Identification and characterisation of high energy density P2-type Na2/3[Ni1/3-y/2Mn2/3-y/2Fey]O2 compounds for Na-ion batteries

The composition space between MnO2, NaFeO2, and Na[Ni1/2Mn1/2]O-2 has been explored with the goal of identifying Earth-abundant singlephase P2 cathode materials. This has led to the identification of two compounds, P2-Na-2/3[Ni1/3-y/2Mn2/3-y/2Fey]O-2 (y = 1/6, 1/3) which exhibit state of the art specific energies. These materials were further evaluated through galvanostatic cycling and X-ray absorption spectroscopy.