Confining oxygen anion to stabilize layered oxide Li1.2Ni0.2Mn0.6O2 via Zr-Al dual doping

Abstract

Lithium-rich manganese-based transition metal oxide Li1.2Ni0.2Mn0.6O2 (LNMO) can achieve high energy density due to the interaction of anionic redox kinetics in Li2MnO3. However, the irreversible release of oxygen and migration of Mn ions during deep de-lithiation disrupts the layer structure of LNMO, leading to a decrease in voltage and capacity. Herein, we confine oxygen anion through Zr and Al co-doping. Combined analysis of structure refinement, XPS and XAS, the co-doped strategy effectively prohibits cation disordering of Li/Ni, inhibits the Jahn-Teller effect and reduces the transition metal (TM) and oxygen hybridization. As a result, the Zr and Al co-doping LNMO sample (ZA-LNMO) possesses a capacity retention of 92% after 100 cycles and 86% after 200 long-term cycles, much higher than the value of the undoped sample (79% for 100 cycles and 58% for 200 cycles). Even at the harsh conditions such as ultra-high current rate (10 C) or high temperature (60 °C), ZA-LNMO also maintains 70% retention after 200 cycles. Our findings provide an insight into the synergistic effect of cation co-doping and help to design layered oxides for future applications.