WO2025115592A1 - Cylindrical battery - Google Patents

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

This disclosure relates to cylindrical batteries.

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

International Publication No. 2023/281973

In a cylindrical battery, 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 heat up abnormally. This may result in gas being generated 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 will be ejected from the sealing body side, which may be undesirable from the perspective of ensuring the safety of the battery.

In addition, when a load is applied from the outside of the battery toward the inside of the battery, the sealing body or current collector plate may bend and deform toward the inside of the battery. If the sealing body or current collector plate bends and deforms toward the inside of the battery, the sealing body or current collector plate may come into contact with the electrode plate of the electrode body, causing an internal short circuit and impairing battery performance. Furthermore, when an internal short circuit occurs, as with the external short circuit described above, a large current may be applied to the electrode body, causing the electrode body to heat up abnormally.

The 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, the metal plate having 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.

The cylindrical battery according to one aspect of the present disclosure can suppress deformation of the sealing body and current collector plate. As a result, the battery performance and safety of the cylindrical battery can be ensured.

FIG. 2 is an axial cross-sectional view of a cylindrical battery according to the first embodiment. FIG. 2 is a perspective view of an electrode body that constitutes the cylindrical battery of the first embodiment. FIG. 2 is a top view of a current collector plate constituting the cylindrical battery of the first embodiment. 2 is an axial cross-sectional view of a current collector plate constituting a cylindrical battery according to the first embodiment. FIG. FIG. 6 is an axial cross-sectional view of a cylindrical battery according to a second embodiment. FIG. 11 is a perspective view of an electrode body that constitutes a cylindrical battery according to a second embodiment. 13A and 13B are diagrams showing modified examples of current collector plates constituting a cylindrical battery. 13A and 13B are diagrams showing modified examples of current collector plates constituting a cylindrical battery. FIG. 13 is a diagram showing a modified example of a cylindrical battery.

Below, 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. In addition, forms formed by selectively combining the components of the embodiments described below are included in the present disclosure.

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

1 and 2, the cylindrical battery 10 comprises an electrode assembly 14 in which a first electrode and a second electrode are wound with a separator therebetween, a non-aqueous electrolyte (not shown), an outer can 16 that contains the electrode assembly 14 and the non-aqueous electrolyte, a sealing body 17 that closes the opening of the outer can 16, a current collector 32 that is disposed between the sealing body 17 and the electrode assembly 14, and a metal plate 40 that is bonded to the upper surface of the current collector 32. In this specification, the sealing body 17 side of the 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.

The electrode body 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 wound in a spiral shape with the separator 13 interposed therebetween. The positive electrode 11, the negative electrode 12, and the separator 13 constituting the electrode body 14 are all long strip-shaped bodies, and are alternately stacked in the radial direction of the electrode body 14 by being wound in a spiral shape. The negative electrode 12 is formed with dimensions slightly larger than the positive electrode 11 to prevent lithium precipitation. In other words, the negative electrode 12 is formed longer in the longitudinal direction and width direction than the positive electrode 11. The separator 13 is formed with dimensions 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.

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 multiple 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 multiple.

The positive electrode 11 has a positive electrode core and a positive electrode mixture layer formed on the positive electrode core. For the positive electrode core, a foil of a metal that is stable in the potential range of the positive electrode 11, such as aluminum or an aluminum alloy, or a film with the metal disposed on the surface layer can be used. The positive electrode mixture layer contains a positive electrode active material, a conductive agent, and a binder, and is preferably formed on both sides of the positive electrode core except for the exposed portion of the positive electrode core (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, and a binder onto 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.

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 elements constituting the lithium metal composite oxide are, 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. An example of a suitable composite oxide is a lithium metal composite oxide containing Ni, Co, and Mn, or a lithium metal composite oxide containing Ni, Co, and Al.

Examples of the conductive agent 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 the binder 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 carboxymethylcellulose (CMC) or a salt thereof, polyethylene oxide (PEO), and the like.

The negative electrode 12 has a negative electrode core and a negative electrode mixture layer formed on the negative electrode core. For the negative electrode core, a foil of a metal that is stable in the potential range of the negative electrode 12, such as copper or a copper alloy, or a film with the metal disposed on the surface layer can be used. 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, etc., 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.

