Cylindrical battery

Abstract

Provided is a cylindrical battery (10) comprising an electrode body (14), an outer can (16) that is in the form of a bottomed cylinder and accommodates the electrode body (14), a sealing body (17) that closes an opening of the outer can (16), a collector plate (32) that is disposed between the sealing body (17) and the electrode body (14), and a metal plate (40) that is bonded to the surface of the collector plate (32) on the sealing-body (17) side, the cylindrical battery (10) being characterized in that: the metal plate (40) has a top portion (43) and a side-surface portion (44), the metal plate (40) also having a protruding portion (41) that is provided in the central portion of the metal plate (40), and a flange portion (42) that is provided around the protruding part (41); and the top portion (43) is bonded to the sealing body (17).

Description

Cylindrical battery

[0001] The present disclosure relates to cylindrical batteries.

[0002] A cylindrical battery generally includes a wound electrode assembly, a cylindrical outer can with a bottom that houses the electrode assembly, and a sealing body that closes the opening of the outer can. Patent Document 1 discloses a cylindrical battery that includes a current collector plate inside the outer can to which a positive electrode lead extending from the positive electrode of the electrode assembly is connected.

[0003] International Publication No. 2023 / 281973

[0004] In cylindrical batteries, for example, if an external short circuit occurs while the battery is being charged, a large current may be applied to the electrode body, causing the electrode body to overheat. This may generate gas inside the battery, increasing the internal pressure of the battery and causing the sealing body to deform toward the outside of the battery. If the sealing body deforms toward the outside of the battery, gas may be ejected from the sealing body side, which may be undesirable from the perspective of ensuring battery safety.

[0005] Furthermore, when a load is applied from the outside of the battery toward the inside of the battery, the sealing body or the current collector plate may bend and deform toward the inside of the battery. If the sealing body or the current collector plate bends and deforms toward the inside of the battery, the sealing body or the current collector plate may come into contact with the electrode plate of the electrode assembly, causing an internal short circuit and impairing battery performance. Furthermore, if an internal short circuit occurs, a large current may be applied to the electrode assembly, causing the electrode assembly to generate abnormal heat, as in the case of the external short circuit described above.

[0006] A cylindrical battery according to one aspect of the present disclosure is a cylindrical battery comprising: an electrode assembly in which a first electrode and a second electrode are wound with a separator interposed therebetween; a cylindrical outer can with a bottom that houses the electrode assembly; a sealing body that closes the opening of the outer can; a current collector plate that is disposed between the sealing body and the electrode assembly; and a metal plate that is joined to the surface of the current collector plate facing the sealing body, wherein the metal plate has a top and side portions, a convex portion provided in the center of the metal plate, and a flange portion provided around the convex portion, and the top portion is joined to the sealing body.

[0007] According to a cylindrical battery according to one aspect of the present disclosure, deformation of the sealing body and current collector plate can be suppressed, thereby ensuring the battery performance and safety of the cylindrical battery.

[0008] FIG. 1 is an axial cross-sectional view of a cylindrical battery of the first embodiment. FIG. 2 is a perspective view of an electrode body constituting the cylindrical battery of the first embodiment. FIG. 3 is a top view of a current collector plate constituting the cylindrical battery of the first embodiment. FIG. 4 is an axial cross-sectional view of a current collector plate constituting the cylindrical battery of the first embodiment. FIG. 5 is an axial cross-sectional view of a cylindrical battery of the second embodiment. FIG. 6 is a perspective view of an electrode body constituting the cylindrical battery of the second embodiment. FIG. 7 is a diagram showing a modified current collector plate constituting the cylindrical battery. FIG. 8 is a diagram showing a modified current collector plate constituting the cylindrical battery. FIG. 9 is a diagram showing a modified cylindrical battery.

[0009] 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.

[0010] [First embodiment] The configuration of a cylindrical battery 10 according to the first embodiment will be described with reference to Figures 1 and 2. Figure 1 is a schematic cross-sectional view of the cylindrical battery 10, and Figure 2 is a perspective view of an electrode assembly 14 that constitutes the cylindrical battery 10.

