正极材料LiNi0.4Co0.2Mn0.4O2阴离子掺杂改性研究

采用溶胶-凝胶法合成了层状LiNi0.4Co0.2Mn0.4O1.97X0.03(X=O,F,Cl)正极材料。以XRD、SEM、CV、EIS和充放电测试等手段对材料的晶体结构、表观形貌和电化学性能进行表征。XRD结果显示F-和Cl-掺杂没有改变晶体的六方单层状结构;CV结果表明掺杂提高了材料的可逆性;充放电测试表明,F-和Cl-掺杂均提高了材料的放电容量,并改善了材料的循环性能;EIS测试结果发现,F-和Cl-掺杂均有效地抑制其在循环过程中电化学反应阻抗的增加。

Anion Doping of LiNi0.4Co0.2Mn0.4O2 Cathode Material for Lithium-Ion Batteries

The layered LiNi0.4Co0.2Mn0.4O1.97X0.03 (X=O, F, Cl) samples were prepared by a sol-gel method. The crystal structure, apparent morphology and electrochemical performance were characterized by XRD, SEM, cyclic voltammograms (CV), electrochemical impedance spectroscopy (EIS) and charge-discharge tests. The results show that LiNi0.4Co0.2Mn0.4O1.97X0.03 (X=O, F, Cl) samples remain a well-layered structure with single phase of hexagonal after fluorine or chlorine doping. The reversibility of the cathode materials is enhanced by fluorine or chlorine doping. The discharge capacity is increased and cycling property improved. The increase of electrochemical reaction impedance of cathode is restrained after fluorine or chlorine doping during cycling.