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 H2 battery which is based on the principle of the Ru-catalyzed hydrogenation of CO2 to formic acid (charging process) and the Ru-catalyzed decomposition of formic acid to CO2 and H2 (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 CO2/H2 mixture is free of CO and can be employed directly in fuel-cell technology. Simple but efficient: A readily accessible Ru catalyst is the basis for a reversible H 2/CO2-driven battery. At elevated temperatures both the reduction of CO2 to formic acid and the decomposition of formic acid were realized with 0.075 mol % of the Ru complex. Several charging and discharging cycles were performed with comparable storage-release efficiency. Furthermore, the partial removal of defined gas amounts is possible under pressure. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.