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

Abstract

Provided is a can-type battery having a mechanism for absorbing dimensional tolerances and geometric tolerances of an electrode laminate when the electrode laminate is pressurized, and having a mechanism for serving as a buffer for preventing breakage of the electrode laminate, wherein the holding force of the electrode laminate with respect to a single cell is large and the can-type battery is provided with a mechanism for absorbing dimensional tolerances and geometric tolerances of the electrode laminate when the electrode laminate is pressurized. A can-type battery is provided with a can body, an electrode laminate housed in the can body and comprising a positive electrode, a negative electrode, and an electrolyte layer, and a holding member disposed in a gap between the can body and the electrode laminate and holding the electrode laminate in the can body, the holding member being a metal-covered hollow bead or a filling member. The metal-covered hollow bead has a hollow bead comprising a thermoplastic resin, a metal layer formed on the outer peripheral surface of the hollow bead, and a fluid enclosed in the internal space of the hollow bead, and the second volume after heating is larger than the first volume before heating. The filling member has a rubber elastic body and a metal-covered hollow bead contained in the rubber elastic body.

Description

[0001] Cross-references between related applications

[0002] This application claims priority based on Japanese Patent Application No. 2024-045260 filed on March 21, 2024, the contents of which are incorporated herein by reference. Technical Field

[0003] The present invention relates to a can-type battery and a method for manufacturing the can-type battery. Background Art

[0004] In sealed batteries, an electrode stack consisting of a positive electrode, a negative electrode, and an electrolyte layer is housed within a cylindrical unit cell. In such batteries, a pressurizing spacer, which pressurizes the electrode stack in the stacking direction, is housed within the unit cell. The pressurizing spacer deforms to increase the volume occupied within the unit cell, thereby retaining the electrode stack within the unit cell (see, for example, Japanese Patent Application Laid-Open No. 8-83624). Summary of the Invention

[0005] Since the pressurizing spacer has no mechanism for absorbing the dimensional tolerance and geometric tolerance of the electrode stack, there is a problem in that the electrode stack may be damaged.

[0006] The present invention provides a can-type battery that has a strong electrode stack retaining force relative to the single cells, a mechanism for absorbing dimensional and geometric tolerances of the electrode stack when pressurized, and a mechanism for preventing damage to the electrode stack. Furthermore, the present invention contributes to stabilizing battery performance, improving quality control during the manufacturing process, and increasing energy efficiency.

[0007] The solution of the present invention provides the following structure.

[0008] [1] A can-type battery, wherein:

[0009] The can type battery comprises:

[0010] Tank;

[0011] an electrode stack housed in a can and consisting of a positive electrode, a negative electrode, and an electrolyte layer; and

[0012] a holding member disposed in a gap between the can and the electrode stack and holding the electrode stack in the can,

[0013] The retaining member is a metal-covered hollow bead or a filling member, the metal-covered hollow bead includes a hollow bead made of a thermoplastic resin, a metal layer formed on the outer peripheral surface of the hollow bead, and a fluid enclosed in the internal space of the hollow bead, and the second volume after heating is larger than the first volume before heating. The filling member includes a rubber elastic body and the metal-covered hollow bead contained in the rubber elastic body.

[0014] Under the action of heating, the holding member expands so that the electrode stack can be pressurized along the stacking direction. In the case of using metal-covered hollow beads as a holding member, when expanding, multiple metal-covered hollow beads are deformed and moved from a place with higher stress concentration to a place with lower stress concentration, so that stress will not be concentrated on the contact portion where the metal-covered hollow beads contact the electrode stack, thereby suppressing the damage of the electrode stack. In addition, the deformation of the metal-covered hollow beads can be used to alleviate the expansion or contraction of the electrode stack during the charge and discharge of the battery. Specifically, when the electrode stack expands during the charging of the battery, the metal-covered hollow beads located around it press against the electrode stack so as to reduce the expansion rate. In addition, multiple metal-covered hollow beads can be used to absorb the dimensional tolerance and geometric tolerance of the electrode stack, thereby suppressing the damage of the electrode stack. In a structure using a rubber elastic body as a retaining member, the expansion force of the rubber elastic body can be used to absorb the uneven expansion rate of each metal-covered hollow bead, which can form a more uniform filling member containing metal-covered hollow beads. By using a uniform filling member to apply pressure, the holding force of the electrode stack is further improved. In addition, by covering the electrode surface of the electrode stack with a rubber elastic body before the electrode stack is arranged inside the can body, the electrode surface of the electrode stack will not directly contact the edge or wall of the can body. When an impact is applied, the rubber elastic body and the metal-covered hollow beads act as buffers, thereby suppressing the damage of the electrode stack. Under the action of heat, the hollow beads expand. Therefore, for example, when the metal-covered hollow beads arranged in the gap between two components are heated, the expanded metal-covered hollow beads pressurize the two components, which can hold the component on one side relative to the component on the other side.

[0015] Since the inner space of the hollow beads contains a material that expands the hollow beads due to phase change, the hollow beads easily expand when heated.

[0016] The filling member comprises a rubber elastic body and metal-coated hollow beads contained within the rubber elastic body, allowing it to self-erect. Furthermore, since the metal-coated hollow beads are contained within the rubber elastic body, variations in the expansion rates of the individual metal-coated hollow beads can be absorbed by the rubber elastic body, resulting in a more uniform filling member.

[0017] [2] The can-type battery according to [1], wherein:

[0018] An insulator is disposed between at least one of the electrode stack and the holding member and between the can and the holding member.

