Cylindrical battery
The cylindrical battery design with an annular thin-walled filter plate rupture and insulating layers addresses the incomplete current interruption issue, ensuring safe operation by preventing short circuits and enhancing exhaust performance.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD
- Filing Date
- 2025-12-25
- Publication Date
- 2026-07-02
Smart Images
Figure JP2025045569_02072026_PF_FP_ABST
Abstract
Description
Cylindrical battery
[0001] This disclosure relates to a cylindrical battery.
[0002] Conventionally, a cylindrical battery has been known that includes an electrode body in which a positive electrode and a negative electrode are wound with a separator interposed therebetween, and a bottomed cylindrical container that houses the electrode body and an electrolyte. Also, the opening at the upper end of the container is closed with a sealing body in which a cap and a filter plate are integrated, a lead terminal extending upward from the electrode body is welded to the filter plate, and an exhaust structure is provided on the bottom surface of the container. When the internal pressure rises due to an abnormality in the battery, a structure for exhausting from the lower side is considered. The sealing body is caulked and fixed to the opening of the container via a gasket.
[0003] In Patent Document 1, the opening at the upper end of the container that houses the electrode body is closed with a sealing body in which a cap and a bending member are integrated. When the internal pressure of the battery rises, the bending member is deformed upward, and the positive electrode lead terminal is separated from the lower side of the bending member to cut off the current.
[0004] Japanese Patent Application Publication No. 2022-538960
[0005] In the cylindrical battery in which the exhaust structure is provided on the bottom surface of the container as described above and the sealing body is caulked and fixed to the upper end opening of the container, when the internal pressure rises due to an abnormality and a part of the sealing body breaks to provide a gas escape portion, the current is not completely cut off unless the welded portion between the filter plate and the lead terminal comes off or the connection between the bottom of the container and other lead terminals comes off.
[0006] The configuration described in Patent Document 1 is a structure in which the space between the cap and the bending member is widened to cut off the current due to the increase in the internal pressure on the sealing body side, and there is no disclosure about the above-mentioned inconvenience.
[0007] An object of the cylindrical battery of the present disclosure is to enable current interruption by breaking the sealing body even if the welded portion between the lead terminal and the filter plate does not come off in a configuration in which an exhaust structure is provided on the bottom surface of the container.
[0008] The cylindrical battery according to this disclosure comprises an electrode body in which a strip-shaped positive electrode and a strip-shaped negative electrode are wound around a separator, a bottomed cylindrical container housing the electrode body, lead terminals connected to the electrode body and extending upward, a filter plate to which the lead terminals are welded and positioned above the electrode body within the container, and a cap positioned above the filter plate, with its outer peripheral end crimped to the opening of the container via a gasket together with the filter plate to seal the opening, the cylindrical battery having an exhaust structure at the bottom of the container, a space formed between the cap and the filter plate, an annular thin-walled portion formed on the filter plate opposite the space, the thin-walled portion located on the outer peripheral side of the welded portion of the lead terminals of the filter plate, and an insulating layer provided in the portion between the inner surface of the cap and the upper surface of the filter plate that is in contact with the space.
[0009] According to the cylindrical battery described herein, an exhaust structure is provided at the bottom of the container. When the internal pressure of the battery rises, the filter plate ruptures at an annular thin-walled section, and the portion radially inward from the thin-walled section pops out toward the inside of the cap. At this time, even if the lead terminals remain welded to the filter plate, an insulating layer is provided between the inner surface of the cap and the upper surface of the filter plate, thus interrupting the electrical connection between the cap and the lead terminals. As a result, current interruption is possible by the rupture of the sealing body, even if the weld between the lead terminals and the filter plate does not come undone.
[0010] This is a cross-sectional view of the cylindrical battery of the embodiment along the axial direction. This is a perspective view of the electrode body of the cylindrical battery of the embodiment. This is an enlarged view of part A in Figure 1. This figure, corresponding to Figure 1, shows a state in the cylindrical battery of the embodiment where, when the internal pressure rises, a part of the filter plate is pressed against the inside of the cap due to the rupture of the thin-walled portion, and the electrical connection between the cap and the filter plate is interrupted. This figure, corresponding to Figure 4, shows a cylindrical battery of a comparative example.
