Cathode materials LiMn 0.5 Fe 0.5 PO 4 /C and LiMnPO 4 /C were synthesized by a high-energy ball-milling assisted sol-gel method. The LiMn 0.5 Fe 0.5 PO 4 consists of nanorods and nanoparticles homogeneously wrapped with highly ordering carbon. The increased Néel-temperature and decreased effective magnetic moment of LiMn 0.5 Fe 0.5 PO 4 /C revealed the microstructure differences from LiMnPO 4 /C. Meanwhile, tiny amount of ferromagnetic impurities is detected in LiMn 0.5 Fe 0.5 PO 4 /C by magnetic tests. The synergetic effects of Fe substitution and carbon coating remarkably improve rate capacity and cyclic stability of LiMn 0.5 Fe 0.5 PO 4 /C. This solid solution delivers initial discharge capacities of 128.6 mAh g −1 and 116.3 mAh g −1 and capacity retentions of 93.5% and 90.3% after 100 cycles at 1C and 2C respectively, significantly better than LiMnPO 4 /C.