A variable-frequency self-heating strategy for lithium-ion batteries based on an electrochemical impedance-thermal coupling model applicable to a wide frequency range

A novel electrochemical impedance-thermal coupling model suitable for alternating current (AC) heating over a wide frequency range is proposed, that considers the influence of the high-frequency skin effect on the heat generation rate of the battery according to electrochemical impedance spectroscopy (EIS) test results. After obtaining the model parameters by NSGA-II algorithm and the high-frequency heat from the charge transport, the accuracy of the proposed model is verified using a topology that relies on the batteries to generate high-frequency AC for full-cycle heating. With the terminal voltage as the limit and the shortest heating time as the target, a strategy is developed for fast low-temperature variable-frequency AC self-heating. Experiments demonstrate that the battery can be heated from −15 °C to 0 °C in 347 s under this strategy. Finally, the proposed heating strategy is proved to have no effect on the battery state of health (SOH) by the incremental capacity (IC) curve, battery capacity and internal resistance changes before and after 50 heating cycles.