[0019] By disposing an insulator between at least one of the electrode stack and the holding member and 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.

[0020] [3] The can-type battery according to [2], wherein:

[0021] The insulator is a film or sheet made of at least one selected from polyethylene, polypropylene, polyethylene terephthalate, polyamide, polyamideimide, polyvinylidene fluoride, and polytetrafluoroethylene.

[0022] By using an insulator made of a resin having appropriate hardness and flexibility, the insulator functions as a buffer material and can protect the electrode stack. However, if the hardness of the resin is too high, the electrode stack may be damaged.

[0023] [4] The can-type battery according to [1], wherein:

[0024] The electrolyte layer is a solid electrolyte layer.

[0025] When the electrolyte layer is a solid electrolyte layer, the electrode stack is entirely made of solid and can stand on its own inside the can. Metal-coated hollow beads can be arranged after the electrode stack is inserted into the can.

[0026] [5] The can-type battery according to [1], wherein:

[0027] The fluid is nitrogen.

[0028] When the fluid is nitrogen, if the temperature of a battery equipped with metal-coated hollow beads rises above a specified temperature, the metal-coated hollow beads rupture, filling the battery with nitrogen and blocking oxygen. This delays the onset of fire and suppresses the spread of fire. Furthermore, when metal-coated hollow beads are used in can-type batteries, there is a slight margin of space between the can and the electrode stack. If the can-type battery experiences thermal runaway and a portion of the stack expands, stress concentration in the expanded area is avoided and the hollow beads migrate to other locations, thus mitigating some thermal runaway and improving safety.

[0029] [6] The can-type battery according to [1], wherein:

[0030] The temperature at which the hollow beads expand under heating is above 100°C.

[0031] When heated to 100° C. or higher, the fluid in the inner space of the hollow beads expands, causing the hollow beads to expand.

[0032] [7] The can-type battery according to [1], wherein:

[0033] The metal layer includes at least one selected from copper, aluminum, nickel, tin, silver, and gold.

[0034] The metal layer, which includes at least one selected from copper, aluminum, nickel, tin, silver, and gold, improves the metal layer's heat dissipation and thermal conductivity, suppressing temperature increases. Furthermore, when the metal-coated hollow beads are heated, heat is evenly transferred throughout the entirety of the beads. Furthermore, the rigidity of the metal-coated hollow beads is increased. Therefore, for example, when a metal-coated hollow bead is heated in a gap between two components, the expanded metal-coated hollow bead pressurizes the two components, holding one component relative to the other.

[0035] [8] The can-type battery according to [1], wherein:

[0036] The thickness of the metal layer is defined by the following formula (1).

[0037] (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)

[0038] By defining the thickness of the metal layer using the above formula (1), the hollow beads expand under heating, and the metal layer also extends, so that the diameter of the beads can be increased without the metal layer being separated from the hollow beads.

[0039] [9] The can-type battery according to [1], wherein:

[0040] The average particle size (D50) of the hollow beads before heating is 50 μm or less, and the average particle size (D50) of the hollow beads after heating is more than 50 μm and 200 μm or less.

[0041] If the average particle size (D50) of the hollow beads before heating exceeds 50 μm, for example, when multiple metal-coated hollow beads are placed in a gap between two components and heated, the gaps between the metal-coated hollow beads expand due to the heat. Consequently, the force exerted by the expanded metal-coated hollow beads on the two components becomes uneven.

[0042]

[10] The can-type battery according to [1], wherein:

[0043] The rubber elastic body is made of urethane rubber or silicone rubber.

[0044] The rubber elastic body is composed of urethane rubber or silicone rubber, and thus it is possible to suppress the metal-coated hollow beads from being crushed within the rubber elastic body.

[0045]

[11] The can-type battery according to [1], wherein:

[0046] The elastic modulus of the rubber elastic body is lower than the elastic modulus of the metal-coated hollow beads.

[0047] The elastic modulus of the rubber elastic body is lower than that of the metal-coated hollow beads, and thus it is possible to suppress the metal-coated hollow beads from being crushed within the rubber elastic body.

[0048]

[12] The can-type battery according to

[10] or

[11] , wherein:

[0049] The rubber elastic body has a thickness of 50 μm or more.

[0050] If the thickness of the rubber elastic body is less than 50 μm, the rubber elastic body cannot stand up on its own, causing bends and wrinkles in the rubber elastic body. The bends and wrinkles make the rubber elastic body uneven in thickness, making it impossible to uniformly pressurize the laminate when heated, resulting in damage to the laminate.

[0051]

[13] The can-type battery according to [1], wherein:

[0052] The content of the metal-coated hollow beads in the filling member is 40% by volume or more and 80% by volume or less.

[0053] If the metal-coated hollow beads contain less than 40% by volume in the filling member, they cannot follow the expansion force of the rubber elastic body and cannot expand within the rubber elastic body. If the metal-coated hollow beads contain more than 80% by volume in the filling member, the amount of rubber elastic body decreases, and the filling member cannot stand upright on its own. Furthermore, by adjusting the metal-coated hollow beads content, the expansion rate of the filling member can be controlled.

