Probing Electrochemically-Induced Structural Evolution and Oxygen Redox Reactions in Layered Lithium Iridate

In order to exploit electrochemical capacity beyond the traditionally-utilized transition metal redox reactions in lithium-metal-oxide cathode materials, it is necessary to understand the role that oxygen ions play in the charge compensation mechanisms, i.e., to know the conditions triggering electron transfer on the oxygen ions and whether this transfer is correlated with battery capacity. Theoretical and experimental investigations of a model cathode material, Li-rich layered Li2IrO3, have been performed to study the structural and electronic changes induced by electrochemical delithiation in a lithium-ion cell. First-principles density functional theory (DFT) calculations were used to compute the voltage profile of a Li/Li2-xIrO3 cell at various states of charge, and the results were in excellent agreement with electrochemical data. Electron energy loss spectroscopy (EELS), X-ray absorption near-edge spectroscopy (XANES), resonant/non-resonant X-ray emission spectroscopy (XES), and first-principles cor...