Secondary battery and method for manufacturing secondary battery
By employing a double-layer gasket structure and heat treatment in the secondary battery, the problems of warping and wrinkling during gasket riveting are solved, ensuring the battery's airtightness and insulation, and improving the overall performance of the battery.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD
- Filing Date
- 2024-09-26
- Publication Date
- 2026-05-19
AI Technical Summary
In secondary batteries, the gaskets in the existing technology are prone to warping and wrinkling during riveting, which leads to a decrease in airtightness and makes it difficult to ensure the insulation of the battery interior.
The system employs a double-layer structure consisting of a first washer and a second washer. The first and second washers are adjacent to each other in the radial direction and are clamped into the sealing body from both sides in the axial direction before riveting. The washers are softened by heating to form a wavy boundary, ensuring a tight seal.
It effectively suppresses gasket warping and wrinkles, ensuring the internal sealing and insulation of the secondary battery, preventing foreign object intrusion, and improving battery performance.
Smart Images
Figure CN122070633A_ABST
Abstract
Description
Technical Field
[0001] This disclosure relates to secondary batteries and methods for manufacturing secondary batteries. Background Technology
[0002] Generally, in secondary batteries, the sealing body that blocks the opening of the outer can is riveted to the opening of the outer can by means of a resin gasket (for example, see Patent Document 1). By providing the gasket, the airtightness of the battery interior and the insulation between the outer can and the sealing body can be ensured.
[0003] Existing technical documents
[0004] Patent documents
[0005] Patent Document 1: International Publication No. 2016 / 157749 Summary of the Invention
[0006] As with the secondary battery disclosed in Patent Document 1, if the gasket is constructed from a single component, warping and wrinkling may sometimes occur near the radially inner end of the gasket when it is riveted to the opening of the outer can. If warping and wrinkling occur in the gasket, it may interfere with other components, which is not preferable.
[0007] Furthermore, it is known that if the gasket is made of a single component, the internal seal of the battery may sometimes decrease when the opening of the outer can is riveted. This is presumably because when the opening of the outer can is riveted, the resin material constituting the gasket is extruded radially inward, reducing the thickness of the gasket on the radially outer side.
[0008] Therefore, the purpose of this disclosure is to ensure the airtightness of the battery interior while suppressing the warping and wrinkling of the gaskets when riveting the opening of the outer can.
[0009] A secondary battery according to one embodiment of the present disclosure comprises: an electrode body formed by winding a positive electrode and a negative electrode with a separator between them; a cylindrical outer can having a bottom and housing the electrode body; a sealing body sealing the opening of the outer can; and an annular gasket between the outer can and the sealing body, wherein the sealing body is riveted to the opening of the outer can by the gasket, characterized in that the gasket includes a first gasket and a second gasket disposed on a bottom side of the first gasket, the sealing body being clamped into the outer can from both axial sides by the first gasket and the second gasket, and at least a portion of the first gasket being adjacent to the second gasket in the radial direction of the outer can.
[0010] Furthermore, one aspect of the present disclosure discloses a method for manufacturing a secondary battery comprising a cylindrical outer can having a bottom and housing an electrode body, a circular sealing body sealing the opening of the outer can, and an annular gasket between the outer can and the sealing body. The gasket is characterized by comprising a first gasket and a second gasket abutting against the first gasket and disposed on a lower side than the first gasket. The manufacturing method includes: a step of clamping the sealing body from both axial sides by the first gasket and the second gasket in a radially abutting position with at least a portion of the first gasket adjacent to the second gasket before riveting the opening of the outer can; and a step of bending the opening of the outer can radially inward and riveting the sealing body to the opening of the outer can via the gasket.
[0011] Another aspect of this disclosure discloses a method for manufacturing a secondary battery comprising a cylindrical outer can having a bottom and housing electrodes, a circular sealing body sealing the opening of the outer can, and an annular gasket made of resin material between the outer can and the sealing body. The gasket is characterized by comprising a first gasket and a second gasket abutting against the first gasket and disposed on a lower side than the first gasket. The manufacturing method includes: a step of clamping the sealing body into place from both axial sides by the first gasket and the second gasket before riveting the opening of the outer can; a step of heating the first gasket and the second gasket from the radial outside at a temperature higher than the softening temperature of the resin material; and a step of bending the opening of the outer can radially inward and riveting the sealing body to the opening of the outer can via the gasket.
[0012] According to one embodiment of the present disclosure, a secondary battery can ensure the airtightness of the battery interior while suppressing the warping and wrinkling of the gasket when riveting the opening of the outer can. Attached Figure Description
[0013] Figure 1 This is a cross-sectional view of a secondary battery as an example of an implementation method.
