Cylindrical battery

Abstract

A cylindrical battery (10) is provided with: an electrode body (14) in which a positive electrode (11) and a negative electrode (12) are wound with a separator (13) interposed therebetween; a bottomed cylindrical outer can (16) that houses the electrode body (14); a sealing body (17) that seals the opening of the outer can (16); and an insulating plate (18) that is disposed between the sealing body (17) and the electrode body (14) in the axial direction. The sealing body (17) includes a sealing plate (27) constituting a safety valve. The insulating plate (18) has a breakable section. The easy-to-break portion provided on the insulating plate (18) may be of any structure in which the exhaust path can be secured by breaking the easy-to-break portion.

Description

Technical Field

[0001] The present application relates to a cylindrical battery. Background Art

[0002] Conventionally, as a cylindrical battery, there is the cylindrical battery described in Patent Document 1. The cylindrical battery includes an electrode body, a bottomed cylindrical outer packaging can that houses the electrode body, a sealing body that seals the opening of the outer packaging can, and an insulating plate that is axially disposed between the electrode body and the sealing body. The sealing body includes a safety valve that discharges the gas inside the battery to the outside by breaking when the pressure inside the battery rises after abnormal heating of the battery. The insulating plate has a through hole, and a positive electrode lead wire led out from the electrode body passes through the through hole and is joined to the lower surface of the sealing body. The insulating plate prevents a short circuit between the positive electrode and the negative electrode.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Patent Laid-Open No. 09-306469 Summary of the Invention

[0006] If a melt such as a spacer generated due to abnormal heating of the battery blocks at least a part of the through hole provided in the insulating plate, the exhaust path for discharging the gas inside the battery becomes narrow, and it may not be possible to exhaust the gas smoothly. Therefore, the cylindrical battery of the present application provides a cylindrical battery that can easily ensure the exhaust path for the gas inside the battery and improve safety in the case of abnormal heating of the battery.

[0007] To solve the above problems, the cylindrical battery of the present application includes an electrode body formed by winding a positive electrode and a negative electrode with a spacer interposed therebetween, a bottomed cylindrical outer packaging can that houses the electrode body, a sealing body that seals the opening of the outer packaging can, and an insulating plate that is axially disposed between the sealing body and the electrode body. The sealing body includes a safety valve, and the insulating plate has a fracture-prone portion.

[0008] According to the cylindrical battery of the present application, in the case of abnormal heating of the battery, it is easy to ensure the exhaust path for the gas inside the battery, and safety can be improved. Brief Description of the Drawings

[0009] Figure 1 is an axial sectional view of a cylindrical battery according to an embodiment of the present application.

[0010] Figure 2 is a perspective view of the electrode body.

[0011] Figure 3 is Figure 1 an enlarged sectional view around the sealing body of

[0012] Figure 4 It is a schematic perspective view when observing the insulating plate obliquely from above.

[0013] Figure 5 It is the schematic perspective view corresponding to Figure 4 of the insulating plate of the first modification.

[0014] Figure 6 It is the schematic perspective view corresponding to Figure 4 of the insulating plate of the second modification. Detailed implementation mode

[0015] Hereinafter, while referring to the drawings, the implementation mode of the cylindrical battery of the present application will be described in detail. It should be noted that the cylindrical battery of the present application can be a primary battery or a secondary battery. In addition, it can be a battery using an aqueous electrolyte or a battery using a non-aqueous electrolyte. Hereinafter, regarding the cylindrical battery 10 as one implementation mode, a non-aqueous electrolyte secondary battery (lithium ion battery) using a non-aqueous electrolyte is illustrated, however, the cylindrical battery of the present application is not limited thereto.

[0016] It is initially contemplated to appropriately combine the characteristic parts of the implementation modes and modification examples described below to construct a new implementation mode. In the following implementation modes, the same reference numerals are given to the same components in the drawings, and repeated descriptions are omitted. In addition, among the multiple drawings, there are schematic diagrams, and the longitudinal, transverse, height, etc. dimensional ratios of each component may not be the same between different drawings. In this specification, the side of the sealing body 17 in the axial direction (height direction) of the cylindrical battery 10 is set as "upper", and the side of the bottom 68 of the outer packaging can 16 in the axial direction is set as "lower". In addition, among the components described below, regarding the components not described in the independent claims representing the uppermost concept, they are optional components and not essential components.

