Uniform Fe2O3 Nanospheres Anchored on Multilayer Graphene as Anode Materials for High-Rate Ni-Fe Batteries.

Ni-Fe battery is one of prospective aqueous alkaline batteries due to its high safety, eco-friendliness and cost-effectiveness. However, the electrochemical performance of Fe-based anodes is limited due to the particle aggregation and low electric conductivity. In this work, iron powder is used as a precursor in a chemical bath deposition method. By optimizing the concentration of HNO3, a balanced dissolution-crystallization process is achieved to obtain uniform Fe2O3 nanospheres in size between 60 and 90 nm, which are separately anchored on ultrasonically prepared multilayer graphene (MLG). This composite delivers specific discharge capacities of 191.1 and 160.8 mAh g-1 at the current densities of 2 and 10 A g-1, respectively. A Ni-Fe battery with the as-prepared Fe2O3/MLG as anode and Ni(OH)2/MLG as cathode exhibits an energy density of 69.5 Wh kg-1 at a high power density of 3931.6 W kg-1.