Cylindrical non-aqueous electrolyte secondary battery

Abstract

A non-aqueous electrolyte secondary battery according to the present invention comprises: an electrode body (14) in which a long positive electrode (11) and a long negative electrode (12) are wound with a separator therebetween; a non-aqueous electrolyte; and an exterior can in which the electrode body and the non-aqueous electrolyte are housed. The negative electrode has: a non-facing part (60) which is on the winding start side from a facing part (59) that faces the winding inner side of a starting end part (11a) of the positive electrode in the winding direction and which is wound so as not to face the positive electrode; and a tab reinforcing plate group (70) which is joined to the non-facing part. The tab reinforcing plate group has a negative electrode tab (21) and reinforcing plates (71, 72). The negative electrode tab and at least one reinforcing plate are disposed so as to be arranged in a prescribed order for a total of 0.75 turns or more from a winding start end of the tab reinforcing plate group, which is an origin of winding, toward the winding end side.

Description

Cylindrical non-aqueous electrolyte secondary battery

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

[0002] A conventional cylindrical nonaqueous electrolyte secondary battery is described in Patent Document 1. In this nonaqueous electrolyte secondary battery, a negative electrode provided with a negative electrode mixture layer has a non-facing portion that does not face a positive electrode at the winding start side of the electrode assembly, and this non-facing portion exists for two or more turns. By providing this non-facing portion, this nonaqueous electrolyte secondary battery suppresses deformation at the winding start side of the electrode assembly.

[0003] JP 2013-137946 A

[0004] In a cylindrical non-aqueous electrolyte secondary battery, if the hollow portion of the electrode body is blocked due to separator melting or the like during abnormal heat generation, it may become impossible to ensure a sufficient exhaust path to the outside via the hollow portion, making it difficult to smoothly exhaust high-temperature gas to the outside. Therefore, there is a need for a cylindrical non-aqueous electrolyte secondary battery that can prevent the hollow portion of the electrode body from being blocked even when abnormal heat generation occurs, and can smoothly exhaust gas to the outside via the hollow portion.

[0005] To address this issue, a possible configuration is to form a non-facing portion at the winding start end of the negative electrode, where the negative electrode is wound so as not to face the positive electrode, and then join the negative electrode tab to the non-facing portion and wind the negative electrode tab 0.75 times or more around the non-facing portion to prevent blockage of the hollow portion of the electrode assembly during abnormal heat generation. However, with this configuration, when the electrode assembly is fabricated, both ends of the negative electrode tab in the winding direction become angular, which may increase the diameter of the wound electrode assembly and make it difficult to fit into the outer can. Furthermore, there is a risk of the electrode plate buckling from the angular portion of the negative electrode tab as the battery is repeatedly charged and discharged.

[0006] An object of the present disclosure is to provide a cylindrical nonaqueous electrolyte secondary battery that can smoothly exhaust gas to the outside through the hollow portion of the electrode body even if abnormal heat is generated, and that can prevent both ends of the negative electrode tab in the winding direction from becoming angular.

[0007] The cylindrical non-aqueous electrolyte secondary battery according to the present disclosure includes an electrode assembly in which a long positive electrode and a long negative electrode are wound with a separator interposed therebetween, a non-aqueous electrolyte, and an outer can accommodating the electrode assembly and the non-aqueous electrolyte, wherein the negative electrode includes a non-facing portion wound from a portion facing the inner side of the winding of a starting end of the positive electrode in the winding direction toward the winding start side in a state not facing the positive electrode, and a tab reinforcing plate group joined to the non-facing portion, the tab reinforcing plate group including a negative electrode tab and at least one reinforcing plate, and wherein the winding start end of the tab reinforcing plate group is set as a starting point of a winding turn, and the negative electrode tab and the at least one reinforcing plate are arranged in a predetermined order from the starting point toward the winding end side for a total of 0.75 turns or more.

