Battery

Abstract

The disclosed battery is provided with a case, an electrode group, a sealing unit having a conductive cover, a terminal plate (60) joined to the opening edge of the case, and an insulating plate (70) that electrically insulates the conductive cover from the terminal plate (60). The housing and the terminal plate (60) are electrically connected to the first electrode, and the conductive cover is electrically connected to the second electrode. The terminal plate (60) has a first connection region to which the first external terminal (101) is connected, and the conductive cover has a second connection region to which the second external terminal is connected. The terminal plate (60) has a fracture-scheduled portion (64) between a joining portion (63) joined to the opening edge portion of the housing and the first connection region. When the internal pressure of the housing exceeds a predetermined value, the predetermined fracture portion (64) fractures, and the outer peripheral side fracture portion (65) and the inner peripheral side fracture portion (66) are separated in the axial direction of the housing. As a result, it is possible to provide a battery having a current blocking function.

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 body that seals the opening of the housing. The housing is electrically connected to the first electrode, and the sealing body is electrically connected to the second electrode.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: International Publication No. 2017 / 098690 Summary of the Invention

[0006] Problems to be Solved by the Invention

[0007] A battery sometimes experiences an internal short circuit due to an abnormality (for example, abnormal heat generation, etc.). An internal short circuit of a battery becomes particularly problematic when the battery is assembled into a battery pack. Therefore, a battery having a current interruption function for blocking an internal short circuit during an abnormality, that is, a function of blocking a current path between one terminal (for example, a housing) and the other terminal (for example, a sealing body), is desired. In such a situation, one of the objects of the present disclosure is to provide a battery having a current interruption function.

[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; a sealing unit having a conductive lid that seals the opening; a terminal plate that engages with an opening edge portion of the housing and extends radially inward of the housing; and an insulating plate that electrically insulates the conductive lid from the terminal plate. The housing and the terminal plate are electrically connected to the first electrode, the conductive lid is electrically connected to the second electrode. The terminal plate has a first connection area configured to connect to a first external terminal, the conductive lid has a second connection area configured to connect to a second external terminal. The terminal plate has a fracture predetermined portion provided between a joint portion that engages with the opening edge portion of the housing and the first connection area. The fracture predetermined portion is configured to fracture when the internal pressure of the housing exceeds a predetermined value, and the outer peripheral side fracture portion and the inner peripheral side fracture portion are separated in the axial direction of the housing.

[0010] Advantages of the Invention

[0011] According to the present disclosure, a battery having a current interruption function can be obtained.

[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 the present application, can be better understood from the following detailed description with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0015] Figure 3 FIG. is a conceptual diagram for explaining the current interruption 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 may be a primary battery such as a lithium primary battery, or may be 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 a power storage device (for example, a lithium-ion capacitor) 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 case, an electrode group, a sealing unit, a terminal plate, and an insulating plate. 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 case is formed in a bottomed cylindrical shape having an opening at one end. The case may be a bottomed cylindrical shape or a bottomed polygonal cylindrical shape. The case may 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 case and has a first electrode and a second electrode. The electrode group may 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 may 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 with micropores, a woven fabric, a non-woven fabric, and the like.

[0024] The sealing unit has a conductive lid that seals the opening of the housing. The conductive lid may be exposed to the outside of the housing. The conductive lid may be made of metal. The conductive lid may be, for example, in the shape of a circular plate or a polygonal plate. The sealing unit may further have: a current collecting plate disposed on the side of the electrode group closer to the conductive lid and joined to the conductive lid; and a gasket interposed between the conductive lid and the current collecting plate and the opening of the housing. The current collecting plate may be made of metal. The gasket may be made of an insulating resin (for example, polypropylene).

[0025] The terminal plate is joined to the opening edge of the housing and extends radially inward of the housing. The terminal plate may be exposed to the outside of the housing. The terminal plate may be made of metal. The terminal plate may be, for example, in the shape of a circular ring or a polygonal ring. The terminal plate may be joined to the opening edge of the housing by welding.

