Simple synthesis of a hierarchical LiMn0.8Fe0.2PO4/C cathode by investigation of iron sources for lithium-ion batteries

Abstract

Iron (Fe) substitution is an effective strategy for improving the electrochemical performance of LiMnPO₄ which has poor conductivity. Herein, we focus on investigating the effect of substitution of Mn with different iron sources, on the structure and electrochemical performances of the LiMnPO₄ materials. The Fe-substituted LiMnPO₄/C composites were synthesized via a simple and rational solid-state method, and will be of benefit for engineering applications. The characterization of the materials shows an obvious influence of the iron sources on structure and morphology. The N-LMFP material prepared using soluble FeNO₃ as iron sources exhibits an excellent rate capacity of 122 mA h g⁻¹ at 5C, and superior cyclability with a capacity retention of 98.9% after 400 cycles at 2C. The enhanced rate capability and cycling stability of N-LMFP are the result of the lowered electron/ion resistance and the improved reversibility of the reaction, that originates from the homogeneous fine particles and hierarchical structure with large mesopores. This research provides significant guidelines for designing an LiMnPO₄ cathode with a high performance.