Study on electrochemical properties of Pb(BF4)2 electrolyte for improvement of cycle lifetime and efficiency in soluble lead flow batteries

Abstract

The electrochemical characteristics of a soluble lead flow battery are key factors for the improvement of its cyclic lifetime and efficiency. In this work, we suggested aqueous solution of Pb(BF4)2 and HBF4 as the electrolytes of soluble lead flow battery and observed the kinetic behavior of the electrode by cyclic voltammetry of the cyclic lifetime, quantum efficiency and voltage efficiency of the SLFB with respect to concentration of the electrolyte. Both the density and viscosity of the electrolyte increase with an increasing [Pb(BF4)2]. The conductivity exhibits a peak at 1.5 mol/L Pb(BF4)2 when [HBF4] is below 1.0 mol/L. According to the cyclic voltammetry, the electrode process is fast with a low overvoltage and no additional reactions for the aqueous solution with 1.5 mol/L Pb(BF4)2 and 0.25 mol/L HBF4. Overall, for the aqueous solution of 1.5 mol/L Pb(BF4)2 and 0.25 mol/L HBF4, the battery showed a best performance with the cyclic lifetime being 48 times, the average quantum efficiency 88%, the voltage efficiency 70% and the battery efficiency 62%. These results are promising for fresh parameters of the electrolyte that could play a major role for the improvement of SLFBs.

Keywords

• Soluble lead flow batteries
• Pb(BF4)2
• HBF4
• Lead dioxide
• Battery efficiency
• Cycle lifetime