[0017] Figure 1 It is an axial sectional view of the cylindrical battery 10 of one implementation mode of the present application. As Figure 1 shown, the cylindrical battery 10 includes a wound electrode body 14, a non-aqueous electrolyte (not shown), a bottomed cylindrical outer packaging can 16 for housing the electrode body 14 and the non-aqueous electrolyte, and a sealing body 17 for sealing the opening of the outer packaging can 16. The electrode body 14 has a positive electrode 11, a negative electrode 12, and a spacer 13 interposed between the positive electrode 11 and the negative electrode 12. The cylindrical battery 10 further includes a resin gasket 28 disposed between the outer packaging can 16 and the sealing body 17.

[0018] The non-aqueous electrolyte contains a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. As the non-aqueous solvent, for example, esters, ethers, nitriles, amides, and a mixed solvent of two or more thereof can be used. The non-aqueous solvent may contain a halogen-substituted product in which at least a part of the hydrogen atoms of these solvents is substituted with a halogen atom such as fluorine. It should be noted that the non-aqueous electrolyte is not limited to a liquid electrolyte, and may also be a solid electrolyte using a gelled polymer or the like. As the electrolyte salt, a lithium salt such as LiPF6 is used.

[0019] Figure 2 is a perspective view of the electrode body 14. As Figure 2 shown, the electrode body 14 has a winding structure in which a long strip-shaped positive electrode 11, a long strip-shaped negative electrode 12, and two long strip-shaped spacers 13 are provided, and the positive electrode 11 and the negative electrode 12 are wound with the spacers 13 interposed therebetween. A positive electrode lead 20 is joined to the positive electrode 11, and a negative electrode lead 21 is joined to the negative electrode 12. In order to suppress the precipitation of lithium, the negative electrode 12 is formed in a size one circle larger than the positive electrode 11, that is, the negative electrode 12 is formed longer than the positive electrode 11 in the length direction and the width direction (short side direction). In addition, the two spacers 13 are formed in a size at least one circle larger than the positive electrode 11, and are arranged, for example, in a manner of sandwiching the positive electrode 11.

[0020] The positive electrode 11 has a positive electrode current collector and positive electrode mixture layers formed on both surfaces of the positive electrode current collector. As the positive electrode current collector, a metal foil such as aluminum or an aluminum alloy that is stable in the potential range of the positive electrode 11, a film having the metal disposed on the surface layer, or the like can be used. The positive electrode mixture layer contains a positive electrode active material, a conductive agent, and a binder. For example, a positive electrode mixture slurry containing a positive electrode active material, a conductive agent, and a binder is coated on the positive electrode current collector, and after the coating film is dried, it is compressed to form positive electrode mixture layers on both surfaces of the positive electrode current collector, whereby the positive electrode 11 can be manufactured.

[0021] The positive electrode active material is mainly composed of a lithium-containing metal composite oxide. As the metal elements contained in the lithium-containing metal composite oxide, Ni, Co, Mn, Al, B, Mg, Ti, V, Cr, Fe, Cu, Zn, Ga, Sr, Zr, Nb, In, Sn, Ta, W, etc. can be cited. An example of a preferred lithium-containing metal composite oxide is a composite oxide containing at least one of Ni, Co, Mn, and Al.

[0022] As the conductive agent contained in the positive electrode mixture layer, carbon materials such as carbon black, acetylene black, Ketjen black, and graphite can be exemplified. As the binder contained in the positive electrode mixture layer, fluororesins such as polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVdF), polyacrylonitrile (PAN), polyimide resin, acrylic resin, polyolefin resin, etc. can be exemplified. These resins and cellulose derivatives such as carboxymethyl cellulose (CMC) or its salts, polyethylene oxide (PEO), etc. can also be used in combination.

