Battery

Abstract

A battery (10) comprises: an electrode body (14); an external can (20) that accommodates the electrode body (14); and a sealing body (19) that seals an opening positioned at an axial end of the external can (20), with a gasket (24) therebetween. The sealing body (19) has a rupture plate (22) and a plate member (21). The plate member (21) has an internal terminal part (41) which is electrically connected to a positive electrode (11) of the electrode body (14) and an insulation part (42) which is positioned at an outer edge side of the internal terminal part (41) and which is opposite from the rupture plate (22) in the axial direction. The rupture plate (22) and the internal terminal part (41) are joined by a joining part (43). The electrical connection between the rupture plate (22) and the internal terminal part (41) at the joining part (43) is cut off along with an increase in internal pressure.

Description

battery

[0001] The present disclosure relates to a battery with a current interrupt mechanism.

[0002] A conventional battery is a cylindrical battery described in Patent Document 1. This cylindrical battery includes an electrode assembly in which a positive electrode and a negative electrode are wound with a separator interposed therebetween, an outer can housing the electrode assembly, and a sealing body that seals an opening located on one axial side of the outer can via a gasket. The sealing body is electrically connected to the positive electrode, and the negative electrode is electrically connected to the outer can. The sealing body has a current interruption mechanism that interrupts the electrical connection between the positive electrode and the sealing body when the battery's internal pressure increases due to abnormal heat generation in the battery. The current interruption mechanism is provided to suppress further heat generation when the battery abnormally heats up, thereby achieving high safety.

[0003] JP 2016-225014 A

[0004] The cylindrical battery is provided with a sealing body that seals an opening located at the axial end of the outer can via an insulating member, the sealing body has a joint that joins a first plate member and a second plate member, the second plate member is electrically connected to one electrode of the electrode body, and the electrical connection at the joint is cut off when internal pressure increases due to abnormal heat generation.

[0005] In this case, if a ring-shaped insulating member is placed between the first plate member and the second plate member so as to surround the entire joint, the insulating member can effectively prevent the first plate member and the second plate member from becoming electrically conductive again after the electrical connection at the joint is cut off, thereby increasing safety.

[0006] However, even without such an insulating member, if re-conduction between the first plate member and the second plate member can be effectively prevented, high safety can be easily achieved regardless of the presence of an insulating member. Furthermore, this problem can occur not only in cylindrical batteries but also in prismatic batteries with current interruption mechanisms. Therefore, an object of the present disclosure is to provide a battery in which a sealing body has a joint that joins a conductive plate and a conductive portion, and which can prevent re-conduction between the conductive plate and the conductive portion after the electrical connection at the joint is interrupted due to an increase in internal pressure.

[0007] To solve the above problems, the present disclosure provides a battery comprising an electrode assembly in which a first electrode and a second electrode are wound with a separator interposed therebetween, an outer can housing the electrode assembly, and a sealing body sealing an opening located at an axial end of the outer can via an insulating member, the sealing body having a conductive plate and a plate member, the plate member having a conductive portion electrically connected to the first electrode and an insulating portion located on the outer edge of the conductive portion and facing the conductive plate in the vertical direction, the conductive plate and the conductive portion being joined at a joint, and the electrical connection between the conductive plate and the conductive portion at the joint is interrupted as internal pressure increases. Note that in a cylindrical battery, the vertical direction coincides with the axial direction, and the direction perpendicular to the vertical direction coincides with the radial direction.

[0008] According to the battery of the present disclosure, it is possible to prevent the conductive plate and the conductive portion from becoming electrically conductive again after the electrical connection at the joint joining the conductive plate and the plate member is interrupted due to an increase in internal pressure.

[0009] 1 is an axial cross-sectional view of a cylindrical battery according to an embodiment of the present disclosure; FIG. 2 is an axial cross-sectional view of a plate member of a first modified example; FIG. 3 is an axial cross-sectional view of a plate member of a second modified example; FIG. 4 is an axial cross-sectional view of a plate member of a third modified example; FIG. 5 is an axial cross-sectional view of a plate member of a fourth modified example; (a) is an axial cross-sectional view of a plate member of a fifth modified example, and (b) is a top view of the plate member of the fifth modified example when viewed from above in the axial direction.

