Fig. 4: The structural and chemical evolution mechanisms upon air-exposure.
From: The stability of P2-layered sodium transition metal oxides in ambient atmospheres
a The XRD evolutions of Na0.67Ni0.33Mn0.67O2 powder exposed at RH 93% + CO2 atmosphere for different times (MgO was used as internal indicator). b 23Na{1H} REDOR-dephased 23Na MAS NMR spectra (MAS rate: 25 kHz) and c The XRD patterns of exposed NaxNi0.33Mn0.67O2 electrodes with various Na+ content x. d The FTIR spectra of Na0.67MnO2 samples with various hydration degrees. e The structure model of single layer Na+ loss structure for calculating hydration energies. f The calculated hydration energies for NaxMnO2 at various sodium contents x.