[0054]

[14] A method for manufacturing a can-type battery, wherein:

[0055] The manufacturing method of the can type battery comprises:

[0056] The process of disposing an electrode stack composed of a positive electrode, a negative electrode, and an electrolyte layer inside the can;

[0057] a step of disposing a holding member in a gap between the can and the electrode stack; and

[0058] a step of heating the holding member to expand the holding member, pressurizing the electrode stack in a stacking direction by the holding member, and holding the electrode stack in the can body by the holding member;

[0059] The retaining member is a metal-covered hollow bead or a filling member, the metal-covered hollow bead includes a hollow bead made of a thermoplastic resin, a metal layer formed on the outer peripheral surface of the hollow bead, and a fluid enclosed in the internal space of the hollow bead, and the second volume after heating is larger than the first volume before heating, and the metal-covered hollow bead pressurizes the stack in the stacking direction by the increase in volume, and the filling member includes a rubber elastic body and the metal-covered hollow bead contained in the rubber elastic body.

[0060] Under the action of heating, the metal covered hollow beads expand so that the electrode stack can be pressurized along the stacking direction. When expanded, multiple metal covered hollow beads are deformed and moved from a place with higher stress concentration to a place with lower stress concentration, so that stress is not concentrated on the contact portion where the metal covered hollow beads contact the electrode stack, and therefore the electrode stack can be damaged. In addition, the deformation of the metal covered hollow beads can be utilized to alleviate the expansion or contraction of the electrode stack during the charge and discharge of the battery. Moreover, multiple metal covered hollow beads can be utilized to absorb the dimensional tolerance and geometric tolerance of the electrode stack, and therefore the electrode stack can be damaged.

[0061]

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

[14] , wherein:

[0062] The method for manufacturing a can-type battery includes, before the step of arranging the electrode stack, a step of arranging an insulator between at least one of the electrode stack and the holding member and between the can body and the holding member.

[0063] By arranging an insulator between at least one of the electrode stack and the holding member and between the can and the holding member before arranging the electrode stack, damage to the electrode stack can be suppressed when the electrode stack is arranged inside the can.

[0064]

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

[14] , wherein:

[0065] The method for manufacturing a can-type battery includes, before the step of arranging the electrode stack, a step of arranging an insulator covering an electrode surface of the electrode stack.

[0066] By arranging the insulator covering the electrode surface of the electrode stack before arranging the electrode stack, it is possible to suppress damage to the electrode stack when the electrode stack is arranged inside the can.

[0067] According to the present invention, a can-type battery can be provided that has a large holding force of the electrode stack relative to the single cell, has a mechanism for absorbing dimensional tolerances and geometric tolerances of the electrode stack when pressurized, and has a mechanism for serving as a buffer to prevent damage to the electrode stack. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] Figure 1 It is a cross-sectional view showing a can-type battery according to the first embodiment of the present invention.

[0069] Figure 2 It is a cross-sectional view showing metal-coated hollow beads according to a second embodiment of the present invention.

[0070] Figure 3 It is a cross-sectional view showing a filling member according to a third embodiment of the present invention.

[0071] Figure 4 It is a cross-sectional view showing a can-type battery according to a fourth embodiment of the present invention.

[0072] Figure 5 This is a graph showing the relationship between the heating temperature of the metal-coated hollow beads and the expansion coefficient of the metal-coated hollow beads in Examples. DETAILED DESCRIPTION

[0073] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0074] [Can-type battery]

[0075] Figure 1 This is a cross-sectional view of a can-type battery according to the first embodiment of the present invention. It should be noted that the drawings used in the following description may show enlarged portions of the components for ease of understanding, and the dimensional ratios of the components are not limited to those shown.

[0076] like Figure 1 As shown, the can-type battery 100 of this embodiment includes a can 110, an electrode stack 120, and a retaining member 130. The electrode stack 120 is housed in the can 110. The retaining member 130 is disposed in a gap 113 between the can 110 and the electrode stack 120, and retains the electrode stack 120 in the can 110.

[0077] The can 110 is a housing that houses the electrode stack 120 and the holding member 130. The can 110 includes a cylindrical body 111 having a bottom surface 111a and a lid 112 that closes the opening of the body 111.

[0078] The electrode stack 120 is composed of a positive electrode 140 , a negative electrode 150 , and an electrolyte layer 160 .

[0079] The positive electrodes 140 and the negative electrodes 150 are alternately stacked with electrolyte layers 160 interposed therebetween. The can-type battery 100 is charged and discharged by transfer of lithium ions between the positive electrodes 140 and the negative electrodes 150 via the electrolyte layers 160.

[0080] (positive electrode)

[0081] 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 includes the first current collector layer 141 and the first active material layer 142 formed on both main surfaces of the first current collector layer 141 .

[0082] The first current collector layer 141 is preferably made of at least one substance having high electrical conductivity.

[0083] Examples of highly conductive materials include metals or alloys containing at least one of the following metal elements: silver (Ag), palladium (Pd), gold (Au), platinum (Pt), aluminum (Al), chromium (Cr), and nickel (Ni), or non-metallic materials such as carbon (C). Considering manufacturing costs in addition to high conductivity, aluminum, nickel, or stainless steel are preferred. Furthermore, aluminum is less likely to react with the positive electrode active material and electrolyte. Therefore, using aluminum in the first current collector layer 141 can reduce the internal resistance of the battery.

[0084] Examples of the shape of the first current collector layer 141 include foil, plate, mesh, nonwoven fabric, and foam. Furthermore, to improve adhesion to the first active material layer 142, the surface of the first current collector layer 141 may be provided with carbon or roughened.

[0085] The first active material layer 142 includes a positive electrode active material that accepts electrons from lithium ions. As a positive electrode active material, there is no particular limitation as long as it is a material that can reversibly release and absorb lithium ions and can transport electrons. A known positive electrode active material that can be applied to 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 zO2, x+y+z=1), composite oxides such as olivine-type lithium phosphorus oxide (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 can be composed of one of the above materials alone or of two or more.

