Cylindrical battery

Abstract

A cylindrical battery (10) comprises an electrode body (14) obtained by winding an elongated positive electrode (11) and an elongated negative electrode (12) with a separator (13) interposed therebetween. An exposed portion where a negative electrode current collector is exposed is arranged on at least a part of the outermost peripheral surface of the electrode body (14). Double sided tapes (39a, 39b) that fix an outermost peripheral portion (42) of the negative electrode (12) located on the outermost periphery of the electrode body (14) to an inner peripheral side portion (55) facing the inner peripheral surface of the outermost peripheral portion (42) are attached to the inner peripheral surface.

Description

Technical Field

[0001] The present disclosure relates to a cylindrical battery.

Background Art

[0002] Conventionally, as a cylindrical battery, as described in Patent Document 1, there is one provided with an exposed portion where a negative electrode current collector is exposed on the outermost peripheral surface of an electrode body. This cylindrical battery enhances safety by bringing the exposed portion into contact with an outer can and efficiently releasing heat generated during an external short circuit through the exposed portion. Also, in a cylindrical battery, as described in Patent Document 2, there is one in which the end portion of the outer peripheral surface of the outermost peripheral portion existing on the outermost periphery of the electrode body is covered with a tape. This cylindrical battery fixes the outermost periphery of the electrode body to the electrode body with the tape so that the electrode body can be smoothly inserted into the outer can.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In order to smoothly insert the electrode body into the outer can, if the end portion of the electrode body is covered with a tape, it becomes difficult to bring the exposed portion of the negative electrode current collector disposed on the outermost peripheral surface of the electrode body into contact with the outer can, and heat generated in the electrode body cannot be effectively released.

[0005] Therefore, an object of the present disclosure is to provide a cylindrical battery in which insertion of the electrode body into the outer can is easy and heat generated in the electrode body can be effectively radiated.

Means for Solving the Problems

[0006] To solve the above problems, the cylindrical battery according to the present disclosure comprises an electrode body in which a long positive electrode and a long negative electrode are wound with a separator in between, the positive electrode having a long positive electrode current collector and a positive electrode mixture layer provided on at least one side surface of the positive electrode current collector, the negative electrode having a long negative electrode current collector and a negative electrode mixture layer provided on at least one side surface of the negative electrode current collector, an exposed portion in which the negative electrode current collector is exposed is arranged on at least a part of the outermost surface of the electrode body, and fixing means are provided on the inner surface of the outermost portion of the negative electrode located on the outermost surface of the electrode body for fixing the outermost portion of the negative electrode to the inner surface facing that inner surface. [Effects of the Invention]

[0007] According to the cylindrical battery described herein, the electrode body can be smoothly inserted into the outer casing, and the heat generated in the electrode body can be effectively dissipated. [Brief explanation of the drawing]

[0008] [Figure 1] This is an axial cross-sectional view of a cylindrical battery according to one embodiment of the present disclosure. [Figure 2A] This is a schematic diagram showing the outer surface of the end of the negative electrode winding. [Figure 2B] This is a schematic diagram showing the inner surface of the end of the negative electrode winding. [Figure 3] This is a perspective view of the electrode body. [Figure 4] This is a perspective view of the electrode body of Example 2. [Figure 5] This is a perspective view of the electrode body of Example 4. [Figure 6] This is a perspective view of the electrode body of Example 5. [Figure 7] This is a schematic diagram showing the inner circumferential surface of the end of the negative electrode winding in the electrode body of Example 5. [Figure 8] This is a perspective view of the electrode body of the comparative example. [Modes for carrying out the invention]

[0009] Hereinafter, embodiments of the cylindrical battery according to this disclosure will be described in detail with reference to the drawings. The cylindrical battery of this 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. In the following, a non-aqueous electrolyte secondary battery (lithium-ion battery) using a non-aqueous electrolyte will be given as an example of one embodiment of the cylindrical battery 10, but the cylindrical battery of this disclosure is not limited to this.

