Stabilizing the cycling capability of LiFe0.5Mn0.5PO4 by carbon encapsulation for lithium-ion batteries

Abstract

Olivine LiFe_0.5Mn_0.5PO₄ is a promising cathode material for lithium-ion batteries owing to its excellent structural stability and high operating voltage. However, its intrinsically low electronic conductivity and Mn dissolution severely limited its large-scale applications. Herein, an L-tartaric-acid-assisted carbon coating strategy is developed to fabricate carbon-coated LiFe_0.5Mn_0.5PO₄ by a facile rheological phase reaction method. Density functional theory calculations combined with electrochemical analyses reveal that the –COOH and –OH groups of L-tartaric acid would promote strong interfacial interactions with LiFe_0.5Mn_0.5PO₄ and facilitate the formation of a uniform and continuous carbon coating on the matrix, thereby accelerating charge-transfer and inhibiting Mn dissolution. As a result, the optimized LFMP-0.5 delivers a high specific capacity of 158.7 mAh/g at 0.1C and improved cycling stability, maintaining a capacity retention rate of 95.97% after 500 cycles at 1C. This work demonstrates an effective and scalable carbon coating strategy for improving olivine phosphate cathodes and provides new insights into the rational design of high-performance lithium-ion batteries.