Cylindrical battery

Abstract

This battery (10) comprises: an electrode body (14) in which a positive electrode (11) and a negative electrode (12) are wound with a separator (13) interposed therebetween; an outer can (16) that accommodates the electrode body (14); a sealing body (17) that closes an opening of the outer can (16) with a gasket (28) interposed therebetween; an upper insulating plate (18) disposed on an end surface of the electrode body (14) on the sealing body (17) side; and a negative electrode lead (21) joined to the negative electrode (12) and including an extension part extending from the end surface. The extension part is joined to a side surface of the outer can (16) at a position closer to the opening than a position facing the upper insulating plate (18).

Description

Cylindrical battery

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

[0002] Conventionally, as a cylindrical battery, there is one described in Patent Document 1. This cylindrical battery includes an electrode body in which a positive electrode and a negative electrode are wound with a separator interposed therebetween, a bottomed cylindrical outer can that houses the electrode body, and a sealing body that is caulked and fixed to the opening of the outer can via a gasket. At the middle part in the longitudinal direction of the positive electrode, a positive electrode core body exposed portion is provided so as to be sandwiched between the positive electrode mixture layers in the longitudinal direction of the positive electrode. One end of the positive electrode lead is joined to the positive electrode core body exposed portion, and the other end of the positive electrode lead is joined to the inner surface of the sealing body. Also, one end of the negative electrode lead is joined to the end portion on the winding end side of the negative electrode, and the other end of the negative electrode lead is joined to the inner surface of the bottom of the outer can.

[0003] Japanese Patent Laid-Open No. 10-255755

[0004] The other end of the negative electrode lead is generally joined to the inner surface of the bottom of the outer can by resistance welding. Specifically, with the other end of the negative electrode lead pressed against the bottom side of the outer can by a welding rod (one electrode) inserted into the hollow portion of the electrode body and held between the one electrode and the other electrode in contact with the outer surface of the bottom of the outer can, a current is passed between the pair of electrodes, whereby the other end of the negative electrode lead is welded to the bottom of the outer can.

[0005] During the above-mentioned resistance welding, spatter may occur. However, since the joint portion is difficult to visually recognize from the opening side of the outer can during welding, it is difficult to identify the position of the generated spatter, and it is not easy to remove the spatter from the battery. If foreign matter due to spatter混入 the battery, there is a risk of causing a deterioration in the quality of the battery. Therefore, an object of the present disclosure is to provide a high-quality cylindrical battery in which the混入 of foreign matter is suppressed.

[0006] To solve the above problems, the cylindrical battery according to the present disclosure comprises an electrode body in which a first electrode and a second electrode are wound with a separator between them; an outer can for housing the electrode body; a sealing body that closes the opening of the outer can with a gasket; an insulating plate disposed on the end face of the electrode body on the side of the sealing body; and an electrode lead that is joined to the first electrode and includes an extension extending from the end face, wherein the extension is joined to the outer can at a position on the side surface of the outer can that is closer to the opening than to the position facing the insulating plate.

[0007] According to the cylindrical battery described herein, the inclusion of foreign matter can be suppressed, and quality can be improved.

[0008] This is an axial cross-sectional view of a cylindrical battery according to one embodiment of the present disclosure. This is a schematic cross-sectional view showing a state during the manufacturing process of the cylindrical battery. This is a diagram showing the connection structure of cylindrical batteries connected to each other within a battery pack, with the outer casing shoulders serving as negative electrode terminals. This is an axial cross-sectional view of a modified cylindrical battery corresponding to Figure 1.

[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. Furthermore, the cylindrical battery of this disclosure may be a battery using an aqueous electrolyte or a battery using a non-aqueous electrolyte. In the following, a cylindrical lithium-ion secondary 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] It is intended from the outset that new embodiments can be constructed by appropriately combining the characteristic features of the embodiments and modifications described below. 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, 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 side of the outer casing 16 with the bottom 31 in the axial direction is referred to as "lower." Furthermore, 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 (hereinafter simply referred to as "battery") 10 comprises an electrode body 14, a non-aqueous electrolyte (not shown), a bottomed cylindrical 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 via a gasket 28. The gasket 28 is made of, for example, polyolefin. The outer casing may have openings at both ends in the axial direction. In that case, the cylindrical battery has a configuration in which the upper and lower openings of the outer casing are closed by the sealing body.

