Battery and battery manufacturing method

Abstract

The battery disclosed herein comprises: wound electrode groups each having a belt-like first electrode (21), a second electrode, and a separator; and a first current collector plate (60) electrically connected to the first electrode (21). The first electrode (21) has at least one first portion (24) welded to the first current collector plate (60), and at least one second portion (25) positioned next to the at least one first portion (24) in the radial direction of the electrode group and separated from the first current collector plate (60).

Description

Battery and method for manufacturing the battery CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This disclosure claims the benefit of priority to Japanese Patent Application No. 2024-048329, filed on March 25, 2024, in the Japan Patent Office, the entire contents of which are incorporated herein by reference.

[0002] The present disclosure relates to batteries and methods for manufacturing batteries.

[0003] BACKGROUND ART Conventionally, a battery has been known that includes a wound electrode group formed by winding a first electrode, a second electrode, and a separator, and a current collector plate electrically connected to the first electrode (for example, Patent Document 1). Patent Document 1 discloses a cylindrical battery comprising: a wound electrode assembly in which at least one first electrode plate and at least one second electrode plate are wound with a separator interposed therebetween; a bottomed cylindrical outer can that houses the electrode assembly; and a first electrode terminal attached to an opening of the outer can via a first insulating member so as to close the opening, wherein the first electrode plate has a first core made of a conductive material and a first active material layer formed on the first core, one side of the first core facing the first electrode terminal being led out from one side of the first active material layer facing the first electrode terminal to form a first lead-out portion, the first lead-out portion including a first bent portion bent toward the inner periphery or the outer periphery of the electrode assembly, a first surface of a first electrode collector plate being in contact with a side surface of the first bent portion facing the first electrode terminal, and the first electrode terminal being connected to a second surface of the first electrode collector plate directly or via a conductive member.

[0004] International Publication No. 2019 / 194182

[0005] The first electrode and the current collector plate of the electrode group are sometimes connected by welding. During this welding, a portion of the first electrode melts and adheres to another portion of the first electrode, resulting in minute metallic foreign matter adhering to the other portion. Such metallic foreign matter peels off relatively easily, which may cause an internal short circuit in the battery. In such a situation, one of the objectives of the present disclosure is to suppress internal short circuits.

[0006] One aspect of the present disclosure relates to a battery including: a wound electrode group having a first electrode, a second electrode, and a separator, each of which is strip-shaped; and a first current collector plate electrically connected to the first electrode, wherein the first electrode has at least one first portion welded to the first current collector plate and at least one second portion positioned adjacent to the at least one first portion in a radial direction of the electrode group and spaced apart from the first current collector plate.

[0007] Another aspect of the present disclosure relates to a method for manufacturing a battery, the method comprising: a laser cutting step of cutting a portion of the first electrode corresponding to the at least one second portion with a laser; and a winding step of winding the cut first electrode, the second electrode, and the separator to form the electrode group.

[0008] According to the present disclosure, it is possible to suppress internal short circuits. 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 invention, will be better understood from the following detailed description taken in conjunction with the drawings.

[0009] 1 is a longitudinal cross-sectional view schematically illustrating an example of a battery according to the present disclosure. It is a top view schematically illustrating a first electrode and a first current collector plate of an electrode group, with the first portion indicated by a solid line, the second portion indicated by a dashed line, and the first current collector plate indicated by a two-dot chain line. It is a cross-sectional view schematically illustrating a connection portion between the first electrode and the first current collector plate, corresponding to line III-III in FIG. 2.

[0010] The following describes an example of a battery and a method for manufacturing the battery according to the present disclosure. However, the present disclosure is not limited to the example described below. While the following description may use specific numerical values ​​and materials, other numerical values ​​and materials may be used as long as the effects of the present disclosure are obtained.

[0011] (Battery) 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 battery also includes an electricity storage device (e.g., a lithium-ion capacitor, an electric double layer capacitor) in which at least one of the positive electrode and the negative electrode is a polarizable electrode that generates capacity through a non-Faradic reaction. The battery according to the present disclosure includes an electrode group and a first current collector plate.

[0012] The electrode group includes a first electrode, a second electrode, and a separator, each of which is strip-shaped (or long sheet-shaped). The electrode group is formed by winding the first electrode and the second electrode with the separator interposed therebetween. In other words, the electrode group is a wound electrode group having the first electrode, the second electrode, and a separator interposed between the two electrodes. The electrode group has a columnar outer shape, which may be, for example, a cylindrical or rectangular columnar 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.

