Unlock flow-type reversible aqueous Zn–CO2 batteries

Metal-CO₂ batteries, which use CO₂ as the active species at cathodes, are particularly promising, but device design for mass-producible CO₂ reduction and energetic power supply lag behind, limiting their potential benefits. In this study, an aqueous reversible flow-type Zn-CO₂ battery using a Pd/SnO₂@C cathode catalyst has been assembled and demonstrates an ultra-high discharge voltage of 1.38 V, a peak power density of 4.29 mW cm^-2, high-energy efficiency of 95.64% and remarkable theoretical energy density (827.3 W h kg^-1). In the meantime, this optimized system achieves a high formate faradaic efficiency of 95.86% during the discharge process at a high rate of 4.0 mA cm^-2. This energy- and chemical-conversion technology could store and provide electricity, eliminate CO₂ and produce valuable chemicals, addressing current energy and environment issues simultaneously.