Can-type battery and manufacturing method of can-type battery

Abstract

To provide a can-type battery having a mechanism that has a large holding force of an electrode stack against a cell, absorbs dimensional tolerances and geometric tolerances of the electrode stack when pressure is applied to the electrode stack, and acts as a cushion to prevent damage to the electrode stack.SOLUTION: A can-type battery 100 includes a can body 110, an electrode stack 120 housed within the can body 110 and composed of a positive electrode 140, a negative electrode 150, and an electrolyte layer 160, and a holding member 130 disposed in the space between the can body 110 and the electrode stack 120 to hold the electrode stack 120 within the can body 110. The holding member 130 is a packing member having hollow beads made of a thermoplastic resin, a metal layer formed on the outer surfaces of the hollow beads, and a fluid contained in the internal spaces of the hollow beads, and also having metal-coated hollow beads in which a second volume after heating is larger than a first volume before heating or a rubber elastomer, the metal-coated hollow beads being contained within the rubber elastomer.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a can-type battery and a method for manufacturing a can-type battery. [Background technology]

[0002] In a sealed battery, an electrode stack consisting of a positive electrode, a negative electrode, and an electrolyte layer is housed in a cylindrical cell. In such a battery, a pressure spacer that applies pressure to the electrode stack in the stacking direction is housed in the cell, and the pressure spacer holds the electrode stack within the cell by deforming to increase the volume it occupies within the cell (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 8-83624 Summary of the Invention [Problem to be solved by the invention]

[0004] The pressure spacer has no mechanism for absorbing the dimensional tolerances and geometric tolerances of the electrode stack, and therefore has the problem of the risk of damaging the electrode stack.

[0005] The present invention has been made in consideration of the above circumstances, and aims to provide a can-type battery that has a large holding force of the electrode stack against the cell, has a mechanism that absorbs dimensional tolerances and geometric tolerances of the electrode stack when pressure is applied to the electrode stack, and has a cushioning mechanism that prevents damage to the electrode stack, thereby contributing to stabilizing battery performance, improving quality control in the manufacturing process, and ultimately improving energy efficiency. [Means for solving the problem]

[0006] In order to achieve the above object, the present invention provides the following means. [1] A can body, an electrode stack housed in a can body and composed of a positive electrode, a negative electrode, and an electrolyte layer; a holding member disposed in a gap between the can body and the electrode stack, and holding the electrode stack within the can body; Equipped with The holding member is a can-type battery, wherein the holding member is a filling member having hollow beads made of a thermoplastic resin, a metal layer formed on the outer surface of the hollow beads, and a fluid contained in the internal space of the hollow beads, and the second volume after heating is larger than the first volume before heating, or the holding member is a filling member having a rubber elastic body and the metal-coated hollow beads contained within the rubber elastic body.

[0007] When heated, the holding member expands, thereby applying pressure to the electrode stack in the stacking direction. When metal-coated hollow beads are used as the holding member, the multiple metal-coated hollow beads deform or move from high-stress areas to low-stress areas during expansion, preventing stress concentration at the contact points between the metal-coated hollow beads and the electrode stack, thereby preventing damage to the electrode stack. Furthermore, the deformation of the metal-coated hollow beads can mitigate the expansion or contraction of the electrode stack during battery charging and discharging. Specifically, when the electrode stack expands during battery charging, the surrounding metal-coated hollow beads press down on the electrode stack, reducing the expansion rate. Furthermore, the multiple metal-coated hollow beads can accommodate dimensional and geometric tolerances of the electrode stack, thereby preventing damage to the electrode stack. When a rubber elastic body is used as the holding member, the expansion force of the rubber elastic body can absorb variations in the expansion rate of individual metal-coated hollow beads, allowing for the formation of a packing member containing more uniform metal-coated hollow beads. Pressurization by the uniform packing member further improves the holding force of the electrode stack. Furthermore, by covering the electrode surfaces of the electrode laminate with a rubber elastic material before placing the electrode laminate inside the can body, the electrode surfaces of the electrode laminate will not come into direct contact with the edges or walls of the can body, and when an impact is applied, the rubber elastic material and the metal-coated hollow beads will act as a cushion, thereby preventing damage to the electrode laminate. When heated, the hollow beads expand. For example, if a metal-coated hollow bead placed in a gap between two members is heated, the expanded metal-coated hollow bead will pressurize the two members and hold one member against the other. By including a material in the internal space of the hollow beads that causes the hollow beads to expand by a phase change, the hollow beads can easily expand when heated. The filling member can stand on its own because it has a rubber elastic body and metal-coated hollow beads contained within the rubber elastic body. Furthermore, because the metal-coated hollow beads are contained within the rubber elastic body, the rubber elastic body can absorb variations in the expansion coefficient of the individual metal-coated hollow beads, resulting in the formation of a more uniform filling member.

[0008] [2] The can-type battery according to [1], wherein an insulator is disposed between the electrode stack and the holding member, or between the can body and the holding member.

[0009] By disposing an insulator at least either between the electrode stack and the holding member or between the can body and the holding member, the insulation between the holding member and the electrode stack and the can body can be improved.

[0010] [3] The can-type battery according to [2], wherein the insulator is a film or sheet made of at least one material selected from the group consisting of polyethylene, polypropylene, polyethylene terephthalate, polyamide, polyamideimide, polyvinylidene fluoride, and polytetrafluoroethylene.

[0011] By using an insulator made of a resin with appropriate hardness and flexibility, the insulator can function as a buffer material and protect the electrode stack. However, if the resin is too hard, it may lead to damage to the electrode stack.

[0012] [4] The can-type battery according to [1], wherein the electrolyte layer is a solid electrolyte layer.