[0010] Hereinafter, an embodiment of a battery according to the present disclosure will be described in detail with reference to the drawings. The battery according to the present disclosure may be a primary battery or a secondary battery. It may also be a battery using an aqueous electrolyte or a battery using a non-aqueous electrolyte. Hereinafter, a cylindrical lithium-ion secondary battery will be exemplified as a battery 10 according to one embodiment, but the battery according to the present disclosure is not limited thereto.

[0011] It is anticipated from the beginning that new embodiments will be constructed by appropriately combining the features of the embodiments and variations described below. In the following embodiments, the same components are designated by the same reference numerals in the drawings, and redundant explanations will be omitted. Furthermore, multiple drawings include schematic diagrams, and the dimensional ratios of the length, width, height, etc. of each component between different drawings do not necessarily match. In this specification, the sealing body 19 side in the axial direction (height direction) of the cylindrical battery 10 is referred to as "upper," and the bottom 20A side of the exterior can 20 in the axial direction is referred to as "lower." Among the components described below, components not recited in the independent claims representing the highest concepts are optional components and not essential components.

[0012] FIG. 1 is an axial cross-sectional view of a cylindrical battery 10 according to one embodiment of the present disclosure. As shown in FIG. 1 , the cylindrical battery (hereinafter simply referred to as battery) 10 includes an electrode assembly 14, a nonaqueous electrolyte, an outer can 20 that houses the electrode assembly 14 and the nonaqueous electrolyte, and a sealing body 19 that closes an opening located at the upper end of the outer can 20 via an annular gasket 24. The gasket 24 is an example of an insulating member. In the example shown in FIG. 1 , the outer can 20 has a cylindrical shape with a bottom, but the outer can may have openings at both the upper and lower ends, and each opening may be closed with one or more members.

[0013] The electrode assembly 14 includes a long positive electrode 11 constituting a first electrode, a long negative electrode 12 constituting a second electrode, and two long separators 13 interposed between the positive electrode 11 and the negative electrode 12, and has a wound structure in which the positive electrode 11 and the negative electrode 12 are wound with the separators 13 interposed therebetween. The negative electrode 12 is formed to be slightly larger than the positive electrode 11 in order to prevent lithium deposition. The negative electrode 12 is formed to be longer than the positive electrode 11 in the winding direction and axial direction. The two separators 13 are formed to be slightly larger than the positive electrode 11 and are arranged to sandwich the positive electrode 11. The separators 13 protrude above and below the positive electrode 11 and the negative electrode 12.

[0014] The non-aqueous electrolyte has ion conductivity (e.g., 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. 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. The electrolyte salt may include, for example, LiPF ６ Lithium salts such as

[0015] Examples of the solid electrolyte include solid or gel polymer electrolytes and inorganic solid electrolytes. 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. Examples of the matrix polymer include a polymer material that absorbs the non-aqueous solvent and gels. Examples of the polymer material include fluororesin, acrylic resin, and polyether resin. Examples of the inorganic solid electrolyte include materials known in all-solid-state lithium ion secondary batteries (e.g., oxide-based solid electrolytes, sulfide-based solid electrolytes, halide-based solid electrolytes, etc.).

[0016] The positive electrode 11 has a positive electrode core and positive electrode mixture layers formed on both sides of the positive electrode core. The positive electrode core can be made of a metal foil, 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 layer. The positive electrode mixture layer contains a positive electrode active material, a conductive agent, and a binder. The positive electrode is produced, for example, by applying a positive electrode mixture slurry containing a positive electrode active material, a conductive agent, a binder, etc., onto the positive electrode core, drying the coating, and then compressing it to form positive electrode mixture layers on both sides of the positive electrode core.

