Lead member

Abstract

This lead member comprises a conductor foil and a pair of insulating films. The conductor foil has a first main surface extending in a first direction and a second direction orthogonal to the first direction, and a second main surface opposite to the first main surface. The pair of insulating films are stuck to portions of the first main surface and the second main surface so as to extend across both side surfaces of the conductor foil along the first direction. The conductive foil has a rectangular shape of which one corner is a rounded corner in a plan view seen along a third direction orthogonal to the first direction and to the second direction. The side surface of the rounded corner has a shear surface and a fracture surface. The shear surface is adjacent to the first main surface, and the fracture surface is adjacent to the second main surface.

Description

Lead material

[0001] This application claims priority to Japanese Patent Application No. 2024-013187, filed on January 31, 2024, and incorporates by reference all of the contents of said Japanese application.

[0002] Japanese Patent Application Laid-Open No. 2003-144222 discloses lead members that allow the front and back of each lead member to be easily distinguished.

[0003] Utility Model Registration No. 3178500

[0004] A lead member according to an embodiment of the present disclosure includes a conductor foil and a pair of insulating films, the conductor foil having a first main surface extending in a first direction and a second direction perpendicular to the first direction, and a second main surface opposite the first main surface, the pair of insulating films being attached to portions of the first main surface and the second main surface so as to straddle both side surfaces of the conductor foil extending in the first direction, the conductor foil having a rectangular shape with one rounded corner in a plan view seen in a third direction perpendicular to the first and second directions, the side surface of the rounded corner having a shear surface and a fracture surface, the shear surface adjacent to the first main surface, and the fracture surface adjacent to the second main surface.

[0005] Fig. 1 is a perspective view of a lead member according to an embodiment of the present disclosure. Fig. 2 is a perspective view showing an example of a nonaqueous electrolyte battery including the lead member. Fig. 3 is a plan view of the lead member of Fig. 1 as seen along the thickness direction. Fig. 4 is a view showing a side surface of a rounded corner of the lead member of Fig. 1.

[0006] [Problem to be Solved by the Present Disclosure] In the manufacturing process of a lead member, protrusions called burrs may be generated when the conductor foil is cut. For example, if the surface with the burrs is welded to the electrode foil, the electrode foil may break.

[0007] An object of the present disclosure is to provide a lead member with reduced burrs.

[0008] [Advantages of the Present Disclosure] According to the present disclosure, a lead member with small burrs can be provided.

[0009] [Description of Embodiments of the Present Disclosure] First, embodiments of the present disclosure will be described. A lead member according to one embodiment of the present disclosure includes: (1) a conductor foil and a pair of insulating films. The conductor foil has a first main surface extending in a first direction and a second direction perpendicular to the first direction, and a second main surface opposite the first main surface. The pair of insulating films are attached to portions of the first main surface and the second main surface so as to straddle both side surfaces of the conductor foil extending along the first direction. The conductor foil has a rectangular shape with one rounded corner in a plan view seen along a third direction perpendicular to the first and second directions. The side surface of the rounded corner has a sheared surface and a fractured surface, the sheared surface being adjacent to the first main surface, and the fractured surface being adjacent to the second main surface.

[0010] The lead member has one rounded corner, making the shape of the lead member asymmetrical, making it easy to distinguish between the front and back of the lead member. The cut surface has both a shear surface and a fracture surface, which reduces burrs.

[0011] (2) In the lead member of (1) above, the ratio of the area of ​​the fractured surface to the total area of ​​the sheared surface and the fractured surface may be 0.5 or less.

[0012] When the ratio of sheared surfaces to fractured surfaces is within the above range, burrs are small and chipping is unlikely to occur when the corners are rounded.

[0013] (3) In the lead member of (1) or (2) above, the ratio of the area of ​​the fractured surface to the total area of ​​the sheared surface and the fractured surface may be 0.2 or more.

[0014] When the ratio of the shear surface to the fracture surface is within the above range, it is easy to form the shear surface and the fracture surface at a desired area ratio.

[0015] (4) In the lead member according to any one of (1) to (3) above, the area of ​​the sheared surface may be larger than the area of ​​the fractured surface.

