Composite copper foil with locally enhanced solder region

Abstract

The utility model relates to lithium battery material technical field, and concretely relates to a kind of composite copper foil with local reinforcement welding area, including composite copper foil body, predetermined welding area of the composite copper foil body is provided with through-hole, predetermined welding area of the composite copper foil body is provided with metal foil to be welded with tab, the metal foil covers the through-hole.In the technical scheme provided in the utility model, the through-hole provides effective escape channel for gas generated in the welding process, fundamentally eliminates the phenomenon of bubbling and false welding, by metal foil, under the premise of not significantly changing the overall thickness and weight of current collector, selectively and accurately reduce the square resistance of welding area by about 40%, which effectively reduces the overall internal resistance of battery and welding point heat production, so that the battery has better fast charging and fast discharging capacity, and reduces the performance decay in the cycle process.

Description

Technical Field

[0001] This utility model relates to the field of lithium battery material technology, and specifically to a composite copper foil with a locally reinforced welding zone. Background Technology

[0002] Composite current collectors have become a key material for next-generation lithium batteries due to their advantages such as high safety, low cost and lightweight.

[0003] However, in practical applications, especially in the all-tab battery structure, the welding process faces severe challenges. First, the polymer insulation layer in the middle of the composite copper foil generates gas when heated during ultrasonic welding. The gas cannot be discharged in time, resulting in blistering and poor welding in the welding area, which greatly reduces the welding strength and yield. Second, the total copper thickness of the composite copper foil is relatively thin, resulting in a large sheet resistance. During high-rate charging and discharging, the welding area generates concentrated heat, affecting the battery's electrical performance and safety. Utility Model Content

[0004] The purpose of this invention is to solve the problem of difficult welding process in all-tab battery structure, and to provide a composite copper foil with locally enhanced welding area. Without significantly increasing the overall weight and cost, it locally and selectively reduces the sheet resistance of the welding area, thereby effectively reducing the overall internal resistance of the battery and the thermal effect of the welding point, and improving the rate performance and safety of the battery.

[0005] To achieve the above objectives, the technical solution of this utility model is as follows: A composite copper foil with a locally reinforced welding area includes a composite copper foil body, a predetermined welding area of ​​the composite copper foil body having a through hole, and a metal foil disposed on the predetermined welding area of ​​the composite copper foil body for welding with an electrode tab, the metal foil covering the through hole.

[0006] Preferably, the thickness of the metal foil is no greater than 1 μm.

[0007] Preferably, the metal foil is a pure copper foil.

[0008] Preferably, the metal foil is attached to a predetermined welding area of ​​the composite copper foil body by an adhesive layer.

[0009] Preferably, the entire surface of the metal foil on the side closest to the composite copper foil body is adhered to the adhesive layer.

[0010] Preferably, the adhesive layer is a dry film formed by curing conductive adhesive.

[0011] Preferably, the thickness of the adhesive layer is set to 0.5-1 μm.

[0012] Preferably, the diameter of the through hole is set to 10-150 μm.

[0013] Preferably, the composite copper foil body includes a substrate, and a copper layer is respectively provided on at least one side of the substrate and the inner wall of the through hole, and the metal foil is connected to the copper layer on one side of the substrate through an adhesive layer.

[0014] Compared with the prior art, the beneficial effects of this utility model are as follows: In the technical solution provided by this utility model, the through hole provides an effective escape channel for the gas generated during the welding process, fundamentally eliminating bubbling and incomplete welding. By using metal foil, the sheet resistance of the welding area is selectively and precisely reduced by about 40% without significantly changing the overall thickness and weight of the current collector. This effectively reduces the overall internal resistance of the battery and the heat generated at the welding point, enabling the battery to have better fast charging and discharging capabilities and reducing performance degradation during cycling. Attached Figure Description

[0015] The disclosure of this utility model is illustrated with reference to the accompanying drawings. It should be understood that the drawings are for illustrative purposes only and are not intended to limit the scope of protection of this utility model. In the drawings, the same reference numerals are used to refer to the same parts. Wherein: Figure 1 This is a schematic diagram of the structure of this utility model.

[0016] The diagram is labeled as follows: 1. Substrate; 2. First copper layer; 3. Second copper layer; 4. Metal foil; 5. Adhesive layer; 6. Through hole. Detailed Implementation

[0017] It is readily understood that, based on the technical solution of this utility model, those skilled in the art can propose various interchangeable structural methods and implementations without altering the essential spirit of this utility model. Therefore, the following detailed embodiments and accompanying drawings are merely illustrative descriptions of the technical solution of this utility model and should not be considered as the entirety of this utility model or as limitations or restrictions on the technical solution of this utility model.

