Battery

Abstract

Disclosed is a battery 10 which is provided with: a case 20; an electrode group which is contained in the case 20 and comprises a first electrode and a second electrode; and a sealing unit 50 which seals the opening of the case 20. The case 20 is electrically connected to the first electrode and has a crimped part 22 which fixes the sealing unit 50. The sealing unit 50 comprises: a collector plate 54 which is electrically connected to the second electrode; a conductive cap 51 which is disposed further toward the outer side of the collector plate 54 in the axial direction of the case 20, and is bonded to the collector plate 54 at a first bonding part J; an insulating gasket 55 which is interposed among the crimped part 22, the collector plate 54 and the conductive cap 51; and an insulating member 56 which comprises a first insulating part 56a that is disposed between the peripheral edge part of the collector plate 54 and the peripheral edge part of the conductive cap 51. The first insulating part 56a is disposed closer to the outer periphery than the first bonding part J. Consequently, the present invention is capable of suppressing internal short-circuiting upon combustion.

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 unit that seals the case opening. The sealing unit includes a sealing body formed by stacking, in order from the electrode group side, a filter, a lower valve body, an insulator, an upper valve body, and a cap, and a gasket provided between the case and the sealing body.

[0003] Japanese Patent Application Laid-Open No. 2019-153388

[0004] However, batteries may burn in the event of an abnormality. When combustion occurs, the heat can melt the gasket, causing contact between the sealing body and the case, resulting in electrical conduction. Such electrical conduction or internal short circuit is particularly problematic in battery packs containing multiple batteries. This is because a large current flows from the other batteries into the burned battery, reducing the output of the battery pack. In this situation, one of the objectives of the present disclosure is to suppress internal short circuits during combustion.

[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 including a first electrode and a second electrode; and a sealing unit sealing the opening, the case having a crimping portion for fixing the sealing unit and electrically connecting the first electrode; the sealing unit including a current collector plate electrically connecting the second electrode; a conductive cap disposed axially outward of the case relative to the current collector plate and joined to the current collector plate at a first joint; an insulating gasket interposed between the crimping portion, the current collector plate, and the conductive cap; and an insulating member including a first insulating portion disposed between a peripheral edge of the current collector plate and a peripheral edge of the conductive cap, the first insulating portion being disposed closer to the outer periphery than the first joint.

[0006] According to the present disclosure, it is possible to suppress internal short circuits during combustion.

[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 short circuit suppression 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, and a sealing unit. 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 case has a crimping portion for fixing the sealing unit, and is electrically connected to the first electrode of the electrode group, so that the case functions as one external terminal of the battery.

[0018] The sealing unit seals the opening of the case. The sealing unit has a current collector plate, a conductive cap, an insulating gasket, and an insulating member. The current collector plate is electrically connected to the second electrode of the electrode group. The conductive cap is disposed axially outward of the case than the current collector plate and is joined to the current collector plate at a first joint. Thus, the conductive cap functions as the other external terminal of the battery. The gasket is interposed between the crimping portion and the current collector plate and the conductive cap. The gasket may be made of, for example, polypropylene. The insulating member includes a first insulating portion disposed between the peripheral edge of the current collector plate and the peripheral edge of the conductive cap. The first insulating portion is disposed closer to the outer periphery than the first joint.

[0019] The first insulating portion is desirably made of a material with higher heat resistance than the gasket. For example, the first insulating portion may contain, as a main component, a resin material with a higher melting point or deflection temperature under load than the gasket, or may contain, as a main component, ceramics, or may be made of a cured product of a thermosetting resin composition. The deflection temperature under load may be measured by a deflection temperature under load measurement method conforming to ASTM-D648 of the American Society for Testing and Materials. The main component may be a component that constitutes 50% or more by mass of the first insulating portion, or may be a component that constitutes 70% or more by mass. The insulating member including the first insulating portion may be made of, for example, polyphenylene sulfide or a copolymer of tetrafluoroethylene and perfluoroalkoxyethylene, which have high sealing properties and heat resistance.

[0020] Here, if the battery burns, the gasket melts, causing the conductive components of the sealing unit (particularly the current collector plate) to come into contact with the crimped portion of the case, which could result in an internal short circuit. However, the sealing unit according to the present disclosure has an insulating member including a first insulating portion located outside the gasket, in a position less susceptible to combustion. Such a first insulating portion is less likely to melt or burn even during battery combustion, and its presence between the peripheral edge of the current collector plate and the peripheral edge of the conductive cap allows the conductive cap to remain insulated from the current collector plate and the case even if the current collector plate comes into contact with the crimped portion of the case. Furthermore, during battery combustion, the first joint between the current collector plate and the conductive cap may be broken by the heat of combustion and / or thermal expansion of the first insulating portion. Therefore, internal short circuits during combustion can be suppressed.