[0013] The first electrode may have a strip-shaped first current collector and a first active material layer supported on the first current collector. The second electrode may have a strip-shaped second current collector and a second active material layer supported on the second current collector. The separator may be composed of a porous sheet that is ion-permeable and insulating. Examples of porous sheets include a thin film, woven fabric, and nonwoven fabric having micropores.

[0014] In the following description of a lithium-ion battery, the first active material layer may be provided on both sides of the first current collector or on one side of the first current collector. When the first electrode is a positive electrode, the first current collector is a positive electrode current collector (e.g., aluminum foil or aluminum alloy foil), and the first active material layer is a positive electrode active material layer (e.g., containing a lithium-containing transition metal oxide). When the first electrode is a negative electrode, the first current collector is a negative electrode current collector (e.g., copper foil or copper alloy foil), and the first active material layer may be a negative electrode active material layer (e.g., containing a carbonaceous material).

[0015] The first current collector plate is electrically connected to the first electrode of the electrode group. When the first electrode is a positive electrode, the first current collector plate is a positive electrode current collector plate (e.g., made of stainless steel, titanium, a titanium alloy, aluminum, or an aluminum alloy). When the first electrode is a negative electrode, the first current collector plate is a negative electrode current collector plate (e.g., made of nickel, a nickel alloy, copper, or a copper alloy). The first current collector plate may be electrically connected to the first electrode by any type of welding (e.g., laser welding or resistance welding). The surface of the first current collector plate may be plated to improve weldability (e.g., lead-tin plating, nickel-tin plating, zinc-nickel plating, chrome plating, zinc plating, nickel plating, etc.).

[0016] The first electrode has at least one first portion and at least one second portion. The at least one first portion is welded to the first current collector plate. The at least one second portion is located adjacent to the at least one first portion in the radial direction of the electrode group (hereinafter simply referred to as the radial direction) and is spaced apart from the first current collector plate. That is, the at least one first portion is welded to the first current collector plate, while the at least one second portion is not welded to the first current collector plate. The weld between the at least one first portion and the first current collector plate may extend along the radial direction. Because at least one second portion spaced apart from the first current collector plate is located adjacent to the at least one first portion, even if a portion of the at least one first portion melts when welding the at least one first portion to the first current collector plate, it is unlikely to adhere to the adjacent second portion. Therefore, metallic foreign matter that could cause an internal short circuit is unlikely to be generated, and internal short circuits in the battery can be suppressed.

[0017] The first electrode may have a strip-shaped first current collector and a first active material layer supported on the first current collector. The first current collector may have a first exposed portion exposed from the first active material layer. In other words, the first current collector may have a first covering portion supporting the first active material layer and a first exposed portion not supporting the first active material layer. The first exposed portion may be disposed at one end of the first current collector in the short-side direction (or in the winding axis direction of the electrode group). At least one first portion and at least one second portion may be included in the first exposed portion. In this configuration, the first active material layer is not removed in the second portion, thereby maintaining a high battery capacity. However, at least one second portion may be included in the portion of the first current collector where the first active material layer is provided.

[0018] At least one first portion may have a bent portion welded to the first current collector plate in surface contact therewith. This reduces the connection resistance between the at least one first portion and the first current collector plate, i.e., the connection resistance between the first electrode and the first current collector plate, thereby reducing the internal resistance of the battery. Such a bent portion may be formed using a predetermined tool (e.g., a roller) after winding the first electrode, the second electrode, and the separator. The bent portion may be formed by bending a part of the first portion radially inward. However, at least one first portion may not have such a bent portion.

[0019] The at least one first portion may include a plurality of first portions. The at least one second portion may include a plurality of second portions. In at least a portion of the first electrode, the plurality of first portions and the plurality of second portions may be arranged alternately in the radial direction. In this case, the connection resistance between the first electrode and the first current collector plate can be reduced while obtaining the technical effect of the present disclosure. Note that the plurality of first portions and the plurality of second portions may be arranged side by side in any order in the radial direction.

[0020] The battery may further include a second current collector plate electrically connected to the second electrode. The second electrode may have at least one third portion welded to the second current collector plate and at least one fourth portion located adjacent to the third portion in the radial direction and spaced apart from the second current collector plate. That is, in this configuration, a relationship similar to that between the first electrode and the first current collector plate also holds between the second electrode and the second current collector plate. Therefore, the technical effect of the present disclosure can be achieved between the second electrode and the second current collector plate. Note that the battery may not include a second current collector plate, in which case an electrode lead may be connected to the second electrode.

