Correlation between the Cation Disorders of Fe3+ and Li+ in P3-Type Na0.67[Li0.1(Fe0.5Mn0.5)0.9]O2 for Sodium Ion Batteries

Various Fe-based layered oxide materials have received attention as promising cathode materials for sodium ion batteries because of their low cost and high specific capacity. Only a few P3-type Fe-based oxide materials, however, have been examined as cathodes because the synthesis of highly crystalline P3-type Fe-based oxides is not facile. For this reason, the structural merits of the P3 structure are not yet fully understood. Herein, highly crystalline P3-type Na 0.67 [Li 0.1 (Fe 0.5 Mn 0.5 ) 0.9 ]O 2 heated at 900 °C is introduced to improve the electrochemical performance of Fe-based layered oxides. The structures, reaction mechanisms, and electrochemical performances of P3 Na 0.67 [Li 0.1 (Fe 0.5 Mn 0.5 ) 0.9 ]O 2, P2 Na 0.57 [Li 0.1 (Fe 0.5 Mn 0.5 ) 0.9 ]O 2, and P2 Na 0.67 [Fe 0.5 Mn 0.5 ]O 2 are compared to demonstrate the roles of Li + doping in the improved electrochemical perf…