Current collector and battery

Abstract

This prevents the conductive layer from peeling off from the support layer. [Solution] The current collector 100A comprises a support layer 110, a conductive layer 120, and an intermediate conductive layer 130. The support layer 110 is made of an electrically insulating resin composition. The conductive layer 120 is made of a metal containing aluminum. The intermediate conductive layer 130 is made of a metal containing magnesium. The conductive layer 120 is joined to the support layer 110 via the intermediate conductive layer 130.

Description

Technical Field

[0001] The present disclosure relates to a current collector and a battery.

Background Art

[0002] JP-T 2024-510696 discloses a conventional electrode plate. The electrode plate includes a current collector, an active material layer, and an electrical connection member. The current collector includes a support layer and a conductive layer. The support layer is a polyethylene film, a polypropylene film, a polyvinylidene chloride film, or a multilayer composite film thereof. The conductive layer is provided on one surface of the support layer. When the current collector is a positive current collector, aluminum is usually used as the material of the conductive layer, and when the current collector is a negative current collector, copper is usually used as the material of the conductive layer.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] For example, when the conductive layer containing aluminum is made thin and the conductive layer is provided on the support layer by a vapor deposition method or a sputtering method, the adhesive force between the conductive layer and the support layer is relatively weak. Thus, there is room for further improvement in suppressing the peeling between the conductive layer and the support layer.

[0005] The present disclosure has been made in view of the above problems, and an object thereof is to provide a current collector and a battery capable of suppressing peeling of the conductive layer from the support layer.

Means for Solving the Problems

[0006] A current collector according to a certain aspect of the present disclosure comprises a support layer, a conductive layer, and an intermediate conductive layer. The support layer is made of an electrically insulating resin composition. The conductive layer is made of a metal containing aluminum. The intermediate conductive layer is made of a metal containing magnesium. The conductive layer is bonded to the support layer via the intermediate conductive layer.

[0007] A battery according to a certain aspect of this disclosure comprises an electrode body and an external terminal. The electrode body includes a first electrode, a second electrode, and a separator. The first electrode includes a current collector and an active material layer. The current collector includes a support layer, a conductive layer, and an intermediate conductive layer. The support layer is made of an electrically insulating resin composition. The conductive layer is made of a metal containing aluminum. The intermediate conductive layer is made of a metal containing magnesium. The conductive layer is bonded to the support layer via the intermediate conductive layer. The active material layer is laminated on the conductive layer. The separator is laminated on the active material layer. The second electrode is laminated on the active material layer via the separator. The external terminal is electrically connected to the conductive layer. [Effects of the Invention]

[0008] According to this disclosure, it is possible to suppress the delamination of the conductive layer from the support layer. [Brief explanation of the drawing]

[0009] [Figure 1] This is a cross-sectional view showing a battery according to one embodiment. [Figure 2] This is a cross-sectional view of the electrode body in Figure 1, taken in the direction of the arrow line II-II. [Figure 3] This is an exploded view of the first electrode in one embodiment. [Figure 4] This is a partial cross-sectional view of the first electrode in Figure 3, viewed in the direction of the IV-IV line arrow. [Modes for carrying out the invention]

[0010] Hereinafter, a current collector and a battery according to one embodiment of the present disclosure will be described with reference to the drawings. The same or corresponding parts in the drawings are denoted by the same reference numerals, and their descriptions will not be repeated.

[0011] Figure 1 is a cross-sectional view showing a battery according to one embodiment. The battery 1 shown in Figure 1 is a so-called prismatic battery. Battery 1 may be a rechargeable secondary battery such as a lithium-ion battery or a nickel-metal hydride battery. Battery 1 can be used, for example, as a cell included in an energy storage module mounted on an electric vehicle.

[0012] As shown in Figure 1, a battery 1 according to one embodiment of the present disclosure comprises an electrode body 10, a case 20, a first external terminal 30A, a second external terminal 30B, a first connecting member 40A, and a second connecting member 40B. First, the components of the battery 1 other than the electrode body 10 will be described.