[0012] The electrode body 14 includes a long positive electrode 11, a long negative electrode 12, and two long separators 13 interposed between the positive electrode 11 and the negative electrode 12, and has a wound structure in which the positive electrode 11 and the negative electrode 12 are wound along the longitudinal direction via the separators 13. The negative electrode 12 is formed to be slightly larger in dimensions than the positive electrode 11 in order to prevent lithium deposition. The negative electrode 12 is formed to be longer than the positive electrode 11 in the winding direction and in the axial direction. The two separators 13 are formed to be slightly larger in dimensions than the positive electrode 11 and are arranged to sandwich the positive electrode 11. The separators 13 protrude above and below the positive electrode 11 and the negative electrode 12.

[0013] Non-aqueous electrolytes are ionic conductive (e.g., lithium ion conductive). Non-aqueous electrolytes may be liquid electrolytes (electrolytes) or solid electrolytes. Liquid electrolytes (electrolytes) contain a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. Examples of non-aqueous solvents include esters, ethers, nitriles, amides, and mixtures of two or more of these. Examples of non-aqueous solvents include ethylene carbonate (EC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and mixtures thereof. Non-aqueous solvents may contain halogen-substituted solvents (e.g., fluoroethylene carbonate) in which at least some of the hydrogen atoms of these solvents are replaced with halogen atoms such as fluorine. Examples of electrolyte salts include LiPF4. ６ Lithium salts such as these are used.

[0014] As solid electrolytes, for example, solid or gel-like polymer electrolytes, inorganic solid electrolytes, etc., are used. Polymer electrolytes include, for example, a lithium salt and a matrix polymer, or a non-aqueous solvent, a lithium salt and a matrix polymer. As matrix polymers, for example, polymer materials that absorb non-aqueous solvents and gel are used. As polymer materials, for example, fluororesins, acrylic resins, polyether resins, etc., are used. As inorganic solid electrolytes, for example, materials known for all-solid-state lithium-ion secondary batteries, etc. (for example, oxide-based solid electrolytes, sulfide-based solid electrolytes, halide-based solid electrolytes, etc.) are used.

[0015] The positive electrode 11 has a positive electrode core and a positive electrode mixture layer formed on both sides of the positive electrode core. The positive electrode core can be made of a metal foil that is stable within the potential range of the positive electrode 11, such as aluminum or an aluminum alloy, or a film with the metal arranged on its surface. The positive electrode mixture layer contains a positive electrode active material, a conductive agent, and a binder. The positive electrode 11 is manufactured, for example, by applying a positive electrode mixture slurry containing a positive electrode active material, a conductive agent, and a binder onto the positive electrode core, drying the coating, and then compressing it to form the positive electrode mixture layer on both sides of the positive electrode core.

[0016] 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. A preferred example of a lithium-containing metal composite oxide is a composite oxide containing at least one of Ni, Co, Mn, and Al.

[0017] Examples of conductive agents included in the positive electrode mixture layer include carbon black such as acetylene black and Ketjen black, and carbon materials such as graphite. Examples of binders included in the positive electrode mixture layer include fluororesins such as polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVdF), polyacrylonitrile (PAN), polyimide resins, acrylic resins, and polyolefin resins. These resins may be used in combination with cellulose derivatives such as carboxymethylcellulose (CMC) or its salts, polyethylene oxide (PEO), etc.

[0018] The negative electrode 12 comprises a negative electrode core and negative electrode mixture layers formed on both sides of the negative electrode core. The negative electrode core can be made of a metal foil that is stable within the potential range of the negative electrode 12, such as copper or a copper alloy, or a film with the metal arranged on its surface. The negative electrode mixture layers contain a negative electrode active material and a binder. The negative electrode 12 is manufactured, for example, by applying a negative electrode mixture slurry containing the negative electrode active material and binder onto the negative electrode core, drying the coating, and then compressing it to form the negative electrode mixture layers on both sides of the negative electrode core.

[0019] Generally, carbon materials that reversibly intercept and release lithium ions are used as the negative electrode active material. Preferred carbon materials are graphite such as natural graphite such as flake graphite, lump graphite, and clay graphite, and artificial graphite such as lump graphite and graphitized mesophase carbon microbeads. The negative electrode mixture layer may contain silicon (Si) material as the negative electrode active material. In addition, metals that alloy with lithium other than Si, alloys containing such metals, compounds containing such metals, etc., may be used as the negative electrode active material.

[0020] The binder included in the negative electrode mixture layer may be fluororesin, PAN, polyimide resin, acrylic resin, polyolefin resin, etc., as in the case of the positive electrode 11, but preferably styrene-butadiene rubber (SBR) or a modified version thereof is used. In addition to SBR, the negative electrode mixture layer may also contain, for example, CMC or a salt thereof, polyacrylic acid (PAA) or a salt thereof, polyvinyl alcohol, etc.