[0011] Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. In the following description, specific shapes, materials, numerical values, directions, etc., are examples to facilitate understanding of the present invention and can be appropriately modified to suit the specifications of the non-aqueous electrolyte secondary battery. Furthermore, the term "abbreviated" below is used to include, for example, cases where they are exactly the same, as well as cases where they can be considered substantially the same. Moreover, when multiple embodiments and modifications are included below, it is intended from the outset that their characteristic parts may be appropriately combined and used.
[0012] Figure 1 is a cross-sectional view of the cylindrical battery 10 of the embodiment along the axial direction. Figure 2 is a perspective view of the electrode body 14 constituting the cylindrical battery 10. Figure 3 is an enlarged view of part A in Figure 1. Figure 4 is a diagram corresponding to Figure 1, showing a state in the cylindrical battery 10 where, when the internal pressure rises, a part of the filter plate 30 is pressed against the inside of the cap 27 due to the rupture of the thin-walled portion, and the electrical connection between the cap 27 and the filter plate 30 is interrupted. In the following, the case in which the cylindrical battery 10 is a non-aqueous electrolyte secondary battery will be described, but the cylindrical battery 10 can also be applied to configurations other than non-aqueous electrolyte secondary batteries, such as when the electrolyte is aqueous.
[0013] As shown in Figure 1, the cylindrical battery 10 is a non-aqueous electrolyte secondary battery and comprises a wound electrode body 14, a non-aqueous electrolyte (not shown), a container 15, and a sealing body 16. As shown in Figure 2, the wound electrode body 14 has a strip-shaped positive electrode 11, a strip-shaped negative electrode 12, and a separator 13, with the positive electrode 11 and negative electrode 12 wound in a spiral shape via the separator 13. Hereafter, one axial side of the electrode body 14 may be referred to as "up" and the other axial side as "down." Note that "up" and "down" are used for convenience to explain the directional relationship of the cylindrical battery 10 and do not restrict the up and down direction when the cylindrical battery 10 is used. The container 15 is a bottomed cylindrical shape that houses the electrode body 14 and the electrolyte.
[0014] The non-aqueous electrolyte has ionic conductivity (e.g., lithium ion conductivity). The non-aqueous electrolyte comprises a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. The non-aqueous electrolyte is not limited to a liquid electrolyte (non-aqueous electrolyte solution), but may also be a solid electrolyte using a gel-like polymer or the like. The cylindrical battery 10 is preferably a lithium-ion battery. The electrolyte salt may be, for example, LiBF ４ LiPF ６ Lithium salts such as the above are used. Non-aqueous solvents include, for example, esters such as ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), and methyl propionate (MP), as well as ethers, nitriles, amides, and mixed solvents of two or more of these. The non-aqueous solvent may contain halogen-substituted products in which at least some of the hydrogen atoms of these solvents are replaced with halogen atoms such as fluorine.
[0015] Examples of halogen-substituted compounds include fluorinated cyclic carbonates such as fluoroethylene carbonate (FEC), fluorinated linear carbonates, and fluorinated linear carboxylic acid esters such as methyl fluoropropionate (FMP). In terms of suppressing the deterioration of the charge-discharge cycle characteristics of non-aqueous electrolyte secondary batteries or improving the input characteristics, the non-aqueous electrolyte preferably contains 5% by mass or more of FEC relative to the mass of the non-aqueous electrolyte, and more preferably contains 5% to 15% by mass of FEC.
[0016] As solid electrolytes, for example, solid or gel-like polymer electrolytes, inorganic solid electrolytes, etc., are used. Polymer electrolytes include, for example, a lithium salt and a matrix polymer, or a non-aqueous solvent, a lithium salt and a matrix polymer. As matrix polymers, for example, polymer materials that absorb non-aqueous solvents and gel are used. As polymer materials, for example, fluororesins, acrylic resins, polyether resins, etc., are used. As inorganic solid electrolytes, for example, materials known for all-solid-state lithium-ion secondary batteries, etc. (for example, oxide-based solid electrolytes, sulfide-based solid electrolytes, halide-based solid electrolytes, etc.) are used.