[0017] The positive electrode active material is mainly composed of a lithium-containing metal composite oxide. Examples of metal elements contained in the lithium-containing metal composite oxide include Ni, Co, Mn, Al, B, Mg, Ti, V, Cr, Fe, Cu, Zn, Ga, Sr, Zr, Nb, In, Sn, Ta, and W. An example of a preferred lithium-containing metal composite oxide is a composite oxide containing at least one of Ni, Co, Mn, and Al.

[0018] Examples of conductive agents contained in the positive electrode mixture layer include carbon black such as acetylene black and ketjen black, and carbon materials such as graphite. Examples of binders contained in the positive electrode mixture layer include fluororesins such as polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVdF), polyacrylonitrile (PAN), polyimide resins, acrylic resins, and polyolefin resins. These resins may be used in combination with cellulose derivatives such as carboxymethyl cellulose (CMC) or its salts, polyethylene oxide (PEO), and the like.

[0019] The negative electrode 12 has a negative electrode core and negative electrode mixture layers formed on both sides of the negative electrode core. The negative electrode core can be made of a metal foil, 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 layer. The negative electrode mixture layer contains a negative electrode active material and a binder. The negative electrode 12 is produced, for example, by applying a negative electrode mixture slurry containing the negative electrode active material and the binder onto 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.

[0020] The negative electrode active material generally uses a carbon material that reversibly absorbs and releases lithium ions. Preferred carbon materials are graphites such as natural graphite, such as flake graphite, lump graphite, and amorphous graphite, and artificial graphite, such as lump artificial graphite and graphitized mesophase carbon microbeads. The negative electrode mixture layer may contain a silicon (Si) material as the negative electrode active material. In addition, the negative electrode active material may be a metal other than Si that alloys with lithium, an alloy containing such a metal, or a compound containing such a metal.

[0021] As in the case of the positive electrode 11, fluororesin, PAN, polyimide resin, acrylic resin, polyolefin resin, or the like may be used as the binder contained in the negative electrode mixture layer, but styrene-butadiene rubber (SBR) or a modified product thereof is preferably used. In addition to SBR or the like, the negative electrode mixture layer may also contain, for example, CMC or a salt thereof, polyacrylic acid (PAA) or a salt thereof, polyvinyl alcohol, or the like.

[0022] A porous sheet having ion permeability and insulating properties is used for the separator 13. Specific examples of the porous sheet include a microporous thin film, a woven fabric, and a nonwoven fabric. Preferred materials for the separator 13 include polyolefin resins such as polyethylene and polypropylene, and cellulose. The separator 13 may have either a single-layer structure or a laminated structure. A heat-resistant layer or the like may be formed on the surface of the separator 13.

[0023] An upper insulating plate 15 is disposed above the electrode body 14, and a lower insulating plate 16 is disposed below the electrode body 14. In the example shown in FIG. 1 , a positive electrode lead 17 attached to the positive electrode 11 passes through a through hole in the upper insulating plate 15, extends toward the sealing body 19, and is connected to the underside of the sealing body 19 by welding or the like. On the other hand, a negative electrode lead 18 attached to the negative electrode 12 passes outside the lower insulating plate 16, extends toward the bottom 20A of the outer can 20, and is connected to the inner surface of the bottom 20A by welding or the like. The sealing body 19 to which the positive electrode lead 17 is connected serves as a positive electrode terminal, and the outer can 20 to which the negative electrode lead 18 is connected serves as a negative electrode terminal.

[0024] A gasket 24 is provided between the outer can 20 and the sealing body 19 to ensure sealing of the battery interior and insulation between the outer can 20 and the sealing body 19. The outer can 20 has a cylindrical portion 20B and a bottom portion 20A. The cylindrical portion 20B includes an annular grooved portion 28 and an annular shoulder portion 29. The grooved portion 28 is formed by spinning a portion of the cylindrical portion 20B to recess it radially inward. The shoulder portion 29, on the other hand, is formed when the upper end of the cylindrical portion 20B is bent radially inward and crimped to a flange portion (peripheral portion) 31 of the sealing body 19, and extends radially inward. The crimping causes the sealing body 19 to be sandwiched between the shoulder portion 29 and the grooved portion 28 via the gasket 24, and the sealing body 19 is fixed to the outer can 20.