The negative electrode mixture layer generally contains, as the negative electrode active material, a carbon material that reversibly absorbs and releases lithium ions. A suitable example of the carbon material is graphite, such as natural graphite, such as flake graphite, lump graphite, and earthy graphite, and artificial graphite, such as lump artificial graphite (MAG) and graphitized mesophase carbon microbeads (MCMB). In addition, 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 said element, may be used. Among these, a composite material containing Si is preferred.

A suitable example of the composite material containing Si is a material in which Si particles are dispersed in a _SiO2 phase or a silicate phase such as lithium silicate, or a material in which Si 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. It is preferable to use a carbon material and a Si-containing composite material together as the negative electrode active material from the viewpoint of achieving both high capacity and high durability of the battery.

As with the positive electrode mixture layer, the binder contained in the negative electrode mixture layer can be fluorine-containing resin, PAN, polyimide, acrylic resin, polyolefin, etc., 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), etc. Among these, it is preferable to use SBR in combination with CMC or a salt thereof, PAA or a salt thereof, etc. The negative electrode mixture layer may contain a conductive agent such as CNT.

For the separator 13, a porous sheet having ion permeability and insulating properties is used. 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 on the interface between the separator 13 and at least one of the positive electrode 11 and the negative electrode 12.

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

The liquid electrolyte (electrolytic solution) includes a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. For example, esters, ethers, nitriles, amides, and mixed solvents of two or more of these are used as the non-aqueous solvent. 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 product (e.g., fluoroethylene carbonate, etc.) in which at least a part of the hydrogen of these solvents is replaced with a halogen atom such as fluorine. For example, a lithium salt such as _LiPF6 is used as the electrolyte salt.

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 a 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.

Insulating plates 18 and 19 are arranged above and below the electrode body 14. The positive electrode lead 20 extends to the sealing body 17 side through a through hole 18A provided in the insulating plate 18 and a through hole 32A provided in the current collector plate 32. The positive electrode lead 20 is bent so as to follow the upper surface of the recess 34 of the current collector plate 32, and is joined by welding or the like so as to be sandwiched between the current collector plate 32 and the metal plate 40. By sandwiching the positive electrode lead 20 between the current collector plate 32 and the metal plate 40, the positive electrode lead 20 is less likely to come off the surface of the current collector plate 32, and the workability when welding the positive electrode lead 20 can be improved. As will be described in detail later, the current collector plate 32 and the sealing body 17 are electrically connected. Therefore, the sealing body 17 becomes the positive electrode terminal. In this embodiment, the negative electrode lead 21 extends to the bottom 16A side 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.

The outer can 16 is a cylindrical metal container with a bottom that is open on one axial side. The opening of the outer can 16 is sealed 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. Furthermore, by providing the gasket 24, insulation between the outer can 16 and the sealing body 17 is ensured. 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.

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

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 of the electrode body 14, etc., gas is released from the gas exhaust port provided in the bottom 16A of the exterior can 16.

For example, a ring-shaped groove 23 is formed in the bottom 16A of the exterior can 16, and the portion surrounded by the groove 23 becomes the gas exhaust port. The groove 23 may be C-shaped when viewed from the bottom, but from the viewpoint of improving breakability when the internal pressure increases, it is preferable that it is formed in a perfect circle when viewed from the bottom. The groove 23 is, for example, an imprint formed on the outer surface side of the bottom 16A.

As described above, the sealing body 17 has the function of sealing 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 sealing 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 the top of the sealing plate 30.

The sealing plate 30 has a convex portion 31 at its center that protrudes toward the outside of the battery. The convex portion 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 its center. Therefore, the diameter of the convex portion 31 provided on the sealing plate 30 is configured to be smaller than the diameter of the top portion 43 provided on the metal plate 40. The height of the convex portion 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 its entirety.

The material of the sealing plate 30 may be, for example, a metal whose main component is aluminum. As described above, the sealing plate 30 is crimped and fixed to the opening of the exterior can 16 via the gasket 24.

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 portion 33 located on the outer periphery of the current collecting plate 32, and a recess 34 provided radially inside the peripheral portion 33 and recessed downward relative to the peripheral portion 33.

