Cylindrical battery

Abstract

This cylindrical battery (10) is characterized by comprising: an electrode body (14); a bottomed cylindrical outer can (16) that accommodates the electrode body 14; a sealing body (17) that closes the opening of the outer can (16); and a current collector plate (40) that is disposed between the sealing body (17) and the electrode body (14) and has a through-hole (30A), the cylindrical battery (10) including a positive electrode lead (20) connected to the positive electrode (11). The positive electrode lead (20) is joined to the lower surface of the current collector plate (40). The current collector plate (40) has a top part (45) and a plurality of side surface parts (46), has a protruding part (41) provided in the central part of the current collecting plate (40), and has an annular recessed part (42) provided around the protruding part (41). The top part (45) is joined 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 comprises 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 sealing can, and a current collector plate that is arranged between the sealing body and the electrode assembly and has a through hole, and is a cylindrical battery including an electrode lead connected to the first electrode, wherein the electrode lead extends through the through hole toward the sealing body and is joined to the surface of the current collector plate facing the sealing body, and the current collector plate has a top and multiple side surfaces, a convex portion provided in the center of the current collector plate, and an annular concave portion provided around the convex portion, and the top is joined to the sealing body.

[0007] Furthermore, another 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 bottomed cylindrical outer can that houses the electrode assembly, a sealing body that closes the opening of the outer can, and a current collector plate that is arranged between the sealing body and the electrode assembly, 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 that exposes the first electrode core is provided at the end of the electrode assembly facing the sealing body, and the first electrode core exposed portion is joined to the surface of the current collector plate facing the electrode assembly, the current collector plate has a top and side portions, and has a convex portion provided in the center of the current collector plate and a concave portion provided around the convex portion to which the first electrode core exposed portion is joined, and the top is joined to the sealing body.

[0008] 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.

[0009] 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 a diagram showing a modified current collector plate constituting the cylindrical battery of the first embodiment. FIG. 6 is a diagram showing a modified current collector plate constituting the cylindrical battery of the first embodiment, showing a state in which the current collector plate is pressed from the radially outer side. FIG. 7 is a diagram showing a modified current collector plate constituting the cylindrical battery of the first embodiment. FIG. 8 is an axial cross-sectional view of a cylindrical battery of the second embodiment. FIG. 9 is a perspective view of an electrode body constituting the cylindrical battery of the second embodiment. FIG. 10 is an axial cross-sectional view of a cylindrical battery of the third embodiment. FIG. 11 is a diagram showing a modified cylindrical battery.

[0010] 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.

[0011] [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.

[0012] 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 the electrode assembly 14 and the nonaqueous electrolyte, a sealing body 17 that closes the opening of the outer can 16, and a current collector plate 40 disposed between the sealing body 17 and the electrode assembly 14. In this specification, the sealing body 17 side of cylindrical battery 10 is referred to as the "top" and the bottom 16A side of the outer can 16 is referred to as the "bottom." In the following, a case in which the first electrode is a positive electrode 11 and the second electrode is a negative electrode 112 will be described.

[0013] 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.

[0014] 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.

[0015] 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.

[0016] 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.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] The non-aqueous electrolyte has lithium ion conductivity and may be a liquid electrolyte (electrolytic solution) or a solid electrolyte.

[0024] 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

[0025] 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.

[0026] 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 40A (see FIG. 3 ) provided in the current collector 40. The positive electrode lead 20 is bent to fit along the upper surface of a recess 42 of the current collector 40 (described below) and joined to the upper surface of the recess 42 of the current collector 40 by welding or the like. Joining the positive electrode lead 20 to the upper surface of the current collector 40 not only prevents the positive electrode lead 20 from coming off the surface of the current collector 40 but also improves the workability of welding the positive electrode lead 20 to the current collector 40. As will be described in more detail below, the current collector 40 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.

[0027] 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.

[0028] 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 40. 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 40 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 40 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] The sealing plate 30 has a central protrusion 31 that protrudes toward the outside of the battery. 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 current collector plate 40 near the central portion of the sealing plate 30. Therefore, the diameter of the protrusion 31 on the sealing plate 30 is configured to be smaller than the diameter of the apex 45 on the current collector 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.

[0033] 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.

[0034] The current collector plate 40 will be described in detail below with further reference to Figures 3 and 4. Figure 3 is a top view of the current collector plate 40, and Figure 4 is an axial cross-sectional view of the current collector plate 40. In Figure 3, the area where the current collector plate 40 is formed is shown hatched.

