Materials analysis for nickel-cadmium space cells

Three sets of Ni-Cd space cells have been evaluated by destructive physical analysis procedures which involve extensive materials analysis. The author discusses the results of the materials analysis with particular attention to the NASA Goddard procedural process as modified by Crane Division, US Naval Surface Warfare Center, and the discrepancies between theoretical Cd:Ni electron exchange ratios and actual material analysis results on cells at complete discharge. The sets include baseline cells and cells after two shadow periods and five shadow periods of cycling in simulation of a polar low Earth orbit environment. The results of the chemical and physical characterizations are presented in a comparative manner, and the degradative effects on material properties are discussed