Reversible Aqueous Zinc–CO2 Batteries Based on CO2–HCOOH Interconversion

Abstract

AbstractAs a promising technique for CO2 fixation/utilization and energy conversion/storage, the metal–CO2 battery has been studied to improve its interconversion between CO2 and carbonates/oxalates. Herein, we propose and realize a reversible aqueous Zn–CO2 battery based on the reversible conversion between CO2 and liquid HCOOH on a bifunctional Pd cathode. The 3D porous Pd interconnected nanosheet with enriched edge and pore structure, has a highly electrochemical active surface to facilitate simultaneous selective CO2 reduction and HCOOH oxidation at low overpotentials. The resulting battery has a 1 V charge voltage, a cycling durability over 100 cycles, and a high energy efficiency of 81.2 %. The battery mechanism is proposed as Zn+CO2+2 H++2 OH−↔ ZnO+HCOOH+H2O, through which the reversible conversion between CO2 and liquid HCOOH was realized.