Development of Air Cathode Materials for Metal- Air Batteries

Abstract

Fluctuation in oil price and the effect of global warming forced us to look for the replacement of this fossil fuel by advanced high energy density metal air batteries. To bring this advanced technology to commercialize market we need to have noble metals (such as Pt/C) and metal oxides (such as RuO2 and MnO2) as catalysts in cathode to facile the oxygen reduction reaction while discharging process and oxygen evolution reaction when recharging the battery. However, the replacement of these noble metal-based catalysts is due to often suffer from multiple disadvantages, including high cost, low selectivity, poor stability and detrimental environmental effects. We developed one dimensional LaCo1-xNixO3-δ perovskites by simple electrospinning approach. We show that the progressive replacement of Co by Ni in the LaCo0.97O3- δ perovskite structure greatly altered the OER electrocatalytic activity and the La(Co0.71Ni0.25)0.96O3-δ composition exhibited the lowest overpotential of 324 at 10 mAcm-2 in 0.1M KOH. Subsequently as prepared La(Co0.71Ni0.25)0.96O3-δ nanostructured was used as cathode catalyst for aqueous zinc-air battery, which delivers high capacity of 705 mAh.g-1zinc in primary zinc-air battery. The rechargeable battery discharges with low overpotential of 0.792 V and 0.696 V at low capacity mode (400 mAh.g-1 catalyst) and high capacity mode (2500 mAh.g-1catalyst), respectively, this value is much lower than LaCo0.97O3-δ nanotube catalyst and precious Pt/C catalyst. In the second part of thesis, we synthesized a thin film carbon coated SiO2 nanosphere by hydrothermal method and we utilized this material as cathode catalyst for lithium-air battery, it delivers a capacity of 18588 mAh.g-1 of catalyst material at high current density of 150 mAh.g-1, which is nearly twice the capacity of nitrogen doped carbon material at same current density, and for rechargeable battery it last for ten cycles at a cutoff capacity of 1000 mAh.g-1. Later to elucidate the working mechanism behind this metalloid oxide catalyst, we also reported the post mortem analysis of cathode material of lithium-oxygen battery. ⓒ 2016 DGIST