High-voltage pH differential vanadium-hydrogen flow battery

We report a rechargeable pH differential vanadium-hydrogen (V-H-2) flow battery with a practical open circuit voltage of 1.93 V and a discharge voltage of 1.73 V. This value is among the highest reported values for rechargeable flow batteries with aqueous electrolytes to date. This proposed V-H-2 system demonstrates relatively high efficiencies in voltage (89%), Coulomb (85%) and energy (75%). Moreover, V-H-2 system shows a high experimental specific energy of 135.6 Wh kg(-1) which is about 2.6 times higher than that of the state-of-the-art all vanadium redox flow battery. This work offers new opportunities to develop high-specific-energy energy storage technologies. (C) 2018 Elsevier Ltd. All rights reserved.