Early monitoring and warning of overcharge thermal runaway in lithium-ion battery under various charging methods

Abstract

In order to advance the early warning time window for overcharge-induced thermal runaway in lithium-ion batteries and enhance the accuracy and real-time monitoring of battery safety status, a novel early warning model for overcharge-induced thermal runaway is proposed. Experiments were conducted on the thermal runaway behavior of ternary lithium-ion batteries under various overcharging rates, the effects of constant current constant voltage (CC-CV) overcharge and constant current (CC) overcharge on the thermal runaway behavior of lithium-ion batteries were compared. The results indicate that the internal temperature during CC overcharging is higher than that during CC-CV overcharging. Under the CC-CV charging mode, the temperature differences between the internal and external maximum temperatures at 0.5 C and 7 C overcharges are 55 °C and 29.5 °C, respectively. Under the CC charging mode, the maximum temperature differences between the inside and outside of the battery at 0.5 C and 7 C overcharges reach 75.2 °C and 66.1 °C, respectively. Notably, high-rate CC overcharging (5 C, 7 C) can trigger the opening of the battery’s pressure relief valve, with the maximum internal temperature reaching 115 °C. The characteristic parameters of thermal runaway caused by CC charging were extracted, and a two-level early warning model for overcharge-induced thermal runaway in lithium-ion batteries was established, leveraging the multi-parameter coupling of external temperature, temperature rise rate, and voltage.