[0010] Where multiple embodiments and modifications are included below, it is intended from the outset that new embodiments may be constructed by appropriately combining their characteristic features. In the following embodiments, the same reference numerals are used for the same components in the drawings, and redundant explanations are omitted. In addition, multiple drawings include schematic diagrams, and the dimensional ratios such as length, width, and height of each component do not necessarily match between different drawings. In this specification, for the sake of explanation, the side of the cylindrical battery 10 with the sealing body 17 in the axial direction (height direction) is referred to as "upper," and the bottom side of the outer casing 16 in the axial direction is referred to as "lower." Among the components described below, components that are not described in the independent claim indicating the highest-level concept are optional components and are not essential components.

[0011] Figure 1 is an axial cross-sectional view of a cylindrical battery 10 according to one embodiment of the present disclosure. As shown in Figure 1, the cylindrical battery 10 comprises a wound electrode body 14, a non-aqueous electrolyte (not shown), a bottomed cylindrical metal outer casing 16 that houses the electrode body 14 and the non-aqueous electrolyte, and a sealing body 17 that closes the opening of the outer casing 16. The electrode body 14 has a wound structure in which a long positive electrode 11 and a long negative electrode 12 are wound around each other via two long separators 13.

[0012] The negative electrode 12 is formed with a size slightly larger than that of the positive electrode 11 in order to prevent the precipitation of lithium. That is, the negative electrode 12 is formed longer than the positive electrode 11 in the longitudinal direction and the width direction (lateral direction). Also, the two separators 13 are formed with a size at least slightly larger than that of the positive electrode 11 and are arranged, for example, so as to sandwich the positive electrode 11. The negative electrode 12 may constitute the start end of winding of the electrode body 14. However, generally, the separator 13 extends beyond the start side end of the negative electrode 12, and the start side end of the separator 13 becomes the start end of winding of the electrode body 14.

[0013] The non-aqueous electrolyte contains a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. As the non-aqueous solvent, for example, esters, ethers, nitriles, amides, and mixed solvents of two or more of these may be used. The non-aqueous solvent may contain a halogen-substituted product in which at least a part of the hydrogen atoms of these solvents is substituted with a halogen atom such as fluorine. Note that the non-aqueous electrolyte is not limited to a liquid electrolyte and may be a solid electrolyte using a gel-like polymer or the like. As the electrolyte salt, a lithium salt such as LiPF6 is used.

[0014] The positive electrode 11 has a positive electrode current collector and positive electrode mixture layers formed on both surfaces of the positive electrode current collector. As the positive electrode current collector, a metal foil stable within the potential range of the positive electrode 11, such as aluminum or an aluminum alloy, or a film having such a metal disposed on the surface layer can be used. The positive electrode mixture layer contains a positive electrode active material, a conductive agent, and a binder. The positive electrode 11 can be manufactured, for example, by applying a positive electrode mixture slurry containing a positive electrode active material, a conductive agent, a binder, etc. on the positive electrode current collector, drying the coating film, and then compressing it to form the positive electrode mixture layer on both surfaces of the current collector.

[0015] The positive electrode active material is mainly composed of a lithium-containing metal composite oxide. Examples of the 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, W, etc. An example of a preferable 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 active material layer include carbon materials such as carbon black, acetylene black, ketjen black, and graphite. Examples of the binder contained in the positive electrode active material layer 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 its salts, polyethylene oxide (PEO), etc.

[0017] The negative electrode 12 has a negative electrode current collector and negative electrode active material layers formed on both surfaces of the negative electrode current collector. As the negative electrode current collector, a metal foil stable within the potential range of the negative electrode 12, such as copper or a copper alloy, or a film having the metal disposed on the surface layer can be used. The negative electrode active material layer contains a negative electrode active material and a binder. The negative electrode 12 can be manufactured, for example, by applying a negative electrode active material slurry containing a negative electrode active material, a binder, etc. on a negative electrode current collector, drying the coating film, and then compressing it to form negative electrode active material layers on both surfaces of the current collector.