[0011] 1 and 2 , cylindrical battery 10 includes an electrode assembly 14 in which a first electrode and a second electrode are wound with a separator interposed therebetween, a nonaqueous electrolyte (not shown), an outer can 16 that houses electrode assembly 14 and the nonaqueous electrolyte, a sealing body 17 that closes the opening of outer can 16, a current collector 32 disposed between sealing body 17 and electrode assembly 14, and a metal plate 40 bonded to the upper surface of current collector 32. In this specification, the sealing body 17 side of cylindrical battery 10 is referred to as the "top," and the bottom 16A side of outer can 16 is referred to as the "bottom." The following description will be given of a case in which the first electrode is a positive electrode 11 and the second electrode is a negative electrode 112.

[0012] The electrode assembly 14 has a positive electrode 11, a negative electrode 12, and a separator 13, and has a structure in which 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 constituting the electrode assembly 14 are all long strips, and are spirally wound so that they are 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 in order to prevent lithium deposition. That is, the negative electrode 12 is formed to be longer in the longitudinal direction and width direction than the positive electrode 11. The separator 13 is formed to be slightly larger than the positive electrode 11 and the negative electrode 12, and, for example, two separators 13 are arranged to sandwich the positive electrode 11.

[0013] The electrode body 14 has a positive electrode lead 20 connected to the positive electrode 11 by welding or the like, and a negative electrode lead 21 connected to the negative electrode 12 by welding or the like. In this embodiment, the electrode body 14 has a plurality of positive electrode leads 20. The number of positive electrode leads 20 may be one. The number of negative electrode leads 21 may be one or more.

[0014] 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, excluding the exposed portion of the positive electrode core (not shown) to which the positive electrode lead 20 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.

[0015] 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, or lithium metal composite oxides containing Ni, Co, and Al.

[0016] 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.

[0017] 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. 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.

[0018] 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.

[0019] A suitable example of a composite material containing Si is SiO ２ Examples of the composite material 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 surface of the composite material. The combined use of a carbon material and a Si-containing composite material as the negative electrode active material is preferred from the viewpoint of achieving both high capacity and high durability of the battery.

[0020] 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.

[0021] 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.

[0022] The non-aqueous electrolyte has lithium ion conductivity and may be a liquid electrolyte (electrolytic solution) or a solid electrolyte.

[0023] 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

[0024] 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.

[0025] Insulating plates 18 and 19 are disposed above and below the electrode assembly 14. The positive electrode lead 20 extends toward the sealing member 17 through a through-hole 18A provided in the insulating plate 18 and a through-hole 32A provided in the current collector 32. The positive electrode lead 20 is bent to fit along the upper surface of the recess 34 of the current collector 32 and joined by welding or the like so as to be sandwiched between the current collector 32 and the metal plate 40. By sandwiching the positive electrode lead 20 between the current collector 32 and the metal plate 40, the positive electrode lead 20 is less likely to come off the surface of the current collector 32 and the workability of welding the positive electrode lead 20 can be improved. As will be described in detail later, the current collector 32 and the sealing member 17 are electrically connected. Therefore, the sealing member 17 serves as a positive electrode terminal. In this embodiment, the negative electrode lead 21 extends toward the bottom 16A of the outer can 16 through the outside of the insulating plate 19. The negative electrode lead 21 is joined to the inner surface of the bottom 16A of the outer can 16 by welding or the like. This makes the outer can 16 a negative electrode terminal. The negative electrode lead 21 may extend through the center of the insulating plate 19 toward the bottom 16A of the outer can 16. Alternatively, the negative electrode lead 21 may not be provided, and the negative electrode core may be exposed at the outermost periphery of the electrode body 14, and the negative electrode core may be abutted against the inner surface of the outer can 16.

[0026] The outer can 16 is a cylindrical metal container with a bottom and an opening on one axial side. The opening of the outer can 16 is closed by a sealing body 17. A gasket 24 is provided between the outer can 16 and the sealing body 17 to ensure airtightness inside the battery. The provision of the gasket 24 also ensures insulation between the outer can 16 and the sealing body 17. In other words, the gasket 24 serves as a sealing member to maintain airtightness inside the battery and as an insulating member to insulate the outer can 16 from the sealing body 17.