[0086] The first active material layer 142 includes an electrolyte that transfers lithium ions to and from the positive electrode active material. As an electrolyte, there is no particular limitation as long as it is an electrolyte with lithium ion conductivity, and materials commonly used in lithium ion batteries can be used. As electrolytes, for example, sulfide solid electrolyte materials, oxide solid electrolyte materials, halide solid electrolytes, inorganic solid electrolytes containing lithium salts, solid electrolytes of polymer systems such as polyethylene oxide, and gel-based solid electrolytes containing lithium salts and lithium ion conductive ionic liquids can be cited. Among them, sulfide solid electrolyte materials are preferred from the perspective of high lithium ion conductivity, structural formability based on compression, and good interface bonding.

[0087] The electrolyte may be composed of one of the above materials alone or two or more. 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 and the electrolyte layer 160 , or may be a different material.

[0088] To improve the conductivity of the positive electrode 140, the first active material layer 142 may also contain a conductive additive. Any conductive additive commonly used in lithium-ion batteries can be used. Examples include carbon blacks such as acetylene black and Ketjen Black; carbon fibers; vapor-grown carbon fibers; graphite powder; and carbon nanotubes. The conductive additive may be composed of one of the above materials alone or a combination of two or more.

[0089] Furthermore, the first active material layer 142 may include a binder that has a function of binding the positive electrode active materials to each other and to the first current collector layer 141 .

[0090] In this embodiment, the first active material layer 142 is formed on both main surfaces of the first current collector layer 141. However, this is not limiting. The first active material layer 142 may also be formed on only one main surface of the first current collector layer 141. Furthermore, if the positive electrode 140 is a single-sided coated electrode, a stacked positive electrode formed by stacking two positive electrodes with their current collector surfaces facing each other may be used as a double-sided coated electrode. Furthermore, if the first current collector layer 141 has a three-dimensional porous structure such as a mesh, non-woven fabric, or foam, the first current collector layer 141 may be integrally provided with the first active material layer 142.

[0091] The first current collector layer 141 is gathered at one end portion in the width direction of the can-type battery 100 .

[0092] Since the first active material layer 142 is in contact with the electrolyte layer 160 , the first active material layer 142 may contain the sulfide contained in the electrolyte layer 160 .

[0093] (negative electrode)

[0094] The negative electrode 150 is formed by laminating 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 includes the second current collector layer 151 and the second active material layer 152 formed on both main surfaces of the second current collector layer 151 and containing a negative electrode active material and an electrolyte.

[0095] 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 also contain a substance other than copper with high conductivity. Examples of substances other than copper with 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-metallic carbon (C). When considering manufacturing costs in addition to high conductivity, nickel or stainless steel are preferred as substances 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 in the second current collector layer 151 can reduce the manufacturing cost of the battery.

[0096] Examples of the shape of the second current collector layer 151 include foil, plate, mesh, nonwoven fabric, and foam. Furthermore, to improve adhesion to the second active material layer 152, the surface of the second current collector layer 151 may be provided with carbon or roughened.

[0097] The second active material layer 152 includes a negative electrode active material that accepts electrons from lithium ions. As a negative electrode active material, there is no particular limitation as long as it is a material that can reversibly release and absorb lithium ions and can transport electrons. A known negative electrode active material that can be applied to the negative electrode of a lithium ion battery can be used. For example, carbonaceous materials such as natural graphite, artificial graphite, resin carbon, carbon fiber, activated carbon, hard carbon, and soft carbon; alloy materials based on tin, tin alloys, silicon, silicon alloys, gallium, gallium alloys, indium, indium alloys, aluminum, and aluminum alloys; conductive polymers such as polyphenylene, polyacetylene, and polypyrrole; metallic lithium; lithium-titanium composite oxides (such as Li4Ti5O 12 ) etc. These negative electrode active materials may be composed of one of the above materials alone, or may be composed of two or more.

[0098] The second active material layer 152 includes an electrolyte that transfers lithium ions to and from the negative electrode active material. As an electrolyte, there is no particular limitation as long as it is an electrolyte with lithium ion conductivity, and materials commonly used in lithium ion batteries can be used. Examples of electrolytes include sulfide solid electrolyte materials, oxide solid electrolyte materials, halide solid electrolytes, inorganic solid electrolytes containing lithium salts, solid electrolytes of polymer systems such as polyethylene oxide, and gel-based solid electrolytes containing lithium salts and lithium ion conductive ionic liquids. The electrolyte can be composed of one of the above materials alone, or it can be composed of two or more.

[0099] The electrolyte included in the second active material layer 152 may be the same as or different from the electrolyte included in the first active material layer 142 and the electrolyte layer 160 .

[0100] The second active material layer 152 may also contain a conductive additive, a binder, etc. These materials are not particularly limited, but for example, the same materials as those used for the first active material layer 142 described above can be used.

[0101] In this embodiment, the second active material layer 152 is formed on both main surfaces of the second current collector layer 151. However, the present invention is not limited thereto 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, non-woven fabric, or foam, the second current collector layer 151 may be integrally provided with the second active material layer 152.

[0102] (Electrolyte layer)

[0103] Electrolyte layer 160 is disposed between first active material layer 142 and second active material layer 152. Furthermore, in a direction perpendicular to the stacking direction, the area of ​​electrolyte layer 160 is larger than the area of ​​first active material layer 142 in positive electrode 140. This prevents lithium crystallization at the periphery of the electrodes.