[0025] The sealing body 19 is equipped with a current interruption mechanism. The sealing body 19 has a structure in which, from the electrode body 14 side, an integrated plate member 21, an annular insulating plate 23, and a rupture plate 22 are stacked. The plate member 21 has an internal terminal portion 41 electrically connected to the positive electrode 11 and an annular insulating portion 42 located on the outer edge side of the internal terminal portion 41. The insulating portion 42 axially faces the rupture plate 22 via the insulating plate 23. The rupture plate 22 is an example of a conductive plate, and the internal terminal portion 41 is an example of a conductive portion. The rupture plate 22 constitutes a valve body and is disposed opposite the plate member 21 across the insulating plate 23. The insulating plate 23 has an opening 23A formed in its radial center, and an air vent 23B provided in a portion overlapping with the air vent 21C of the internal terminal portion 41.

[0026] The rupture plate 22 has a valve portion 22A at its radial center that ruptures in response to an increase in battery internal pressure. The valve portion 22A and the internal terminal portion 41 are joined at a joint portion 43. Specifically, the valve portion 22A is joined by welding or the like to a central portion 21B of the internal terminal portion 41 through an opening 23A of the insulating plate 23. The valve portion 22A includes a protrusion 33 that is provided at the radial center and protrudes downward, and a thin-walled portion 34 that is provided radially outward of the protrusion 33. The thickness of the thin-walled portion 34 becomes thinner as it extends radially outward.

[0027] The thickness of the thin-walled portion 34 becomes thinner radially outward, so that an annular space 39 is provided below the thin-walled portion 34. The insulating portion 42 of the plate member 21 has an opposing portion 42a that faces the space 39 in the axial direction. The insulating plate 23 is located radially outward of the protruding portion 33. The insulating plate 23 is located between the rupture plate 22 and the plate member 21 and is arranged so as to surround the joint portion 43 over the entire circumference.

[0028] The rupture plate 22 holds the insulating plate 23, and the insulating plate 23 holds the plate member 21. Specifically, the rupture plate 22 includes an annular thick-walled portion 35 connected to the radially outer end of the thin-walled portion 34, and the thick-walled portion 35 has an annular protruding portion 37 protruding downward. The outer peripheral surface of the insulating plate 23 is fitted and fixed to the inner peripheral surface of the annular protruding portion 37. The insulating plate 23 also has an annular protruding portion 38 protruding downward on the outer peripheral side, and the inner peripheral surface of the annular protruding portion 38 is fitted and fixed to the outer peripheral surface of the plate member 21. The insulating plate 23 includes a clamping portion that is clamped radially between the annular protruding portion 37 and the plate member 21.

[0029] The internal terminal portion 41 is made of metal and has a thick annular portion 21A. The central portion 21B is connected to the radially inner end of the annular portion 21A. The central portion 21B has a disk shape and is thinner than the annular portion 21A. The vent hole 21C is provided in the annular portion 21A. The positive electrode lead 17 is joined to the underside of the annular portion 21A. The internal terminal portion 41 to which the positive electrode lead 17 is connected is electrically connected to the rupture plate 22, thereby forming a current path connecting the electrode body 14 to the rupture plate 22.

[0030] The plate member 21 can be fabricated, for example, as follows. First, an aluminum plate member having substantially the same shape as the plate member 21 is prepared. Then, the annular outer edge of the aluminum plate member is brought into contact with an oxidizing agent, such as hydrogen peroxide, nitric acid, or chromic acid, to grow alumina (aluminum oxide) on the outer edge and modify the outer edge to alumina (aluminum oxide). The annular outer edge of the aluminum plate member may be converted to aluminum hydroxide, and then the aluminum hydroxide may be calcined at a high temperature to modify the outer edge to alumina.

