Cylindrical battery

Abstract

The purpose of this disclosure is to reduce the number of components of the sealing body in a cylindrical battery by providing a current-cutting function to the metal part constituting the sealing body that blocks one end of the outer can. The cylindrical battery (10) includes: a bottomed cylindrical outer can (100); a sealing body (11) that blocks one end of the outer can; an electrode body (20) disposed inside the outer can; and an insulating resin part (18) disposed between the outer can and the sealing body. The sealing body has a metal part (12) connected to a positive electrode lead (21a) extending from the electrode body. The metal part has a fracture-prone portion (16) further radially inward than the connection between the metal part and the positive electrode lead, and is riveted to the outer can via the resin part. The resin part is riveted to the metal part further radially inward than the fracture-prone portion.

Description

Technical Field

[0001] This disclosure relates to cylindrical batteries. Background Technology

[0002] In recent years, the applications of rechargeable batteries have expanded to include power sources for electric vehicles and energy storage devices for utilizing natural energy sources, with expectations for further increases in capacity. Electric vehicles and energy storage devices utilize battery modules formed by connecting multiple rechargeable batteries in series or parallel via external leads. With the increasing capacity of rechargeable batteries, there is a growing demand for higher safety standards for both the batteries and battery modules. Previously, in cases where abnormal pressure rises within the battery due to overcharging, thermal runaway and rupture of the rechargeable battery were prevented by cutting off the current path within the battery.

[0003] Patent Document 1 describes a cylindrical battery in which a current-cutting mechanism is assembled into a sealing body that seals one end of the outer can to ensure safety. This current-cutting mechanism is constructed by combining a metal valve body, an insulating member, and a metal body with vent holes. The valve body and the metal body are connected to each other at their center portions, and an insulating member is sandwiched between their outer peripheries. If the internal pressure of the battery rises, the valve body pulls the connection portion to the metal body outwards, causing the connection portion, or the thin-walled portion of the metal body, to break, thereby cutting off the current path between the valve body and the metal body. Furthermore, if the internal pressure of the battery rises again, the thin-walled portion of the valve body becomes the starting point, causing the valve body to break, thereby releasing the gas inside the battery.

[0004] Prior art literature

[0005] Patent documents

[0006] Patent Document 1: International Publication No. 2016 / 157748 Summary of the Invention

[0007] -The problem the invention aims to solve-

[0008] In the structure described in Patent Document 1, the sealing body, which blocks one end of the outer can, has a current-cutting function. The sealing body comprises three components: a valve body, an insulating member, and a metal body. These components are required to operate reliably in the event of a battery malfunction, necessitating complex and high-precision machining. Therefore, the increased number of components in the sealing body, as described in Patent Document 1, results in a significant increase in processing time. It is desirable to reduce the number of components in the sealing body.

[0009] The purpose of this disclosure is to provide a cylindrical battery that reduces the number of components of the sealing body by giving the metal part constituting the sealing body at one end of the plugging outer can a current cutting function.

[0010] -Methods used to solve problems-

[0011] The cylindrical battery disclosed herein comprises: a bottomed cylindrical outer can; a sealing body that blocks one end of the outer can; an electrode body disposed inside the outer can; and an insulating resin component disposed between the outer can and the sealing body. The sealing body has a metal component that is electrically connected to an electrode lead extending from the electrode body. The metal component has a fracture-prone portion further in the radial direction than the connection between the metal component and the electrode lead. The sealing body is riveted and fixed to the outer can via the resin component. The resin component is riveted and fixed to the metal component further in the radial direction than the fracture-prone portion.

[0012] -Invention Effects-

[0013] According to the cylindrical battery disclosed herein, since the metal components constituting the sealing body can have a current-cutting function, the number of components constituting the sealing body can be reduced. Attached Figure Description

[0014] Figure 1 This is a cross-sectional view of a cylindrical battery, representing one embodiment of the invention.

[0015] Figure 2 It means from Figure 1 The state in which the battery internal pressure rises, thereby causing the current cut-off mechanism to operate, is related to... Figure 1 The diagram corresponding to part A.

