Cylindrical battery

Abstract

The present invention is characterized in that: a sealing body (30) comprises a rupture disc (31) that is crimped and fixed to an opening (24) via a gasket (34), and a terminal plate (32) that is disposed on the inner surface side of the rupture disc (31) and is electrically connected to the rupture disc (31) at a radially central part; the rupture disc (31) has a valve part (31A) that deforms if the internal pressure exceeds a prescribed threshold value; and in a region radially outward of the valve part (31A), the rupture disc (31) and the terminal plate (32) are joined via an adhesive layer (33) composed of an insulating adhesive.

Description

Cylindrical battery

[0001] The present disclosure relates to cylindrical batteries.

[0002] The cylindrical battery includes a cylindrical outer can with a bottom that houses an electrode assembly including a positive electrode and a negative electrode, and a sealing body that closes the opening of the outer can. The sealing body of the cylindrical battery disclosed in Patent Document 1 has a structure in which a rupture plate and a terminal plate are stacked with a plate-shaped insulating member interposed therebetween. In the sealing body of Patent Document 1, when the internal pressure of the cylindrical battery increases during an abnormality, the rupture plate deforms, breaking the internal terminal plate and interrupting the current path between the rupture plate and the internal terminal plate.

[0003] International Publication No. 2016 / 157749

[0004] However, from the viewpoint of improving productivity, it is desirable to reduce the number of parts and simplify the structure of cylindrical batteries. The sealing body of the cylindrical battery in Patent Document 1 is configured by fitting a terminal plate into a recess formed in a rupture plate via a plate-shaped insulating member. However, the sealing body of the cylindrical battery in Patent Document 1 still has room for improvement in terms of reducing the number of parts and simplifying the structure.

[0005] A cylindrical battery according to one aspect of the present disclosure comprises an electrode assembly including a positive electrode and a negative electrode, a cylindrical outer can with a bottom that houses the electrode assembly, and a sealing body that closes the opening of the outer can, wherein the sealing body includes a rupture plate that is fixed to the opening by crimping via a gasket, and a terminal plate that is disposed on the inner surface of the rupture plate and is electrically connected to the rupture plate at its radial center, and the rupture plate has a valve portion that deforms when the internal pressure exceeds a predetermined threshold, and the rupture plate and the terminal plate are joined together in a region radially outward of the valve portion via an adhesive layer made of an insulating adhesive.

[0006] According to a cylindrical battery according to one aspect of the present disclosure, it is possible to reduce the number of parts and simplify the structure, thereby providing a cylindrical battery with high productivity.

[0007] 1 is an axial cross-sectional view of a cylindrical battery according to an embodiment of the present invention; FIG. 2 is an enlarged view of the vicinity of the sealing body of the cylindrical battery in FIG.

[0008] Hereinafter, an example of an embodiment of a cylindrical battery according to the present disclosure will be described in detail with reference to the drawings. The embodiment described below is merely an example, and the present disclosure is not limited to the following embodiment. Furthermore, the present disclosure also includes configurations obtained by selectively combining the components of the embodiments described below.

[0009] Fig. 1 is an axial cross-sectional view of a cylindrical battery 10 according to an embodiment. As shown in Fig. 1, the cylindrical battery 10 includes an electrode assembly 14, a non-aqueous electrolyte (not shown), and an outer can 20 that houses the electrode assembly 14 and the non-aqueous electrolyte. The outer can 20 is a cylindrical metal container that is open on one axial side and has a bottom, and an opening 24 of the outer can 20 is closed by a sealing body 30. Hereinafter, the side of the sealing body 30 in the axial direction (height direction) of the cylindrical battery 10 will be referred to as "upper," and the side of the bottom 21 of the outer can 20 in the axial direction will be referred to as "lower."