[0008] According to the cylindrical nonaqueous electrolyte secondary battery according to the present disclosure, even if abnormal heat is generated, gas can be smoothly discharged to the outside through the hollow portion of the electrode body, and both ends of the negative electrode tab in the winding direction can be prevented from becoming angular.

[0009] 4 is a cross-sectional view in the axial direction of a cylindrical non-aqueous electrolyte secondary battery according to an embodiment of the present disclosure; FIG. 5 is a perspective view of an electrode body of the non-aqueous electrolyte secondary battery; FIG. 6 is a plan view showing the winding structure at the winding start side of the electrode body; FIG. 7 is a view showing the outer surface of a rolled long negative electrode; FIG. 8 is a cross-sectional view taken along the line A-A of FIG. 4; FIG. 9 is a schematic view showing a state in which the periphery of a hollow portion of the electrode body is surrounded by a group of tab reinforcing plates; FIG. 10 is a view corresponding to FIG. 5 of a negative electrode constituting a cylindrical non-aqueous electrolyte secondary battery according to another embodiment; FIG. 11 is a view corresponding to FIG. 10 of a negative electrode constituting a cylindrical non-aqueous electrolyte secondary battery according to another embodiment;

[0010] Below, with reference to the drawings, embodiments of a cylindrical nonaqueous electrolyte secondary battery according to the present disclosure will be described in detail. It is anticipated from the beginning that new embodiments can be constructed by appropriately combining the features of the embodiments and variations described below. In the following embodiments, the same reference numerals are used to designate equivalent components in the drawings, and redundant description will be omitted. Furthermore, multiple drawings include schematic diagrams, and the dimensional ratios of the length, width, height, and other dimensions of each component between different drawings do not necessarily match. Furthermore, in this specification, the side of the sealing body 17 in the axial direction (height direction) of the cylindrical nonaqueous electrolyte secondary battery 10 is referred to as "upper," and the side of the bottom 68 of the outer can 16 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 and not essential. Furthermore, the present disclosure is not limited to the following embodiments and their variations, and various improvements and modifications are possible within the scope of the claims of this application and their equivalents.

[0011] FIG. 1 is an axial cross-sectional view of a cylindrical nonaqueous electrolyte secondary battery 10 according to an embodiment of the present disclosure, and FIG. 2 is a perspective view of an electrode assembly 14 of the nonaqueous electrolyte secondary battery 10. First, the basic configuration of the nonaqueous electrolyte secondary battery 10 will be described using FIGS. 1 and 2 . As shown in FIG. 1 , the nonaqueous electrolyte secondary battery (hereinafter simply referred to as battery) 10 includes a wound electrode assembly 14, a nonaqueous electrolyte (not shown), a cylindrical metal outer can 16 with a bottom that accommodates the electrode assembly 14 and the nonaqueous electrolyte, and a sealing body 17 that closes the opening of the outer can 16. As shown in FIG. 2 , the electrode assembly 14 has a wound structure in which an elongated positive electrode 11 and an elongated negative electrode 12 are wound with an elongated separator 13 interposed therebetween.

[0012] The negative electrode 12 is formed to have dimensions slightly larger than the positive electrode 11 in order to prevent lithium precipitation. 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. Furthermore, the two separators 13 are formed to have dimensions at least slightly larger than the positive electrode 11 and are arranged to sandwich the positive electrode 11, for example. The negative electrode 12 may form the winding start end of the electrode assembly 14. However, generally, the separator 13 extends beyond the winding start end of the negative electrode 12, and the winding start end of the separator 13 becomes the winding start end of the electrode assembly 14.

