Experimental study on alternating current heating strategy for lithium-ion batteries based on lithium precipitation-overvoltage dual safety constraints

Battery preheating is critical for ensuring the safety and efficiency of lithium-ion batteries at low temperatures. In this study, an electro-thermal coupling model based on a second-order RQ equivalent circuit is developed to accurately predict battery thermal behavior under alternating current (AC) heating. Its performance is examined through comparative tests with different equivalent circuit models, and further validated via module-level experiments using the second-order RQ structure. A dual-safety constrained AC heating strategy considering both lithium plating and overvoltage limits is proposed to maximize heating rates while ensuring operational safety. Model predictions are validated by experiments at both cell and module levels. At an ambient temperature of −20 °C, the heating strategy achieves average temperature rise rates of 0.74 °C/min, 3.79 °C/min, and 5.24 °C/min for single cells at 70 %, 50 %, and 30 % state-of-charge (SOC), respectively; with the root mean squared error (RMSE) maintained within 19.3–28.7 mV for the voltage dynamic response and 0.18–0.26 °C for the temperature field across different SOC settings, corresponding rates for battery modules are 0.374 °C/min, 1.184 °C/min, and 3.36 °C/min. Extended cycling tests (500 cycles at 50 % SOC) demonstrate the safety and durability of the strategy, with capacity fading by only 77.4mAh (2.31 % SOH reduction), minimal internal resistance increase (2.15 mΩ for charging, 2.73 mΩ for discharging), high degree of the characteristic parameters' consistency of the incremental capacity curves and complete lamellar crystal structure in graphite microstructure. These results confirm that the proposed electro-thermal model and dual-safety AC heating strategy enable rapid and safe heating of lithium-ion batteries at low temperatures, providing both a theoretical and experimental foundation for advanced battery thermal management.