Stepwise ex situ carbon-coated LMFP/C cathodes for high-energy lithium-ion batteries

LiFe _1-x Mn _x PO ₄ has emerged as a promising cathode material for lithium-ion batteries, combining the excellent rate capability of LiFePO ₄ with the high operating voltage of LiMnPO ₄ . However, the extremely low electronic conductivity and lithium-ion diffusion rate of LiMnPO ₄ severely limit its electrochemical activity, which in turn restricts the electrochemical performance of LiFe _1-x Mn _x PO ₄ . In this paper, carbon-coated LiFe _0.3 Mn _0.7 PO ₄ /C porous material was successfully synthesized by co-precipitation followed by secondary calcination, employing a stepwise ex situ carbon coating strategy. Specifically, the LiFe _0.3 Mn _0.7 PO ₄ matrix was prepared by co-precipitation, and the carbon source was introduced for secondary ball milling and calcination to achieve an effective carbon coating. The results of the high-resolution transmission electron microscopy characterization clearly demonstrate that the synthesized material consists of nearly-spherical particles with structural units of approximately 5.68 nm in diameter. The initial discharge specific capacity of the material is 169.4 mAhg ^-1 at a 0.1 C multiplication rate. After 200 cycles at a 1 C multiplication rate, the discharge specific capacity remains at 155.74 mAhg ^-1 , corresponding to a capacity retention rate of 99.77%. The kinetic analysis further confirmed its excellent lithium-ion diffusion capability. This multistage porous LMFP/C has been constructed based on a stepwise synthesis strategy and is stacked with nanoscale spherical particles. This system is expected to be a promising candidate for the development of the next-generation high-performance orthogonal cathode materials for high-capacity lithium-ion batteries.