[0023] The negative electrode 12 has a negative electrode current collector and negative electrode mixture layers formed on both sides of the negative electrode current collector. As the negative electrode current collector, metal foils that are stable in the potential range of the negative electrode 12, such as copper and copper alloys, and films with such metals disposed on the surface layer can be used. The negative electrode mixture layer contains a negative electrode active material and a binder. For example, a negative electrode mixture slurry containing a negative electrode active material, a binder, etc. is coated on the negative electrode current collector, and after the coating film is dried, it is compressed to form negative electrode mixture layers on both sides of the negative electrode current collector, whereby the negative electrode 12 can be fabricated.

[0024] As the negative electrode active material, carbon materials that reversibly store and release lithium ions are generally used. Preferred carbon materials are natural graphites such as flake graphite, massive graphite, and earthy graphite, artificial graphites such as massive artificial graphite and graphitized mesophase carbon microspheres, etc. Graphite. In the negative electrode mixture layer, a Si material containing silicon (Si) can also be included as the negative electrode active material. In addition, as the negative electrode active material, metals that alloy with lithium other than Si, alloys containing such metals, compounds containing such metals, etc. can also be used.

[0025] As in the case of the positive electrode 11, the binder contained in the negative electrode mixture layer can be a fluororesin, PAN, polyimide resin, acrylic resin, polyolefin resin, etc., and styrene-butadiene rubber (SBR) or its modified product is preferably used. In the negative electrode mixture layer, for example, CMC or its salt, polyacrylic acid (PAA) or its salt, polyvinyl alcohol, etc. can also be included on the basis of SBR, etc.

[0026] The spacer 13 can be a porous sheet having ion permeability and insulation. Specific examples of the porous sheet include microporous films, woven fabrics, non-woven fabrics, etc. As the material of the spacer 13, polyolefin resins such as polyethylene and polypropylene, cellulose, etc. are preferred. The spacer 13 can be either a single-layer structure or a laminated structure. A heat-resistant layer, etc. can be formed on the surface of the spacer 13.

[0027] Figure 1 and Figure 2In the example shown, the positive electrode lead 20 is electrically connected to an intermediate portion such as the central portion in the winding direction of the positive electrode core body, and the negative electrode lead 21 is electrically connected to the winding end portion in the winding direction of the negative electrode core body. However, the negative electrode lead may also be electrically connected to the winding start end portion in the winding direction of the negative electrode core body. Alternatively, the electrode body may have two negative electrode leads, one negative electrode lead being electrically connected to the winding start end portion in the winding direction of the negative electrode core body, and the other negative electrode lead being electrically connected to the winding end portion in the winding direction of the negative electrode core body. Alternatively, the negative electrode lead may be electrically connected to the winding start end portion in the winding direction of the negative electrode core body, and the winding end side portion in the winding direction of the negative electrode core body may be brought into contact with the inner surface of the outer packaging can. Alternatively, there may be no negative electrode lead, but the winding end side portion in the winding direction of the negative electrode core body may be brought into contact with the inner surface of the outer packaging can, thereby electrically connecting the negative electrode to the outer packaging can.

[0028] As Figure 1 shown, the cylindrical battery 10 further includes an insulating plate 18 disposed on the upper side of the electrode body 14 and an insulating plate 19 disposed on the lower side of the electrode body 14. The insulating plates 18 and 19 are made of a material having insulating properties, such as resin. Figure 1 In the example shown, the positive electrode lead 20 mounted on the positive electrode 11 passes through the through hole of the insulating plate 18 and extends toward the sealing body 17 side, and the negative electrode lead 21 mounted on the negative electrode 12 passes outside the insulating plate 19 and extends toward the bottom 68 side of the outer packaging can 16. The positive electrode lead 20 is joined to the lower surface of the terminal plate 23 which is the bottom plate of the sealing body 17 by welding or the like, and the sealing plate 27 which is the top plate of the sealing body 17 and is electrically connected to the terminal plate 23 becomes the positive electrode terminal. In addition, the negative electrode lead 21 is connected to the inner surface of the bottom 68 of the outer packaging can 16 by welding or the like, and the outer packaging can 16 becomes the negative electrode terminal.

