In this work, a Li-rich layered Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2 cathode material synthesized by a coprecipitation method is further treated by NH 4 F. Material characterizations and electrochemical measurements show that the surface modification leads to a phase transition from the original layered phase to a spinel-like phase at the particle surface. It is found that the rate capability and cyclability of Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2 can be significantly improved, which could be attributed to the locally transformed spinel-like structure and F- ion doping at the particle surface, which favor fast lithium ion diffusion and structural stability.