Non-aqueous electrolyte secondary battery

Abstract

This non-aqueous electrolyte secondary battery (10) comprises an electrode body, a non-aqueous electrolyte, a cylindrical outer can (20) with a bottom that accommodates the electrode body and the non-aqueous electrolyte, a sealing body (30) closing an opening (24) of the outer can (20), an annular gasket (34) disposed between the outer can (20) and the sealing body (30), and a protective member (40) disposed between the outer can (20) and the gasket (34), and is characterized in that: the outer can (20) has a crimping portion (26) that extends radially inward and fixes the sealing body by crimping; and the protective member (40) has an exposed portion (41) disposed radially inward of a radial inner end (26A) of the crimping portion (26).

Description

Nonaqueous electrolyte secondary battery

[0001] The present disclosure relates to a non-aqueous electrolyte secondary battery.

[0002] Conventionally, non-aqueous electrolyte secondary batteries have been known that include a cylindrical outer can with a bottom that houses an electrode assembly and a non-aqueous electrolyte, and a sealing member that closes the opening of the outer can. The interior of the non-aqueous electrolyte secondary battery is sealed by crimping the sealing member between an annular groove formed in the side surface of the outer can and the open edge of the outer can. Patent Document 1 discloses a non-aqueous electrolyte secondary battery that includes a sealant containing a soft polymer and an imidazole compound, with the aim of improving the sealing performance of the non-aqueous electrolyte secondary battery and suppressing leakage of the non-aqueous electrolyte.

[0003] JP 2011-014371 A

[0004] However, even if the sealing property of a non-aqueous electrolyte secondary battery is improved, it is difficult to completely prevent leakage of the non-aqueous electrolyte. If leakage of the non-aqueous electrolyte occurs, the non-aqueous electrolyte may come into contact with the outer can, causing rust on the outer can. Therefore, it is an important issue to prevent rust on the outer can when leakage of the non-aqueous electrolyte occurs.

[0005] A nonaqueous electrolyte secondary battery according to one aspect of the present disclosure is a nonaqueous electrolyte secondary battery comprising: an electrode assembly having a positive electrode and a negative electrode; a nonaqueous electrolyte; a cylindrical outer can with a bottom that accommodates the electrode assembly and the nonaqueous electrolyte; a sealing body that closes the opening of the outer can; an annular gasket that is disposed between the outer can and the sealing body; and a protective member that is disposed between the outer can and the gasket, wherein the outer can has a crimped portion that extends radially inward and crimps and fixes the sealing body, and the protective member has an exposed portion that is disposed radially inward of the radial inner end of the crimped portion.

[0006] According to the nonaqueous electrolyte secondary battery of one aspect of the present disclosure, even if leakage of the nonaqueous electrolyte solution occurs, the occurrence of rust on the outer can can be suppressed.

[0007] Fig. 1 is an axial cross-sectional view of a nonaqueous electrolyte secondary battery according to an embodiment; Fig. 2 is an enlarged view of the vicinity of an opening in Fig. 1; Fig. 3 is a schematic view of the flow of nonaqueous electrolyte in Fig. 2; Fig. 4 is an axial cross-sectional view of a nonaqueous electrolyte secondary battery according to another embodiment, showing an enlarged view of the vicinity of an opening.

[0008] Hereinafter, an example of an embodiment of a nonaqueous electrolyte secondary 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 embodiments obtained by selectively combining the components of the embodiments described below.

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

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

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

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

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

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

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

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

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

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

[0019] A positive electrode lead 18 is connected to the positive electrode 11, and a negative electrode lead 19 is connected to the winding end side of the negative electrode 12. The positive electrode lead 18 passes through a through hole in the insulating plate 16 and extends toward the sealing body 30, and the negative electrode lead 19 passes outside the insulating plate 17 and extends toward the bottom 21 of the outer can 20. The positive electrode lead 18 is connected to the underside of an internal terminal plate 31 of the sealing body 30 by welding or the like, and the sealing body 30 serves as a positive electrode terminal. The negative electrode lead 19 is connected to the inner surface of the bottom 21 of the metal outer can 20 by welding or the like, and the outer can 20 serves as a negative electrode terminal.

