Anode Corrosion of Zn-Air Fuel Cell: Mechanism and Protection

Abstract

Zn-air fuel cells are potential for grid-scale storage and portable power sources, which combine high energy density and low cost. However, Zn anodes undergo the corrosion in both the operation and downtime. The corrosion of the Zn electrode causes the low utilization of active materials, the release of hydrogen and heat. The temperature of the Zn electrode even rises above 100 °C in downtime. Here we show that replacing the electrolyte with tiny amounts of glycerol can avoid the thermal runaway of the Zn electrode in downtime. We demonstrate the mechanism of Zn electrode corrosion in the aqueous electrolytes under all operating conditions. Under the open-circuit conditions, the electrode potential causes corrosion. At operation condition, the combination of electrode potential and abscission of Zn particles leads to the corrosion, and the dynamic change of solution/electrode interface brings inductance characteristics. These conclusions and strategies can be applied to not only Zn-air fuel cells but also other metal-based electrodes in aqueous electrolytes.