Bi和F复合掺杂对LiMn2O4结构及电化学性能的影响

摘要

Spinel LiMn2-xBixO4-yFy(x=0,0.03;y=0,0.05,0.1) were synthesized by solid state reaction.The synthesized materials were characterized by X-ray diffraction,scanning electron microscope,galvanostatic charge-discharge and cyclic voltammetry techniques to study the structure,surface morphology and electrochemical performance.The results show that all the synthesized materials are of pure spinel phase with smooth surface and uniform size.When cycled for 30 times at the charge-discharge rate of 0.2 C,LiMn1.97Bi0.03O3.95F0.05 with the capacity retentions of 90.88%,which is much higher than 86.51% of LiMn2O4.When cycled for 100 times at room temperature and 55℃ at the charge-discharge rate of 1 C,the capacity retention of LiMn1.97Bi0.03O3.95F0.05 are 91.81% and 83.69%,respectively,which are much higher than 78.65% and 71.82% for LiMn2O4.Bi and F co-doping can enhance the stability and cycling behavior of LiMn2O4,especially the cyclability at elevated temperature.%采用固相法合成LiMn2-xBixO4-yFy（x=0,0.03;y=0,0.05,0.1）,通过X-射线衍射、扫描电子显微镜、恒电流充放电及循环伏安等技术分析检测合成材料的结构、形貌及电化学性能。结果表明：合成的LiMn2-xBixO4-yFy均为尖晶石结构,无杂相,颗粒表面光滑,大小均匀。常温下以0.2C倍率循环30次,LiMn1.97Bi0.03O3.95F0.05容量保持率为90.88%,远高于未改性LiMn2O4的86.51%,常温及55℃下以1 C倍率循环100次,LiMn1.97Bi0.03O3.95F0.05容量保持率分别为91.81%和83.69%,高于未改性的78.65%和71.82%。Bi和F复合掺杂提高了材料的稳定性和循环性能,尤其是高温循环性能。