[0016] Figure 3 It means from Figure 2 The state in which the internal pressure of the battery further increases, thereby causing the gas discharge mechanism to operate, is related to the state in which the internal pressure of the battery further increases. Figure 1 The diagram corresponding to part A.

[0017] Figure 4 This is a cross-sectional view of a comparative example cylindrical battery. Detailed Implementation

[0018] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, specific shapes, materials, orientations, etc., are illustrative to facilitate understanding of this disclosure and can be appropriately varied depending on the application, purpose, and specifications of the cylindrical battery. The following description pertains to the case where the cylindrical battery is a non-aqueous electrolyte secondary battery, but the cylindrical battery is not limited to this.

[0019] Figure 1This is a cross-sectional view of the cylindrical battery 10 according to the embodiment. For example, the cylindrical battery 10 uses a non-aqueous electrolyte secondary battery such as a lithium-ion battery. The cylindrical battery 10 is configured to house the electrode body 20 and a non-aqueous electrolyte (not shown) inside a generally cylindrical, i.e., bottom-shaped outer can 100. At one end of the outer can 100 ( Figure 1 The opening at the upper end of the outer can 100 is sealed by the sealing body 11 via an insulating resin component 18. Thus, the opening at one end of the outer can 100 is blocked by the sealing body 11 via the resin component 18. The resin component 18 is an insulating member, serving as a gasket to seal between the outer can 100 and the sealing body 11, but also, as described later, venting gas when the internal pressure of the battery rises. The non-aqueous electrolyte includes a non-aqueous solvent and an electrolyte salt dissolved in a non-aqueous solvent. The non-aqueous electrolyte is not limited to a liquid electrolyte and may also be a solid electrolyte using a gel polymer, etc.

[0020] The electrode body 20 is a wound type, having a positive electrode plate 21, a negative electrode plate 22, and a separator 23. The positive electrode plate 21 and the negative electrode plate 22 are wound into a vortex shape with the separator 23 in between. Hereinafter, the side of the electrode body 20 in the direction of the winding axis is sometimes referred to as "upper" and the other side in the direction of the winding axis is referred to as "lower".

[0021] The sealing body 11 is composed solely of a metal component 12. The metal component 12 functions as both a positive terminal and a current-cutting mechanism that interrupts the current path when the internal pressure of the battery rises. The metal component 12 includes: a circular outer end plate portion 13 disposed at the outer end of the battery; a circular inner end plate portion 15 disposed at the inner side of the battery; and a circular connecting portion 17 connecting the outer end plate portion 13 and the inner end plate portion 15. The outer diameter of the outer end plate portion 13 is smaller than the outer diameter of the inner end plate portion 15. The outer diameter of the connecting portion 17 is smaller than the outer diameters of both the outer end plate portion 13 and the inner end plate portion 15. The outer end plate portion 13, the inner end plate portion 15, and the connecting portion 17 are coaxial, with their central axes aligned. Thus, in the metal component 12, a circular groove 12a is formed between the outer end plate portion 13 and the inner end plate portion 15, and a flange portion 15a is formed on the inner end plate portion 15 further radially outward than the connecting portion 17. Metal component 12 can be made of, for example, aluminum or an aluminum alloy. On the outer surface of the external terminal formed by the outer end plate portion 13 ( Figure 1 The upper surface of the battery module (not shown) is joined by welding to external leads (not shown) for electrical connection with other cylindrical batteries in the battery module (not shown).

[0022] In the inner end plate portion 15, the end of the positive electrode lead 21a extending from the electrode body 20 is connected to the inner surface of a radial portion of the flange portion 15a. The positive electrode lead 21a corresponds to the electrode lead. Furthermore, the flange portion 15a has a fracture-prone portion 16 further radially inward than the connection portion G between the metal part 12 and the positive electrode lead 21a. The fracture-prone portion 16 is an annular thin-walled portion formed in the radial portion of the flange portion 15a, which is fractured by the inner surface of the flange portion 15a ( Figure 1 A radial portion of the lower side surface of the flange portion 15a forms an annular groove 15b, thereby forming a fracture-prone portion 16. The fracture-prone portion 16 can also be formed on the outer side surface of the flange portion 15a. Figure 1 (The upper side).

