Pseudo‐Zero‐Gap Flow‐Type Aqueous Zn‐CO ₂ Batteries

ABSTRACT Aqueous Zn‐CO ₂ batteries (AZCBs) generate electricity and convert CO ₂ into valuable products simultaneously, while their development is limited due to poor mass transport, low reactivity, etc. Therefore, we develop AZCBs featuring flowing CO ₂ gases and electrolytes, gas‐diffusion cathodes, and especially a pseudo‐zero interelectrode distance. By employing carbon‐coated bismuth oxides (Bi ₂ O ₃ /C) as the cathode in a pseudo‐zero‐gap AZCB, a record‐high peak power density of 67.0 mW cm ⁻² @current density of 117.5 mA cm ⁻² is achieved, together with excellent cycling performance over 600 cycles. Specifically, the near‐zero distance greatly promotes hydroxide ion transport and CO ₂ diffusion by establishing an enhanced concentration gradient at the reaction interface of CO ₂ electroreduction. Theoretical simulations further indicate preferred formate production is due to the lower energy barrier compared to the CO pathway, because of the favorable ^* O@Bi adsorption via the ^* OCHO intermediate. Significantly, the developed AZCBs operate efficiently and stably in a simulated Martian atmosphere, which is promising for future Human exploration of Mars, providing a potential solution for simultaneous energy generation and feedstock production in the challenging environment.