[0031] Aluminum is a metal and has electrical conductivity, while alumina is a nonmetal (ceramic) and has insulating properties but not electrical conductivity. Thus, a plate member in which the conductive portion located in the center is made of a conductive material containing aluminum, while the insulating portion located on the outer edge is made of an insulating material containing alumina, can be easily produced by simply modifying the aluminum at the annular outer edge of the plate member to alumina. The conductive portion may be made of a conductive material other than aluminum, and the insulating portion may be made of an insulating material other than alumina.

[0032] In the above configuration, if the battery 10 generates abnormal heat and the internal battery pressure rises, the valve portion 22A flips over so as to become convex axially upward, using the annular end 22B, which is the radially outer, less rigid part of the thin-walled portion 34, as a fulcrum. Simultaneously with this flip, the central portion 21B is separated from the annular portion 21A or disengages from the valve portion 22A. Because the valve portion 22A is insulated from the annular portion 21A by the insulating plate 23, this flip interrupts the current path. If the internal battery pressure rises further, the annular end 22B of the thin-walled portion 34 breaks, forming a gas outlet.

[0033] Furthermore, even if the insulating plate 23 melts due to abnormal heat generation in the battery 10, the outer edge of the plate member 21 forms the insulating portion 42, so the thick portion 35 of the rupture plate 22 is likely to come into contact with the insulating portion 42. Therefore, re-conduction between the rupture plate 22 and the internal terminal portion 41 can be effectively prevented, achieving high safety. Furthermore, in this embodiment, the insulating portion 42 of the plate member 21 has an opposing portion 42a that axially faces the space 39, so contact between the internal terminal portion 41 and the thick portion 35 can be effectively prevented. Therefore, safety can be further improved.

[0034] The sealing body does not have to have an insulating plate. However, as in the present embodiment, when sealing body 19 includes an annular insulating plate 23 that is positioned between rupture plate (conductive plate) 22 and plate member 21 and that is arranged so as to surround joint portion 43 over the entire periphery, re-conduction between rupture plate 22 and internal terminal portion (conductive portion) 41 can be more effectively suppressed, thereby ensuring complete safety.

[0035] Since this can effectively prevent re-conduction between the rupture plate 22 and the internal terminal portion 41 after the conduction between the rupture plate (conductive plate) 22 and the internal terminal portion (conductive portion) 41 is interrupted at the joint 43, it is preferable that the radial length of the insulating portion 42 be 3% or more of the radial length of the plate member 21. Furthermore, since this makes it easy to reduce the weight of the plate member 21 and to reduce the electrical resistance, it is preferable that the radial length of the insulating portion 42 be 10% or less of the radial length of the plate member 21.

[0036] The present disclosure is not limited to the above-described embodiment and its modifications, and various improvements and modifications are possible within the scope of the claims of the present application and their equivalents.

[0037] For example, in the above embodiment, as shown in Fig. 1, the upper surface of the thick-walled annular portion 21A of the internal terminal portion 41 and the upper surface of the insulating portion 42 are flush with each other and are located at approximately the same axial position. However, as shown in Fig. 2, i.e., the axial cross-sectional view of the plate member 121 of the first modified example, the plate member 121 may have an internal terminal portion 141 that constitutes a conductive portion and is located in the center, and an insulating portion 142 that is located on the outer edge side of the internal terminal portion 141. The insulating portion 142 may have a first protrusion 142a that protrudes further toward the conductive plate (e.g., rupture plate) in the axial direction than the outer edge side end portion 141a of the internal terminal portion 141.

[0038] In this case, the first protrusion 142 a can be brought into contact with the conductive plate (e.g., a rupture plate) preferentially after the conduction at the joint between the conductive plate and the internal terminal portion 141 is interrupted, and the portion of the plate member 121 that comes into contact with the conductive plate can be limited to the first protrusion 142 a. Therefore, re-establishment of conduction between the conductive plate and the internal terminal portion 141 can be prevented, thereby achieving extremely high safety.