[0016] According to the above configuration, burrs are further reduced and chipping is less likely to occur when the corners are rounded.

[0017] (5) In the lead member of any one of (1) to (4) above, the length of the rounded corner portion along the second direction may be longer than the length of the rounded corner portion along the first direction.

[0018] According to the above configuration, the influence of variations in width can be reduced.

[0019] [Details of the embodiment of the present disclosure] Specific examples of the lead member of the present disclosure will be described below with reference to the drawings. The present invention is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims.

[0020] 1 is a perspective view of a lead member 1 according to an embodiment of the present disclosure. In the following description, the X direction in FIG. 1 corresponds to a first direction (length direction), the Y direction corresponds to a second direction (width direction), and the Z direction corresponds to a third direction (thickness direction). The first direction, the second direction, and the third direction are each perpendicular to the other two directions.

[0021] As shown in FIG. 1 , the lead member 1 according to this embodiment includes a conductor foil 2 and an insulating film 3. The conductor foil 2 has a first main surface 2a extending in a first direction and a second direction and a second main surface 2b facing in the opposite direction to the first main surface 2a. The conductor foil 2 has two side surfaces 2c and 2d and two side surfaces 2e and 2f. The side surfaces 2c and 2d connect the first main surface 2a and the second main surface 2b at their respective ends along the first direction. The side surfaces 2e and 2f connect the first main surface 2a and the second main surface 2b at their respective ends along the second direction. As will be described later, in this embodiment, the corners between the side surfaces 2c and 2e of the conductor foil 2 are rounded to form rounded corner portions 21.

[0022] The conductor foil 2 is a conductor for extracting electricity from inside the battery. There are no particular limitations on the material of the conductor foil 2 as long as it is usable as a conductor for a lead member for a nonaqueous electrolyte battery. Examples of materials for the conductor foil 2 include metal materials such as aluminum, titanium, nickel, copper, aluminum alloys, titanium alloys, nickel alloys, and copper alloys, as well as materials obtained by plating any of these metal materials with nickel or gold.

[0023] The dimensions of the conductor foil 2 are not particularly limited, but for example, the length in the first direction may be 10 mm or more and 120 mm or less, the length in the second direction may be 3 mm or more and 120 mm or less, and the thickness may be 0.05 mm or more and 3.0 mm or less.

[0024] The insulating films 3 are attached to both main surfaces of the conductor foil 2 and are used to prevent short circuits between the conductor foil 2 and the sealed container 11 (see FIG. 2 ). More specifically, as shown in FIG. 1 , a pair of insulating films 3, i.e., an insulating film covering a portion of the first main surface 2a and an insulating film covering a portion of the second main surface 2b, are bonded to each other at the end of the lead member 1 in the second direction. The insulating films 3 cover portions of the first main surface 2a, the second main surface 2b, the side surfaces 2c, and the side surfaces 2d, excluding the side surfaces 2e and 2f. The pair of insulating films are attached to portions of the first main surface 2a and the second main surface 2b of the conductor foil 2 so as to straddle both side surfaces (side surfaces 2c and 2d) of the conductor foil 2 along the first direction.

[0025] Fig. 2 is a perspective view showing a nonaqueous electrolyte battery 10 including a lead member 1. The nonaqueous electrolyte battery 10 is configured by housing a laminated electrode group (not shown) in which a positive electrode plate, a separator, and a negative electrode plate are laminated in this order, and an electrolyte in an enclosed container 11, and sealing the lead members 1 connected to the positive electrode plate and the negative electrode plate with a seal portion 12. In the nonaqueous electrolyte battery 10 shown in Fig. 2, the lead members 1 connected to the positive electrode plate and the lead members 1 connected to the negative electrode plate have different materials for forming the conductor foil 2. While the nonaqueous electrolyte battery 10 is sealed with the seal portion 12, the inside and outside of the battery can be electrically connected via the conductor foil 2 of the lead members 1.

[0026] The sealed container 11 may be a material that is commonly used as a packaging material for non-aqueous electrolyte batteries, and is formed, for example, from a sheet body in which resin layers are arranged on both sides of an aluminum metal foil.

