Charge-Discharge Performance of a Novel Undivided Redox Flow Battery for Renewable Energy Storage

The redox flow battery is ideal for utility-scale renewable energy storage applications. In this work, a novel undivided battery employing porous flow through electrodes is investigated. Because of low charge-discharge efficiencies reported in previous work employing high superficial electrolyte velocities and current densities, three electrolyte systems are investigated here at two concentrations (0.02 and 0.1 M) employing low-current densities and superficial velocities: [Ru(acac)3] in acetonitrile, [Fe(bpy)3(ClO4)2] in acetonitrile, and VOSO4 in aqueous sulphuric acid (all-vanadium system). The highest energy efficiencies are obtained with the all-vanadium system: 13.4% for 0.02 M electrolyte and 12.0% for 0.1 M electrolyte.