The polarization characteristics of lithium-ion batteries under cyclic charge and discharge

A high-fidelity electrochemical-thermal coupling was established to study the polarization characteristics of power lithium-ion battery under cycle charge and discharge. The lithium manganese oxide lithium-ion battery was selected to study under cyclic conditions including polarization voltage characteristics, and the polarization internal resistance characteristics of the power lithium-ion battery under cyclic conditions were analyzed via the Hybrid Pulse Power Test (HPPC). The results show that for different working conditions, the polarization voltage difference of the power lithium-ion battery is mainly affected by the change in polarization internal resistance. A higher charge-discharge rate, lower ambient temperatures, and more cycles lead to a greater polarization internal resistance of the battery. Meanwhile, the ohmic polarization internal resistance and the concentration polarization internal resistance of the power lithium-ion battery both exhibit different characteristics under different working condition. In addition, the internal resistance of the ohmic polarization is not affected by the change in current, but it is significantly affected by the change in ambient temperature. Therefore, the ohmic polarization voltage reacts rapidly with changes in the charge/discharge state of the battery; the change of the internal resistance of the concentration polarization is relatively slow.