[0017] As shown in Figure 2, the positive electrode 11 is electrically connected to the positive electrode lead terminal 20, which is a current collection lead terminal. The positive electrode lead terminal 20 is a conductive member for electrically connecting the positive electrode core, which will be described later and constitute the positive electrode 11, to the positive electrode terminal, and extends from the upper end of the positive electrode core in one axial direction (upwards) of the electrode body 14.
[0018] The negative electrode 12 is formed to be slightly larger than the positive electrode 11 in order to suppress lithium deposition, and is longer than the positive electrode 11 in both the longitudinal and widthwise (short-side) directions. The two separators 13 are also formed to be at least slightly larger than the positive electrode 11 and are arranged to sandwich the positive electrode 11. The separators 13 protrude upward above the positive electrode 11 and the negative electrode 12, while the negative electrode 12 protrudes downward above the positive electrode 11 and the separators 13.
[0019] The negative electrode 12 has an uncoated negative electrode portion 41 at its lower axial end, extending from the beginning end to the end end in the longitudinal direction of the elongated negative electrode 12, where the negative electrode mixture layer 42 is not provided on the negative electrode core body 40. Therefore, the lower axial end of the electrode body 14 is composed of the exposed negative electrode core portion. The negative electrode 12 may also constitute the beginning end of the electrode body 14. However, generally, the separator 13 extends beyond the beginning end of the negative electrode 12, and the beginning end of the separator 13 becomes the beginning end of the electrode body 14. On the other hand, in this example, the negative electrode 12 extends beyond the end end of the separator 13, constituting the end end of the electrode body 14. In this case, the exposed surface of the negative electrode core body 40 exposed on the outermost surface of the negative electrode 12 contacts the inner surface of the container 15 and is electrically connected, thereby increasing the current collection efficiency from the negative electrode 12 to the container 15 which becomes the negative electrode terminal. The cylindrical battery of this disclosure is not limited to this configuration, and may also be configured such that a negative electrode lead terminal is joined to a negative electrode core, and a negative electrode lead terminal extending to the other side (downward) in the axial direction of the negative electrode core is electrically connected to the bottom of the container 15.
[0020] The positive electrode 11 has a strip-shaped positive electrode core and positive electrode mixture layers formed on both sides of the positive electrode core. For the positive electrode core, for example, a metal foil such as aluminum, or a film with the metal arranged on its surface, can be used. A preferred positive electrode core is a metal foil mainly composed of aluminum or an aluminum alloy. The thickness of the positive electrode core is, for example, 10 μm to 30 μm.
[0021] The positive electrode mixture layer preferably contains a positive electrode active material, a conductive agent, and a binder. The positive electrode 11 is manufactured by applying a positive electrode mixture slurry containing a positive electrode active material, a conductive agent, a binder, and a solvent such as N-methyl-2-pyrrolidone (NMP) to both sides of the positive electrode core, followed by drying and rolling.
[0022] Examples of positive electrode active materials include lithium-containing transition metal oxides containing transition metal elements such as Co, Mn, and Ni. While lithium-containing transition metal oxides are not particularly limited, they generally have the formula Li １＋ｘ MO ２ It is preferable that the composite oxide is represented by the formula (wherein -0.2 < x ≤ 0.2, and M includes at least one of Ni, Co, Mn, and Al).
[0023] Examples of the conductive agents mentioned above include acetylene black (AB), carbon black (CB) such as Ketjenblack, and carbon materials such as graphite. Examples of the binders mentioned above include fluororesins such as polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVdF), polyacrylonitrile (PAN), polyimide (PI), acrylic resins, and polyolefin resins. These resins may also be used in combination with carboxymethylcellulose (CMC) or its salts, polyethylene oxide (PEO), etc. These may be used individually or in combination of two or more types.