[0029] The outer packaging can 16 is a bottomed cylindrical metal container having a cylindrical portion 30 and a bottom 68. The space between the outer packaging can 16 and the sealing body 17 is sealed by a ring-shaped gasket 28, thereby sealing the internal space of the cylindrical battery 10. The gasket 28 is clamped between the outer packaging can 16 and the sealing body 17, insulating the sealing body 17 from the outer packaging can 16. The gasket 28 functions as a sealing material for ensuring the airtightness inside the battery and as an insulating material for preventing a short circuit between the outer packaging can 16 and the sealing body 17.

[0030] The outer packaging can 16 has an annular slotted portion 35 in a part of the axial direction of the cylindrical portion 30. The slotted portion 35 can be formed, for example, by spinning a part of the cylindrical portion 30 radially inward to make it recessed radially inward. The cylindrical portion 30 has the slotted portion 35 and an annular shoulder portion 33. The shoulder portion 33 is bent radially inward from the end portion on the opening side of the cylindrical portion 30 and extends radially inward. The shoulder portion 33 is formed when the upper end portion of the outer packaging can 16 is bent inward and caulked to the peripheral portion 31 of the sealing body 17. Due to this caulking, the sealing body 17 is clamped and fixed to the outer packaging can 16 with the shoulder portion 33 and the slotted portion 35 sandwiching the gasket 28.

[0031] Next, the structure, current blocking action, and gas release action of the sealing body 17 will be described. Figure 3 It is an enlarged cross-sectional view of the periphery of the sealing body of the cylindrical battery 10. As Figure 3 shown, the sealing body 17 has a structure in which a terminal plate 23, an annular insulating plate 25, and a sealing plate 27 are laminated in sequence from the electrode body 14 side. Each member constituting the sealing body 17 has a disc shape or an annular shape, and the members other than the insulating plate 25 are electrically connected. The terminal plate 23 constitutes the bottom plate of the sealing body 17. The terminal plate 23 has an annular thick wall portion 23a located on the radially outer side, and a disc-shaped thin wall portion 23b connected to the annular end portion on the radially inner side of the thick wall portion 23a and thinner than the thick wall portion 23a. The positive electrode lead 20 is connected to the lower surface of the thick wall portion 23a of the terminal plate 23 by welding or the like.

[0032] The sealing plate 27 is circular in plan view and has a central portion 27a, an outer peripheral portion 27b, and an inclined portion 27c connecting the central portion 27a and the outer peripheral portion 27b. The upper surface of the thin wall portion 23b of the terminal plate 23 and the lower surface of the central portion 27a of the sealing plate 27 are joined by metallurgical bonding, for example, laser welding. The thickness of the inclined portion 27c is thinner than that of the central portion 27a. The annular upper surface of the inclined portion 27c becomes an inclined surface that gradually lies on the upper side as it proceeds radially outward, and the annular lower surface of the inclined portion 27c also becomes an inclined surface that gradually lies on the upper side as it proceeds radially outward. The thickness of the inclined portion 27c gradually decreases as it proceeds radially outward.

[0033] The insulating plate 25 is embedded and fixed to the inner peripheral surface of the outer peripheral portion 27b, for example, by press-fitting. The insulating plate 25 has an annular protruding portion 25a that bends downward in the axial direction on the outer peripheral side in the radial direction. The thick-walled portion 23a of the terminal plate 23 is embedded and fixed to the inner peripheral surface of the annular protruding portion 25a, for example, by press-fitting. The insulating plate 25 is made of an insulating resin or the like to prevent the thick-walled portion 23a of the terminal plate 23 from being electrically connected to the sealing plate 27. The insulating plate 25 has one or more air-permeable holes 25b that penetrate in the axial direction at a portion that axially overlaps with the inclined portion 27c of the sealing plate 27. The terminal plate 23 has one or more air-permeable holes 23c that penetrate in the axial direction and communicate with the air-permeable holes 25b at a portion that axially overlaps with the inclined portion 27c.

