Elucidating Structural, Morphological and Chemical Evolutions of the Electrodes in the NMC532 Automotive batteries

Abstract The Li[Ni 0.5 Co 0.2 Mn 0.3 ]O 2 (NCM) battery is widely used in new energy vehicles, however, the battery lifespan and safety issues have become key constraints. It is necessary to explore the aging characteristics and mechanism of NCM batteries. Therefore, in this study, degradation mechanism of the NCM532 lithium ion batteries with nominal capacity of 114Ah under different aging states and operational conditions are analyzed. Disassembly methods are employed to analyze the crystal structure, morphology, and elemental composition of cathode, anode, and separator materials. It is found that after battery aging, particle fragmentation of cathode and anode materials, thickening of the solid electrolyte interphase (SEI) film on the anode, and generation of side reaction products from the electrolyte occur. Meanwhile, half cell tests demonstrated good capacity retention of the cathode but significant capacity loss of the anode. The study reveals the battery degradation mechanism affected by temperature, rate, and SOC range, providing experimental support for optimizing the lifespan of NCM lithium ion batteries.