Computational identification of the safety regime of Li-ion battery thermal runaway

Internal short circuit (ISC) and the subsequent electrochemical heat release is frequently a direct cause to trigger Li-ion battery thermal runaway. In this work, a decouple-recombine modeling approach is adopted to reveal the feature of thermal runaway induced by a typical ISC event. The thermal response and chemical kinetic feature of thermal runaway is computationally investigated in a three-dimensional configuration with assigned heat source intensity and duration. The threshold runaway state and the safety regime diagram are identified, corresponding to a pair of critical heat source intensity and critical duration time. Consequently, a safety regime diagram is computationally identified to distinguish the thermal runaway zone and safety zone. Simulation and analysis has been conducted to evaluate the dominant physical-chemical parameters, and the dependence of cathode material during thermal runaway. Meanwhile, the power dissipation during a representative ISC scenario is analyzed, where the local current could be an order of magnitude higher than that for a regular 1C discharge, and the maximum heat release rate is around 1012 W/m3. This heat release is input as source in the thermal runaway simulation, to demonstrate the coupling of the ISC and thermal abuse models. This work provides useful guidance to the fundamental understanding and prediction of thermal runaway phenomena induced by internal short circuit in Li-ion batteries.