Connection method of carbon-based current collector and metal tab

Abstract

The invention relates to the technical field of heterogeneous component connection, in particular to a connection method of a carbon-based current collector and a metal tab. According to the technical scheme, the method comprises the following steps: providing a carbon-based current collector, and reserving an electroplating area; electroplating a metal coating on the electroplating area; and welding a metal tab on the electroplating area. According to the invention, firm mechanical connection and stable electric connection between the carbon-based current collector and the metal tab are realized through a process of combining electroplating and welding, the interface bonding strength is effectively improved, and the electron conduction efficiency is remarkably improved; the method has wide material compatibility, can adapt to tabs made of different materials and various carbon-based current collectors, avoids using substances harmful to the environment, meets the requirement of green manufacturing, and is simple and feasible in process.

Description

Technical Field

[0001] This invention relates to the field of heterogeneous component connection technology, and in particular to a method for connecting a carbon-based current collector to a metal tab. Background Technology

[0002] Aqueous batteries have shown great promise for large-scale energy storage due to their advantages such as high safety, low cost, and environmental friendliness. However, compared with battery systems using organic electrolytes, aqueous batteries have a narrower operating voltage window and face challenges in electrochemical stability, which places more stringent requirements on the interfacial compatibility between electrodes and current collectors.

[0003] Currently, lithium-ion batteries use aluminum and copper metal current collectors. However, these metal materials are prone to side reactions such as electrochemical corrosion, hydrogen evolution, or oxidation when operating in aqueous electrolytes for extended periods. These problems lead to current collector performance degradation, increased interfacial contact resistance, and consequently, shortened battery cycle life and decreased overall electrochemical performance. While lead current collectors in lead-acid batteries offer strong corrosion resistance, they pose a risk of environmental pollution.

[0004] To address the aforementioned issues, carbon-based materials (such as carbon cloth, carbon paper, and carbon felt) are considered ideal alternative current collectors. They possess excellent chemical inertness, resisting corrosion from acidic and alkaline electrolytes and effectively suppressing side reactions. Simultaneously, carbon materials exhibit good electrical conductivity, low density, and a tunable porous structure. This porous structure not only facilitates electrolyte wetting and ion transport but also improves the reaction kinetics at the electrode / current collector interface.

[0005] However, the inherent porosity and rough surface of carbon-based current collectors make it difficult to achieve the high hermeticity of encapsulation like dense metal foils, posing a risk of electrolyte leakage or moisture evaporation. Therefore, external metal tabs are usually required to complete the final battery encapsulation. However, significant differences exist between carbon-based current collectors and metal tabs in their physical properties (such as coefficient of thermal expansion, hardness, and melting point) and chemical properties, resulting in interface incompatibility and making it difficult to achieve a strong, low-resistance connection using traditional welding methods (such as fusion welding).

[0006] In existing technologies, carbon-based current collectors and metal tabs are typically bonded together using only external mechanical pressure. While this connection method can conduct current, its mechanical strength is low, making it prone to loosening during long-term battery operation or when subjected to vibration, leading to increased contact resistance and even failure. More importantly, the high ohmic resistance at the interface reduces the battery's charge / discharge efficiency and power density.

[0007] To improve connection performance, existing technologies have proposed several solutions. For example, patent document CN106602077B discloses a method using low-melting-point lead tabs, which involves pressing molten lead into the pores of conductive carbon felt under air pressure to form an interlocking structure. Another patent document, CN106695193B, uses resistance spot welding to locally melt the sheet-like lead tabs, allowing the molten lead to penetrate into the gaps in the carbon felt before cooling and solidifying to achieve the connection. These methods improve connection strength and conductivity to some extent.

[0008] However, the aforementioned existing technologies all rely on low-melting-point lead as the connecting medium. This leads to two significant drawbacks: first, lead is a toxic heavy metal, and its use and disposal may cause environmental pollution problems, which contradicts the development concept of green energy storage; second, lead tabs are not suitable for all types of aqueous batteries, for example, they may be incompatible with systems such as aqueous zinc-ion batteries. Therefore, this application proposes a method for connecting a carbon-based current collector to a metal tab. Summary of the Invention

[0009] The purpose of this invention is to address the environmental pollution caused by existing technologies relying on low-melting-point lead as a connecting medium, and to propose a method for connecting a carbon-based current collector to a metal tab.

