One-Pot Synthesis of Co3 O4 /Ag Nanoparticles Supported on N-Doped Graphene as Efficient Bifunctional Oxygen Catalysts for Flexible Rechargeable Zinc-Air Batteries.

Abstract

Flexible rechargeable zinc-air batteries are considered as one of the most promising power supplies for the emerging flexible and wearable electronic devices. However, the development of flexible zinc-air batteries is stagnant due to the lack of efficient bifunctional catalysts with high oxygen catalytic activity and flexible solid-state electrolytes with high mechanical stability and ionic conductivity. In this work, Co3 O4 /Ag@NrGO composite was synthesized by a facile one-pot method, and the catalyst shows remarkable oxygen reduction reaction (ORR)/oxygen evolution reaction (OER) bifunctional catalytic activity and good long-term stability. In particular, the OER overpotential of Co3 O4 /Ag@NrGO reaches 437 mV, outperforming that of the commercial IrO2 catalyst. This can be attributed to the combined effects of Co3 O4 , Ag, and N-rGO. Furthermore, PAA (polyacrylic acid) and PVA (polyvinyl alcohol) based gel-electrolytes have been developed as flexible solid-state electrolytes for zinc-air batteries. The results show that PAA-based electrolyte is more favorable to the flexible zinc-air battery with a high power density due to its relatively high ionic conductivity. The maximum power density of flexible zinc-air batteries with Co3 O4 /Ag@NrGO catalyst and PAA-based electrolyte can reach 108 mW cm-2 , which is almost the highest value reached in recent reports. This work will provide valuable guidance for the development of flexible rechargeable zinc-air batteries with high power density and stability.