[0013] When the electrolyte layer is a solid electrolyte layer, the electrode stack is made up entirely of solids, the electrode stack can stand on its own inside the can body, and after the electrode stack is inserted inside the can body, metal-coated hollow beads or the like can be placed inside.

[0014] [5] The can-type battery according to [1], wherein the fluid is nitrogen gas.

[0015] If the fluid is nitrogen gas, when a battery equipped with metal-coated hollow beads rises above a predetermined temperature, the metal-coated hollow beads will burst, filling the battery with nitrogen and blocking oxygen, thereby delaying the time until ignition and suppressing the spread of fire. Furthermore, when metal-coated hollow beads are used in can-type batteries, there is ample space between the can body and the electrode stack (there is a little space), so when the can-type battery experiences thermal runaway and part of the stack expands, the hollow beads can move to another location to avoid stress concentration at the expanded area, making it possible to respond to some thermal runaway and improving safety.

[0016] [6] The can-type battery according to [1], wherein the hollow beads have a temperature at which they expand when heated of 100°C or higher.

[0017] When heated to 100°C or higher, the fluid in the internal space of the hollow beads expands, causing the hollow beads to expand.

[0018] [7] The can-type battery according to [1], wherein the metal layer contains at least one selected from copper, aluminum, nickel, tin, silver, and gold.

[0019] By including at least one metal selected from copper, aluminum, nickel, tin, silver, and gold in the metal layer, the heat dissipation and thermal conductivity of the metal layer are improved, temperature rise can be suppressed, and when the metal-coated hollow beads are heated, heat is transferred evenly throughout the metal-coated hollow beads. Furthermore, the rigidity of the metal-coated hollow beads is also increased. For example, when a metal-coated hollow bead placed in a gap between two components is heated, the expanded metal-coated hollow bead can pressurize the two components and hold one component against the other.

[0020] [8] The can-type battery according to [1], wherein the thickness of the metal layer is defined by the following formula (1): (Thickness of metal layer) / (Thickness of outer shell of hollow bead)≦{(Young's modulus of thermoplastic resin layer) / (Young's modulus of metal layer)} 1 / 3 (1)

[0021] By defining the thickness of the metal layer by the above formula (1), the metal layer also elongates as the hollow beads expand upon heating, allowing the diameter of the beads to be increased without the metal layer peeling off from the hollow beads.

[0022] [9] The can-type battery according to [1], wherein the hollow beads have an average particle size (D50) of 50 μm or less before heating and an average particle size (D50) of more than 50 μm and 200 μm or less after heating.

[0023] If the average particle size (D50) of hollow beads before heating exceeds 50 μm, for example, when multiple metal-coated hollow beads placed in a gap between two members are heated, the gaps between the expanded metal-coated hollow beads will become larger, and the pressure exerted by the expanded metal-coated hollow beads on the two members will become uneven.

[0024]

[10] The can-type battery according to [1], wherein the rubber elastic body is made of urethane rubber or silicone rubber.

[0025] The rubber elastic body is made of urethane rubber or silicone rubber, and therefore, the metal-coated hollow beads can be prevented from being crushed within the rubber elastic body.

[0026]

[11] The can-type battery according to [1], wherein the elastic modulus of the rubber elastic body is lower than the elastic modulus of the metal-coated hollow beads.

[0027] Since the elastic modulus of the rubber elastic body is lower than that of the metal-coated hollow beads, the metal-coated hollow beads can be prevented from being crushed within the rubber elastic body.

[0028]

[12] The can-type battery according to

[10] or

[11] , wherein the thickness of the rubber elastic body is 50 μm or more.

[0029] If the thickness of the rubber elastomer is less than 50 μm, the rubber elastomer cannot stand on its own and will break or wrinkle, which will cause the rubber elastomer to have an uneven thickness, making it impossible to apply uniform pressure to the laminate when heated, leading to damage to the laminate.

[0030]

[13] The can-type battery according to [1], wherein the content of the metal-coated hollow beads in the filling member is 40% by volume or more and 80% by volume or less.

[0031] If the content of metal-coated hollow beads in the filling member is less than 40% by volume, they cannot follow the expansion force of the rubber elastomer, and the metal-coated hollow beads cannot expand within the rubber elastomer. If the content of metal-coated hollow beads in the filling member is more than 80% by volume, the amount of rubber elastomer becomes too small, and the filling member cannot stand on its own. Furthermore, the expansion rate of the filling member can be controlled by adjusting the content of metal-coated hollow beads.

[0032]

[14] A step of disposing an electrode stack composed of a positive electrode, a negative electrode, and an electrolyte layer inside the can body; disposing a retaining member in a gap between the can body and the electrode stack; a step of heating the holding member to expand it, pressurizing the electrode stack in a stacking direction with the holding member, and holding the electrode stack in the can body with the holding member; and The method for manufacturing a can-type battery, wherein the holding member is a filling member having metal-coated hollow beads or a rubber elastic body and the metal-coated hollow beads contained within the rubber elastic body, the filling member having hollow beads made of a thermoplastic resin, a metal layer formed on the outer surface of the hollow beads, and a fluid contained in the internal space of the hollow beads, the second volume after heating being larger than the first volume before heating, and the increase in volume pressurizing the stack in the stacking direction.

[0033] When heated, the metal-coated hollow beads expand, thereby applying pressure to the electrode stack in the stacking direction. When the beads expand, they deform and move from areas of high stress concentration to areas of low stress, preventing stress from concentrating at the contact points between the metal-coated hollow beads and the electrode stack, thereby preventing damage to the electrode stack. Furthermore, the deformation of the metal-coated hollow beads can mitigate expansion or contraction of the electrode stack during battery charging and discharging. Furthermore, the multiple metal-coated hollow beads can accommodate dimensional and geometric tolerances of the electrode stack, preventing damage to the electrode stack.

