, for example, a foil, plate, mesh, nonwoven fabric, foam, etc. In order to improve adhesion to the second active material layer, carbon or the like may be disposed on the surface of the second current collector layer, or the surface may be roughened.

[0046] The second active material layer contains a negative electrode active material that donates and receives lithium ions and electrons. The negative electrode active material is not particularly limited as long as it is a material that can reversibly release and absorb lithium ions and transport electrons, and known negative electrode active materials that can be used for the negative electrode of a lithium ion battery can be used. Examples of such materials include carbonaceous materials such as natural graphite, artificial graphite, resin carbon, carbon fiber, activated carbon, hard carbon, and soft carbon; alloy-based materials mainly composed of tin, tin alloys, silicon, silicon alloys, gallium, gallium alloys, indium, indium alloys, aluminum, and aluminum alloys; conductive polymers such as polyacene, polyacetylene, and polypyrrole; metallic lithium; lithium titanium composite oxides (e.g., Li ４ Ti ５ O １２ These negative electrode active materials may be composed of one kind of the above materials alone or two or more kinds of them.

[0047] The second active material layer contains an electrolyte that transfers lithium ions to and from the negative electrode active material. The electrolyte is not particularly limited as long as it has lithium ion conductivity, and materials commonly used in lithium ion batteries can be used. Examples of the electrolyte include inorganic solid electrolytes such as sulfide solid electrolyte materials, oxide solid electrolyte materials, halide solid electrolytes, and lithium-containing salts, polymer-based solid electrolytes such as polyethylene oxide, and gel-based solid electrolytes containing lithium-containing salts and lithium-ion conductive ionic liquids. The electrolyte may be composed of one or more of the above materials. The electrolyte contained in the second active material layer may be the same as or different from the electrolyte contained in the first active material layer or the solid electrolyte layer.

[0048] The second active material layer may contain a conductive additive, a binder, etc. These materials are not particularly limited, and may be, for example, the same materials as those used in the first active material layer described above.

[0049] In this embodiment, the second active material layer is formed on both main surfaces of the second current collector layer, but this is not limiting, and the second active material layer may be formed on only one main surface of the second current collector layer. Furthermore, when the second current collector layer has a three-dimensional porous structure such as a mesh, nonwoven fabric, or foam, the second current collector layer may be provided integrally with the second active material layer.

[0050] (Solid Electrolyte Layer) The solid electrolyte layer is disposed between the first active material layer and the second active material layer.

[0051] The electrolyte is not particularly limited as long as it has lithium ion conductivity and insulating properties, and materials commonly used in lithium ion batteries can be used. Examples include inorganic solid electrolytes such as sulfide solid electrolyte materials, oxide solid electrolyte materials, halide solid electrolytes, and lithium-containing salts, polymer-based solid electrolytes such as polyethylene oxide, and gel-based electrolytes containing lithium-containing salts and lithium ion-conducting ionic liquids. Among these, sulfide solid electrolyte materials are preferred from the viewpoints of high lithium ion conductivity, structural formability by pressing, and interfacial bonding. The form of the electrolyte material is not particularly limited, and examples thereof include particulate forms.

[0052] The solid electrolyte layer may contain an adhesive to impart mechanical strength and flexibility.

[0053] The solid electrolyte layer may be in the form of a sheet having a porous substrate and a solid electrolyte supported on the porous substrate. The form of the porous substrate is not particularly limited, and examples thereof include woven fabric, nonwoven fabric, mesh cloth, porous membrane, expanded sheet, and punched sheet. Among these forms, nonwoven fabric is preferred from the viewpoint of handleability, which allows for a higher loading of the solid electrolyte.

[0054] The porous substrate is preferably made of an insulating material, which can improve the insulating properties of the solid electrolyte layer. Examples of insulating materials include resin materials such as nylon, polyester, polyethylene, polypropylene, polytetrafluoroethylene, ethylene-tetrafluoroethylene copolymer, polyvinylidene fluoride, polyvinylidene chloride, polyvinyl chloride, polyurethane, vinylon, polybenzimidazole, polyimide, polyphenylene sulfite, polyether ether ketone, cellulose, and acrylic resin; natural fibers such as hemp, wood pulp, and cotton linter; and glass.

[0055] (Exterior Film) The exterior film 20 is a laminated film having an inner resin layer, a metal layer, and an outer resin layer. Examples of resins constituting the inner and outer resin layers include polyester resins such as polyethylene terephthalate (PET). The metal layer is made of, for example, aluminum foil.

[0056] (Insulating Layer) The insulating material constituting the insulating layer 30 is not particularly limited, but examples thereof include high-purity alumina.

[0057] (Buffer Material) The buffer materials 41 and 42 are not particularly limited, but may be made of a material having thermal conductivity and elasticity, for example.

[0058] According to the all-solid-state battery 1 of this embodiment, the sealing portions 21, 22 of the exterior film 20 are arranged in a direction perpendicular to the stacking direction of the electrode stack 10, and gaps 11A, 12A, 13A, 14A are provided between the exterior film 20 and the outermost edge portions 11, 12, 13, 14 of the electrode stack 10 in the stacking direction, along the outermost edge portions 11, 12, 13, 14 of the electrode stack 10 in the stacking direction. This makes it possible to suppress an increase in bending of the electrode stack 10 when the electrode stack 10 expands, even if the exterior film 20 presses against the outermost surface of the electrode stack 10 when the electrode stack 10 is covered with the exterior film 20.

[0059] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments, and various modifications and changes are possible within the scope of the gist of the present invention as described in the claims.

[0060] REFERENCE SIGNS LIST 1 all-solid-state battery 10 electrode laminate 11A, 12A, 13A, 14A gap 20 exterior film 23, 24, 25, 26 excess length 30 insulating layer 41, 42 cushioning material

Claims

1. An all-solid-state battery comprising an electrode laminate and an exterior film that houses the electrode laminate, wherein a sealing portion of the exterior film is arranged in a direction perpendicular to the lamination direction of the electrode laminate, and a gap is provided between the exterior film and the electrode laminate along the edge of the outermost surface of the electrode laminate in the lamination direction.

2. The all-solid-state battery according to claim 1, further comprising an insulating layer covering a side surface of the electrode stack in the stacking direction, and the void is located near the insulating layer.

3. The all-solid-state battery according to claim 2, wherein an excess length of the exterior film is provided along the edge of the outermost surface in the stacking direction of the electrode stack, and a starting end of the excess length is located at an end of the insulating layer on the side of the positive electrode active material layer that constitutes the electrode stack in a direction perpendicular to the stacking direction of the electrode stack.

4. The all-solid-state battery according to claim 3, wherein the starting end of the excess length is located at a position from one-third to one-half of the length of the insulating layer, in a direction perpendicular to the stacking direction of the electrode stack, from the end of the insulating layer on the side of the positive electrode active material layer that constitutes the electrode stack.

5. The all-solid-state battery according to claim 1, wherein the exterior film has a housing section that houses the electrode stack and the sealing section formed on the periphery of the housing section, the sealing section including a folded section formed by folding the exterior film in half, and the folded section has a portion that extends along the stacking direction of the electrode stack.

6. The all-solid-state battery according to claim 1, wherein a buffer material is disposed inside the gap and on the outermost surface in the stacking direction of the electrode stack.

7. The all-solid-state battery according to claim 6, further comprising an insulating layer covering a side surface of the electrode stack in a stacking direction, wherein the buffer material is disposed in a region within one-third of the length of the insulating layer from the end of the insulating layer on the side of the positive electrode active material layer constituting the electrode stack in a direction perpendicular to the stacking direction of the electrode stack.

Images