Low-temperature heat treatment enhances the structural stability of O2-type lithium-rich manganese-based materials

Abstract

Lithium-rich manganese-based cathode materials offer both high capacity and low cost. However, the O2 phase obtained by ionexchange methods is prone to instability in practical applications. Therefore, we systematically investigated the phase-structure evolution and electrochemical properties of O2-type materials subjected to heat treatments in the range of 200-500 °C. The results indicate that low-temperature heat treatment at 200 °C facilitates lattice rearrangement of the O2 phase and helps maintain phase stability. The electrochemical performance is improved accordingly, with a capacity retention of 60.8% after 500 cycles. In contrast, when the heat-treatment temperature exceeds 400 °C, the O2 phase transforms into an O3 phase, leading to a significant deterioration in capacity and rate capability. This study clarifies the influence of heat-treatment temperature on the structure and performance of O2-type lithium-rich manganese-based cathode materials and provides a theoretical basis for their optimization and application.