[0010] The electrode assembly 14 includes a positive electrode 11, a negative electrode 12, and a separator 13, and is configured such that the positive electrode 11 and the negative electrode 12 are spirally wound with the separator 13 interposed therebetween. The positive electrode 11, the negative electrode 12, and the separator 13 are all strip-shaped, long bodies that are spirally wound and alternately stacked in the radial direction of the electrode assembly 14. The negative electrode 12 is formed to be slightly larger than the positive electrode 11 to prevent lithium deposition. That is, the negative electrode 12 is formed to be longer in the longitudinal direction and width direction (short direction) than the positive electrode 11. The separator 13 is formed to be at least slightly larger than the positive electrode 11, and two separators 13 are arranged to sandwich the positive electrode 11. The cylindrical battery 10 includes insulating plates 16 and 17 arranged above and below the electrode assembly 14, respectively.

[0011] The positive electrode 11 has a positive electrode core and a positive electrode mixture layer formed on the positive electrode core. The positive electrode core can be a foil of a metal, such as aluminum or an aluminum alloy, that is stable within the potential range of the positive electrode 11, or a film with such a metal disposed on the surface. The positive electrode mixture layer contains a positive electrode active material, a conductive agent, and a binder, and is preferably formed on both sides of the positive electrode core except for the exposed portion of the positive electrode core to which the positive electrode lead 18 is welded. The positive electrode 11 can be produced, for example, by applying a positive electrode mixture slurry containing a positive electrode active material, a conductive agent, a binder, etc. to the positive electrode core, drying the coating, and then compressing it to form a positive electrode mixture layer on both sides of the positive electrode core.

[0012] The positive electrode mixture layer contains particulate lithium metal composite oxide as a positive electrode active material. The lithium metal composite oxide is a composite oxide containing metal elements such as Co, Mn, Ni, and Al in addition to Li. The metal element constituting the lithium metal composite oxide is, for example, at least one selected from Mg, Al, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Y, Zr, Sn, Sb, W, Pb, and Bi. Among them, it is preferable to contain at least one selected from Co, Ni, and Mn. Examples of suitable composite oxides include lithium metal composite oxides containing Ni, Co, and Mn, and lithium metal composite oxides containing Ni, Co, and Al.

[0013] Examples of conductive agents contained in the positive electrode mixture layer include carbon black such as acetylene black and ketjen black, graphite, carbon nanotubes (CNT), carbon nanofibers, graphene, and other carbon materials. Examples of binders contained in the positive electrode mixture layer include fluorine-containing resins such as polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), polyimide, acrylic resin, polyolefin, and the like. These resins may also be used in combination with carboxymethyl cellulose (CMC) or a salt thereof, polyethylene oxide (PEO), and the like.

[0014] The negative electrode 12 has a negative electrode core and a negative electrode mixture layer formed on the negative electrode core. The negative electrode core can be a foil of a metal, such as copper or a copper alloy, that is stable within the potential range of the negative electrode 12, or a film with such a metal disposed on the surface. The negative electrode mixture layer contains a negative electrode active material, a binder, and, if necessary, a conductive agent, and is preferably formed on both sides of the negative electrode core except for the exposed portion of the negative electrode core to which the negative electrode lead 19 is welded. The negative electrode 12 can be produced by applying a negative electrode mixture slurry containing a negative electrode active material and a binder to the surface of the negative electrode core, drying the coating, and then compressing it to form a negative electrode mixture layer on both sides of the negative electrode core.

[0015] The negative electrode mixture layer generally contains, as the negative electrode active material, a carbon material that reversibly absorbs and releases lithium ions. Suitable examples of the carbon material include natural graphite such as flake graphite, lump graphite, and amorphous graphite, and artificial graphite such as lump artificial graphite (MAG) and graphitized mesophase carbon microbeads (MCMB). Furthermore, as the negative electrode active material, a material containing at least one of an element that alloys with Li, such as Si or Sn, and a material containing such an element may be used. Among these, a composite material containing Si is preferred.

[0016] A suitable example of a composite material containing Si is SiO ２ Examples of such composite materials include a material in which Si fine particles are dispersed in a silicate phase such as lithium silicate, or a material in which Si fine particles are dispersed in an amorphous carbon phase. A conductive layer such as a carbon coating is formed on the particle surfaces of the composite material.

