A simple method was applied to control the morphology of LiMn2O4 and Li1.05Mn1.97Nb0.03O4 in the sintering process by premixing a suitable proportion of acetylene black in the raw material. Both specific discharge capacity and cycling stability of the samples were improved. The results demonstrated that the doped samples showed excellent electrochemical performance at both 25 degrees C and 55 degrees C.