Capacity degradation minimization oriented optimization for the pulse preheating of lithium-ion batteries under low temperature

Preheating lithium-ion batteries can effectively solve the problem of their poor performance at low temperatures. Pulse heating is recognized as a feasible solution to pre-heating. However, if pulse current is used to heat a battery, it may lead to significant capacity fading when inappropriate frequency and amplitude values are adopted. Therefore, the pulse pre-heating strategy should be optimized to decrease capacity degradation. This research focuses on the influencing effectiveness of the frequency and amplitude of the required pulse heating current for pre-heating lithium-ion batteries. An electro-thermal model of a lithium-ion battery was established based on its electrochemical impedance spectroscopy (EIS) at different temperatures. Based on the proposed model, the maximum permissible amplitudes of the pulse current at different frequencies and different temperatures were obtained to reduce the lithium plating. Also, the optimal strategy was verified using a comparison experiment, where the EIS and the differential voltage were used as indicators. Overall, the results showed that the proposed strategy can heat Li-ion batteries from-20 degrees C to 5 degrees C within 308 s, with only a 0.035% decrease in the capacity after 30 cycles.