[0017] As in the case of the positive electrode mixture layer, the binder contained in the negative electrode mixture layer can be a fluorine-containing resin, PAN, polyimide, acrylic resin, polyolefin, or the like, but styrene-butadiene rubber (SBR) is preferably used. The negative electrode mixture layer preferably contains CMC or a salt thereof, polyacrylic acid (PAA) or a salt thereof, polyvinyl alcohol (PVA), or the like. Among these, it is preferable to use SBR in combination with CMC or a salt thereof, PAA or a salt thereof, or the like. The negative electrode mixture layer may contain a conductive agent such as CNT.

[0018] The separator 13 is a porous sheet having ion permeability and insulating properties. Specific examples of the porous sheet include a microporous thin film, a woven fabric, and a nonwoven fabric. Suitable materials for the separator 13 include polyolefins such as polyethylene and polypropylene, and cellulose. The separator 13 may have a single-layer structure or a multi-layer structure. A highly heat-resistant resin layer such as an aramid resin may be formed on the surface of the separator 13. A filler layer containing an inorganic filler may be formed at the interface between the separator 13 and at least one of the positive electrode 11 and the negative electrode 12.

[0019] As described above, the positive electrode lead 18 is connected to the positive electrode 11, and the negative electrode lead 19 is connected to the winding end side of the negative electrode 12. The positive electrode lead 18 passes through a through hole in the insulating plate 16 and extends toward the sealing body 30, and the negative electrode lead 19 passes outside the insulating plate 17 and extends toward the bottom 21 of the outer can 20. The positive electrode lead 18 is connected to the underside of the terminal plate 32 of the sealing body 30 by welding or the like, and the sealing body 30 serves as a positive electrode terminal. The negative electrode lead 19 is connected to the inner surface of the bottom 21 of the metal outer can 20 by welding or the like, and the outer can 20 serves as a negative electrode terminal.

[0020] The non-aqueous electrolyte contained in the exterior can 20 has lithium ion conductivity. The non-aqueous electrolyte may be a liquid electrolyte (electrolytic solution) or a solid electrolyte.

[0021] The liquid electrolyte (electrolytic solution) contains a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. Examples of the non-aqueous solvent include esters, ethers, nitriles, amides, and mixed solvents of two or more of these. Examples of the non-aqueous solvent include ethylene carbonate (EC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and mixed solvents of these. The non-aqueous solvent may contain a halogen-substituted compound (e.g., fluoroethylene carbonate) in which at least a portion of the hydrogen atoms of these solvents are substituted with halogen atoms such as fluorine. Examples of the electrolyte salt include LiPF ６ Lithium salts such as

[0022] As the solid electrolyte, for example, a solid or gel-like polymer electrolyte, an inorganic solid electrolyte, etc. can be used. As the inorganic solid electrolyte, a material known in all-solid-state lithium ion secondary batteries, etc. (for example, an oxide-based solid electrolyte, a sulfide-based solid electrolyte, a halogen-based solid electrolyte, etc.) can be used. The polymer electrolyte includes, for example, a lithium salt and a matrix polymer, or a non-aqueous solvent, a lithium salt, and a matrix polymer. As the matrix polymer, for example, a polymer material that absorbs the non-aqueous solvent and gels is used. As the polymer material, for example, a fluororesin, an acrylic resin, a polyether resin, etc. can be used.

[0023] As described above, the exterior can 20 is a cylindrical metal container with a bottom that is open on one axial side. The exterior can 20 has a bottom 21 and side surfaces 22 that form the side surfaces of the cylindrical batteries 10. The side surfaces 22 are the portions of the exterior can 20 excluding the bottom 21, and include grooved portions 23 and openings 24 described below.

[0024] The grooved portion 23 is a portion of the side surface portion 22 recessed radially inward, and is provided in an annular shape along the circumferential direction of the outer can 20. The upper surface of the grooved portion 23 supports the sealing body 30. The grooved portion 23 can be formed, for example, by spinning a portion of the side surface portion 22 radially inward to recess it in an annular shape radially inward.

[0025] The opening 24 is a region of the side surface portion 22 above the grooved portion 23, and forms an opening in the outer can 20. The opening 24 is bent radially inward when the sealing body 30 is crimped to the outer can 20. As a result, the opening 24 is formed with an opening side surface portion 25 that forms part of the side surface of the cylindrical battery 10 and covers the outer peripheral surface of the gasket 34, and a crimped portion 26 that forms part of the top surface of the cylindrical battery 10 and extends radially inward.

