What role does the nickel strip play in a battery?
Nickel strips are widely used in lithium battery manufacturing, which is highly consistent with its unique physical and chemical properties and the functional requirements of lithium batteries. The following is an analysis from two aspects: core reasons and specific functions:
I. The core reasons for nickel strips in lithium battery manufacturing
1. Excellent conductivity and stability
Conductive performance: The conductivity of pure nickel is about 5.9×10⁷ S/m (second only to copper and silver), which can ensure efficient transmission of current inside the battery and reduce energy loss.
Environmental stability: During the charging and discharging process of lithium batteries (especially in high voltage and high current scenarios), the resistance fluctuation of nickel strips is small, and it is not easy to cause poor contact due to temperature changes (-40℃~85℃).
2. Good corrosion resistance and chemical compatibility
Anti-electrolyte corrosion: The electrolyte of lithium batteries is mostly a carbonate solution of lithium hexafluorophosphate (LiPF₆), which is weakly acidic. A nickel oxide (NiO) passivation film is easily formed on the surface of nickel strips to prevent further corrosion, while metals such as iron and aluminum are easily corroded by electrolytes.
No risk of chemical reaction: Nickel and lithium (Li) have no violent side reactions, avoiding material failure or safety hazards (compared to copper strips, which may form alloys with lithium, causing structural damage).
3. Excellent processing performance and welding adaptability
Ductility: Nickel strips can be processed to ultra-thin thicknesses of 0.05~2mm and are not easy to break, suitable for the compact space layout of precision batteries (such as soft-pack batteries and cylindrical batteries).
Welding reliability: Nickel strips and tabs (usually aluminum or copper) and shells (stainless steel/aluminum) can be firmly connected through ultrasonic welding and laser welding, and the tensile strength of the weld can reach 50~100MPa, which is much higher than traditional riveting or gluing processes.
4. Balance between cost and safety
Cost-effectiveness: Although the cost is higher than nickel-plated steel strips, it is lower than pure copper strips, and the comprehensive performance (conductivity, corrosion resistance, welding) is better, suitable for large-scale industrial production.
Safety redundancy: Nickel strips have a certain degree of flexibility, which can buffer the volume expansion of the battery during charging and discharging (about 10%~20%), reducing the risk of tab breakage or short circuit.
II. The specific role of nickel strips in lithium batteries
1. Tab connection and current conduction
Action scenario: Connect the positive and negative tabs with the external circuit (such as the busbar of the battery module) to form a current path.
Key value:
Ensure the low-impedance connection between the tabs (positive aluminum foil, negative copper foil) and the external conductor to reduce the internal resistance of the battery (usually increase the internal resistance by < 5mΩ).
Disperse the current density at the tabs to avoid local overheating (such as when discharging with a large current, the nickel strip can control the temperature at ≤60℃).
2. Structural support and fixation of battery modules
Action scenario: As a connecting piece between the cells in the module, fix the cell position and transmit mechanical stress.
Key value:
Use the elastic deformation of the nickel strip to absorb vibration energy (such as bumps during driving of the car) and reduce the risk of diaphragm puncture caused by cell displacement.
Ultra-thin nickel strips (such as 0.1mm) can fit closely to the surface of the cell, saving module space and increasing energy density (about 5~10Wh/L).
3. Safety protection and thermal management assistance
Fuse protection: Some nickel strips are designed as fusible structures (such as hollow or thinned areas). When the battery is overcurrent (such as short-circuit current > 100A), the nickel strip will fuse before the battery cell, cut off the circuit, and prevent thermal runaway.
Heat conduction and heat dissipation: The thermal conductivity of the nickel strip is 90W/(m·K), which can transfer the heat of the battery cell to the module shell or water cooling plate. When used with thermal conductive glue, the thermal resistance can be reduced by 30%~50%.
4. Process compatibility and standardized production
Automation adaptation: Nickel strips can be formed by high-speed punching and rolling, and can adapt to the winding, lamination and other automated processes of lithium battery production lines, with a production efficiency of 50~100 pieces/minute.
Unified industry standards: Mainstream lithium battery manufacturers (such as CATL and Panasonic) use nickel strips as standard connection materials to facilitate supply chain collaboration and quality control.
III. Future trends: performance upgrade and material innovation
Ultra-thin and composite: Develop nickel strips with a thickness of less than 0.03mm, or nickel-copper-graphene composite strips, to further improve conductivity and flexibility.
No-plating: Replace traditional nickel plating with nano-coating technology (such as diamond-like coating) to reduce costs and improve corrosion resistance.
Recycling: Research on efficient disassembly technology of nickel strips (such as low-temperature brittle fracture separation), with the goal of increasing the nickel recovery rate from the current 70% to more than 95%, in line with the needs of the circular economy.
Nickel strips are still the "gold standard" of lithium battery connection materials with their comprehensive performance advantages, and their role is irreplaceable. As battery technology develops towards high energy density and long life, the performance optimization and innovative application of nickel strips will continue to be the focus of the industry.