The peripheral portion 33 has a circular ring shape and abuts against the underside of the sealing plate 30. The peripheral portion 33 is joined to the sealing plate 30 by laser welding. The number and area of the welds between the peripheral portion 33 and the sealing plate 30 are set, for example, taking into consideration the joint strength and resistance. The peripheral portion 33 is crimped and fixed to the opening of the outer can 16 via the gasket 24. By crimping and fixing the peripheral portion 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.

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 is disposed approximately parallel to the peripheral portion 33.

A through hole 32A is provided in the center of the recess 34. The positive electrode lead 20 extending from the positive electrode 11 passes through the through hole 32A as described above. The size of the through hole 32A can be set appropriately according to 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.

Below, the metal plate 40 will be described in detail 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 illustrated by hatching.

As shown in Figures 1, 3, and 4, the metal plate 40 is disposed between the sealing plate 30 and the current collector plate 32, and is a member that sandwiches the positive electrode lead 20 with the current collector plate 32. Examples of materials for the metal plate 40 include metals whose main component is aluminum.

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

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 when viewed from above, and a number 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 disposed substantially parallel to the flange portion 42. Note that the shape of the top portion 43 is not limited to a substantially circular shape when viewed from above, and may be substantially rectangular when viewed from above.

Here, the top 43 is joined to the sealing plate 30. More specifically, the top 43 is joined to the lower surface of the sealing plate 30, in the area 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. In general, the larger the area of the welds, the higher the joint strength and the lower the resistance. From the viewpoint of increasing the joint strength between the metal plate 40 and the sealing plate 30, it is preferable that the welds are formed in a circular shape when viewed from above. The method of joining the top 43 and the sealing plate 30 is not limited to laser welding, and they may be joined by an adhesive or the like.

By joining the top 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, the 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 top side of the battery (the sealing plate 30 side), improving the safety of the battery.

In addition, by joining the top 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.

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

In this embodiment, the side portion 44 extends in a direction inclined with respect to the axial direction. The inclination angle of the extension direction of the side 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. The side portion 44 may extend along the axial direction. That is, the side portion 44 may be provided approximately perpendicular to the flange portion 42 and the top portion 43.

As shown in FIG. 3, the four side portions 44 are arranged at equal angular intervals from one another in the circumferential direction. By arranging the side portions 44 at equal angular intervals from one another in the circumferential direction, when a load is applied to the metal plate 40 from outside the battery, the load applied to the side portions 44 is distributed, making the side 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.

Furthermore, it is preferable that the side portion 44 is connected to an area of 10% or more of the outer periphery of the top portion 43, and it is more preferable that the side portion 44 is connected to an area of 15% or more of the outer periphery of the top portion 43. In this case, the strength of the side portion 44 is increased, making it easier to increase the strength of the central portion of the sealing plate 30, and the effect of the present disclosure is more pronounced.

In addition, through holes 40A are formed between adjacent side 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 via the through holes 40A. This makes it possible to reduce the internal pressure of the battery.

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

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

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 performing laser welding with the positive electrode lead 20 sandwiched between the recess 34 of the current collector plate 32.

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 for example, it is large enough to cover almost 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% or more and 70% or less of the radius of the metal plate 40.

[Second embodiment]
Next, the configuration of a cylindrical battery 10X according to a second embodiment will be described with reference to Fig. 5 and Fig. 6. Fig. 5 is a schematic cross-sectional view of a cylindrical battery 10X, and Fig. 6 is a perspective view of an electrode body 14 constituting the cylindrical battery 10X. Below, the same reference numerals are used for configurations common to the first embodiment, and duplicated descriptions are omitted, and differences from the first embodiment will be mainly described.

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 body 14, a nonaqueous electrolyte (not shown), an outer can 16 that contains the electrode body 14 and the nonaqueous electrolyte, a sealing body 17 that closes the opening of the outer can 16, a current collector 32 arranged between the sealing body 17 and the electrode body 14, and a metal plate 40 that is joined to the upper surface of the current collector 32. On the other hand, as will be described in detail later, the electrode body 14 of the second embodiment differs from the first embodiment in that it does not have a positive electrode lead 20 (see FIG. 1) and 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 arranged above and below the electrode body 14.

