Effect of temperature on physicochemical properties of PbO2 deposits in the soluble lead flow battery

Abstract

The weatherability of soluble lead flow battery is critical to its large-scale and safety application. In this work, physicochemical properties of PbO2 deposits are investigated at different temperatures, 50, 20, 0 and -20 °C. The deposit formed at low temperature has the higher discharge capacity than that formed at high temperature when they are discharged at the same temperature of 20 °C. With the temperature decreased from 50 to -20 °C, the relative content ratio of α-PbO2: β-PbO2 changes from 0: 100 to 33: 67. The non-stoichiometric ratio of Olattice: Pb in PbO2 deposits increases from 1.31 ± 0.15 to 1.67 ± 0.18. And particle sizes of PbO2 deposits become fine, from 4.29 ± 1.71 to 2.08 ± 0.93 µm, and their distributions become narrow. This indicates that physicochemical properties of PbO2 deposits can be improved by increasing activation overpotential through decreasing temperature. However, the cycling performance of batteries becomes worse at low temperature, even though the high activity PbO2 deposits is obtained after charge. It can be well explained from the limiting current-density and exchange current density of positive electrode significantly decreases with decreasing temperature.