Electrochemical properties of electrolyte for lead fluoroborate redox flow battery prepared with recovered lead

The electrochemical properties of electrolyte for soluble lead flow battery(SLFB) are a key factor for the improvement of its performance. Pb(BF4)2 in which Pb2+ ions are highly soluble is cheaper and more stable than conventional Pb(CH3SO3)2. This paper presents the electrochemical properties of HBF4 and Pb(BF4)2 prepared with recovered lead for the electrolytes of SLFB. The density difference of reagent grade and recovered lead electrolytes is less than 0.05 g/cm3 and their viscosities increase up to 132 %, 120 %, respectively when concentration of Pb(BF4)2 changes from zero to 2.0 mol·dm−3. The conductivity of 1.5 mol·dm−3 electrolyte prepared with recovered lead has a peak when concentration of HBF4 is less than 1.0 mol·dm−3. The results of cyclic voltammetry, linear sweep voltammetry and constant current charge/discharge test showed that impurities of recovered lead exert insignificant influences on the Pb2+/Pb and Pb2+/PbO2 reactions. These results are promising to apply recovered lead to SLFB.