Battery

Abstract

The disclosed battery (10) is provided with: a case (20); an electrode group housed in the case (20) and having a first electrode and a second electrode; and a sealing unit (50) that seals the opening of the housing (20). The case (20) has a caulking section (22) for fixing the sealing unit (50), and is electrically connected to the first electrode. The sealing unit (50) has: a collector plate (54) electrically connected to the second electrode; a conductive cover (51) that is disposed further to the outside in the axial direction than the collector plate (54), and that is joined to the collector plate (54) at a first joining section (J); an insulating gasket (55) interposed between the clinching section (22) and the collector plate (54) and the conductive cover (51); and an insulating member (56) including a first insulating portion (56a) disposed between the peripheral edge portion of the collector plate (54) and the peripheral edge portion of the conductive cover (51). The first insulating portion (56a) is disposed at a position closer to the outer periphery than the first joining portion (J). As a result, internal short-circuits during combustion can be suppressed.

Description

Technical Field

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

[0002] Conventionally, a battery that can be repeatedly used by charging and discharging has been known (for example, Patent Document 1). The battery of Patent Document 1 includes: a bottomed cylindrical housing having an opening at one end; an electrode group housed in the housing and having a first electrode and a second electrode; and a sealing unit that seals the opening of the housing. The sealing unit includes: a sealing body formed by laminating a filter, a lower valve body, an insulator, an upper valve body, and a lid in this order from the electrode group side; and a gasket provided between the housing and the sealing body.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2019-153388 Summary of the Invention

[0006] Problems to be Solved by the Invention

[0007] A battery sometimes catches fire when an abnormality occurs. When a fire occurs, the gasket may melt due to the heat, and the components of the sealing body may come into contact with the housing and become electrically conductive. Such electrical conduction or internal short circuit becomes particularly problematic in a battery pack having a plurality of batteries. This is because, for a battery that has caught fire, a large current flows in from other batteries, and the output of the battery pack decreases. In such a situation, one of the objects of the present disclosure is to suppress an internal short circuit during combustion.

[0008] Means for Solving the Problems

[0009] One aspect of the present disclosure relates to a battery. The battery includes: a bottomed cylindrical housing having an opening at one end; an electrode group housed in the housing and having a first electrode and a second electrode; and a sealing unit that seals the opening. The housing has a caulking portion that fixes the sealing unit and is electrically connected to the first electrode. The sealing unit includes: a current collector plate electrically connected to the second electrode; a conductive lid disposed at a position axially outside the housing with respect to the current collector plate and joined to the current collector plate by a first joining portion; an insulating gasket interposed between the caulking portion and the current collector plate and the conductive lid; and an insulating member including a first insulating portion disposed between the peripheral edge of the current collector plate and the peripheral edge of the conductive lid, and the first insulating portion is disposed at a position outside the first joining portion in the outer circumference.

[0010] Advantages of the Invention

[0011] According to the present disclosure, internal short circuits during combustion can be suppressed.

[0012] The novel features of the present invention are described in the appended claims. The present invention relates to both the constitution and the content, and together with other objects and features of this application, can be better understood from the following detailed description with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a cross-sectional view schematically showing an example of the battery of the present disclosure.

[0014] Figure 2 shows Figure 1 an enlarged cross-sectional view of the main part of the battery.

[0015] Figure 3 is a conceptual diagram for explaining the short-circuit suppression function of the battery of the present disclosure. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0016] Hereinafter, embodiments of the battery of the present disclosure will be described by way of example. However, the present disclosure is not limited to the examples described below. In the following description, specific numerical values and materials are sometimes exemplified, but other numerical values and materials can also be applied as long as the effects of the present disclosure can be obtained.

[0017] The battery of the present disclosure can be a primary battery such as a lithium primary battery, or a secondary battery such as an alkaline storage battery (nickel-metal hydride battery, nickel-cadmium battery, etc.), a lithium-ion secondary battery, or a lithium-metal secondary battery. In the present disclosure, the category of secondary batteries also includes electrical storage devices (for example, lithium-ion capacitors) in which at least one of the positive electrode and the negative electrode is an electrode that exhibits capacitance through a Faraday reaction.

[0018] The battery of the present disclosure includes a housing, an electrode group, and a sealing unit. In addition, the type of the battery is not particularly limited as described above, and hereinafter, the case of a lithium-ion secondary battery will be mainly described as an example.