[0023] Resin component 18 is disposed between the inner peripheral surface of the opening and the outer peripheral surface of the sealing body 11, the opening being formed at one end of the outer can 100. Figure 1 The upper end). The cross-sectional shape of a circumferential portion of the resin component 18 is the outer end of the battery ( Figure 1 The upper end of the battery is greater than the inner end of the battery. Figure 1 The lower end of the inner end plate 15 is roughly J-shaped and forms a ring when viewed from above. The flange 15a of the inner end plate 15 is riveted to the outer can 100 via the resin component 18. The resin component 18 is held between one end of the outer can 100 and the outer peripheral surface of the sealing body 11 in a compressed state, and is riveted to the inner side of the metal component 12 in the radial direction, further inside the easily breakable part 16. For example, as Figure 1 As shown, the front end of the resin component 18, which extends from between the flange 15a and one end of the outer can 100, is riveted to and fixed by the outer end plate 13 and the inner end plate 15. The front end of the resin component 18 is riveted to and fixed throughout its entire circumference by the metal component 12, thereby forming a sealing structure between the front end of the resin component 18 and the sealing body 11. Thus, even if the internal pressure of the battery increases and the easily breakable part 16 breaks, the internal airtightness of the battery is ensured. The resin component 18 can be made of a material that ensures insulation and does not affect the battery characteristics. As the material used for the resin component 18, polymer resins are preferred, such as polypropylene (PP) resin and polybutylene terephthalate (PBT) resin.

[0024] As described above, in the cylindrical battery 10, even after the fracture of the fragile portion 16 caused by an increase in internal battery pressure, the internal sealing of the battery is ensured. If the internal battery pressure increases further, then... Figure 2As shown, the resin component 18 deforms outward from the battery, including a portion of the outer end plate 13 that is cut off from the metal component 12 along the breakable portion 16. This constitutes a current-cutting mechanism, such that the current path between the center of the metal component 12 connecting the external leads and the positive lead 21a is cut off. If the internal pressure of the battery further increases, as... Figure 3 As shown, a portion of the resin component 18 breaks. This constitutes a gas venting mechanism, allowing gas inside the battery to be released. The strength of the resin component 18 can be adjusted according to the material and thickness, but it is also possible to provide a easily breakable portion, such as an annular groove, in the resin component 18.

[0025] The current cut-off mechanism and gas venting mechanism described above will be explained in further detail. The internal battery pressure when the fracturing part 16 breaks is set as P1, the internal battery pressure when the resin component 18 breaks is set as P2, and the internal battery pressure when the resin component 18 detaches from the metal component 12 is set as P3. In this case, the fracture strength of the fracturing part 16 and the resin component 18, as well as the fixing strength of the metal component 12 to the resin component 18, are limited so that the relationship P1 < P2 < P3 holds. When the internal battery pressure reaches P1, even if only a portion of the fracturing part 16 breaks, the resin component 18 will deform outwards from the battery, thus allowing the portion connecting the external lead to be cut along the fracturing part 16 and the metal component 12. If the internal battery pressure rises to P2 after the fracturing part 16 breaks, the resin component 18 breaks, and the gas inside the battery is vented. Furthermore, the fracture strength of the fracturing part 16 and the resin component 18, as well as the fixing strength of the metal component 12 to the resin component 18, can also be limited so that the relationship P1 < P3 < P2 holds. Similarly, in this case, the portion connecting the external lead can be cut off along the breakable portion 16 and the metal component 12. If the internal pressure of the battery rises to P3 after the breakable portion 16 breaks, the front end of the resin component 18 will detach from the metal component 12, and the gas inside the battery will be released. In the above relationship, P2 and P3 can also satisfy the relationship P2 = P3.

