Quinone-Based Flow Battery with Increased Open Circuit Voltage

Quinone-based flow batteries exhibit rapid redox kinetics, contain no electrocatalyst and use very inexpensive redox active materials [1]. Consequently, they appear to be very attractive candidates for inexpensive, large-scale electrical energy storage. We compare the performance of several substituted quinone/hydroquinone redox couples in an aqueous flow battery. We show that various substitutional groups can alter the electrochemical properties of the quinone, which in turn affects the performance of the flow battery. One substituted quinone at the negative electrode, when combined with Br₂/HBr at the positive electrode, exhibits an open circuit voltage exceeding 1.0 V and a peak galvanic power density exceeding 0.24 W/cm²when fully charged.

Fig. 1.  Polarization plot (a) and galvanic power densities (b) of a substituted quinone-bromine flow battery at various states of charge (SOC).  The electrodes are Toray carbon paper with no electrocatalyst. The membrane is Nafion 212. The negative side is 0.5 M substituted quinone in 1 M sulfuric acid. The positive electrode is 1.5 M hydrobromic acid, 0.25 M bromine.