Thermal stability of lithium-ion battery subjected to inhomogeneous aging

Aged battery is prone to fire accidents. Thermal stability change of battery subjected to inhomogeneous aging is studied in this manuscript by accelerating rate calorimeter. The results indicate that thermal runaway time decreases for aged batteries. Solid electrolyte interphase and lithium plating suppress and accelerate onset exothermic side reactions. Transition metal dissolution accelerates positive electrode decomposition and oxygen release. T_TR of aged batteries decreases compared to fresh battery. Microscopic changes of negative electrodes for batteries cycled at high and low temperature are inhomogeneous. T_onset for batteries cycled at low temperature decreases as lithium plating covers all of the negative electrode surface. T_onset for batteries cycled at high temperature and with 100% state of charge (SOC) increases. This is the same to battery stored at high temperature. Local lithium plating affects thermal stability of battery with 100% SOC less. However, T_onset for batteries with SOC lower than 50% SOC and subjected to local lithium plating decreases compared to fresh battery. Local lithium plating accelerates onset exothermic side reactions for battery with SOC lower than 50% SOC. The results of this manuscript are important to thermal runaway prevention for batteries in their whole operation life.