[0035] 1 , 3 , and 4 , the current collector 40 is a member to which the positive electrode lead 20 is joined, and is disposed between the sealing body 17 and the electrode body 14. Examples of materials for the current collector 40 include metals containing aluminum as a main component. Similar to the sealing plate 30, the current collector 40 is fixed to the opening of the outer can 16 by crimping via a gasket 24.

[0036] The current collector plate 40 has a protrusion 41 provided in the center of the current collector plate 40, a recess 42 provided around the protrusion 41 and to which the positive electrode lead 20 is joined, and a peripheral edge 43 provided radially outward from the recess 42 and in contact with the lower surface of the sealing plate 30. The recess 42 and the peripheral edge 43 are each formed in an annular shape. A step 44 is provided between the recess 42 and the peripheral edge 43, and the recess 42 has a shape that is recessed downward from the peripheral edge 43.

[0037] The convex portion 41 is a portion that bulges upward from the concave portion 42. The convex portion 41 has a top portion 45 that is substantially circular in top view, and a plurality of side portions 46 that connect the top portion 45 and the concave portion 42. In this embodiment, the convex portion 41 has four side portions 46. The top portion 45 is flat and is provided substantially parallel to the concave portion 42. Note that the shape of the top portion 45 is not limited to a substantially circular shape in top view, and may be a substantially rectangular shape in top view.

[0038] Here, the top 45 is joined to the sealing plate 30. More specifically, the top 45 is joined to the underside of the sealing plate 30, in a portion surrounding the protrusion 31. In this embodiment, the top 45 is joined to the sealing plate 30 by laser welding. The number and area of ​​the welds between the top 45 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 current collecting 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 45 and the sealing plate 30 is not limited to laser welding, and they may be joined using an adhesive or the like.

[0039] By joining the top portion 45 of the current collector 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.

[0040] Furthermore, by joining the top portion 45 of the current collector 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 and the current collector 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 and the current collector plate 40 coming into contact with the negative electrode 12, and battery performance can be ensured.

[0041] The side portions 46 are pillars that connect the top portion 45 and the recessed portion 42. All four side portions 46 have the same shape.

[0042] In this embodiment, the side surface portion 46 extends in a direction inclined with respect to the axial direction. The inclination angle of the extension direction of the side surface portion 46 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 and the current collector 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 46 may extend along the axial direction. That is, the side surface portion 46 may be provided approximately perpendicular to the recess 42 and the top portion 45.

[0043] 3 , the four side surface portions 46 are provided at equal angular intervals in the circumferential direction. By providing the side surface portions 46 at equal angular intervals in the circumferential direction, when a load is applied to the current collector plate 40 from outside the battery, the load applied to the side surface portions 46 is dispersed, making the side surface portions 46 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.

[0044] The number of side surface portions 46 is preferably four or more. Furthermore, side surface portions 46 are preferably connected to an area of ​​10% or more of the outer periphery of top portion 45, and more preferably connected to an area of ​​15% or more of the outer periphery of top portion 45. In this case, the strength of side surface portions 46 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.

[0045] Furthermore, a through hole 40A is formed between adjacent side surface portions 46 in the circumferential direction. That is, four through holes 40A are formed on the sides of the protrusion 41. As described above, the through holes 40A are holes through which the positive electrode leads 20 pass. In this embodiment, the four side surface portions 46 have the same shape and are provided at equal angular intervals in the circumferential direction, and therefore the shapes of all four through holes 40A are the same. The number, arrangement, size, etc. of the through holes 40A can be set appropriately according to the number, shape, etc. of the positive electrode leads 20.

[0046] The height of the protrusion 41 is not particularly limited as long as the top 45 can be bonded to the sealing plate 30, but is, for example, 0.5 mm or more and 5.0 mm or less.

[0047] The recess 42 is provided around the protrusion 41, and the positive electrode lead 20 is joined thereto. The method for joining the positive electrode lead 20 is not particularly limited, and examples thereof include laser welding. The recess 42 has a substantially uniform radial length along the circumferential direction. The size of the recess 42 is not particularly limited as long as it is large enough to join the positive electrode lead 20 thereto. For example, the radial length of the recess 42 is 10% or more and 30% or less of the radius of the current collector plate 40.

