Recent progress in the development of beta-alumina for the sodium-sulphur battery

The development of beta-alumina as the electrolyte and separator for the sodium-sulphur battery is described. The requirements of cell performance and durability determine the mechanical and electrical properties of the electrolyte. Changes in the cell configuration also have an effect in so far as extending the area of the electrodes and electrolyte and reducing their thickness will reduce the overall impedance of a cell. The manner in which this interacts with the manufacturing route is outlined. The methods by which high ionic conductivity are achieved whilst maintaining adequate mechanical strength are described and the extent to which these are mutually exclusive is discussed. Some of the factors responsible for the failure of beta-alumina in sodium-sulphur cells are considered in relation to recent experimental studies.