Numerical modeling of thermal runaway for low temperature cycling lithium-ion batteries

Thermal runaway is still recognized as one of the most important hazards of lithium-ion batteries (LIBs), which prevents the application of LIBs on electric vehicles and stationary energy storage system. Lithium plating, which is mostly observed in LIBs after low temperature cycling, contributes significantly to not only ageing effect but also deterioration of battery thermal runaway (TR) performance. This study developed a thermal runaway model for low-temperature cycling LIBs, in which an exothermic reaction between metal lithium and electrolyte was introduced into the thermal abuse reactions to take the ageing effect into account. Hot oven abuse tests were conducted to validate the model. It was found that the TR process can be divided into three stages according to the variations of cell voltage. The simulations of hot oven abuse tests showed that for low temperature cycling cells, the reaction between plated lithium and electrolyte occurred at around 140 degrees C, which promoted the re-actions and led to an earlier start of TR. Heat generation from the reaction of each component was quantified based on the simulations. The results showed that the total heat generations during TR increased only a little with ageing. The positive-electrolyte reaction was the largest heat source and the negative-electrolyte reaction was the second. Heat generation from the deposited Li-electrolyte reaction increased with the ageing of cells. This work helps to understand the TR mechanism of aged LIBs and successfully predicts the TR behaviors of low -temperature cycling cells.