[0026] The fracture-prone portion 16 is preferably formed in an annular shape. Alternatively, an annular fracture-prone portion can be formed by a stepped portion whose thickness varies radially in the inner end plate portion 15. Within the range achievable by the current cutting mechanism, the fracture-prone portion 16 can also be partially discontinuous in a C-shape. The fracture strength of the resin component 18 can be adjusted according to its material and thickness, and a fracture-prone portion can also be formed in the resin component 18. The fracture-prone portion of the resin component 18 can be formed, for example, by an annular or C-shaped groove. Alternatively, a fracture-prone portion can be formed by a stepped portion whose thickness varies radially in the resin component 18. The fixing strength of the metal component 12 to the resin component 18 can be adjusted according to the stamping pressure during the compression of the resin component 18.

[0027] Next, the electrode body 20 will be described. The electrode body 20 is disposed inside the outer packaging container 100. The positive electrode plate 21 constituting the electrode body 20 has a positive current collector and a positive active material layer formed on the positive current collector. For example, the positive active material layer is formed on both sides of the positive current collector. The positive current collector may be, for example, a foil of a metal such as aluminum, or a film with that metal deposited on the surface. Preferably, the positive current collector is a foil of a metal with aluminum or an aluminum alloy as the main component. The thickness of the positive current collector is, for example, 10 μm to 30 μm.

[0028] The positive electrode active material layer preferably includes a positive electrode active material, a conductive agent, and a binder. The positive electrode plate 21 is manufactured by applying a positive electrode mixture slurry, including a positive electrode active material, a conductive agent, a binder, and a dispersion medium such as N-methyl-2-pyrrolidone (NMP), to both sides of the positive electrode current collector, followed by drying and calendering.

[0029] Examples of lithium-containing transition metal composite oxides containing transition metal elements such as Co, Mn, and Ni can be cited as positive electrode active materials. While not particularly limited to lithium-containing transition metal composite oxides, those with the general formula Li are preferred. 1+x A composite oxide represented by MO2 (where -0.2 < x ≤ 0.2, and M includes at least one of Ni, Co, Mn, and Al).

[0030] Examples of the aforementioned conductive agents include carbon black (CB), acetylene black (AB), Ketjen black, graphite, and other carbon materials. Examples of the aforementioned adhesives include fluorinated resins such as polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVdF), polyacrylonitrile (PAN), polyimide (PI), acrylic resins, and polyolefin resins. Furthermore, these resins can be used in conjunction with carboxymethyl cellulose (CMC) or its salts, polyethylene oxide (PEO), etc. These substances can be used individually or in combination of two or more.

[0031] A positive current collector exposed portion (not shown) is provided on the positive electrode plate 21, which exposes the surface of the metal constituting the positive current collector. This exposed portion is the part connecting the positive electrode lead 21a, and is the part of the positive current collector surface not covered by the positive active material layer. One end of the positive electrode lead 21a is joined to the exposed portion, for example, by ultrasonic welding. The other end of the positive electrode lead 21a extends upward through an opening (not shown) formed in the circular first insulating plate 30 disposed on the upper side of the electrode body 20, thereby connecting to the lower surface (inner surface) of the flange portion 15a of the metal component 12. The material of the positive electrode lead 21a may include, for example, aluminum, aluminum alloy, nickel, nickel alloy, iron, stainless steel, etc.

[0032] The negative electrode plate 22 has a negative current collector and a negative active material layer formed on the negative current collector. For example, the negative active material layer is formed on both sides of the negative current collector. Furthermore, the negative electrode plate 22 has a negative current collector exposed portion (not shown) at the winding end. The negative current collector exposed portion is the part that connects to the negative lead 22a, and is the part of the surface of the negative current collector that is not covered by the negative active material layer. One end of the negative lead 22a is joined to the negative current collector exposed portion, for example, by ultrasonic welding. The other end of the negative lead 22a passes through the outer periphery of the circular plate-shaped second insulating plate 31 disposed on the lower side of the electrode body 20 and is connected to the bottom of the outer packaging can 100.