[0034]

[15] The method for manufacturing a can-type battery according to

[14] , further comprising, before the step of arranging the electrode stack, a step of arranging an insulator at least one between the electrode stack and the holding member and between the can body and the holding member.

[0035] By placing an insulator between the electrode stack and the holding member or between the can body and the holding member before placing the electrode stack, damage to the electrode stack can be prevented when placing the electrode stack inside the can body.

[0036]

[16] The method for manufacturing a can-type battery according to

[14] , further comprising the step of arranging an insulator that covers the electrode surfaces of the electrode laminate before the step of arranging the electrode laminate.

[0037] By arranging an insulator that covers the electrode surfaces of the electrode stack before arranging the electrode stack, damage to the electrode stack can be prevented when the electrode stack is arranged inside the can body. [Effects of the Invention]

[0038] According to the present invention, it is possible to provide a can-type battery that has a large holding force of the electrode stack against the cell, has a mechanism that absorbs dimensional tolerances and geometric tolerances of the electrode stack when pressure is applied to the electrode stack, and has a mechanism that acts as a cushion to prevent damage to the electrode stack. [Brief explanation of the drawings]

[0039] [Figure 1] 1 is a cross-sectional view showing a can-type battery according to a first embodiment of the present invention. [Figure 2] FIG. 3 is a cross-sectional view showing a metal-coated hollow bead according to a second embodiment of the present invention. [Figure 3] FIG. 10 is a cross-sectional view showing a filling member according to a third embodiment of the present invention. [Figure 4] FIG. 10 is a cross-sectional view showing a can-type battery according to a fourth embodiment of the present invention. [Figure 5] FIG. 1 is a diagram showing the relationship between the heating temperature of metal-coated hollow beads and the expansion coefficient of the metal-coated hollow beads in Examples. DETAILED DESCRIPTION OF THE INVENTION

[0040] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0041] [Can-type battery] 1 is a cross-sectional view showing a can-type battery according to a first embodiment of the present invention. Note that the drawings used in the following description may show characteristic parts 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.

[0042] 1 , a can-type battery 100 of this embodiment includes a can body 110, an electrode stack 120, and a holding member 130. The electrode stack 120 is housed in the can body 110. The holding member 130 is disposed in a gap 113 between the can body 110 and the electrode stack 120, and holds the electrode stack 120 within the can body 110.

[0043] The can body 110 is a housing that houses the electrode stack 120 and the holding member 130. The can body 110 has a cylindrical main body 111 having a bottom surface 111a, and a lid body 112 for closing the opening of the main body 111.

[0044] The electrode stack 120 is composed of a positive electrode 140 , a negative electrode 150 , and an electrolyte layer 160 .

[0045] The positive electrodes 140 and negative electrodes 150 are alternately stacked with the electrolyte layer 160 interposed therebetween. The can-type battery 100 is charged and discharged by the exchange of lithium ions between the positive electrodes 140 and the negative electrodes 150 via the electrolyte layer 160.

[0046] (positive electrode) The positive electrode 140 is formed by laminating a first current collector layer 141 and a first active material layer 142 containing at least a positive electrode active material. In this embodiment, the positive electrode 140 has the first current collector layer 141 and the first active material layers 142 formed on both main surfaces of the first current collector layer 141.

[0047] The first current collector layer 141 is preferably made of at least one material with high electrical 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), as well as non-metals such as carbon (C). Considering manufacturing costs in addition to high conductivity, aluminum, nickel, or stainless steel is preferred. Furthermore, aluminum does not easily react with the positive electrode active material and electrolyte. Therefore, using aluminum for the first current collector layer 141 can reduce the internal resistance of the battery.

[0048] The first current collector layer 141 may have, for example, a foil, a plate, a mesh, a nonwoven fabric, a foam, etc. In order to improve adhesion to the first active material layer 142, carbon or the like may be disposed on the surface of the first current collector layer 141, or the surface may be roughened.

[0049] The first active material layer 142 contains a positive electrode active material that donates and receives lithium ions and electrons. The positive electrode active material is not particularly limited as long as it can reversibly absorb and release lithium ions and transport electrons, and known positive electrode active materials that can be used for the positive electrode of a lithium ion battery can be used. For example, lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), lithium manganese oxide (LiMn2O4), solid solution oxide (Li2MnO3-LiMO2 (M=Co, Ni, etc.)), lithium manganese-nickel-cobalt oxide (LiNi x Mn y Co z O2, x+y+z=1), composite oxides such as olivine-type lithium phosphate (LiFePO4); conductive polymers such as polyaniline and polypyrrole; sulfides such as Li2S, CuS, Li-Cu-S compounds, TiS2, FeS, MoS2, and 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 may be composed of two or more kinds.

[0050] The first active material layer 142 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 generally 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. Of these, sulfide solid electrolyte materials are preferred from the standpoints of high lithium ion conductivity, structural formability by pressing, and interfacial bonding. The electrolyte may be composed of one kind of the above materials alone or two or more kinds of them. The electrolyte contained in the first active material layer 142 may be the same material as the electrolyte contained in the second active material layer 152 or the electrolyte layer 160, or may be a different material.

[0051] The first active material layer 142 may contain a conductive additive from the viewpoint of improving the conductivity of the positive electrode 140. The conductive additive may be any conductive additive that is generally usable in lithium-ion batteries. Examples include carbon black such as acetylene black and Ketjen black; carbon fiber; vapor-grown carbon fiber; graphite powder; and carbon materials such as carbon nanotubes. The conductive additive may be composed of one or more of the above materials.