[0048] The peripheral edge 43 is provided radially outward of the recess 42 and abuts against the underside of the sealing plate 30. The peripheral edge 43 is joined to the sealing plate 30 by laser welding. The number and area of ​​the welds between the peripheral edge 43 and the sealing plate 30 are set, for example, taking into consideration the joint strength and resistance. The peripheral edge 43 is crimped and fixed to the opening of the outer can 16 via the gasket 24. By crimping and fixing the peripheral edge 43 to the opening of the outer can 16, the current collecting plate 40 can be firmly fixed to the top of the outer can 16.

[0049] Next, an example of a modified current collector plate 40 will be described with reference to Figures 5 and 6. Figure 5 is an axial cross-sectional view of the current collector plate 40, and Figure 6 is a diagram showing the deformation of the current collector plate 40 when a cylindrical battery 10 is pressed radially inward from the outside.

[0050] The side surface portion 46 of the current collecting plate 40 shown in Fig. 5 has a thin portion 47 formed so that the lower surface is recessed. The thin portion 47 is formed along the circumferential direction. The number of thin portions 47 provided on the side surface portion 46 may be one, or may be two or more. Note that, when the current collecting plate 40 has multiple side surface portions 46, it is preferable that the thin portion 47 be provided on all of the side surface portions 46.

[0051] As shown in Figure 6, the thin-walled portion 47 functions as a deformable portion that deforms preferentially when the cylindrical battery 10 is pressed radially inward from the outside. By providing the thin-walled portion 47 on the underside of the side surface portion 46, when the cylindrical battery 10 is pressed radially inward from the outside, the side surface portion 46 deforms by bending upward from the thin-walled portion 47. In other words, providing the thin-walled portion 47 on the underside of the side surface portion 46 prevents the current collector plate 40 from deforming downward when the cylindrical battery 10 is pressed radially inward from the outside. This prevents the current collector plate 40 from contacting the negative electrode 12, thereby ensuring battery performance.

[0052] The size, shape, etc. of the thin-walled portion 47 are not particularly limited as long as it can function as the easily deformable portion. In the example shown in Fig. 5, the thin-walled portion 47 is formed by forming a V-shaped groove 48 on the lower surface of the side surface portion 46. The minimum thickness of the thin-walled portion 47 is, for example, 30% to 70% of the thickness of the portion of the side surface portion 46 other than the thin-walled portion 47.

[0053] Next, another example of a modified current collector plate 40 will be described with reference to Fig. 7. Fig. 7 is an axial cross-sectional view of the current collector plate 40.

[0054] The side surface portion 46 of the current collector plate 40 shown in Figure 7 has a bent shape. Because the side surface portion 46 has a bent shape, when the cylindrical battery 10 is pressed from the radial outside toward the radial inside, the side surface portion 46 deforms so as to fold starting from the bent point. In other words, because the side surface portion 46 has a bent shape, when the cylindrical battery 10 is pressed from the radial outside toward the radial inside, the current collector plate 40 is prevented from deforming downward. This makes it possible to prevent the current collector plate 40 from contacting the negative electrode 12 and ensure battery performance.

[0055] Second Embodiment Next, the configuration of a cylindrical battery 10X according to a second embodiment will be described with reference to Figures 8 and 9. Figure 8 is a schematic cross-sectional view of a cylindrical battery 10X, and Figure 9 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.

[0056] As shown in Fig. 8 , 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, and a current collector plate 40 disposed between the sealing body 17 and the electrode assembly 14. 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.

[0057] 9 , 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.

[0058] 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.

[0059] 8, the positive electrode substrate 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 substrate exposed portion 52 is bent radially inward at the upper end and joined to the lower surface of the recess 42 of the current collector plate 40. By joining the positive electrode substrate exposed portion 52 to the current collector plate 40, the contact area between the positive electrode substrate exposed portion 52 and the current collector 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.

[0060] 8 , 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.

[0061] Similar to the first embodiment, the current collector plate 40 of the second embodiment has a protrusion 41 in its central portion. The protrusion 41 has a top portion 45 and a side portion 46, and the top portion 45 is joined to the sealing plate 30. Even when the positive electrode substrate exposed portion 52 is joined to the underside of the current collector plate 40, the strength of the central portion of the sealing plate 30 can be increased by joining the top portion 45 of the current collector plate 40 to the sealing plate 30.

