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 Li2IrO3 upon electrochemical cycling. It is found that Li2IrO3 undergoes phase transition and slight capacity fading at each cycle. All the thermodynamically stable phases of Li2-xIrO3 (0≤x<2) are identified through a complete structural screening based on electrostatic energy and DFT calculations, and compared with Transmission Electron Microscopy (TEM) and X-ray Diffraction (XRD) experiments. Core Level Spectroscopy is adopted to probe the changes in the oxygen electronic structure at various (de)lithiation stages, and corresponding oxygen K-edge spectra are simulated based on first-principles calculations. The cationic/anionic charge compensation mechanism of Li2IrO3 upon delithiation, as well as its resistance to O2 loss are discussed based on the spectroscopic observations.
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