Experimental study and performance characterization of a single-cell vanadium redox flow battery

摘要

Vanadium redox flow battery (VRFB) is a promising technology to store large scale renewable energy. The objective of this research is to investigate the impact of various operating parameters of a lab-scale single-cell VRFB test-bed. The single-cell test-bed VRFB was built and tested with variations of multiple parameters including electrolyte concentrations, current densities, electrolyte flowrates, and ratio of electrolyte volume in tank to cell. The measured data from the tests were analyzed in terms of energy storage capacity, and efficiencies of coulombic, voltage, and energy. It was found that both VOSO4 and H2SO4 concentrations in electrolyte have significant roles in reduction of vanadium ions transfer and subsequent improvement in energy storage capacity. Energy storage capacity was enhanced by 9 % over four cycle operations with both the increase of H2SO4 concentration from 2 to 6 M and decrease of VOSO4 concentration from 2 to 1.2 M. The highest energy efficiency was found at 67 % under operating conditions of 1.6 M VOSO4 in 4 M H2SO4 electrolyte, 220 ml/min flowrate, 27 mA/cm2 current density, and 7 ratio of electrolyte volume in tank to cell. It was observed that coulombic efficiency was increased by 15 % by increasing current density from 15 to 40 mA/cm2. Energy storage capacity was reached up to 10 Wh when the ratio of electrolyte volume in tank to cell was 7.