[0020] The nonaqueous solvent (organic solvent) of the nonaqueous electrolyte solution contained in the outer can 20 can be carbonates, lactones, ethers, ketones, esters, etc., and two or more of these solvents can be mixed and used. When two or more solvents are mixed and used, it is preferable to use a mixed solvent containing a cyclic carbonate and a chain carbonate. For example, ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), etc. can be used as the cyclic carbonate, and dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), etc. can be used as the chain carbonate. The electrolyte salt of the nonaqueous electrolyte solution can be LiPF ６ , LiBF ４ , LiCF ３ SO ３The amount of electrolyte salt dissolved in the non-aqueous solvent can be, for example, 0.5 mol / L or more and 2.0 mol / L or less.

[0021] The exterior can 20 is a cylindrical metal container with a bottom that is open on one axial side. The exterior can 20 has a bottom 21 and a side surface 22 that forms the side surface of the nonaqueous electrolyte secondary battery 10. The side surface 22 is the portion of the exterior can 20 excluding the bottom 21, and includes a grooved portion 23 and an opening 24, which will be described later.

[0022] The grooved portion 23 is a portion of the side surface portion 22 recessed radially inward, and is provided in an annular shape along the circumferential direction of the outer can 20. The upper surface of the grooved portion 23 supports the sealing body 30. The grooved portion 23 can be formed, for example, by spinning a portion of the side surface portion 22 radially inward to recess it in an annular shape radially inward.

[0023] The opening 24 is a region of the side surface portion 22 above the grooved portion 23 and forms an opening in the outer can 20. The opening 24 is bent radially inward when the sealing body 30 is crimped to the outer can 20. As a result, the opening 24 is formed with an opening side surface portion 25 that forms a portion of the side surface of the nonaqueous electrolyte secondary battery 10 and covers the outer peripheral surface of the gasket 34, and a crimped portion 26 that forms a portion of the upper surface of the nonaqueous electrolyte secondary battery 10 and extends radially inward. Furthermore, a radially inner end 26A (see FIG. 2 ) of the crimped portion 26 is located radially outward of a radially inner end 34A (see FIG. 2 ) of the gasket 34. In other words, a portion of the upper surface of the gasket 34 is not covered by the crimped portion 26. As will be described in detail later, a protective tape 40 serving as a protective member is disposed between the opening 24 of the outer can 20 and the gasket 34.

[0024] The sealing body 30 is a disc-shaped member equipped with a safety valve. The sealing body 30 has a structure in which an internal terminal plate 31, an insulating member 32, and an external terminal plate 33 are stacked in this order from the electrode body 14 side.

[0025] The internal terminal plate 31 is a metal plate including a thick portion 31A to which the positive electrode lead 18 is connected and a thin central portion 31B that is separated from the thick portion 31A when the internal pressure of the battery exceeds a predetermined threshold. A plurality of vent holes 31C are formed in the thick portion 31A.

[0026] The insulating member 32 insulates the portions other than the connection portion between the internal terminal plate 31 and the external terminal plate 33. The insulating member 32 has an opening 32A formed in the radial center thereof, and an air vent 32B formed in a portion overlapping with the air vent 31C of the internal terminal plate 31.

[0027] The external terminal plate 33 forms part of the upper surface of the nonaqueous electrolyte secondary battery 10 and is disposed opposite the internal terminal plate 31 with the insulating member 32 sandwiched therebetween. The external terminal plate 33 has a thin-walled portion 33A that breaks when the internal pressure of the nonaqueous electrolyte secondary battery 10 exceeds a predetermined threshold. The external terminal plate 33 is connected at its radial center to a central portion 31B of the internal terminal plate 31 by welding or the like. The radial outer side of the external terminal plate 33 is sandwiched, via a gasket 34, between the crimped portion 26 formed by bending the opening of the outer can 20 inward and the grooved portion 23.

[0028] When an abnormality occurs in the nonaqueous electrolyte secondary battery 10 and the internal pressure rises, the generated high-temperature gas pushes the internal terminal plate 31 upward, causing the internal terminal plate 31 to break, separating the central portion 31B from the thick portion 31A, and deforming the external terminal plate 33 so that it protrudes toward the outside of the battery, thereby interrupting the current path in the sealing body 30. Then, when the internal pressure of the nonaqueous electrolyte secondary battery 10 rises further after the current path is interrupted, the thin portion 33A of the external terminal plate 33 breaks, forming a gas outlet in the external terminal plate 33.