[0033] The negative electrode active material layer preferably includes a negative electrode active material and a binder. For example, the negative electrode plate 22 is manufactured by applying a negative electrode mixture slurry, including a negative electrode active material, a binder and water, to both sides of the negative electrode current collector, followed by drying and calendering.

[0034] As the negative electrode active material, any material capable of reversibly absorbing and releasing lithium ions is not particularly limited. Examples include carbon materials such as natural graphite and artificial graphite, metals alloyed with lithium such as Si and Sn, or alloys and composite oxides containing these materials. The binder included in the negative electrode active material layer may be the same resin used in the case of the positive electrode plate 21. When preparing the negative electrode slurry using an aqueous solvent, styrene-butadiene rubber (SBR), CMC or its salts, polyacrylic acid or its salts, polyvinyl alcohol, etc., may be used. These materials may be used individually or in combination of two or more.

[0035] The negative electrode plate 22 is wound and used while being stacked on top of the positive electrode plate 21 with the separator 23 in between. Alternatively, a negative electrode lead 22a can be used, or the negative electrode lead 22a can be omitted, and a negative electrode current collector exposed portion can be arranged on the entire circumference of the outermost peripheral surface of the winding end of the negative electrode plate 22, so that the exposed portion of the negative electrode current collector contacts the inner peripheral surface of the cylindrical portion of the outer packaging can 100, thereby electrically connecting the negative electrode plate 22 to the outer packaging can 100. This ensures better current collection performance. In this case, one end of the negative electrode lead 22a can also be joined to the exposed portion of the negative electrode current collector formed at the winding start end of the negative electrode plate 22.

[0036] The separator 23 is a porous sheet with ion permeability and insulation. Specific examples of porous sheets include microporous films, fabrics, and nonwoven fabrics. The material of the separator 23 is preferably a polyolefin resin such as polyethylene or polypropylene. The thickness of the separator 23 is, for example, 10 μm to 50 μm. The separator 23 tends to be made of thin film as batteries increase in capacity and output. The separator 23 has, for example, a melting point of about 130°C to 180°C.

[0037] The cylindrical battery 10 is assembled as follows. For example, the electrode body 20 and the lower circular plate-shaped second insulating plate 31 are inserted into the inside of a bottomed cylindrical outer can 100, which is made by deep drawing a steel plate. The negative electrode lead 22a, which is connected to the negative electrode plate 22, is welded to the bottom of the outer can 100. Next, the circular plate-shaped first insulating plate 30 is inserted into the upper side of the electrode body 20 inside the outer can 100. On the opening side of the outer can 100, which is higher than the first insulating plate 30, a U-shaped groove 101 is formed circumferentially by plastic forming. Figure 1 Then, a given amount of the prepared non-aqueous electrolyte is injected into the outer can 100 into which the electrode body 20 is placed. Furthermore, the positive electrode lead 21a, which is connected to the positive electrode plate 21, is welded to the flange portion 15a of the metal component 12 constituting the sealing body 11. At this time, the resin component 18 is pre-riveted and fixed to the outer periphery of the metal component 12. For example, a stamping process is performed to compress the resin component 18 through the inner end plate portion 15 and the outer end plate portion 13 of the metal component 12, thereby riveting and fixing the resin component 18 to the metal component 12. Furthermore, while folding the positive electrode lead 21a, the metal component 12 is accommodated on the groove portion 101 via the resin component 18 inside the outer can 100, and the open end of the outer can 100 is riveted, thereby producing a sealed cylindrical battery 10. At this time, the outer end plate portion 13 is exposed at the uppermost part of the cylindrical battery 10 at the upper end of the sealing body 11.

[0038] Alternatively, the resin component 18 and the metal component 12 can be arranged inside one end of the outer can 100 without being riveted, and the outer periphery of the metal component 12 can be riveted to one end of the outer can 100 via the resin component 18. Furthermore, a stamping process can be performed thereafter to compress the resin component 18 via the inner end plate 15 and the outer end plate 13.