[0013] The non-aqueous electrolyte includes a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. The non-aqueous solvent may be, for example, an ester, an ether, a nitrile, an amide, or a mixed solvent of two or more of these. The non-aqueous solvent may contain a halogen-substituted compound in which at least a portion of the hydrogen atoms of these solvents are substituted with halogen atoms such as fluorine. The non-aqueous electrolyte is not limited to a liquid electrolyte, but may also be a solid electrolyte using a gel polymer or the like. The electrolyte salt may be LiPF ６ Lithium salts such as

[0014] The positive electrode 11 has a positive electrode core 41 (see FIG. 3 ) and positive electrode mixture layers 42 (see FIG. 3 ) formed on both sides of the positive electrode core 41. The positive electrode core 41 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. The positive electrode mixture layer 42 contains a positive electrode active material, a conductive agent, and a binder. 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 41, drying the coating, and then compressing it to form the positive electrode mixture layers 42 on both sides of the positive electrode core 41.

[0015] 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.

[0016] Examples of the conductive agent contained in the positive electrode mixture layer 42 include carbon materials such as carbon black, acetylene black, ketjen black, and graphite. Examples of the binder contained in the positive electrode mixture layer 42 include fluororesins such as polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVdF), polyacrylonitrile (PAN), polyimide resin, acrylic resin, and polyolefin resin. These resins may be used in combination with cellulose derivatives such as carboxymethyl cellulose (CMC) or a salt thereof, polyethylene oxide (PEO), and the like.

[0017] The negative electrode 12 has a negative electrode core 51 (see FIG. 3 ) and a negative electrode mixture layer 52 (see FIG. 3 ) formed on both sides of the negative electrode core 51. For the negative electrode core 51, 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 can be used. The negative electrode mixture layer 52 contains a negative electrode active material and a binder. The negative electrode 12 can be produced, for example, by applying a negative electrode mixture slurry containing a negative electrode active material and a binder to the negative electrode core 51, drying the coating, and then compressing it to form the negative electrode mixture layer 52 on both sides of the negative electrode core 51.

[0018] 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 52 may contain a silicon (Si)-containing Si material as the negative electrode active material. In this case, the negative electrode mixture layer 52 may contain a silicon (Si)-containing Si material as the negative electrode active material. ｘ (0.5≦x≦1.6) Furthermore, the negative electrode active material may contain a metal other than Si that can be alloyed with lithium, an alloy containing such a metal, a compound containing such a metal, or the like.

[0019] 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 52, 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 52 may also contain, for example, CMC or a salt thereof, polyacrylic acid (PAA) or a salt thereof, polyvinyl alcohol, or the like.

[0020] 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.

[0021] As shown in FIG. 1 , a positive electrode tab 20 is joined to the positive electrode 11, and a negative electrode tab 21 is joined to the winding start side of the negative electrode 12. The negative electrode tab 21 constitutes a tab reinforcing plate group 70, which will be described later. The positive electrode tab 20 is a strip-shaped conductive member. There are no particular limitations on the material of which the positive electrode tab 20 is made. The positive electrode tab 20 is preferably made of a metal containing aluminum as its main component. The negative electrode tab 21 is a strip-shaped conductive member. There are no particular limitations on the material of which the negative electrode tab 21 is made. The negative electrode tab 21 is preferably made of a metal containing nickel or copper as its main component, or a metal containing both nickel and copper.

[0022] The battery 10 has an insulating plate 18 above the electrode body 14 and an insulating plate 19 below the electrode body 14. The positive electrode tab 20 passes through a through-hole in the insulating plate 18 and extends toward the sealing body 17, and the negative electrode tab 21 passes through a through-hole in the insulating plate 19 and extends toward the bottom 68 of the outer can 16. The positive electrode tab 20 is connected to the underside of an internal terminal plate 23 of the sealing body 17 by welding or the like. A terminal cap 27 constituting the top plate of the sealing body 17 is electrically connected to the internal terminal plate 23, and the terminal cap 27 serves as a positive electrode terminal. The negative electrode tab 21 is connected to the inner surface of the bottom 68 of the metal outer can 16 by welding or the like, and the outer can 16 serves as a negative electrode terminal.

