Structural and Chemical Evolution of Li-Rich Li 2 IrO 3 during Electrochemical Cycling

In the pursuit of novel cathode materials with high Li capacities, the Li-rich oxides with Li/TM (transition metal) ratio larger than 1 have recently gained increased interest. For instance, the active role of oxygen ions in the charge compensation has been reported in layered rocksalt Li 2 IrO 3 , 1 which serve as a model system to understand the structural response of Li-rich cathodes to Li extraction, as well the role of oxygen in compensating Li + loss. In this study, we employed various experimental techniques as well as first-principles density functional theory (DFT) to investigate the structural and electronic evolution of Li 2 IrO 3 upon electrochemical cycling. It is found that Li 2 IrO 3 undergoes phase transition and slight capacity fading at each cycle. All the thermodynamically stable phases of Li 2-x IrO 3 (0≤x