[0024] In the deployed state of the positive electrode 11, an uncoated portion of the positive electrode is formed as a core body exposed portion, where the surface of the metal constituting the positive electrode core is exposed in a part of the longitudinal direction. The positive electrode lead terminal 20 is connected to this uncoated portion of the positive electrode by bonding and extends from above the electrode body 14. The material of the positive electrode lead terminal 20 is not particularly limited. Preferably, the positive electrode lead terminal 20 is made of a metal mainly composed of aluminum.
[0025] The negative electrode 12 has a strip-shaped negative electrode core 40 and negative electrode mixture layers 42 formed on both sides of the negative electrode core 40. For the negative electrode core 40, for example, a metal foil such as copper, or a film with the metal arranged on its surface, can be used. The thickness of the negative electrode core 40 is, for example, 5 μm to 30 μm.
[0026] The negative electrode mixture layer 42 preferably contains a negative electrode active material and a binder. The negative electrode 12 is manufactured by, for example, applying a negative electrode mixture slurry containing a negative electrode active material, a binder, and water to both sides of the negative electrode core, and then drying and rolling it.
[0027] The negative electrode active material is not particularly limited as long as it can reversibly intercept and release lithium ions. For example, carbon materials such as natural graphite and artificial graphite, metals that alloy with lithium such as Si and Sn, or alloys and composite oxides containing these can be used. The binder contained in the negative electrode active material layer is, for example, the same resin as in the case of the positive electrode 11. When preparing the negative electrode mixture slurry with an aqueous solvent, styrene-butadiene rubber (SBR), CMC or its salts, polyacrylic acid or its salts, polyvinyl alcohol, etc. can be used. These may be used individually or in combination of two or more.
[0028] A porous sheet having ion permeability and insulating properties is used for the separator 13. Specific examples of porous sheets include microporous thin films, woven fabrics, and nonwoven fabrics. The material of the separator 13 is preferably an olefin resin such as polyethylene or polypropylene. The thickness of the separator 13 is, for example, 10 μm to 50 μm. The separator 13 is becoming thinner as batteries increase in capacity and power output. The separator 13 has a melting point of, for example, 130°C to 180°C.
[0029] Furthermore, in the deployed state of the negative electrode 12, the lower end, which is one end in the axial direction, has an uncoated negative electrode portion over its entire length where the negative electrode mixture layer 42 is not formed. The uncoated negative electrode portion is joined to the current collector plate 52 which is joined to the bottom of the container 15.
[0030] Then, with the second uncoated negative electrode portion (not shown), which is the exposed portion of the negative electrode core 40, positioned on the outermost surface of the negative electrode 12, which is the outermost surface of the electrode body 14, a tape (not shown) is attached to the outermost surface.
[0031] In the example shown in Figure 1, the battery case is composed of a container 15 and a sealing body 16. The sealing body 16 is formed by stacking an upper metal cap 27 and a lower metal filter plate 30 in the vertical direction. The cap 27 is hat-shaped with its center bulging upwards. As a result, the cap 27 has a short cylindrical projection 27a that protrudes upwards from the center. The projection 27a is formed when the upper end of a cylindrical rising wall 27b extending in the vertical direction is closed by a top plate 27c.
[0032] The container 15 has an annular groove 35 formed by recessing the upper end of the cylindrical portion radially inward along its entire circumference. The sealing body 16 is fitted inside the container 15 through the opening at the upper end of the cylindrical portion 15a via a gasket 28, and while locked to the upper surface of the groove 35, the upper end of the cylindrical portion 15a is crimped radially inward. As a result, the cap 27 of the sealing body 16 is positioned above the filter plate 30, and together with the filter plate 30, its outer peripheral end is crimped and fixed to the inside of the opening of the container 15 via the outer peripheral gasket 28, sealing the opening of the container 15. The outer peripheral end of the filter plate 30 surrounds the flange of the outer peripheral end of the cap 27 from below, is folded back along the upper surface of the flange, and is integrated with the cap 27.