[0023] In this embodiment, the positive electrode tab 20 is electrically connected to an intermediate portion, such as the center portion, of the positive electrode core 41 in the winding direction. The negative electrode tab 21 is electrically connected to the winding start end of the negative electrode core 51, and the winding end end of the negative electrode core 51 is abutted against the inner surface of the outer can 16. In this manner, both the winding start end and the winding end end of the negative electrode 12 are electrically connected to the negative electrode terminal, thereby reducing the current path and electrical resistance. However, one negative electrode tab may be electrically connected to the winding start end of the negative electrode core without abutting the winding end end of the negative electrode core against the inner surface of the outer can. Alternatively, the electrode body may have two negative electrode tabs, with one negative electrode tab electrically connected to the winding start end of the negative electrode core and the other negative electrode tab electrically connected to the winding end of the negative electrode core.

[0024] The battery 10 further includes a resin gasket 28 disposed between the exterior can 16 and the sealing body 17. The sealing body 17 is fixed to the opening of the exterior can 16 by crimping via the gasket 28, thereby sealing the internal space of the battery 10. The gasket 28 is sandwiched between the exterior can 16 and the sealing body 17, and insulates the sealing body 17 from the exterior can 16. The gasket 28 serves as a sealing material to maintain airtightness inside the battery and as an insulating material to insulate the exterior can 16 and the sealing body 17.

[0025] The exterior can 16 accommodates the electrode assembly 14 and the non-aqueous electrolyte, and has a shoulder 38, a grooved portion 34, a cylindrical portion 30, and a bottom 68. The grooved portion 34 can be formed, for example, by spinning a portion of the side surface of the exterior can 16 radially inward to form an annular recess radially inward. The shoulder 38 is formed by bending the upper end of the exterior can 16 inward toward the peripheral edge 45 of the sealing body 17 when the sealing body 17 is crimped to the exterior can 16.

[0026] Sealing body 17 has a structure in which, in order from the electrode body 14 side, an internal terminal plate 23, a lower valve body 24, an insulating member 25, an upper valve body 26, and a terminal cap 27 are stacked. Each member constituting sealing body 17 has, for example, a disk or ring shape, and each member except for insulating member 25 is electrically connected to one another. Internal terminal plate 23 has at least one through-hole 23a. Lower valve body 24 and upper valve body 26 are connected at their respective centers, with insulating member 25 interposed between their respective peripheral edges.

[0027] When the battery 10 generates abnormal heat and the internal pressure of the battery 10 rises, the lower valve body 24 deforms and breaks, pushing the upper valve body 26 toward the terminal cap 27, cutting off the current path between the lower valve body 24 and the upper valve body 26. If the internal pressure rises further, the upper valve body 26 breaks and gas is released from the through-hole 27a of the terminal cap 27. This gas release prevents the internal pressure of the battery 10 from rising excessively, which could cause the battery 10 to explode, thereby improving the safety of the battery 10.

[0028] Fig. 3 is a plan view showing the winding structure at the winding start side of the electrode assembly 14. The separator is not shown in Fig. 3. As shown in Fig. 3, the negative electrode 12 includes a non-facing portion 60 wound 0.75 or more times from a portion 59 facing the inner side of the winding of the starting end 11a of the positive electrode 11 in the winding direction to the winding start side so as not to face the positive electrode 11. The non-facing portion 60 is preferably wound 2 or less times, and more preferably 1.5 or less times.

