Parameters influencing the ratio between electrochemically formed α- and β-PbO2

The interparticle contact is an important aspect for the capacity of all lead dioxide electrodes. It can be discussed with respect to the ratio of the two lead dioxide phases, α- and β-PbO2. Of the two phases the α-PbO2 has a more compact structure compared to the more porous β-PbO2, resulting in a better contact between the particles. It has previously been shown that different perchlorate salts have an influence on the discharge properties, the self discharge and the active surface area of formed PbO2. The results were attributed to crystal structure defects caused by the cations and it was suggested that different cations may influence the ratio between α- and β-PbO2 resulting in different discharge properties. In the present study, structural changes of electrochemically formed lead dioxide were studied as a function of formation time, current, porosity, interparticle contact, and electrolyte cation by X-ray powder diffraction and scanning electron microscopy (SEM). Three different electrode thicknesses 100, 200 and 400 μm were investigated at two current densities and with four perchlorate salts, KClO4, NaClO4, LiClO4 and HClO4. The initial results indicate that the ratio of α/(α+β) increased when a larger cation was used in the order H+