A Rechargeable Hydrogen Battery Based on Ru Catalysis

Abstract Apart from energy generation, the storage and liberation of energy are among the major problems in establishing a sustainable energy supply chain. Herein we report the development of a rechargeable H 2 battery which is based on the principle of the Ru‐catalyzed hydrogenation of CO 2 to formic acid (charging process) and the Ru‐catalyzed decomposition of formic acid to CO 2 and H 2 (discharging process). Both processes are driven by the same catalyst at elevated temperature either under pressure (charging process) or pressure‐free conditions (discharging process). Up to five charging–discharging cycles were performed without decrease of storage capacity. The resulting CO 2 /H 2 mixture is free of CO and can be employed directly in fuel‐cell technology.