Water electrolysis is a clean means of directly converting renewable energy into hydrogen. Current electrolysers, mostly based on alkaline and proton-exchange membrane (PEM) electrolysis, present a number of issues regarding the stability of the electrodes over long-term and discontinuous use. More specifically, the production of gas bubbles at their surface is leading to inhomogeneous current distribution and faster degradation. Redox flow batteries (RFBs) store chemical energy in their two circulating liquid electrolytes. The electrolytes composition is therefore of importance, as it is directly related to the overall battery performances, such as storage capacity, output current density and battery voltage, and energy efficiency. Mostly, electrochemical species and electrodes showing a good reversibility are used in such batteries, in order to allow high energy efficiency. Here, a vanadium- cerium redox flow battery (V-Ce RFB) has been developed, and completed with a secondary circuit where the vanadium (II) can be chemically oxidized to produce hydrogen and where the cerium (IV) can be chemically reduced to produce oxygen [1].
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