[0104] As electrolyte, as long as it is an electrolyte with lithium ion conductivity and insulation, there is no particular limitation, and materials commonly used in lithium ion batteries can be used. For example, sulfide solid electrolyte materials, oxide solid electrolyte materials, halide solid electrolytes, inorganic solid electrolytes such as lithium salts, solid electrolytes of polymer systems such as polyethylene oxide, and gel electrolytes containing lithium salts and lithium ion conductive ionic liquids can be cited. Among them, from the viewpoint of high lithium ion conductivity and good structural formability and interface bonding based on compression, sulfide solid electrolyte materials are preferably used.

[0105] The electrolyte material is not particularly limited in form, but can be in a particulate form, for example. When the electrolyte layer 160 is a solid electrolyte layer, the electrode stack 120 is entirely solid, and the electrode stack 120 can stand upright within the can 110. After the electrode stack 120 is inserted into the can 110, the retaining member 130 can be positioned.

[0106] The electrolyte layer 160 may also contain a binder for imparting mechanical strength and flexibility.

[0107] The electrolyte layer 160 may also be in the form of a sheet having a porous substrate and a solid electrolyte retained on the porous substrate. The form of the porous substrate is not particularly limited, but examples thereof include woven fabrics, non-woven fabrics, meshes, porous membranes, expansion sheets, punched sheets, and the like. Among these forms, non-woven fabrics are preferred from the perspective of increased handling of the solid electrolyte filling amount.

[0108] The porous substrate is preferably made of an insulating material. This improves the insulation properties of 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 sulfide, polyetheretherketone, cellulose, and acrylic resin; natural fibers such as hemp, wood pulp, and cotton linter; and glass.

[0109] The retaining member 130 is composed of the metal-coated hollow beads 1 of the embodiment described below. Specifically, the retaining member 130 is composed of the metal-coated hollow beads 1, which have a hollow bead made of a thermoplastic resin, a metal layer formed on the outer peripheral surface of the hollow bead, and a fluid enclosed in the interior space of the hollow bead, wherein the second volume after heating is larger than the first volume before heating.

[0110] like Figure 1 As shown, in the can-type battery 100 of this embodiment, a first insulator 171 is preferably disposed between the electrode stack 120 and the retaining member 130, and a second insulator 172 is preferably disposed between the can 110 and the retaining member 130. The placement of the first insulator 171 between the electrode stack 120 and the retaining member 130 prevents damage to the electrode stack 120 when housed in the can 110. The placement of the second insulator 172 between the can 110 and the retaining member 130 prevents the flow of electricity to various locations, which could degrade conductivity. It should be noted that either or both the first insulator 171 and the second insulator 172 may be disposed.

[0111] The first insulator 171 and the second insulator 172 are preferably a film or sheet made of at least one selected from polyethylene, polypropylene, polyethylene terephthalate, polyamide, polyamide-imide, polyvinylidene fluoride, and polytetrafluoroethylene. By configuring the first insulator 171 and the second insulator 172 to be made of a resin having appropriate hardness and flexibility, the first insulator 171 and the second insulator 172 function as a buffer material to protect the electrode stack 120. It should be noted that when the hardness of the resin is too high, it will cause damage to the electrode stack 120. It should be noted that the material of the first insulator 171 and the material of the second insulator 172 can be the same or different.

[0112] In the can-type battery 100 of this embodiment, the metal-coated hollow beads 1 of the retaining member 130 are preferably bonded to the substrate layer via an adhesive. Examples of adhesives include urethane adhesives, acrylic adhesives, and silicone adhesives. The use of an adhesive allows the amount of metal-coated hollow beads fixed to the substrate layer to be adjusted within a predetermined range.

[0113] In the can-type battery 100 of this embodiment, it is preferable to provide a first insulator 171 covering the electrode surface 120a of the electrode stack 120. Covering the electrode surface 120a of the electrode stack 120 with the first insulator 171 can prevent damage to the electrode stack 120. Furthermore, providing the first insulator 171 covering the electrode surface 120a of the electrode stack 120 and providing the second insulator 172 between the can 110 and the retaining member 130 improves insulation between the retaining member 130 and the electrode stack 120 and the can 110. The provision of the first insulator 171 and the second insulator 172 enhances electrical conductivity and battery performance.

[0114] According to the can-type battery 100 of this embodiment, when heated, the retaining member 130 expands, thereby pressurizing the electrode stack 120 in the stacking direction. When metal-coated hollow beads 1 are used as the retaining member 130, during expansion, the multiple metal-coated hollow beads 1 deform and shift stress concentration from areas of higher stress concentration to areas of lower stress concentration. This prevents stress from concentrating on the contact areas 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 the expansion and 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 against the electrode stack 120, thereby reducing the rate of expansion. Furthermore, the multiple metal-coated hollow beads 1 can absorb dimensional and geometric tolerances of the electrode stack 120, thereby preventing damage to the electrode stack 120. In a configuration using a rubber elastic body as the retaining member 130, the expansion force of the rubber elastic body can absorb variations in the expansion rate of each metal-coated hollow bead 1, resulting in a more uniform retaining member 130 containing the metal-coated hollow beads 1. The uniform pressure applied by the retaining member 130 further enhances the retaining force of the electrode stack 120. Furthermore, by covering the electrode surface 120a of the electrode stack 120 with the rubber elastic body before placing the electrode stack 120 inside the can 110, the electrode surface 120a of the electrode stack 120 is prevented from directly contacting the edge or wall of the can 110. When an impact is applied, the rubber elastic body and the metal-coated hollow beads 1 act as buffers, thereby preventing damage to the electrode stack 120.

