Investigation on the Air Stability of P2-Layered Transition Metal Oxides by Nb Doping in Sodium Ion Batteries

Sodium-ion batteries are regarded as a substitution for lithium-ion its abundant resources, wide distribution, low cost, etc. The P2-layered sodium transition metal oxides (P2-NaxTMO2) have attracted extensive attention due to their high rate and cycling properties. However, P2-NaxTMO2 often undergoes structural transformations when exposed in ambient air, which restricts practical applications. Herein we studied the effect of Nb doping on air stability P2-NaxTMO2. We demonstrated that Nb-induced surface preconstructed layer inhibited dissolution P2 material electrochemical reaction formed stable thin (cathode–electrolyte interphase) CEI film, prevented water molecules from entering lattice. Na0.67Mn0.67Ni0.33Nb0.03O2 could exhibit superior performance (a reversible capacity 72.5 mAh g−1 at 20 C) outstanding (84.43% retention after 1000 cycles 5 half cell moisture atmosphere (RH93%) days.