Unlock flow-type reversible aqueous Zn-CO 2 batteries.

Metal-CO 2 batteries, which use CO 2 as the active species at cathodes, are particularly promising, but device design for mass-producible CO 2 reduction and energetic power supply lag behind, limiting their potential benefits. In this study, an aqueous reversible flow-type Zn-CO 2 battery using a Pd/SnO 2 @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 CO 2 and produce valuable chemicals, addressing current energy and environment issues simultaneously.