[0115] [Can-type battery manufacturing method]

[0116] The method for manufacturing a can-type battery according to an embodiment of the present invention includes a step of arranging an electrode stack composed of a positive electrode, a negative electrode, and an electrolyte layer inside a can (hereinafter referred to as the "first step"), a step of arranging a retaining member in a gap between the can and the electrode stack (hereinafter referred to as the "second step"), and a step of heating the retaining member to expand the retaining member, pressurizing the electrode stack in the stacking direction using the retaining member, and retaining the electrode stack inside the can using the retaining member (hereinafter referred to as the "third step").

[0117] Reference Figure 1 A method for manufacturing a can-type battery according to an embodiment of the present invention will be described.

[0118] In the first step, the electrode stack 120 is placed inside the main body 111 of the can 110 . In order to prevent the can 110 and the electrode stack 120 from directly contacting each other, an insulating member is preferably placed on the bottom surface 111 a of the main body 111 .

[0119] In the second step, the holding member 130 is disposed in the gap 113 between the can 110 and the electrode stack 120. As the holding member 130, the metal-coated hollow beads 1 of the above-described embodiment or the filling member 10 of the above-described embodiment can be used.

[0120] In the third step, the holding member 130 is heated to expand the holding member 130 , and the electrode stack 120 is pressurized in the stacking direction by the holding member 130 . The electrode stack 120 is then held in the can 110 by the holding member 130 .

[0121] As the holding member 130, for example, the metal-coated hollow beads 1 described below are used. The metal-coated hollow beads 1 have a metal layer formed on the outer peripheral surface of the hollow beads, so they shrink less when cooled after heating than when they do not have a metal layer, making it difficult for the stacking pressure of the holding member 130 to decrease.

[0122] In order to heat the holding member 130 , for example, a heater such as an electric heater is provided 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.

[0123] The temperature of the holding member 130 is preferably high enough for a short time to not affect the electrode stack 120. Specifically, when the holding member 130 is heated to 100°C or higher, it expands. As a result, the holding member 130 presses the electrode stack 120 in the stacking direction, allowing the holding member 130 to hold the electrode stack 120 within the can 110.

[0124] The can-type battery manufacturing method of this embodiment preferably includes at least one of the steps of placing a first insulator 171 between the electrode stack 120 and the retaining member 130 before the first step, and placing a second insulator 172 between the can 110 and the retaining member 130 before the first step. Placing the first insulator 171 between the electrode stack 120 and the retaining member 130 can prevent damage to the electrode stack 120 when it is housed in the can 110. Placing the second insulator 172 between the can 110 and the retaining member 130 can prevent electricity from flowing to various locations and causing deterioration in conductivity.

[0125] The can-type battery manufacturing method of this embodiment preferably includes a step of disposing a first insulator 171 covering the electrode surface 120a of the electrode stack 120 before the first step. Disposing the first insulator 171 covering the electrode surface 120a of the electrode stack 120 before the electrode stack 120 is placed inside the can 110 prevents the electrode stack 120 from directly contacting the edge or inner wall of the can 110 when the electrode stack 120 is placed inside the can 110, thereby preventing damage to the electrode stack 120. Furthermore, the can-type battery manufacturing method of this embodiment includes a step of disposing a second insulator 172 between the can 110 and the retaining member 130 before the first step. This prevents the electrode stack 120 from directly contacting the edge or inner wall of the can 110 when the electrode stack 120 is placed inside the can 110, thereby preventing damage to the electrode stack 120.

[0126] According to the manufacturing method of the can-type battery of this embodiment, under the action of heat, the retaining member 130 expands, thereby being able to pressurize the electrode stack 120 in the stacking direction. When metal-coated hollow beads 1 are used as the retaining member 130, during expansion, the multiple metal-coated hollow beads 1 deform and move from areas with higher stress concentration to areas with lower stress concentration, so that stress is not concentrated on the contact area between the metal-coated hollow beads 1 and the electrode stack 120, thereby suppressing damage to the electrode stack 120. In addition, the deformation of the metal-coated hollow beads 1 can be used to alleviate the expansion or contraction of the electrode stack 120 during the charging and discharging of the battery. Furthermore, the multiple metal-coated hollow beads 1 can be used to absorb the dimensional tolerance and geometric tolerance of the electrode stack 120, thereby suppressing damage to the electrode stack 120.

[0127] When a rubber elastomer is used as the retaining member 130, the expansion force of the rubber elastomer can be utilized to absorb the differences in the expansion rates of the individual metal-covered hollow beads 1, thereby forming a more uniform retaining member 130 containing the metal-covered hollow beads 1. By applying pressure using the uniform retaining member 130, the retaining force of the electrode stack 120 is further improved.

[0128] In addition, by covering the electrode surface 120a of the electrode stack 120 with a rubber elastic body before arranging the electrode stack 120 inside the can body 110, the electrode surface 120a of the electrode stack 120 will not directly contact the edge or wall of the can body 110. When an impact is applied, the rubber elastic body and the metal-covered hollow beads 1 act as buffers, thereby suppressing damage to the electrode stack 120.

[0129] [Metal-coated hollow beads]

[0130] Figure 2It is a cross-sectional view showing metal-coated hollow beads according to a second embodiment of the present invention.

[0131] like Figure 2 As shown, the metal-coated hollow bead 1 of this embodiment includes a hollow bead 2, a metal layer 3, and a fluid 4. The metal layer 3 is formed on the entire outer peripheral surface 2a of the hollow bead 2. The fluid 4 is enclosed in the inner space 2b of the hollow bead 2.