[0052] The first active material layer 142 may also contain a binder that functions to bind the positive electrode active materials together and the positive electrode active materials and the first current collector layer 141 together.

[0053] In this embodiment, the first active material layer 142 is formed on both main surfaces of the first current collector layer 141, but this is not limiting, and the first active material layer 142 may be formed on only one main surface of the first current collector layer 141. Furthermore, when the positive electrode 140 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 141 has a three-dimensional porous structure such as a mesh, nonwoven fabric, or foam, the first current collector layer 141 may be provided integrally with the first active material layer 142.

[0054] The first current collector layers 141 are assembled at one end of the can-type battery 100 in the width direction. The first active material layer 142 is in contact with the electrolyte layer 160 and may therefore contain sulfides contained in the electrolyte layer 160 .

[0055] (Negative electrode) The negative electrode 150 is formed by stacking a second current collector layer 151 and a second active material layer 152 containing at least a negative electrode active material. In this embodiment, the negative electrode 150 has the second current collector layer 151 and second active material layers 152 formed on both main surfaces of the second current collector layer 151 and containing a negative electrode active material and an electrolyte.

[0056] The second current collector layer 151 contains at least copper (Cu). Like the first current collector layer 141, the second current collector layer 151 may contain a material other than copper that has high conductivity. Examples of materials other than copper that have high conductivity 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 not only high conductivity but also 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 151 can reduce the manufacturing costs of the battery.

[0057] The second current collector layer 151 may have, for example, a foil, a plate, a mesh, a nonwoven fabric, a foam, etc. In order to improve adhesion to the second active material layer 152, carbon or the like may be disposed on the surface of the second current collector layer 151, or the surface may be roughened.

[0058] The second active material layer 152 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 absorb and release 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 (for example, Li4Ti5O 12 These negative electrode active materials may be composed of one kind of the above materials alone, or two or more kinds of them.

[0059] The second active material layer 152 contains an electrolyte that transfers lithium ions to and from the negative electrode active material. There are no particular limitations on the electrolyte as long as it has lithium ion conductivity, and materials generally 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 152 may be the same as or different from the electrolyte contained in the first active material layer 142 or the electrolyte layer 160 .

[0060] The second active material layer 152 may contain a conductive additive, a binder, etc. These materials are not particularly limited, but may be the same as the materials used for the first active material layer 142 described above.

[0061] In the present embodiment, the second active material layer 152 is formed on both main surfaces of the second current collector layer 151, but this is not limiting, and the second active material layer 152 may be formed on only one main surface of the second current collector layer 151. Furthermore, when the second current collector layer 151 has a three-dimensional porous structure such as a mesh, nonwoven fabric, or foam, the second current collector layer 151 may be provided integrally with the second active material layer 152.

[0062] (electrolyte layer) The electrolyte layer 160 is disposed between the first active material layer 142 and the second active material layer 152. In the direction perpendicular to the stacking direction, the area of ​​the electrolyte layer 160 is larger than the area of ​​the first active material layer 142 in the positive electrode 140. This makes it possible to suppress lithium electrodeposition on the outer periphery of the electrode.

[0063] The electrolyte is not particularly limited as long as it has lithium ion conductivity and insulating properties, and materials generally 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-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 form of the electrolyte material is not particularly limited, and may be, for example, particulate. When the electrolyte layer 160 is a solid electrolyte layer, the electrode stack 120 is made entirely of solids, and the electrode stack 120 can stand on its own inside the can body 110. After the electrode stack 120 is inserted inside the can body 110, the holding member 130 and the like can be placed therein.

[0064] The electrolyte layer 160 may contain an adhesive to impart mechanical strength and flexibility.

[0065] The electrolyte layer 160 may be in the form of a sheet having a porous substrate and a solid electrolyte held in 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. Of these forms, nonwoven fabric is preferred from the viewpoint of handleability, which allows for a greater loading amount of solid electrolyte.

[0066] The porous substrate is preferably made of an insulating material, which can improve the insulation of the electrolyte layer 160. 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.

[0067] The holding member 130 is made of metal-coated hollow beads 1 according to an embodiment described below. That is, the holding member 130 is made of metal-coated hollow beads 1 that have hollow beads made of a thermoplastic resin, a metal layer formed on the outer circumferential surface of the hollow beads, and a fluid contained in the internal space of the hollow beads, and that have a second volume after heating that is larger than a first volume before heating.

[0068] As shown in FIG. 1 , in the can-type battery 100 of this embodiment, it is preferable that a first insulator 171 is disposed between the electrode stack 120 and the holding member 130, and a second insulator 172 is disposed between the can body 110 and the holding member 130. By disposing the first insulator 171 between the electrode stack 120 and the holding member 130, damage to the electrode stack 120 can be suppressed when the electrode stack 120 is housed in the can body 110. By disposing the second insulator 172 between the can body 110 and the holding member 130, it is possible to suppress deterioration of conductivity due to electricity flowing to various locations. Note that either the first insulator 171 or the second insulator 172 may be disposed alone, or both may be disposed.

[0069] The first insulator 171 and the second insulator 172 are preferably films or sheets made of at least one material selected from polyethylene, polypropylene, polyethylene terephthalate, polyamide, polyamideimide, polyvinylidene fluoride, and polytetrafluoroethylene. By disposing the first insulator 171 and the second insulator 172 made of a resin with appropriate hardness and flexibility, the first insulator 171 and the second insulator 172 function as buffer materials and can protect the electrode stack 120. Note that if the resin is too hard, it may lead to damage to the electrode stack 120. Note that the first insulator 171 and the second insulator 172 may be made of the same material or different materials.

