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.