[0029] The structure of sealing body 30 is not limited to the structure shown in Fig. 1. Sealing body 30 may have, for example, a convex cap that covers external terminal board 33.

[0030] The gasket 34 is a flexible insulating member that electrically isolates the sealing body 30, which is the positive electrode terminal, from the outer can 20, which is the negative electrode terminal, while being compressed in the vertical direction to ensure the airtightness of the interior of the outer can 20. The material of the gasket 34 is not particularly limited as long as it is a compressible insulating material, and examples that can be used include polypropylene (PP), polyphenylene sulfide (PPS), polyethylene (PE), polybutylene terephthalate (PBT), perfluoroalkoxyalkane (PFA), polytetrafluoroethylene (PTFE), and polyamide (PA).

[0031] Next, the sealing state of the opening 24 of the nonaqueous electrolyte secondary battery 10 and the protective tape 40 as a protective member will be described with reference to Figures 2 and 3. Figure 2 is an enlarged view of the vicinity of the opening 24, and Figure 3 is a diagram schematically illustrating the movement path of the nonaqueous electrolyte in Figure 2.

[0032] 2 , a protective tape 40 serving as a protective member is disposed between the opening 24 of the exterior can 20 and the gasket 34. Specifically, the protective tape 40 is disposed between the opening 24 and the top surface 34B and side surface 34C of the gasket 34. The protective tape 40 is attached to the inner surface of the opening 24.

[0033] Here, the protective tape 40 has an exposed portion 41 that is disposed radially inward of the radial inner end 26A of the crimped portion 26. In other words, the exposed portion 41 is not covered by the crimped portion 26, and is disposed with its upper surface exposed.

[0034] As shown in FIG. 3 , nonaqueous electrolyte inside the exterior can 20 may penetrate the interface between the protective tape 40 and the gasket 34 due to an external impact or the like from the battery. The penetrated nonaqueous electrolyte may then move upward through the gap between the protective tape 40 and the gasket 34 toward the top of the battery and leak out of the battery. In this case, the protective tape 40 has an exposed portion 41, which prevents the nonaqueous electrolyte leaking out of the battery from migrating toward the crimped portion 26. As a result, rusting of the exterior can 20 due to contact of the crimped portion 26 with the nonaqueous electrolyte can be suppressed. In other words, if the protective tape 40 did not have the exposed portion 41, nonaqueous electrolyte leaking out of the battery from the interface between the protective tape 40 and the gasket 34 would come into contact with the crimped portion 26, causing rusting of the exterior can 20. Rust on the exterior can 20 not only causes poor appearance but also may degrade battery performance, which is undesirable.

[0035] 2 , the radially inner end 41A of the exposed portion 41 is preferably positioned radially inward of the radially inner end 34A of the gasket 34. In other words, the upper surface 34B of the gasket 34 is preferably covered with the protective tape 40. In this case, nonaqueous electrolyte that leaks from the interface between the protective tape 40 and the gasket 34 to the outside of the battery is more likely to flow toward the center of the battery. As a result, the leaked nonaqueous electrolyte is further prevented from coming into contact with the crimped portion 26.

[0036] The radial length of the exposed portion 41 is preferably 0.10 mm or more, more preferably 0.15 mm or more, and even more preferably 0.20 mm or more. Here, the radial length of the exposed portion 41 refers to the length along the radial direction of the outer can 20 from the radially inner end 26A of the crimped portion 26 to the radially inner end 41A of the exposed portion 41. By making the radial length of the exposed portion 41 0.10 mm or more, nonaqueous electrolyte leaking from the interface between the protective tape 40 and the gasket 34 to the outside of the battery can be further prevented from coming into contact with the crimped portion 26. The upper limit of the radial length of the exposed portion 41 is not particularly limited, but is, for example, 2.0 mm. Note that if the protective tape 40 is conductive, the protective tape 40 needs to be positioned so as not to come into contact with the sealing body 30.

[0037] The exposed portion 41 is preferably provided along the entire circumferential direction of the outer can 20. In this case, it is possible to prevent the leaked nonaqueous electrolyte from coming into contact with the crimped portion 26 along the entire circumferential direction of the outer can 20.