[0026] The insulating plate electrically insulates the conductive lid from the terminal plate. The insulating plate may be disposed between the conductive lid and the terminal plate. The insulating plate may be, for example, in the shape of a circular ring or a polygonal ring. The insulating plate may be made of an insulating resin having a melting point higher than that of the gasket.

[0027] The above-described housing and the above-described terminal plate are electrically connected to the first electrode of the electrode group. Thus, the housing and the terminal plate function as an external terminal on one side of the battery.

[0028] The above-described conductive lid is electrically connected to the second electrode of the electrode group. Thus, the conductive lid functions as an external terminal on the other side of the battery.

[0029] The terminal board has a first connection area configured for connecting a first external terminal (e.g., a first bus bar). The first connection area may be an area that does not overlap with the gasket in the axial direction of the housing. The first external terminal may be connected to the terminal board by welding.

[0030] The conductive cover has a second connection area configured for connecting a second external terminal (e.g., a second bus bar). The polarity of the second external terminal may be different from the polarity of the first external terminal. The second connection area may be the central area of the conductive cover. The second external terminal may be connected to the conductive cover by welding.

[0031] Thus, in the battery of the present disclosure, the terminal board connecting the first external terminal, the housing connected to the terminal board, and the first electrode electrically connected to the terminal board and the housing have one polarity (e.g., negative polarity), and the conductive cover connecting the second external terminal and the second electrode electrically connected to the conductive cover have the other polarity (e.g., positive polarity). In this battery, in the case of an internal short circuit where the housing and the conductive cover are electrically connected, for example, it is possible that the first external terminal and the second external terminal are electrically short-circuited.

[0032] In response to this, the terminal board of the present disclosure has a fracture predetermined portion provided between the joint portion joined to the opening edge portion of the housing and the first connection area. The fracture predetermined portion is configured to fracture when the internal pressure of the housing exceeds a predetermined value, and the outer peripheral side fracture portion and the inner peripheral side fracture portion are separated in the axial direction of the housing. When such a fracture occurs, the first connection area (including in the inner peripheral side fracture portion) connecting the first external terminal and the housing electrically connected to the terminal board at this joint portion (including in the outer peripheral side fracture portion) are electrically insulated from each other. The latter housing is electrically connected to the conductive cover connecting the second external terminal due to the above internal short circuit, but due to such electrical insulation, the first external terminal and the second external terminal are electrically insulated from each other. That is, by the fracture of the fracture predetermined portion of the present disclosure, the current path between the first external terminal and the second external terminal can be interrupted.

[0033] The fracture predetermined portion may be a first thin wall portion formed on the terminal board. The first thin wall portion may be the thinnest portion of the terminal board. The first thin wall portion may be formed by providing a groove or a notch in the terminal board. Such a first thin wall portion is likely to fracture due to stress concentration when an external force is applied to the terminal board. Thereby, the reliability of the current interruption function of the battery of the present disclosure can be improved.

[0034] The terminal board may have a transition portion where the thickness in the radial direction of the housing changes from a first thickness to a second thickness. The first thin-walled portion may be disposed at or near the transition portion. In such a transition portion, stress concentration occurs when an external force is applied to the terminal board. By disposing the first thin-walled portion at or near the transition portion where stress concentration occurs, the first thin-walled portion can be more easily broken. The first thickness may be greater than the thickness of the first thin-walled portion and less than the second thickness. In addition, disposing the first thin-walled portion at the transition portion means that the thinnest portion of the first thin-walled portion overlaps with the transition portion in the axial direction of the housing. On the other hand, disposing the first thin-walled portion near the transition portion means that the thinnest portion of the first thin-walled portion and the transition portion are included within a range of more than 0 mm and 0.5 mm or less in the radial direction of the housing.

[0035] The first thin-walled portion may be formed over the entire circumference of the terminal board in the circumferential direction of the housing. The thickness of the first thin-walled portion may be the same over the entire circumference or may be different locally. In addition, the first thin-walled portion may also be formed intermittently in multiple locations on the terminal board in the circumferential direction of the housing.