[0039] Fig. 3 is an axial cross-sectional view of a plate member 221 of a second modified example, Fig. 4 is an axial cross-sectional view of a plate member 321 of a third modified example, and Fig. 5 is an axial cross-sectional view of a plate member 421 of a fourth modified example. Referring to Figs. 3 to 5, the plate members 221, 321, and 421 have an integral structure. The plate members 221, 321, and 421 also have internal terminal portions 241, 341, and 441 that form conductive portions and are located in the center, and insulating portions 242, 342, and 442 that are located on the outer edge sides of the internal terminal portions 241, 341, and 441.

[0040] 3 to 5 , the insulating portion 242, 342, 442 has a second protrusion 242b, 342b, 442b that protrudes radially inward on the axially conductive plate side (axially upward). More specifically, the insulating portion 242, 342, 442 has a first protrusion 242a, 342a, 442a that protrudes axially toward the conductive plate beyond the outer edge of the internal terminal 241, 341, 441, and the second protrusion 242b, 342b, 442b protrudes radially inward from the first protrusion 242a, 342a, 442a. The second protrusion 242b, 342b, 442b overlaps the internal terminal 241, 341, 441 in the axial direction (thickness direction of the plate member 221, 321, 421).

[0041] As shown in Fig. 3, the second protrusion 242b may be an annular protrusion, and as shown in Fig. 4, the second protrusion 342b may be a protrusion provided only on a portion of the circumference. Also, as shown in Figs. 3 and 4, the second protrusion 242b may be molded integrally with the insulating portion 242, 342 other than the second protrusions 242b, 342b. As shown in Fig. 5, the second protrusion 442b may be fixed to the first protrusion 442a by a fixing means such as fusion bonding or an insulating adhesive.

[0042] The internal terminal portion 241, 341, 441 has a cylindrical outer peripheral surface 241 a, 341 a, 441 a. On the other hand, the lower surface of the second protrusion 242 b, 342 b, 442 b extends in a direction substantially perpendicular to the thickness direction of the plate member 221, 321, 421. The insulating portion 242, 342, 442 has a cylindrical inner peripheral surface 242 c, 342 c, 442 c extending axially downward from a radially inner end of the lower surface of the second protrusion 242 b, 342 b, 442 b.

[0043] According to the plate members 221, 331, 441 of the second to fourth modified examples, it is possible to increase the area of ​​the upper end face of the plate member 221, 321, 421 that is configured by the insulating portion 242, 342, 442. This makes it possible to more reliably prevent re-conduction between the conductive plate and the internal terminal portion 241, 341, 441, thereby achieving high safety.

[0044] Furthermore, it is possible to easily manufacture the plate member 221, 321, 421 as an integrated unit with high precision by simply pressing the cylindrical inner peripheral surface 242c, 342c, 442c into the cylindrical outer peripheral surface 241a, 341a, 441a until the second protrusion 242b, 342b, 442b contacts the upper end surface of the internal terminal portion 241, 341, 441. In other words, the insulating portion 242, 342, 442 can be used as a stopper when the insulating portion 242, 342, 442 is pressed into the internal terminal portion 241, 341, 441, and it is possible to easily manufacture the plate member 221, 321, 421 as an integrated unit with high precision.

[0045] 6( a) is an axial cross-sectional view of a plate member 521 of a fifth modified example, and FIG. 6( b) is a top view of the plate member 521 of the fifth modified example as viewed from above in the axial direction. In the above embodiment, the insulating portion 42 has an annular structure. However, as shown in FIG. 6( b), the insulating portion 542 does not have to have an annular structure. For example, the insulating portion 542 may be composed of a plurality of insulating pieces 542 a arranged at intervals in the circumferential direction.

