Composite current collector and secondary battery

Abstract

The utility model provides a composite current collector and a secondary battery. The composite current collector comprises a supporting layer, and a positive electrode thin film layer and a negative electrode thin film layer which are respectively arranged on two sides of the supporting layer, the supporting layer is provided with a first tail end and a second tail end in the axial direction, the first tail end is provided with a first through hole, and the second tail end is provided with a second through hole; the positive electrode thin film layer can penetrate through the first through hole but cannot penetrate through the second through hole, and the negative electrode thin film layer can penetrate through the second through hole but cannot penetrate through the first through hole. According to the composite current collector, the production process of the tab can be simplified, and the mechanical strength of the tab is improved, so that the safety performance and the space utilization rate of the battery can be integrally improved.

Description

Technical Field

[0001] The present application relates to the technical field of lithium ion batteries, and in particular to a composite current collector and a secondary battery for lithium ions. Background Art

[0002] As an important part of electric vehicles, the safety and reliability of secondary batteries are particularly important. The puncture test of secondary batteries is generally risky, so composite current collectors have been developed in the industry. However, conventional composite current collectors usually coat two layers of metal films on the insulating film, and on this basis, the metals on both sides of the insulating film are welded together with their respective thin metals by welding (such as roll welding), and then the metal films on both sides are connected; however, welding will increase the thickness of the composite current collector at the welding point, and the welding point is not easy to bend, which affects the connection stability; and the two ends of the composite current collector need to be welded with new metal film layers to form the positive electrode ear and the negative electrode ear, which increases the thickness of the two ends of the composite current collector and reduces the space utilization rate. Utility Model Content

[0003] In order to solve the technical problems of complex production process of pole ears and low space utilization in the composite current collector in the prior art, the utility model provides a composite current collector, including: a support layer, and a positive electrode thin film layer and a negative electrode thin film layer respectively arranged on both sides of the support layer; the support layer is provided with a first end and a second end in the axial direction, the first end is provided with a first through hole, and the second end is provided with a second through hole; the positive electrode thin film layer can pass through the first through hole but not through the second through hole, and the negative electrode thin film layer can pass through the second through hole but not through the first through hole.

[0004] Furthermore, the composite current collector includes a main body, a first end, and a second end. The first end of the composite current collector can be formed as a positive electrode tab, and the second end of the composite current collector can be formed as a negative electrode tab.

[0005] Furthermore, a plurality of the first through holes are provided, and a plurality of the second through holes are also provided.

[0006] Further, the plurality of first through holes are formed into two rows, and the two rows of first through holes are symmetrically arranged.

[0007] Further, the first through hole is formed within a range of 50 mm from the end of the supporting layer.

[0008] Furthermore, the through hole is rectangular.

[0009] Furthermore, the support layer is made of insulating material.

[0010] Furthermore, the positive electrode thin film layer is made of aluminum, and the negative electrode thin film layer is made of copper.

[0011] Furthermore, the thickness of the support layer is 2-4 μm.

[0012] Another aspect of the utility model provides a secondary battery having the composite current collector.

[0013] In the composite current collector of the utility model, the positive electrode film layer and the negative electrode film layer can be connected to the support layer material by chemical plating or electrodeposition to form a sandwich structure. The middle support layer is made of insulating material, which can be used to support the positive electrode film layer and the negative electrode film layer to play a role of mechanical reinforcement and improve the mechanical strength of the composite current collector. At the same time, at the first end and the second end of the composite current collector, the positive electrode film layer and the negative electrode film layer can pass through the first through hole and the second through hole in the support layer respectively, so that the positive electrode tab and the negative electrode tab can be formed integrally at the two ends of the composite current collector. Therefore, the composite current collector of the utility model can simplify the tab production process and improve the mechanical strength of the tab, thereby improving the battery safety performance and space utilization as a whole. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of the composite current collector of the utility model from a first angle;

[0015] Figure 2 A schematic diagram of a composite current collector of the utility model from a second angle;

[0016] Figure 3 It is a schematic diagram of the decomposition of the composite current collector of the utility model;

[0017] Figure 4 It is a schematic diagram of the support layer in the composite current collector of the utility model. DETAILED DESCRIPTION

[0018] The specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the present invention, and is not used to limit the present invention.