[0033] An insulating plate 18 is provided above the electrode body 14. The positive electrode lead terminal 20 extends through a through hole in the insulating plate 18 towards the sealing body 16 and is welded at a weld joint 100 to the lower surface of the filter plate 30, which is positioned above the electrode body 14 inside the container 15. In the cylindrical battery 10, the cap 27, which is electrically connected to the filter plate 30, becomes the positive electrode terminal.
[0034] Furthermore, a current collector plate 52 is positioned below the electrode body 14. The current collector plate 52 is, for example, made of metal and formed in a shape having arms extending radially from a central part, such as a cross shape. The unpainted negative electrode portion 41 formed at the lower end of the negative electrode 12 is pressed against the upper surface of the current collector plate 52 below the electrode body 14 and joined to it, while tilted radially inward. The current collector plate 52 is also joined to the bottom plate portion 15b of the container 15. As a result, the negative electrode 12 is electrically connected to the container 15, which serves as the negative electrode terminal, via the current collector plate 52. The current collector plate 52 may, for example, be welded only to the radially outer end portion 15b.
[0035] Furthermore, an exhaust structure 60 is formed on the bottom surface of the container 15. The exhaust structure 60 is formed by an annular or C-shaped groove 61 formed on the bottom surface of the container 15. This groove 61 forms an annular or C-shaped thin-walled portion 62 surrounding the center of the bottom plate portion 15b of the container 15. If the pressure inside the container 15 rises to a predetermined value due to an abnormality in the cylindrical battery 10, the thin-walled portion 62 ruptures, and the high-temperature gas inside is discharged from the bottom of the container 15. The exhaust structure 60 is not limited to this configuration; any configuration that can exhaust the gas inside the container 15 when the pressure inside rises is acceptable.
[0036] Furthermore, a space 36 is formed between the portion of the cap 27 including the inner surface of the protrusion 27a and the upper surface of the filter plate 30. In addition, an annular or other thin-walled portion 37 is formed on the filter plate 30 at a position opposite to the space 36.
[0037] As shown in Figure 3, the thin-walled portion 37 is formed by an annular groove 38 provided on the upper surface of the filter plate 30. In this example, the thin-walled portion 37 and a part of the groove 38 are provided in a position that overlaps with the inner circumferential surface of the rising wall 27b that constitutes the protrusion 27a of the cap 27 when viewed in the axial direction of the cylindrical battery 10. The thin-walled portion 37 and the groove 38 are arranged on a circle centered on the central axis of the cylindrical battery 10. The inner circumferential surface of the rising wall 27b is also arranged on a circle centered on the central axis of the cylindrical battery 10.
[0038] Furthermore, the upper surface of the filter plate 30 that faces the space 36 provided inside the protrusion 27a of the cap 27 has a planar region 30a that is perpendicular to the vertical direction. As a result, as shown in Figure 4 described later, when the filter plate 30 breaks at the thin portion 37, and the plate portion 30c of the filter plate 30 on the inner circumference side of the thin portion 37 protrudes inward from the protrusion 27a and is pressed against the lower surface of the top plate 27c of the protrusion 27a, the volume of the space inside the cylindrical battery 10 that communicates with the electrode body 14 can be further increased.
[0039] The welded portion 100 between the filter plate 30 and the positive lead terminal 20 is located radially inward from the thin-walled portion 37 of the filter plate 30. In other words, the thin-walled portion 37 is located on the outer circumference side of the welded portion 100 of the positive lead terminal 20 of the filter plate 30.
[0040] Furthermore, an insulating layer is provided in the portion between the inner surface of the cap 27 and the upper surface of the filter plate 30, in contact with the space 36. Specifically, insulating layers 80 and 81 are formed on both the inner surface of the protrusion 27a of the cap 27, the top surface 27d which is the lower surface of the top plate 27c, and the side surface of the rising wall 27b connected to the top surface 27d. In Figures 1 and 3, the insulating layers 80 and 81 are shown by thick black lines. The insulating layers 80 and 81 are, for example, resin coatings. For example, polyvinyl chloride resin, nylon-based, polyethylene-based, polyethylene terephthalate-based resins, etc., can be used as the resin constituting the resin coating.
