During the course of this work two fundamental aspects of the electrochemistry of the
lead acid battery system have been investigated. The first area of study concerns the
respective roles of alpha and beta lead dioxide in the positive plate, and more
specifically the interconversion behaviour of the two polymorphs.
The second research area concerns the occurence of a passivating layer of lead
monoxide between substrate lead and the active material of the electrode. A subject of
extreme importance to the lead acid battery manufacturer, since passivating layers of this
type are acknowledged as being one of the major failure modes.
This work has differed from most before it, in that use has been made of
electrodeposits of the two modifications to study both the interconversion products, and
the conditions necessary for lead monoxide formation.
A survey of some of the recommended methods of preparation for the two forms of
lead dioxide has been carried out and compared to the data given in the Powder
X-ray diffraction has been the major investigative tool utilised, and electrodes have been
subjected to analysis in both the powder and unground state, after both galvanostatic and
Cyclic voltarnmetry was used to study the potentiodynarnic conversion products of
deposits swept between the hydrogen and oxygen gas evolution regions in sulphuric
The galvanostatic cycling showed that a conversion of alpha lead dioxide to the beta
does occur, although evidence for conversion of the beta form to the alpha was not
The potentiodynamic study revealed that in order for lead monoxide to be formed under
deposits of beta lead dioxide, the presence of substrate lead is required beneath a lead
sulphate film or membrane. Under these conditions it was discovered that the lead
monoxide itself is a precursor to alpha lead dioxide formation.
A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough University.