[0013] Case 20 is conductive. The conductive portion of Case 20 is made of a metal such as aluminum. Case 20 houses the electrode body 10. Case 20 also houses an electrolyte solution, which is not shown in the diagram.

[0014] Case 20 includes a case body 21 and a lid 22. The case body 21 includes a bottom wall 21a and a peripheral wall 21b that rises from the bottom wall 21a.

[0015] The lid 22 is joined to the peripheral wall 21b by welding or other means so as to close the opening in the peripheral wall 21b. The lid 22 has a first connecting hole 22a and a second connecting hole 22b formed therein.

[0016] The first external terminal 30A and the second external terminal 30B are provided so as to be exposed to the outside in the battery 1. The first connecting member 40A and the second connecting member 40B are conductive. At least a portion of the first connecting member 40A and the second connecting member 40B are located inside the case 20.

[0017] The first external terminal 30A or the first connecting member 40A is inserted into the first connecting hole 22a. The first external terminal 30A is electrically connected to the first connecting member 40A. Specifically, the first external terminal 30A and the first connecting member 40A are joined to each other. The first connecting member 40A is joined to the electrode body 10. Thereby, the first external terminal 30A is electrically connected to the electrode body 10.

[0018] The second external terminal 30B or the second connecting member 40B is inserted into the second connecting hole 22b. The second external terminal 30B is electrically connected to the second connecting member 40B. Specifically, the second external terminal 30B and the second connecting member 40B are joined to each other. The second connecting member 40B is joined to the electrode body 10. Thereby, the second external terminal 30B is electrically connected to the electrode body 10.

[0019] In this embodiment, the first external terminal 30A is the positive terminal, and the second external terminal 30B is the negative terminal. The first external terminal 30A and the second external terminal 30B are arranged side by side in the second direction D2. The second direction D2 is a direction perpendicular to the first direction D1.

[0020] Next, the electrode body 10 will be described. The battery 1 according to this embodiment includes a plurality of electrode bodies 10. The battery 1 typically includes two electrode bodies 10. These electrode bodies 10 are arranged side by side in the third direction D3. The third direction D3 is a direction perpendicular to both the first direction D1 and the second direction D2.

[0021] In the following, one electrode body 10 out of the plurality of electrode bodies 10 will be described. Note that each of the plurality of electrode bodies 10 may have the configuration shown below.

[0022] FIG. 2 is a cross-sectional view of the electrode body of FIG. 1 as viewed in the direction of the arrow of line II-II. As shown in FIGS. 1 and 2, the electrode body 10 includes a first electrode 11A, a second electrode 11B, and a separator 12. The electrode body 10 is wound such that the first electrode 11A, the second electrode 11B, and the separator 12 surround the winding axis Z. Thus, in the present embodiment, the electrode body 10 is a so-called wound electrode body. However, the electrode body 10 may be a laminated electrode body in which the first electrode 11A, the second electrode 11B, and the separator 12 are laminated in one direction (for example, the third direction D3). In FIG. 2, the separator 12 is schematically shown by a broken line.

[0023] The first electrode 11A and the second electrode 11B have a sheet-like outer shape. The electrode body 10 is composed of a group of electrode plates in which the first electrode 11A and the second electrode 11B are wound via one or more separators 12. In the present embodiment, the first electrode 11A is the positive electrode and the second electrode 11B is the negative electrode. However, the first electrode 11A may be the negative electrode and the second electrode 11B may be the positive electrode.

[0024] The separator 12 is provided between the first electrode 11A and the second electrode 11B. The separator 12 separates the first electrode 11A and the second electrode 11B while allowing the passage of ions between the first electrode 11A and the second electrode 11B. The ions are, for example, lithium ions. The separator 12 has electrical insulation.

