In situ evaluation of container corrosion in sodium — sulphur batteries

Recent improvements in container materials for Na/S cells (central sodium type) have led to greatly enhanced cell life and performance. Although problems with rapidly decreasing capacity are no longer observed, cells appear to exhibit a slowly increasing resistance with time. This paper describes anin situ technique for assessing the electrical stability of various container materials and determining the extent that corrosion processes influence cell resistance changes. Potentials within the sulphur electrodes of operating cells were measured over prolonged cycling times. Results indicate that chromized steel possesses excellent electrical stability compared to 347 stainless steel and that container corrosion accounts for only a fraction of the increase in total cell resistance.