A comparative study of layered transition metal oxide cathodes for application in sodium-ion battery

Herein we report a study on P-type layered sodium transition metal-based oxides with general formula NaxMO2 (M=Ni, Fe, Mn). We synthesize the materials via co-precipitation followed by annealing in air and water rinsing process and examine the electrodes as cathodes for sodium-ion battery using a propylene carbonate (PC) based electrolyte. Following, we fully investigate the effect of Ni to Fe ratio, annealing temperature and sodium content on the electrochemical performances of the electrodes. The impact of these parameters on the structural and electrochemical properties of the materials is revealed by X-ray diffraction, scanning electron microscopy and cyclic voltammetry, respectively. The suitability of this class of P-type materials for sodium battery application is finally demonstrated by cycling tests revealing an excellent electrochemical performance in terms of delivered capacity, i.e. of about 200 mAh g-1, and charge-discharge efficiency, approaching 100 %