[0025] FIG. 3 is a developed view of the first electrode in an embodiment. That is, FIG. 3 shows the state before the first electrode 11A is wound. FIG. 4 is a partial cross-sectional view of the first electrode of FIG. 3 as viewed in the direction of the arrow of line IV-IV.

[0026] As shown in FIGS. 2 to 4, the first electrode 11A includes a first current collector 100A, a pair of first active material layers 200A, a first protection part 400, and a second protection part 500.

[0027] As shown in Figure 4, the first current collector 100A includes a support layer 110, a first conductive layer 120, a first intermediate conductive layer 130, a second conductive layer 140, a second intermediate conductive layer 150, a plurality of tab portions 160, and a plurality of conductive auxiliary portions 170.

[0028] The support layer 110 is made of an electrically insulating resin composition. Therefore, the first current collector 100A is a composite current collector made of a conductive material and an electrically insulating material. As a result, the first current collector 100A is lighter and the overall safety of the battery 1 is improved compared to when the first current collector 100A is made entirely of metal.

[0029] Furthermore, the support layer 110 is made of a material with higher rigidity than the separator 12. The support layer 110 is made of a resin composition containing, for example, a polyamide resin, a polyester resin, or a polyolefin resin. To increase rigidity, it is preferable that the support layer 110 is made of a resin composition containing a polyester resin. It is even more preferable that the support layer 110 is substantially made of a polyester resin. The polyester resin may be, for example, polyethylene terephthalate (PET). This makes it possible to increase the rigidity of the first current collector 100A while maintaining the electrical insulation properties of the support layer 110. Consequently, the support layer 110 can be made relatively thin.

[0030] The thickness direction DT of the support layer 110 is approximately perpendicular to the first direction D1. That is, the support layer 110 extends in a direction approximately perpendicular to the first direction D1.

[0031] The overall thickness of the support layer 110 is preferably 20 μm or less, more preferably 15 μm or less, and even more preferably 10 μm or less, in order to reduce the overall thickness of the electrode body 10. The overall thickness of the support layer 110 is not particularly limited as long as it has the desired rigidity. The thickness of the support layer 110 may be, for example, 2 μm or more.

[0032] The support layer 110 includes a main body portion 111 and an extension portion 112. The main body portion 111 is laminated between the first intermediate conductive layer 130 and the second intermediate conductive layer 150. The extension portion 112 extends from the main body portion 111 in a direction perpendicular to the thickness direction DT. The extension portion 112 is separated from the first intermediate conductive layer 130 and the second intermediate conductive layer 150 and is not joined to the first intermediate conductive layer 130 and the second intermediate conductive layer 150. The extension portion 112 is joined to a part of the first conductive layer 120 and a part of the second conductive layer 140.

[0033] The first conductive layer 120 is made of a metal containing aluminum. This allows the first current collector 100A, equipped with the first conductive layer 120, to be suitably used as a positive electrode current collector. The first conductive layer 120 may be composed substantially of aluminum alone. The first current collector 100A may also be a negative electrode current collector.

[0034] The first conductive layer 120 is located on one side of the support layer 110 in the thickness direction DT. The first conductive layer 120 is bonded to the support layer 110 via the first intermediate conductive layer 130. The first conductive layer 120 includes a first conductive main body portion 121 and a first conductive extension portion 122. The first conductive main body portion 121 is bonded to the first intermediate conductive layer 130. The first conductive extension portion 122 extends from the first conductive main body portion 121. The first conductive extension portion 122 is bonded to the extension portion 112. The first conductive extension portion 122 is not bonded to the first intermediate conductive layer 130.

[0035] The first intermediate conductive layer 130 is made of a metal containing magnesium. As a result, when the support layer 110 is made of a resin composition containing a polyester resin (particularly PET), the magnesium in the first intermediate conductive layer 130 and the oxygen atoms contained in the polyester resin of the support layer 110 readily bond to each other. This results in an even stronger bond between the first intermediate conductive layer 130 and the support layer 110. Consequently, the peeling of the first conductive layer 120 connected to the first intermediate conductive layer 130 from the support layer 110 is further suppressed.

