Effect of Zn Doping on the Structure and Electrochemical Performance of LiNi1/3Co1/3Mn1/3O2

LiNi1/3Co1/3-xMn1/3ZnxO2 (x=0, 1/24, 2/24 and 4/24) cathode material for lithium-ion battery was synthesized by a sol-gel method. The results of XRD and SEM show that Zn doping does not change the alpha-NaFeO2 layer structure of LiNi1/3Co1/3Mn1/3O2, and impurity phases occur when the doped amount reaches 4/24. Electrochemical studies indicate that when the doped Zn content is 2/24, the initial discharge capacity of LiNi1/3Co1/3Mn1/3O2 decreases from 169.2 mAh.g(-1) of the undoped material to 160.1 mAh.g(-1). The cycling performance, however, is significantly improved. Compared with undoped material, the capacity retention rate of the sample of LiNi1/3Co1/3-xMn1/3ZnxO2 with x=2/24 increases from 89.2% to 97% after 30 cycles. The same sample was charged and discharged again at 20 mA.g(-1) and the corresponding discharge specific capacity was restored to 150.3 mAh.g(-1) after 20 cycles in different current densities of 20, 40, 60 and 80 mA.g(-1).