[0018] Generally, a carbon material that reversibly occludes and releases lithium ions is used as the negative electrode active material. Preferred carbon materials are graphite such as flake graphite, massive graphite, and earthy graphite, artificial graphite such as massive artificial graphite, and graphitized mesophase carbon microbeads. The negative electrode active material layer may contain a Si material containing silicon (Si) as the negative electrode active material. Further, as the negative electrode active material, a metal that alloys with lithium other than Si, an alloy containing the metal, a compound containing the metal, etc. may be used.

[0019] For the binder contained in the negative electrode active material layer, fluororesins, PAN, polyimide resin, acrylic resin, polyolefin resin, etc. may be used in the same manner as in the case of the positive electrode 11, but preferably styrene-butadiene rubber (SBR) or its modified product is used. The negative electrode active material layer may contain, for example, in addition to SBR, CMC or its salt, polyacrylic acid (PAA) or its salt, polyvinyl alcohol, etc.

[0020] A porous sheet having ion permeability and insulating properties is used for the separator 13. Specific examples of porous sheets include microporous thin films, woven fabrics, and nonwoven fabrics. The material of the separator 13 is preferably polyethylene, polyolefin resins such as polypropylene, or cellulose. The separator 13 may have either a single-layer structure or a laminated structure. A heat-resistant layer may be formed on the surface of the separator 13.

[0021] As shown in Figure 1, a positive electrode lead 20 is joined to the positive electrode 11, and a negative electrode lead 21 is joined to the beginning of the winding in the longitudinal direction of the negative electrode 12. The cylindrical 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 lead 20 extends towards the sealing body 17 through a through hole in the insulating plate 18, and the negative electrode lead 21 extends towards the bottom 68 of the outer casing 16 through a through hole in the insulating plate 19. The positive electrode lead 20 is connected to the lower surface of the bottom plate 23 of the sealing body 17 by welding or the like. The terminal cap 27 that constitutes the top plate of the sealing body 17 is electrically connected to the bottom plate 23, and the terminal cap 27 becomes the positive electrode terminal. The negative electrode lead 21 is connected to the inner surface of the bottom 68 of the metal outer casing 16 by welding or the like, and the outer casing 16 becomes the negative electrode terminal.

[0022] The cylindrical battery 10 further includes a resin gasket 28 positioned between the outer casing 16 and the sealing body 17. The gasket 28 is sandwiched between the outer casing 16 and the sealing body 17, insulating the sealing body 17 from the outer casing 16. The gasket 28 serves as a sealing material to maintain airtightness inside the battery and as an insulating material to insulate the outer casing 16 from the sealing body 17. The outer casing 16 has an annular grooved portion 34 in a part of its axial direction.

[0023] The grooved portion 34 can be formed, for example, by spinning a part of the side surface radially inward to create a recess on the radially inward side. The outer casing 16 has a bottomed cylindrical portion 30 including the grooved portion 34 and an annular shoulder portion 38. The bottomed cylindrical portion 30 houses the electrode body 14 and the non-aqueous electrolyte, and the shoulder portion 38 is bent radially inward from the opening end of the bottomed cylindrical portion 30 and extends inward. The shoulder portion 38 is formed when the upper end of the outer casing 16 is bent inward and crimped to the peripheral edge 45 of the sealing body 17. The sealing body 17 is crimped and fixed to the outer casing 16 via a gasket 28 between the shoulder portion 38 and the grooved portion 34. In this way, the internal space of the cylindrical battery 10 is sealed.

[0024] The sealing body 17 has a structure in which a bottom plate 23, a lower valve body 24, an insulating member 25, an upper valve body 26, and a terminal cap 27 are stacked in order from the electrode body 14 side. Each component constituting the sealing body 17 has, for example, a disc shape or a ring shape, and each component except the insulating member 25 is electrically connected to one another. The bottom plate 23 has at least one through hole 23a. The lower valve body 24 and the upper valve body 26 are connected at their respective centers, and the insulating member 25 is interposed between their respective peripheral edges.

