The technique of scanning electron microscopy has
been used to observe morphological changes occurring
in the redox processes involved in the interconversion
of lead dioxide and lead sulphate. Observations have
been made on lead dioxide films on platinum and pure
lead substrates and on one and two dimensional porous
lead dioxide electrodes supported either by pure lead
or lead-antimony alloys.
The morphology of the surfaces examined was found to
be strongly affected by their history, particularly
their charge/discharge cycles. Lead sulphate formed
by the self corrosion process was much more porous
than that formed by the electrochemical reduction of
lead dioxide. For porous lead dioxide electrodes
cycled to a constant response, three well defined
regions were found to exist within the electrode.
The oxidation of lead sulphate on lead and leadantimony
alloys has shown that a duplex layer of lead
dioxide existed on the lead-antimony alloys only.
The primary layer of lead dioxide found on these
alloys was analogous to the single layer on the pure
lead electrodes. The observations of the morphological
changes occurring in the two dimensional porous elect/
trodes were not consistent with the theory of the
macrohomogeneous model for porous lead dioxide, possible
interpretations of these results are discussed.
A Master's Thesis. Submitted in partial fulfilment of the requirements for the award of Master of Philosophy of Loughborough University.