An Acid-Base Electrochemical Flow Battery as energy storage system

• Published in: International journal of hydrogen energy 2016-10, Vol.41 (40), p.17801-17806
• Main Authors: Sáez, Alfonso, Montiel, Vicente, Aldaz, Antonio
• Format: Article
• Language: English
• Subjects: Acid; Base; Energy storage system; Hydrogen; Redox flow battery
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2016.08.141

In this paper, we present a new Acid-Base Electrochemical Flow Battery (ABEFB). This system is composed of acidic and alkaline solutions, both with a high supporting electrolyte concentration. These solutions are separated by a proton exchange membrane, using hydrogen as both a reactant and a product. Under this configuration, neutralization energy is used as electromotive force. Thus, in the charging process, hydrogen is oxidized to form hydronium ions (hydrogen oxidation reaction –HOR-) (positive electrode) that acidifies positive electrolyte or posilyte, while hydrogen is formed from water (hydrogen evolution reaction –HER-) (negative electrode) that basifies negative electrolyte or negalyte. On the other hand, during the discharging process, both electrolytes are neutralized through hydrogen oxidation and hydrogen evolution reactions. A platinised titanium electrode is chosen for HER and a platinum-catalysed gas diffusion electrode is used for HOR. This proof of concept has been verified for several charge capacities obtaining a maximum power density of 20 mW cm−2 at 49 mA cm−2. In this sense, faradaic efficiency close to 95% and energy efficiency of 55% are also obtained. Finally, the reuse of produced hydrogen is an interesting aspect to be considered. •An Acid-Base Electrochemical Flow Battery (ABEFB) is presented.•While charging, solutions are acidified and basified, respectively.•While discharging, solutions are neutralized individually.•Hydrogen oxidation reaction and hydrogen evolution reaction are main reactions.•Hydrogen evolution and self-supply could be carried out.