[0062] As described above, the electrode body 14 of the second embodiment does not have a positive electrode lead 20 (see FIG. 1 ). Therefore, the current collector plate 40 does not need to have a through-hole 40A. In other words, the side surface portion 46 of the convex portion 41 may be formed around the entire periphery of the top portion 45. By forming the side surface portion 46 around the entire periphery of the top portion 45, the strength of the current collector plate 40 is further increased, and the effects of the present disclosure are more significantly exhibited.

[0063] It should be noted that the current collector plate 40 of the second embodiment may also be provided with a through hole 40A. That is, the protrusion 41 may have a plurality of side surfaces 46. By providing the through hole 40A in the current collector plate 40, 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 current collector plate 40 through the through hole 40A. This allows the internal pressure of the battery to be reduced.

[0064] Third Embodiment Next, the configuration of a cylindrical battery 10Y according to a third embodiment will be described with reference to Fig. 10. Fig. 10 is a schematic cross-sectional view of a cylindrical battery 10Y. Below, the same reference numerals will be used to designate components common to the first embodiment, and redundant explanations will be omitted. Differences from the first embodiment will be mainly described.

[0065] 10 , the cylindrical battery 10Y of the third 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 accommodates the electrode assembly 14 and the nonaqueous electrolyte, a sealing body 17 that closes the opening of the outer can 16, and a current collector plate 40 disposed between the sealing body 17 and the electrode assembly 14. Similarly to the cylindrical battery 10 of the first embodiment, the cylindrical battery 10Y of the third embodiment also includes a positive electrode lead 20 and a negative electrode lead 21. Alternatively, the cylindrical battery 10Y may not include the negative electrode lead 21, and the exposed portion of the negative electrode core may be joined to the inner surface of the bottom 16A of the outer can 16, similar to the cylindrical battery 10X of the second embodiment.

[0066] As shown in FIG. 10 , the cylindrical battery 10 has a metal plate 32 disposed between the current collector 40 and the sealing plate 30. The metal plate 32 has an opening 32A in the center and is ring-shaped. The metal plate 32 is disposed opposite the recess 42 of the current collector 40 with the positive electrode lead 20 interposed therebetween. In other words, the positive electrode lead 20 is sandwiched between the current collector 40 and the metal plate 32. By sandwiching the positive electrode lead 20 between the current collector 40 and the metal plate 32, the positive electrode lead 20 is less likely to come off the current collector 40. The positive electrode lead 20 can be joined by laser welding while sandwiched between the current collector 40 and the metal plate 32.

[0067] In the above embodiments, the first electrode is the positive electrode 11 and the second electrode is the negative electrode 12. However, the first electrode may be the negative electrode 12 and the second electrode may be the positive electrode 11. That is, in the first and third embodiments, the negative electrode lead 21 extending from the negative electrode 12 may be joined to the current collector 40, and the positive electrode lead 20 extending from the positive electrode 11 may be joined to the outer casing 16. 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.

[0068] Furthermore, in each of the above-described embodiments, the tops 45 of the convex portions 41 of the current collecting plate 40 are flat, but the tops 45 may have an uneven shape. Furthermore, as shown in FIG. 11 , the convex portions 41 of the current collecting plate 40 may have a plurality of steps. Furthermore, in addition to the tops 45 of the convex portions 41 being joined to the underside of the sealing plate 30, at least a portion of the side surfaces 46 of the convex portions 41 may abut against the inner surfaces of the convex portions 31 of the sealing plate 30. With the above-described 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.