[0021] 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 or the like may be formed on the surface of the separator 13.

[0022] The outer can 16 is generally made of a metal mainly composed of iron, for example, a material made of iron plated with nickel. The outer can 16 may also be made of a metal mainly composed of aluminum or the like. The outer can 16 has a cylindrical portion 39 and a bottom portion 31, and the cylindrical portion 39 includes an annular grooved portion 22 and an annular shoulder portion 29. The grooved portion 22 is formed by spinning a part of the cylindrical portion 39 to create a recess radially inward along the entire circumference. The shoulder portion 29 is formed when the upper end of the cylindrical portion 39 is bent radially inward and crimped to the peripheral edge portion 33 of the sealing body 17, and extends radially inward at the upper end of the cylindrical portion 39.

[0023] The sealing body 17 is fixed to the outer can 16 by crimping, with a gasket 28 sandwiched between the shoulder portion 29 and the grooved portion 22. The grooved portion 22 is formed at a predetermined distance from the upper end of the outer can 16. The predetermined length is, for example, 1 to 20% of the axial length of the outer can 16. The gasket 28 is strongly compressed by the shoulder portion 29, and a portion of the gasket 28 protrudes radially inward from between the shoulder portion 29 and the sealing body 17.

[0024] The electrode body 14 is positioned below the grooved portion 22 inside the outer can 16. An annular upper insulating plate 18 is positioned above the electrode body 14 and below the grooved portion 22, and a disc-shaped lower insulating plate 19 is positioned below the electrode body 14. In the example shown in Figure 1, the positive electrode lead 20 attached to the positive electrode 11 extends through a through hole in the upper insulating plate 18 towards the sealing body 17 and is joined to the lower surface of the sealing body 17. On the other hand, the negative electrode lead 21 attached to the negative electrode 12 extends outside the upper insulating plate 18 towards the grooved portion 22 of the outer can 16 and is joined to the lower surface 22a of the grooved portion 22 (the surface of the grooved portion 22 facing the electrode body 14).

[0025] The negative electrode 12 constitutes the first electrode, and the positive electrode 11 constitutes the second electrode. The negative electrode lead 21 constitutes an electrode lead that is joined to the first electrode. In this embodiment, a separator 13 is arranged on the outermost circumference of the electrode body 14, the positive electrode lead 20 is joined to an intermediate part of the positive electrode 11, such as the center in the longitudinal direction of the positive electrode, and the negative electrode lead 21 is joined to the outermost circumference of the negative electrode 12. However, the negative electrode 12 may be arranged on the outermost circumference of the electrode body instead of the separator 13. In this case, at least a part of the negative electrode 12 may be in contact with the inner surface of the outer casing. The negative electrode lead 21 is joined to the exposed portion of the negative electrode core provided on the negative electrode 12, but it may be joined to either the outer surface or the inner surface of the winding of the negative electrode 12.

[0026] The sealing body 17 has a structure in which a terminal plate 23, a lower valve body 24, an insulating plate 25, an upper valve body 26, and a terminal cap 27 are stacked in this 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 plate 25 is electrically connected to one another. The terminal cap 27 has a convex shape with its radial center portion protruding outward. The convex portion 27a of the terminal cap 27 includes a flat top surface and an annular slanted surface surrounding the top surface. One or more ventilation holes 27b are formed in the top surface. The convex portion of the terminal cap 27 may have a cylindrical portion instead of the annular slanted surface.

[0027] The lower valve body 24, the insulating plate 25, and the upper valve body 26 constitute a current interruption mechanism. The lower valve body 24 and the upper valve body 26 are connected at their respective central portions, with the insulating plate 25 interposed between their respective peripheral portions. When the battery 10 overheats abnormally and the internal pressure of the battery rises, the lower valve body 24 deforms and breaks, pushing the upper valve body 26 towards the terminal cap 27, thereby 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 breaks, and gas is discharged from the vent hole 27b of the terminal cap 27.

[0028] In this embodiment, the upper end of the positive electrode lead 20 is connected to the lower surface of the terminal plate 23 by welding or ultrasonic welding, and the terminal cap 27, which is the top plate of the sealing body 17 electrically connected to the terminal plate 23, becomes the positive electrode terminal. The negative electrode lead 21 is connected to the lower surface 22a of the grooved portion 22 by welding or ultrasonic welding, and the outer casing 16 becomes the negative electrode terminal. The description above has shown a case where the sealing body 17 has a laminated structure including two rupture plates (lower valve body 24 and upper valve body 26) and a convex terminal cap 27 that covers the two rupture plates. However, the sealing body may consist only of rupture plates, or it may have a structure in which an internal terminal plate, an insulating plate, and a rupture plate are laminated in order from the electrode body side. Alternatively, the sealing body may not have rupture plates, and the bottom of the outer casing may have a thin, easily breakable portion that breaks when the battery overheats abnormally.

