Green Phytic Acid-Assisted Synthesis of LiMn_1−xFe_xPO₄/C Cathodes for High-Performance Lithium-Ion Batteries

As a promising cathode material, olivine-structured LiMnPO₄ holds enormous potential for lithium-ion batteries. Herein, we demonstrate a green biomass-derived phytic-acid-assisted method to synthesize a series of LiMn_1−xFe_xPO₄/C composites. The effect of Fe doping on the crystal structure and morphology of LiMnPO₄ particles is investigated. It is revealed that the optimal Fe doping amount of x = 0.2 enables a substantial enhancement of interfacial charge transfer ability and Li⁺ ion diffusion kinetics. Consequently, a large reversible capacity output of 146 mAh g⁻¹ at 0.05 C and a high rate capacity of 77 mAh g⁻¹ at 2 C were acquired by the as-optimized LiMn_0.8Fe_0.2PO₄/C cathode. Moreover, the LiMn_0.8Fe_0.2PO₄/C delivered a specific capacity of 68 mAh g⁻¹ at 2 C after 500 cycles, with a capacity retention of 88.4%. This work will unveil a green synthesis route for advancing phosphate cathode materials toward practical implementation.