[0025] If the cylindrical battery 10 overheats and its internal pressure rises, the lower valve body 24 deforms and ruptures, pushing the upper valve body 26 towards the terminal cap 27, thus interrupting 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 ruptures, and gas is released from the through-hole 27a of the terminal cap 27. This release of gas prevents the cylindrical battery 10 from rupturing due to an excessive rise in internal pressure, thereby increasing the safety of the cylindrical battery 10.

[0026] Next, the heat dissipation structure of the cylindrical battery 10 and the fixing structure of the outermost portion 42 of the negative electrode 12 located on the outermost edge of the electrode body 14 will be described. In the cylindrical battery 10, the negative electrode 12 is arranged on the outermost edge of the electrode body 14. Figure 2A is a schematic diagram showing the outer circumferential surface of the end of the winding end of the elongated negative electrode 12, and Figure 2B is a schematic diagram showing the inner circumferential surface of the end of the winding end of the negative electrode 12. As shown in Figure 2A, the end of the winding end of the negative electrode 12 has an exposed portion 33 on its outer circumferential surface where the negative electrode mixture layer 31 is not arranged and the negative electrode current collector 32 is exposed. This exposed portion 33 is located on the outermost surface of the electrode body 14.

[0027] On the other hand, as shown in Figure 2B, double-sided tapes 39a and 39b, as an example of fixing means, are attached to the inner surface of the outermost portion 42 of the negative electrode 12 located on the outermost periphery of the electrode body 14. More specifically, the end of the negative electrode 12 on the winding end side has an exposed portion 37 on its inner surface where the negative electrode mixture layer 35 is not arranged and the negative electrode current collector 32 is exposed. The double-sided tapes 39a and 39b are attached to both ends of the exposed portion 37 in the width direction (width direction of the negative electrode 12). Each double-sided tape 39a and 39b extends along the longitudinal direction of the negative electrode 12.

[0028] Figure 3 is a perspective view of the electrode body 14. As shown in Figure 3, the first double-sided tape 39a is applied to the electrode body 14 in an area of ​​15 mm or less from the upper end in the axial direction, and the second double-sided tape 39b is applied to the electrode body 14 in an area of ​​15 mm or less from the lower end in the axial direction. By applying the double-sided tapes 39a and 39b to the inner surface of the outermost portion 42 of the negative electrode 12 located on the outermost periphery of the electrode body 14, the outermost portion 42 of the negative electrode 12 is fixed to the inner side portion 55 (see Figure 1) facing its inner surface. In this way, the outermost portion 42 of the negative electrode 12 is fixed to the electrode body 14.

[0029] As described above, in the cylindrical battery 10 of this disclosure, an exposed portion 33 is provided on at least a part of the outermost surface of the electrode body 14 in which the negative electrode current collector 32 is exposed. Furthermore, the cylindrical battery 10 is provided with double-sided tapes 39a and 39b on the inner surface of the outermost portion 42 of the negative electrode 12 located on the outermost surface of the electrode body 14, which are used to fix the outermost portion 42 to the inner side portion 55 facing that inner surface.

[0030] Since there is no tape on the outer surface of the electrode body 14 that holds the winding structure of the electrode body 14, the exposed portion 33 located on the outermost surface of the electrode body 14 can be brought into close contact with the inner surface of the outer casing 16. Therefore, the heat generated in the electrode body 14 during charging and discharging of the cylindrical battery 10 can be efficiently dissipated through the exposed portion 33, and the electrode body 14 can be efficiently cooled. Consequently, thermal degradation of the electrode body 14 can be suppressed, and the capacity retention rate when charging and discharging is repeated can be increased.

[0031] Furthermore, when the outer casing 16 and the exposed portion 33 come into contact, the end of the long negative electrode current collector 32 at the winding end is electrically connected to the outer casing 16, which serves as the negative electrode terminal. Therefore, the winding start end of the long negative electrode current collector 32 can be electrically connected to the outer casing 16 using the negative electrode lead 21, and the winding end end of the negative electrode current collector 32 can also be electrically connected to the outer casing 16. This reduces the electrical resistance of the path from the negative electrode 12 to the outer casing 16, thereby reducing power loss.

