Electrochemical performance of α-Fe₂O₃ particles as anode material for aqueous rechargeable batteries

This paper presents a nontoxic, environmentally and friendly anode material for aqueous rechargeable battery. Two kinds of anode materials, α-Fe ₂O₃ nano-needle and nano-platelet particles for aqueous rechargeable battery, are synthesized via a facile hydrothermal method. The crystal structure of Fe₂O₃ particles is characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Moreover, the obtained α-Fe₂O ₃ particles are used as the anode materials of Ni- MH batteries, and their electrochemical performance is investigated. Compared with nano-platelet particles, nano-needle α-Fe₂O₃ particles show a higher specific capacity of 468 mAh g_-1 and a shorter activation time. This can be ascribed to the small particle size and large specific surface of nano-needle α-Fe₂O₃ particles. Both of these two samples possess stable and high capacity of about 140̃150 mAh g _-1. Furthermore, the reaction corresponding to the stable capacity, 3Fe(OH)2 + 2OH- → Fe3O4 + 4H2O + 2e-, is found in the discharge process. It is believed that the reduction of discharge capacity is mainly due to the fact that the reaction of Fe(OH)₂ to FeOOH is repressed.