P2-type Na0.8(Li0.33Mn0.67-xTix)O2 doped by Ti as cathode materials for high performance sodium-ion batteries

Ti substituted P2-phase Na0.8(Li0.33Mn0.67-xTix)O2 (x = 0, 0.05, 0.1 and 0.2) cathodes are synthesized by a simple sol-gel method. The effects of Ti substitution on the crystal structure, morphology and electrochemical performances of Na0.8(Li0.33Mn0.67-xTix)O2 are also analyzed. Combining the advantages of smaller particle size, enhanced structural stability and higher Na+ diffusion rate, the sample for x = 0.1 exhibits a high initial coulombic efficiency of 87.8%, good cyclic stability of 121 mA h g−1 after 100 cycles, and an outstanding rate performance of 85 mA h g−1 at 500 mA g−1. These results suggest that Ti substitution can be an effective method to enhance the electrochemical properties of P2-type Na0.8(Li0.33Mn0.67-xTix)O2 cathodes.