[0027] The exterior can 16 has a grooved portion 22 formed on a side wall that protrudes inward and supports the sealing body 17 and the current collector plate 32. The grooved portion 22 is preferably formed in an annular shape along the circumferential direction of the exterior can 16, and supports the sealing body 17 and the current collector plate 32 on its upper surface. The grooved portion 22 can be formed, for example, by spinning a portion of the side wall of the exterior can 16 radially inward to create a recess in the radial direction. The sealing body 17 and the current collector plate 32 are fixed to the top of the exterior can 16 by the grooved portion 22 and the open end of the exterior can 16 that is crimped to the sealing body 17.

[0028] The bottom 16A of the exterior can 16 is provided with a gas exhaust port that opens when the internal pressure of the cylindrical battery 10 reaches a predetermined pressure. In other words, in this embodiment, when the internal pressure of the battery increases due to abnormal heat generation in the electrode body 14 or the like, gas is released from the gas exhaust port provided in the bottom 16A of the exterior can 16.

[0029] The bottom 16A of the outer can 16 has, for example, an annular groove 23 formed therein, and the portion surrounded by the groove 23 serves as a gas outlet. The groove 23 may be C-shaped or the like when viewed from the bottom, but is preferably formed in a perfect circular shape when viewed from the bottom from the viewpoint of improving rupture resistance when the internal pressure increases. The groove 23 is, for example, an engraved mark formed on the outer surface side of the bottom 16A.

[0030] As described above, the sealing body 17 has the function of closing the opening of the outer can 16. In this embodiment, the sealing body 17 is composed of a single sealing plate 30. Note that the configuration of the sealing body 17 is not limited to this as long as it is capable of closing the opening of the outer can 16. The sealing body 17 may have a structure in which multiple members are stacked in the axial direction. The sealing body 17 may have, for example, a cap member on top of the sealing plate 30.

[0031] A protrusion 31 that protrudes toward the outside of the battery is provided in the center of the sealing plate 30. The protrusion 31 has a substantially circular shape when viewed from above. As will be described in detail later, the sealing plate 30 is joined to the metal plate 40 near the center of the sealing plate 30. Therefore, the diameter of the protrusion 31 provided on the sealing plate 30 is configured to be smaller than the diameter of the apex 43 provided on the metal plate 40. The height of the protrusion 31 is not particularly limited, but is, for example, 0.5 mm or more and 5.0 mm or less. The lower surface of the sealing plate 30 may have a flat shape over the entire surface.

[0032] The sealing plate 30 may be made of, for example, a metal containing aluminum as a main component. As described above, the sealing plate 30 is fixed to the opening of the outer can 16 by crimping via the gasket 24.

[0033] The current collecting plate 32 is disposed between the sealing plate 30 and the electrode body 14. The current collecting plate 32 has a peripheral edge portion 33 located on the outer periphery of the current collecting plate 32, and a recessed portion 34 provided radially inside the peripheral edge portion 33 and recessed downward relative to the peripheral edge portion 33.

[0034] The peripheral edge 33 has an annular shape and abuts against the underside of the sealing plate 30. The peripheral edge 33 is joined to the sealing plate 30 by laser welding. The number and area of ​​the welds between the peripheral edge 33 and the sealing plate 30 are set, for example, taking into consideration the joint strength and resistance. The peripheral edge 33 is crimped and fixed to the opening of the outer can 16 via the gasket 24. By crimping and fixing the peripheral edge 33 to the opening of the outer can 16, the current collecting plate 32 can be firmly fixed to the top of the outer can 16.

[0035] The recess 34 has a perfect circular shape when viewed from above. The positive electrode lead 20 is joined to the upper surface of the recess 34. The depth of the recess 34, i.e., the length along the axial direction from the upper surface of the peripheral portion 33 to the upper surface of the recess 34, is, for example, 0.1 mm or more and 5.0 mm or less. The recess 34 is flat and provided approximately parallel to the peripheral portion 33.