[0029] The negative electrode 12 includes a tab reinforcing plate group 70 joined to the non-facing portion 60. The tab reinforcing plate group 70 is composed of a negative electrode tab 21 and two reinforcing plates 71 and 72. The negative electrode tab 21 and the two reinforcing plates 71 and 72 are joined to the outer winding surface 12a of the negative electrode core 51 that constitutes the innermost periphery of the negative electrode 12. Specifically, the first reinforcing plate 71, the negative electrode tab 21, and the second reinforcing plate 72 are arranged side by side from the winding start end of the negative electrode core 51 toward the winding end end with a gap between them. Each reinforcing plate 71 and 72 is formed into a rectangular metal plate. The winding start end P1 of the first reinforcing plate 71, which is the winding start end of the tab reinforcing plate group 70, is set as the starting point of the winding circumference, and the negative electrode tab 21 and the two reinforcing plates 71 and 72 are arranged side by side in a predetermined order for a total of 0.75 or more turns from the starting point toward the winding end. As a result, as will be described later, in the battery 10, even if abnormal heat is generated, gas can be smoothly exhausted to the outside through the hollow portion 14a of the electrode body 14, and both ends of the negative electrode tab 21 in the winding direction can be prevented from becoming angular. Also, it is preferable that the tab reinforcing plate group 70 is arranged over a range of one turn or less from the winding start end P1 to the winding end end P2. Note that there are no particular restrictions on the order in which the negative electrode tab 21 and the two reinforcing plates 71, 72 are arranged in the winding direction.

[0030] Fig. 4 is a diagram showing the outer surface 12a of the rolled long negative electrode 12. In Fig. 4, the negative electrode mixture layer 52, the reinforcing plates 71, 72, and the negative electrode tab 21 are indicated by a hatched portion, a diagonal grid portion, and a sandy portion, respectively. As shown in Fig. 4, in the width direction of the negative electrode 12 (the direction of arrow β), the length of the negative electrode 12, the length of the overlapping margin of the negative electrode tab 21 with respect to the negative electrode 12, and the lengths of the reinforcing plates 71, 72 are the same.

[0031] In addition, the length of the overlap of the negative electrode tab 21 with respect to the negative electrode 12 and the lengths of the reinforcing plates 71, 72 in the width direction of the negative electrode 12 can also be made smaller relative to the length of the negative electrode 12. In this case, it is preferable that the length of the overlap of the negative electrode tab 21 with respect to the negative electrode 12 and the lengths of the reinforcing plates 71, 72 in the width direction of the negative electrode 12 are the same. For example, when the length of the negative electrode 12 in the width direction of the negative electrode 12 is a [mm], and the length of the overlap of the negative electrode tab 21 with respect to the negative electrode 12 and the lengths of the reinforcing plates 71, 72 are b [mm], it is preferable that b≧0.8a hold.

[0032] FIG. 5 is a cross-sectional view taken along the line A-A in FIG. 4. As shown in FIG. 5, the reinforcing plates 71, 72 and the negative electrode tab 21 can have approximately the same thickness. The reinforcing plates 71, 72 can be formed, for example, from the same metal as the negative electrode tab 21 or the negative electrode core 51. The reinforcing plates 71, 72 may be formed from a material other than metal. For example, the reinforcing plates 71, 72 may be formed from resin. On the other hand, from the viewpoint of ensuring the strength of the tab reinforcing plate group 70 and being able to withstand high temperatures in the event of abnormal heat generation in the battery 10, it is preferable to form the reinforcing plates 71, 72 from metal.

[0033] The battery 10 includes a non-facing portion 60 wound from the facing portion 59 toward the winding start side without facing the positive electrode 11, and a tab reinforcing plate group 70 including a negative electrode tab 21 and two reinforcing plates 71, 72 is joined to the non-facing portion 60. Furthermore, with the winding start end of the tab reinforcing plate group 70 as the starting point of the winding circumference, the negative electrode tab 21 and the two reinforcing plates 71, 72 are arranged in a predetermined order for a total of 0.75 or more turns from the starting point toward the winding end side. Therefore, the periphery of the hollow portion 14a of the electrode body 14 can be surrounded by the highly rigid tab reinforcing plate group 70 for a long distance in the circumferential direction.

[0034] FIG. 6 is a schematic diagram showing the hollow portion of the electrode assembly 14 surrounded by a tab reinforcing plate group 70. Other structures forming the electrode assembly 14 are omitted from FIG. 6 . As shown in FIG. 6 , the highly rigid structure of the tab reinforcing plate group 70 can cover the hollow portion 14a ( FIG. 1 ) of the electrode assembly 14. This prevents the hollow portion 14a from becoming blocked even if the battery 10 generates abnormal heat. As a result, gas is smoothly exhausted to the outside through the hollow portion 14a, improving the safety of the battery 10.