[0021] The second electrode may include a strip-shaped second current collector and a second active material layer supported on the second current collector. The second current collector may have a second exposed portion exposed from the second active material layer. In other words, the second current collector may have a second covering portion supporting the second active material layer and a second exposed portion not supporting the second active material layer. The second exposed portion may be disposed at one end of the second current collector in the short direction (or in the winding axis direction of the electrode group). At least one third portion and at least one fourth portion may be included in the second exposed portion. In this configuration, the second active material layer is not removed in the fourth portion, thereby maintaining a high battery capacity. However, at least one fourth portion may be included in the portion of the second current collector where the second active material layer is provided.

[0022] The first electrode may be a negative electrode of a lithium-ion secondary battery or a lithium metal secondary battery. The first current collector may be made of a material containing iron or copper. In this configuration, the second electrode is a positive electrode, and if the battery includes a second current collector, the second current collector may be made of a material containing aluminum.

[0023] The first electrode may be a positive electrode of a lithium-ion secondary battery or a lithium metal secondary battery. The first current collector may be made of a material containing aluminum. In this configuration, the second electrode is a negative electrode, and if the battery includes a second current collector, the second current collector may be made of a material containing iron or copper.

[0024] (Battery Manufacturing Method) A battery manufacturing method according to the present disclosure is a method for manufacturing the above-described battery, and includes a laser cutting step and a winding step.

[0025] In the laser cutting step, a portion of the first electrode corresponding to at least one second portion is cut by a laser. The portion corresponding to the second portion may have a rectangular shape in the first electrode in the deployed state, but is not limited to this.

[0026] In the winding step, the cut first electrode, the second electrode, and the separator are wound together to form an electrode assembly, thereby obtaining an electrode assembly having a first electrode including at least one first portion and at least one second portion. The winding step may be performed after the laser cutting step.

[0027] The battery manufacturing method may further include a laser welding step of welding at least one first portion and a first current collector plate by a laser, wherein the laser welding step may include welding at least one first portion and a first current collector plate by scanning a laser along a radial direction of the electrode group.

[0028] As described above, according to the present disclosure, by providing at least one second portion spaced apart from the first current collector plate, it is possible to suppress internal short circuits in the battery.

[0029] An example of a battery and a method for manufacturing a battery according to the present disclosure will be described in detail below with reference to the drawings. The components and steps described above can be applied to the components and steps of the example battery and method for manufacturing a battery described below. The components and steps of the example battery and method for manufacturing a 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 and steps of the example battery and method for manufacturing a battery described below, components and steps that are not essential to the battery and method for manufacturing a 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.

[0030] 1 to 3 , the battery 10 includes a wound electrode group 20, a first current collector plate 60, a second current collector plate 70, a case 40, and a sealing plate 51.

[0031] The electrode group 20 is formed by winding a strip-shaped first electrode 21 and a strip-shaped second electrode 26 with a strip-shaped separator 32 interposed therebetween. In this embodiment, the first electrode 21 is a positive electrode and the second electrode 26 is a negative electrode, but this is not limited thereto. The separator 32 is exposed at the outermost periphery of the electrode group 20, but this is not limited thereto. For example, a first current collector 22 or a second current collector 27, which will be described later, may be exposed at the outermost periphery of the electrode group 20.

[0032] The first electrode 21 has a strip-shaped first current collector 22 and a first active material layer (not shown) provided on the surface of the first current collector 22. In this embodiment, the first active material layer is provided on both sides of the first current collector 22, but this is not limitative. The first current collector 22 is made of, for example, aluminum foil or aluminum alloy foil.

[0033] The first current collector 22 is located at one end (the upper end in FIG. 1 ) in a direction perpendicular to the longitudinal direction of the first current collector 22 and has a first exposed portion 23 exposed from the first active material layer. The first exposed portion 23 has a plurality of first portions 24 welded to the first current collector plate 60 and a plurality of second portions 25 located adjacent to the plurality of first portions 24 in the radial direction of the electrode group 20 and spaced apart from the first current collector plate 60. In this embodiment, the plurality of first portions 24 have bent portions 24 a welded to the first current collector plate 60 in surface contact therewith, but this is not limited thereto. In this embodiment, in at least a portion of the first exposed portion 23, the plurality of first portions 24 and the plurality of second portions 25 are arranged alternately in the radial direction, but this is not limited thereto.