[0046] In this case, the insulating portion 542 can be fabricated by fixing a plurality of insulating piece portions 542a at intervals in the circumferential direction to the outer edge portion of the upper surface of the internal terminal portion 541 that constitutes the conductive portion using a fixing means such as an adhesive or melt-fixing of the joining surface. A configuration in which only one non-annular insulating portion is fixed to the outer edge portion of the upper surface of the internal terminal portion 541 may also be used.

[0047] The annular groove 590 is provided to facilitate smooth separation of the central portion 521B from the annular portion 521A, allowing the current interruption mechanism to operate appropriately in the event of abnormal battery heat generation. The through-hole 521c is provided to allow high-pressure air to press against the underside of the rupture plate in the event of abnormal battery heat generation. The above description deals with the case where the first electrode electrically connected to the sealing body 19 is the positive electrode 11, and the second electrode electrically connected to the outer can 16 is the negative electrode 12. However, the first electrode electrically connected to the sealing body may be the negative electrode, and the second electrode electrically connected to the outer can 16 may be the positive electrode.

[0048] Although the battery has been described as being cylindrical, it may also be prismatic. The vertical direction of a battery coincides with the axial direction in cylindrical batteries, while it is the same as the vertical direction in prismatic batteries. The perpendicular direction perpendicular to the vertical direction of a battery coincides with the radial direction in cylindrical batteries, while it is the same as the perpendicular direction perpendicular to the vertical direction in prismatic batteries. Furthermore, the ratio of the radial length of the insulating portion to the radial length of the plate member in cylindrical batteries can be approximated by the ratio of the length of the line segment with the shortest length that extends in the perpendicular direction perpendicular to the vertical direction and connects the outer edge of the insulating portion to the center of the plate member to the length of the line segment that passes through the insulating portion. Note that the line segment with the shortest length extends through the vertical position where the insulating portion exists, and the center of the plate member refers to the center of the plate member in a plane perpendicular to the vertical direction.

[0049] For this reason, in prismatic batteries, since this effectively prevents re-establishment of conduction between the conductive plate and the conductive part after the conduction at the joint between the conductive plate and the conductive part is interrupted, it is preferable that the length of the portion of the line segment that extends in the orthogonal direction perpendicular to the up-down direction and has the shortest length connecting the outer edge of the insulating part to the center of the plate member that passes through the insulating part be 3% or more of the length of the line segment.Furthermore, in prismatic batteries, since this facilitates the realization of a lightweight plate member and low electrical resistance, it is preferable that the length of the portion of the line segment that extends in the orthogonal direction perpendicular to the up-down direction and has the shortest length connecting the outer edge of the insulating part to the center of the plate member that passes through the insulating part be 10% or less of the length of the line segment.

[0050] The battery of the present disclosure may also have the following configurations. Configuration 1: A battery comprising: an electrode assembly in which a first electrode and a second electrode are wound with a separator interposed therebetween; an outer can housing the electrode assembly; and a sealing body sealing an opening located at an axial end of the outer can via an insulating member, wherein the sealing body has a conductive plate and a plate member, and the plate member has a conductive portion electrically connected to the first electrode and an insulating portion located on the outer edge of the conductive portion and facing the conductive plate in the vertical direction, the conductive plate and the conductive portion being joined at a joint portion, and the electrical connection between the conductive plate and the conductive portion at the joint portion is interrupted as internal pressure increases. Configuration 2: The battery according to Configuration 1, further comprising: an annular insulating plate located between the conductive plate and the plate member and arranged to surround the joint portion all around. Configuration 3: The battery according to Configuration 1 or 2, wherein the insulating portion has a first protrusion that protrudes axially toward the conductive plate beyond an outer edge of the conductive portion. Configuration 4: The battery according to any one of configurations 1 to 3, wherein, for a line segment that extends in a direction perpendicular to the up-down direction and has the shortest length connecting the outer edge of the insulating portion and the center of the plate member, the length of a portion of the line segment that passes through the insulating portion is 3% or more of the length of the line segment.Configuration 5: The battery according to any one of configurations 1 to 4, wherein, for a line segment that extends in a direction perpendicular to the up-down direction and has the shortest length connecting the outer edge of the insulating portion and the center of the plate member, the length of a portion of the line segment that passes through the insulating portion is 10% or less of the length of the line segment.Configuration 6: The battery according to any one of configurations 1 to 5, wherein the conductive portion is made of a conductive material containing aluminum, and the insulating portion is made of an insulating material containing aluminum oxide.Configuration 7: The battery according to any one of configurations 1 to 6, wherein the insulating portion has a second protruding portion that protrudes inward in the orthogonal direction perpendicular to the up-down direction on the side of the conductive plate in the up-down direction, and the second protruding portion overlaps the conductive portion in the up-down direction.

