Improved Cycling Stability of Cobalt-free Li-rich Oxides with a Stable Interface by Dual Doping

Li-rich cobalt-free oxides, popularly used as a cathode with high capacity in lithium ion battery, always suffer from poor cycling stability between 2.0 and 4.8 V vs Li+/Li, especially when cycled at high temperatures (>50 °C). To overcome this issue, Na+ and Al3+ dual-doped NaxLi1.2-xMn0.6-xAlxNi0.2O2 Li-rich cathode is prepared in this study. It is shown that the side reactions between cathode and electrolyte during cycling are suppressed. The improved cycling performance is observed for all of the doped samples, among which the sample with x = 0.03 exhibits the highest capacity retention of 86.1% after 200 cycles between 2.0 and 4.8 V at 2C (1C = 200 mA g−1) and shows a remarkable cycling stability, even at a high temperature of 55 °C (a capacity retention of 92.2% after 100 cycles). Moreover, the average voltage of the sample with x = 0.03 after 100 cycles at 0.5C remains at 3.11 V with a retention ratio of 86.6%. This work provides a new strategy to develop Li-rich cobalt-free cathodes with excellent cycling stability for lithium ion batteries at high temperatures.