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

Muqing Ding,Yimin Zhang,Liming Chen,Hong Liu,Dong Pan,Tao Liu

doi:10.3390/en14185958

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.

Highlights

Renewable energy has been rapidly developed to ease the exhaustion of fossil fuel reserves and the pressure of environmental protection [1,2]
The results indicate that densities, and require greater volumes of electrolytes in the same VRFB system
The results show that the various grades of V2 O5 raw materials affected the performance of the VRFB, and greatly affected the electrolyte costs and the economic profits of the VRFB

Summary

Introduction

Renewable energy has been rapidly developed to ease the exhaustion of fossil fuel reserves and the pressure of environmental protection [1,2]. The intermittent and unstable nature of this energy, such as solar and wind power, makes these valuable electrical energies difficult to apply [3,4]. In view of this problem, the application of large-scale energy storage systems combined with the clean energy can greatly improve the stability and utilization rate of these energy resources. The electrolyte circulates to the surface of the electrodes in the cell stack, where the vanadium ion redox reactions take place. Based on cost analysis of the VRFB system, the cell stack and the electrolyte account for most of the cost.

Methods

Discussion

Conclusion