Microelectrode studies of battery reactions

Creasey, Mark Richard (1991) Microelectrode studies of battery reactions. University of Southampton, Doctoral Thesis.

Abstract

Phase transformations occurring in the lead-acid battery are investigated using microelectrodcs and x-ray diffraction.

In-situ and ex-situ x-ray diffraction is used to investigate the electrochemistry controlling the morphological composition and structure of electrode-posited films of PbOj, and to characterise positive plates of lead-acid batteries. The amorphous nature of battery plates is shown to cause complications in calculating the proportions of a-and /S-PbOj in the plates.

A review identifies the assumptions and inadequacies of current electro-crystallization theories, principally in their implicit models of nucleation. Computer simulations of a stochastic model of nucleation show how the model can advance our understanding of the clustering processes occuring prior to nucleation of stable crystals, and the limits of this approach.

Studies of the oxidation of lead microelectrodcs in sulphuric acid provide evidence that the conversion of lead to lead sulphate occurs solely via a dissolution-precipitation mechanism. Lignosulphonate battery 'expander' is shown to increase the density of nucleation on the microelectrode surface.

Distributions of arrival times for the nucleation of single crystals of Pb on carbon-fibre microelectrodcs are interpreted using a stochastic model for nucleation to show that the critical cluster size for lead nuclei is of the order of a few atoms. The observed overpotential dependence of the clustering processes indicates that the rate of nucleation of new crystals is determined by surface diffusion of adatoms. Stochastic analysis provides an insight into how battery expander influences lead nucleation, indicating that it reduces the rate of dissolution of subcritical clusters.

This record has no associated files available for download.

Contributors

Download statistics