[0034] Figure 4 It is a schematic perspective view when observing the insulating plate 18 obliquely from above. As Figure 4 shown, the insulating plate 18 has a breakable portion 41 formed by a notch provided within a range that does not penetrate in the thickness direction. The breakable portion 41 includes a concentric circle extending portion 41a located on a circle that is substantially concentric with the inner peripheral circle of the outer packaging can 16. In the present embodiment, the concentric circle extending portion 41a has a C shape in a plan view when observing the insulating plate 18 from the axial direction, and both ends of the concentric circle extending portion 41a are connected to a through hole 45 through which the positive electrode lead 20 passes in the insulating plate 18. It should be noted that only one end of the concentric circle extending portion may be connected to the through hole through which the positive electrode lead passes, or both ends of the concentric circle extending portion may not be connected to the through hole through which the positive electrode lead passes. In addition, the insulating plate 18 has a through hole 46 at the central portion. The through hole 46 is provided for the purpose of allowing the electrolyte to flow smoothly toward the electrode body 14 during liquid injection, etc. However, the insulating plate may not have a through hole at the center.

[0035] In the above configuration, when the cylindrical battery 10 abnormally heats up and the internal pressure of the cylindrical battery 10 reaches a specified value, the following current interruption operation and gas release operation are performed. Specifically, when the internal pressure of the cylindrical battery 10 reaches the specified value, with the annular end portion 39 on the radially outer side with low rigidity as a fulcrum at the inclined portion 27c, the central portion 27a and the inclined portion 27c of the sealing plate 27 flip upward in the axial direction. At the same time as this flipping, the thin-walled portion 23b of the terminal plate 23 or the welded portion between the terminal plate 23 and the sealing plate 27 breaks, separating the sealing plate 27 from the terminal plate 23. Through this operation, the current path between the terminal plate 23 and the sealing plate 27 is interrupted.

[0036] When the internal pressure further rises, the annular end portion 39 of the inclined portion 27c (refer to Figure 3When it breaks, the gas inside the battery is discharged to the outside from the broken part of the sealing plate 27 through the vent hole 23c and the vent hole 25b. Thus, even if the internal pressure of the cylindrical battery 10 rises, the battery can be prevented from bursting, the influence on the device equipped with the cylindrical battery 10 can be suppressed, and the safety can be improved. As described above, the sealing plate 27 constitutes a safety valve. In the present embodiment, the sealing plate 27 constituting the safety valve is provided at the upper end of the sealing body 17. However, a terminal cover having a vent hole may be arranged above the sealing plate 27.

[0037] However, when the melt of the spacer or the like generated due to the abnormal heating of the cylindrical battery 10 blocks part or all of the through holes 45 and 46 of the insulating plate 18, the through holes 45 and 46 of the insulating plate 18 are blocked, and a sufficient exhaust path from the electrode body 14 to the sealing body 17 cannot be ensured. In the cylindrical battery 10 of the present application, when the through holes 45 and 46 of the insulating plate 18 are blocked, the easily breakable part 41 of the insulating plate 18 breaks, and through this break, a sufficient exhaust path from the electrode body 14 to the sealing body 17 is formed. Therefore, in the cylindrical battery 10 of the present application, even if the through holes 45 and 46 of the insulating plate 18 are blocked, it is possible to prevent the internal pressure of the space on the electrode body 14 side of the insulating plate 18 in the outer packaging can 16 from becoming too high. Thus, it is possible to reliably prevent the side wall of the outer packaging can 16 other than the safety valve from breaking, and high safety during abnormal heating of the cylindrical battery 10 can be achieved.

[0038] Preferably, like the present embodiment, the concentric circle extension part 41a has a C shape in a plan view when the insulating plate 18 is viewed from the axial direction. Thus, it becomes easy to ensure the exhaust path. When viewed from the axial direction, the area of the insulating plate 18 is preferably 20% or more and 95% or less of the inner diameter area surrounded by the inner circumference circle 48 of the part that faces the upper end face of the electrode body 14 in the outer packaging can 16 in the radial direction. The area of the insulating plate 18 is the area of the part obtained by removing the through holes 45 and 46 from the range surrounded by the outer circumference of the insulating plate 18.