[0070] In the can-type battery 100 of this embodiment, the metal-coated hollow beads 1 of the holding member 130 are preferably bonded to the base layer via an adhesive. Examples of adhesives include urethane adhesives, acrylic adhesives, and silicone adhesives. By using an adhesive, the amount of the metal-coated hollow beads fixed to the base layer can be adjusted within a predetermined range.

[0071] Furthermore, in the can-type battery 100 of this embodiment, it is preferable that a first insulator 171 is disposed to cover the electrode surface 120a of the electrode laminate 120. The first insulator 171 covering the electrode surface 120a of the electrode laminate 120 can prevent damage to the electrode laminate 120. Furthermore, by disposing a first insulator 171 that covers the electrode surface 120a of the electrode stack 120 and disposing a second insulator 172 between the can body 110 and the holding member 130, it is possible to improve the insulation between the holding member 130 and the electrode stack 120 and between the can body 110 and the electrode stack 120 and the can body 110. By disposing the first insulator 171 and the second insulator 172, electrical conductivity is improved, resulting in improved battery performance.

[0072] In the can-type battery 100 of this embodiment, the holding member 130 expands upon heating, thereby applying pressure to the electrode stack 120 in the stacking direction. When metal-coated hollow beads 1 are used as the holding member 130, the multiple metal-coated hollow beads 1 deform or move from high-stress concentration areas to low-stress areas during expansion, preventing stress concentration at the contact points between the metal-coated hollow beads 1 and the electrode stack 120, thereby preventing damage to the electrode stack 120. Furthermore, the deformation of the metal-coated hollow beads 1 can mitigate expansion or contraction of the electrode stack 120 during charging and discharging of the can-type battery 100. Specifically, when the electrode stack 120 expands during charging of the can-type battery 100, the surrounding metal-coated hollow beads 1 press down on the electrode stack 120, thereby reducing the expansion rate. Furthermore, the multiple metal-coated hollow beads 1 can accommodate dimensional and geometric tolerances of the electrode stack 120, preventing damage to the electrode stack 120. When a rubber elastic body is used as the holding member 130, the expansion force of the rubber elastic body can absorb variations in the expansion rate of the individual metal-coated hollow beads 1, making it possible to form a holding member 130 containing more uniform metal-coated hollow beads 1, and applying pressure with the uniform holding member 130 further improves the holding force of the electrode stack 120. Furthermore, by covering the electrode surface 120a of the electrode stack 120 with a rubber elastic body before placing the electrode stack 120 inside the can body 110, the electrode surface 120a of the electrode stack 120 does not come into direct contact with the edge or wall surface of the can body 110, and the rubber elastic body and the metal-coated hollow beads 1 act as cushions when an impact is applied, which helps to prevent damage to the electrode stack 120.

[0073] [Manufacturing method of can-type batteries] A method for manufacturing a can-type battery according to an embodiment of the present invention includes the steps of: arranging an electrode stack composed of a positive electrode, a negative electrode, and an electrolyte layer inside a can body (hereinafter referred to as the "first step"); arranging a holding member in the gap between the can body and the electrode stack (hereinafter referred to as the "second step"); and heating and expanding the holding member, pressurizing the electrode stack in the stacking direction with the holding member, and holding the electrode stack within the can body with the holding member (hereinafter referred to as the "third step").

[0074] A method for manufacturing a can-type battery according to an embodiment of the present invention will be described with reference to FIG.

[0075] In the first step, the electrode stack 120 is placed inside the main body 111 of the can body 110. At this time, it is preferable to place an insulating member on the bottom surface 111a inside the main body 111 so that the can body 110 and the electrode stack 120 do not come into direct contact with each other.

[0076] In the second step, a holding member 130 is placed in the gap 113 between the can body 110 and the electrode stack 120. As the holding member 130, the metal-coated hollow beads 1 of the above-described embodiment or the filler member 10 of the above-described embodiment is used.

[0077] In the third step, the holding member 130 is heated and expanded, and the holding member 130 presses the electrode stack 120 in the stacking direction, and the holding member 130 holds the electrode stack 120 within the can body 110. For example, metal-coated hollow beads 1, which will be described later, are used as the holding member 130. The metal-coated hollow beads 1 have a metal layer formed on the outer surface of the hollow beads, so that they shrink less when cooled after heating than hollow beads without a metal layer, and the pressure applied to the laminate by the holding member 130 is less likely to decrease.

[0078] To heat the holding member 130, for example, a heater such as an electric heater is placed so as to be in contact with the outer surface of the can body 110, and the holding member 130 is heated via the can body 110 by the heater.

[0079] The temperature to which the holding member 130 is heated is preferably high and for a short period of time, as long as it does not affect the electrode stack 120. Specifically, when the holding member 130 is heated to 100°C or higher, the holding member 130 expands. As a result, the holding member 130 presses the electrode stack 120 in the stacking direction, and the holding member 130 can hold the electrode stack 120 within the can body 110.

[0080] The manufacturing method for a can-type battery of this embodiment preferably includes at least one of the steps of arranging a first insulator 171 between the electrode stack 120 and the holding member 130 before the first step, and arranging a second insulator 172 between the can body 110 and the holding member 130 before the first step. By arranging the first insulator 171 between the electrode stack 120 and the holding member 130, damage to the electrode stack 120 can be suppressed when the electrode stack 120 is housed in the can body 110. By arranging the second insulator 172 between the can body 110 and the holding member 130, it is possible to suppress deterioration of conductivity due to electricity flowing to various locations.

