Recovery of High-Voltage Oxygen Redox Activity by Eliminating Residual Oxygen Dimers

High Resolution Image Download MS PowerPoint Slide Oxygen-redox layered oxides are promising electrode materials with the potential for superior energy density; however, their real-world employment is hindered by severe electrochemical irreversibility. The fundamental origin of this irreversibility has been difficult to pinpoint due to the complex evolution of both the structure and redox centers during cycling. Herein, we reveal that oxygen redox irreversibility is governed by the formation and persistence of oxygen dimer states and, for the first time, demonstrate the reversible recovery of the intrinsic high-voltage oxygen redox plateau (∼4.5 V vs Li/Li + ), which is typically lost after initial charge. Our in-depth tracking of oxygen dimer behavior establishes a direct correlation between the recoverability of the high-voltage plateau and the residual concentration of oxygen dimers i…