[0014] Figure 2 This is a cross-sectional view of the secondary battery in one embodiment before the outer can is riveted to the gasket.
[0015] Figure 3 This is a cross-sectional view of the state after the outer can of the secondary battery is riveted into the gasket of one embodiment.
[0016] Figure 4 This is a cross-sectional view of the secondary battery gasket in another example of the embodiment, before the outer can is riveted.
[0017] Figure 5This is a cross-sectional view of the secondary battery gasket in another example of the embodiment, before the outer can is riveted.
[0018] Figure 6 This is a cross-sectional view of the secondary battery gasket in another example of the embodiment, before the outer can is riveted. Detailed Implementation
[0019] Hereinafter, an example of an embodiment of the secondary battery of this disclosure will be described in detail with reference to the accompanying drawings. The embodiments described below are always examples, and this disclosure is not limited to these embodiments. Furthermore, this disclosure includes arrangements in which the constituent elements of the embodiments described below are selectively combined.
[0020] Figure 1 This is a schematic cross-sectional view of a secondary battery 10, illustrating one example of an embodiment. (See diagram below.) Figure 1 As shown, the secondary battery 10 includes an electrode body 14, an electrolyte (not shown), and an outer container 20 for housing the electrode body 14 and the electrolyte. The electrode body 14 has a positive electrode 11, a negative electrode 12, and a separator 13, and has a structure in which the positive electrode 11 and the negative electrode 12 are wound in a spiral shape with the separator 13 in between. The outer container 20 is a bottomed cylindrical metal container with an opening on one axial side, and the opening of the outer container 20 is sealed by a sealing body 30. Hereinafter, the sealing body 30 side of the secondary battery 10 in the axial (height direction) direction will be referred to as "upper", and the bottom 21 side of the outer container 20 in the axial direction will be referred to as "lower".
[0021] Electrolytes have lithium-ion conductivity. Electrolytes can be liquid electrolytes (electrolytes) or solid electrolytes.
[0022] The liquid electrolyte (electrolyte) comprises 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. The non-aqueous solvent may also contain halogen substitutes (e.g., fluoroethylene carbonate) obtained by replacing at least a portion of the hydrogen atoms in these solvents with halogen atoms such as fluorine. Examples of electrolyte salts include lithium salts such as LiPF6.
[0023] As a solid electrolyte, for example, solid or gel-like polymer electrolytes, inorganic solid electrolytes, etc., can be used. As an inorganic solid electrolyte, known materials (e.g., oxide-based solid electrolytes, sulfide-based solid electrolytes, halogen-based solid electrolytes, etc.) can be used in all-solid-state lithium-ion secondary batteries. Polymer electrolytes, for example, comprise lithium salts and matrix polymers, or non-aqueous solvents, lithium salts, and matrix polymers. As a matrix polymer, for example, polymer materials that absorb non-aqueous solvents and gel. Examples of polymer materials include fluoropolymers, acrylic resins, polyether resins, etc.
[0024] The positive electrode 11, negative electrode 12, and separator 13 constituting the electrode body 14 are all elongated strips, which are alternately stacked in the radial direction of the electrode body 14 by being wound in a spiral shape. The negative electrode 12 is formed to be one size larger than the positive electrode 11 to prevent lithium deposition. That is, the negative electrode 12 is formed to be longer than the positive electrode 11 in both the longitudinal and width (short) directions. The separator 13 is formed to be at least one size larger than the positive electrode 11, and two separators are arranged to sandwich the positive electrode 11. The secondary battery 10 includes insulating plates 16 and 17 respectively disposed above and below the electrode body 14.
[0025] The positive electrode 11 has a positive electrode core and a positive electrode flux layer formed on the positive electrode core. The positive electrode core can be a foil of a metal 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 disposed on the surface. Preferably, the positive electrode flux layer contains a positive electrode active material, a conductive agent, and a binder, and is formed on both sides of the positive electrode core except for the exposed portion (not shown) of the positive electrode core for soldering the positive electrode lead 18. The positive electrode 11 can be manufactured, for example, by coating the positive electrode core with a positive electrode flux slurry containing a positive electrode active material, a conductive agent, and a binder, and then compressing the slurry after drying to form the positive electrode flux layer on both sides of the positive electrode core.
[0026] The positive electrode composite layer comprises particulate lithium metal composite oxides as the positive electrode active material. The lithium metal composite oxide is a composite oxide containing metal elements such as Co, Mn, Ni, and Al in addition to Li. The metal elements constituting the lithium metal composite oxide are, for example, selected from at least one of Mg, Al, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Y, Zr, Sn, Sb, W, Pb, and Bi. Preferably, it contains at least one of Co, Ni, and Mn. Examples of suitable composite oxides include lithium metal composite oxides containing Ni, Co, and Mn, and lithium metal composite oxides containing Ni, Co, and Al.