[0026] The gasket 34 is a flexible insulating member that electrically isolates the sealing body 30, which is the positive electrode terminal, from the outer can 20, which is the negative electrode terminal, while being compressed in the vertical direction to ensure the airtightness of the interior of the outer can 20. The material of the gasket 34 is not particularly limited as long as it is a compressible insulating material, and examples that can be used include polypropylene (PP), polyphenylene sulfide (PPS), polyethylene (PE), polybutylene terephthalate (PBT), perfluoroalkoxyalkane (PFA), polytetrafluoroethylene (PTFE), and polyamide (PA).

[0027] Next, the sealing body 30 will be described in detail with reference to Fig. 2. Fig. 2 is an enlarged view of the sealing body 30 and its vicinity in Fig. 1 .

[0028] 2, the sealing body 30 is crimped to the top of the cylindrical battery 10 and closes the opening 24 of the outer can 20. The sealing body 30 includes a rupture plate 31 that is crimped to the opening 24 via a gasket 34, and a terminal plate 32 that is disposed on the inner surface of the rupture plate 31. In other words, the sealing body 30 has a structure in which the terminal plate 32 and the rupture plate 31 are stacked in this order from the electrode body 14 side.

[0029] The rupture plate 31 and the terminal plate 32 abut against each other at their radial centers, thereby electrically connecting the rupture plate 31 and the terminal plate 32. The rupture plate 31 and the terminal plate 32 are joined together at their radial centers by, for example, laser welding.

[0030] The rupture plate 31 is a metal member having a circular shape in a plan view. The rupture plate 31 has a valve portion 31A that deforms when the internal pressure of the cylindrical battery 10 exceeds a predetermined threshold, and an outer peripheral portion 31B provided on the outer periphery of the valve portion 31A. The rupture plate 31 can be produced, for example, by pressing a plate made of a metal such as aluminum or an aluminum alloy.

[0031] When an abnormality occurs in a cylindrical battery 10 and the internal pressure rises, the generated high-temperature gas moves upward through the vent hole 32A in the terminal plate 32. This pushes the rupture plate 31 upward, deforming the valve portion 31A so that it protrudes toward the outside of the cylindrical battery 10. This then causes the easily breakable portion 32B of the terminal plate 32, described below, to break, and a portion of the terminal plate 32 is detached. As a result, the current path in the sealing body 30 is interrupted.

[0032] The valve portion 31A of the rupture plate 31 includes a joint portion 31C located at the radial center and abutting against the terminal plate 32, and a thin-walled portion 31D formed outside the joint portion 31C. The valve portion 31A has a circular shape in a plan view and has a diameter, for example, 50% to 80% of the outer diameter of the rupture plate 31. The joint portion 31C is configured to be thicker than other portions. The thickness of the joint portion 31C can be appropriately set depending on the thickness of the adhesive layer 33 described below. The thin-walled portion 31D is formed in an annular shape and serves as a starting point for deformation of the valve portion 31A when the internal pressure increases. In this embodiment, the thickness of the thin-walled portion 31D decreases radially outward. Note that the configuration of the thin-walled portion 31D is not limited to this as long as it can deform the valve portion 31A when the internal pressure increases.

[0033] The outer peripheral portion 31B is provided around the valve portion 31A, and a portion thereof is crimped and fixed to the opening 24 via a gasket 34. In this embodiment, the lower surface of the outer peripheral portion 31B is flat. That is, the region of the inner surface (lower surface) of the rupture plate 31 radially outward from the thin-walled portion 31D is formed flat. As will be described in detail later, the rupture plate 31 and the terminal plate 32 are joined to the rupture plate 31 via an adhesive layer 33 made of an adhesive. That is, the terminal plate 32 is not mechanically fitted to the rupture plate 31. Therefore, there is no need to provide a recess or the like for fitting and fixing the terminal plate 32 to the rupture plate 31, and the structure of the rupture plate 31 can be simplified. For example, by flattening the lower surface of the outer peripheral portion 31B as in this embodiment, molding of the rupture plate 31 is facilitated, improving productivity.

