High capacity alkaline super-iron boride battery

Abstract

A high capacity alkaline redox storage chemistry is explored based on a novel Fe 6+/B 2− chemistry. The alkaline anodes based on transition metal borides can deliver exceptionally high electrochemical capacity. Over 3800 mAh/g discharge capacity is obtained for the commercial available vanadium diboride (VB 2), much higher than the theoretical capacity of commonly used zinc metal (820 mAh/g) alkaline anode. Coupling with the super-iron cathodes, the novel Fe 6+/B 2− battery chemistry generates a matched electrochemical potential to the pervasive, conventional MnO 2–Zn battery, but sustains a much higher electrochemical capacity. Stability enhancement of super-iron boride battery is also studied. A zirconia coating effectively prevents both the decomposition of boride anodes and the passivation of Fe(VI) cathodes, and sustains facile both anodic and cathodic charge transfer. Reversibility of boride anodes is demonstrated with TiB 2 and VB 2. It is shown that these two boride anodes exhibit the reversibility in a certain extent.