Degradation characteristics investigation for lithium-ion cells with NCA cathode during overcharging

This paper explores the major degradation characteristics of commercial lithium-ion battery cells with nickel --cobalt-aluminum-oxide (NCA) electrode during cyclic overcharging, and proposes non-destructive methods for detecting overcharging degradation failure. The experimental results show that battery capacity drops signifi-cantly with increasing overcharge depth and number of cycles especially during the first three cycles and when the charging termination voltage is set to 5 V. At the same time, the cell overcharge tolerance decreases with the cyclic overcharging. The combination of the electrochemical impedance spectroscopy and the incremental ca-pacity and differential voltage analysis is used to diagnose cell degradation during cyclic overcharging. Three main degradation modes are identified and quantified by extracting characteristic parameters such as internal resistance and peak, valley, and curve position changes of incremental capacity curves. It is concluded that loss of lithium inventory and loss of active materials are the most dominant degradation modes during cyclic over-charging. Besides, the sharp increase of the third peak on incremental capacity curves has been identified as a unique feature of overcharging degradation, which can be used for diagnosing cyclic overcharging-induced degradation for batteries with NCA cathode.

Automated summary

This paper explores the degradation characteristics of lithium-ion battery cells with NCA electrode during cyclic overcharging and proposes non-destructive methods to detect overcharging degradation failure. Experimental results show that battery capacity drops significantly with increasing overcharge depth and number of cycles, especially during the first three cycles and when the charging termination voltage is set to 5V. At the same time, the cell's overcharge tolerance decreases with cyclic overcharging. The combination of electrochemical impedance spectroscopy, incremental capacity analysis, and differential voltage analysis is used to diagnose cell degradation. Three main degradation modes are identified and quantified by analyzing characteristic parameters such as internal resistance and changes in peak, valley, and curve position of incremental capacity curves. It is concluded that loss of lithium inventory and loss of active materials are the dominant degradation modes during cyclic overcharging. Additionally, the sharp increase of the third peak on incremental capacity curves is identified as a unique feature of overcharging degradation, which can be used to diagnose cyclic overcharging-induced degradation in batteries with NCA cathode.