[0036] The first intermediate conductive layer 130 may be an alloy containing a metal other than magnesium. This alloy may contain at least one selected from the group consisting of copper, nickel, tin, aluminum, zinc, iron, manganese, cobalt, and titanium.

[0037] The second conductive layer 140 is located on the other side of the support layer 110 in the thickness direction DT. The second conductive layer 140 is made of a metal containing aluminum. The second conductive layer 140 may be made substantially of aluminum alone.

[0038] The second conductive layer 140 is bonded to the support layer 110 via the second intermediate conductive layer 150. The second conductive layer 140 includes a second conductive main body 141 and a second conductive extension 142. The second conductive main body 141 is bonded to the second intermediate conductive layer 150. The second conductive extension 142 extends from the second conductive main body 141. The second conductive extension 142 is bonded to the extension 112. The second conductive extension 142 is not bonded to the second intermediate conductive layer 150.

[0039] The second intermediate conductive layer 150 is made of a metal containing magnesium. Therefore, when the support layer 110 is made of a resin composition containing a polyester resin (particularly PET), the magnesium in the second intermediate conductive layer 150 and the oxygen atoms in the polyester resin of the support layer 110 readily bond to each other. This results in an even stronger bond between the second intermediate conductive layer 150 and the support layer 110. Consequently, the peeling of the second conductive layer 140 connected to the second intermediate conductive layer 150 from the support layer 110 is further suppressed.

[0040] The second intermediate conductive layer 150 may be an alloy containing a metal other than magnesium. This alloy may contain at least one selected from the group consisting of copper, nickel, tin, aluminum, zinc, iron, manganese, cobalt, and titanium.

[0041] The thickness of each of the first conductive layer 120, the first intermediate conductive layer 130, the second conductive layer 140, and the second intermediate conductive layer 150 is thinner than the thickness of the support layer 110. The thickness of each of the first intermediate conductive layer 130, the second conductive layer 140, and the second intermediate conductive layer 150 is, for example, 5 μm or less, more preferably 2 μm or less, and even more preferably 1 μm or less, in order to reduce the overall thickness of the electrode body 10. The thickness of each of the first intermediate conductive layer 130, the second conductive layer 140, and the second intermediate conductive layer 150 may be, for example, 0.1 μm or more, in order to prevent their electrical resistance from becoming too large. Note that if the thickness of the first conductive layer 120 and the second conductive layer 140 are 5 μm or less, it is difficult to directly weld the first conductive layer 120 and the second conductive layer 140 to each other or to directly join them to each other by ultrasonic welding.

[0042] The method for forming the first conductive layer 120, the first intermediate conductive layer 130, the second conductive layer 140, and the second intermediate conductive layer 150 is not particularly limited. These layers may typically be formed by vapor deposition or sputtering.

[0043] As shown in Figure 3, the multiple tab portions 160 are aligned in the winding direction DR of the electrode body 10. The multiple conductive auxiliary portions 170 are aligned in the winding direction DR of the electrode body 10. The multiple tab portions 160 are spaced apart from each other. The multiple conductive auxiliary portions 170 are spaced apart from each other. The multiple conductive auxiliary portions 170 are aligned with the multiple tab portions 160 in a one-to-one correspondence in the thickness direction DT.

[0044] As shown in Figure 2, the multiple tab portions 160 are arranged in the third direction D3. The multiple tab portions 160 are joined to each other by ultrasonic bonding or the like. Furthermore, as shown in Figure 1, the multiple tab portions 160 are joined to the first connecting member 40A by ultrasonic bonding or the like. As a result, the first external terminal 30A is electrically connected to the tab portion 160. Consequently, the first external terminal 30A is electrically connected to the first conductive layer 120 and the second conductive layer 140. The configurations of each of the multiple tab portions 160 and each of the multiple conductive auxiliary portions 170 will be described below.