[0132] The hollow beads 2 are made of a thermoplastic resin. Examples of the thermoplastic resin include polyethylene (PE), polypropylene (PP), acrylic resin (methyl methacrylate, PMMA), polyamide (PA), acrylonitrile-butadiene-styrene (ABS), polyethylene terephthalate (PET), and polyacetal (POM).

[0133] The hollow beads 2 are made of a thermoplastic resin and enclose the fluid 4, thus expanding when heated. The temperature at which the hollow beads 2 expand when heated is preferably 100°C or higher. Heating to 100°C or higher expands the fluid 4 within the internal space 2b of the hollow beads 2, causing the hollow beads 2 to expand. Furthermore, the hollow beads 2 that have expanded due to heating maintain their expanded shape even when the temperature is lowered.

[0134] 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. Specifically, the hollow beads 2 more preferably have a volume expansion coefficient due to heating of 10% or more and 300% or less. Therefore, the second volume of the metal-coated hollow beads 1 after heating 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 are placed in a gap between two components and heated, the gaps between the expanded metal-coated hollow beads 1 widen due to the heat. Consequently, the pressure exerted by the expanded metal-coated hollow beads 1 on the two components becomes uneven.

[0135] The metal layer 3 includes 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 may be composed of two or more of these metals.

[0136] By including at least one selected from copper, aluminum, nickel, tin, silver, and gold, the metal layer 3 improves its heat dissipation and thermal conductivity, suppressing heat buildup. Furthermore, when the metal-coated hollow bead 1 is heated, heat is evenly transferred throughout the entire metal-coated hollow bead 1. This also increases the rigidity of the metal-coated hollow bead 1. For example, when a metal-coated hollow bead 1 is heated while positioned in a gap between two components, the expanded metal-coated hollow bead 1 applies pressure to the two components, holding one component relative to the other. Compared to hollow beads without a metal layer, the metal-coated hollow bead 1 exhibits higher rigidity, resulting in increased holding and pressing force.

[0137] The thickness of the metal layer 3 is defined by the following formula (1).

[0138] (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)

[0139] By defining the thickness of the metal layer 3 using the above formula (1), the hollow beads 2 expand under heating and the metal layer 3 also extends, thereby increasing the diameter of the hollow beads 2 without separating the metal layer 3 from the hollow beads 2 .

[0140] Preferred combinations of the material of the hollow bead 2 and the material of the metal layer 3 include, for example, material of the metal layer 3 / material of the hollow bead 2 = nickel / polyethylene terephthalate, tin / polypropylene, copper / polyamide, tin / polyethylene, etc. Preferred values ​​for the thickness ratio ((thickness of the metal layer) / (thickness of the outer shell of the hollow bead)) in these combinations are shown in Table 1.

[0141] 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 due to heating, and the bead diameter can be increased while suppressing separation of the metal layer 3 .

[0142] Table 1

[0143]

[0144] As the fluid 4, a gas or a liquid is used. Examples of the gas include neutral gases such as air and nitrogen, and inert gases such as argon and helium. Among them, nitrogen is preferred. If the fluid is nitrogen, when the temperature of the battery equipped with the metal-coated hollow beads 1 rises to a predetermined temperature or higher, the metal-coated hollow beads 1 rupture, filling the battery with nitrogen and blocking oxygen, thereby delaying the time to ignition and suppressing the spread of fire caused by ignition. Examples of the liquid include low-boiling-point solvents such as ethylene carbonate and propylene carbonate having a boiling point of about 110°C to 170°C.

[0145] The metal-coated hollow beads 1 preferably contain a material that expands the hollow beads 2 due to phase change within the internal space 2b of the hollow beads 2. Here, phase change refers to thermal change or the like.

[0146] According to the metal-coated hollow beads 1 of this embodiment, for example, when the metal-coated hollow beads 1 are heated while being positioned in the gap between two components, the expanded metal-coated hollow beads 1 apply pressure to the two components, thereby holding one component relative to the other. Specifically, as described above, by positioning the metal-coated hollow beads 1 in the gap between the can 110 and the electrode stack 120 and filling the gap with the metal-coated hollow beads 1, the metal-coated hollow beads 1 act as a buffer for the electrode stack 120, thereby preventing damage to the electrode stack 120.

[0147] When thermoplastic resin materials such as polypropylene, polystyrene, and polyethylene terephthalate, or glass materials, are heated and the temperature rises, their storage modulus / Young's modulus becomes extremely low, reaching a temperature at which they exhibit significant expansion under low stress. This temperature is called the glass transition point. When the resin material is significantly deformed above the glass transition point and the temperature is lowered while maintaining this deformation, the deformed state is retained. This shape-retention function is known as the shape memory effect. Based on this phenomenon, when applied to metal-coated hollow beads 1, normal elastic deformation occurs below the glass transition point, but superelastic deformation (large deformation under low stress) occurs above the glass transition point, resulting in a significantly expanded state of the metal-coated hollow beads 1. When the temperature is lowered from this state, the expanded diameter decreases slightly as the internal pressure decreases. When the temperature is lowered below the glass transition point, the deformation at a temperature slightly above the glass transition point is maintained while transitioning to a state with a higher storage modulus / Young's modulus, thereby fixing the large deformation (shape memory effect). Therefore, even if the temperature is lowered, the material will not return to its original state before being heated above the glass transition point. Shape memory materials (metals, resins) utilize this property.

[0148] [Filling component]

[0149] Figure 3 It is a cross-sectional view showing a filling member according to a second embodiment of the present invention.

[0150] like Figure 3 As shown, the filling member 10 of this embodiment includes 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 in the rubber elastic body 11 .

