A high performance aqueous iron-hydrogen gas battery

Abstract Rechargeable hydrogen gas batteries are attracting great interest for emerging large-scale energy storage owing to their fast charge/discharge rates and excellent stability. Despite recent progress in the development of different hydrogen gas batteries, it is highly desirable to explore new cathodes for flourishing the hydrogen gas battery chemistries. Different from the previous hydrogen gas battery systems with solid or semi-solid cathode reactions, in this study, we propose and demonstrate an iron-hydrogen gas battery in a liquid cathode with low-cost [Fe(CN)6]3–/[Fe(CN)6]4– redox couple by pairing with the hydrogen gas anode. The designed iron-hydrogen gas battery exhibits a high energy efficiency of 93% with a discharge plateau of ∼1.29 V at a current of 10 mA, an energy efficiency of 73% even at a high current of 60 mA and an ultra-stable cycling life of over 20000 cycles. The present work highlights significance of the deployment of liquid redox molecules as active species in hydrogen gas batteries, which provides an effective strategy to broaden the hydrogen gas battery systems for large-scale energy storage applications.