[0027] Examples of conductive agents included in the positive electrode binder layer include carbon black such as acetylene black and Ketjen black, graphite, carbon nanotubes (CNTs), carbon nanofibers, and graphene. Examples of binders included in the positive electrode binder layer include fluorinated resins such as polytetrafluoroethylene (PTFE) and poly(1,1-difluoroethylene) (PVDF), polyacrylonitrile (PAN), polyimide, acrylic resin, and polyolefins. Furthermore, these resins, carboxymethyl cellulose (CMC) or its salts, and polyethylene oxide (PEO) can be used in combination.
[0028] The negative electrode 12 has a negative electrode core and a negative electrode binder layer formed on the negative electrode core. The negative electrode core can be a foil of a metal 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 disposed on the surface. The negative electrode binder layer contains a negative electrode active material, a binder, and a conductive agent included as needed, and is preferably formed on both sides of the negative electrode core except for the exposed portion (not shown) of the negative electrode core for soldering the negative electrode lead 19. The negative electrode 12 can be manufactured by coating the surface of the negative electrode core with a negative electrode binder slurry containing a negative electrode active material and a binder, and then compressing the slurry after the coating has dried to form the negative electrode binder layer on both sides of the negative electrode core.
[0029] The negative electrode composite layer typically comprises a carbon material that reversibly absorbs and releases lithium ions as the negative electrode active material. Suitable examples of carbon materials include natural graphite such as flake graphite, block graphite, and amorphous graphite, as well as artificial graphite such as block graphite (MAG) and graphitized mesophase carbon microspheres (MCMB). Alternatively, materials containing at least one of elements alloyed with Li, such as Si and Sn, or materials containing these elements can also be used as the negative electrode active material. Among these, composite materials containing Si are preferred.
[0030] Suitable examples of Si-containing composite materials include materials in which Si microparticles are dispersed in a SiO2 phase or a silicate phase such as lithium silicate, or materials in which Si microparticles are dispersed in an amorphous carbon phase. A conductive layer, such as a carbon film, is formed on the particle surface of this composite material. From the viewpoint of balancing high capacity and high durability of the battery, it is preferable to use a composite material containing carbon materials and Si as the negative electrode active material.
[0031] Similar to the case of the positive electrode binder layer, the binder included in the negative electrode binder layer can also be fluorinated resins, PAN, polyimide, acrylic resin, polyolefins, etc., but styrene-butadiene rubber (SBR) is preferred. Furthermore, the negative electrode binder layer preferably includes CMC or its salts, polyacrylic acid (PAA) or its salts, polyvinyl alcohol (PVA), etc. Among these, using SBR and CMC or its salts, PAA or its salts, etc., is suitable. The negative electrode binder layer may also include conductive agents such as CNTs.
[0032] The separator 13 can be a porous sheet with ion permeability and insulation. Specific examples of porous sheets include microporous films, woven fabrics, and nonwoven fabrics. Suitable materials for the separator 13 include polyolefins such as polyethylene and polypropylene, and cellulose. The separator 13 can be a single-layer structure or a multi-layer structure. Furthermore, a resin layer with high heat resistance, such as an aromatic polyamide resin, can be formed on the surface of the separator 13. At the interface between at least one of the positive electrode 11 and the negative electrode 12 and the separator 13, a filler layer containing inorganic fillers can also be formed.
[0033] A positive lead 18 is connected to the positive terminal 11, and a negative lead 19 is connected to the winding end side of the negative terminal 12. The positive lead 18 extends towards the sealing body 30 through the through hole in the insulating plate 16, and the negative lead 19 extends towards the bottom 21 of the outer packaging can 20 through the outer side of the insulating plate 17. The positive lead 18 is connected to the lower surface of the internal terminal plate 31 of the sealing body 30 by welding or the like, making the sealing body 30 the positive terminal. The negative lead 19 is connected to the inner surface of the bottom 21 of the metal outer packaging can 20 by welding or the like, making the outer packaging can 20 the negative terminal.
[0034] The outer can 20 is a bottomed cylindrical metal container with an opening on one axial side. The outer can 20 has a bottom 21 and a side portion 22 that forms the side of the secondary battery 10. The side portion 22 is the part of the outer can 20 other than the bottom 21, and includes the groove portion 23 and the opening portion 24 described later.
[0035] The groove 23 is a portion of the side portion 22 that extends radially inward, and its upper surface supports the sealing body 30. The groove 23 is formed in a ring shape along the circumference of the outer can 20. The groove 23 can be formed, for example, by spinning a portion of the side portion 22 radially inward to make it annularly recessed in the radially inward direction.