[0041] The insulating layers 80 and 81 are configured to have a thickness such that burrs generated on the plate portion 30c that has broken and protruded from the filter plate 30 do not penetrate the filter plate 30 after the filter plate 30 breaks. For example, the insulating layers 80 and 81 have a thickness that is 1 / 30 or more and 1 / 10 or less of the thickness of the filter plate 30.
[0042] It is preferable that the insulating layer 81 provided on the side surface of the rising wall 27b has a vertical range H1 (FIG. 3) that is longer than or equal to the thickness T of the portion of the filter plate 30 that contacts the space 36. The reason for this is that when the outer peripheral surface of the protruding plate portion 30c contacts the insulating layer 81 on the side surface of the rising wall 27b, the outer peripheral surface of the plate portion 30c can be more reliably brought into contact with the insulating layer 81, and the electrical connection between the plate portion 30c and the cap 27 can be more reliably blocked.
[0043] Also, the insulating layer 81 provided on the side surface of the rising wall 27b is preferably provided over the entire circumference of the side surface of the rising wall 27b. The reason for this is to more reliably bring the plate portion 30c into contact with the insulating layer 81 regardless of the circumferential position on the side surface of the rising wall 27b towards which the protruding plate portion 30c faces.
[0044] An insulating layer 90 is also provided on the upper surface of the filter plate 30, on the upper surface of the radially inner portion from the thin portion, which is the portion in contact with the space 36. The configuration and thickness of the insulating layer 90 are the same as those of the insulating layers 80 and 81.
[0045] Also, the heat resistance temperature of each of the insulating layers 80, 81, and 90 is preferably 150°C or higher. The reason for this is to ensure that the functions of the insulating layers 80, 81, and 90 can be maintained even if the interior becomes high temperature during abnormal operation of the battery.
[0046] According to the above cylindrical battery 10, in the configuration where the exhaust structure 60 is provided on the bottom surface of the container 15, when the internal pressure of the battery rises, as shown in FIG. 4, the filter plate 30 is broken at the thin-walled portion 37, so that the volume of the space communicating with the electrode body 14 in the battery increases. For example, in the example of FIG. 4, among the filter plates 30, the plate portion 30c radially inside the thin-walled portion 37 protrudes toward the inside of the protrusion 27a of the cap 27, and the upper surface of the plate portion 30c is pressed against the lower surface of the top plate 27c of the protrusion 27a. Thereby, since the escape space for the gas generated in the battery can be expanded, it is possible to prevent an excessively high pressure from acting on the inner surface of the cap 27 of the sealing body 16, and it is possible to suppress the exhaust of the high-temperature gas from the upper side, which is the arrangement side of the sealing body 16, due to the protrusion of the sealing body 16. Therefore, it is possible to suppress the unintentional heat dissipation due to the increase in the internal pressure of the battery. Accordingly, the heat dissipation performance can be improved, and the safety in a test that is likely to cause a short circuit under severe conditions simulating a harsh environment can be enhanced. <##
[0047] Further, in the cylindrical battery 10, as shown in FIG. 4, when the internal pressure of the battery rises, the filter plate 30 is broken at the annular thin-walled portion 37, and when the plate portion 30c in the radially inner part from the thin-walled portion 37 protrudes toward the inside of the cap 27, the positive electrode lead terminal 20 may remain welded to the filter plate 30. Even in this case, according to the cylindrical battery 10, since the insulating layers 80, 81, 90 are provided between the inner surface of the cap 27 and the upper surface of the filter plate 30, as shown in FIG. 4, the insulating layers 80, 81, 90 are interposed between the inner surface of the cap 27 and the plate portion 30c. Thereby, the electrical connection between the cap 27 and the positive electrode lead terminal 20 is interrupted. Therefore, even if the welded portion 100 between the positive electrode lead terminal 20 and the filter plate 30 does not come off, the current can be interrupted by the breakage of the sealing body 16.