As shown in FIG. 6, the electrode body 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 wound in a spiral shape with the separator 13 interposed therebetween. The positive electrode 11, the negative electrode 12, and the separator 13 that constitute the electrode body 14 are all long strip-shaped bodies, and are alternately stacked in the radial direction of the electrode body 14 by being wound in a spiral shape. In addition, the positive electrode 11 protrudes upward beyond the negative electrode 12 and the separator 13, and the negative electrode 12 protrudes downward beyond the positive electrode 11 and the separator 13.

The positive electrode 11 has a positive electrode core exposed portion 52 at its upper axial end where the positive electrode core 50 is exposed without the positive electrode mixture layer 51. The positive electrode core exposed portion 52 is provided over a range from the winding start end to the winding end end in the longitudinal direction of the long positive electrode 11. The negative electrode 12 has a negative electrode core exposed portion 62 at its lower axial end where the negative electrode core 60 is exposed without the negative electrode mixture layer 61. The negative electrode core exposed portion 62 is provided over a range from the winding start end to the winding end end in the longitudinal direction of the long negative electrode 12. For this reason, 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 core exposed portion 52 is, for example, 2 mm or more and 20 mm or less, and the width of the negative electrode core exposed portion 62 is, for example, 2 mm or more and 20 mm or less.

As shown in FIG. 5, the positive electrode core exposed portion 52 extends from the upper end surface of the electrode body 14 approximately 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, so that the internal resistance of the positive electrode 11 can be reduced compared to when a positive electrode lead 20 (see FIG. 1) is used.

Also, as shown in FIG. 5, the negative electrode core exposed portion 62 extends from the lower end surface of the electrode body 14 approximately 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 portion 16A of the outer can 16. Note that 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 portion 16A of the outer can 16. In other words, the electrode body 14 may not have a positive electrode lead 20 and may only have a negative electrode lead 21.

The metal plate 40 of the second embodiment has a convex portion 41 in the center, as in the first embodiment. The convex portion 41 has a top portion 43 and a side portion 44, and the top portion 43 is joined to the sealing plate 30. Even when the positive electrode core exposed portion 52 is joined to the underside of the metal plate 40, the top portion 43 of the metal plate 40 is joined to the sealing plate 30, thereby increasing the strength of the central portion of the sealing plate 30.

As described above, by disposing the metal plate 40 having the protrusion 41 between the sealing body 17 and the current collecting plate 32 and joining the top 43 of the protrusion 41 to the sealing body 17, 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, the internal pressure increases during an abnormality in the battery and a load is applied to the sealing plate 30 pushing it toward the outside of the battery. In addition, when a load is applied from the outside of the battery toward the inside of the battery, the sealing plate 30, the current collecting plate 32, and the metal plate 40 are prevented from bending and deforming toward the inside of the battery. As a result, the battery performance and safety can be ensured.

The above embodiment can be modified as appropriate without impairing the purpose of the present disclosure. For example, as shown in FIG. 7, a thin wall portion 45 formed so that the lower surface is recessed may be provided on the side surface portion 44 of the metal plate 40. The thin wall portion 45 functions as an easily deformable portion that deforms preferentially when the cylindrical battery 10 is pressed from the radial outside toward the radial inside. By providing the thin wall portion 45 on the lower surface of the side surface portion 44, when the cylindrical battery 10 is pressed from the radial outside toward the radial inside, the side surface portion 44 deforms so as to bend upward from the thin wall portion 45 as a starting point. In other words, by providing the thin wall portion 45 on the lower surface of the side surface portion 44, when the cylindrical battery 10 is pressed from the radial outside toward the radial inside, the metal plate 40 is prevented from deforming downward. This makes it possible to prevent the metal plate 40 from contacting the negative electrode 12, thereby ensuring battery performance.

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

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 described above. In the example shown in FIG. 7, the thin-walled portion 45 is formed by forming a V-shaped groove 46 on the underside of the side portion 44. The minimum thickness of the thin-walled portion 45 is, for example, 30% or more and 70% or less of the thickness of the portion of the side portion 44 other than the thin-walled portion 45.