[0036] The opening 24 is the area above the groove 23 in the side portion 22, forming the opening of the outer can 20. When the sealing body 30 is riveted and fixed to the outer can 20, the opening 24 is bent radially inward toward the periphery of the sealing body 30. Thus, the opening 24 forms an opening side portion 25 that forms a portion of the side of the secondary battery 10 and covers the outer peripheral surface of the gasket 40, and an opening upper surface portion 26 that forms a portion of the upper surface of the secondary battery 10 and covers a portion of the upper surface of the gasket 40. In this embodiment, the radially inner end of the opening upper surface portion 26 is located radially outer than the radially inner end of the gasket 40. That is, the upper surface of the radially inner end of the gasket 40 is not covered by the opening upper surface portion 26.
[0037] The sealing body 30 is a circular plate-shaped component equipped with a safety valve. The sealing body 30 has a structure in which an inner terminal plate 31, an insulating member 32, and an outer terminal plate 33 are stacked sequentially from the electrode body 14 side.
[0038] The internal terminal block 31 is a metal plate comprising a thick-walled portion 31A for connecting the positive electrode lead 18, and a thin-walled central portion 31B that is cut off from the thick-walled portion 31A when the internal pressure of the battery exceeds a predetermined threshold. A plurality of vent holes 31C are formed in the thick-walled portion 31A.
[0039] The insulating member 32 insulates the portion of the inner terminal plate 31 from the connection portion of the outer terminal plate 33. An opening 32A is formed in the radial center of the insulating member 32, and a vent 32B is formed in the portion of the insulating member 32 that overlaps with the vent 31C of the inner terminal plate 31.
[0040] The outer terminal plate 33 forms part of the upper surface of the secondary battery 10 and is disposed opposite to the inner terminal plate 31 via the insulating member 32. The outer terminal plate 33 has a thin-walled portion 33A that breaks when the internal pressure of the secondary battery 10 exceeds a predetermined threshold. The outer terminal plate 33 is connected to the central portion 31B of the inner terminal plate 31 at its radial center by welding or the like. In addition, details will be described later, but the radially outer side of the outer terminal plate 33 is held between the opening 24 formed by bending the opening of the outer can 20 inward and the groove 23 via a gasket 40.
[0041] If an abnormality occurs in the secondary battery 10 and the internal pressure rises, the generated high-temperature gas causes the internal terminal plate 31 to be pressed upwards, breaking the internal terminal plate 31 and severing the central portion 31B from the thick-walled portion 31A. The external terminal plate 33 deforms in a manner that protrudes outwards from the battery. As a result, the current path in the sealing body 30 is blocked. Furthermore, after the current path is blocked, if the internal pressure of the secondary battery 10 rises further, the thin-walled portion 33A of the external terminal plate 33 breaks, forming a gas outlet in the external terminal plate 33.
[0042] Furthermore, the structure of the sealing body 30 is not limited to Figure 1 The structure shown. The sealing body 30 may also have, for example, a convex cap that covers the outer terminal plate 33.
[0043] Gasket 40 is a sealing material located between the outer can 20 and the external terminal plate 33 that constitutes the sealing body 30. By providing gasket 40, the gap between the outer can 20 and the external terminal plate 33 is sealed, ensuring the airtightness of the interior of the secondary battery 10. In other words, gasket 40 is required to seal the gap between the outer can 20 and the external terminal plate 33.
[0044] Next, further reference Figure 2as well as Figure 3 The details of washer 40 are explained below. Figure 2 This is a cross-sectional view of the gasket 40 before it is riveted to the outer can 20. Figure 3 This is a cross-sectional view of the gasket 40 after it has been riveted to the outer can 20. Furthermore, in Figure 2 as well as Figure 3 For ease of explanation, a gap is provided at the boundary between the first washer 41 and the second washer 42 in the illustration.
[0045] like Figure 2 as well as Figure 3 As shown, the gasket 40 includes a first gasket 41 and a second gasket 42 disposed on the side of the first gasket 41 closer to the bottom 21. The thicknesses of the first gasket 41 and the second gasket 42 may differ from each other, but from the viewpoint of ensuring the airtightness of the interior of the secondary battery 10, it is preferable that they are substantially the same. Hereinafter, the first gasket 41 and the second gasket 42 are sometimes referred to together as gasket 40.
