通过流变相法合成LiNi0.4Co0.2Mn0.4O2材料,用MgF2包覆对其进行表面修饰改性,来改善高温、高倍率下的循环稳定性。利用X射线衍射仪、扫描电子显微镜和充放电测试技术研究MgF2包覆对正极材料的晶体结构、微观形貌和电化学性能的影响。电化学性能测试结果表明,当MgF2的包覆量为1％时,材料的充放电性能和循环性能最好,初始放电比容量为176.2mAh/g;50次循环后,放电比容量仅降到162.9mAh/g,容量保持率最高,为92.4%,表现出良好的电化学稳定性。这些结果表明,通过对LiNi0.4Co0.2Mn0.4O2表面进行MgF2包覆处理,可以提高材料的电子导电率,减少电极材料与电解液的副反应。MgF2包覆改性使三元正极材料的电化学性能有一定程度的提高。
LiNi0.4Co0.2Mn0.4O2 material was synthesized by flow phase method,and the surface modification of LiNi0.4Co0.2Mn0.4O2 was carried out with MgF2 coating,so as to improve the cyclic stability at high temperature and high rate.The influence of MgF2 coating on the crystal structure,microstructure and electrochemical properties of the materials was studied by X-ray diffractometer,scanning electron microscope and charge-discharge test.Electrochemical performance test results shown that:when the MgF2 coating amount was 1%,the charging and discharging performance and cycling performance were all the best,the initial discharge capacity was 176.2mAh/g.After 50 cycles,the discharge capacity was only reduced to 162.9mAh/g.The capacity retention rate was the highest of 92.4%,showing good electrochemical stability.These results shown that MgF2 coating on LiNi0.4Co0.2Mn0.4O2 can improve the electronic conductivity of the material,and reduced the side reaction between the electrode material and the electrolyte.The electrochemical properties of the materials were improved to a certain extent by MgF2 coating modification.
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