[0027] The lead member 1 of the present disclosure will be described in further detail. Fig. 3 is a plan view of the lead member 1 as seen in the third direction. As shown in Fig. 3, the conductor foil 2 has a rectangular shape with one corner formed as a rounded corner portion 21 in the plan view as seen in the third direction. In this embodiment, the corner between the side surface 2c and the side surface 2e is rounded to form the rounded corner portion 21, and the first main surface 2a and the second main surface 2b each have a rectangular shape with one corner rounded.

[0028] The rounded corner portion 21 has a shape with an edge that is convex outward in a circular arc shape when viewed in a plan view from the third direction. The rounded corner portion 21 can be formed, for example, by shearing off one corner of a conductor foil whose main surface is rectangular. The length L1 along the first direction and the length L2 of the rounded corner portion 21 along the second direction may each be, for example, 0.1 mm or more and 5.0 mm or less, or 0.5 mm or more and 3.0 mm or less.

[0029] FIG. 4 is a diagram showing the side of the rounded corner portion 21, as viewed from the direction of arrow IV in FIG. 1 . The direction of arrow IV intersects, for example, with the second direction at a 45° angle. In this embodiment, the rounded corner portion 21 is formed by punching in the third direction with a cutting blade in contact with the first main surface 2a of the conductor foil. As shown in FIG. 4 , in this embodiment, the portion of the side of the rounded corner portion 21 adjacent to the first main surface 2a is the sheared surface 21a, and the portion adjacent to the second main surface 2b is the fractured surface 21b. The sheared surface 21a and the fractured surface 21b are formed on the cut surface when the corner of the rectangular conductor foil is cut to form the rounded corner portion 21. For example, by adjusting the distance between the upper and lower blades during cutting, both the sheared surface 21a and the fractured surface 21b can be formed on the cut surface. When cutting the conductor foil 2, the edge of the first main surface 2a may be pulled above the sheared surface 21a shown in FIG. 4, forming a sagging portion. Burrs protruding from the second main surface 2b in the third direction may occur below the fracture surface 21b shown in Fig. 4. Illustration of sagging and burrs is omitted in Fig. 4. The expressions "the first main surface 2a and the shear surface 21a are adjacent" and "the second main surface 2b and the fracture surface 21b are adjacent" in the above description define the positional relationship between the shear surface 21a and the fracture surface 21b, and do not exclude cases where sagging and burrs exist at the end of the conductor foil 2 in the third direction.

[0030] As mentioned above, when cutting conductor foil, burrs may occur at the cut portion. For example, if a notch is provided in the conductor foil to make it easier to distinguish between the front and back of a lead member, burrs may also occur when cutting the conductor foil to provide the notch. When welding the electrode foil connected to the lead member to the conductor foil, if the burred side of the conductor foil comes into contact with the electrode foil, the electrode foil may break. Therefore, it is desirable for the lead member to be configured so that the side with burrs and the side without burrs can be easily distinguished. Warping in the direction of the burr protrusion can also easily lead to defects such as electrode foil breakage, so it is desirable to reduce the warping of the conductor foil. To avoid these defects, it is desirable to reduce the burrs themselves.

[0031] According to the lead member 1 of this embodiment, the presence of one rounded corner makes the shape of the lead member 1 asymmetric, making it easy to distinguish between the front and back of the lead member 1. The cut corner reduces warping of the conductor foil 2. The presence of both the sheared surface 21a and the fractured surface 21b on the side of the rounded corner 21 reduces burrs compared to, for example, when only the sheared surface is present.

[0032] In this embodiment, the area ratio AR (A2 / A1) of the area A2 of the fractured surface 21b to the total area A1 of the sheared surface 21a and the fractured surface 21b will be described. The lower limit of the area ratio AR may be 0.2 or 0.3. The upper limit of the area ratio AR may be 0.5. The area ratio AR may be 0.2 or more and 0.5 or less, or 0.3 or more and 0.5 or less. The area of ​​the sheared surface 21a may be larger than the area of ​​the fractured surface 21b. When the area ratio AR is in an appropriate range, burrs are likely to be small and chipping and the like are less likely to occur when forming the rounded corner portion 21. The area ratio AR can be controlled, for example, by adjusting the gap between the upper blade and the lower blade.