[0046] Both the first washer 41 and the second washer 42 are annular in shape, both before and after riveting the outer can 20. In axial cross-section, they have a roughly L-shaped form. Furthermore, both the first washer 41 and the second washer 42 are configured to clamp the outer terminal plate 33 from both axial sides, both before and after riveting. More specifically, the first washer 41 covers the radially outer side of the upper surface 33B and the upper side of the outer peripheral surface 33D of the outer terminal plate 33, both before and after riveting. Similarly, the second washer 42 covers the radially outer side of the lower surface 33C and the lower side of the outer peripheral surface 33D of the outer terminal plate 33, both before and after riveting. Details will be described later, but even before riveting the outer can 20, by arranging the first washer 41 and the second washer 42 in such a way that the outer terminal plate 33 is clamped from both sides in the axial direction, the deformation of the first washer 41 and the second washer 42 during the riveting of the outer can 20 can be reduced.
[0047] Both the first gasket 41 and the second gasket 42 are made of resin material. Examples of resin materials used to construct the first gasket 41 and the second gasket 42 include polyolefin resins such as polypropylene (PP), fluorinated resins such as tetrafluoroethylene-perfluoroalkoxyethylene copolymer (PFA), and polyphenylene sulfide (PPS). By using resin material for the first gasket 41 and the second gasket 42, it is easy to ensure the insulation between the outer can 20 and the sealing body 30 while sealing the gap between them. Furthermore, the first gasket 41 and the second gasket 42 can be made of different resin materials, but from a productivity point of view, it is preferable that they are made of the same resin material.
[0048] At least a portion of the first washer 41 is radially adjacent to the second washer 42. In this embodiment, a protrusion 44 is provided on the radially inner side of the second washer 42, and a recess 43 for fitting the protrusion 44 is provided on the radially inner side of the first washer 41. Thus, a region is formed in the radial direction where the first washer 41 and the second washer 42 are adjacent.
[0049] When the opening 24 of the outer can 20 is riveted, the first gasket 41 is pressed radially inward. At this time, by providing a region where the first gasket 41 and the second gasket 42 are radially adjacent, the first gasket 41 can be prevented from detaching from the second gasket 42. As a result, the internal airtightness of the secondary battery 10 can be ensured. In other words, if there is no radially adjacent region between the first gasket 41 and the second gasket 42, when the opening 24 of the outer can 20 is riveted, the first gasket 41 may detach from the second gasket 42, and the internal airtightness of the secondary battery 10 may decrease.
[0050] Furthermore, by providing a region where the first gasket 41 and the second gasket 42 are radially adjacent, a step is formed at the boundary line between the first gasket 41 and the second gasket 42. This extends the distance between the boundary lines of the first gasket 41 and the second gasket 42. As a result, for example, even if foreign matter such as electrolyte is present on the inner surface of the opening 24, its intrusion into the sealing body 30 can be suppressed. In other words, without a region where the first gasket 41 and the second gasket 42 are radially adjacent, and without a step forming at the boundary line between the first gasket 41 and the second gasket 42, foreign matter present on the inner surface of the opening 24 may sometimes intrude into the sealing body 30. Assuming that this foreign matter is conductive, the insulation between the outer can 20 and the sealing body 30 cannot be adequately ensured, and battery performance may sometimes degrade.
[0051] The depth of the recess 43 is the same as the height of the protrusion 44. As a result, it is difficult to form a gap between the first washer 41 and the second washer 42, thus ensuring the airtightness of the interior of the secondary battery 10.
[0052] The depth of the recess 43 (the height of the protrusion 44) is preferably 20% or more, more preferably 25% or more, of the thickness of the sealing body 30 (in this embodiment, the outer terminal plate 33) held by the first washer 41 and the second washer 42. By setting the depth of the recess 43 (the height of the protrusion 44) to be 20% or more of the thickness of the sealing body 30 held by the first washer 41 and the second washer 42, the first washer 41 is less likely to detach from the second washer 42 during riveting. In addition, by setting the depth of the recess 43 (the height of the protrusion 44) to be 20% or more of the thickness of the sealing body 30 held by the first washer 41 and the second washer 42, a step of appropriate size can be formed at the boundary line between the first washer 41 and the second washer 42. Furthermore, the upper limit of the depth of the recess 43 (the height of the protrusion 44) is, for example, 90% of the thickness of the sealing body 30 held by the first washer 41 and the second washer 42.
[0053] The recess 43 and the protrusion 44 are preferably provided around the entire circumference of the first washer 41 and the second washer 42. In this case, the first washer 41 is less likely to detach from the second washer 42 during riveting.
[0054] Furthermore, in this embodiment, a recess 43 is provided in the first washer 41 and a protrusion 44 is provided in the second washer 42, but this is not a limitation; a protrusion may be provided in the first washer 41 and a recess in the second washer 42. Additionally, the location of the protrusion 44 is not limited to the radially inner side of the second washer 42; it may be provided in the radially central portion of the second washer 42 or the radially outer side of the second washer 42.
