All-lead redox flow battery in a fluoroboric acid electrolyte

Abstract

An all-lead redox flow battery in a fluoroboric acid electrolyte is proposed. The same electrolyte was used as both the negative and positive electrodes, and it consists of a high concentration solution of Pb(BF4)2 in aqueous fluoroboric acid, i.e., 0.1, 0.5, 1.0 and 1.5 mol·L-1 Pb(BF4)2 in 1.0 mol·L-1 HBF4. The properties of the graphite and glassy carbon electrodes for both the positive and negative electrodes as current collectors were compared using cyclic voltammetry. We found that the graphite substrate was better than glassy carbon for both the negative electrode and the positive electrode. The all-lead redox flow battery was constructed using graphite substrates as both the positive and negative electrodes with a single electrolyte flow passing though the two electrodes. The performance of the batteries was evaluated using the constant current charge/discharge technique. Typically, an average coulombic efficiency of above 87% and an average energy efficiency of above 68% were obtained. An average energy efficiency of above 74% was achieved with electrolyte containing 1.0 or 1.5 mol·L-1 Pb(BF4)2 + 1.0 mol·L-1 HBF4 at current densities of 10 and 20 mA·cm-2. © Editorial office of Acta Physico-Chimica Sinica.