[0038] The protective tape 40 includes, for example, a substrate and an adhesive portion formed on one surface of the substrate. The substrate may be made of an insulating resin material or a conductive metal material. By providing the protective tape 40, the distance between the sealing body 30 and the outer can 20 can be increased by the thickness of the protective tape 40. Therefore, by forming the substrate from an insulating material, it is easy to ensure insulation between the sealing body 30 and the outer can 20. Furthermore, by forming the substrate from an insulating material, the protective tape 40 can insulate the sealing body 30 from the outer can 20 when the gasket 34 melts during abnormal heat generation in the battery due to an external short circuit or the like. The thickness of the substrate is, for example, 5 μm or more and 50 μm or less, and preferably 5 μm or more and 30 μm or less.

[0039] Examples of insulating resin materials that can be used to form the base material include PI (polyimide), PP (polypropylene), PPS (polyphenylene sulfide), PEEK (polyether ether ketone), PET (polyethylene terephthalate), PBT (polybutylene terephthalate), etc. Among these, it is preferable to use PI (polyimide) from the viewpoint of ensuring the heat resistance of the protective tape 40.

[0040] The adhesive portion is a portion for adhering the protective tape 40 to the inner surface of the outer can 20. The thickness of the adhesive portion is, for example, 1 μm or more and 30 μm or less, and preferably 2 μm or more and 25 μm or less. The adhesive portion contains, for example, at least one of a rubber-based polymer, an acrylic-based polymer, and a silicone-based polymer. The rubber-based polymer, the acrylic-based polymer, and the silicone-based polymer have adhesive properties, and therefore can adhere the protective tape 40 to the inner surface of the outer can 20.

[0041] Next, an example of a method for manufacturing a nonaqueous electrolyte secondary battery including a protective tape 40 will be described. First, the protective tape 40 is attached to the inner surface of the opening 24 of the outer can 20. At this time, it is preferable to attach the protective tape 40 around the entire periphery of the opening 24. Next, with insulating plates 16 and 17 arranged above and below the electrode assembly 14, the electrode assembly 14 is housed in the outer can 20. The negative electrode lead 19 is welded to the bottom 21 of the outer can 20, and a grooved portion 23 is formed in the side surface 22 of the outer can 20 by pressing. Next, an appropriate amount of nonaqueous electrolyte is poured into the interior of the outer can 20, and a gasket 34 is placed above the grooved portion 23. Finally, the sealing body 30 is welded to the positive electrode lead 18, and the sealing body 30 is crimped and fixed between the grooved portion 23 and the opening 24 via the gasket 34, thereby producing a nonaqueous electrolyte secondary battery 10 including the protective tape 40.

[0042] As described above, by disposing the protective tape 40 as a protective member having the exposed portion 41 between the opening 24 of the exterior can 20 and the gasket 34, the non-aqueous electrolyte that has leaked out of the battery is prevented from migrating toward the crimped portion 26. As a result, rusting of the exterior can 20 due to contact of the crimped portion 26 with the non-aqueous electrolyte can be prevented.

[0043] Furthermore, providing a protective member between the opening 24 of the outer can 20 and the gasket 34 facilitates improving the sealing performance inside the battery. Furthermore, providing a protective member between the opening 24 of the outer can 20 and the gasket 34 can reduce thermal damage to the gasket 34 and the sealing body 30 when welding the crimped portion 26 during the battery manufacturing process, for example.

[0044] The above-described embodiment can be modified as appropriate without departing from the scope of the present disclosure. For example, in the above-described embodiment, the protective member is a tape attached to the opening 24, but the configuration of the protective member is not limited to this. For example, the protective member may be a sheet-like member that does not have adhesive properties.

[0045] In the above embodiment, the protective tape 40 is disposed between the opening 24 of the gasket 34 and the top surface 34B and side surface 34C of the gasket 34, but the arrangement of the protective tape 40 is not limited to this. For example, the protective tape 40 may be disposed only between the opening 24 and the top surface 34B of the gasket 34, and not between the opening 24 and the side surface 34C of the gasket 34.

[0046] In the above embodiment, the exposed portion 41 extends along the upper surface 34B of the gasket 34, but this is not limiting. For example, as shown in Fig. 4, the exposed portion 41 may extend upward and be disposed so as to cover the radially inner end 26A of the crimped portion 26. In this case, it is possible to prevent leaked nonaqueous electrolyte from coming into contact with the radially inner end 26A of the crimped portion 26.