[0019] like Figure 1-4 As shown, the composite current collector 10 provided by the present invention includes a support layer 102 and a positive electrode thin film layer 101 and a negative electrode thin film layer 103 respectively arranged on both sides of the support layer 102. Figure 1As shown, the composite current collector 10 of the utility model has a first end 11 and a second end 12 in the axial direction and a main body 13 arranged between the first end 11 and the second end 12; the main body 13 is used to support the positive and negative active materials. Specifically, the support layer 102 includes a first end 1023 and a second end 1024 and a main body 1025 arranged between the first end 1023 and the second end 1024. The first end 1023 of the support layer 102 is provided with a first through hole 1021; the second end 1024 of the support layer 102 is provided with a second through hole 1022. In this embodiment, there are 4 first through holes 1021 of the first end 1023, and 4 second through holes 1022 of the second end 1024 are also provided; the four first through holes 1021 of the first end 1023 are formed in two rows in the front-to-back direction, and each row is provided with 2, and the first through holes 1021 of the front and back rows are symmetrically arranged. In this embodiment, the first through hole 1021 is formed into a rectangle. Of course, optionally, the first through hole 1021 can also be configured as a circle or other shapes. The number of the first through holes 1021 is also not limited. When the area of ​​the composite current collector formed is large, the number of the first through holes can be set to more, as long as it can achieve that the metal of the positive electrode thin film layer can pass through the first through hole and ensure the conductivity and mechanical strength of the first end. The composite current collector of this embodiment is provided with a first end portion of the first through hole and a second end provided with a second through hole. In the subsequent battery production process, the positive electrode active material will not be coated, and the main body provided between the first end and the second end will be coated with a negative electrode active material in the subsequent battery production process. Therefore, the first end of the composite current collector of the utility model can be used as a positive electrode tab during the battery production process, or it can be connected to an external conductive structure to conduct electricity to form a positive electrode tab. Preferably, in this embodiment, the first end provided with the first through hole 1021 is formed at the left end of the supporting main body 1025, and in the axial direction, it is located in the area of ​​the main body 1025 with a distance DD, and D is preferably set to be less than or equal to 50mm. The distance of the first through hole 1021 in the axial direction is set to be less than or equal to 50 mm, which can ensure that the area can be used as a conductive tab in the future without affecting the overall performance of the composite current collector.

[0020] In this embodiment, the support layer 102 is preferably made of a high molecular polymer, preferably with a thickness of 2-4 μm, usually an insulating material such as PP, PET, etc. The positive electrode film layer 101 is connected to the support layer 102 by electroplating, electrodeposition, etc. In this embodiment, the support layer 102 provides a skeleton support function, which plays a decisive role in the physical and mechanical properties such as tensile strength and elongation of the composite current collector 10. The positive electrode film layer 101 is formed on the support layer 102, and the negative electrode film layer is formed below the support layer 102. The positive electrode film layer 101 and the negative electrode film layer 102 play a current collection role, which is the main part of the composite current collector, and determines the conductive properties of the composite current collector. When the positive electrode film layer of the composite current collector of the utility model is preferably made of aluminum material; the negative electrode film layer is preferably made of copper material. Of course, optionally, the materials of the positive electrode film layer and the negative electrode film layer are not limited, as long as they can realize the normal function in the battery, so they can also be formed as other metal materials or conductive materials. In order to improve the space utilization of the composite current collector, the utility model preferably sets the thickness of the positive electrode film layer in the range of 0.5-3μm to ensure that the composite current collector has good conductivity without increasing the thickness of the composite current collector, thereby improving the space utilization of the composite current collector in the battery.

