高嵌锂电位正极材料LiMn_(1-x)Mg_xPO_4/C结构与电化学性能研究

Study on structure and electrochemical properties of LiMn_(1-x)Mg_xPO_4/C anode material with high intercalation potential

采用高温固相法制备了LiMn1-xMgxPO4/C(x=0.01、,0.02、,0.03、,0.04、,0.05)系列材料,通过XRD,SEM,恒流充放电和交流阻抗等测试方法,研究了镁掺杂量对材料的结构、形貌和电化学性能的影响。结果表明:不同镁掺杂量的LiMn1-xMgxPO4/C材料的结构和形貌未发生明显的变化,Mg2+完全进入材料的晶格,占据Mn位。随着镁掺杂量的增加,材料的放电比容量呈先增加后下降的趋势,则循环稳定性的变化没有明显的规律性。LiMn0.98Mg0.02PO4/C材料0.05C放电比容量为100mAh/g,30次循环后,容量保持率为73%,而0.2C的容量保持率仅为52.43%。

A series of LiMn1-xMgxPO4/C（x=0.01、,0.02、,0.03、,0.04、,0.05）materials were synthesized by high temperature solid phase method.The ifluence of magnesium concentration on the structure,morphology and electrochemical performances of the material was studied by X-ray diffraction（XRD）,scanning electron microscope（SEM）,constant current charge-discharge and electrochemical impedance spectroscopy（EIS）tests.The results showed the structure and morphology of LiMn1-xMgxPO4/C did not change obviously with different magnesium doping amount.Mg2＋got into the lattice fully which occupied Mn position.With increasing magnesium doping amount,discharge specific capacity of these materials increased first and then decreased,there was not distinct regularity in cycle stability.LiMn0.98Mg0.02PO4/C material discharge specific capacity reached 100mAh/g at 0.05C.After 30cycles,the capacity retention rate was 73%,while its capacity retention rate was only 52.43%at 0.2C.