Lithium-ion batteries (LIBs) which have high energy density and light weight are widely used in portable devices such as cell phones, laptops, etc. However, the increasing price of lithium resources limits the applications of LIBs for large-scale energy storage systems. Sodium-ion batteries (NIBs) have been proposed as a promising candidate for large-scale energy storage systems because of the abundance and low cost of sodium resources. Several NIB cathode materials have been developed in recent years, and P2-type transition metal oxides (NaTMO2, TM = Ti, V, Cr, Mn, Fe, Co, Ni) have attracted much attention because of their special layered structures which provide large space to storage Na ions thus lead to high specific capacity.
In this study, Na0.5MnxFeyNi(1-x-y)O2 was utilized as cathode material for NIBs because of the abundance and nontoxicity of those transition metals. Furthermore, effects of metal doping on Na0.5MnxFeyNi(1-x-y)O2 were also investigated. Na0.5MnxFeyNi(1-x-y)O2 and its metal doing were synthesized through a facile co-precipitation method followed by heat treatment. The metal-doped Na0.5MnxFeyNi(1-x-y)O2 exhibited high specific capacity as well as good cycling stability, demonstrating this NIB cathode material is suitable for large-scale energy storage applications.