[0039] The easily breakable part 41 of the insulating plate 18 only needs to break before the parts other than the safety valve of the cylindrical battery 10 break, and the operating pressure at which the easily breakable part 41 breaks can be adjusted based on the depth of the notch formed in the insulating plate 18. In order to ensure the breakability of the easily breakable part 41 while also ensuring the strength of the insulating plate 18, the depth of the notch is preferably 15% to 90% of the thickness of the insulating plate 18, and more preferably 20% to 80% of the thickness of the insulating plate 18.

[0040] It should be noted that the present application is not limited to the above-described embodiments and their modified examples, and various improvements and changes can be made within the scope of the matters described in the technical solution of the present application and their equivalent scope.

[0041] In the above embodiment, the easily breakable portion 41 includes the concentric circle extension portion 41a located on a circle substantially concentric with the inner circumference of the outer can 16 in the top view when the insulating plate 18 is viewed from the axial direction, and the insulating plate 18 is broken along the concentric circle extension portion 41a. However, the easily breakable portion provided in the insulating plate may have any structure as long as the exhaust path can be ensured by its breaking.

[0042] For example, you can also Figure 5 , that is, the insulating plate 118 of the first modification example and Figure 4 As shown in the corresponding schematic perspective view, the easily breakable portion 141 includes a plurality of radially extending portions 141a extending radially from a central position substantially located in the radial center of the outer can 16. If the easily breakable portion 141 is formed in this way, the insulating plate 118 can be broken radially.

[0043] Alternatively, you can Figure 6 , that is, the insulating plate 218 of the second modification example and Figure 4 As shown in the corresponding schematic stereogram, the easily breakable portion 241 is formed by combining the above-mentioned concentric circular extension portion 41a and the above-mentioned radial extension portion 141a. Alternatively, the easily breakable portion provided on the insulating plate may also include a closed curve portion, for example, a circular closed curve portion formed in a manner of surrounding a through hole for passing the lead wire, or the circular closed curve portion and a straight line portion extending along the diameter and connected to the circular closed curve portion at two locations.

[0044] In the above embodiment, the case where the easily breakable portion 41, 141, 241 is formed by scoring is described. However, the easily breakable portion 41, 141, 241 may be formed by grooves instead of scoring in the insulating plate.

[0045] Description of Reference Numerals

[0046] 10 Cylindrical battery, 11 Positive electrode, 12 Negative electrode, 13 Separator, 14 Electrode body, 16 Outer can, 17 Sealing body, 18, 19, 118, 218 Insulating plate, 20 Positive electrode lead, 21 Negative electrode lead, 23 Terminal plate, 23a Thick wall portion, 23b Thin wall portion, 23c Air vent, 25 Insulating plate, 25a Annular protrusion, 25b Air vent, 27 Sealing plate, 27a Central portion, 27b Peripheral portion, 27c Inclined portion, 28 Gasket, 30 Cylindrical portion, 31 Peripheral portion, 33 Shoulder, 35 Grooved portion, 39 Annular end, 41, 141, 241 Easy-to-break portion, 41a Concentric extension portion, 45, 46 Through hole, 48 Inner circumference, 68 Bottom, 141a radial extension.

Claims

1. A cylindrical battery, comprising: An electrode body formed by winding a positive electrode and a negative electrode with a spacer therebetween, A bottomed cylindrical outer packaging can accommodating the electrode body, A sealing body for sealing an opening of the outer packaging can, and An insulating plate axially disposed between the sealing body and the electrode body, The sealing body includes a safety valve, The insulating plate has a breakable portion.

2. The cylindrical battery according to claim 1, wherein When viewed from the axial direction, the area of the insulating plate is 20% or more and 95% or less of the inner diameter area surrounded by the inner circumference of the portion facing the end face on the sealing body side of the electrode body in the outer packaging can in the radial direction.

3. The cylindrical battery according to claim 1 or 2, wherein The breakable portion is formed by a notch provided within a range that does not penetrate in the thickness direction of the insulating plate.

4. The cylindrical battery according to claim 1 or 2, wherein The breakable portion includes a concentric circle extending portion extending along a circle substantially concentric with the inner circumference of the outer packaging can.

5. The cylindrical battery according to claim 1 or 2, wherein The breakable portion includes a plurality of radially extending portions radially extending in a substantially radial direction from a central position located substantially at the center in the radial direction of the outer packaging can.

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