Methanesulfonic acid solution as supporting electrolyte for zinc-vanadium redox battery

Abstract

The present work was performed in order to evaluate methanesulfonic acid (MSA) as electrolyte medium for V(IV)/V(V) redox couple as positive species applied in redox flow battery (RFB). V-MSA solutions containing more than 3.0molL−1 vanadium ions were obtained. Conductivity and viscosity of 3.0molL−1 V(IV)/V(V) electrolyte were determined to be 0.10cms−1 and 12.37mPas respectively. Cyclic voltammetry was conducted to investigate the electrochemical behavior of V(IV)/V(V) redox couple. The diffusion coefficients of V(IV) on Pt electrode in 1.0, 2.0 and 3.0molL−1 V(IV)/V(V) electrolytes determined were 3.606×10−6, 1.813×10−6 and 0.5244×10−6cm2s−1, respectively. A ZnV battery was assembled with V(IV)/V(V)-MSA positive species and Zn/Zn(II)-MSA negative species. The cell voltage in charged state was 1.9–2.0V and discharge voltage reached up to 1.7V. The average coulombic efficiency and energy efficiency of the assembled cell were 95.85% and 63.90% respectively and it showed a good cyclic charge–discharge performance, which indicates that MSA has a promise application prospect in vanadium redox battery.