Evaluation of Sodium Sulfur Cell Characteristics Using an In Situ X‐Ray Computed Tomogram System

An in situ X-ray computed tomogram system to observe a sodium sulfur cell was constructed with a 0.14 g/cm 3 density resolution and 0.17 mm spatial resolution. Density distributions in the radial cross sections of the sodium sulfur cell were obtained by the system during charge and discharge operations at 350°C. The typical behavior of sodium supplied to the surface of the solid-electrolyte tube was observed. The experimental density changes of the sulfur electrode agreed with the theoretical values during charge and discharge operations except in one part of the cell.