[0029] The battery 10 is manufactured, for example, as follows. Figure 2 is a schematic cross-sectional view showing one state during the manufacturing process of the battery 10. Referring to Figure 2, first, an electrode body 14 is prepared in which a positive electrode lead 20 is joined to an intermediate part of the positive electrode 11, such as the central part in the longitudinal direction of the positive electrode, and a negative electrode lead 21 is joined to the outermost circumference of the negative electrode 12. The positive electrode lead 20 has a positive electrode extension portion 20a that extends from the upper end face of the electrode body 14, and the negative electrode lead 21 has a negative electrode extension portion 21a that extends from the upper end face of the electrode body 14.

[0030] Next, the disc-shaped lower insulating plate 19 is inserted from the opening side of the bottomed cylindrical outer can 16, and then the electrode body 14 is inserted into the outer can 16. After that, the upper insulating plate 18 is placed on the end face of the electrode body 14. At this time, the negative electrode extension portion 21a of the negative electrode lead 21 is positioned to pass outside the upper insulating plate 18, and the positive electrode extension portion 20a of the positive electrode lead 20 is positioned to pass through the through hole 18a. Alternatively, the upper insulating plate 18 may be assembled to the end face of the electrode body 14 before inserting the electrode body 14 into the outer can 16.

[0031] Next, the portion of the negative electrode extension 21a that is above the upper insulating plate 18 is joined to the inner circumferential surface of the cylindrical portion 39 of the outer can 16 by resistance welding, laser welding, or the like. Subsequently, a portion of the outer can 16 located above the upper insulating plate 18 is spun to create a groove 22 (see Figure 1) by recessing it radially inward along the entire circumference. After the formation of the groove 22, the joint portion of the negative electrode lead 21 to the outer can 16 is located on the lower surface 22a (see Figure 1) of the groove 22.

[0032] Subsequently, an annular gasket 28 is inserted into the outer casing 16, and the tip of the positive electrode extension 20a is welded to the lower surface of the sealing body 17 (see Figure 1) by laser welding or the like. Next, the electrolyte is placed inside the outer casing 16, and then the sealing body 17 is placed on the upper side of the grooved portion 22 inside the outer casing 16. Finally, the opening of the outer casing is folded radially inward and crimped to the periphery of the sealing body 17, and the sealing body 17 is sandwiched between the shoulder portion 29 and the grooved portion 22 via the gasket 28, thereby manufacturing the battery 10.

[0033] Next, the effects of the battery 10 of the above embodiment will be explained. As described above, when the other end of the negative electrode lead is joined to the inner surface of the bottom of the outer casing by resistance welding, the other end of the negative electrode lead is pressed towards the bottom of the outer casing with a welding rod (one electrode) inserted through the hollow part of the electrode body, and while the other electrode is sandwiched between the one electrode and the other electrode, current is passed between the pair of electrodes, thereby welding the other end of the negative electrode lead to the bottom of the outer casing.

[0034] During the resistance welding process described above, spatter may occur. However, because the joint is difficult to see from the opening of the outer casing during welding, it is difficult to pinpoint the location of the spatter, making it difficult to remove it from the battery. If foreign matter caused by spatter enters the battery, it may lead to a decrease in quality.

[0035] In contrast, in the battery 10 of this disclosure, the negative electrode extension portion 21a extending from the axial sealing body 17 side of the electrode body 14 is joined to the side surface of the outer casing 16 on the axial sealing body 17 side of the upper insulating plate 18. Therefore, as shown in Figure 2, the joining of the negative electrode lead 21 to the side surface of the outer casing 16 can be performed above the upper insulating plate 18 in a well-visible manner.

[0036] As a result, even if spatter occurs when joining the negative electrode lead 21 to the side of the outer casing 16, the location of the spatter can be easily identified. Moreover, since the spatter can be received on the upper surface of the upper insulating plate 18, foreign matter caused by spatter can be easily removed from the upper surface of the upper insulating plate 18. Therefore, a high-quality battery 10 with suppressed contamination of foreign matter can be realized. In addition, since the joining of the negative electrode lead 21 to the side of the outer casing 16 can be performed in a wide space above the upper insulating plate 18, the degree of freedom in selecting the joining method can be greatly increased.