[0019] The housing is formed in a bottomed cylindrical shape with an opening at one end. The housing can be a bottomed cylindrical shape or a bottomed polygonal cylindrical shape. The housing can be made of a conductor (for example, a metal mainly composed of iron, or a metal mainly composed of aluminum).

[0020] The electrode group is housed in the housing and has a first electrode and a second electrode. The electrode group can be a wound-type electrode group in which the first electrode and the second electrode are wound with a separator interposed therebetween. The outer shape of the electrode group can be, for example, a cylindrical shape or a prismatic shape. One of the first electrode and the second electrode is a positive electrode, and the other of the first electrode and the second electrode is a negative electrode.

[0021] The first electrode may have a first current collector in the form of a long-sized sheet and a first active material layer formed on the surface of the first current collector. When the first electrode is the negative electrode of a lithium-ion secondary battery, the first current collector may be made of a copper foil or a copper alloy foil. When the first electrode is the negative electrode of a lithium-ion secondary battery, the first active material layer may include a negative electrode active material (such as a carbonaceous material, a silicon-containing material, etc.), a conductive agent, a binder, and the like. In addition, the first active material layer may not be provided.

[0022] The second electrode may have a second current collector in the form of a long-sized sheet and a second active material layer formed on the surface of the second current collector. When the second electrode is the positive electrode of a lithium-ion secondary battery, the second current collector may be made of an aluminum foil or an aluminum alloy foil. When the second electrode is the positive electrode of a lithium-ion secondary battery, the second active material layer may include a positive electrode active material (for example, a lithium-containing transition metal oxide), a conductive agent, a binder, and the like.

[0023] The separator may be made of a porous sheet having ion permeability and insulation properties. Examples of the porous sheet include a thin film having micropores, a woven fabric, a non-woven fabric, and the like.

[0024] The above-mentioned housing has a caulking portion for fixing the sealing unit. The housing is electrically connected to the first electrode of the electrode group. Thus, the housing functions as an external terminal on one side of the battery.

[0025] The sealing unit seals the opening of the housing. The sealing unit has a current collecting plate, a conductive cover, an insulating gasket, and an insulating member. The current collecting plate is electrically connected to the second electrode of the electrode group. The conductive cover is disposed at a position axially outside the housing relative to the current collecting plate and is joined to the current collecting plate by a first joining portion. Thus, the conductive cover functions as an external terminal on the other side of the battery. The gasket is interposed between the caulking portion and the current collecting plate and the conductive cover. The gasket may be made of, for example, polypropylene. The insulating member includes a first insulating portion disposed between the peripheral portion of the current collecting plate and the peripheral portion of the conductive cover. The first insulating portion is disposed at a position outside the first joining portion in the outer periphery.

[0026] The first insulating part is preferably made of a material having a higher heat resistance than that of the gasket. For example, the first insulating part may contain a resin material having a melting point or a heat deflection temperature higher than that of the gasket as a main component, may include ceramics as a main component, or may be composed of a cured product of a thermosetting resin composition. The heat deflection temperature can be measured by performing the heat deflection temperature measurement according to the test method ASTM-D648 of the American Society for Testing and Materials. In addition, the main component may be a component of 50% by mass or more of the first insulating part, or may be a component of 70% by mass or more of the first insulating part. From the viewpoints of high airtightness and heat resistance, the insulating member including the first insulating part may be made of, for example, polyphenylene sulfide or a copolymer of tetrafluoroethylene and perfluoroalkoxyethylene.

[0027] Here, when the battery catches fire, it is possible that the gasket melts, and the conductive component (especially the current collector plate) of the sealing unit comes into contact with the caulking part of the housing, thereby causing an internal short circuit. However, the sealing unit of the present disclosure has an insulating member including the first insulating part at a position outside the gasket and more difficult to burn. Such a first insulating part is difficult to melt or burn even when the battery catches fire. By disposing the first insulating part between the peripheral part of the current collector plate and the peripheral part of the conductive cover, even if the current collector plate comes into contact with the caulking part of the housing, the state in which the conductive cover is insulated from the current collector plate and the housing can be maintained. In addition, when the battery catches fire, the first joint part between the current collector plate and the conductive cover can release its joint state by the combustion heat and / or by the thermal expansion of the first insulating part. Therefore, an internal short circuit during combustion can be suppressed.

