High-performance lithium-ion cathode LiMn_0.7Fe _0.3PO₄/C and the mechanism of performance enhancements through fe substitution

LiMn_1-xFe_xPO₄/C (x = 0 and 0.3) with a uniform carbon coating and interspersed carbon particles was prepared by a high-energy ball-milling (HEBM)-assisted solid-state reaction. The as-synthesized LiMn_0.7Fe_0.3PO₄/C delivered an excellent rate performance as a LiMnPO₄ class of materials. Specifically, the specific discharge capacity was 164 mAh/g (96% of theoretical value) at the 0.05 C rate and 107 mAh/g at the 5 C rate (1 C = 170 mA/g). Electrochemical impedance spectroscopy (EIS) and galvanostatic intermittent titration technique (GITT) measurements indicated improvements in the transport of electrons and Li⁺ as well as the emergence of a single-phase region in lithium extraction and insertion reactions.