[0051] REFERENCE SIGNS LIST 10 Battery, 11 Positive electrode, 12 Negative electrode, 13 Separator, 14 Electrode body, 15 Upper insulating plate, 16 Lower insulating plate, 17 Positive electrode lead, 18 Negative electrode lead, 19 Sealing body, 20 Outer can, 20A Bottom, 20B Cylindrical portion, 21, 121, 221, 321, 421, 521 Plate member, 21A, 521A Annular portion, 21B, 521B Central portion, 21C, 521C Vent, 22 Rupture plate (conductive plate), 22A Valve portion, 22B Annular end portion, 23 Insulating plate, 23A Opening, 23B Vent, 24 Gasket, 28 Grooved portion, 29 Shoulder portion, 33 Protruding portion, 34 Thin-walled portion, 35 Thick-walled portion, 37 Annular protrusion of rupture plate, 38 Annular protrusion of insulator, 39 Space, 41, 141, 242, 341, 441, 541 Internal terminal portion, 42, 142, 242, 342, 442, 542 Insulating portion, 42a Opposing portion, 43 Joint portion, 141a Outer edge side end portion, 142a, 242a, 342a, 442a First protrusion portion, 241a Cylinder outer peripheral surface, 242b, 342b, 442b Second protrusion portion, 242c Cylinder inner peripheral surface, 542a Insulating piece portion, 590 Annular groove.

Claims

1. A battery comprising: an electrode assembly in which a first electrode and a second electrode are wound with a separator interposed therebetween; an outer can that houses the electrode assembly; and a sealing body that seals an opening located at an axial end of the outer can via an insulating member, wherein the sealing body has a conductive plate and a plate member, and the plate member has a conductive portion electrically connected to the first electrode and an insulating portion located on the outer edge of the conductive portion and facing the conductive plate in the vertical direction, the conductive plate and the conductive portion being joined at a joint, and the electrical connection between the conductive plate and the conductive portion at the joint is interrupted as internal pressure increases.

2. The battery according to claim 1, further comprising an annular insulating plate positioned between said conductive plate and said plate member and arranged so as to surround said joint over the entire periphery.

3. The battery according to claim 1 or 2, wherein the insulating portion has a first protruding portion that protrudes axially toward the conductive plate beyond the outer edge of the conductive portion.

4. A battery as described in claim 1 or 2, wherein, with respect to a line segment of minimum length extending in a direction perpendicular to the vertical direction and connecting the outer edge of the insulating portion to the center of the plate member, the length of the portion of the line segment that passes through the insulating portion is 3% or more of the length of the line segment.

5. A battery as described in claim 1 or 2, wherein, with respect to a line segment of minimum length extending in a direction perpendicular to the vertical direction and connecting the outer edge of the insulating portion to the center of the plate member, the length of the portion of the line segment that passes through the insulating portion is 10% or less of the length of the line segment.

6. The battery according to claim 1 or 2, wherein the conductive portion is made of a conductive material containing aluminum, and the insulating portion is made of an insulating material containing aluminum oxide.

7. The battery according to claim 1 or 2, wherein the insulating portion has a second protruding portion that protrudes inward in a direction perpendicular to the vertical direction on the conductive plate side in the vertical direction, and the second protruding portion overlaps the conductive portion in the vertical direction.

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