[0028] The insulating member may further include a second insulating part that extends along the axial direction of the housing from the outer peripheral end of the first insulating part and is located between the conductive cover and the gasket. That is, the second insulating part is located radially outside the peripheral part of the conductive cover, and a part of the gasket exists radially outside the second insulating part. The second insulating part may contain a resin material having a melting point or a heat deflection temperature higher than that of the gasket as a main component, may contain ceramics as a main component, or may be composed of a cured product of a thermosetting resin composition. According to this configuration, even if the gasket radially outside the peripheral part of the conductive cover melts during combustion, contact between the peripheral part of the conductive cover and the caulking part of the housing can be suppressed by the second insulating part.

[0029] The insulating member may further include a third insulating portion that extends radially inward from the end of the second insulating portion and is located between the conductive cover and the gasket. That is, the third insulating portion is located axially outside the peripheral portion of the conductive cover, and a part of the gasket exists axially outside the third insulating portion. The third insulating portion may contain a resin material having a melting point or a heat deflection temperature higher than that of the gasket as a main component, may contain ceramics as a main component, or may be formed of a cured product of a thermosetting resin composition. According to this configuration, even if the gasket axially outside the peripheral portion of the conductive cover melts during combustion, the third insulating portion can suppress the contact between the peripheral portion of the conductive cover and the caulking portion of the housing.

[0030] The insulating member may be made of a thermal expansion material having a linear expansion coefficient of 2.0×10 -5 / K or more at 25°C. In this case, the first insulating portion expands significantly during battery combustion, and thus the joint state of the first joint portion is easily released. Therefore, even if the portion of the current collector plate corresponding to the first joint portion does not melt due to the combustion heat, it is easy to electrically insulate the current collector plate from the conductive cover.

[0031] Let the radial distance from the outer peripheral edge of the conductive cover to the first joint portion be D, and the radial distance from the outer peripheral edge of the conductive cover to the inner peripheral end of the first insulating portion may be 0.25D or more. According to this configuration, the inner peripheral end of the first insulating portion is located relatively close to the first joint portion. Therefore, due to the expansion of the first insulating portion during battery combustion, it is easy to separate the current collector plate and the conductive cover from each other at the first joint portion, and the joint state of the first joint portion is easily released. In addition, the radial distance from the outer peripheral edge of the conductive cover to the inner peripheral end of the first insulating portion may also be 0.4D or more, 0.5D or more, 0.6D or more, 0.7D or more, 0.8D or more, or 0.9D or more.

[0032] As described above, according to the present disclosure, by providing the insulating member at a position where the gasket is less likely to burn, an internal short circuit during combustion can be suppressed.

[0033] Hereinafter, an example of the battery of the present disclosure will be specifically described with reference to the drawings. The constituent elements of the battery in the example described below may be applied to the above-described constituent elements. The constituent elements of the battery in the example described below may be changed based on the above description. In addition, the matters described below may be applied to the above-described embodiments. Constituent elements that are not essential for the battery of the present disclosure may be omitted from the battery in the example described below. In addition, the drawings shown below are schematic diagrams and do not accurately reflect the shapes and numbers of actual members.

[0034] The battery 10 of the present embodiment is configured as a lithium ion secondary battery, but is not limited thereto. AsFigure 1 and Figure 2 As shown in and

[0035] , the battery 10 includes a case 20, an electrode group 30, and a sealing unit 50.

[0035] The case 20 is formed as a bottomed cylindrical shape having an opening at one end ( Figure 1 the upper end in this example), and has a cylindrical side wall portion 21 and a disc-shaped bottom portion 23. In a region near the opening in the side wall portion 21, a caulking portion 22 for fixing the sealing unit 50 is formed. The case 20 of the present embodiment is made of a metal mainly composed of iron, but is not limited thereto.

[0036] The electrode group 30 is housed in the case 20 and has a negative electrode and a positive electrode. The electrode group 30 is a wound type electrode group in which the negative electrode and the positive electrode are wound with a separator interposed therebetween. The outer shape of the electrode group 30 is cylindrical. The negative electrode is electrically connected to the bottom portion 23 of the case 20. Therefore, the case 20 functions as an external negative terminal. The positive electrode is electrically connected to a current collecting plate 54 (described later) of the sealing unit 50 via a positive electrode lead 41. The negative electrode is an example of the first electrode, and the positive electrode is an example of the second electrode.

