Enhanced sodium ion batteries performance by the phase transition from hierarchical Fe2O3 to Fe3O4 hollow nanostructures

Hierarchical Fe3O4 hollow nanostructures are synthesized from the phase transition of Fe2O3 hollow nanostructures, which are prepared through a dissolution-recrystallization process. The hierarchical Fe3O4 hollow nanostructures, applied as an anode material for Na-ion batteries, display good rate capability and cycling stability. The reversible capacity of 150 mAh/g at 100 mA/g after 50 cycles can be maintained for Fe3O4 anode. The superior Na-ion storage properties of hierarchical Fe3O4 could be largely ascribed to the stable electrode structure during Na-ion insertion and extraction process. On the contrary, Fe2O3 anode exhibits a high initial discharge capacity (686 mAh/g), but it suffers from poor cycling stability due to the remarkable pulverization of the electrode.