Also, as shown in FIG. 8, the side portion 44 of the metal plate 40 may have a bent shape. By having the side portion 44 have a bent shape, when the cylindrical battery 10 is pressed from the radial outside toward the radial inside, the side portion 44 is deformed so as to be folded starting from the bent point. In other words, by having the side portion 44 have a bent shape, when the cylindrical battery 10 is pressed from the radial outside toward the radial inside, the metal plate 40 is prevented from deforming downward. This makes it possible to prevent the metal plate 40 from coming into contact with the negative electrode 12, thereby ensuring battery performance.

In the above embodiment, the first electrode is the positive electrode 11 and the second electrode is the negative electrode 12, 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 32, and the positive electrode lead 20 extending from the positive electrode 11 may be joined to the exterior can 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.

In the above embodiment, the top 43 of the convex portion 41 of the metal plate 40 is flat, but the top 43 may have an uneven shape. As shown in FIG. 9, the convex portion 41 of the metal plate 40 may have a plurality of steps. In addition, the top 43 of the convex portion 41 may be joined to the lower surface of the sealing plate 30, and the side portion 44 of the convex portion 41 may abut against the inner surface of the convex portion 31 of the sealing plate 30. With the above configuration, when the internal pressure of the battery increases, the space through which the gas flows increases, so that the internal pressure of the battery can be further reduced.

The present disclosure is further illustrated 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 that houses the electrode assembly; a sealing body that closes an opening of the outer can; a current collector plate that is arranged 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 a side portion, and has a convex portion provided in a central portion 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 described in configuration 1, wherein the electrode body 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 described in Configuration 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, and 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 a surface of the current collector facing the electrode body.
Configuration 4: The cylindrical battery according to any one of configurations 1 to 3, wherein the protrusion has a through hole.
Configuration 5: The cylindrical battery according to any one of configurations 1 to 4, wherein the protrusion has a plurality of the side surfaces, the side surfaces being arranged 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 surface portion extends along a direction inclined with respect to an axial direction of the outer casing, and an inclination angle of the extension direction of the side surface portion with respect to the axial direction of the outer casing 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 portion provided on an outer periphery of the current collector plate is joined to the sealing body.
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 abuts against the sealing body.

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 part, 32 current collector plate, 32A through hole, 33 periphery, 34 concave part, 40 metal plate, 41 convex part, 42 flange part, 43 top part, 44 side part, 45 thin part, 46 groove, 50 positive electrode core, 51 positive electrode mixture layer, 52 positive electrode core exposed part, 60 negative electrode core, 61 negative electrode mixture layer, 62 negative electrode core exposed part

Claims (10)

an electrode assembly in which a first electrode and a second electrode are wound with a separator interposed therebetween;
a cylindrical exterior can with a bottom that houses the electrode assembly;
a sealing body that closes an opening of the outer can;
a current collector plate disposed between the sealing body and the electrode body;
a metal plate joined to a surface of the current collector plate facing the sealing body;
A cylindrical battery comprising:
The metal plate is
a protrusion having a top portion and a side portion and provided at a center portion of the metal plate;
A flange portion provided around the protrusion;
having
A cylindrical battery, wherein the top is joined to the sealing body. The electrode body has an electrode lead connected to the first electrode,
The cylindrical battery according to claim 1 , wherein the electrode lead is sandwiched between the current collector plate and the metal plate. 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 at which the first electrode core is exposed is provided at an end portion of the electrode body on the sealing body side,
The cylindrical battery according to claim 1 , wherein the first electrode core exposed portion is joined to a surface of the current collector plate facing the electrode body. The cylindrical battery of claim 1, wherein the protrusion has a through hole. The protrusion has a plurality of side surfaces,
The cylindrical battery according to claim 1 , wherein the side surface portions are provided at equal angular intervals from each other in the circumferential direction. the side surface portion extends along a direction inclined with respect to an axial direction of the outer casing,
2. The cylindrical battery according to claim 1, wherein an inclination angle of the extension direction of the side surface portion with respect to an axial direction of the outer can is 30 degrees or more and 60 degrees or less. The cylindrical battery according to claim 1, wherein the peripheral portion provided on the outer periphery of the current collector plate is joined to the sealing body. The cylindrical battery according to claim 1, wherein the current collector plate is fixed to the opening of the outer can by crimping. The cylindrical battery of claim 1, wherein the protrusion has multiple steps. The cylindrical battery according to claim 1, wherein at least a portion of the side surface abuts against the sealing body.

Images