[0032] Furthermore, the outermost portion 42 of the negative electrode 12, located on the outermost periphery of the electrode body 14, can be fixed to the inner circumferential portion 55 facing its inner circumferential surface by the double-sided tapes 39a and 39b, thereby maintaining the winding structure of the electrode body 14. As a result, the electrode body 14 can be smoothly inserted into the outer casing 16, and the mass production efficiency of the cylindrical battery 10 can also be improved.

[0033] When inserting the electrode body into the outer casing, the outermost part of the electrode body is prone to snagging on the casing at both axial ends. In contrast, as shown in the example in Figure 3, if at least a portion of the outermost part 42 of the electrode body 14 within 15 mm from both axial ends is fixed with double-sided tape 39a, 39b, snagging of the outermost part 42 on the casing 16 can be greatly suppressed. Therefore, the electrode body 14 can be inserted into the casing 16 more smoothly, further improving the mass production efficiency of the cylindrical battery 10.

[0034] In addition, in the cylindrical battery of this disclosure, the negative electrode 12 may be electrically connected to the outer casing 16 by contact only between the outer casing 16 and the exposed portion 33, and the negative electrode lead may be omitted. Alternatively, as in the cylindrical batteries of Examples 1 to 5 described below, the negative electrode lead may be joined to the exposed portion of the negative electrode current collector provided at the end of the winding on the longitudinal side of the negative electrode, and the negative electrode lead may be joined to the outer casing. [Examples]

[0035] [Example 1] (Fabrication of the positive electrode) 100 parts by mass of LiNi 0.88 Co 0.09 Al 0.03 O2, 1 part by mass of acetylene black, and 0.9 parts by mass of polyvinylidene fluoride were mixed, and an appropriate amount of N-methyl-2-pyrrolidone was added to prepare a positive electrode mixture slurry. Next, the positive electrode mixture slurry was applied to both sides of a long positive electrode current collector made of 15 μm thick aluminum foil, and the coating was dried. After the dried coating was compressed using a roller, it was cut to a predetermined electrode size, and a positive electrode (thickness 0.144 mm, width 62.6 mm, length 861 mm) was fabricated with positive electrode mixture layers formed on both sides of the positive electrode current collector. An exposed section was provided in the longitudinal center of the positive electrode where the positive electrode mixture layer was absent and the positive electrode current collector was exposed, and an aluminum positive electrode lead was welded to the exposed section.

[0036] (Fabrication of the negative electrode) A negative electrode mixture slurry was prepared by mixing 95 parts by mass of graphite powder, 5 parts by mass of Si oxide, 1 part by mass of carboxymethylcellulose sodium, and 1 part by mass of styrene-butadiene rubber, and adding an appropriate amount of water. Next, the negative electrode mixture slurry was applied to both sides of a long negative electrode current collector made of 8 μm thick copper foil, and the coating was dried. After compressing the dried coating using a roller, it was cut to a predetermined electrode size, and a negative electrode (thickness 0.160 mm, width 64.2 mm, length 959 mm) was fabricated with negative electrode mixture layers formed on both sides of the negative electrode current collector. An exposed portion was provided at one end of the negative electrode in the longitudinal direction (the end portion located on the winding end side of the electrode body) where the negative electrode mixture layer was absent and the negative electrode current collector was exposed, and a nickel negative electrode lead was welded to the exposed portion.

[0037] (Fabrication of wound electrode bodies) A wound electrode body was fabricated by winding the above-mentioned positive electrode and negative electrode via a separator made of a polyethylene microporous membrane. The outermost surface of the electrode body is an exposed area where the negative electrode current collector is exposed across its entire surface. A double-sided tape with a width of 9 mm, a thickness of 15 μm, and a length of 62 mm was applied to the inner surface of the outermost part of the negative electrode, which is located on the outermost surface of the electrode body, in a range of 15 mm or less from both ends in the axial direction, similar to the electrode body 14 shown in Figure 3, to maintain the wound structure of the electrode body. The double-sided tape used was a polypropylene tape with a thickness of 30 μm, a width (length along the vertical direction of the electrode body) of 9 mm, and a length (length along the circumferential direction of the electrode body) of 6 mm, with a polypropylene base layer.