[0055] Here, the configuration of a conventional gasket consisting of a single component will be described, and the effects of the gasket 40 consisting of two components in this embodiment will be explained. Generally, when a gasket consists of a single component, a gasket with an approximately L-shaped cross-section in the axial direction is used before riveting the outer can 20. Before riveting the outer can 20, this gasket is configured to abut against the lower surface 33C and the outer peripheral surface 33D of the outer terminal plate 33, but not against the upper surface 33B of the outer terminal plate 33, with the upper region of the gasket abutting against the opening 24. That is, when a gasket consists of a single component, it is configured so that the outer terminal plate 33 is not clamped from both sides in the axial direction before riveting the outer can 20. Furthermore, when riveting the outer can 20, the upper region of the gasket is pressed against the opening 24 and bent radially inward toward the periphery of the outer terminal plate 33. Thus, the washer is positioned to clamp the external terminal block 33 from both axial sides.
[0056] Here, when the upper region of the gasket is bent radially inward, the volume near the bent area sometimes decreases. Consequently, the volume at the radially inner end of the gasket increases, resulting in warping or wrinkling near the radially inner end. Furthermore, when the upper region of the gasket is bent radially inward, the outer periphery of the gasket is sometimes stretched towards the radially inner end. This reduces the volume of the outer periphery, sometimes decreasing the internal sealing of the secondary battery 10.
[0057] On the other hand, by using two components, namely a first washer 41 and a second washer 42, as in this embodiment, the gasket 40 can clamp the external terminal plate 33 from both axial sides even before riveting the outer can 20. Therefore, the gasket 40 is not bent radially inward during riveting of the outer can 20, thus minimizing volume change. As a result, the internal sealing of the secondary battery 10 is ensured while suppressing warping and wrinkling of the gasket 40.
[0058] Next, refer to Figures 1-3 The manufacturing process of the secondary battery 10 according to this embodiment will be described.
[0059] The manufacturing process of the secondary battery 10 includes, for example, an installation process of installing a gasket 40 on the sealing body 30; an insertion process of inserting the electrode body 14 into the outer can 20 and connecting the sealing body 30 to the electrode body 14; and a riveting process of riveting and fixing the opening 24 of the outer can 20. Furthermore, the order of the installation and insertion processes is not particularly limited, and the installation process may be performed after the insertion process.
[0060] During the installation process, a first washer 41 and a second washer 42 are installed radially outward of the sealing body 30 (in this embodiment, the outer terminal plate 33). More specifically, firstly, the second washer 42 is positioned from the lower part of the outer terminal plate 33 such that it covers the radially outer side of the lower surface 33C and the lower side of the outer peripheral surface 33D of the outer terminal plate 33. Then, the first washer 41 is positioned from the upper part of the outer terminal plate 33 such that it covers the radially outer side of the upper surface 33B and the upper side of the outer peripheral surface 33D of the outer terminal plate 33. At this time, the first washer 41 is positioned such that the protrusion 44 provided on the second washer 42 engages with the recess 43 provided on the first washer 41. Therefore, with the first washer 41 and the second washer 42 adjacent to each other in the radial direction, the external terminal plate 33 can be clamped from both sides in the axial direction using the first washer 41 and the second washer 42.
[0061] In the insertion process, the sealing body 30, which was produced in the installation process, is connected to the electrode body 14 via the positive lead 18. The electrode body 14 is then inserted into the outer can 20. Furthermore, a groove 23 supporting the sealing body 30 is formed on the opening side of the side portion 22 of the outer can 20 by spinning from the radially outward direction.
[0062] In the riveting process, such as Figure 2 As shown, the sealing body 30 is inserted into the outer can 20, and the external terminal plate 33 is positioned on the upper surface of the groove 23. Furthermore, as... Figure 3 As shown, the opening 24 is bent radially inward toward the periphery of the outer terminal plate 33. Thus, the sealing body 30 is riveted and fixed to the opening 24 of the outer can 20 via a gasket 40.
[0063] Next, refer to Figures 4-6 This shows a variation of the shape of washer 40. Figures 4-6 This is a cross-sectional view of the gasket 40 before it is riveted to the outer can 20. Furthermore, in Figures 4-6 For ease of explanation, a gap is provided at the boundary between the first washer 41 and the second washer 42 in the illustration.