[0036] A through-hole 32A is provided in the center of the recess 34. As described above, the positive electrode lead 20 extending from the positive electrode 11 passes through the through-hole 32A. The size of the through-hole 32A can be set appropriately depending on the number, shape, etc. of the positive electrode leads 20. The diameter of the through-hole 32A is, for example, 20% or more and 60% or less of the diameter of the current collector plate 32.

[0037] The metal plate 40 will be described in detail below with further reference to Figures 3 and 4. Figure 3 is a top view of the metal plate 40, and Figure 4 is an axial cross-sectional view of the metal plate 40. Note that in Figure 3, the area where the metal plate 40 is formed is shown hatched.

[0038] 1, 3, and 4, the metal plate 40 is a member that is disposed between the sealing plate 30 and the current collector plate 32 and sandwiches the positive electrode lead 20 between the sealing plate 30 and the current collector plate 32. Examples of materials for the metal plate 40 include metals containing aluminum as a main component.

[0039] The metal plate 40 has a protrusion 41 provided in the center of the metal plate 40, and a flange 42 provided around the protrusion 41 and in contact with the positive electrode lead 20. The flange 42 is provided so as to surround the entire periphery of the protrusion 41 and has a circular ring shape.

[0040] The convex portion 41 is a portion that bulges upward from the flange portion 42. The convex portion 41 has a top portion 43 that is substantially circular in top view, and a plurality of side portions 44 that connect the top portion 43 to the flange portion 42. In this embodiment, the convex portion 41 has four side portions 44. The top portion 43 is flat and is provided substantially parallel to the flange portion 42. The shape of the top portion 43 is not limited to a substantially circular shape in top view, and may be a substantially rectangular shape in top view.

[0041] Here, the top 43 is joined to the sealing plate 30. More specifically, the top 43 is joined to the underside of the sealing plate 30, in a portion surrounding the protrusion 31. In this embodiment, the top 43 is joined to the sealing plate 30 by laser welding. The number and area of ​​the welds between the top 43 and the sealing plate 30 are set, for example, taking into consideration the joint strength and resistance. Generally, the larger the area of ​​the welds, the higher the joint strength and the lower the resistance. From the perspective of increasing the joint strength between the metal plate 40 and the sealing plate 30, it is preferable that the welds be formed in a circular shape when viewed from above. Note that the method for joining the top 43 and the sealing plate 30 is not limited to laser welding, and they may be joined using an adhesive or the like.

[0042] By joining the top portion 43 of the metal plate 40 to the sealing plate 30, the strength of the central portion of the sealing plate 30 can be increased. This prevents the sealing plate 30 from deforming toward the outside of the battery when, for example, internal pressure increases due to an abnormality in the battery, and a load is applied to the sealing plate 30 pushing it toward the outside of the battery. As a result, it is possible to prevent gas inside the battery from being released from the upper side of the battery (the sealing plate 30 side), improving the safety of the battery.

[0043] Furthermore, by joining the top portion 43 of the metal plate 40 to the sealing plate 30, when a load is applied from the outside of the battery toward the inside of the battery, the sealing plate 30, the current collector plate 32, and the metal plate 40 are prevented from bending and deforming toward the inside of the battery. As a result, it is possible to prevent the occurrence of an internal short circuit caused by the deformed sealing plate 30, the current collector plate 32, and the metal plate 40 coming into contact with the negative electrode 12, and it is possible to ensure battery performance.

[0044] The side portions 44 are pillars that connect the top portion 43 and the flange portion 42. All four side portions 44 have the same shape.

[0045] In this embodiment, the side surface portion 44 extends in a direction inclined with respect to the axial direction. The inclination angle of the extension direction of the side surface portion 44 with respect to the axial direction is, for example, 20° or more and 70° or less, and preferably 30° or more and 60° or less. By setting the inclination angle to 30° or more and 60° or less, bending deformation of the sealing plate 30, the current collecting plate 32, and the metal plate 40 toward the inside of the battery is further suppressed when a load is applied from the outside of the battery toward the inside of the battery. Note that the side surface portion 44 may extend along the axial direction. That is, the side surface portion 44 may be disposed approximately perpendicular to the flange portion 42 and the top portion 43.