[0034] The terminal plate 32 is a metal member having a circular shape in a plan view, similar to the rupture plate 31. The terminal plate 32 has an outer diameter that is slightly smaller than that of the rupture plate 31, for example, a diameter that is 50% to 80% of the outer diameter of the rupture plate 31. The terminal plate 32 has a vent hole 32A through which high-temperature gas generated when the internal pressure increases passes. The vent hole 32A is provided, for example, in the shape of a ring in a plan view. The shape and arrangement of the vent hole 32A are not particularly limited.

[0035] The terminal plate 32 has an easily breakable portion 32B that breaks when the internal pressure of the cylindrical battery 10 increases. In this embodiment, the easily breakable portion 32B is a thin-walled portion formed by providing a generally V-shaped recess on the upper surface of the terminal plate 32. The recess may also be provided on the lower surface of the terminal plate 32. The shape of the recess is not limited to a generally V-shaped cross section. The easily breakable portion 32B is, for example, annular in plan view. The terminal plate 32 abuts against the rupture plate 31 in a region radially inward of the easily breakable portion 32B, but does not abut against the rupture plate 31 in a region radially outward of the easily breakable portion 32B. The positive electrode lead 18 is joined to a region of the lower surface of the terminal plate 32 radially outward of the easily breakable portion 32B.

[0036] When an abnormality occurs in a cylindrical battery 10 and the internal pressure rises, the rupture plate 31 is pushed upward, causing the valve portion 31A to deform and protrude toward the outside of the cylindrical battery 10. When this happens, the fragile portion 32B breaks first, and the area of ​​the terminal plate 32 that is inside the fragile portion 32B is separated from the area outside the fragile portion 32B. As described above, only the area of ​​the terminal plate 32 that is radially inside the fragile portion 32B abuts against the rupture plate 31. Therefore, when the terminal plate 32 is separated, the current path is interrupted.

[0037] As shown in FIG. 2 , the terminal plate 32 is joined to the rupture plate 31 via an adhesive layer 33 made of an insulating adhesive. In other words, there is no plate-shaped insulating member between the rupture plate 31 and the terminal plate 32, as is the case with prior art. This reduces the number of components in the sealing body 30. Furthermore, by providing the adhesive layer 33 made of an insulating adhesive, when the internal pressure increases and the fragile portion 32B of the terminal plate 32 ruptures, the insulation between the rupture plate 31 and the terminal plate 32 is ensured, while preventing the terminal plate 32 from falling off the rupture plate 31. As a result, a highly reliable cylindrical battery 10 can be achieved.

[0038] Examples of insulating adhesives that can be used to form the adhesive layer 33 include hot melt adhesives, epoxy resin adhesives, acrylic resin adhesives, urethane resin adhesives, silicone resin adhesives, rubber adhesives, and UV-curing adhesives.

[0039] Adhesive layer 33 joins rupture plate 31 and terminal plate 32 in a region radially outward of valve portion 31A. This allows rupture plate 31 to hold the region outward of easily breakable portion 32B of terminal plate 32 when valve portion 31A deforms and easily breakable portion 32B of terminal plate 32 breaks.

[0040] In a plan view of the sealing body 30, the adhesive layer 33 is provided in an area where the terminal plate 32 overlaps with the area radially outward of the valve portion 31A of the rupture plate 31. This prevents the terminal plate 32 from contacting the rupture plate 31 when the valve portion 31A deforms and the fragile portion 32B of the terminal plate 32 breaks. Furthermore, the configuration of the present invention reduces the area required for insulation between the rupture plate 31 and the terminal plate 32, while still allowing the current path to be interrupted in the event of an abnormality, compared to the prior art, when a plate-shaped insulating member is provided. The adhesive layer 33 is preferably provided around the entire circumference of the cylindrical battery 10. This strengthens the bond between the rupture plate 31 and the terminal plate 32. Furthermore, in a plan view of the sealing body 30, the area of ​​the portion where the adhesive layer 33 is provided is preferably 5% or more of the area of ​​the outer diameter of the terminal plate 32. In this case, the bond between the rupture plate 31 and the terminal plate 32 is stronger, and the terminal plate 32 is prevented from falling off from the rupture plate 31. Furthermore, in a plan view of the sealing body 30, the area of ​​the portion where the adhesive layer 33 is disposed is preferably 20% or less of the area of ​​the outer diameter of the terminal plate 32. In this case, the amount of adhesive to be applied can be reduced, thereby improving productivity. Therefore, in a plan view of the sealing body 30, the area of ​​the portion where the adhesive layer 33 is disposed is preferably 5% or more and 20% or less of the area of ​​the outer diameter of the terminal plate 32.