[0010] The technical solution of the present invention: a method for connecting a carbon-based current collector to a metal tab, comprising the following steps:

[0011] S1. Provide carbon-based current collectors and reserve an electroplating area;

[0012] S2. Electroplating a metal coating in the electroplating area;

[0013] S3. Weld the metal tabs onto the electroplating area.

[0014] Optionally, the carbon-based current collector is selected from carbon cloth, carbon felt, or carbon paper.

[0015] Optionally, the electroplated metal coating material can be any metal, such as one or more of copper, nickel, and tin.

[0016] Optionally, the welding is spot welding, laser welding, or tin soldering.

[0017] Optionally, in the electroplating step, the deposition amount of the metal coating is from 50 mAh to 1000 mAh.

[0018] Optionally, the metal tabs can be made of any metal, such as stainless steel, nickel, titanium, copper, or tin.

[0019] Optionally, the electroplating step uses an electroplating solution, which includes a copper sulfate solution, nickel chloride, or a nickel chloride solution.

[0020] Optionally, the electroplated area is cleaned and dried after metal deposition by electroplating before welding.

[0021] Compared with the prior art, this application includes at least one of the following beneficial technical effects:

[0022] The method of the present invention achieves a strong connection between the carbon-based current collector and the metal tab, significantly improving the mechanical strength and reliability of the connection.

[0023] By forming a metal coating on the carbon-based surface, the interfacial contact characteristics are effectively improved, the contact resistance is reduced, and the electronic conduction efficiency is enhanced.

[0024] This invention has broad applicability, enabling connections between metal tabs of different materials and various types of carbon-based current collectors. It avoids the use of environmentally harmful metal materials, thus better meeting the requirements of green manufacturing. The connection process is simple and feasible, and has good compatibility with existing battery manufacturing processes.

[0025] In summary, this invention achieves a strong mechanical connection and stable electrical connection between the carbon-based current collector and the metal tab through a combination of electroplating and welding processes, effectively improving the interfacial bonding strength and significantly enhancing electron conduction efficiency. This method has broad material compatibility, can adapt to tabs of different materials and various carbon-based current collectors, avoids the use of environmentally harmful substances, meets green manufacturing requirements, and its process is simple and feasible. Attached Figure Description

[0026] Figure 1 A flowchart illustrating a method for connecting a carbon-based current collector to a metal tab.

[0027] Figure 2 a is a schematic diagram of copper deposition on carbon cloth in Example 1. Figure 2 b is a diagram of the welding of deposited copper carbon cloth and stainless steel electrode tabs in Example 1;

[0028] Figure 3 a is a schematic diagram of nickel deposition on carbon felt in Example 3. Figure 3 b is a diagram of the welding of the deposited nickel-carbon felt and the metallic nickel tab in Example 3. Detailed Implementation

[0029] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features described therein can be combined with each other.

[0030] Example 1: As Figure 1 This embodiment provides a method for connecting a carbon-based current collector to a metal tab, specifically a method for connecting a carbon cloth current collector to a stainless steel tab.

[0031] Prepare the carbon-based current collector: Cut the commercial carbon cloth into rectangular sheets with dimensions of 1 cm × 2.5 cm, and clearly reserve a 1 cm × 1 cm area as the electroplating connection area.

[0032] Prepare the electroplating solution: Prepare 100 mL of acidic copper sulfate electroplating solution, in which the concentration of copper sulfate pentahydrate (CuSO4·5H2O) is 200 g / L and the concentration of sulfuric acid (H2SO4) is 50 g / L.

[0033] Electroplating of the metal layer: Using pretreated carbon cloth as the cathode and a pure copper plate as the anode, electroplating deposition is performed at room temperature. A constant current mode is used, controlling the deposition charge to be 100 mAh. At this time, metallic copper is uniformly deposited into the electroplating area of ​​the carbon cloth, filling its fiber pores and forming a dense and firmly bonded copper plating layer.

[0034] Post-treatment: After electroplating, remove the carbon cloth deposited with copper, rinse thoroughly with deionized water to remove residual electroplating solution, and then dry in a vacuum oven at 60°C for 2 hours.

