溶胶-凝胶法制备LiV3-y NbyO8的电化学性能

Electrochemical performance of LiV3-y NbyO8 prepared by sol-gel method

采用溶胶-凝胶法制备LiV 3-y Nb y O 8(y=0、0.03、0.06和0.09)正极材料。通过XRD、SEM和电化学性能测试,研究材料的结构、形貌和电化学性能。Nb掺杂不改变钒酸锂(LiV 3O 8)的单斜层状结构,但可增大晶胞体积,掺杂后仍为亚微米颗粒。当y=0.06时,电化学性能最好,在1.8~4.0 V循环具有良好的倍率性能,电流为0.1 A/g、5.0 A/g时的放电比容量分别为396.5 mAh/g、124.9 mAh/g。电化学性能改善的主要原因是:Nb掺杂提高了材料的Li+扩散系数,降低了电荷间的转移电阻。

LiV3-y NbyO8(y=0,0.03,0.06 and 0.09)cathode materials were prepared by sol-gel method.The structure,morphology and electrochemical performance of the material were studied by XRD,SEM and electrochemical performance test.The monoclinic structure of lithium vanadium oxide(LiV 3O 8)was not changed by Nb doping,but the cell volume was increased,it was still submicron partical after doping.Wheny=0.06,the electrochemical performance was the best.When cycled in 1.8-4.0 V,its specific discharge capacity was 396.5 mAh/g and 124.9 mAh/g at the current of 0.1 A/g and 5.0 A/g,respectively,which showed fine rate capability.The improving of electrochemical performance mainly resulted from the improving of diffusion coefficient of Li+and reducing of the transfer resistance between charges for Nb doping.