[0046] 3 , the four side surface portions 44 are provided at equal angular intervals in the circumferential direction. By providing the side surface portions 44 at equal angular intervals in the circumferential direction, when a load is applied to the metal plate 40 from outside the battery, the load applied to the side surface portions 44 is dispersed, making the side surface portions 44 less likely to deform. As a result, it becomes easier to increase the strength of the central portion of the sealing plate 30, and the effects of the present disclosure are more pronounced.

[0047] Furthermore, side portion 44 is preferably connected to an area of ​​10% or more of the outer periphery of top portion 43, and more preferably connected to an area of ​​15% or more of the outer periphery of top portion 43. In this case, the strength of side portion 44 increases, making it easier to increase the strength of the central portion of sealing plate 30, and the effects of the present disclosure are more significantly exhibited.

[0048] Furthermore, through holes 40A are formed between adjacent side surface portions 44 in the circumferential direction. In other words, four through holes 40A are formed on the sides of the protrusion 41. By providing the through holes 40A, when gas is generated inside the battery in the event of an abnormality and the internal pressure of the battery increases, the gas flows into the space above the metal plate 40 through the through holes 40A. This allows the internal pressure of the battery to be reduced.

[0049] The metal plate 40 does not have to have the through-hole 40A. In other words, the side surface portion 44 of the convex portion 41 may be formed around the entire periphery of the top portion 43. By forming the side surface portion 44 around the entire periphery of the top portion 43, the strength of the metal plate 40 can be further increased.

[0050] The height of the protrusion 41 is not particularly limited as long as the top 43 can be bonded to the sealing plate 30, but is, for example, 0.5 mm or more and 5.0 mm or less.

[0051] The flange portion 42 is provided around the protrusion 41 and is disposed opposite the recess 34 of the current collector plate 32 via the positive electrode lead 20. The flange portion 42 is joined to the positive electrode lead 20 and the metal plate 40, for example, by laser welding in a state in which the positive electrode lead 20 is sandwiched between the flange portion 42 and the recess 34 of the current collector plate 32.

[0052] The size of the flange portion 42 is not particularly limited as long as it is large enough to join the positive electrode lead 20, but is, for example, large enough to cover substantially the entire upper surface of the recess 34 of the current collector plate 32. The radial length of the flange portion 42 is, for example, 30% to 70% of the radius of the metal plate 40.

[0053] Second Embodiment Next, the configuration of a cylindrical battery 10X according to a second embodiment will be described with reference to Figures 5 and 6. Figure 5 is a schematic cross-sectional view of a cylindrical battery 10X, and Figure 6 is a perspective view of an electrode assembly 14 that constitutes the cylindrical battery 10X. Below, the same reference numerals are used to designate components common to the first embodiment, and redundant explanations will be omitted. Differences from the first embodiment will be mainly described.

[0054] As shown in Fig. 5, the cylindrical battery 10X of the second embodiment is the same as the cylindrical battery 10 of the first embodiment in that it includes an electrode assembly 14, a nonaqueous electrolyte (not shown), an outer can 16 that houses the electrode assembly 14 and the nonaqueous electrolyte, a sealing body 17 that closes the opening of the outer can 16, a current collector 32 disposed between the sealing body 17 and the electrode assembly 14, and a metal plate 40 bonded to the upper surface of the current collector 32. On the other hand, as will be described in more detail later, the electrode assembly 14 of the second embodiment differs from the first embodiment in that it does not have a positive electrode lead 20 (see Fig. 1) or a negative electrode lead 21 (see Fig. 1). The cylindrical battery 10X of the second embodiment also differs from the first embodiment in that insulating plates 18, 19 (see Fig. 1) are not disposed above and below the electrode assembly 14.