[0035] Welding tabs: such as Figure 2 As shown in Figure a, a metal tab of suitable size made of 304 stainless steel is accurately placed over the copper-plated area of ​​the carbon cloth. Using a commercial spot welding machine, with appropriate welding parameters (such as current, pressure, and time) adjusted, the tab and the copper plating are spot welded together. Figure 2 As shown in b.

[0036] Performance testing: The interface resistance of the connected electrodes was measured using the four-probe method. Test results show that, compared to equivalent electrodes connected solely by external mechanical pressure, the sample prepared using the method of this invention exhibits a more than 30% reduction in interface resistance, significantly improving electron conduction efficiency.

[0037] Example 2: Connection and strength test between carbon cloth current collector and nickel electrode tab

[0038] Prepare the carbon-based current collector: Cut the carbon cloth into a rectangle of 1 cm × 2.5 cm, leaving a 1 cm × 1 cm electroplating area.

[0039] Preparation of electroplating solution: Prepare 100 mL of Watts-type nickel electroplating solution, the main components of which are: nickel chloride hexahydrate (NiCl2·6H2O) 150 g / L, boric acid (H3BO3) 40 g / L.

[0040] Electroplating metal layer: Using carbon cloth as the cathode and nickel plate as the anode, electroplating is carried out under the condition of deposition charge of 100 mAh to form a nickel plating layer on the surface of carbon cloth.

[0041] Post-processing: After electroplating, the sample is removed, washed with deionized water, and dried at 60°C.

[0042] Welding tabs: A nickel metal tab is attached to the nickel plating of the carbon cloth and firmly connected by spot welding.

[0043] Mechanical strength test: The peel strength of the connection point was tested using a universal tensile testing machine. The test results showed that the connection point could withstand a vertical tensile force of at least 10 N without falling off or breaking, demonstrating the excellent mechanical connection strength achievable by the method of this invention.

[0044] Example 3: Connection between carbon felt current collector and nickel electrode tab

[0045] Prepare the carbon-based current collector: Take a piece of carbon felt material with a thickness of 5 mm, cut it into a rectangular block of 1 cm × 2.5 cm, and leave a 1 cm × 1 cm electroplating area. Due to the large thickness and more pores of the carbon felt, more metal needs to be deposited to ensure the formation of an effective connection channel.

[0046] Preparation of electroplating solution: Use 100 mL of the same nickel chloride electroplating solution as in Example 2.

[0047] Electroplated metal layer: The carbon felt is placed in the electroplating solution and the deposition charge is increased to 750 mAh, so that the nickel metal can fully penetrate and fill the three-dimensional network structure inside the carbon felt, forming a strong metal composite inside and on the surface.

[0048] Post-processing: Remove the sample, wash and dry it.

[0049] Soldering tabs: Use soldering process, such as... Figure 3 As shown in Figure a, a nickel metal tab is soldered to a carbon felt area where nickel has already been deposited. The solder wets and bonds well with the pre-deposited nickel plating, thus achieving a reliable connection, as shown in Figure a. Figure 3 As shown in b.

[0050] Performance testing: Resistance testing shows that the electrode resistance after connecting the carbon felt and nickel tab in this embodiment is reduced by more than 33% compared with the traditional crimping method, effectively solving the problem of high resistance connection between thick carbon substrate and metal tab.

[0051] The following table summarizes the performance data comparison between traditional extrusion connections and the connection methods in Examples 1-3:

[0052] Table 1: Comparison of Connection Performance between Different Metal Tabs and Carbon-based Current Collectors

[0053] Connection method sample Resistance (Ω) Tensile test (N) Traditional extrusion connection (pressure ~20 kPa) Carbon cloth-stainless steel tabs 2.2 <2.5 Example 1 Carbon cloth-stainless steel tabs 1.5 >10 Traditional extrusion connection (pressure ~20 kPa) Carbon cloth-nickel metal tabs 1.6 <2.5 Example 2 Carbon cloth-nickel metal tabs 1.0 >10 Traditional extrusion connection (pressure ~20 kPa) Carbon felt-nickel metal tabs 3.4 <2.5 Example 3 Carbon felt-nickel metal tabs 2.2 >10