[0021] The insulating member may further include a second insulating portion extending from the outer peripheral end of the first insulating portion in the axial direction of the case and positioned between the conductive cap and the gasket. That is, the second insulating portion is positioned radially outward of the peripheral edge of the conductive cap, and a portion of the gasket is located further radially outward of the second insulating portion. The second insulating portion may primarily contain a resin material having a higher melting point or deflection temperature under load than the gasket, may primarily contain ceramics, or may be composed of a cured product of a thermosetting resin composition. With this configuration, even if the gasket radially outward of the peripheral edge of the conductive cap melts during combustion, the second insulating portion can prevent the peripheral edge of the conductive cap from contacting the crimped portion of the case.

[0022] The insulating member may further include a third insulating portion extending radially inward from an end of the second insulating portion of the case and positioned between the conductive cap and the gasket. That is, the third insulating portion is positioned axially outward from the peripheral edge of the conductive cap, and a portion of the gasket is located axially further outward from the third insulating portion. The third insulating portion may primarily contain a resin material having a higher melting point or deflection temperature under load than the gasket, may primarily contain ceramics, or may be composed of a cured product of a thermosetting resin composition. With this configuration, even if the gasket axially outward from the peripheral edge of the conductive cap melts during combustion, the third insulating portion can prevent the peripheral edge of the conductive cap from contacting the crimped portion of the case.

[0023] The insulating member has a linear expansion coefficient of 2.0 × 10 at 25 °C. -5 The first insulating portion may be made of a thermal expansion material having a thermal expansion coefficient of 1 / K or more. In this case, the first insulating portion expands significantly when the battery burns, which easily releases the bonded state of the first joint. Therefore, even if the portion of the current collector plate corresponding to the first joint does not melt due to the heat of combustion, the current collector plate and the conductive cap can easily be electrically insulated from each other.

[0024] The radial distance from the outer peripheral edge of the conductive cap to the inner peripheral end of the first insulating portion may be 0.25D or more, where D is the radial distance from the outer peripheral edge of the conductive cap to the first joint portion. With this configuration, the inner peripheral end of the first insulating portion is located relatively close to the first joint portion. Therefore, expansion of the first insulating portion during battery combustion easily causes the current collector plate and the conductive cap to separate from each other at the first joint portion, easily releasing the bonded state of the first joint portion. Note that the radial distance from the outer peripheral edge of the conductive cap to the inner peripheral end of the first insulating portion may 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.

[0025] As described above, according to the present disclosure, by providing an insulating member at a position where it is less susceptible to combustion than the gasket, it is possible to suppress an internal short circuit during combustion.

[0026] 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.

[0027] The battery 10 of this embodiment is configured as a lithium-ion secondary battery, but is not limited to this. As shown in Figures 1 and 2, the battery 10 includes a case 20, an electrode group 30, and a sealing unit 50.

[0028] 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.

[0029] 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. Therefore, the case 20 functions as an external negative electrode terminal. 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.

[0030] 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 disposed axially outward of the case 20 relative to the current collector plate 54. The conductive cap 51 is exposed to the outside of the case 20. The current collector plate 54 is also made of metal and is joined to the conductive cap 51 at a first joint J, for example, by 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, the current collector plate 54, and the crimping portion 22.

[0031] The sealing unit 50 further includes an insulating member 56 having a melting point or a deflection temperature under load higher than that of the gasket 55. The insulating member 56 has a linear expansion coefficient of 2.0×10 at 25° C. -5 The insulating member 56 is made of a thermal expansion material of 0.1 / K or more, but is not limited to this. For example, the insulating member 56 may contain ceramics as a main component. The insulating member 56 is disposed closer to the outer periphery than the first joint 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 of the current collector plate 54 and the peripheral edge of the conductive cap 51. The second insulating portion 56b extends from the outer peripheral end of the first insulating portion 56a in the axial direction of the case 20 (upward in FIG. 1 ) and is positioned between the conductive cap 51 and the gasket 55. The third insulating portion 56c extends from the end (upper end in FIG. 1 ) of the second insulating portion 56b radially inward of the case 20 and is positioned between the conductive cap 51 and the gasket 55.