[0064] like Figure 4 As shown, a claw 46 can be provided on the outer peripheral surface of the protrusion 44 of the second washer 42, and a groove 45 that engages with the claw 46 can be provided on the inner peripheral surface of the recess 43 of the first washer 41. By providing the claw 46 and the groove 45, the first washer 41 and the second washer 42 can be firmly fixed. As a result, when riveting the outer can 20, the first washer 41 can be more prevented from deviating from the second washer 42, and the internal sealing of the secondary battery 10 can be better ensured. In addition, the claw 46 and the groove 45 can be provided all around the circumference of the first washer 41 and the second washer 42, or they can be provided only in a portion of the circumferential area.
[0065] In addition, such as Figure 5 As shown, an external threaded portion 48 can be provided on the outer peripheral surface of the protrusion 44 of the second washer 42, and an internal threaded portion 47 that engages with the external threaded portion 48 can be provided on the inner peripheral surface of the recess 43 of the first washer 41. By providing the external threaded portion 48 and the internal threaded portion 47, the first washer 41 and the second washer 42 can be firmly fixed. As a result, when riveting the outer can 20, the first washer 41 can be more firmly prevented from detaching from the second washer 42, and the internal airtightness of the secondary battery 10 can be better ensured.
[0066] In addition, such as Figure 6As shown, in an axial cross-sectional view, the boundary line between the first gasket 41 and the second gasket 42 can also be wavy. By setting the boundary line between the first gasket 41 and the second gasket 42 to be wavy, it is possible to define the area where the first gasket 41 and the second gasket 42 are adjacent in the radial direction. As a result, when the outer can 20 is riveted, the first gasket 41 can be prevented from detaching from the second gasket 42, thus ensuring the internal airtightness of the secondary battery 10.
[0067] Here, as a method for setting the boundary line of the first gasket 41 and the second gasket 42 as a wave, one example is heating the first gasket 41 and the second gasket 42 from the radially outer side at a temperature higher than the softening temperature of the resin material. More specifically, firstly, before riveting the opening of the outer can 20, the sealing body 30 (in this embodiment, the outer terminal plate 33) is clamped in from both axial sides by the first gasket 41 and the second gasket 42. At this time, the boundary line of the first gasket 41 and the second gasket 42 can be a straight line, or the boundary line of the first gasket 41 and the second gasket 42 can be without a step. That is, the first gasket 41 and the second gasket 42 can be without a recess 43 and a protrusion 44, and the surfaces of the first gasket 41 and the second gasket 42 that abut are flat.
[0068] Furthermore, with the outer terminal plate 33 clamped in from both axial sides by the first washer 41 and the second washer 42, the first washer 41 and the second washer 42 are heated from the radial outside at a temperature above the softening temperature of the resin material (for example, above 150°C). As a result, the resin material constituting the first washer 41 and the second washer 42 softens, and the boundary lines of the first washer 41 and the second washer 42 become wavy. Moreover, the boundary lines of the first washer 41 and the second washer 42 after heat treatment are not limited to wavy lines; they can also be straight lines or have an uneven shape.
[0069] This disclosure is further described through the following embodiments.
[0070] Configuration 1: A secondary battery comprising: an electrode body formed by winding a positive electrode and a negative electrode with a separator between them; a cylindrical outer can having a bottom and housing the electrode body; a circular sealing body sealing the opening of the outer can; and an annular gasket between the outer can and the sealing body, the sealing body being riveted to the opening of the outer can by the gasket, the gasket including a first gasket and a second gasket disposed on a side closer to the bottom than the first gasket, the sealing body being clamped into the outer can from both axial sides by the first gasket and the second gasket, at least a portion of the first gasket being adjacent to the second gasket in the radial direction of the outer can.
[0071] Configuration 2: In the secondary battery according to technical solution 1, one of the first gasket and the second gasket has a protrusion, and the other of the first gasket and the second gasket has a recess for the protrusion to be disposed.
[0072] Configuration 3: In the secondary battery according to technical solution 2, the protrusion and the recess are provided throughout the entire circumference of the gasket.
[0073] Configuration 4: The secondary battery according to technical solution 2 or 3 has a claw portion provided in the protrusion and a groove portion provided in the recess to engage with the claw portion.
[0074] Configuration 5: According to the secondary battery of technical solution 2, an external threaded portion is provided in the protrusion, and an internal threaded portion that engages with the external threaded portion is provided in the concave portion.
[0075] Configuration 6: In the secondary battery according to technical solution 1, when viewed in axial section of the outer can, the boundary line between the first gasket and the second gasket is wavy.
[0076] Configuration 7: A method for manufacturing a secondary battery, the secondary battery comprising: a cylindrical outer can having a bottom and housing an electrode body; a circular sealing body sealing the opening of the outer can; and an annular gasket between the outer can and the sealing body, the gasket including a first gasket and a second gasket abutting against the first gasket and disposed on a side closer to the bottom than the first gasket, the manufacturing method comprising: a step of clamping the sealing body from both axial sides by the first gasket and the second gasket with at least a portion of the first gasket abutting the second gasket in the radial direction before riveting the opening of the outer can; and a step of bending the opening of the outer can radially inward and riveting the sealing body to the opening of the outer can via the gasket.
