Fast and Energy-Efficient Compound Self-Heating of Automotive Batteries Based on Electrochemical-Thermal-Stress Aging Model

To alleviate severe power and energy degradation of Lithium-ion batteries (LIBs) at cold climates, compound heating has gained widespread attention due to its remarkable heating rate and simple structure. Heating speed and battery health are two critical performance indices to evaluate a heating strategy, while they are usually contrary. To balance heating speed and capacity degradation, we develop an electrochemical-thermal-stress coupled aging model, which can accurately predict voltage, temperature, and capacity evolution during self-heating. Based on the coupled model, the optimal discharge heating curve is determined by the model predictive control (MPC) method for the first time. Moreover, an integrated compound battery self-heater (ICBSH) based on reconfiguration of traction motor drives is proposed to achieve dynamic current regulation and eliminate additional on-board costs. Downscaled experiments demonstrate that the MPC optimization heating method can effectively preheat LIBs from -20 °C to 0 °C within 95.6 s, with a capacity loss of only 3.2% after 280 heating times. In comparison with constant current discharging method, the MPC optimization heating method reduces heating time by 27% and energy consumption by 8%, without accelerating capacity degradation.