Review—Manganese-Based P2-Type Transition Metal Oxides as Sodium-Ion Battery Cathode Materials

Abstract

Sodium transition metal oxides (NaMO2) with a P2 structure exhibit good Na+ ion conductivity and are promising sodium-ion battery cathode materials. Manganese-based compounds have a high working potential vs. Na+/Na, and high capacity. Yet, the layered nature of these materials means that they are prone to structural rearrangements at high voltage/low Na contents, the phase transformations and Na+ ion/vacancy ordering transitions resulting in capacity fade and poor reversibility. This review discusses the latest advances in the field and focuses mainly on recent work on NayMn1-xMxO2 (x, y