Improved electrochemical performance of LiNi0.6Co0.2Mn0.2O2 cathode material synthesized by citric acid assisted sol-gel method for lithium ion batteries

Abstract A citric acid assisted sol-gel method is employed for synthesizing LiNi 0.6 Co 0.2 Mn 0.2 O 2 for use as a cathode material in lithium-ion batteries. The effects of heat-treatment temperature and oxygen atmosphere on the structural and electrochemical properties of LiNi 0.6 Co 0.2 Mn 0.2 O 2 are investigated, in order to determine optimal conditions for the synthesis of LiNi 0.6 Co 0.2 Mn 0.2 O 2 via the citric acid assisted sol-gel method. In particular, the presence of oxygen in the atmosphere effectively leads to a decrease in the degree of cation mixing and the formation of LiOH and Li 2 CO 3 on the surface of LiNi 0.6 Co 0.2 Mn 0.2 O 2 . Furthermore, heat-treatment in an oxygen atmosphere improves the uniformity of oxidation state of Ni ions between the surface and bulk. LiNi 0.6 Co 0.2 Mn 0.2 O 2 synthesized by heat-treatment at 850 °C under an oxygen atmosphere shows a discharge capacity of 174 mA h g −1 and 89% capacity retention after 100 cycles. In addition, it shows high rate capability (i.e., 41% capacity retention at 10 C), which is an improved rate performance over a previous report. The results of this study should provide useful information for the synthesis of Ni-rich layered oxides for lithium ion batteries.