Abstract:

Compared with commercial Li-ion cathode materials (LiCoO₂, LiFePO₄, NMC111, etc.), Li-rich Mn-based cathode materials (LMR-NMCs) possess higher capacities of more than 250 mAh g^-1 and have attracted great interest from researchers as promising candidates for long-endurance electric vehicles. However, unsolved problems need to be addressed before commercialization with one being voltage decay during cycling. Here, researchers have proposed that the mechanisms of voltage decay in Li-rich Mn-based cathode materials involve factors such as surface phase transformation, anion redox and oxygen release and have found evidence of transition metal-migration, microstructural defects caused by LMR and other phenomena using advanced characterization techniques. As a result, many studies have been conducted to resolve voltage decay in LMR-NMCs for practical application. Based on this, this article will systematically review the progress in the study of voltage decay mechanisms in LMR materials and provide suggestions for further research.

Full-text：https://link.springer.com/article/10.1007/s41918-019-00049-z

Key words: Voltage decay, Surface phase transformation, TM migration, Anion redox, Microstructural defects, Voltage hysteresis