High-performance LiMn_1-xFe_xPO₄/C cathodes constructed using a nano-sized spherical MnFePO₄·H₂O precursor via a...

To develop high-safety and high-performance olivine LiMn_1-xFe_xPO₄/C cathodes for lithium-ion batteries, a scalable synthetic route is established by employing KMnO₄ as the oxidant to prepare the MnFePO₄·H₂O precursor through a reverse-titration co-precipitation strategy. Nanosized spherical MnFePO₄·H₂O with a uniform elemental distribution and consistent valence states is successfully obtained, effectively suppressing Mn³⁺ disproportionation in an aqueous co-precipitation system. During lithiation, Li⁺ inserts into the initially vacant M1 sites, accompanied by the reduction of Mn³⁺/Fe³⁺ to Mn²⁺/Fe²⁺, thereby converting trivalent MnFePO₄·H₂O into olivine LiMn_1-xFe_xPO₄. The sand-milling spray-drying (SMSD) process further enables the formation of quasi-spherical secondary particles with a narrow particle-size distribution and a continuous highly graphitized carbon coating layer, in clear contrast to the irregular agglomerates and nonuniform carbon coatings generated by conventional ball-milling/stirring-drying treatment. As a result, the L-SMSD sample delivers a high discharge specific capacity of 153.5 mAh g^-1 at 0.1C, an excellent rate capacity of 120.5 mAh g^-1 at 5C, and outstanding cycling stability with a capacity retention of 95.15% after 450 cycles at 1C. Kinetic analysis further reveals that L-SMSD exhibits reduced polarization, enhanced Li⁺ diffusivity, and improved interfacial reaction kinetics. This work provides a practical route for the industrial-scale production of LiMn_1-xFe_xPO₄/C cathodes and is of great significance for the development of next-generation lithium-ion batteries.