Early warning method for thermal runaway of lithium-ion batteries under thermal abuse condition based on online electrochemical impedance monitoring

Early warning of thermal runaway (TR) of lithium-ion batteries (LIBs) is a significant challenge in current application scenarios. Timely and effective TR early warning technology is urgently required considering the current fire safety situation of LIBs. In this work, we report an early warning method of TR with online electrochemical impedance spectroscopy (EIS) monitoring, which overcomes the shortcomings of warning methods based on traditional signals such as temperature, gas, and pressure with obvious delay and high cost. With in-situ data acquisition through accelerating rate calorimeter (ARC)-EIS test, the crucial features of TR were extracted using the RReliefF algorithm. TR mechanisms corresponding to the features at specific frequencies were analyzed. Finally, a three-level warning strategy for single battery, series module, and parallel module was formulated, which can successfully send out an early warning signal ahead of the self-heating temperature of battery under thermal abuse condition. The technology can provide a reliable basis for the timely intervention of battery thermal management and fire protection systems and is expected to be applied to electric vehicles and energy storage devices to realize early warning and improve battery safety.