[0037] Furthermore, as shown in Figure 3, when manufacturing a battery pack by electrically connecting multiple batteries 10 with a current collector 85, the sealing body 17 may be used as the positive terminal and the shoulder portion 29 of the outer casing 16 may be used as the negative terminal. In such cases, compared to a cylindrical battery in which the negative lead is joined to the bottom of the outer casing, the current path from the point where the negative lead 21 is joined to the outer casing 16 to the negative terminal is shortened in the battery 10 of this disclosure. Therefore, the electrical resistance of the battery 10 when the shoulder portion 29 of the outer casing 16 is used as the negative terminal can be reduced compared to when the negative lead is joined to the bottom of the outer casing.

[0038] In order to suppress short circuits in the portions of the positive lead 20 and the negative lead 21 that extend from the upper end faces of the electrode bodies 14, it is preferable that the negative lead is joined to the outermost circumference of the negative electrode 12, and that the upper end of the negative lead 21 is joined to the lower surface 22a of the grooved portion 22.

[0039] This disclosure is not limited to the embodiments and their variations, and various improvements and modifications are possible within the scope of the claims of this application and their equivalents.

[0040] Figure 4 is an axial cross-sectional view of a modified cylindrical battery 110 corresponding to Figure 1. As shown in Figure 4, when the radial length from the innermost to the outermost circumference of the negative electrode 12 is L, the lower side of the negative electrode lead 121, whose upper end portion 121a is joined to the lower surface 22a of the grooved portion 22, may be joined to a portion of the negative electrode 12 that is located at a radial distance of L / 3 or more and 2L / 3 or less from the innermost circumference.

[0041] According to this modified example, the current path of the negative electrode 12 to the negative electrode lead 121 is shortened, thereby reducing electrical resistance. The lower side of the negative electrode lead may be joined to a portion of the negative electrode where the radial distance from the innermost circumference is less than L / 3, or to a portion of the negative electrode where the radial distance from the innermost circumference is longer than 2L / 3.

[0042] The case in which the upper ends of the negative electrode leads 21 and 121 are joined to the lower surface 22a of the grooved portion 22 of the outer can 16 has been described. However, the upper ends of the negative electrode leads only need to be joined to a portion of the outer can's side surface that is above the upper insulating plate, and may, for example, be fixed to the inner circumferential surface of the grooved portion. Also, although the case in which the first electrode is the negative electrode 12 has been described, the first electrode may also be the positive electrode 11.

[0043] 10,110 Battery, 11 Positive electrode, 12 Negative electrode, 13 Separator, 14 Electrode body, 16 Outer casing, 17 Sealing body, 18 Upper insulating plate, 18a Through hole, 19 Lower insulating plate, 20 Positive electrode lead, 20a Positive electrode extension, 21,121 Negative electrode lead, 21a Negative electrode extension, 22 Grooved portion, 22a Lower surface of grooved portion, 23 Terminal plate, 24 Lower valve body, 25 Insulating plate, 26 Upper valve body, 27 Terminal cap, 27a Protrusion, 27b Ventilation hole, 28 Gasket, 29 Shoulder portion, 31 Bottom portion, 33 Peripheral portion, 39 Cylindrical portion, 121a Upper end of negative electrode lead.

Claims

1. A cylindrical battery comprising: an electrode body in which a first electrode and a second electrode are wound with a separator between them; an outer can for housing the electrode body; a sealing body that closes the opening of the outer can with a gasket; an insulating plate disposed on the end face of the electrode body on the side of the sealing body; and an electrode lead that is joined to the first electrode and includes an extension extending from the end face, wherein the extension is joined to the side of the outer can at a position closer to the opening than to the position facing the insulating plate.

2. The cylindrical battery according to claim 1, wherein the outer casing has a shoulder portion that is bent radially inward over its entire circumference and a grooved portion that is recessed radially inward over its entire circumference, the sealing body is sandwiched between the shoulder portion and the grooved portion via a gasket, and the extension portion is joined to the axial end face of the grooved portion on the electrode body side.

3. The cylindrical battery according to claim 1 or 2, wherein the first electrode is a negative electrode, and the electrode lead is joined to the outermost circumference of the negative electrode.

4. The cylindrical battery according to claim 1 or 2, wherein the first electrode is a negative electrode, and when the radial length from the innermost to the outermost circumference of the negative electrode is L, the electrode lead is joined to a portion of the negative electrode located at a radial distance of L / 3 or more and 2L / 3 or less from the innermost circumference.

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