[0054] According to the performance comparison data shown in Table 1, the electroplating and welding combination connection method proposed in this invention is significantly superior to the traditional extrusion connection method in both electrical performance and mechanical strength. Under the same material combination, the connection resistance of the samples using the method of this invention is significantly lower than that of the samples connected by traditional extrusion, indicating that this method effectively reduces interfacial contact resistance and improves electron conduction efficiency. Meanwhile, tensile test results consistently show that the mechanical load-bearing capacity of the samples connected by the method of this invention is much higher than that of the traditional extrusion connection method, proving that this method can achieve a more robust and reliable mechanical connection. These performance advantages have been verified in combinations of different types of carbon-based current collectors and metal tabs of different materials, demonstrating the effectiveness and universality of the connection method of this invention.

[0055] In summary, this invention successfully overcomes the obstacle of direct welding between carbon materials and metals due to their significant differences in physicochemical properties by employing a two-stage connection strategy: first, electroplating a metal layer onto the carbon-based current collector as a transition interface, and then welding it to the metal tabs. This method is simple, widely applicable, and not only significantly reduces interfacial contact resistance and improves electron conduction efficiency, but also imparts excellent mechanical strength to the connection points, thereby comprehensively enhancing the overall performance of aqueous batteries using carbon-based current collectors.

[0056] It is worth noting that the connection method provided by this invention can achieve a firm mechanical connection and a stable electrical connection between the carbon-based current collector and the metal tab, significantly improving the reliability of the connection. This method forms a metal coating on the surface of the carbon-based current collector through electroplating, effectively reducing the interfacial contact resistance and improving the electron conduction efficiency, resulting in a more than 30% reduction in electrode resistance compared to traditional press-fit methods. This method has wide applicability and can reliably connect metal tabs made of various materials such as stainless steel, nickel, and copper to different carbon-based current collectors such as carbon cloth and carbon felt. This process avoids the use of environmentally harmful metals such as lead, solving the lead pollution problem in existing technologies, and is also suitable for battery systems with high material compatibility requirements, such as aqueous zinc-ion batteries. This connection method is simple and has good compatibility with existing battery manufacturing processes.

[0057] The above specific embodiments are merely several optional embodiments of the present invention. Based on the technical solutions of the present invention and the relevant teachings of the above embodiments, those skilled in the art can make various alternative improvements and combinations to the above specific embodiments.

Claims

1. A method of connecting a carbon-based current collector to a metal tab, the method comprising: The method comprises the following steps: S1. providing a carbon-based current collector and reserving an electroplating area; S2. electroplating a metal plating layer on the electroplating area; S3. welding a metal tab on the electroplating area.

2. The method of connecting a carbon-based current collector to a metal tab according to claim 1, wherein, The carbon-based current collector is selected from carbon cloth, carbon felt or carbon paper.

3. The method of claim 1, wherein the carbon-based current collector is a carbon-based current collector having a surface roughness of 0.5 μm or less. The electroplated metal plating layer is made of any one or more of copper, nickel and tin.

4. The method of claim 1, wherein the carbon-based current collector is a carbon-based current collector having a surface roughness of 0.5 μm or less. The welding is spot welding, laser welding or soldering.

5. The method of claim 1, wherein the carbon-based current collector is a carbon-based current collector having a surface roughness of 0.5 μm or less. In the electroplating step, the deposition amount of the metal plating layer is 50 mAh to 1000 mAh.

6. The method of claim 1, wherein the carbon-based current collector is a carbon-based current collector having a surface roughness of 0.5 μm or less. The metal tab is made of any one of stainless steel, nickel, titanium, copper and tin.

7. The method of claim 1, wherein the carbon-based current collector is a carbon-based current collector having a surface roughness of 0.5 μm or less. The electroplating step uses an electroplating solution comprising a copper sulfate solution, a nickel chloride solution or a tin chloride solution.

8. The method of claim 1, wherein the carbon-based current collector is a carbon-based current collector having a surface roughness of 0.5 μm or less. After the electroplating deposition of the metal on the electroplating area, cleaning and drying treatment are performed, and then welding is performed.

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