Battery

Abstract

Disclosed is a battery which is provided with: a case; an electrode group; a sealing unit which has a conductive cap; a terminal plate 60 which is bonded to the opening edge of the case; and an insulating plate 70 which electrically insulates the conductive cap and the terminal plate 60 from each other. The case and the terminal plate 60 are electrically connected to a first electrode, while the conductive cap is electrically connected to a second electrode. The terminal plate 60 has a first connection region to which a first external terminal 101 is connected, while the conductive cap has a second connection region to which a second external terminal is connected. The terminal plate 60 has an intended breaking part 64 between a bonding portion 63, at which the terminal plate is bonded to the opening edge of the case, and the first connection region. The intended breaking part 64 breaks if the internal pressure of the case exceeds a predetermined value, and an outer periphery-side broken part 65 and an inner periphery-side broken part 66 are separated from each other in the axial direction of the case. Consequently, the present invention is capable of providing a battery that has a current interrupting function.

Description

battery

[0001] The present disclosure relates to batteries.

[0002] Conventionally, batteries that can be repeatedly used by charging and discharging are known (for example, Patent Document 1). The battery in Patent Document 1 includes a cylindrical case with a bottom and an opening at one end, an electrode group housed in the case and including a first electrode and a second electrode, and a sealing member that seals the case opening. The case is electrically connected to the first electrode, and the sealing member is electrically connected to the second electrode.

[0003] International Publication No. 2017 / 098690

[0004] However, batteries may experience internal short circuits due to abnormalities (e.g., abnormal heat generation, etc.). Internal short circuits in batteries are particularly problematic when the battery is incorporated into a battery pack. Therefore, a battery having a current interruption function to prevent internal short circuits in the event of an abnormality, i.e., a function to interrupt the current path between one terminal (e.g., the case) and the other terminal (e.g., the sealing body), is desired. In this situation, one of the objects of the present disclosure is to provide a battery having a current interruption function.

[0005] One aspect of the present disclosure relates to a battery, the battery including: a cylindrical case with a bottom having an opening at one end; an electrode group housed in the case and having first and second electrodes; a sealing unit having a conductive cap and sealing the opening; a terminal plate joined to an edge of the case opening and extending radially inward of the case; and an insulating plate electrically insulating the conductive cap from the terminal plate, the case and the terminal plate being electrically connected to the first electrodes, the conductive cap being electrically connected to the second electrodes, the terminal plate having a first connection region configured to be connected to a first external terminal, the conductive cap having a second connection region configured to be connected to a second external terminal, the terminal plate having an intended rupture portion provided between a joint portion with the edge of the case opening and the first connection region, the intended rupture portion being configured to rupture when an internal pressure of the case exceeds a predetermined value, such that the outer circumferential rupture portion and the inner circumferential rupture portion are separated in the axial direction of the case.

[0006] According to the present disclosure, a battery having a current interrupt function can be obtained.

[0007] The novel features of the present invention are set forth in the appended claims, but the present invention, both in terms of structure and content, together with other objects and features of the present application, will be better understood from the following detailed description taken in conjunction with the drawings.

[0008] It is a cross-sectional view showing a schematic example of a battery according to the present disclosure. It is an enlarged cross-sectional view showing a main part of the battery of Figure 1. It is a conceptual diagram for explaining the current interrupt function of the battery according to the present disclosure.

[0009] An embodiment of a battery according to the present disclosure will be described below using examples. However, the present disclosure is not limited to the examples described below. In the following description, specific numerical values ​​and materials may be used as examples, but other numerical values ​​and materials may be used as long as the effects of the present disclosure are obtained.

[0010] The battery according to the present disclosure may 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 power storage devices (for example, lithium-ion capacitors) in which at least one of the positive electrode and negative electrode is an electrode that generates capacity through a Faraday reaction.

[0011] The battery according to the present disclosure includes a case, an electrode group, a sealing unit, a terminal plate, and an insulating plate. Although the type of battery is not particularly limited as described above, the following description will mainly focus on a lithium-ion secondary battery.

[0012] The case is formed in a bottomed tubular shape with an opening at one end. The case may be a bottomed cylindrical shape or a bottomed rectangular tubular shape. The case may be made of a conductor (e.g., a metal primarily containing iron or a metal primarily containing aluminum).

