Highly miscible phases in lithium rich manganese-based cathode materials through simple heat treatment control

Li-rich Mn-based materials composed of C 2/ m and R -3  m mixed phases are considered to be the most promising cathode materials for lithium-ion batteries because of their extremely high specific capacity. However, these materials suffer from serious problems such as metal element leaching, oxygen release, and capacity decay during the cycling process. Realizing high mixing of two phases at the atomic level is an important measure to improve material stability, but there is a lack of methodological guidance. Here, we reported that adopting segmented calcination during the pre-calcination can regulate the forms and concentration of defects, the ratio of C 2/ m phase to R -3  m phase, and the grain size in the materials, thereby achieving effective control over the phase solubility and structural stability in the Li-rich Mn-based materials. With the same pre-calcination time, the sample that pre-sintered for 4 h in the first stage and 1 h in the second stage exhibited the best miscibility, thereby demonstrating excellent electrochemical performance, with a high reversible specific capacity of 230 mAh·g −1 at 0.1C and an incredible capacity retention of 87.7 % after 500 cycles.