Cl-doped LiFePO4/C cathode materials were synthesized through a carbothermal reduction route, and the microstructure and electrochemical performances were systematically studied. Cl-doped LiFePO4/C cathode materials presented a high discharge capacity of ∼90mAhg−1 at the rate of 20C (3400mAg−1) at room temperature. Electrochemical impedance spectroscopy and cyclic voltamperometry indicated the optimized electrochemical reaction and Li+ diffusion in the bulk of LiFePO4 due to Cl-doping. The improved Li+ diffusion capability is attributed to the microstructure modification of LiFePO4 via Cl-doping.