[0035] Furthermore, the tab reinforcing plate group 70 is composed of the negative electrode tab 21 and two reinforcing plates 71, 72 that are separated from each other. Therefore, the tab reinforcing plate group 70 can be curved to follow the curved shape of the non-facing portion 60 when the electrode assembly 14 is fabricated. In this way, compared to when the periphery of the hollow portion 14a is covered only with the negative electrode tab 21, angularity at both ends in the winding direction of the negative electrode tab 21 can be suppressed. Therefore, it is possible to suppress an increase in the diameter of the wound electrode assembly 14, which makes it difficult to insert the electrode assembly 14 into the outer can 16. Furthermore, it is also possible to suppress buckling of the negative electrode 12 originating from angular portions of the negative electrode tab 21 when the battery 10 is repeatedly charged and discharged.

[0036] 7 is a diagram corresponding to FIG. 5 of a negative electrode 40 constituting a battery according to another example of the embodiment. In the configuration of this example, in the negative electrode 40, a tab reinforcing plate group 74 is formed by a negative electrode tab 21 joined to the outer winding surface 40 a of the non-facing portion 60 and a reinforcing plate 75 joined to the inner winding surface 40 b of the non-facing portion 60. The negative electrode tab 21 and the reinforcing plate 75 are arranged side by side in the winding direction so as not to overlap in the thickness direction. The winding start end P1 a of the negative electrode tab 21, which is the winding start end of the tab reinforcing plate group 74, is set as the starting point of the winding turn, and the negative electrode tab 21 and the reinforcing plate 75 are arranged side by side in a predetermined order for a total of 0.75 turns or more from the starting point toward the winding end.

[0037] 1 to 6, in the battery of this example, even if abnormal heat is generated, gas can be smoothly discharged to the outside through the hollow portion of the electrode body, and angularity can be prevented from forming at both ends in the winding direction of the negative electrode tab 21. In this example, the other configurations and functions are the same as those of the configurations of FIGS.

[0038] 8 is a diagram corresponding to FIG. 4 of a negative electrode 80 constituting a battery according to another example of the embodiment. In the configuration of this example, in the negative electrode 80, a tab reinforcing plate group 70a is constituted by the negative electrode tab 21 joined to the winding outer surface 80a of the non-facing portion 60 and two reinforcing plates 71, 72. The first reinforcing plate 71 and the negative electrode tab 21, and the negative electrode tab 21 and the second reinforcing plate 72 are adjacent to each other, respectively. The winding start end P1 of the first reinforcing plate 71, which is the winding start end of the tab reinforcing plate group 70a, is set as the starting point of the winding turn, and the negative electrode tab 21 and the two reinforcing plates 71, 72 are arranged in a predetermined order from the starting point toward the winding end so as to be aligned for a total of 0.75 turns or more.

[0039] In this example, the two reinforcing plates 71, 72 and the negative electrode tab 21 are adjacent to each other and in contact with each other, so that the components of the tab reinforcing plate group 70a can be arranged continuously in the winding direction. This makes it easier to maintain the desired shape of the surrounding shape of the hollow portion of the electrode body, which is formed by the tab reinforcing plate group 70a, even at high temperatures during abnormal heat generation. In this example, the other configurations and functions are the same as those in Figures 1 to 6.