[0055] 6 , the electrode assembly 14 has a positive electrode 11, a negative electrode 12, and a separator 13, and has a structure in which 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 that constitute the electrode assembly 14 are all long strip-shaped bodies, and are spirally wound so that they are alternately stacked in the radial direction of the electrode assembly 14. The positive electrode 11 protrudes above the negative electrode 12 and the separator 13, and the negative electrode 12 protrudes below the positive electrode 11 and the separator 13.

[0056] The positive electrode 11 has a positive electrode core exposed portion 52 at its upper axial end where the positive electrode mixture layer 51 is not provided and the positive electrode core 50 is exposed. The positive electrode core exposed portion 52 is provided over a range from the winding start end to the winding end end of the long positive electrode 11 in the longitudinal direction. The negative electrode 12 has a negative electrode core exposed portion 62 at its lower axial end where the negative electrode mixture layer 61 is not provided and the negative electrode core 60 is exposed. The negative electrode core exposed portion 62 is provided over a range from the winding start end to the winding end end of the long negative electrode 12 in the longitudinal direction. Therefore, the upper axial end of the electrode body 14 is constituted by the positive electrode core exposed portion 52, and the lower axial end of the electrode body 14 is constituted by the negative electrode core exposed portion 62. The width of the positive electrode substrate exposed portion 52 is, for example, 2 mm or more and 20 mm or less, and the width of the negative electrode substrate exposed portion 62 is, for example, 2 mm or more and 20 mm or less.

[0057] 5, the positive electrode core exposed portion 52 extends from the upper end surface of the electrode body 14 substantially parallel to the axial direction of the electrode body 14. The positive electrode core exposed portion 52 is bent radially inward at the upper end and joined to the lower surface of the flange portion 42 of the metal plate 40. By joining the positive electrode core exposed portion 52 to the metal plate 40, the contact area between the positive electrode core exposed portion 52 and the metal plate 40 increases, and therefore the internal resistance of the positive electrode 11 can be reduced compared to when the positive electrode lead 20 (see FIG. 1) is used.

[0058] 5 , the negative electrode core exposed portion 62 extends from the lower end surface of the electrode body 14 substantially parallel to the axial direction of the electrode body 14. The negative electrode core exposed portion 62 is bent radially inward at the lower end and joined to the inner surface of the bottom 16A of the outer can 16. In this embodiment, the negative electrode core exposed portion 62 is joined to the outer can 16, but similar to the first embodiment, the negative electrode lead 21 may be joined to the inner surface of the bottom 16A of the outer can 16. In other words, the electrode body 14 may not have a positive electrode lead 20 and may have only the negative electrode lead 21.

[0059] Similar to the first embodiment, the metal plate 40 of the second embodiment has a protrusion 41 in the center. The protrusion 41 has a top 43 and a side surface 44, and the top 43 is joined to the sealing plate 30. Even when the positive electrode substrate exposed portion 52 is joined to the underside of the metal plate 40, the strength of the central portion of the sealing plate 30 can be increased by joining the top 43 of the metal plate 40 to the sealing plate 30.

[0060] As described above, by disposing metal plate 40 having protrusions 41 between sealing body 17 and current collector plate 32 and joining tops 43 of protrusions 41 to sealing body 17, the strength of the central portion of sealing plate 30 can be increased. This prevents sealing plate 30 from deforming outward from the battery when, for example, internal pressure increases during a battery abnormality, causing a load to be applied to sealing plate 30 pushing it outward from the battery. Furthermore, when a load is applied from the outside of the battery toward the inside of the battery, sealing plate 30, current collector plate 32, and metal plate 40 are prevented from bending and deforming toward the inside of the battery. As a result, battery performance and safety can be ensured.

[0061] The above embodiment can be modified as appropriate without impairing the objectives of the present disclosure. For example, as shown in FIG. 7 , a thin-walled portion 45 formed with a recessed underside may be provided on the side surface 44 of the metal plate 40. The thin-walled portion 45 functions as a deformable portion that deforms preferentially when the cylindrical battery 10 is pressed from the radial outside toward the radial inside. By providing the thin-walled portion 45 on the underside of the side surface 44, when the cylindrical battery 10 is pressed from the radial outside toward the radial inside, the side surface 44 deforms by bending upward from the thin-walled portion 45. In other words, providing the thin-walled portion 45 on the lower surface of the side surface 44 prevents the metal plate 40 from deforming downward when the cylindrical battery 10 is pressed from the radial outside toward the radial inside. This prevents the metal plate 40 from contacting the negative electrode 12, thereby ensuring battery performance.