What role does the nickel strip play in a battery?
Nickel strips are widely used in lithium battery manufacturing, which is highly consistent with its unique physical and chemical properties and the functional requirements of lithium batteries. The following is an analysis from two aspects: core reasons and specific functions:
I. The core reasons for nickel strips in lithium battery manufacturing
1. Excellent conductivity and stability
Conductive performance: The conductivity of pure nickel is about 5.9×10⁷ S/m (second only to copper and silver), which can ensure efficient transmission of current inside the battery and reduce energy loss.
Environmental stability: During the charging and discharging process of lithium batteries (especially in high voltage and high current scenarios), the resistance fluctuation of nickel strips is small, and it is not easy to cause poor contact due to temperature changes (-40℃~85℃).
2. Good corrosion resistance and chemical compatibility
Anti-electrolyte corrosion: The electrolyte of lithium batteries is mostly a carbonate solution of lithium hexafluorophosphate (LiPF₆), which is weakly acidic. A nickel oxide (NiO) passivation film is easily formed on the surface of nickel strips to prevent further corrosion, while metals such as iron and aluminum are easily corroded by electrolytes.
No risk of chemical reaction: Nickel and lithium (Li) have no violent side reactions, avoiding material failure or safety hazards (compared to copper strips, which may form alloys with lithium, causing structural damage).
3. Excellent processing performance and welding adaptability
Ductility: Nickel strips can be processed to ultra-thin thicknesses of 0.05~2mm and are not easy to break, suitable for the compact space layout of precision batteries (such as soft-pack batteries and cylindrical batteries).
Welding reliability: Nickel strips and tabs (usually aluminum or copper) and shells (stainless steel/aluminum) can be firmly connected through ultrasonic welding and laser welding, and the tensile strength of the weld can reach 50~100MPa, which is much higher than traditional riveting or gluing processes.
4. Balance between cost and safety
Cost-effectiveness: Although the cost is higher than nickel-plated steel strips, it is lower than pure copper strips, and the comprehensive performance (conductivity, corrosion resistance, welding) is better, suitable for large-scale industrial production.
Safety redundancy: Nickel strips have a certain degree of flexibility, which can buffer the volume expansion of the battery during charging and discharging (about 10%~20%), reducing the risk of tab breakage or short circuit.
II. The specific role of nickel strips in lithium batteries
1. Tab connection and current conduction
Action scenario: Connect the positive and negative tabs with the external circuit (such as the busbar of the battery module) to form a current path.
Key value:
Ensure the low-impedance connection between the tabs (positive aluminum foil, negative copper foil) and the external conductor to reduce the internal resistance of the battery (usually increase the internal resistance by < 5mΩ).
Disperse the current density at the tabs to avoid local overheating (such as when discharging with a large current, the nickel strip can control the temperature at ≤60℃).
2. Structural support and fixation of battery modules
Action scenario: As a connecting piece between the cells in the module, fix the cell position and transmit mechanical stress.
Key value:
Use the elastic deformation of the nickel strip to absorb vibration energy (such as bumps during driving of the car) and reduce the risk of diaphragm puncture caused by cell displacement.
Ultra-thin nickel strips (such as 0.1mm) can fit closely to the surface of the cell, saving module space and increasing energy density (about 5~10Wh/L).
3. Safety protection and thermal management assistance
Fuse protection: Some nickel strips are designed as fusible structures (such as hollow or thinned areas). When the battery is overcurrent (such as short-circuit current > 100A), the nickel strip will fuse before the battery cell, cut off the circuit, and prevent thermal runaway.
Heat conduction and heat dissipation: The thermal conductivity of the nickel strip is 90W/(m·K), which can transfer the heat of the battery cell to the module shell or water cooling plate. When used with thermal conductive glue, the thermal resistance can be reduced by 30%~50%.
4. Process compatibility and standardized production
Automation adaptation: Nickel strips can be formed by high-speed punching and rolling, and can adapt to the winding, lamination and other automated processes of lithium battery production lines, with a production efficiency of 50~100 pieces/minute.
Unified industry standards: Mainstream lithium battery manufacturers (such as CATL and Panasonic) use nickel strips as standard connection materials to facilitate supply chain collaboration and quality control.
III. Future trends: performance upgrade and material innovation
Ultra-thin and composite: Develop nickel strips with a thickness of less than 0.03mm, or nickel-copper-graphene composite strips, to further improve conductivity and flexibility.
No-plating: Replace traditional nickel plating with nano-coating technology (such as diamond-like coating) to reduce costs and improve corrosion resistance.
Recycling: Research on efficient disassembly technology of nickel strips (such as low-temperature brittle fracture separation), with the goal of increasing the nickel recovery rate from the current 70% to more than 95%, in line with the needs of the circular economy.
Nickel strips are still the "gold standard" of lithium battery connection materials with their comprehensive performance advantages, and their role is irreplaceable. As battery technology develops towards high energy density and long life, the performance optimization and innovative application of nickel strips will continue to be the focus of the industry.