[0077] Configuration 8: A method for manufacturing a secondary battery, the secondary battery comprising: a cylindrical outer can having a bottom and housing an electrode body; a circular sealing body sealing the opening of the outer can; and an annular gasket made of resin material between the outer can and the sealing body, the gasket including a first gasket and a second gasket disposed with respect to the first gasket at a position closer to the bottom than the first gasket, the manufacturing method comprising: a step of clamping the sealing body from both axial sides by the first gasket and the second gasket before riveting the opening of the outer can; a step of heating the first gasket and the second gasket from the radial outside at a temperature higher than the softening temperature of the resin material; and a step of bending the opening of the outer can radially inward and riveting the sealing body to the opening of the outer can via the gasket.
[0078] Explanation of reference numerals in the attached figures
[0079] 10 Secondary battery, 11 Positive electrode, 12 Negative electrode, 13 Separator, 14 Electrode body, 16, 17 Insulating plate, 18 Positive electrode lead, 19 Negative electrode lead, 20 Outer can, 21 Bottom, 22 Side part, 23 Groove, 24 Opening, 25 Opening side part, 26 Opening upper surface part, 30 Sealing body, 31 Internal terminal plate, 31A Thick wall part, 31B Central part, 31C Vent hole, 32 Insulating component, 32A Opening, 32B Vent hole, 33 External terminal plate, 33A Thin wall part, 33B Upper surface, 33C Lower surface, 33D Outer peripheral surface, 40 Washer, 41 First washer, 42 Second washer, 43 Recess, 44 Protrusion, 45 Groove, 46 Claw, 47 Internal thread section, 48 external thread section.
Claims
1. A secondary battery, comprising: An electrode body obtained by winding the positive and negative electrodes together with a separator in between; A cylindrical outer can having a bottom and housing the electrode body; A circular, plate-shaped sealing body that blocks the opening of the outer can; and An annular gasket located between the outer can and the sealing body. The sealing body is riveted and fixed to the opening of the outer can by means of the gasket. in, The washer includes a first washer and a second washer disposed on the bottom side of the first washer. The sealing body is clamped in from both axial sides of the outer can by the first gasket and the second gasket. At least a portion of the first gasket is adjacent to the second gasket in the radial direction of the outer can.
2. The secondary battery according to claim 1, wherein, One of the first washer and the second washer has a protrusion. The first washer and the second washer each have a recess for the protrusion to be disposed.
3. The secondary battery according to claim 2, wherein, The protrusions and recesses are provided throughout the entire circumference of the washer.
4. The secondary battery according to claim 2, wherein, A claw portion is provided on the protrusion. The recess is provided with a groove that engages with the claw portion.
5. The secondary battery according to claim 2, wherein, The protrusion is provided with an external thread. An internal thread portion that engages with the external thread portion is provided in the recess.
6. The secondary battery according to claim 1, wherein, In an axial cross-sectional view of the outer can, the boundary line between the first gasket and the second gasket is wavy.
7. A method for manufacturing a secondary battery, The secondary battery has the following features: A cylindrical outer can having a bottom and housing the electrode body; A circular, plate-shaped sealing body that blocks the opening of the outer can; and An annular gasket located between the outer can and the sealing body. in, The washer includes a first washer and a second washer that abuts against the first washer and is disposed on a side closer to the bottom than the first washer. The manufacturing method includes: Before riveting the opening of the outer can, the sealing body is clamped in from both axial sides by the first and second washers with at least a portion of the first washer abutting the second washer in the radial direction of the outer can; and The process of bending the opening of the outer can radially inward and fixing the sealing body to the opening of the outer can by means of the gasket.
8. A method for manufacturing a secondary battery, The secondary battery has the following features: A cylindrical outer can having a bottom and housing the electrode body; A circular, plate-shaped sealing body that blocks the opening of the outer can; and An annular gasket made of resin material is located between the outer can and the sealing body. in, The washer includes a first washer and a second washer that abuts against the first washer and is disposed on a side closer to the bottom than the first washer. The manufacturing method includes: The process of clamping the sealing body from both axial sides by the first washer and the second washer before riveting the opening of the outer can; The process of heating the first gasket and the second gasket from the radial outer side at a temperature higher than the softening temperature of the resin material; and The process of bending the opening of the outer can radially inward and fixing the sealing body to the opening of the outer can by means of the gasket.