[0018] like Figure 1As shown, a specific embodiment of a composite copper foil with a locally reinforced welding area provided by this utility model includes a substrate 1. The substrate 1 is made of a non-polar or low surface energy polymer material, such as PP, PE, PS, PTFE, PMMA, PET, PA, PI, etc. The thickness of the substrate 1 is set to 2.5-8μm. A plurality of through holes 6 are provided in the predetermined welding area of ​​the substrate 1. The pore diameter of the through holes 6 is set to 10-150μm, and the density of the through holes 6 is set to 20-200. The substrate 1 has copper plating on both sides as the first copper layer 2, and a second copper layer 3 is water-plated on the first copper layer 2. It should be noted that the first copper layer 2 and the second copper layer 3 can also be plated on only one side of the substrate 1. This embodiment uses copper plating on both sides of the substrate 1 for illustration. The inner wall of the through hole 6 is plated with the first copper layer 2 and the second copper layer 3 of the same thickness. The through hole 6 provides an effective escape channel for the gas generated during the welding process, which fundamentally eliminates bubbling and poor soldering. This allows the metal-to-metal interface to be in direct contact, with a strong bonding force. The welding tensile strength can be increased by more than 30%, and the welding yield is significantly improved, which greatly improves the process window and consistency of battery manufacturing.

[0019] A metal foil 4 is attached to the predetermined welding area of ​​the second copper layer 3 on one side of the substrate 1 via an adhesive layer 5. The metal foil 4 is used to weld with the tab. The adhesive layer 5 is a dry film formed by curing conductive adhesive, and the thickness of the adhesive layer 5 is set to 0.5-1μm to ensure conductivity. The metal foil 4 covers the through hole 6, and the thickness of the metal foil 4 is no more than 1μm to ensure that it does not significantly increase the overall weight and cost. The metal foil 4 is a pure copper foil. The entire surface of the metal foil 4 on the side close to the composite copper foil body is attached to the adhesive layer 5 to ensure stable attachment. By attaching the metal foil 4 to the predetermined welding area, the sheet resistance of the welding area is locally and selectively reduced significantly without significantly increasing the overall weight and cost. The sheet resistance of the welding area is reduced by about 40%, thereby effectively reducing the overall internal resistance of the battery and the thermal effect of the welding point. This gives the battery better fast charging and discharging capabilities, reduces performance degradation during cycling, and improves the rate performance and safety of the battery.

[0020] It should also be noted that the metal foil 4 is obtained by transferring copper after plating on the release film. It cleverly utilizes the poor adhesion between the release film and copper, turning it into an advantage that can achieve perfect transfer of ultra-thin copper foil, thereby filling the gap in the existing technology and preparing the required independent, ultra-thin, and dense metal foil 4.

[0021] There is a strong synergistic effect between the metal foil 4 and the through hole 6. The low-resistance additional metal foil 4 provides a better ultrasonic energy conduction path, which promotes welding. The through hole 6 ensures effective venting while ensuring a perfect combination of the welding interface under a better energy path. Together, they fundamentally overcome the last obstacle for composite current collectors to move towards the application of all tabs.

[0022] The technical scope of this utility model is not limited to the content described above. Those skilled in the art can make various modifications and variations to the above embodiments without departing from the technical concept of this utility model, and all such modifications and variations should fall within the protection scope of this utility model.

Claims

1. A composite copper foil with a locally reinforced welding zone, characterized in that: The composite copper foil body includes a predetermined welding area with a through hole (6), and a metal foil (4) is provided on the predetermined welding area of ​​the composite copper foil body for welding with a tab, the metal foil (4) covering the through hole (6).

2. The composite copper foil with a locally reinforced welding zone according to claim 1, characterized in that: The thickness of the metal foil (4) is no greater than 1 μm.

3. The composite copper foil with a locally reinforced welding zone according to claim 1, characterized in that: The metal foil (4) is set as pure copper foil.

4. The composite copper foil with a locally reinforced welding zone according to any one of claims 1-3, characterized in that: The metal foil (4) is attached to the predetermined welding area of ​​the composite copper foil body by an adhesive layer (5).

5. The composite copper foil with a locally reinforced welding zone according to claim 4, characterized in that: The entire surface of the metal foil (4) on the side closest to the composite copper foil body is adhered to the adhesive layer (5).

6. The composite copper foil with a locally reinforced welding zone according to claim 4, characterized in that: The adhesive layer (5) is a dry film formed by curing conductive adhesive.

7. The composite copper foil with a locally reinforced welding zone according to claim 4, characterized in that: The thickness of the adhesive layer (5) is set to 0.5-1 μm.

8. The composite copper foil with a locally reinforced welding zone according to claim 1, characterized in that: The diameter of the through hole (6) is set to 10-150 μm.

9. The composite copper foil with a locally reinforced welding zone according to claim 1, characterized in that: The composite copper foil body includes a substrate (1), and a copper layer is provided on at least one side of the substrate (1) and the inner wall of the through hole (6). The metal foil (4) is connected to the copper layer on one side of the substrate (1) through an adhesive layer (5).

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