Vacancy assisted oxygen redox stability in Na-cathode*

Battery cathode material has been an increasingly popular research area due to the increasing demand for electric cars and energy storage solutions. However, designing a battery that has high energy density and high reversibility remains a challenge in modern research. Oxygen-redox active cathodes provide a promise for higher capacity than conventional cathodes, such as LiCoO₂, but are prone to voltage hysteresis and capacity fading during charging cycles. However, recent studies showed an exceptional reversibility and low-voltage hysteresis of oxygen-redox active cathode, Na₂Mn₃O₇ (NMO). In this work, we utilize ground state and excited state calculation to determine the redox mechanism of different sodium-based cathode material and investigate how defect structures can impact the stability of different cathode materials.