[0069] The present disclosure will be 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 cylindrical outer can with a bottom that houses the electrode assembly; a seal that closes the opening of the seal; and a current collector plate that is disposed between the seal and the electrode assembly and has a through hole, the cylindrical battery including an electrode lead connected to the first electrode, the electrode lead extending toward the seal through the through hole and joined to the surface of the current collector plate facing the seal, the current collector plate having a top and multiple side surfaces, a protrusion provided in a central portion of the current collector plate and an annular recess provided around the protrusion, the top being joined to the seal. Configuration 2: 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 that houses the electrode assembly; a sealing body that closes the opening of the outer can; and a current collector plate that is arranged between the sealing body and the electrode assembly, wherein the first electrode has a first electrode core and a first electrode mixture layer formed on the surface of the first electrode core, a first electrode core exposed portion where the first electrode core is exposed is provided at the end of the electrode assembly facing the sealing body, and the first electrode core exposed portion is joined to the surface of the current collector plate facing the electrode assembly, the current collector plate has a top and side portions, and has a convex portion provided in the center of the current collector plate and a ring-shaped concave portion provided around the convex portion, and the top is joined to the sealing body. Configuration 3: The cylindrical battery according to Configuration 1 or 2, wherein the protrusion has a plurality of the side surface portions, and the side surface portions are arranged at equal angular intervals in the circumferential direction.Configuration 4: The cylindrical battery according to any one of Configurations 1 to 3, wherein the side surface 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 surface portions with respect to the axial direction of the outer can is 30° or more and 60° or less.Configuration 5: The cylindrical battery according to any one of Configurations 1 to 4, wherein a peripheral edge portion provided on the outer periphery of the current collector plate is joined to the sealing body.Configuration 6: The cylindrical battery according to any one of Configurations 1 to 5, wherein the side surface portions have thin-walled portions formed so that the surfaces of the side surface portions facing the electrode body are recessed.Configuration 7: The cylindrical battery according to any one of Configurations 1 to 6, wherein the side surface portions have a curved shape.Configuration 8: The cylindrical battery according to any one of Configurations 1 to 7, further comprising a metal plate disposed between the current collector and the sealing member and having an opening in its center, the electrode lead being sandwiched between the current collector and the metal plate.Configuration 9: The cylindrical battery according to any one of Configurations 1 to 8, wherein the current collector is fixed to the opening of the outer can by crimping.Configuration 10: The cylindrical battery according to any one of Configurations 1 to 9, wherein the protrusion has a plurality of steps.Configuration 11: The cylindrical battery according to any one of Configurations 1 to 10, wherein at least a portion of the side surface abuts against the sealing member.

[0070] 10, 10X, 10Y 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 Metal plate, 32A Opening, 40 Current collector plate, 40A Through hole, 41 Convex portion, 42 Concave portion, 43 Peripheral portion, 44 Step, 45 Top, 46 Side portion, 47 Thin portion, 48 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 substrate exposed portion

Claims

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 cylindrical outer can with a bottom that houses the electrode assembly; a seal that closes the opening of the seal can; and a current collector plate arranged between the seal and the electrode assembly and having a through hole, the cylindrical battery including an electrode lead connected to the first electrode, wherein the electrode lead extends through the through hole towards the seal and is joined to the surface of the current collector plate facing the seal, the current collector plate having a top and side portions, and having a convex portion provided in the center of the current collector plate and an annular concave portion provided around the convex portion, the top being joined to the seal.

2. A cylindrical battery comprising: an electrode body in which a first electrode and a second electrode are wound with a separator interposed therebetween; a bottomed cylindrical outer can containing the electrode body; a sealing body that closes the opening of the outer can; and a current collector plate arranged between the sealing body and the electrode body, wherein the first electrode has a first electrode core and a first electrode mixture layer formed on the surface of the first electrode core, a first electrode core exposed portion at which 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 plate facing the electrode body, and the current collector plate has a top and side portions, and has a convex portion provided in the center of the current collector plate and an annular concave portion provided around the convex portion, and the top is joined to the sealing body.

3. A cylindrical battery as claimed in claim 1 or 2, 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.

4. A cylindrical battery as described in claim 1 or 2, wherein the side portion extends in a direction inclined with respect to the axial direction of the outer casing, and the inclination angle of the extension direction of the side portion with respect to the axial direction of the outer casing is 30° or more and 60° or less.

5. The cylindrical battery according to claim 1 or 2, wherein a peripheral portion provided on the outer periphery of the current collector plate is joined to the sealing body.

6. A cylindrical battery as claimed in claim 1 or 2, wherein the side surface has a thin-walled portion formed so that the surface of the side surface facing the electrode body is recessed.

7. The cylindrical battery according to claim 1 or 2, wherein the side portion has a curved shape.

8. The cylindrical battery according to claim 1, further comprising a metal plate disposed between the current collector and the sealing body and having an opening in the center, wherein the electrode lead is sandwiched between the current collector and the metal plate.

9. The cylindrical battery according to claim 1 or 2, wherein the current collector plate is fixed to the opening of the outer casing by crimping.

10. The cylindrical battery according to claim 1 or 2, wherein the protruding portion has a plurality of steps.

11. The cylindrical battery according to claim 1 or 2, wherein at least a portion of the side surface abuts against the sealing body.

Images