[0038] (Preparation of non-aqueous electrolyte) Ethylene carbonate (EC) and dimethyl carbonate (DMC) were mixed in a volume ratio of EC:DMC = 3:7. 5% by mass of vinylene carbonate was added to this mixed solvent, and LiPF6 was dissolved at a concentration of 1.5 mol / L to prepare a non-aqueous electrolyte.

[0039] (Manufacturing of cylindrical batteries) Insulating plates were placed above and below the electrode body, the negative electrode lead was welded to the outer casing, and the positive electrode lead was welded to a sealing plate with an internal pressure-operated safety valve, and the battery was then housed inside the battery case. Subsequently, a non-aqueous electrolyte was injected into the battery case using a reduced pressure method. Finally, the sealing plate was crimped and fixed to the open end of the outer casing via a gasket to create a cylindrical battery, which is a non-aqueous electrolyte secondary battery. The initial capacity of the fabricated cylindrical battery was 4600mAh.

[0040] [Example 2] As shown in Figure 4, a cylindrical battery according to Example 2 was manufactured in the same manner as in Example 1, except that the electrode body 114 used had double-sided tapes 139a and 139b, whose length was changed to 10 mm, attached from the end to the starting end of the inner surface of the outermost part of the negative electrode, which is placed on the outermost circumference of the electrode body 114.

[0041] [Example 3] A cylindrical battery according to Example 3 was fabricated in the same manner as in Example 2, except that the electrode body used had double-sided tape attached from a position 20 mm away from the end of the outermost periphery of the negative electrode toward the starting end.

[0042] [Example 4] As shown in Figure 5, a cylindrical battery according to Example 4 was manufactured in the same manner as in Example 2, except that the electrode body 214 was made in which double-sided tape 239 was attached only to one location in the axial direction center of the inner surface of the outermost part, rather than to both ends in the axial direction.

[0043] [Example 5] As shown in Figures 6 and 7, a cylindrical battery according to Example 5 was manufactured in the same manner as in Example 1, except that an electrode body 314 was used in which double-sided tape 339 with a width of 62 mm was attached to substantially the entire inner surface of the outermost part of the negative electrode 312, which is positioned on the outermost periphery of the electrode body 314.

[0044] [Comparative Example] As shown in Figure 8, a cylindrical battery according to the comparative example was manufactured in the same manner as in Example 1, except that the electrode body 414 was not fitted with double-sided tape on the inner surface of the outermost part, and single-sided polypropylene (PP) tapes 439a and 439b, with a width of 9 mm, a thickness of 3 mm, and a length of 62 mm, were fitted to both axial ends of the outermost surface of the outermost part.

[0045] [Evaluation of heat dissipation] Each fabricated cylindrical battery was charged at a constant current of 1380mA (0.3It) in a 25°C environment until it reached 4.2V, after which constant voltage charging was performed with a termination current of 92mA at 4.2V. After a 20-minute rest period, constant current discharge was performed at a discharge current of 4600mA (1It), and the maximum temperature of the cylindrical battery during discharge was detected. In this way, the heat dissipation performance of the cylindrical battery was evaluated using the maximum temperature during discharge as an indicator. The evaluation results are shown in Table 1.

[0046] [Table 1]

[0047] As shown in Table 1, the cylindrical batteries of Examples 1 to 5 exhibit lower maximum discharge temperatures and superior heat dissipation compared to the cylindrical batteries of the comparative examples. Therefore, the cylindrical batteries of this disclosure allow for smooth insertion of the electrode body into the outer casing and effectively dissipate the heat generated by the electrode body.