[0032] If the radial distance from the outer peripheral edge of the conductive cap 51 to the first joint J is D, the radial distance from the outer peripheral edge of the conductive cap 51 to the inner peripheral end of the first insulating portion 56a is 0.25D or more, preferably 0.5D or more, and more preferably 0.8D or more.

[0033] 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.

[0034] FIG. 3 shows the battery 10 of this embodiment before and after combustion. As shown in the figure, if combustion occurs in the battery 10, the gasket 55 may melt, causing the peripheral edge of the current collector 54 to come into contact with the case 20. However, in the battery 10 of this embodiment, the insulating member 56, which has a high melting point or deflection temperature under load, is interposed between the peripheral edge of the current collector 54 and the peripheral edge of the conductive cap 51, thereby preventing electrical conduction between the case 20 and the conductive cap 51. Note that the inner peripheral region of the current collector 54 may melt during combustion, but may remain unmelted. In the latter case, electrical conduction between the case 20 and the conductive cap 51 may occur via the first joint J. However, the insulating member 56 of this embodiment expands significantly due to the heat generated during combustion, causing the first joint J to break. As described above, the battery 10 of this embodiment can prevent internal short circuits during combustion.

[0035] <<Supplementary Note>> The above embodiments disclose the following technology: (Technology 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, and a sealing unit sealing the opening, wherein the case has a crimping portion for fixing the sealing unit and is electrically connected to the first electrode, and the sealing unit comprises: a current collector plate electrically connected to the second electrode, a conductive cap arranged axially outward of the case than the current collector plate and joined to the current collector plate at a first joint, an insulating gasket interposed between the crimping portion, and the current collector plate and the conductive cap, and an insulating member including a first insulating portion arranged between a peripheral edge of the current collector plate and a peripheral edge of the conductive cap, wherein the first insulating portion is arranged closer to the outer periphery than the first joint. (Technology 2) The battery according to Technology 1, wherein the insulating member further includes a second insulating portion extending from an outer peripheral end of the first insulating portion in the axial direction of the case and positioned between the conductive cap and the gasket. (Technology 3) The battery according to Technology 2, wherein the insulating member further includes a third insulating portion extending from an end of the second insulating portion toward the inside in the radial direction of the case and positioned between the conductive cap and the gasket. (Technology 4) The insulating member has a linear expansion coefficient of 2.0 x 10 at 25°C -5 / K or more. (Technology 5) The battery according to any one of Techniques 1 to 3, wherein the battery is made of a thermal expansion material having a thermal expansion coefficient of 0.25D or more. (Technology 6) The battery according to any one of Techniques 1 to 5, wherein the first insulating portion has a melting point or a deflection temperature under load higher than that of the gasket. (Technology 7) The battery according to any one of Techniques 1 to 6, wherein the first insulating portion includes a ceramic.

[0036] 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.

[0037] The present disclosure can be used in batteries.

[0038] 10: Battery 20: Case 21: Side wall 22: Caulking portion 23: Bottom 30: Electrode group 41: Positive electrode lead 50: Sealing unit 51: Conductive cap 54: Current collector plate 55: Gasket 56: Insulating member 56a: First insulating portion 56b: Second insulating portion 56c: Third insulating portion 81: First insulating plate 82: Second insulating plate J: First joint portion

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; and a sealing unit that seals the opening, wherein the case has a crimping portion that fixes the sealing unit and is electrically connected to the first electrode, and the sealing unit comprises: a current collector plate that is electrically connected to the second electrode; a conductive cap that is positioned axially outward of the case than the current collector plate and joined to the current collector plate at a first joint; an insulating gasket interposed between the crimping portion and the current collector plate and the conductive cap; and an insulating member including a first insulating portion that is positioned between a peripheral edge of the current collector plate and a peripheral edge of the conductive cap, wherein the first insulating portion is positioned closer to the outer periphery than the first joint.

2. The battery according to claim 1, wherein the insulating member further includes a second insulating portion extending from the outer peripheral end of the first insulating portion in the axial direction of the case and positioned between the conductive cap and the gasket.

3. The battery according to claim 2, wherein the insulating member further includes a third insulating portion extending radially inward of the case from an end of the second insulating portion and positioned between the conductive cap and the gasket.

4. The insulating member 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.

5. The battery described in claim 4, wherein the radial distance from the outer peripheral edge of the conductive cap to the first joint portion is D, and the radial distance from the outer peripheral edge of the conductive cap 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, wherein the first insulating portion has a melting point or a deflection temperature under load higher than that of the gasket.

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

Images