Identifying battery aging mechanisms in large format Li ion cells

Large format LiFePO4-based Li-ion batteries are rapidly becoming available from commercial cell manufacturers. In this paper two types of 10 Ah single cells (one prismatic and another cylindrical) from two manufacturers were tested at room temperature and 60 °C. Both cells suffered severe degradation at 60 °C. The results were analyzed using incremental capacity analysis (ICA) along with other electrochemical techniques. Overall the two types of cells were similar in behavior, despite subtle differences in performance. This study shed some light on the degradation process associated with these two large format LiFePO4 cell designs with regard to thermal degradation at elevated temperatures. The analysis illustrates a unique capability of using ICA to differentiate cell performance and material utilization in different cell designs.