[0040] FIG. 9 is a diagram corresponding to FIG. 5 of a negative electrode 82 constituting a battery according to another example of the embodiment. In this configuration, the negative electrode tab 21 and two reinforcing plates 71a, 72a constitute a tab reinforcing plate group 70b. The thickness of the two reinforcing plates 71a, 72a is smaller than the thickness of the negative electrode tab 21. Specifically, each reinforcing plate 71a, 72a has a thickness that is 10% to 50% of the thickness of the negative electrode tab 21. This configuration allows each reinforcing plate 71a, 72a to be more smoothly curved along the curved shape of the non-facing portion 60 of the negative electrode 82 during fabrication of the electrode assembly. Furthermore, angularity at both ends of each reinforcing plate 71a, 72a in the winding direction can be further suppressed. This further suppresses an increase in the diameter of the wound electrode assembly 14, which makes it difficult to fit the outer can 16. Furthermore, it is possible to further suppress buckling of the negative electrode 12 originating from the angular portions of the reinforcing plates 71 a, 72 a when the battery 10 is repeatedly charged and discharged. In this example, the other configurations and functions are the same as those in FIGS.

[0041] In the configuration of the present disclosure, the tab reinforcing plate groups 70, 70a, 70b, 74 may include a negative electrode tab and at least one reinforcing plate, and may be configured so that the winding start end of the tab reinforcing plate groups 70, 70a, 70b, 74 is the starting point of the winding turn, and the negative electrode tab and the at least one reinforcing plate are arranged in a predetermined order from the starting point toward the winding end side for a total of 0.75 turns or more. For example, the tab reinforcing plate group may be configured to include three or more reinforcing plates.

[0042] DESCRIPTION OF SYMBOLS 10 Battery, 11 Positive electrode, 11a Starting end, 12 Negative electrode, 12a Outer surface of winding, 13 Separator, 14 Electrode body, 14a Hollow portion, 16 Outer can, 17 Sealing body, 18, 19 Insulating plate, 20 Positive electrode tab, 21 Negative electrode tab, 23 Internal terminal plate, 23a Through hole, 24 Lower valve body, 25 Insulating member, 26 Upper valve body, 27 Terminal cap, 27a Through hole, 28 Gasket, 30 Cylindrical portion, 34 Grooved portion, 38 Shoulder portion, 40 Negative electrode, 40a Outer surface of winding, 40b Inner surface of winding, 41 Positive electrode core, 42 Positive electrode mixture layer, 45 Peripheral portion, 51 Negative electrode core, 52 Negative electrode mixture layer, 59 opposing portion, 60 non-facing portion, 68 bottom portion, 70, 70a, 70b tab reinforcing plate group, 71, 71a first reinforcing plate, 72, 72a second reinforcing plate, 74 tab reinforcing plate group, 75 reinforcing plate, 80 negative electrode, 80a outer winding surface, 82 negative electrode, 82a outer winding surface.

Claims

1. A cylindrical non-aqueous electrolyte secondary battery comprising: an electrode assembly in which a long positive electrode and a long negative electrode are wound with a separator interposed therebetween; a non-aqueous electrolyte; and an outer can accommodating the electrode assembly and the non-aqueous electrolyte, wherein the negative electrode includes a non-facing portion wound from a portion facing the inner side of the winding of a starting end of the positive electrode in the winding direction toward the winding start side so as not to face the positive electrode; and a tab reinforcing plate group joined to the non-facing portion, wherein the tab reinforcing plate group includes a negative electrode tab and at least one reinforcing plate, and wherein the winding start end of the tab reinforcing plate group is set as the starting point of a winding cycle, and the negative electrode tab and the at least one reinforcing plate are arranged in a predetermined order from the starting point toward the winding end side for a total of 0.75 cycles.

2. The cylindrical nonaqueous electrolyte secondary battery according to claim 1, wherein the negative electrode tab and the at least one reinforcing plate are adjacent to each other.

3. The cylindrical nonaqueous electrolyte secondary battery according to claim 1, wherein the length of the overlap of the negative electrode tab with respect to the negative electrode in the width direction of the negative electrode is the same as the length of the at least one reinforcing plate.

4. The cylindrical nonaqueous electrolyte secondary battery according to claim 1, wherein the reinforcing plate is made of metal.

5. The cylindrical nonaqueous electrolyte secondary battery according to claim 1, wherein the reinforcing plate has a thickness that is 10% or more and 50% or less of the thickness of the negative electrode tab.

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