Concepedia

Abstract

This paper briefly describes sodium sulfur (NAS) battery development with emphasis on the program to establish the technology for the use of a β‐alumina solid electrolyte. Since the mid‐1980s, NGK INSULATORS, LTD. (NGK) and the Tokyo Electric Power Company (TEPCO) have jointly conducted the NAS battery development program in Japan and, in April 2003, NGK launched production on a commercial scale. A critical aspect of NAS battery development has been achieving low resistance to the flow of sodium ions through the β‐alumina solid electrolyte while ensuring material properties consistent with high mechanical strength, as well as with the dimensional stability required for automated manufacturing. The resistance to sodium ion flow within β‐alumina depends on three factors: grain resistivity, grain boundary resistivity, and crystal orientation. NGK's approach to addressing these factors is explained in this paper.