[0036] The insulating plate may be made of a thermal expansion material (e.g., polyphenylene sulfide, copolymer of tetrafluoroethylene and perfluoroalkoxyethylene, etc.) with a linear expansion coefficient of 2.0×10 -5 / K or more at 25°C. The insulating plate may be disposed to overlap with the region of the terminal board on the inner circumferential side with respect to the break predetermined portion in the axial direction of the housing. In this case, when the battery heats up, the insulating plate expands, and a part of the terminal board is lifted by the expanded insulating plate. By such lifting, the breakage of the break predetermined portion can be promoted.

[0037] The conductive cover may have a second thin-walled portion formed to be thinner than the surroundings. In the radial direction of the housing, the center of the innermost circumferential portion and the outermost circumferential portion of the second thin-walled portion may be located at a position closer to the outer circumference than the center of the innermost circumferential portion and the outermost circumferential portion of the insulating plate. In the radial direction of the housing, the center of the innermost circumferential portion and the outermost circumferential portion of the second thin-walled portion may be located at a position closer to the inner circumference than the break predetermined portion of the terminal board. Since stress concentration occurs in the second thin-walled portion when the internal pressure of the battery rises, deformation is likely to occur in the conductive cover. And a part of the terminal board is lifted by the conductive cover deformed at the second thin-walled portion. By such lifting, the breakage of the break predetermined portion can be promoted.

[0038] As described above, according to the present disclosure, by providing a break predetermined portion on the terminal board, a battery having a current interruption function can be provided. Moreover, according to the present disclosure, in a battery pack including a plurality of such batteries, a reduction in output when an internal short circuit occurs in a part of the batteries can be suppressed.

[0039] Hereinafter, an example of the battery of the present disclosure will be specifically described with reference to the accompanying drawings. The constituent elements of the battery in the example described below can be applied to the above-described constituent elements. The constituent elements of the battery in the example described below can be changed based on the above description. In addition, the matters described below can be applied to the above-described embodiments. Constituent elements that are not essential for the battery of the present disclosure can 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 quantities of actual components.

[0040] The battery 10 of the present embodiment is configured as a lithium-ion secondary battery, but is not limited thereto. As Figure 1 shown, the battery 10 includes a housing 20, an electrode group 30, a sealing unit 50, a terminal plate 60, and an insulating plate 70.

[0041] The housing 20 is formed in a bottomed cylindrical shape with an opening at one end ( Figure 1 the upper end in ), and has a cylindrical side wall portion 21 and a circular plate-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 housing 20 of the present embodiment is made of a metal mainly composed of iron, but is not limited thereto.

[0042] The electrode group 30 is housed in the housing 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 housing 20, and the positive electrode is electrically connected to a current collector 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.

[0043] The sealing unit 50 seals the opening of the housing 20. The sealing unit 50 includes a conductive lid 51, a current collector plate 54, and a gasket 55. The conductive lid 51 is made of metal and is exposed to the outside of the housing 20. The current collector plate 54 is made of metal and is disposed at a position closer to the electrode group 30 side ( Figure 1 the lower side in ) than the conductive lid 51, and is joined to the conductive lid 51 by welding, for example. As described above, since the current collector plate 54 is electrically connected to the positive electrode of the electrode group 30, the conductive lid 51 joined to the current collector 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 collector plate 54 and the caulking portion 22 of the housing 20.

[0044] 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 1The position of the lower side). The first insulating plate 81 is interposed between the electrode group 30 and the positive lead 41 to prevent contact between the negative electrode of the electrode group 30 and the positive lead 41. The second insulating plate 82 is interposed between the housing 20 and the positive lead 41 to prevent contact between the housing 20 and the positive lead 41.

[0045] The terminal plate 60 is joined to the opening edge portion of the housing 20 by welding and extends radially inward of the housing 20. The terminal plate 60 is made of metal and is exposed to the outside of the housing 20. The terminal plate 60 is formed in a circular ring shape. As described above, since the housing 20 is electrically connected to the negative electrode of the electrode group 30, the housing 20 and the terminal plate 60 joined thereto function as an external negative terminal.

