Influence of Connector Material on Temperature Rise under High-Current Discharge
High-current discharge is one of the common operating conditions in practical applications of power battery and energy storage systems. As the discharge rate increases, the heat generation at each connection node inside the battery pack rises exponentially. As the core structural component for current conduction between individual cells, the material selection of connector strips directly determines the internal resistance and temperature rise performance of the entire battery pack, which further affects the safety, stability and service life of the system.
Test Background and Conditions
To objectively evaluate the practical performance of connector strips with different materials, a comparative temperature rise test was conducted on 18650 battery packs adopting Cu-Sn alloy strips and pure Ni strips respectively. All tests were carried out under identical environmental conditions and consistent discharge current parameters. Two typical high-current working conditions, 55A and 60A discharge, were covered in the test. Three critical indicators were monitored throughout the experiment, including negative electrode strip temperature, MOS temperature and cell temperature.
Test Results
The test data indicates that the Cu-Sn alloy strip presents significantly lower temperature at all measuring points compared with the pure Ni strip.
Under 55A discharge condition, the negative electrode temperature of the Cu-Sn alloy strip is 78.5°C, while that of the pure Ni strip is 126°C, with a temperature difference of 47.5°C. The MOS temperature of the Cu-Sn alloy strip is 67.7°C, versus 104.3°C for the pure Ni strip, creating a temperature difference of 36.6°C.
Under 60A discharge condition, the performance gap is further enlarged. The negative electrode temperature of the Cu-Sn alloy strip is 85.6°C, while the pure Ni strip reaches 148°C, with a temperature difference of 62.4°C. The MOS temperature of the Cu-Sn alloy strip is 84.4°C, compared with 106.7°C of the pure Ni strip, with a temperature difference of 22.3°C. Meanwhile, the battery cell temperature maintains a lower level with the application of Cu-Sn alloy strips.
Impacts of Excessive Temperature Rise
Operation of batteries under high temperature conditions accelerates electrolyte decomposition and electrode material aging, which greatly reduces the cycle life of batteries. In addition, continuous high temperature raises the risk of battery thermal runaway. Especially under high-rate discharge working conditions, local overheating at the connecting strips is a critical inducement for battery system safety hazards.
Test Conclusion
With lower contact internal resistance and excellent electrical conductivity, the Cu-Sn alloy connecting strip produces less heat and achieves milder temperature rise during high-current discharge. Its thermal advantage becomes more prominent with the increase of discharge current, and the heat generation gap between Cu-Sn alloy strips and pure Ni strips is further widened under higher current conditions.
This superior performance makes Cu-Sn alloy strips highly applicable for high-rate power equipment, electric tools, energy storage power supplies and other scenarios requiring continuous high-current output. It can effectively reduce the thermal risk of battery packs under heavy-load operation, and significantly improve the operational stability and overall cycle life of the battery system.
Test Results
The test data shows that the temperature of the Cu-Sn alloy strip at all measuring points is significantly lower than that of the pure Ni strip: Under 55A discharge condition, the negative electrode temperature is 78.5°C, while that of the pure Ni strip is 126°C, with a temperature difference of 47.5°C; the MOS temperature is 67.7°C, while that of the pure Ni strip is 104.3°C, with a temperature difference of 36.6°C.
Under 60A discharge condition, the gap is further widened. The negative electrode temperature reaches 85.6°C, while that of the pure Ni strip is 148°C, with a temperature difference of 62.4°C; the MOS temperature is 84.4°C, while that of the pure Ni strip is 106.7°C, with a temperature difference of 22.3°C. The cell temperature is also maintained at a lower level.
Impacts of Excessive Temperature Rise
When batteries operate at high temperatures, electrolyte decomposition and electrode material aging will be accelerated, resulting in a sharp decline in cycle life. Meanwhile, sustained high temperature increases the risk of thermal runaway. Especially under high-rate discharge scenarios, local overheating at the connecting strips is a major trigger for safety hazards.
Test Conclusion
Benefiting from lower contact internal resistance and superior electrical conductivity, the Cu-Sn alloy connecting strip generates less heat and exhibits milder temperature rise during high-current discharge. Moreover, its advantage in temperature rise expands as the discharge current increases — the higher the current, the more obvious the heat generation gap.
This feature makes it particularly suitable for high-rate power equipment, power tools, energy storage power supplies and other applications requiring continuous high-current output. It can effectively reduce thermal risks of battery packs under heavy-load conditions, and improve system operation stability and overall cycle life.
