Effect of F-Doping on the Cycling and Structural Stability of li[Li0.2Mn0.534 Ni0.133Co0.133]O2 Cathode for Li-Ion Batteries

In recent studies, the layered composites with Li₂MnO₃ and LiMO₂ have become as the promising cathode materials for lithium ion batteries due to the high capacity of around 250 mAh/g with a lower cost and better safety in comparison with LiCoO₂.

In this study, a PAAM(Polyacrylamide)-assisted carbonate co-precipitation method was attempted to prepare the spherical Li[Li_0.2Mn_0.534 Ni_0.133Co_0.133]O₂ cathode material. With the F-doping, the particle size of Li[Li_0.2Mn_0.534 Ni_0.133Co_0.133]O_1.95F_0.05 decreased, which was beneficial for the electrochemical properties. After 80cycles at 0.05C, the capacity was 259 mAh/g and the retention was 90% for Li[Li_0.2Mn_0.534 Ni_0.133Co_0.133]O_1.95F_0.05. After 200 cycles at 0.1C, 0.2C and 0.3C, the retention was 94%, 93% and 95%, respectively. The cycling properties was improved obviously with F-doping. From the results of synchrotron radiation XRD, the structures were changed with the temperature from the ambient temperature to 500 °C for Li[Li_0.2Mn_0.534 Ni_0.133Co_0.133]O₂. But no structural changes were observed for Li[Li_0.2Mn_0.534 Ni_0.133Co_0.133]O_1.95F_0.05. Hence, the structural stability was improved further with F-doping.