[0041] The cylindrical battery 10 of the present disclosure does not have a plate-shaped insulating member between the rupture plate 31 and the terminal plate 32, as used in, for example, Patent Document 1. This allows the axial length of the cylindrical battery 10 to be reduced, making it easier to miniaturize the cylindrical battery 10. The thickness of the adhesive layer 33 is, for example, 0.1 mm or more and 3 mm or less, or may be 0.2 mm or more and 2 mm or less. Reducing the thickness of the adhesive layer 33 makes it easier to miniaturize the cylindrical battery 10.

[0042] The present disclosure is further described by the following embodiments. Configuration 1: A cylindrical battery comprising: an electrode assembly including a positive electrode and a negative electrode; a cylindrical outer can with a bottom that houses the electrode assembly; and a sealing body that closes an opening of the outer can, wherein the sealing body includes a rupture plate that is crimped to the opening via a gasket; and a terminal plate that is disposed on the inner surface of the rupture plate and electrically connects to the rupture plate at a radially central portion thereof, the rupture plate having a valve portion that deforms when internal pressure exceeds a predetermined threshold, and the rupture plate and the terminal plate are joined to each other in a region radially outward of the valve portion via an adhesive layer made of an insulating adhesive. Configuration 2: The cylindrical battery according to Configuration 1, wherein the adhesive layer is provided around the entire circumference. Configuration 3: The cylindrical battery according to Configuration 1 or 2, wherein, in a plan view of the sealing body, the area of ​​the portion where the adhesive layer is disposed is 5% to 20% of the area of ​​the outer diameter of the terminal plate. Configuration 4: The cylindrical battery according to any one of configurations 1 to 3, wherein the rupture plate has a thin-walled portion that is annular in plan view, and an area of ​​the inner surface of the rupture plate that is radially outward from the thin-walled portion is flat.

[0043] 10 Cylindrical battery, 11 Positive electrode, 12 Negative electrode, 13 Separator, 14 Electrode body, 16, 17 Insulating plate, 18 Positive electrode lead, 19 Negative electrode lead, 20 Outer can, 21 Bottom, 22 Side portion, 23 Grooved portion, 24 Opening, 25 Opening side portion, 26 Crimping portion, 30 Sealing body, 31 Rupture plate 31, 31A Valve portion, 31B Outer periphery, 31C Joint portion, 31D Thin portion, 32 Terminal plate, 32A Vent, 32B Easy-to-break portion, 33 Adhesive layer, 34 Gasket.

Claims

an electrode assembly including a positive electrode and a negative electrode; a cylindrical outer can with a bottom that houses the electrode assembly; a sealing body that closes the opening of the outer can; Equipped with The sealing body is a rupture plate that is fixed to the opening by crimping via a gasket; A terminal plate disposed on the inner surface side of the rupture plate and electrically connected to the rupture plate at a radial center portion; Including, The rupture plate has a valve portion that deforms when the internal pressure exceeds a predetermined threshold, A cylindrical battery, wherein the rupture plate and the terminal plate are joined via an adhesive layer made of an insulating adhesive in an area radially outward of the valve portion. 　 The cylindrical battery according to claim 1 , wherein the adhesive layer is provided over the entire periphery.

2. The cylindrical battery according to claim 1, wherein the area of ​​the portion where the adhesive layer is disposed in a plan view of the sealing body is 5% to 20% of the area of ​​the outer diameter of the terminal plate. 　 The rupture plate has a thin-walled portion that is annular in plan view, The cylindrical battery according to claim 1 , wherein an area of ​​the inner surface of the rupture plate that is radially outward from the thin-walled portion is flat.

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