[0045] As shown in Figure 4, the tab portion 160 is partially aligned in the thickness direction DT with the first conductive extension portion 122 and the first conductive body portion 121. The tab portion 160 extends approximately along the first direction D1 on the first conductive layer 120. The tab portion 160 is joined to the first conductive extension portion 122 by ultrasonic welding. The tab portion 160 is joined to a portion of the first conductive body portion 121 by ultrasonic welding. The tab portion 160 extends away from the first conductive layer 120. The extension direction DE of the tab portion 160 is approximately parallel to the first direction D1. The tab portion 160 may also be directly joined to the first external terminal 30A.

[0046] The conductive auxiliary portion 170 is partially aligned in the thickness direction DT with the second conductive extension portion 142 and the second conductive main body portion 141. The conductive auxiliary portion 170 extends approximately along the first direction D1 on the second conductive layer 140. The conductive auxiliary portion 170 is joined to the second conductive extension portion 142 by ultrasonic welding. The conductive auxiliary portion 170 is joined to a portion of the second conductive main body portion 141 by ultrasonic welding. The conductive auxiliary portion 170 extends away from the second conductive layer 140. The end of the conductive auxiliary portion 170 in the extension direction DE is joined to the tab portion 160 by ultrasonic welding.

[0047] The tab portion 160 and the conductive auxiliary portion 170 are made of a film-like material. Typically, the tab portion 160 and the conductive auxiliary portion 170 are made of a metal film containing aluminum or copper.

[0048] The thickness of the tab portion 160 and the conductive auxiliary portion 170 is greater than the thickness of the first conductive layer 120, the first intermediate conductive layer 130, the second conductive layer 140, and the second intermediate conductive layer 150. The thickness of the tab portion 160 and the conductive auxiliary portion 170 is preferably 20 μm or less, more preferably 15 μm or less, and even more preferably 10 μm or less. The thickness of each of these is not particularly limited as long as it has the desired rigidity. The thickness of each of these may be, for example, 2 μm or more.

[0049] One of the first active material layers 200A is laminated on the first conductive layer 120. Specifically, one of the first active material layers 200A is laminated on a portion of the first conductive main body 121. The other of the first active material layers 200A is not laminated on the first conductive extension 122. That is, the first active material layer 200A is not laminated at the connection portion between the first conductive extension 122 and the first conductive main body 121. As a result, when the first active material layer 200A is pressed against the first conductive layer 120 by, for example, a press roll, the pressure applied to the first active material layer 200A becomes relatively uniform. Furthermore, one of the first active material layers 200A is not laminated on the end of the first conductive main body 121 on the DE side in the extension direction.

[0050] The other first active material layer 200A is laminated on the second conductive layer 140. Specifically, the other first active material layer 200A is laminated on a portion of the second conductive main body 141. The other first active material layer 200A is not laminated on the second conductive extension 142. The other first active material layer 200A is also not laminated on the end of the second conductive main body 141 on the extension direction DE side.

[0051] These first active material layers 200A are positive electrode active material layers, but may also be negative electrode active material layers. These first active material layers 200A are separated from the tab portion 160 and the conductive auxiliary portion 170. The separator 12 is laminated on the first active material layers 200A in the radial direction centered on the winding axis Z.

[0052] The first protective portion 400 is made of an electrically insulating ceramic. The first protective portion 400 covers a portion of the first active material layer 200A laminated on the first conductive layer 120 on the extension direction DE side. The first protective portion 400 covers the entire surface of the first conductive layer 120 (first conductive main body portion 121) between the first active material layer 200A and the tab portion 160. The first protective portion 400 is also partially positioned between the first conductive layer 120 (first conductive main body portion 121) and the tab portion 160 in the thickness direction DT.

