The elevated temperature performance of LiMn2O4 coated with LiNi1−XCoXO2 (X = 0.2 and 1)

The surface coating of LiMn2O4 using a gel precursor of LiNi1−XCoXO2 (X=0.2 and 1) prepared from a solution-based chemical process was attempted in order to enhance the electrochemical performances of LiMn2O4 at elevated temperature. After the surface of LiMn2O4 was coated with LiNi1−XCoXO2 (X=0.2 and 1) coating solution and heated at 750 °C, the surface of LiMn2O4 was covered with fine LiNi1−XCoXO2 (X=0.2 and 1) particles. LiNi1−XCoXO2 (X=0.2 and 1)-coated LiMn2O4 showed an excellent capacity retention at 65 °C compared to pure LiMn2O4. While pure LiMn2O4 retained 81% of the initial capacity after storage in the discharged state at 65 °C for 300 h, LiCoO2-coated LiMn2O4 showed no capacity loss. The improvement of storage performance at 65 °C is attributed to the suppression of electrolyte decomposition and the reduction of Mn dissolution resulting from encapsulating the surface of LiMn2O4 with LiCoO2. The surface coating with LiNi0.8Co0.2O2 also enhanced the high temperature cycle performance of LiMn2O4. Consequently, It is proposed that the surface encapsulation of LiMn2O4 with fine LiNi1−XCoXO2 (X=0.2 and 1) particles improve its high temperature performance.