[0013] The electrode group is housed in a case and includes a first electrode and a second electrode. The electrode group may be a wound electrode group formed by winding the first electrode and the second electrode with a separator interposed therebetween. The electrode group may have, for example, a cylindrical or prismatic outer 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.

[0014] The first electrode may have a first current collector in the form of a long 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 copper foil or 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 or a silicon-containing material), a conductive agent, and a binder. The first active material layer may not be provided.

[0015] The second electrode may have a second current collector in the form of a long sheet and a second active material layer formed on the surface of the second current collector. When the second electrode is a positive electrode of a lithium-ion secondary battery, the second current collector may be made of aluminum foil or aluminum alloy foil. When the second electrode is a positive electrode of a lithium-ion secondary battery, the second active material layer may include a positive electrode active material (e.g., a lithium-containing transition metal oxide), a conductive agent, a binder, etc.

[0016] The separator may be made of a porous sheet having ion permeability and insulating properties, such as a thin film, woven fabric, or nonwoven fabric having micropores.

[0017] The sealing unit has a conductive cap and seals the opening of the case. The conductive cap may be exposed to the outside of the case. The conductive cap may be made of metal. The conductive cap may be, for example, disc-shaped or rectangular. The sealing unit may further have a current collector plate that is provided closer to the electrode group than the conductive cap and is joined to the conductive cap, and a gasket that is interposed between the conductive cap and the current collector plate and the opening of the case. The current collector plate may be made of metal. The gasket may be made of insulating resin (for example, polypropylene).

[0018] The terminal plate is joined to the opening edge of the case and extends radially inward of the case. The terminal plate may be exposed to the outside of the case. The terminal plate may be made of metal. The terminal plate may be, for example, in the shape of a circular ring or a square ring. The terminal plate may be joined to the opening edge of the case by welding.

[0019] The insulating plate electrically insulates the conductive cap from the terminal plate. The insulating plate may be disposed between the conductive cap and the terminal plate. The insulating plate may be, for example, in the shape of a circular ring or a square ring. The insulating plate may be made of an insulating resin having a melting point higher than that of the gasket.

[0020] The case and the terminal plate are electrically connected to the first electrode of the electrode group, and thus function as one external terminal of the battery.

[0021] The conductive cap is electrically connected to the second electrode of the electrode group, and therefore functions as the other external terminal of the battery.

[0022] The terminal plate has a first connection region configured to be connected to a first external terminal (e.g., a first bus bar). The first connection region may be a region that does not overlap with the gasket in the axial direction of the case. The first external terminal may be connected to the terminal plate by welding.

[0023] The conductive cap has a second connection region configured to be connected to 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 region may be a central region of the conductive cap. The second external terminal may be connected to the conductive cap by welding.

[0024] In this manner, in the battery according to the present disclosure, the terminal plate to which the first external terminal is connected, the case connected to the terminal plate, and the first electrode to which they are electrically connected have one polarity (e.g., negative polarity), and the conductive cap to which the second external terminal is connected and the second electrode to which the conductive cap is electrically connected have the other polarity (e.g., positive polarity). In this battery, if an internal short circuit occurs, for example, between the case and the conductive cap, there is a risk of an electrical short circuit between the first external terminal and the second external terminal.

[0025] In contrast, the terminal board according to the present disclosure has a breakable portion disposed between the joint portion with the opening edge of the case and the first connection region. The breakable portion breaks when the internal pressure of the case exceeds a predetermined value, separating the outer and inner breakable portions in the axial direction of the case. When this breakage occurs, the first connection region (included in the inner breakable portion) to which the first external terminal is connected is electrically insulated from the case, which is electrically connected to the terminal board at the joint portion (included in the outer breakable portion). The latter case is electrically connected to the conductive cap to which the second external terminal is connected due to the internal short circuit, but due to this electrical insulation, the first external terminal and the second external terminal are electrically insulated from each other. In other words, the breakable portion according to the present disclosure breaks the current path between the first external terminal and the second external terminal.

[0026] The intended rupture portion may be a first thin-walled portion formed on the terminal plate. The first thin-walled portion may be the thinnest portion of the terminal plate. The first thin-walled portion may be formed by providing a groove or notch in the terminal plate. Such a first thin-walled portion is prone to rupture due to stress concentration when an external force is applied to the terminal plate. This can improve the reliability of the current interruption function of the battery according to the present disclosure.