[0047] In addition to the protective member, a sealant may be disposed between the opening 24 of the outer can 20 and the gasket 34 to improve the airtightness of the outer can 20. Materials that have traditionally been used as sealants can be used as the sealant, including, for example, rubber-based polymers, pitch, asphalt, vinyl-based, silicone-based, acrylic-based, urethane-based, and fluorine-based polymers. The sealant can be prepared, for example, by applying a coating liquid containing the above-mentioned materials to the surface of the protective tape 40 attached to the inner surface of the outer can 20. In other words, the sealant is interposed between the protective tape 40 and the gasket 34.

[0048] The present disclosure is further described by the following embodiments. Aspect 1: A nonaqueous electrolyte secondary battery including an electrode assembly having a positive electrode and a negative electrode, a nonaqueous electrolyte solution, a cylindrical outer can with a bottom that accommodates the electrode assembly and the nonaqueous electrolyte solution, a sealing body that closes an opening of the outer can, an annular gasket that is disposed between the outer can and the sealing body, and a protective member that is disposed between the outer can and the gasket, wherein the outer can has a crimped portion that extends radially inward and crimps and fixes the sealing body, and the protective member has an exposed portion that is disposed radially inward of a radially inner end of the crimped portion. Aspect 2: The nonaqueous electrolyte secondary battery according to Aspect 1, wherein a radially inner end of the exposed portion is disposed radially inward of a radially inner end of the gasket. Aspect 3: The nonaqueous electrolyte secondary battery according to Aspect 1 or 2, wherein a radial length of the exposed portion is 0.10 mm or more. Configuration 4: The nonaqueous electrolyte secondary battery according to any one of Configurations 1 to 3, wherein the exposed portion is provided around the entire circumferential direction of the outer can. Configuration 5: The nonaqueous electrolyte secondary battery according to any one of Configurations 1 to 4, wherein the protective member is a tape and is attached to the inner surface of the outer can. Configuration 6: The nonaqueous electrolyte secondary battery according to any one of Configurations 1 to 5, wherein the protective member has insulating properties.

[0049] REFERENCE SIGNS LIST 10 non-aqueous electrolyte secondary battery, 11 positive electrode, 12 negative electrode, 13 separator, 14 electrode body, 16, 17 insulating plate, 18 positive electrode lead, 19 negative electrode lead, 20 outer can, 21 bottom, 22 side surface, 23 grooved portion, 24 opening, 25 opening side surface, 26 crimped portion, 26A radial inner end, 30 sealing body, 31 internal terminal plate, 31A thick portion, 31B central portion, 31C ventilation hole, 32 insulating member, 32A opening, 32B ventilation hole, 33 external terminal plate, 33A thin portion, 34 gasket, 34A radial inner end, 34B upper surface, 34C side surface, 40 protective tape, 41 exposed portion, 41A radial inner end

Claims

1. A nonaqueous electrolyte secondary battery comprising: an electrode assembly having a positive electrode and a negative electrode; a nonaqueous electrolyte; a cylindrical outer can with a bottom that accommodates the electrode assembly and the nonaqueous electrolyte; a sealing body that closes an opening of the outer can; a ring-shaped gasket that is disposed between the outer can and the sealing body; and a protective member that is disposed between the outer can and the gasket, wherein the outer can has a crimped portion that extends radially inward and crimps and fixes the sealing body, and the protective member has an exposed portion that is disposed radially inward relative to the radial inner end of the crimped portion.

2. The nonaqueous electrolyte secondary battery according to claim 1, wherein a radially inner end of the exposed portion is disposed radially inward of a radially inner end of the gasket.

3. The nonaqueous electrolyte secondary battery according to claim 1, wherein the radial length of the exposed portion is 0.10 mm or more.

4. The nonaqueous electrolyte secondary battery according to claim 1, wherein the exposed portion is provided over the entire circumferential direction of the exterior can.

5. The nonaqueous electrolyte secondary battery according to claim 1, wherein the protective member is a tape attached to the inner surface of the exterior can.

6. The nonaqueous electrolyte secondary battery according to claim 1, wherein the protective member has insulating properties.

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