Experimental Study on Effects of Operational Parameters on a Single-Cell Test-Bed Vanadium Redox Flow Battery

This paper describes the experimental characterization of a laboratory scale single-cell vanadium redox flow battery (VRFB) with variations of operational parameters. The single cell was experimentally investigated with respect to energy storage capacity, charge-discharge time, voltage, coulombic and energy efficiencies under various operating parameters such as current densities, electrolyte flow rates, and the ratio of electrolyte volume in electrolyte storage tank and cell. It was found that the voltage efficiency was increased by 11% entailing energy efficiency improvement from 60 to 66% as the electrolyte flowrate was increased from 40 to 220 ml/min. The highest columbic efficiency was achieved at 96% for the current density of 40 mA/cm2 which was 14% higher than that of the current density of 15 mA/cm2. Energy storage capacity was linearly increased with higher ratio of tank to cell volume due to the larger number of vanadium ions present. The improvement in energy storage capacities was observed to be 60, and 41% as the ratio was raised by 67, and 40%, respectively.