[0027] The terminal board may have a transition portion where the thickness changes from a first thickness to a second thickness in the radial direction of the case. The first thin-walled portion may be located at or near the transition portion. Stress concentration occurs at such a transition portion when an external force is applied to the terminal board. By locating the first thin-walled portion at or near the transition portion where such stress concentration occurs, the first thin-walled portion can be made more susceptible to fracture. The first thickness may be greater than the thickness of the first thin-walled portion and less than the second thickness. Note that "the first thin-walled portion is located at the transition portion" means that the thinnest portion of the first thin-walled portion and the transition portion overlap each other in the axial direction of the case. Meanwhile, "the first thin-walled portion is located near the transition portion" means that the thinnest portion of the first thin-walled portion and the transition portion are within a range of more than 0 mm and 0.5 mm in the radial direction of the case.

[0028] The first thin-walled portion may be formed around the entire periphery of the terminal plate in the circumferential direction of the case. The thickness of the first thin-walled portion may be uniform around the entire periphery or may vary in parts. Note that a plurality of first thin-walled portions may be formed intermittently on the terminal plate in the circumferential direction of the case.

[0029] The insulating plate has a linear expansion coefficient of 2.0 × 10 at 25 °C. -5 The insulating plate may be made of a thermal expansion material (e.g., polyphenylene sulfide, a copolymer of tetrafluoroethylene and perfluoroalkoxyethylene, etc.) with a thermal expansion coefficient of 0.1 / K or more. The insulating plate may be arranged so as to overlap a region of the terminal plate that is more inward than the intended fracture portion in the axial direction of the case. In this case, the insulating plate expands when the battery generates heat, and the expanding insulating plate pushes up a portion of the terminal plate. This pushing up can promote fracture of the intended fracture portion.

[0030] The conductive cap may have a second thin-walled portion formed thinner than the surrounding area. In the radial direction of the case, the center between the innermost and outermost peripheral portions of the second thin-walled portion may be located closer to the outer periphery than the center between the innermost and outermost peripheral portions of the insulating plate. In the radial direction of the case, the center between the innermost and outermost peripheral portions of the second thin-walled portion may be located closer to the inner periphery than the intended fracture portion of the terminal plate. The second thin-walled portion is prone to deformation within the conductive cap due to stress concentration when the internal pressure of the battery increases. The conductive cap deforms at the second thin-walled portion, pushing up a portion of the terminal plate. This pushing up can promote fracture of the intended fracture portion.

[0031] As described above, according to the present disclosure, a battery having a current interrupt function can be provided by providing a terminal plate with a planned rupture portion. Furthermore, according to the present disclosure, in a battery pack including multiple such batteries, a decrease in output power can be suppressed when an internal short circuit occurs in one of the batteries.

[0032] An example of a battery according to the present disclosure will be specifically described below with reference to the drawings. The components described above can be applied to the components of the example battery described below. The components of the example battery described below can be modified based on the above description. Furthermore, the matters described below may be applied to the above embodiment. Of the components of the example battery described below, components that are not essential to the battery according to the present disclosure may be omitted. Note that the diagrams shown below are schematic and do not accurately reflect the shapes and numbers of actual components.

[0033] The battery 10 of this embodiment is configured as a lithium-ion secondary battery, but is not limited to this. As shown in Figure 1, the battery 10 includes a case 20, an electrode group 30, a sealing unit 50, a terminal plate 60, and an insulating plate 70.

[0034] Case 20 is formed in a cylindrical shape with a bottom and an opening at one end (the upper end in FIG. 1 ), and has a cylindrical side wall portion 21 and a disk-shaped bottom portion 23. A crimping portion 22 for fixing sealing unit 50 is formed in an area of ​​side wall portion 21 near the opening. Case 20 in this embodiment is made of a metal whose main component is iron, but is not limited to this.

[0035] 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 electrode group formed by winding a negative electrode and a positive electrode with a separator interposed therebetween. The electrode group 30 has a cylindrical outer shape. The negative electrode is electrically connected to the bottom 23 of the case 20, and the positive electrode is electrically connected to a current collector plate 54 (described below) of the sealing unit 50 via a positive electrode lead 41. The negative electrode is an example of a first electrode, and the positive electrode is an example of a second electrode.