[0033] In this embodiment, in a plan view seen in the third direction, the length L2 of the rounded corner portion 21 along the second direction may be longer than the length L1 of the rounded corner portion 21 along the first direction. That is, in Fig. 3, L2 may be greater than L1. When the length L2 is longer than the length L1, the influence of width variations can be reduced.

[0034] The lead member of the present disclosure will be further described below using specific examples, but the lead member of the present disclosure is not limited to these examples.

[0035] [Example 1] One corner of an aluminum conductor foil having a rectangular shape with a side of 45 mm was cut to form a rounded corner with a width of 1.5 mm and a length of 1.5 mm. Only sheared surfaces were formed on the side of the rounded corner. A burr was generated on one main surface, and the burr height was 0.02 mm.

[0036] [Example 2] One corner of an aluminum conductor foil having a rectangular shape with a 45 mm square was cut to form a rounded corner with a width of 1.5 mm and a length of 1.5 mm. Both sheared and fractured surfaces were formed on the side of the rounded corner. The ratio of the total area of ​​the sheared and fractured surfaces to the area of ​​the fractured surfaces was 0.3. Burrs were formed on the main surface adjacent to the fractured surfaces, and the height of the burrs was 0.01 mm.

[0037] [Example 3] One corner of an aluminum conductor foil having a rectangular shape with a 45 mm square was cut to form a rounded corner with a width of 1.5 mm and a length of 1.5 mm. Both sheared and fractured surfaces were formed on the side of the rounded corner. The ratio of the total area of ​​the sheared and fractured surfaces to the area of ​​the fractured surfaces was 0.2. Burrs were formed on the main surface adjacent to the fractured surface, and the height of the burrs was 0.01 mm.

[0038] A comparison with Examples 1, 2, and 3 showed that when shear surfaces and fracture surfaces are formed on the side of the rounded corner, burrs can be made smaller than when only shear surfaces are formed.

[0039] Although the lead member of the present disclosure has been described in detail above with reference to specific embodiments, the present disclosure is not limited to these embodiments.

[0040] The corner where the rounded corner is formed may be any of the four corners of the conductor foil. Of the four corners of the conductor foil, the rounded corner may be formed at a corner that is housed inside an enclosure when the conductor foil is used in a nonaqueous electrolyte battery.

[0041] REFERENCE SIGNS LIST 1 Lead member 2 Conductor foil 2a First main surface 2b Second main surface 2c, 2d, 2e, 2f Side surface 21 Rounded corner 21a Shear surface 21b Fracture surface 3 Insulating film 10 Non-aqueous electrolyte battery 11 Enclosure 12 Sealed portion

Claims

1. A lead member comprising a conductor foil and a pair of insulating films, wherein the conductor foil has a first main surface extending in a first direction and a second direction perpendicular to the first direction, and a second main surface opposite the first main surface, wherein the pair of insulating films are attached to the first main surface and a portion of the second main surface so as to straddle both side surfaces of the conductor foil along the first direction, wherein the conductor foil has a rectangular shape with one rounded corner in a plan view seen along a third direction perpendicular to the first and second directions, wherein the side surfaces of the rounded corner have a shear surface and a fracture surface, and wherein the shear surface is adjacent to the first main surface and the fracture surface is adjacent to the second main surface.

2. The lead member according to claim 1, wherein the ratio of the area of the fractured surface to the total area of the sheared surface and the fractured surface is 0.5 or less.

3. The lead member according to claim 1 or 2, wherein the ratio of the area of the fractured surface to the total area of the sheared surface and the fractured surface is 0.2 or more.

4. A lead member according to any one of claims 1 to 3, wherein the area of the shear surface is larger than the area of the fracture surface.

5. A lead member according to any one of claims 1 to 4, wherein the length of the rounded corner portion along the second direction is longer than the length of the rounded corner portion along the first direction.

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