Chemical Polishing Behavior of Sodium β"-Alumina Electrolytes

Sodium ion conducting solid electrolytes based on sodium β"-alumina phase, useful in sodium-sulfur batteries, were exposed to phosphoric acid to determine the chemical polishing conditions. Under suitable conditions of acid concentration, exposure time, and exposure temperature, samples of sodium β"-alumina were polished by phosphoric acid. The kinetics of polishing was studied, and a polishing mechanism is proposed. Insignificant effect of chemical polishing on the fracture strength of sodium β"-alumina electrolyte was obtained.