[0036] The sealing unit 50 seals the opening of the case 20. The sealing unit 50 includes a conductive cap 51, a current collector plate 54, and a gasket 55. The conductive cap 51 is made of metal and is exposed to the outside of the case 20. The current collector plate 54 is also made of metal and is located closer to the electrode group 30 than the conductive cap 51 (lower in FIG. 1 ), and is joined to the conductive cap 51 by, for example, welding. As described above, the current collector plate 54 is electrically connected to the positive electrode of the electrode group 30, and therefore the conductive cap 51 joined to the current collector plate 54 functions as an external positive electrode terminal. The gasket 55 is made of insulating resin and is interposed between the conductive cap 51 and the current collector plate 54 and the crimped portion 22 of the case 20.

[0037] 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 (lower side in FIG. 1 ) than the second insulating plate 82. 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 case 20 and the positive electrode lead 41 to prevent contact between the case 20 and the positive electrode lead 41.

[0038] The terminal plate 60 is joined by welding to the edge of the opening of the case 20 and extends radially inward of the case 20. The terminal plate 60 is made of metal and is exposed to the outside of the case 20. The terminal plate 60 is formed in a circular ring shape. As described above, the case 20 is electrically connected to the negative electrode of the electrode group 30, and therefore the case 20 and the terminal plate 60 joined thereto function as an external negative electrode terminal.

[0039] The insulating plate 70 is disposed between the conductive cap 51 and the terminal plate 60, and electrically insulates them. The insulating plate 70 is formed in a generally circular ring shape. The insulating plate 70 is made of insulating resin with a melting point higher than that of the gasket 55. The insulating plate 70 has a linear expansion coefficient of 2.0×10 at 25° C. -5 The insulating plate 70 is made of a thermal expansion material of at least 1 / K. The outer peripheral edge of the insulating plate 70 is in contact with the gasket 55, but this is not limitative.

[0040] 1 and 2 , the terminal board 60 has a first connection region 61 configured to be connected to a first external terminal 101 (e.g., a first bus bar). The thickness of the first connection region 61 (the length in the vertical direction in FIG. 2 ) may be, for example, 0.5 mm or more and 0.6 mm or less. The terminal board 60 has a transition portion 62 in which the thickness changes from a first thickness (e.g., approximately 0.3 mm) to a second thickness (e.g., approximately 0.4 mm) in the radial direction of the case 20. In the transition portion 62 of this embodiment, the thickness of the terminal board 60 changes stepwise, but this is not limited thereto.

[0041] The conductive cap 51 has a second connection region 52 configured to be connected to a second external terminal 102 (e.g., a second bus bar having a polarity opposite to that of the first bus bar). The second connection region 52 may be, for example, a region of the conductive cap 51 exposed through an opening in the insulating plate 70. The conductive cap 51 has a second thin-walled portion 53 formed to be thinner than its surroundings. In the radial direction of the case 20, the center (indicated by a dashed-dotted line C1) between the innermost and outermost peripheries of the second thin-walled portion 53 is located closer to the outer periphery than the center (indicated by a dashed-dotted line C2) between the innermost and outermost peripheries of the insulating plate 70.

[0042] The terminal plate 60 has a first thin-walled portion 64 provided between a joint portion 63 with the opening edge portion of the case 20 and a first connection region 61. The first thin-walled portion 64 is provided near the transition portion 62 (in this example, slightly closer to the outer periphery than the transition portion). The first thin-walled portion 64 is provided closer to the outer periphery than the outer periphery end of the insulating plate 70. The first thin-walled portion 64 is provided closer to the outer periphery than the outer periphery end of the second thin-walled portion 53. The first thin-walled portion 64 is formed around the entire periphery of the terminal plate 60 in the circumferential direction of the case 20. As shown in FIG. 3 , the first thin-walled portion 64 is configured to break when the internal pressure of the case 20 exceeds a predetermined value, so that a breaking portion 65 on the outer periphery and a breaking portion 66 on the inner periphery are separated in the axial direction of the case 20. Here, if heat is generated inside the case 20 when the internal pressure of the case 20 increases, the insulating plate 70 made of a thermally expansive material expands, pushing up the portion of the terminal plate 60 corresponding to the inner circumferential breaking portion 66, thereby facilitating the breaking. In a similar case, the second thin-walled portion 53 of the conductive cap 51 deforms significantly outward from the case 20, pushing up the portion of the terminal plate 60 corresponding to the inner circumferential breaking portion 66, thereby facilitating the breaking. The first thin-walled portion 64 is an example of a portion intended to break.