[0021] like Figure 1-3As shown, at the first end 11 of the composite current collector of the present invention, the positive electrode thin film layer 101 can pass through the first through hole 1021 of the support layer 102 but will not pass through the second through hole 1022 of the support layer, and the negative electrode thin film layer 103 can pass through the second through hole 1022 but will not pass through the first through hole 1021. At the same time, in the first end 11 of the current collector 10, the first through hole 1021 and the support layer material 102 are arranged at intervals, and the arrangement of multiple first through holes 1021 can increase the contact area between the positive electrode thin film layer 101 and the support layer 102, and improve the contact stability between the positive electrode thin film layer 101 and the support layer. The arrangement of the support layer 102 at the first end 102 can increase the mechanical properties and support strength of the first end of the composite current collector compared to the arrangement of only the positive electrode thin film layer without the support layer. In this embodiment, the first end is provided with a first through hole, and the ratio of the area occupied by the first through hole 1021 to the area occupied by the supporting material is preferably 1 / 3-1 / 2. Such a setting can ensure both good conductivity and excellent mechanical properties of the composite current collector end. The structure of the second end 12 of the composite current collector is similar to that of the first end, except that the second end 12 is provided with a second through hole 1024 through which the negative electrode film layer 103 passes through the supporting layer, but the positive electrode film 101 does not pass through the second through hole 1024 of the supporting layer. The other structures are the same as the first end structure, and will not be repeated again. Therefore, the first end of the composite current collector of the utility model is only provided with a positive electrode film layer, and the second end is only provided with a negative electrode film layer. In the subsequent production process of the composite current collector for battery pole pieces, the first end will not be coated with a positive electrode material so that the first end can be used to form a positive electrode tab; the second end will not be coated with a negative electrode material so that the second end can be used to form a negative electrode tab.

[0022] In the composite current collector of the utility model, the positive electrode film layer and the negative electrode film layer can be connected to the support layer material by chemical plating or electrodeposition to form a sandwich structure. The middle support layer is made of insulating material, which can be used to support the positive electrode film layer and the negative electrode film layer to play a role of mechanical reinforcement and improve the mechanical strength of the composite current collector. At the same time, at the first end and the second end of the composite current collector, the positive electrode film layer and the negative electrode film layer can pass through the first through hole and the second through hole in the support layer respectively, so that the positive electrode tab and the negative electrode tab can be formed integrally at the two ends of the composite current collector. Therefore, the composite current collector of the utility model can simplify the tab production process and improve the mechanical strength of the tab, thereby improving the battery safety performance and space utilization as a whole.

[0023] Obviously, the above embodiments of the present invention are only examples for the purpose of clearly explaining the present invention.

[0024] It is not a limitation of the implementation methods of the utility model. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made on the basis of the above description. It is not necessary and impossible to list all the implementation methods here. Any modification, equivalent replacement and improvement made within the spirit and principle of the utility model should be included in the protection scope of the claims of the utility model.

Claims

1. A composite current collector, characterized in that: include: A support layer, and a positive electrode thin film layer and a negative electrode thin film layer respectively arranged on both sides of the support layer; The support layer is provided with a first end and a second end in the axial direction, the first end is provided with a first through hole, and the second end is provided with a second through hole; the positive electrode film layer can pass through the first through hole but not through the second through hole, and the negative electrode film layer can pass through the second through hole but not through the first through hole.

2. The composite current collector according to claim 1, characterized in that: The composite current collector includes a main body, a first end, and a second end. The first end of the composite current collector can be formed as a positive electrode tab, and the second end of the composite current collector can be formed as a negative electrode tab.

3. The composite current collector according to claim 1, characterized in that: A plurality of the first through holes are provided, and a plurality of the second through holes are also provided.

4. The composite current collector according to claim 2, characterized in that: The plurality of first through holes are formed in two rows, and the two rows of first through holes are symmetrically arranged.

5. The composite current collector according to claim 1, characterized in that: The first through hole is formed within a range of 50 mm from an end of the supporting layer.

6. The composite current collector according to claim 1, characterized in that: The through hole is rectangular.

7. The composite current collector according to claim 1, characterized in that: The supporting layer is made of insulating material.

8. The composite current collector according to claim 1, characterized in that: The positive electrode thin film layer is made of aluminum, and the negative electrode thin film layer is made of copper.

9. The composite current collector according to claim 1, characterized in that: The thickness of the support layer is 2-4 μm.

10. A secondary battery, characterized in that: It comprises a composite current collector as described in any one of claims 1 to 9.

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