Polyoxometalate on rice paper derived 3D mesoporous carbon paper: An electrocatalyst as cathode for asymmetric Zn-air battery

Abstract

Asymmetric Zn-air battery is an ideal power source because of its high voltage and powder density. Acidic active bifunctional oxygen reduction reaction and oxygen evolution reaction electrocatalyst determines the performance of asymmetric Zn-air battery greatly. Here, an efficient bifunctional electrocatalyst is synthesized through the loading of coordination compound modified polyoxometalate on rice paper derived nitrogen doped carbon paper. This elctrocatalyst exhibits three-dimensional network with bulky appearance, which can be employed as air cathode in asymmetric Zn-air battery directly. In acidic electrolyte, it oxygen reduction reaction completes through a typical four-electron process. In oxygen evolution reaction, its overpotential is only 359 mV. With this electrocatalyst as air cathode and Zn plate as anode, an asymmetric Zn-air battery is assembled. The open circuit voltage of this battery is 2.09 V. Its peak power density achieves 349 mW cm−2. When discharge at 20 mA cm−2, its specific energy density reaches 1009 Wh·kg−1. Furthermore, this battery keeps stable in long time charge-discharge experiments. This asymmetric Zn-air battery is superior to traditional Zn-air battery in both charge and discharge process. This work describes an efficient acidic active bifunctional electrocatalyst to construct asymmetric Zn-air battery with high voltage and powder density.