Efficient CO2 utilization and sustainable energy conversion via Zn–CO2 batteries using gaseous CO2

Abstract

Rechargeable aqueous Zn–CO2 battery is a promising technology that combines energy storage and CO2 utilization to meet the needs of sustainable and eco–friendly energy. However, the practical application of this technology is hindered by factors such as the low current density, low Faradaic efficiency of value–added products, high overpotential, and limited cycles. Cathode catalysts, which are crucial components, significantly influence the performance of the system. There have been several updated publications on cathode materials for aqueous Zn–CO2 batteries, but there are few reports of high–performance Zn–CO2 batteries. Herein, a new system for achieving high performance by injecting gas–phase CO2 was reported. Unlike conventional Zn–CO2 batteries, the problem of low CO2 solubility was overcome by injecting gaseous CO2. The designed Zn–gaseous CO2 battery, powered by Ag or Au catalysts, achieved that Faradaic efficiencies of CO were 92.72 % and 89.56 % at 4 mA/cm2, respectively. The maximum power density of 5.52 mW/cm2 and 7.89 mW/cm2 for Ag and Au catalysts, respectively, were obtained, which were much larger than the power density of conventional aqueous Zn–CO2 batteries. In addition, using X–ray diffraction, ex–situ monitoring of the reaction characterizations on Ag and Au cathodes was carried out and the durability of 600 min was achieved, when using Au cathode. These results offer a practical way to design a Zn–CO2 battery for high-performance energy storage and CO2 utilization.

Keywords

• Zn–CO2 battery
• Electrochemical CO2 reduction
• Gaseous CO2
• Zn recovery