[0048] The reason why the maximum discharge temperature of the cylindrical batteries in Examples 1 to 5 is low is thought to be that, unlike the cylindrical battery in the comparative example, the tape used as a fixing means is not exposed on the outer surface of the outermost part, so there are no obstacles to heat conduction from the exposed part of the negative electrode current collector to the outer casing, and the exposed part of the negative electrode current collector and the outer casing can be in uniform contact.

[0049] Furthermore, the reason why the cylindrical battery in Example 5 had the lowest maximum discharge temperature is thought to be because double-sided tape was applied to almost the entire inner surface of the outermost part of the negative electrode, resulting in more uniform and close contact between the exposed part of the negative electrode current collector and the outer casing.

[0050] This disclosure is not limited to the embodiments and their modifications, and various improvements and modifications are possible within the scope of the claims of this application and their equivalents.

[0051] For example, in the above embodiment, a case was described in which a positive electrode mixture layer is provided on both sides of the positive electrode current collector and a negative electrode mixture layer is provided on both sides of the negative electrode current collector. However, a positive electrode mixture layer may be provided on only one side of the positive electrode current collector and a negative electrode mixture layer may be provided on only one side of the negative electrode current collector.

[0052] Furthermore, a case has been described in which the inner surface of the outermost portion 42 of the negative electrode 12 located on the outermost periphery of the electrode body 14 is fixed to the inner side portion 55 facing the outermost portion 42 using double-sided tapes 39a, 39b, 139a, 139b, 239, and 339. However, an adhesive may be used instead of double-sided tape as such a fixing means. Here, the adhesive includes forms that solidify by drying or chemical reaction, as well as other forms, such as forms that do not solidify. Any adhesive is acceptable as long as it can fix the outermost portion of the negative electrode located on the outermost periphery of the electrode body to the inner side portion facing its inner surface. Examples of adhesives include acrylic adhesives, silicone adhesives, or rubber adhesives. The fixing means is not limited to double-sided tape and adhesives, and may consist of any member that can fix the outermost portion of the negative electrode located on the outermost periphery of the electrode body to the inner side portion facing its inner surface. [Explanation of Symbols]

[0053] 10 Cylindrical battery, 11 Positive electrode, 12, 312 Negative electrode, 13 Separator, 14, 114, 214, 314 Electrode body, 16 Outer can, 17 Sealing body, 18, 19 Insulating plate, 20 Positive electrode lead, 21 Negative electrode lead, 27 Terminal cap, 28 Gasket, 30 Bottomed cylindrical part, 31 Negative electrode mixture layer, 32, 332 Negative electrode current collector, 33, 333 Exposed part, 34 Grooved part, 35 Negative electrode mixture layer, 37 Exposed part, 39a First double-sided tape, 39b Second double-sided tape, 42 Outermost part, 55 Inner circumference part, 139a, 139b, 239, 339 Double-sided tape.

Claims

1. The electrode body comprises a long positive electrode and a long negative electrode wound around a separator, The positive electrode comprises a long positive electrode current collector and a positive electrode mixture layer provided on at least one side surface of the positive electrode current collector. The negative electrode comprises a long negative electrode current collector and a negative electrode mixture layer provided on at least one side surface of the negative electrode current collector. An exposed portion is provided on at least a part of the outermost surface of the electrode body, in which the negative electrode current collector is exposed. A fixing means is provided on the inner circumferential surface of the outermost portion of the negative electrode located at the outermost circumferential surface of the electrode body, for fixing the outermost portion to the inner circumferential side portion facing the inner circumferential surface. A cylindrical battery in which there is no portion covered with tape on the outermost side of the outermost part.

2. The cylindrical battery according to claim 1, wherein the fixing means is double-sided tape.

3. The cylindrical battery according to claim 1, wherein the fixing means is an adhesive.

4. The cylindrical battery according to any one of claims 1 to 3, wherein the fixing means is provided on at least a portion of the inner surface of the outermost outer portion, within a range of 15 mm or less from both ends in the axial direction of the electrode body.

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