[0062] The thin-walled portion 45 is formed, for example, along the circumferential direction. The number of thin-walled portions 45 provided on the side surface portion 44 may be one, or may be two or more. Note that, when the metal plate 40 has a plurality of side surface portions 44, it is preferable that the thin-walled portions 45 be provided on all of the side surface portions 44.

[0063] The size, shape, etc. of the thin-walled portion 45 are not particularly limited as long as it can function as the easily deformable portion. In the example shown in Fig. 7, the thin-walled portion 45 is formed by forming a V-shaped groove 46 on the lower surface of the side surface portion 44. The minimum thickness of the thin-walled portion 45 is, for example, 30% to 70% of the thickness of the portion of the side surface portion 44 other than the thin-walled portion 45.

[0064] 8 , the side surface portion 44 of the metal plate 40 may have a bent shape. By having the bent side surface portion 44, when the cylindrical battery 10 is pressed from the radial outside toward the radial inside, the side surface portion 44 is deformed so as to fold starting from the bent portion. In other words, by having the bent side surface portion 44, when the cylindrical battery 10 is pressed from the radial outside toward the radial inside, downward deformation of the metal plate 40 is suppressed. This makes it possible to suppress the occurrence of an internal short circuit due to the metal plate 40 coming into contact with the negative electrode 12, thereby ensuring battery performance.

[0065] Furthermore, in the above embodiment, the case where the first electrode is the positive electrode 11 and the second electrode is the negative electrode 12 has been described, but the first electrode may be the negative electrode 12 and the second electrode may be the positive electrode 11. That is, in the first embodiment, the negative electrode lead 21 extending from the negative electrode 12 may be joined to the current collector plate 32, and the positive electrode lead 20 extending from the positive electrode 11 may be joined to the outer casing can 16. Furthermore, in the second embodiment, the negative electrode 12 may protrude upward beyond the positive electrode 11 and the separator 13, and the positive electrode 11 may protrude downward beyond the negative electrode 12 and the separator 13.

[0066] Furthermore, in the above embodiment, the tops 43 of the convex portions 41 of the metal plate 40 are flat, but the tops 43 may have an uneven shape. Furthermore, as shown in Fig. 9, the convex portions 41 of the metal plate 40 may have a plurality of steps. Furthermore, in addition to the tops 43 of the convex portions 41 being joined to the underside of the sealing plate 30, the side surfaces 44 of the convex portions 41 may abut against the inner surfaces of the convex portions 31 of the sealing plate 30. With the above configuration, when the internal pressure of the battery increases, the space through which gas flows increases, thereby further reducing the internal pressure of the battery.