[0081] The manufacturing method for a can-type battery of this embodiment preferably includes, before the first step, a step of arranging a first insulator 171 that covers the electrode surface 120a of the electrode laminate 120. By arranging the first insulator 171 that covers the electrode surface 120a of the electrode laminate 120 before arranging the electrode laminate 120 inside the can body 110, the electrode laminate 120 does not directly contact the edge or inner wall of the can body 110 when arranging the electrode laminate 120 inside the can body 110, and damage to the electrode laminate 120 can be suppressed. Furthermore, the manufacturing method for a can-type battery of this embodiment includes, before the first step, a step of arranging a second insulator 172 between the can body 110 and the holding member 130. By arranging the electrode laminate 120 inside the can body 110, the electrode laminate 120 does not directly contact the edge or inner wall of the can body 110 when arranging the electrode laminate 120 inside the can body 110, and damage to the electrode laminate 120 can be suppressed.

[0082] According to the manufacturing method of the can-type battery of this embodiment, the holding member 130 expands upon heating, thereby applying pressure to the electrode stack 120 in the stacking direction. When metal-coated hollow beads 1 are used as the holding member 130, the multiple metal-coated hollow beads 1 deform during expansion and move from areas of high stress concentration to areas of low stress, preventing stress from concentrating at the contact points between the metal-coated hollow beads 1 and the electrode stack 120, thereby preventing damage to the electrode stack 120. Furthermore, the deformation of the metal-coated hollow beads 1 can alleviate the expansion or contraction of the electrode stack 120 during battery charge and discharge. Furthermore, the multiple metal-coated hollow beads 1 can accommodate dimensional tolerances and geometric tolerances of the electrode stack 120, preventing damage to the electrode stack 120. When a rubber elastic body is used as the holding member 130, the expansion force of the rubber elastic body can absorb the variations in the expansion rate of the individual metal-coated hollow beads 1, making it possible to form a holding member 130 containing more uniform metal-coated hollow beads 1, and the holding force of the electrode stack 120 is further improved by applying pressure with the uniform holding member 130. Furthermore, by covering the electrode surface 120a of the electrode laminate 120 with a rubber elastic material before placing the electrode laminate 120 inside the can body 110, the electrode surface 120a of the electrode laminate 120 does not come into direct contact with the edge or wall surface of the can body 110, and when an impact is applied, the rubber elastic material and the metal-coated hollow beads 1 act as a cushion, which helps to prevent damage to the electrode laminate 120.

[0083] [Metal-coated hollow beads] FIG. 2 is a cross-sectional view showing a metal-coated hollow bead according to a second embodiment of the present invention.

[0084] 2, the metal-coated hollow beads 1 of this embodiment include hollow beads 2, a metal layer 3, and a fluid 4. The metal layer 3 is formed on the entire outer surface 2a of the hollow beads 2. The fluid 4 is contained in the internal space 2b of the hollow beads 2.

[0085] The hollow beads 2 are made of a thermoplastic resin, such as polyethylene (PE), polypropylene (PP), acrylic resin (methyl methacrylate, PMMA), polyamide (PA), acrylonitrile butadiene styrene (ABS), polyethylene terephthalate (PET), and polyacetal (POM).

[0086] The hollow beads 2 are made of a thermoplastic resin and contain a fluid 4, so they expand when heated. The temperature at which the hollow beads 2 expand when heated is preferably 100°C or higher. When heated to 100°C or higher, the fluid 4 in the internal space 2b of the hollow beads 2 expands, causing the hollow beads 2 to expand. Furthermore, the hollow beads 2 that have expanded when heated maintain their expanded shape even when the temperature is lowered.

[0087] The hollow beads 2 preferably have an average particle size (D50) of 50 μm or less before heating and an average particle size (D50) of more than 50 μm and less than 200 μm after heating. That is, the hollow beads 2 more preferably have a volume expansion rate due to heating of 10% or more and 300% or less. Therefore, the metal-coated hollow beads 1 have a second volume after heating that is larger than the first volume before heating. If the average particle size (D50) of the hollow beads 2 before heating exceeds 50 μm, for example, when multiple metal-coated hollow beads 1 arranged in a gap between two members are heated, the gaps between the metal-coated hollow beads 1 expanded by heating will become larger. As a result, the force with which the expanded metal-coated hollow beads 1 press the two members will become uneven.

[0088] The metal layer 3 contains at least one selected from copper, aluminum, nickel, tin, silver, and gold. The metal layer 3 may be composed of only one of these metals, or two or more of them. By including at least one metal selected from copper, aluminum, nickel, tin, silver, and gold in the metal layer 3, the heat dissipation and thermal conductivity of the metal layer 3 are improved, suppressing heat buildup, and allowing heat to be evenly transferred throughout the metal-coated hollow beads 1 when heated. Furthermore, the rigidity of the metal-coated hollow beads 1 is also increased. For example, when a metal-coated hollow bead 1 placed in a gap between two components is heated, the expanded metal-coated hollow bead 1 presses the two components together, holding one component against the other. Compared to hollow beads without a metal layer, the metal-coated hollow beads 1 have higher rigidity, resulting in increased holding power and pressure.

[0089] The thickness of the metal layer 3 is defined by the following formula (1). (Thickness of metal layer) / (Thickness of outer shell of hollow bead)≦{(Young's modulus of thermoplastic resin layer) / (Young's modulus of metal layer)} 1 / 3 (1)

[0090] By defining the thickness of the metal layer 3 by the above formula (1), the metal layer 3 also stretches as the hollow beads 2 expand upon heating, and the diameter of the hollow beads 2 can be increased without the metal layer 3 peeling off from the hollow beads 2.