[0043] <<Supplementary Note>> The above description of the embodiment discloses the following techniques. a terminal plate joined to an edge of the case opening and extending radially inward of the case; and an insulating plate electrically insulating the conductive cap from the terminal plate, wherein the case and the terminal plate are electrically connected to the first electrode, and the conductive cap is electrically connected to the second electrode, the terminal plate has a first connection region configured to be connected to a first external terminal, and the conductive cap has a second connection region configured to be connected to a second external terminal, and the terminal plate has an intended rupture portion provided between a joint portion with the edge of the case opening and the first connection region, and the intended rupture portion is configured to rupture when an internal pressure of the case exceeds a predetermined value, so that an outer circumferential rupture portion and an inner circumferential rupture portion are separated in the axial direction of the case. (Technology 2) The battery according to Technology 1, wherein the planned rupture portion is a first thin-walled portion formed on the terminal plate. (Technology 3) The battery according to Technology 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-walled portion is located at or near the transition portion. (Technology 4) The battery according to Technology 2 or 3, wherein the first thin-walled portion is formed around the entire periphery of the terminal plate in the circumferential direction of the case. (Technology 5) The insulating plate has a linear expansion coefficient of 2.0 x 10 at 25°C -5 The battery according to any one of techniques 1 to 4, wherein the conductive cap has a second thin-walled portion formed thinner than the surrounding area, and the center between the innermost and outermost peripheries of the second thin-walled portion is located closer to the outer periphery than the center between the innermost and outermost peripheries of the insulating plate in the radial direction of the case.

[0044] While the present invention has been described in terms of presently preferred embodiments, such disclosure is not to be interpreted as limiting. Various changes and modifications will no doubt become apparent to those skilled in the art to which the present invention pertains upon reading the above disclosure. It is therefore intended that the appended claims be interpreted to cover all changes and modifications that do not depart from the true spirit and scope of the invention.

[0045] The present disclosure can be used in batteries.

[0046] 10: Battery 20: Case 21: Side wall portion 22: Crimping portion 23: Bottom portion 30: Electrode group 41: Positive electrode lead 50: Sealing unit 51: Conductive cap 52: Second connection region 53: Second thin-walled portion 54: Current collector plate 55: Gasket 60: Terminal plate 61: First connection region 62: Transition portion 63: Joint portion 64: First thin-walled portion (prospective fracture portion) 65: Fracture portion on outer periphery side 66: Fracture portion on inner periphery side 70: Insulating plate 81: First insulating plate 82: Second insulating plate 101: First external terminal 102: Second external terminal

Claims

1. A battery comprising: a cylindrical case with a bottom 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 cap and sealing the opening; a terminal plate joined to the edge of the opening of the case and extending radially inward of the case; and an insulating plate that electrically insulates the conductive cap from the terminal plate; wherein the case and the terminal plate are electrically connected to the first electrode, and the conductive cap is electrically connected to the second electrode, the terminal plate has a first connection region configured to be connected to a first external terminal, and the conductive cap has a second connection region configured to be connected to a second external terminal, the terminal plate has an intended rupture portion provided between the joint portion with the edge of the opening of the case and the first connection region, and the intended rupture portion is configured to rupture when the internal pressure of the case exceeds a predetermined value, so that the rupture portion on the outer periphery and the rupture portion on the inner periphery are separated in the axial direction of the case.

2. The battery according to claim 1, wherein the intended rupture portion is a first thin-walled portion formed on 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-walled portion is located at or near the transition portion.

4. The battery according to claim 2 or 3, wherein the first thin-walled portion is formed around the entire periphery of the terminal plate in the circumferential direction of the case.

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

6. A battery as claimed in any one of claims 1 to 3, wherein the conductive cap has a second thin-walled portion formed thinner than the surrounding area, and in the radial direction of the case, the centre between the innermost and outermost peripheries of the second thin-walled portion is located closer to the periphery than the centre between the innermost and outermost peripheries of the insulating plate.

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