Migration barrier assisted oxygen redox stability in NMO cathode

Designing a battery that has high energy density and high reversibility remains a challenge in modern research. For example, 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, a recent study showed an exceptional reversibility and low-voltage hysteresis of oxygen-redox active cathode, Na₂Mn₃O₇ (NMO) (Mortemard de Boisse et al., 2018). In this work, we utilize ground state and excited state calculation to determine the redox mechanism of NMO that enabled in the low voltage hysteresis of the cathode. The results provide insight into NMO defect structures that are unfavorable kinetically but can be detrimental to the stability of the NMO cathode material.