Unravelling the Influence of Synthetic Paths on the Cation Arrangement in Lithium-rich Layered Oxide Cathode Materials

Abstract

• The strategy for adjusting the cation arrangement of the Li-rich cathode materials was proposed by simply adjusting the mixing order of cations in the sol-gel synthesis. • The results further prove that improving the order arrangement of cations can effectively ameliorate the stability and electrochemical performance of the Li-rich materials. • The optimized Li-rich materials exhibit a good cycle performance with a capacity retention of 71.7% after 150 cycles, much better than that of the pristine sample with a retention of only 45.5%. Lithium-rich layered oxides (LLOs) have garnered substantial attention due to their superior reversible capacity. However, oxygen release and transition metal migration are likely to occur during the charging and discharging process because of the inherently unstable structure of LLOs, which hampers their commercialization process. Present studies suggest that the local structure and atomic arrangement have a considerable impact on the stability of LLOs. Hence, researchers have been trying to determine how to implement the control of atomic ordering. Herein, we propose a new strategy to modify the cation arrangement of LLOs by adjusting the mixing order of cations through the sol-gel method. As a result, the optimized S-LLO sample presents a more ordered cation arrangement than that of the pristine M-LLO sample. The S-LLO cathode, meanwhile, provides a high discharging capacity of 249.5 mAh·g −1 accompanied by a coulombic efficiency of 73.7% at 0.1 C and can still maintain a capacity of 91.8 mAh·g −1 at 10 C. More importantly, a high-capacity retention of 71.7% can be obtained after 150 cycles at 1 C for the optimized LLO cathode, whereas the pristine M-LLO sample retains a retention of only 45.5%. A new strategy to modify the cation arrangements of LLOs by adjusting the mixing order of cations through the sol-gel method.