Iron-Tungsten Redox Flow Battery

A redox flow battery based on phosphotungstic acid as anolyte and ferrous sulphate as catholyte has been investigated. The configuration allows for higher capacity due to the presence of multiple oxidation states of the phosphotungstate ion. The reactions at both electrodes have been found to be kinetically facile with high Coulombic efficiency. Along with basic electrochemical investigation of the two redox couples by means of cyclic voltammetry and polarization experiments using rotating disc electrodes, simulation of the cyclic voltammograms was also performed to determine the kinetic parameters and the diffusion coefficients specially for the phosphotungstate anions. In addition, a flow cell of 6.25 cm(2) active area was constructed and assembled in house using a normal single cell fuel cell setup and then charge/discharge and i-V polarization studies were performed. The maximum discharge current of 160 mA cm(-2) and maximum power density of 49.43 mW cm(-2) were obtained from the i-V polarization curve. Meanwhile, an average Coulombic efficiency of 90.94% and maximum specific capacity of 620 mAh l(-1) at 50 mA cm(-2) was realized from the charge/discharge experiments.