[0053] The second protective portion 500 is made of an electrically insulating ceramic. The second protective portion 500 covers a portion of the first active material layer 200A, which is laminated on the second conductive layer 140, on the extension direction DE side. The second protective portion 500 covers the entire surface of the second conductive layer 140 (second conductive main body portion 141) between the first active material layer 200A and the conductive auxiliary portion 170. The second protective portion 500 is also partially positioned between the second conductive layer 140 (second conductive main body portion 141) and the conductive auxiliary portion 170 in the thickness direction DT.

[0054] As shown in Figure 2, the second electrode 11B is laminated on the first active material layer 200A via a separator 12 in the radial direction. In this embodiment, the electrode body 10 includes multiple separators 12, but it may also include a single separator 12.

[0055] The second electrode 11B includes a second current collector 100B and a second active material layer 200B. The second current collector 100B is drawn out from between the second active material layers 200B to one side in the first direction D1. The second current collector 100B is joined to the second connecting member 40B by ultrasonic welding (see Figure 1).

[0056] The second current collector 100B is made of, for example, a metal film. The second current collector 100B is made of, for example, a metal containing copper. This allows the second current collector 100B to be suitably used as a negative electrode current collector. In the case where the first current collector 100A is a negative electrode current collector and the second current collector 100B is a positive electrode current collector, the second current collector 100B may be made of a metal containing aluminum. Furthermore, the second current collector 100B may have the same configuration as the first current collector 100A.

[0057] The second active material layer 200B is laminated on both sides of the second current collector 100B. In this embodiment, the second electrode 11B is the negative electrode. Therefore, the second active material layer 200B is the negative electrode active material layer. The second active material layer 200B may also be the positive electrode active material layer.

[0058] As described above, a first current collector 100A according to one embodiment of the present disclosure comprises a support layer 110, a first conductive layer 120, and a first intermediate conductive layer 130. The support layer 110 is made of an electrically insulating resin composition. The first conductive layer 120 is made of a metal containing aluminum. The first intermediate conductive layer 130 is made of a metal containing magnesium. The first conductive layer 120 is bonded to the support layer 110 via the first intermediate conductive layer 130.

[0059] With the above configuration, the surface of the first current collector 100A is made of aluminum, while the first intermediate conductive layer 130 containing magnesium improves the overall strength of the conductive layer, from the viewpoint of providing the first active material layer 200A on the first conductive layer 120. Therefore, peeling of the first conductive layer 120 from the support layer 110 can be suppressed.

[0060] The first current collector 100A further comprises a tab portion 160. The support layer 110 includes a main body portion 111 and an extension portion 112. The main body portion 111 is joined to the first intermediate conductive layer 130. The extension portion 112 extends from the main body portion 111. The first conductive layer 120 includes a first conductive main body portion 121 and a first conductive extension portion 122. The first conductive main body portion 121 is joined to the first intermediate conductive layer 130. The first conductive extension portion 122 extends from the first conductive main body portion 121 and is joined to the extension portion 112. The tab portion 160 is joined to the first conductive extension portion 122 by ultrasonic welding.

[0061] According to the above configuration, the number of interfaces between layers can be reduced in the direction in which the tab portion 160 and the first conductive extension portion 122 are aligned. Therefore, the mechanical bonding strength in ultrasonic welding of the tab portion 160 and the first conductive extension portion 122 can be improved.

[0062] The tab portion 160 is joined to the first conductive main body portion 121 by ultrasonic welding. This allows the tab portion 160 to mechanically prevent the connection portion between the first conductive main body portion 121 and the first conductive extension portion 122 from separating from the end of the first intermediate conductive layer 130.

[0063] Furthermore, in this embodiment, the first active material layer 200A is laminated on the first conductive body portion 121. As a result, the first active material layer 200A is laminated on the first conductive body portion 121 which is laminated on the first intermediate conductive layer 130, thereby suppressing the peeling of the first active material layer 200A from the support layer 110 together with the first conductive layer 120.