[0037] The sealing unit 50 seals the opening of the case 20. The sealing unit 50 includes a conductive lid 51, a current collecting plate 54, and a gasket 55. The conductive lid 51 is made of metal and is disposed at a position axially outside the case 20 with respect to the current collecting plate 54. The conductive lid 51 is exposed to the outside of the case 20. The current collecting plate 54 is made of metal and is joined to the conductive lid 51 at a first joint portion J by welding, for example. As described above, since the current collecting plate 54 is electrically connected to the positive electrode of the electrode group 30, the conductive lid 51 joined to the current collecting plate 54 functions as an external positive terminal. The gasket 55 is made of an insulating resin and is interposed between the conductive lid 51 and the current collecting plate 54 and the caulking portion 22.

[0038] The sealing unit 50 further includes an insulating member 56 having a melting point or a heat deflection temperature higher than that of the gasket 55. The insulating member 56 is made of a thermal expansion material having a linear expansion coefficient of 2.0×10 -5 / K or more at 25°C, but is not limited thereto. For example, the insulating member 56 may contain ceramics as a main component. The insulating member 56 is disposed at a position more peripheral than the above-described first joint portion J, and includes a first insulating portion 56a, a second insulating portion 56b, and a third insulating portion 56c. The first insulating portion 56a is disposed between the peripheral edge portion of the current collecting plate 54 and the peripheral edge portion of the conductive lid 51. The second insulating portion 56b extends from the outer peripheral end portion of the first insulating portion 56a in the axial direction of the case 20 ( Figure 1 upward in this example), and is located between the conductive lid 51 and the gasket 55. The third insulating portion 56c extends from the end portion of the second insulating portion 56b ( Figure 1extends radially inwardly towards the upper end portion in) the housing 20 and is located between the conductive cover 51 and the gasket 55.

[0039] Let the radial distance from the outer peripheral edge of the conductive cover 51 to the first joint J be D, and the radial distance from the outer peripheral edge of the conductive cover 51 to the inner peripheral end portion of the first insulating portion 56a is 0.25D or more, preferably 0.5D or more, and more preferably 0.8D or more.

[0040] A first insulating plate 81 and a second insulating plate 82 are provided between the electrode group 30 and the sealing unit 50. The first insulating plate 81 is disposed closer to the electrode group 30 side than the second insulating plate 82 ( Figure 1 the lower side in). The first insulating plate 81 is interposed between the electrode group 30 and the positive electrode lead 41 to prevent contact between the negative electrode of the electrode group 30 and the positive electrode lead 41. The second insulating plate 82 is interposed between the housing 20 and the positive electrode lead 41 to prevent contact between the housing 20 and the positive electrode lead 41.

[0041] Figure 3 The states before and after combustion in the battery 10 of the present embodiment are shown respectively. As shown in this figure, when combustion occurs in the battery 10, it is possible that the gasket 55 melts and the peripheral portion of the current collector plate 54 contacts the housing 20. However, in the battery 10 of the present embodiment, since the insulating member 56 having a high melting point or heat deflection temperature is interposed between the peripheral portion of the current collector plate 54 and the peripheral portion of the conductive cover 51, electrical conduction between the housing 20 and the conductive cover 51 can be suppressed. In addition, the region near the inner circumference in the current collector plate 54 sometimes melts during combustion, but sometimes remains melted. In the latter case, it is possible that the housing 20 and the conductive cover 51 are electrically conducted via the first joint J. However, the insulating member 56 of the present embodiment expands greatly due to the heat during combustion. Therefore, the joint at the first joint J is released by this expansion. As described above, in the battery 10 of the present embodiment, an internal short circuit during combustion can be suppressed.

[0042] <Supplementary Note>

[0043] Through the description of the above embodiments, the following technology is disclosed.

[0044] (Technology 1)

[0045] A battery, comprising:

[0046] A bottomed cylindrical housing having an opening at one end;

[0047] An electrode group housed in the housing, having a first electrode and a second electrode; and

[0048] A sealing unit for sealing the opening,

[0049] The housing has a caulking portion for fixing the sealing unit and is electrically connected to the first electrode.