[0091] Here, preferred combinations of the material of the hollow beads 2 and the material of the metal layer 3 include, for example, metal layer 3 material / hollow bead 2 material = nickel / polyethylene terephthalate, tin / polypropylene, copper / polyamide, tin / polyethylene, etc. Preferred values ​​for the thickness ratio ((metal layer thickness) / (hollow bead shell thickness)) in these combinations are shown in Table 1. By calculating the thickness of the metal layer 3 using the values ​​in Table 1, the metal layer 3 can be stretched as the hollow beads 2 expand upon heating, thereby increasing the bead diameter while preventing the metal layer 3 from peeling off.

[0092] [Table 1]

[0093] The fluid 4 may be a gas or a liquid. Examples of gases include air, neutral gases such as nitrogen gas, and inert gases such as argon and helium. Of these, nitrogen gas is preferred. If the fluid is nitrogen gas, when the temperature of a battery including the metal-coated hollow beads 1 rises above a predetermined temperature, the metal-coated hollow beads 1 burst, filling the battery with nitrogen and blocking oxygen, thereby delaying the time until ignition and suppressing the spread of fire. Examples of liquids include low-boiling-point solvents with boiling points of approximately 110°C to 170°C, such as ethylene carbonate and propylene carbonate.

[0094] The metal-coated hollow beads 1 preferably contain a material in the internal space 2b of the hollow beads 2 that expands the hollow beads 2 by a phase change. Here, the phase change refers to a thermal change or the like.

[0095] According to the metal-coated hollow beads 1 of this embodiment, for example, when the metal-coated hollow beads 1 placed in the gap between two members are heated, the expanded metal-coated hollow beads 1 pressurize the two members and hold one member against the other. Specifically, as described above, by placing the metal-coated hollow beads 1 in the gap between the can body 110 and the electrode laminate 120 and filling the gap with the metal-coated hollow beads 1, the metal-coated hollow beads 1 act as a cushion for the electrode laminate 120 and can prevent damage to the electrode laminate 120.

[0096] When thermoplastic resin materials such as polypropylene, polystyrene, and polyethylene terephthalate, as well as glass materials, are heated to a temperature where their storage modulus / Young's modulus becomes very small and they exhibit large elongation with low stress. This temperature is called the glass transition point. Resin materials are significantly deformed above the glass transition point, and when the temperature is lowered while still at this deformation, the deformed state of the resin material can be maintained. This shape-retention function is called the shape memory effect. Applying this phenomenon to metal-coated hollow beads 1, below the glass transition point, they undergo normal elastic deformation. However, above the glass transition point, they undergo superelastic deformation (large deformation with low stress), resulting in a large expansion of the metal-coated hollow beads 1. When the temperature is lowered from this state, the expanded diameter decreases slightly due to the decrease in internal pressure. When the temperature is lowered below the glass transition point, the deformation remains at the level just above the glass transition point, and the storage modulus / Young's modulus transitions to a state with a large deformation, and the large deformation is fixed (shape memory effect). Therefore, even when the temperature is lowered, they do not return to their original state before being heated above the glass transition point. Shape memory materials (metals, resins) utilize this property.

[0097] [Filling material] FIG. 3 is a cross-sectional view showing a filling member according to a second embodiment of the present invention.

[0098] 3, a filling member 10 of this embodiment has a rubber elastic body 11 and the metal coated hollow beads 1 of the above-described embodiment. The metal coated hollow beads 1 are contained within the rubber elastic body 11.

[0099] The rubber elastic body 11 is preferably made of urethane rubber or silicone rubber. When the rubber elastic body 11 is made of urethane rubber or silicone rubber, the metal-coated hollow beads 1 can be prevented from being crushed inside the rubber elastic body 11.

[0100] The elastic modulus of the rubber elastic body 11 is preferably lower than that of the metal-coated hollow beads 1. In a normal state (before heating), if the elastic modulus of the rubber elastic body 11 is lower than that of the metal-coated hollow beads 1, the metal-coated hollow beads 1 can be prevented from being crushed within the rubber elastic body 11. In addition, after heating, the metal-coated hollow beads 1 themselves can expand and burst around a predetermined temperature for thermal runaway.

[0101] The thickness of the rubber elastic body 11 is preferably greater than 50 μm. If the thickness of the rubber elastic body 11 is 50 μm or less, the rubber elastic body 11 cannot stand on its own, and uniform pressure cannot be applied when heated due to folds or wrinkles, leading to the possibility of breakage.

[0102] The content of the metal-coated hollow beads 1 in the rubber elastic body 11 is preferably 40% by volume or more and 80% by volume or less. If the content of the metal-coated hollow beads 1 is less than 40% by volume, the expansion force of the rubber elastic body 11 will be overcome and the metal-coated hollow beads 1 will not be able to expand within the rubber elastic body 11. If the content of the metal-coated hollow beads 1 exceeds 80% by volume, the amount of the rubber elastic body 11 will be too small and the filling member will not be able to stand on its own. Furthermore, by adjusting the content of the metal-coated hollow beads 1, the expansion rate of the filling member 10 can be controlled.

[0103] According to the filling member 10 of this embodiment, for example, when the filling member 10 placed in the gap between two members is heated, the expanding filling member 10 pressurizes the two members and holds one member against the other member.

[0104] [Can-type battery] Fig. 4 is a cross-sectional view showing a can-type battery according to a fourth embodiment of the present invention. In Fig. 4, the same components as those shown in Fig. 1 are given the same reference numerals, and the description thereof will be omitted.