[0046] The insulating plate 70 is disposed between the conductive cover 51 and the terminal plate 60 to electrically insulate the two. The insulating plate 70 is formed in a substantially circular ring shape. The insulating plate 70 is made of an insulating resin having a melting point higher than that of the gasket 55. In addition, the insulating plate 70 is made of a thermal expansion material having a linear expansion coefficient of 2.0×10 -5 / K or more at 25°C. The end portion on the outer peripheral side of the insulating plate 70 contacts the gasket 55, but is not limited thereto.

[0047] As Figure 1 and Figure 2 shown, the above-mentioned terminal plate 60 has a first connection region 61 configured to connect the first external terminal 101 (for example, the first bus bar). The thickness of the first connection region 61 ( Figure 2 the length in the vertical direction in) can be, for example, 0.5 mm or more and 0.6 mm or less. The terminal plate 60 has a transition portion 62 in which the thickness changes from a first thickness (for example, about 0.3 mm) to a second thickness (for example, about 0.4 mm) in the radial direction of the housing 20. In the transition portion 62 of the present embodiment, the thickness of the terminal plate 60 changes stepwise, but is not limited thereto.

[0048] The above-mentioned conductive cover 51 has a second connection region 52 configured to connect the second external terminal 102 (for example, the second bus bar having a polarity different from that of the first bus bar). The second connection region 52 can be, for example, the region of the conductive cover 51 that is exposed from the opening of the insulating plate 70. The conductive cover 51 has a second thin-walled portion 53 formed to be thinner than the surroundings. In the radial direction of the housing 20, the center of the innermost peripheral portion and the outermost peripheral portion of the second thin-walled portion 53 (indicated by a single-dot chain line C1) is located at a position closer to the outer periphery than the center of the innermost peripheral portion and the outermost peripheral portion of the insulating plate 70 (indicated by a single-dot chain line C2).

[0049] The terminal board 60 has a first thin wall portion 64 disposed between a joint portion 63 joined to the opening edge portion of the housing 20 and a first connection region 61. The first thin wall portion 64 is disposed near the transition portion 62 (in this example, slightly on the outer peripheral side of the transition portion). The first thin wall portion 64 is disposed at a position on the outer periphery side of the outer peripheral side end portion of the insulating plate 70. The first thin wall portion 64 is disposed at a position on the outer periphery side of the outer peripheral side end portion of the second thin wall portion 53. The first thin wall portion 64 is formed over the entire circumference of the terminal board 60 in the circumferential direction of the housing 20. As Figure 3 shown, the first thin wall portion 64 is configured to break when the internal pressure of the housing 20 exceeds a predetermined value, and the outer peripheral side fracture portion 65 and the inner peripheral side fracture portion 66 are separated in the axial direction of the housing 20. Here, when heat is generated in the housing 20 when the internal pressure of the housing 20 becomes high, the insulating plate 70 made of a thermally expandable material expands, and the portion of the terminal board 60 corresponding to the inner peripheral side fracture portion 66 is lifted, thereby promoting this fracture. In addition, in the same situation, the second thin wall portion 53 of the conductive cover 51 is greatly deformed toward the outside of the housing 20, and the portion of the terminal board 60 corresponding to the inner peripheral side fracture portion 66 is lifted, thereby promoting this fracture. The first thin wall portion 64 is an example of a fracture predetermined portion.

[0050] <Supplementary Note>

[0051] From the description of the above embodiments, the following technology is disclosed.

[0052] (Technology 1)

[0053] A battery includes:

[0054] a bottomed cylindrical housing having an opening at one end;

[0055] an electrode group housed in the housing and having a first electrode and a second electrode;

[0056] a sealing unit having a conductive cover for sealing the opening;

[0057] a terminal board joined to the opening edge portion of the housing and extending radially inward of the housing; and

[0058] an insulating plate for electrically insulating the conductive cover from the terminal board,

[0059] the housing and the terminal board are electrically connected to the first electrode,

[0060] the conductive cover is electrically connected to the second electrode,

[0061] the terminal board has a first connection region configured to be connected to a first external terminal,

[0062] The conductive cover has a second connection area configured for connecting to a second external terminal.

[0063] The terminal board has a predetermined breaking portion provided between a joint portion joined to the opening edge portion of the housing and the first connection area.