[0048] Furthermore, in this example, a portion of the thin-walled portion 37 and the groove 38 are positioned so as to overlap with the inner circumferential surface of the rising wall 27b that constitutes the protrusion 27a of the cap 27 when viewed in the axial direction of the cylindrical battery 10. This allows for a larger opening area of the filter plate 30 when the thin-walled portion 37 breaks, thereby increasing the cross-sectional area of the exhaust passage to the inside of the protrusion 27a when the internal pressure rises, and improving exhaust performance. In addition, a larger opening area when the filter plate 30 breaks allows for a higher vent pressure, which is the gas pressure required to form that opening.
[0049] Furthermore, in this example, the thin-walled portion 37 of the filter plate 30 is formed by a groove 38 provided on the upper surface of the filter plate 30. As a result, there is no need to form a groove for the thin-walled portion on the lower surface of the filter plate 30, which improves the degree of freedom in the welding position of the positive lead terminal 20.
[0050] Furthermore, the cap 27 includes a projection 27a having a cylindrical rising wall 27b extending along the vertical direction, and the upper surface of the filter plate 30 facing the space within the projection 27a has a flat region 30a. This makes it easier to expand the volume inside the battery when the internal pressure rises, unlike the cap configuration described in Patent Document 1, which has a cylindrical portion that narrows towards the upper end.
[0051] Furthermore, in this example, the upper surface of the outer peripheral plate portion 30b (Figure 3), which is the portion of the filter plate 30 radially outside the thin-walled portion 37 and faces the lower surface of the flange of the cap 27, and the planar region 30a, which is the upper surface of the portion radially inside the thin-walled portion 37, are located on the same plane. This makes it possible to realize a thin structure with a small height for the sealing body 16, and thus increase the battery capacity when the height of the battery is the same.
[0052] In this embodiment, the groove formed in the filter plate 30 may be formed on the lower surface of the filter plate 30. Also, the insulating layer may be formed only on the inner surface of the protrusion 27a of the cap 27, on the top surface 27d which is the lower surface of the top plate 27c, and on the side surface of the rising wall 27b connected to the top surface 27d. Furthermore, one of the insulating layers 80, 81 on the cap 27 side and the insulating layer 90 on the filter plate 30 side may be omitted.
[0053] Figure 5 is a diagram of a comparative example cylindrical battery 10a, corresponding to Figure 4. As shown in Figure 5(a), the comparative example cylindrical battery 10a does not have an insulating layer on either the inner surface of the cap 27 or the upper surface of the filter plate, unlike the cylindrical battery 10 of the embodiment. In such a comparative example, as shown in Figure 4, the internal pressure of the battery increases, and high gas pressure is applied to the lower surface of the filter, causing the filter plate to break at the thin-walled portion, and the plate portion 30c radially inward from the thin-walled portion of the filter plate may be pressed against the inner surface of the cap 27. In this case, if the positive electrode lead terminal 20 remains welded to the filter plate 30, the filter plate 30 will come into direct contact with the lower surface of the top plate 27c of the cap 27 or the side surface of the rising wall 27b without an insulating layer in between, and the electrical connection between the positive electrode lead terminal 20 and the cap 27 cannot be interrupted. According to the above embodiment, such problems can be prevented.
[0054] In this example, the positive lead terminal 20 is welded to the filter plate 30, the cap 27 is the positive terminal, and the container 15 is the negative terminal. However, it is also possible to configure it so that the negative lead terminal is welded to the filter plate, the cap is the negative terminal, and the container is the positive terminal.
