Investigation of Proton Diffusion Coefficient for PbO2 Prepared from Intermediate Oxides

Abstract

Lead dioxide was extracted from used batteries, and used to synthesize the following intermediate oxides by heating at different temperatures: Pb12O19, Pb12O17, and Pb3O4. Each of the prepared intermediate oxide was subject to sulfuric acid with 1.28 g cm–3. X-ray diffraction (XRD) results showed that the sample prepared from Pb12O19 only had a pattern similar to that of the starting PbO2 with α-PbO2 and β-PbO2 phases. The measurements of H+ proton diffusion coefficient (DH+) of the different samples showed that the sample prepared from Pb12O19 had better electrochemical performances than the starting PbO2. This kinetics reflects the proton insertion mechanism in PbO2, i.e. the sample prepared from Pb12O19 has a large amount of structural water in OH– hydroxyl form. This amount contributes more in the PbO2 reduction mechanism. In addition, the DH+ value of the sample prepared from Pb12O19 is significantly higher than that of starting PbO2, which confirms this hypothesis. X-ray diffraction analysis, thermogravimetric and differential thermogravimetry analysis, and cyclic voltammetry reduction at different scanning rates were used to investigate the samples. This work contributes to environment preservation by recycling of used lead dioxide and reduction of the hazard of its disposal on water.