[0034] The second electrode 26 has a strip-shaped second current collector 27. In this embodiment, the second electrode 26 further has a second active material layer (not shown) provided on the surface of the second current collector 27, but is not limited to this. The second current collector 27 is made of, for example, copper foil or copper alloy foil.

[0035] The second current collector 27 is located at one end (the lower end in FIG. 1 ) in a direction perpendicular to the longitudinal direction of the second current collector 27 and has a second exposed portion 28 exposed from the second active material layer. The second exposed portion 28 has a plurality of third portions 29 welded to the second current collector plate 70 and a plurality of fourth portions 31 located adjacent to the plurality of third portions 29 in the radial direction of the electrode group 20 and spaced apart from the second current collector plate 70. In this embodiment, the plurality of third portions 29 have bent portions 29 a welded to the second current collector plate 70 in surface contact therewith, but this is not limited to this. In this embodiment, in at least a portion of the second exposed portion 28, the plurality of third portions 29 and the plurality of fourth portions 31 are arranged alternately in the radial direction, but this is not limited to this.

[0036] The first current collector 60 is connected to the first exposed portion 23 by welding and is electrically connected to the first current collector 22. The first current collector 60 is made of, for example, a material containing aluminum (e.g., aluminum or an aluminum alloy). The first current collector 60 is generally cross-shaped overall and has multiple (four in this example) arm portions 61.

[0037] The second current collector 70 is connected to the second exposed portion 28 by welding and is electrically conductive with the second current collector 27. The second current collector 70 is made of, for example, a material containing iron (e.g., stainless steel) or a material containing copper (e.g., copper or a copper alloy). The second current collector 70 is generally cross-shaped overall and has multiple (four in this example) arm portions (not shown).

[0038] The case 40 is made of metal and is formed into a cylindrical shape with a bottom and an opening at one end (the upper end in FIG. 1 ). A welding member 41 is provided on the inner bottom surface of the case 40, and the second current collector plate 70 is welded to this welding member 41. Therefore, the case 40 of this embodiment functions as an external negative electrode terminal.

[0039] The sealing plate 51 seals the opening of the case 40. A gasket 52 is disposed around the periphery of the sealing plate 51, and the inside of the case 40 is sealed by crimping the open edge of the case 40 to the gasket. The sealing plate 51 is electrically connected to the first current collector plate 60 via a metal tab 53. Thus, the sealing plate 51 of this embodiment functions as an external positive electrode terminal.

[0040] (Battery Manufacturing Method) The battery manufacturing method of this embodiment is a method for manufacturing the above-described battery 10, and includes a laser cutting step, a winding step, and a laser welding step.

[0041] In the laser cutting process, portions of the first exposed portion 23 corresponding to the plurality of second portions 25 are cut by a laser. Also, in the laser cutting process, portions of the second exposed portion 28 corresponding to the plurality of fourth portions 31 are cut by a laser.

[0042] However, in the laser cutting step, if a portion of first electrode 21 corresponding to at least one second portion 25 is cut, the region where the first active material layer is provided may be cut in addition to first exposed portion 23. Furthermore, in the laser cutting step, if a portion of second electrode 26 corresponding to at least one fourth portion 31 is cut, the region where the second active material layer is provided may be cut in addition to second exposed portion 28.

[0043] In the winding step, the cut first electrode 21 , the cut second electrode 26 , and the separator 32 are wound together to form the electrode group 20 .

[0044] In the laser welding step, the plurality of first portions 24 are welded to the first current collector plate 60 by a laser. In addition, in the laser welding step, the plurality of third portions 29 are welded to the second current collector plate 70 by a laser.

