Performance of the all-vanadium redox flow battery stack

The all-vanadium redox flow battery (VRFB) stack of a kW class, which was composed of 31 cells with an electrode surface area of 2714 cm2 and a commercial anion exchange membrane, was tested using the electrolyte of 1.2 M VOSO4 in 2 M H2SO4. The charge–discharge cycle performance of VRFB stack was measured at the current density of 60 and 90 mA cm−2. Average energy efficiencies during charge–discharge cycle in the VRFB stack were about 76% and 70% for the current density of 60 and 90 mA cm−2, respectively. It was confirmed from the tested data that the homemade VRFB stack is suitable for the electric storage with high efficiency. The input power (IP) and output power (OP) in the VRFB stack at 90 mA cm−2 were 11.4 kW and 8.9 kW, respectively.