The mechanism of the impact of Li2MnO3 with dual-edged sword functionality on the cyclic performance of lithium-rich manganese-based cathode materials

The Li 2 MnO 3 phase is a double-edged sword hanging over lithium-rich manganese-based cathode materials (LLOs). It provides a theoretical specific capacity of over 300mAh/g for LLOs, but it is also the main source of issues such as low Initial Coulombic efficiency (ICE), poor rate performance, and voltage decay. In recent years, related research has primarily focused on the lattice oxygen. From the perspective related to the Li 2 MnO 3 phase, this study achieves different activation degrees of Li 2 MnO 3 phase through ingenious electrochemical methods . It conducts a detailed analysis of the phase transition and polarization of Li 2 MnO 3 phase under high and low rates, and delves into the different mechanisms that cause the electrochemical performance degradation of LLOs under high and low rates. The results show that during low-rate cycling, the more Li 2 MnO 3 phase in LLOs, the more transformation of crystal structure from layered to spinel phase occurs during cycling, and the structural transformation of the material will ultimately lead to the degradation of cycle performance and voltage decay. During high-rate cycling, due to the intrinsic conductivity difference of Li 2 MnO 3 phase, the large polarization effect of LLOs can lead to severe decomposition of the electrolyte at high voltages, resulting in the degradation of cycle performance. Therefore, conducting research on LLOs focused on the Li 2 MnO 3 phase may be an effective approach, providing a new modification idea for achieving more excellent cycling performance of LLOs.