[0045] <<Supplementary Notes>> The above embodiments disclose the following technologies. (Technology 1) A battery comprising: a wound electrode group having a strip-shaped first electrode, a strip-shaped second electrode, and a separator; and a first current collector plate electrically connected to the first electrode, wherein the first electrode has: at least one first portion welded to the first current collector plate; and at least one second portion located adjacent to the at least one first portion in the radial direction of the electrode group and spaced apart from the first current collector plate. (Technology 2) The battery according to Technology 1, wherein the first electrode has a strip-shaped first current collector and a first active material layer carried on the first current collector, wherein the first current collector has a first exposed portion exposed from the first active material layer, and the at least one first portion and the at least one second portion are included in the first exposed portion. (Technology 3) The battery according to Technology 1 or 2, wherein the at least one first portion has a bent portion that is in surface contact with and welded to the first current collector plate. (Technology 4) The battery according to any one of Technology 1 to 3, wherein the at least one first portion includes a plurality of first portions, the at least one second portion includes a plurality of second portions, and in at least a part of the first electrode, the plurality of first portions and the plurality of second portions are arranged alternately in the radial direction. (Technology 5) The battery according to any one of Technology 1 to 4, further comprising a second current collector plate electrically connected to the second electrode, wherein the second electrode has: at least one third portion welded to the second current collector plate, and at least one fourth portion located adjacent to the at least one third portion in the radial direction and spaced apart from the second current collector plate. (Technology 6) The battery according to Technology 5, wherein the second electrode has a strip-shaped second current collector and a second active material layer supported on the second current collector, the second current collector has a second exposed portion exposed from the second active material layer, and the at least one third portion and the at least one fourth portion are included in the second exposed portion. (Technology 7) The battery according to any one of Technology 1 to 6, wherein the first electrode is a negative electrode of a lithium ion secondary battery or a lithium metal secondary battery, and the first current collector is made of a material containing iron or copper.(Technology 8) The battery according to any one of Technologies 1 to 6, wherein the first electrode is a positive electrode of a lithium ion secondary battery or a lithium metal secondary battery, and the first current collector plate is made of a material containing aluminum. (Technology 9) A method for manufacturing the battery according to any one of Technologies 1 to 8, comprising: a laser cutting step of cutting a portion of the first electrode corresponding to the at least one second portion with a laser; and a winding step of winding the cut first electrode, the second electrode, and the separator to form the electrode group. (Technology 10) The method for manufacturing the battery according to Technology 9, further comprising a laser welding step of welding the at least one first portion and the first current collector plate with a laser.

[0046] The present disclosure can be used in batteries and methods for manufacturing batteries.

[0047] 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.

[0048] 10: Battery 20: Electrode group 21: First electrode 22: First current collector 23: First exposed portion 24: First portion 24a: Folded portion 25: Second portion 26: Second electrode 27: Second current collector 28: Second exposed portion 29: Third portion 29a: Folded portion 31: Fourth portion 32: Separator 40: Case 41: Welding member 51: Sealing plate 52: Gasket 53: Metal tab 60: First current collector plate 61: Arm portion 70: Second current collector plate

Claims

1. A battery comprising: a wound electrode group having a strip-shaped first electrode, a strip-shaped second electrode, and a separator; and a first current collector plate electrically connected to the first electrode, wherein the first electrode has at least one first portion welded to the first current collector plate, and at least one second portion located adjacent to the at least one first portion in the radial direction of the electrode group and spaced apart from the first current collector plate.

2. The battery according to claim 1, wherein the first electrode comprises a strip-shaped first current collector and a first active material layer supported on the first current collector, the first current collector has a first exposed portion exposed from the first active material layer, and the at least one first portion and the at least one second portion are included in the first exposed portion.

3. The battery according to claim 1 or 2, wherein the at least one first portion has a bent portion that is welded to the first current collector plate in surface contact therewith.

4. The battery according to claim 1 or 2, wherein the at least one first portion includes a plurality of first portions, the at least one second portion includes a plurality of second portions, and in at least a portion of the first electrode, the plurality of first portions and the plurality of second portions are alternately arranged in the radial direction.

5. The battery according to claim 1 or 2, further comprising a second current collector plate electrically connected to the second electrode, the second electrode having at least one third portion welded to the second current collector plate, and at least one fourth portion located adjacent to the at least one third portion in the radial direction and spaced apart from the second current collector plate.

6. The battery according to claim 5, wherein the second electrode comprises a strip-shaped second current collector and a second active material layer supported on the second current collector, the second current collector has a second exposed portion exposed from the second active material layer, and the at least one third portion and the at least one fourth portion are included in the second exposed portion.

7. The battery according to claim 1 or 2, wherein the first electrode is a negative electrode of a lithium ion secondary battery or a lithium metal secondary battery, and the first current collector plate is made of a material containing iron or copper.

8. The battery according to claim 1 or 2, wherein the first electrode is a positive electrode of a lithium ion secondary battery or a lithium metal secondary battery, and the first current collector plate is made of a material containing aluminum.

9. A method for manufacturing a battery as defined in claim 1 or 2, comprising: a laser cutting step of cutting a portion of the first electrode corresponding to the at least one second portion with a laser; and a winding step of winding the cut first electrode, the second electrode, and the separator to form the electrode group.

10. The method for manufacturing a battery according to claim 9, further comprising a laser welding step of welding the at least one first portion and the first current collector plate with a laser.

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