有机溶剂醇热法对LiCoO_2正极表面修饰

Surface-modified LiCoO_2 cathode material by organic solvent alcohol-heating method

采用有机溶剂醇热法,以异丙醇铝为原材料对LiCoO2进行表面处理。通过XRD、SEM对包覆前后正极材料的微观结构进行表征,对包覆前后正极材料的电化学性能进行测试。结果表明:包覆后正极材料的充放电效率明显提高,循环30次后容量保持率由包覆前的84.1%提高到包覆后的93.2%。这归因于包覆后LiCoO2表面形成的Al2O3或LiAlxCo1-xO2层,该层起到阻挡层的作用,有效地抑制Co4+与电解液反应,稳定了LiCoO2结构,提高了电化学循环性能。

The organic solvent alcohol-heating method was used to modify LiCoO_2 cathode material's surface with aluminium isopropoxide. The structures of surface-modified LiCoO_2 cathode material were characterized with X-ray diffraction(XRD) and scanning electron microscope(SEM).The electrochemical measurement results show that the charge/discharge efficiency of coated LiCoO_2 is improved significantly and the capacity retention is increased from 84.1% to 93.2% after 30 cycle times. The improvements are attributed to the Al_2O_3 or solid solution LiAl_xCo_(1-x)O_2 layer on the LiCoO_2 surface. The coating layer is effective in stopping reactions of Co^(4+) ions with electrolyte, and stabilizes the structure of LiCoO_2, so improving the electrochemical cycle performance.