Aging Mechanisms and Evolution Patterns of Commercial LiFePO4 Lithium-Ion Batteries

It is crucial to fully understand the degradation law of commercial LiFePO4 lithium-ion batteries (LIBs) in terms of their health and safety status under different operating conditions, as well as the degradation mechanism and influencing factors. This work investigates the evolution patterns of cycling performance in commercial LiFePO4 batteries under different operating conditions, including temperature, electrolyte, charge/discharge rate, and depth of cycling. Structure characterization tests on electrode materials before and after long-term cycles have been carried out to elucidate the failure/degradation mechanisms during battery operation. It has been found that it is a comprehensive effect from different operation conditions that results in performance degradation. Fe element shuttling and Li deposition may cause internal decay of LiFePO4 LIBs. Additionally, working temperatures and the rate and depth of discharge (DOD) should be strictly controlled to achieve high energy retention and long life. This study proposes a perspective that explores the impact of internal and external factors on the degradation of the safety performance in LiFePO4 LIBs, with the aim of improving the safe and stable operation of large-scale LiFePO4 LIB energy storage systems, as it is favorable to unravel their complex multi-dimensional evolution mechanism and coupling effects throughout their life cycle.