Abstract: A hydrothermal reaction has been adopted to synthesize LiFePO₄ precursor firstly.Then it was modified with carbon coating and magnesium ion（Mg²⁺） doping through a post-heat treatment.The chemical composition，morphology，and structure of the material were characterized by X-ray diffraction（XRD），scanning electron microscopy（SEM），and transmission elec- tron microscopy（TEM）.Energy dispersive spectroscopy mappings have verified the homogeneous existence of doped Mg²⁺ in LiFePO₄ particles.The electrochemical performances of the as-prepared material were studied by galvanostatic charging/dis- charging measurements，cyclic voltammetry（CV），and electrochemical impedance spectroscopy（EIS）.The test results showed that Mg²⁺ doped lithium iron phosphate exhibited high special capacity（160.1 mA·h/g at 0.1C），superior rate capability （77.2 mA·h/g at 20C），and could reduce the polarization and decrease charge transfer resistance.This synthesis route is promising in making the hydrothermal method more practical for preparation of the LiFePO₄ material and enhancement of electrochemical performance.

Key words: hydrothermal reaction, LiFePO₄, Mg²⁺ adoping, electrochemical performance