[0039] According to the cylindrical battery 10 described above, the metal component 12 constituting the sealing body 11 can have a current cutting function, thus reducing the number of components constituting the sealing body 11. This reduces the machining time for components requiring high machining precision, thereby lowering manufacturing costs.

[0040] Figure 4 This is a cross-sectional view of the comparative example cylindrical battery 10a. The comparative example cylindrical battery 10a and... Figures 1-3Unlike the cylindrical battery 10 shown, the sealing structure at one end of the outer can 100a includes a gasket 34 as a resin component and a sealing body 11a. The sealing body 11a comprises three components: a metal valve body 36, an insulating member 38, and a metal body 40 with vent holes. The valve body 36 and the metal body 40 are connected to each other at their center portions, with the insulating member 38 sandwiched between their outer peripheries. The end of the positive electrode lead 21a, extending from the electrode body 20, is radially outward from the connection between the valve body 36 and the metal body 40, and connects to the metal body 40. The connection between the metal body 40 and the valve body 36 is a thin-walled portion. If the internal pressure of the battery increases, the valve body 36 deforms upward under the internal pressure, thereby stretching the connection between the valve body 36 and the metal body 40 outward from the battery. This connection, or the thin-walled portion of the metal body 40, may break, cutting off the current path between the valve body 36 and the positive electrode lead 21a. Furthermore, if the internal pressure of the battery rises, the thin-walled portion 36a of the valve body 36 becomes the starting point, the valve body 36 breaks, and the gas inside the battery is released. In the cylindrical battery 1Oa of the comparative example described above, since the number of components for providing the current cut-off function in the sealing body 11a increases to three, it becomes a significant burden during processing, increasing the manufacturing time considerably. Figures 1-3 The implementation method can prevent the aforementioned adverse situations.

[0041] -Symbol Explanation-

[0042] 10, 10a Cylindrical battery; 11, 11a Sealing body; 12 Metal component; 12a Slot; 13 Outer end plate; 15 Inner end plate; 15a Flange; 15b Slot; 17 Connecting part; 18 Resin component; 20 Electrode body; 21 Positive electrode plate; 21a Positive electrode lead; 22 Negative electrode plate; 22a Negative electrode lead; 23 Separator; 30 First insulating plate; 31 Second insulating plate; 34 Gasket; 36 Valve body; 36a Thin-walled part; 38 Insulating component; 40 Metal body.

Claims

1. A cylindrical battery, comprising: A bottomed cylindrical outer packaging can; A sealing body that blocks one end of the outer can; Electrodes disposed inside the outer can; and An insulating resin component disposed between the outer can and the sealing body. The sealing body has a metal component that is electrically connected to the electrode leads extending from the electrode body. The metal component has a fracture-prone portion further radially inward than the connection between the metal component and the electrode lead, and is riveted and fixed via the resin component and the outer can. The resin component is riveted and fixed to the metal component on the inner side of the metal component in the radial direction, which is closer to the easily breakable part. The metal component has an inner end plate portion, an outer end plate portion, and a connecting portion connecting the inner end plate portion and the outer end plate portion. The radially outer flange portion of the inner end plate is riveted and fixed to one end of the outer can via the resin component. The front end of the resin component, which extends from between the flange and one end of the outer can, is riveted to the inner end plate and the outer end plate.

2. The cylindrical battery according to claim 1, wherein, The easily fractured portion is formed by annular grooves.

3. The cylindrical battery according to claim 1 or 2, wherein, The cylindrical battery is configured such that, when the internal pressure of the battery increases, the fractured portion breaks throughout the entire circumference, the current path between the center of the metal component and the electrode lead is cut off, and when the internal pressure of the battery increases further, the outer portion of the fractured portion breaks in the resin component, thereby releasing the internal gas.

4. The cylindrical battery according to claim 1 or 2, wherein, The cylindrical battery is configured such that, when the internal pressure of the battery increases, the fractured portion breaks throughout the entire circumference, the current path between the center of the metal component and the electrode lead is cut off, and when the internal pressure of the battery increases further, the front end of the resin component detaches from the metal component, thereby releasing the internal gas.

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