Influence of Impurity Ions in the Electrolyte on Vanadium Battery Performance

Study on the influence of impurity ions in electrolyte is critical for optimizing and improving the performance of vanadium battery. Considering electrolyte materials and operation of vanadium battery,two typical ions,SiO₃^2- and Fe²⁺,were selected as the research object. The influences of SiO₃^2- and Fe²⁺ on electrochemical activity of graphite electrode and coulombic efficiency,voltage efficiency,energy efficiency and capacity attenuation of battery were investigated by cyclic voltammetry and charge-discharge test,aiming to provide theory basis for the impurity ions control in electrolyte. The results suggest that Fe²⁺ does not affect the reaction activities of the electrodes and battery efficiency,and the capacity of battery is improved by adding Fe²⁺. Nevertheless,SiO₃^2- reduces the reaction activity,voltage and energy efficiency of the electrodes and accelerates the rate of capacity attenuation of battery. Thus,SiO₃^2- should be avoided during the manufacture and use of vanadium electrolyte.