[0050] The sealing unit has:

[0051] A current collector plate electrically connected to the second electrode;

[0052] A conductive cover disposed at a position axially outside the housing relative to the current collector plate and joined to the current collector plate by a first joint portion;

[0053] An insulating gasket interposed between the caulking portion and the current collector plate and the conductive cover; and

[0054] An insulating member including a first insulating portion disposed between the peripheral portion of the current collector plate and the peripheral portion of the conductive cover,

[0055] The first insulating portion is disposed at a position more peripheral than the first joint portion.

[0056] (Technology 2)

[0057] The battery according to Technology 1,

[0058] The insulating member further includes a second insulating portion extending axially along the housing from the outer peripheral end of the first insulating portion and located between the conductive cover and the gasket.

[0059] (Technology 3)

[0060] The battery according to Technology 2,

[0061] The insulating member further includes a third insulating portion extending radially inward of the housing from the end of the second insulating portion and located between the conductive cover and the gasket.

[0062] (Technology 4)

[0063] The battery according to any one of Technologies 1 to 3,

[0064] The insulating member is made of a thermal expansion material having a linear expansion coefficient of 2.0×10 -5 / K or more at 25°C.

[0065] (Technology 5)

[0066] The battery according to Technology 4,

[0067] Let the radial distance from the outer peripheral edge of the conductive cover to the first joint portion be D, and the radial distance from the outer peripheral edge of the conductive cover to the inner peripheral end of the first insulating portion is 0.25D or more.

[0068] (Technology 6)

[0069] The battery according to any one of Technologies 1 to 5

[0070] The melting point or heat deflection temperature of the first insulating portion is higher than the melting point or heat deflection temperature of the gasket.

[0071] (Technology 7)

[0072] The battery according to any one of Technologies 1 to 6

[0073] The first insulating portion contains ceramics.

[0074] Although the present invention has been described with respect to the current preferred embodiments, such disclosure is not to be construed in a limiting sense. Various modifications and changes will no doubt be apparent to those skilled in the art belonging to the technical field of the present invention upon reading the above disclosure. Therefore, the appended claims should be construed to include all modifications and changes without departing from the true spirit and scope of the present invention.

[0075] Industrial applicability

[0076] This disclosure can be used for batteries.

[0077] Explanation of reference numerals

[0078] 10: Battery

[0079] 20: Case

[0080] 21: Side wall portion

[0081] 22: Caulking portion

[0082] 23: Bottom

[0083] 30: Electrode group

[0084] 41: Positive electrode lead

[0085] 50: Sealing unit

[0086] 51: Conductive cover

[0087] 54: Current collector plate

[0088] 55: Gasket

[0089] 56: Insulating member

[0090] 56a: First insulating portion

[0091] 56b: Second insulating portion

[0092] 56c: Third insulating portion

[0093] 81: First insulating plate

[0094] 82: Second insulating plate

[0095] J: First joint

Claims

1. A battery, comprising: A bottomed cylindrical housing having an opening at one end; An electrode group housed in the housing and having a first electrode and a second electrode; and A sealing unit for sealing the opening, The housing has a caulking portion for fixing the sealing unit and is electrically connected to the first electrode, The sealing unit has: A current collector plate electrically connected to the second electrode; A conductive cover disposed at a position axially outside the housing relative to the current collector plate and joined to the current collector plate by a first joint portion; An insulating gasket interposed between the caulking portion and the current collector plate and the conductive cover; And An insulating member including a first insulating portion disposed between the peripheral portion of the current collector plate and the peripheral portion of the conductive cover, The first insulating portion is disposed at a position outside the first joint portion in the outer circumference.

2. The battery according to claim 1, The insulating member further includes a second insulating portion extending axially along the housing from the outer peripheral end of the first insulating portion and located between the conductive cover and the gasket.

3. The battery according to claim 2, The insulating member further includes a third insulating portion extending radially inward of the housing from the end of the second insulating portion and located between the conductive cover and the gasket.

4. The battery according to any one of claims 1 to 3, The insulating member is made of a thermal expansion material having a linear expansion coefficient of 2.0×10 -5 / K or more at 25°C.

5. The battery according to claim 4, Let the radial distance from the outer peripheral edge of the conductive cover to the first joint portion be D, and the radial distance from the outer peripheral edge of the conductive cover to the inner peripheral end of the first insulating portion is 0.25D or more.

6. The battery according to any one of claims 1 to 3, The melting point or heat deflection temperature of the first insulating portion is higher than the melting point or heat deflection temperature of the gasket.

7. The battery according to any one of claims 1 to 3, The first insulating portion contains ceramics.

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