Understanding the construction of nano-structured LiMnFePO by a co-precipitation strategy and Mg doping towards high-performance lithium-ion batteries.

LiMnFePO has attracted wide attention due to its higher voltage platform and energy density without sacrificing several excellent properties of pure LiFePO. However, the conventional co-precipitation route for preparing LiFePO is not applicable to LiMnFePO. In this paper, nano-structured LiMnFePO/C microspheres with high dispersibility and high compaction density are synthesized by using NHMnFePO·HO obtained a co-precipitation strategy as a precursor for the first time, which enables Mn, Fe and P to be uniformly deposited. Furthermore, the Mg doping strategy is also carried out to optimize the electrochemical performance. Our results show that the introduction of Mg can alleviate the lattice expansion and deformation caused by the Jahn-Teller effect, improving the structural stability of LiMnFeMgPO/C. Meanwhile, the diffusion kinetics are investigated by electrochemical impedance spectroscopy and cyclic voltammetry, revealing that Mg doping effectively reduces the interfacial resistance and increases the lithium-ion diffusion coefficient. As a result, the LiMnFeMgPO/C cathode exhibits superior rate performance, delivering capacities of 150.1, 141.4 and 111.6 mAh g at 0.1, 1 and 5C, respectively. This work provides important guidance for the industrial-scale manufacturing and practical application of LiMnFePO/C, which is conducive to its further development.