[0105] 4, the can-type battery 200 of this embodiment includes a can body 110, an electrode stack 120, and a holding member 130. In the can-type battery 200 of this embodiment, the holding member 130 is made of the filling member 10 of the above-described embodiment.

[0106] According to the can-type battery 200 of this embodiment, the same effects as those of the can-type battery 100 of the first embodiment described above can be obtained.

[0107] 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 variations are possible within the scope of the gist of the present invention as set forth in the claims. [Example]

[0108] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to the following examples.

[0109] [Example] A microbubble generator was placed in the water to generate nitrogen microbubbles. Styrene monomer and a polymerization initiator were added to the stirred water containing the nitrogen microbubbles to produce nitrogen-containing hollow beads. Polymerization of the styrene monomer began at the interface between the water and nitrogen, resulting in nitrogen-containing hollow beads with a particle size of 50 μm. The surfaces of the obtained nitrogen-containing hollow beads were plated with tin by a plating method, to obtain metal-coated hollow beads in which a tin-plated layer was formed on the surfaces of the nitrogen-containing hollow beads. The obtained metal-coated hollow beads and an electrode laminate were placed in a can. The proportion of the metal-coated hollow beads to the total volume (100% by volume) of the gap between the can and the electrode laminate was 62% by volume. The metal-coated hollow beads in the container were heated and the expansion coefficient of the metal-coated hollow beads was measured while changing the temperature from room temperature (25° C.) to 130° C. The results are shown in FIG. The results shown in Figure 5 indicate that the expansion rate of the metal-coated hollow beads increases at temperatures above 100°C, expanding by 5% or more compared to their state before heating. [Explanation of symbols]

[0110] 1 Metal-coated hollow beads 2 hollow beads 3 metal layer 4 fluid 10 Filler material 11 Rubber elastic body 100 can type batteries 110 Can body 111 Main Unit 112 Lid 113 void 120 Electrode laminate 130 Retaining member 140 Positive electrode 150 negative electrode 160 Electrolyte layer 171 First Insulator 172 Second Insulator

Claims

1. an electrode stack housed in a can body and composed of a positive electrode, a negative electrode, and an electrolyte layer; a holding member disposed in a gap between the can body and the electrode stack, and holding the electrode stack within the can body; Equipped with The retaining member is a filling member having metal-coated hollow beads or a rubber elastic body, and the metal-coated hollow beads contained within the rubber elastic body, the holding member having hollow beads made of a thermoplastic resin, a metal layer formed on the outer surface of the hollow beads, and a fluid contained in the internal space of the hollow beads, the second volume after heating being larger than the first volume before heating, and the increase in volume pressurizing the stack in the stacking direction.

2. The can-type battery according to claim 1 , wherein an insulator is disposed at least one of between the electrode stack and the holding member and between the can body and the holding member.

3. 3. The can-type battery according to claim 2, wherein the insulator is a film or sheet made of at least one material selected from the group consisting of polyethylene, polypropylene, polyethylene terephthalate, polyamide, polyamideimide, polyvinylidene fluoride, and polytetrafluoroethylene.

4. 2. The can-type battery according to claim 1, wherein the electrolyte layer is a solid electrolyte layer.

5. 2. The can-type battery according to claim 1, wherein the fluid is nitrogen gas.

6. 2. The can-type battery according to claim 1, wherein the hollow beads have a temperature at which they expand when heated of 100° C. or higher.

7. 2. The can-type battery according to claim 1, wherein the metal layer contains at least one selected from the group consisting of copper, aluminum, nickel, tin, silver, and gold.

8. 8. The can-type battery according to claim 7, wherein the thickness of the metal layer is defined by the following formula (1): (Thickness of metal layer) / (Thickness of outer shell of hollow bead)≦{(Young's modulus of thermoplastic resin layer) / (Young's modulus of metal layer)} １／３ (1)

9. 2. The can-type battery according to claim 1, wherein the hollow beads have an average particle size (D50) of 50 μm or less before heating and an average particle size (D50) of more than 50 μm and 200 μm or less after heating.

10. 2. The can-type battery according to claim 1, wherein the rubber elastic body is made of urethane rubber or silicone rubber.

11. 11. The can-type battery according to claim 10, wherein the elastic modulus of the rubber elastic body is lower than the elastic modulus of the metal-coated hollow beads.

12. 2. The can-type battery according to claim 1, wherein the thickness of the rubber elastic body is 50 [mu]m or more.

13. 2. The can-type battery according to claim 1, wherein the content of the metal-coated hollow beads in the filling member is 40% by volume or more and 80% by volume or less.

14. a step of disposing an electrode stack including a positive electrode, a negative electrode, and an electrolyte layer inside the can body; disposing a retaining member in a gap between the can body and the electrode stack; a step of heating the holding member to expand it, pressurizing the electrode stack in a stacking direction with the holding member, and holding the electrode stack in the can body with the holding member; and The method for manufacturing a can-type battery, wherein the retaining member is a filling member having metal-coated hollow beads or a rubber elastic body and the metal-coated hollow beads contained within the rubber elastic body, the filling member having hollow beads made of a thermoplastic resin, a metal layer formed on the outer surface of the hollow beads, and a fluid contained in the internal space of the hollow beads, the second volume after heating being larger than the first volume before heating, and the increase in volume pressurizing the stack in the stacking direction.

15. 15. The method for manufacturing a can-type battery according to claim 14, further comprising, before the step of arranging the electrode stack, a step of arranging an insulator at least one between the electrode stack and the holding member and between the can body and the holding member.

16. The method for manufacturing a can-type battery according to claim 14 , further comprising, before the step of arranging the electrode stack, a step of arranging an insulator that covers the electrode surfaces of the electrode stack.

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