Safety of Lithium-Ion Cells and Batteries at Different States-of-Charge

Lithium-ion cells and batteries pose safety risks along with their favorable characteristics such as high energy and power densities. The numerous differences in chemistries and form-factors along with poor manufacturing quality in some cases, can lead to unpredictable field failures with this battery chemistry. The safety of lithium-ion cells and batteries at various states of charge (SOC) has not been studied comprehensively in the past and the goal of this study was to determine if the result of off-nominal conditions would vary with SOC. The study includes cells and batteries of different form factors, cathode chemistries, and capacities. The off-nominal conditions that the cells were exposed to were high-temperature and low impedance external short. In addition to this, voltage stability for the cells and batteries at various SOC was studied for a period of 9 months. The results demonstrate the differences in the level of safety for the cells and batteries at different SOC.