[0067] The present disclosure is further described by the following embodiments. Configuration 1: A cylindrical battery comprising: an electrode assembly in which a first electrode and a second electrode are wound with a separator interposed therebetween; a bottomed cylindrical outer can housing the electrode assembly; a sealing body closing the opening of the outer can; a current collector plate disposed between the sealing body and the electrode assembly; and a metal plate joined to the surface of the current collector plate facing the sealing body, wherein the metal plate has a top and side portions, a convex portion provided in the center of the metal plate, and a flange portion provided around the convex portion, and the top is joined to the sealing body. Configuration 2: The cylindrical battery according to Configuration 1, wherein the electrode assembly has an electrode lead connected to the first electrode, and the electrode lead is sandwiched between the current collector plate and the metal plate. Configuration 3: The cylindrical battery according to Configuration 1, wherein the first electrode has a first electrode core and a first electrode mixture layer formed on the surface of the first electrode core, and a first electrode core exposed portion where the first electrode core is exposed is provided at the end of the electrode body facing the sealing body, and the first electrode core exposed portion is joined to the surface of the current collector plate facing the electrode body.Configuration 4: The cylindrical battery according to any one of Configurations 1 to 3, wherein the convex portion has a through hole.Configuration 5: The cylindrical battery according to any one of Configurations 1 to 4, wherein the convex portion has a plurality of side portions, and the side portions are provided at equal angular intervals from each other in the circumferential direction.Configuration 6: The cylindrical battery according to any one of Configurations 1 to 5, wherein the side portions extend in a direction inclined with respect to the axial direction of the outer can, and the inclination angle of the extension direction of the side portions with respect to the axial direction of the outer can is 30° or more and 60° or less. Configuration 7: The cylindrical battery according to any one of Configurations 1 to 6, wherein a peripheral edge portion provided on the outer periphery of the current collector plate is joined to the sealing member.Configuration 8: The cylindrical battery according to any one of Configurations 1 to 7, wherein the current collector plate is fixed to the opening of the outer can by crimping.Configuration 9: The cylindrical battery according to any one of Configurations 1 to 8, wherein the protrusion has a plurality of steps.Configuration 10: The cylindrical battery according to any one of Configurations 1 to 9, wherein at least a portion of the side surface portion abuts against the sealing member.

[0068] 10, 10X Cylindrical battery (battery), 11 Positive electrode (first electrode), 12 Negative electrode (second electrode), 13 Separator, 14 Electrode body, 16 Outer can, 16A Bottom, 17 Sealing body, 18 Insulating plate, 18A Through hole, 19 Insulating plate, 20 Positive electrode lead, 21 Negative electrode lead, 22 Grooved portion, 23 Groove, 24 Gasket, 30 Sealing plate, 31 Convex portion, 32 Current collector plate, 32A Through hole, 33 Peripheral portion, 34 Concave portion, 40 Metal plate, 41 Convex portion, 42 Flange portion, 43 Top portion, 44 Side portion, 45 Thin portion, 46 Groove, 50 Positive electrode core, 51 Positive electrode mixture layer, 52 Positive electrode core exposed portion, 60 Negative electrode core, 61 Negative electrode mixture layer, 62 Negative electrode core exposed part

Claims

1. A cylindrical battery comprising: an electrode assembly in which a first electrode and a second electrode are wound with a separator between them; a bottomed cylindrical outer can containing the electrode assembly; a seal body that closes the opening of the outer can; a current collector plate arranged between the seal body and the electrode assembly; and a metal plate joined to the surface of the current collector plate facing the seal body, wherein the metal plate has a top and side portions, and has a convex portion provided in the center of the metal plate and a flange portion provided around the convex portion, and the top is joined to the seal body.

2. The cylindrical battery according to claim 1, wherein the electrode body has an electrode lead connected to the first electrode, the electrode lead being sandwiched between the current collector plate and the metal plate.

3. The cylindrical battery described in claim 1, wherein the first electrode has a first electrode core and a first electrode mixture layer formed on a surface of the first electrode core, a first electrode core exposed portion where the first electrode core is exposed is provided at an end of the electrode body facing the sealing body, and the first electrode core exposed portion is joined to the surface of the current collector facing the electrode body.

4. The cylindrical battery according to claim 1, wherein the protrusion has a through hole.

5. The cylindrical battery according to claim 1, wherein the protrusion has a plurality of side surfaces, the side surfaces being arranged at equal angular intervals from one another in the circumferential direction.

6. The cylindrical battery as described in claim 1, wherein the side surface portion extends in a direction inclined with respect to the axial direction of the outer can, and the inclination angle of the extension direction of the side surface portion with respect to the axial direction of the outer can is 30° or more and 60° or less.

7. The cylindrical battery according to claim 1, wherein a peripheral portion provided on the outer periphery of the current collector plate is joined to the sealing body.

8. The cylindrical battery according to claim 1, wherein the current collector plate is fixed to the opening of the outer can by crimping.

9. The cylindrical battery according to claim 1, wherein the protruding portion has a plurality of steps.

10. The cylindrical battery according to claim 1, wherein at least a portion of the side surface abuts against the sealing body.

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