[0055] The present disclosure will be further described by the following embodiments. Configuration 1: A cylindrical battery comprising: an electrode body in which a strip-shaped positive electrode and a strip-shaped negative electrode are wound with a separator between them; a bottomed cylindrical container housing the electrode body; lead terminals connected to the electrode body and extending upward; a filter plate to which the lead terminals are welded and positioned above the electrode body in the container; and a cap positioned above the filter plate, with its outer peripheral end crimped to the opening of the container via a gasket together with the filter plate to seal the opening, wherein the bottom surface of the container has an exhaust structure; a space is formed between the cap and the filter plate; an annular thin-walled portion is formed on the filter plate at a position opposite to the space; the thin-walled portion is located on the outer peripheral side of the welded portion of the lead terminals on the filter plate; and an insulating layer is provided between the inner surface of the cap and the upper surface of the filter plate, in contact with the space. Configuration 2: The cylindrical battery according to Configuration 1, wherein the thin-walled portion is provided in a position that overlaps axially with the inner circumferential surface of the rising wall constituting the upwardly projecting projection of the cap. Configuration 3: The cylindrical battery according to Configuration 1 or Configuration 2, wherein the cap has an upwardly projecting projection, and the upper surface of the filter plate facing the space has a planar region perpendicular to the vertical direction. Configuration 4: The cylindrical battery according to any one of Configurations 1 to 3, wherein the thin-walled portion is formed by a groove provided on the upper surface of the filter plate. Configuration 5: The cylindrical battery according to any one of Configurations 1 to 4, wherein the cap has an upwardly projecting projection, and the insulating layer is formed on the inner surface of the projection, at least one of the inner top surface and the side surface connected to the top surface. Configuration 6: The cylindrical battery according to any one of Configurations 1 to 5, wherein the insulating layer has a thickness of 1 / 30 to 1 / 10 of the thickness of the filter plate. Configuration 7: The cylindrical battery according to any one of Configurations 1 to 6, wherein the heat resistance temperature of the insulating layer is 150°C or higher.
[0056] 10, 10a Cylindrical battery, 11 Positive electrode, 12 Negative electrode, 13 Separator, 14 Electrode body, 15 Container, 16, 16a Sealing body, 18 Insulating plate, 20 Positive electrode lead terminal, 27 Cap, 28 Gasket, 30 Filter plate, 30a Planar area, 35 Grooved section, 36 Space, 37 Thin-walled section, 38 Groove, 40 Negative electrode core, 41 Negative electrode unpainted section, 52 Current collector plate, 60 Exhaust structure, 61 Grooved section, 70 Filter plate, 80, 81, 90 Insulating layer, 100 Welded section.
Claims
1. A cylindrical battery comprising: an electrode body in which a strip-shaped positive electrode and a strip-shaped negative electrode are wound with a separator in between; a bottomed cylindrical container housing the electrode body; lead terminals connected to the electrode body and extending upward; a filter plate to which the lead terminals are welded and positioned above the electrode body within the container; and a cap positioned above the filter plate, with its outer peripheral end crimped to the opening of the container via a gasket together with the filter plate to seal the opening, wherein the bottom surface of the container has an exhaust structure; a space is formed between the cap and the filter plate; an annular thin-walled portion is formed on the filter plate at a position opposite to the space; the thin-walled portion is located on the outer peripheral side of the welded portion of the lead terminals on the filter plate; and an insulating layer is provided between the inner surface of the cap and the upper surface of the filter plate, in contact with the space.
2. The cylindrical battery according to claim 1, wherein the thin-walled portion is provided in a position that overlaps with the inner circumferential surface of the rising wall constituting the upwardly projecting portion of the cap when viewed in the axial direction.
3. The cylindrical battery according to claim 1, wherein the cap has a projection that protrudes upward, and the upper surface of the filter plate facing the space has a planar region perpendicular to the vertical direction.
4. The cylindrical battery according to claim 1, wherein the thin-walled portion is formed by a groove provided on the upper surface of the filter plate.
5. The cylindrical battery according to claim 1, wherein the cap has a projection that protrudes upward, and the insulating layer is formed on the inner surface of the projection, on at least one of the inner top surface and the side surface connected to the top surface.
6. The cylindrical battery according to claim 1, wherein the insulating layer has a thickness of 1 / 30 to 1 / 10 of the thickness of the filter plate.
7. The cylindrical battery according to claim 1, wherein the heat resistance temperature of the insulating layer is 150°C or higher.