A prismatic alkali-ion environment suppresses plateau hysteresis in lattice oxygen redox reactions

Abstract

Voltage hysteresis is the toughest challenge that hampers the development of lattice oxygen redox (LOR) in high-energy-density positive electrodes. Identifying the decisive factor in the voltage hysteresis of LOR is crucial for suppressing the irreversibility at its source. Herein, using the discovery of plateau hysteresis in ribbon-ordered Na-deficient transition metal oxides (Na-deficient-TMOs) in Li half cells, we reveal that the alkali-ion coordination environment of O controls the voltage hysteresis by affecting the oxygen orbital energy level maldistribution. The prismatic site is more advantageous to the uniform distribution of oxygen orbitals. This work provides an essential component for understanding voltage hysteresis and emphasizes the importance of alkali-metal-site doping for designing high-voltage oxygen redox materials with low voltage hysteresis.