Physicochemical and Electrochemical Characterization of Vanadium Electrolyte Prepared with Different Grades of V2O5 Raw Materials

Abstract

The physicochemical and electrochemical performance of electrolytes prepared with different grades of V2O5 raw materials were investigated systematically for a vanadium redox flow battery. Physicochemical tests showed that the conductivity of electrolytes prepared with lower grades of V2O5 raw materials obviously decreased, while the viscosity increased. The results of electrochemical experiments showed that the electrochemical activity and reversibility of electrolytes decreased, and the solution resistance increased obviously, as the grade of V2O5 raw materials gradually decreased. In addition, the battery efficiency and charge–discharge capacity were negatively affected by impurities in the lower grade V2O5 raw materials, due to an increase of polarization on the charge–discharge voltage. Moreover, the performance of electrolytes was related to the total concentration of impurities in the electrolyte, and Na, K impurity ions were the main factors that adversely affected the electrochemical activity and reversibility, mass transfer, and capacity of the electrolytes. Based on the economic analysis, the impurities in V2O5 raw materials would not only reduce the performance of electrolytes, but also affect the production costs of electrolytes and the economic profits. Through this fundamental research, people can better understand the influence of V2O5 raw materials on electrolyte properties, and direct more attention to research how to effectively use lower grade V2O5 raw materials to reduce the costs of electrolyte preparation.