[0064] The predetermined breaking portion is configured to break when the internal pressure of the housing exceeds a predetermined value, and the outer peripheral breaking portion and the inner peripheral breaking portion are separated in the axial direction of the housing.

[0065] (Technology 2)

[0066] The battery according to Technology 1

[0067] The predetermined breaking portion is a first thin wall portion formed on the terminal board.

[0068] (Technology 3)

[0069] The battery according to Technology 2

[0070] The terminal board has a transition portion where the thickness changes from a first thickness to a second thickness in the radial direction of the housing.

[0071] The first thin wall portion is disposed at or near the transition portion.

[0072] (Technology 4)

[0073] The battery according to Technology 2 or 3

[0074] The first thin wall portion is formed on the terminal board over the entire circumference in the circumferential direction of the housing.

[0075] (Technology 5)

[0076] The battery according to any one of Technologies 1 to 4

[0077] The insulating plate is made of a thermal expansion material having a linear expansion coefficient of 2.0×10 -5 / K or more at 25°C.

[0078] (Technology 6)

[0079] The battery according to any one of Technologies 1 to 5

[0080] The conductive cover has a second thin wall portion formed to be thinner than the surroundings.

[0081] In the radial direction of the housing, the center of the innermost circumference and the outermost circumference of the second thin wall portion is located at a position closer to the outer circumference than the center of the innermost circumference and the outermost circumference of the insulating plate.

[0082] 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 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.

[0083] Industrial Applicability

[0084] This disclosure can be used for batteries.

[0085] Explanation of Reference Numerals

[0086] 10: Battery

[0087] 20: Housing

[0088] 21: Side Wall Portion

[0089] 22: Caulking Portion

[0090] 23: Bottom

[0091] 30: Electrode Group

[0092] 41: Positive Electrode Lead

[0093] 50: Sealing Unit

[0094] 51: Conductive Cover

[0095] 52: Second Connection Region

[0096] 53: Second Thin Wall Portion

[0097] 54: Current Collector Plate

[0098] 55: Gasket

[0099] 60: Terminal Plate

[0100] 61: First Connection Region

[0101] 62: Transition Portion

[0102] 63: Joint Portion

[0103] 64: First Thin Wall Portion (Predetermined Fracture Portion)

[0104] 65: Outer Peripheral Side Fracture Portion

[0105] 66: Inner Peripheral Side Fracture Portion

[0106] 70: Insulating Plate

[0107] 81: First Insulating Plate

[0108] 82: Second Insulating Plate

[0109] 101: First external terminal

[0110] 102: Second external terminal

Claims

1. A battery, comprising: a bottomed cylindrical case having an opening at one end; an electrode group housed in the case and having a first electrode and a second electrode; a sealing unit having a conductive lid for sealing the opening; a terminal plate joined to the opening edge of the case and extending radially inward of the case; and an insulating plate for electrically insulating the conductive lid from the terminal plate, wherein the case and the terminal plate are electrically connected to the first electrode, the conductive lid is electrically connected to the second electrode, the terminal plate has a first connection area configured for connection of a first external terminal, the conductive lid has a second connection area configured for connection of a second external terminal, the terminal plate has a fracture predetermined portion provided between a joining portion joined to the opening edge of the case and the first connection area, the fracture predetermined portion is configured to fracture when the internal pressure of the case exceeds a predetermined value, and the outer peripheral fracture portion and the inner peripheral fracture portion are separated in the axial direction of the case.

2. The battery according to claim 1, wherein the fracture predetermined portion is a first thin wall portion formed in the terminal plate.

3. The battery according to claim 2, wherein the terminal plate has a transition portion where the thickness changes from a first thickness to a second thickness in the radial direction of the case, and the first thin wall portion is disposed at or near the transition portion.

4. The battery according to claim 2 or 3, wherein the first thin wall portion is formed in the terminal plate over the entire circumference in the circumferential direction of the case.

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

6. The battery according to any one of claims 1 to 3, wherein the conductive lid has a second thin wall portion formed to be thinner than the surroundings, and in the radial direction of the case, the center of the innermost circumference and the outermost circumference of the second thin wall portion is located at a position more peripheral than the center of the innermost circumference and the outermost circumference of the insulating plate.

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