镁离子掺杂磷酸铁锂的制备及其电化学性能

通过简单水热反应制备磷酸铁锂前驱体，并结合后期热处理过程制备了镁离子掺杂碳包覆的磷酸铁锂正极材料。利用X射线衍射（XRD）、扫描电镜（SEM）和透射电镜（TEM）等表征了镁离子掺杂磷酸铁锂的成分、形貌和结构。元素分布结果证明镁离子均匀掺杂在磷酸铁锂材料中。通过恒流充放电和循环伏安、交流阻抗等方法对材料的电化学性能进行测试。结果表明，镁离子掺杂后的磷酸铁锂材料具有较高的放电比容量（0.1C放电比容量为 160.1 mA·h/g）和优越的倍率性能（20C放电比容量为77.2 mA·h/g），同时减小了极化和电荷迁移电阻。这条合成路线是提高水热法制备磷酸铁锂正极材料电化学性能的有效方法。

Synthesis and electrochemical performance of magnesium ion doped lithium iron phosphate

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.