[0151] 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, it is possible to suppress the metal-coated hollow beads 1 from being crushed in the rubber elastic body 11.

[0152] 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), when 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. Furthermore, in a heated state, the metal-coated hollow beads 1 themselves can expand and rupture around the specified temperature of thermal runaway.

[0153] The thickness of the rubber elastic body 11 is preferably greater than 50 μm. If the thickness of the rubber elastic body 11 is less than 50 μm, the rubber elastic body 11 cannot stand on its own and may bend or wrinkle, preventing uniform pressure from being applied when heated, leading to the possibility of damage.

[0154] 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 is weaker than the expansion force of the rubber elastic body 11, and the metal-coated hollow beads 1 cannot expand within the rubber elastic body 11. If the content of the metal-coated hollow beads 1 exceeds 80% by volume, the amount of rubber elastic body 11 decreases, and the filling member cannot stand upright 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.

[0155] According to the filling member 10 of this embodiment, for example, when the filling member 10 disposed in the gap between two members is heated, the expanded filling member 10 pressurizes the two members, thereby holding one member relative to the other member.

[0156] [Can-type battery]

[0157] Figure 4 : is a cross-sectional view showing a can-type battery according to a fourth embodiment of the present invention. Figure 4 In, with Figure 1 The same structures as shown are denoted by the same reference numerals, and description thereof will be omitted.

[0158] like Figure 4 As shown, 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 formed of the filling member 10 of the above-described embodiment.

[0159] 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.

[0160] 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 can be made within the scope of the gist of the present invention described in the claims.

[0161] Example

[0162] Hereinafter, the present invention will be further specifically described with reference to Examples, but the present invention is not limited to the following Examples.

[0163] [Example]

[0164] A microbubble generator was placed in water to generate nitrogen microbubbles. While the water containing the nitrogen microbubbles was stirred, styrene monomer and a polymerization initiator were added to the water to produce nitrogen-containing hollow beads. Polymerization of the styrene monomer initiated at the interface between the water and nitrogen, resulting in nitrogen-containing hollow beads with a particle size of 50 μm.

[0165] The surfaces of the obtained nitrogen-containing hollow beads were plated with tin by a plating method to obtain metal-coated hollow beads having a tin plating layer formed on the surfaces of the nitrogen-containing hollow beads.

[0166] The obtained metal-coated hollow beads and the electrode stack were placed in a can. The proportion of the metal-coated hollow beads to the total volume of the gap between the can and the electrode stack (100% by volume) was 62% by volume.

[0167] The expansion rate of the metal-coated hollow beads in the container was measured while heating the metal-coated hollow beads at room temperature (25°C) to 130°C. Figure 5 Shown in.

[0168] according to Figure 5 The results shown show that the expansion rate of the metal-coated hollow beads increases at 100° C. or higher, and the metal-coated hollow beads expand by 5% or more relative to the state before heating.

Claims

1. A can-type battery, wherein: The can type battery comprises: an electrode stack housed in a can and consisting of a positive electrode, a negative electrode, and an electrolyte layer; and a holding member disposed in a gap between the can and the electrode stack and holding the electrode stack in the can, The retaining member is a metal-covered hollow bead or a filling member, the metal-covered hollow bead includes a hollow bead made of a thermoplastic resin, a metal layer formed on the outer peripheral surface of the hollow bead, and a fluid enclosed in the internal space of the hollow bead, and the second volume after heating is larger than the first volume before heating, and the metal-covered hollow bead pressurizes the stack in the stacking direction by the increase in volume, and the filling member includes a rubber elastic body and the metal-covered hollow bead contained in the rubber elastic body.

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

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

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

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

6. The can-type battery according to claim 1, wherein The temperature at which the hollow beads expand under heating is above 100°C.

7. The can-type battery according to claim 1, wherein The metal layer includes at least one selected from copper, aluminum, nickel, tin, silver, and gold.

8. The can-type battery according to claim 7, wherein The thickness of the metal layer is determined 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. The can-type battery according to claim 1, wherein The average particle size (D50) of the hollow beads before heating is 50 μm or less, and the average particle size (D50) of the hollow beads after heating is more than 50 μm and 200 μm or less.

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

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. The can-type battery according to claim 1, wherein The rubber elastic body has a thickness of 50 μm or more.

13. 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 method for manufacturing a can-type battery, wherein: The manufacturing method of the can type battery comprises: The process of disposing an electrode stack composed of a positive electrode, a negative electrode, and an electrolyte layer inside the can; a step of disposing a holding member in a gap between the can and the electrode stack; and a step of heating the holding member to expand the holding member, pressurizing the electrode stack in a stacking direction by the holding member, and holding the electrode stack in the can body by the holding member; The retaining member is a metal-covered hollow bead or a filling member, the metal-covered hollow bead includes a hollow bead made of a thermoplastic resin, a metal layer formed on the outer peripheral surface of the hollow bead, and a fluid enclosed in the internal space of the hollow bead, and the second volume after heating is larger than the first volume before heating, and the metal-covered hollow bead pressurizes the stack in the stacking direction by the increase in volume, and the filling member includes a rubber elastic body and the metal-covered hollow bead contained in the rubber elastic body.

15. The method for manufacturing a can-type battery according to claim 14, wherein: The method for manufacturing a can-type battery includes, before the step of arranging the electrode stack, a step of arranging an insulator between at least one of 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, wherein: The method for manufacturing a can-type battery includes, before the step of arranging the electrode stack, a step of arranging an insulator covering an electrode surface of the electrode stack.

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