[0064] Furthermore, in this embodiment, the first active material layer 200A is separated from the tab portion 160. Here, since the tab portion 160 is also joined to the first conductive body portion 121, the current path from the first active material layer 200A to the tab portion 160, or from the tab portion 160 to the first active material layer 200A, is formed not only by the first conductive body portion 121 but also by the first intermediate conductive layer 130. This makes it possible to reduce the electrical resistance of the current path from the first active material layer 200A to the tab portion 160, or from the tab portion 160 to the first active material layer 200A.

[0065] In the above-described embodiment, the combinatable configurations may be combined with each other.

[0066] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of this disclosure is indicated by the claims rather than the foregoing description, and all modifications within the meaning and scope equivalent to the claims are intended. [Explanation of Symbols]

[0067] 1 Battery, 10 Electrode body, 11A First electrode, 11B Second electrode, 12 Separator, 20 Case, 21 Case body, 21a Bottom wall, 21b Peripheral wall, 22 Lid, 22a First connecting hole, 22b Second connecting hole, 30A First external terminal, 30B Second external terminal, 40A First connecting member, 40B Second connecting member, 100A First current collector, 100B Second current collector, 110 Support layer, 111 Main body, 112 Extension, 120 First conductive layer, 121 First conductive main body, 122 First conductive extension, 130 First intermediate conductive layer, 140 Second conductive layer, 141 Second conductive main body, 142 Second conductive extension, 150 Second intermediate conductive layer, 160 Tab, 170 Conductive auxiliary part, 200A First active material layer, 200B; Second active material layer, 400; First protective section, 500; Second protective section, D1 first direction, D2 second direction, D3 third direction, DE extension direction, DR winding direction, DT thickness direction, Z winding axis.

Claims

1. It is a current collector, Supporting layer, A conductive layer, It comprises an intermediate conductive layer, The support layer is made of an electrically insulating resin composition. The conductive layer is made of a metal containing aluminum, The aforementioned intermediate conductive layer is made of a metal containing magnesium, A current collector wherein the conductive layer is joined to the support layer via the intermediate conductive layer.

2. It also has a tab section, The support layer includes a main body and an extension, The main body is bonded to the intermediate conductive layer, The extension extends from the main body, The conductive layer includes a conductive main body and a conductive extension. The conductive main body is bonded to the intermediate conductive layer, The conductive extension extends from the conductive main body and is joined to the extension. The current collector according to claim 1, wherein the tab portion is joined to the conductive extension portion by ultrasonic welding.

3. The current collector according to claim 2, wherein the tab portion is joined to the conductive main body portion by ultrasonic welding.

4. It is a battery, Electrode body and Equipped with external terminals, The electrode body includes a first electrode, a second electrode, and a separator. The first electrode comprises a current collector and an active material layer. The current collector includes a support layer, a conductive layer, and an intermediate conductive layer. The support layer is made of an electrically insulating resin composition. The conductive layer is made of a metal containing aluminum, The aforementioned intermediate conductive layer is made of a metal containing magnesium, The conductive layer is bonded to the support layer via the intermediate conductive layer. The active material layer is laminated on the conductive layer, The separator is laminated on the active material layer, The second electrode is laminated on the active material layer via the separator, The external terminal is electrically connected to the conductive layer, and is a battery.

5. The current collector further includes a tab portion, The support layer includes a main body and an extension, The main body is bonded to the intermediate conductive layer, The extension extends from the main body, The conductive layer includes a conductive main body and a conductive extension. The conductive main body is bonded to the intermediate conductive layer, The conductive extension extends from the conductive main body and is joined to the extension. The tab portion is joined to the conductive extension portion by ultrasonic welding. The tab portion is joined to the conductive main body portion by ultrasonic welding. The active material layer is laminated on the conductive main body, The active material layer is separated from the tab portion. The battery according to claim 4, wherein the external terminal is electrically connected to the tab portion.

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