Ca‐substituted Na3SbS4 glass–ceramic electrolytes: Achieving high conductivity and excellent interfacial stability

Abstract Super conductor Na 3 SbS 4 has received substantial attention in electrolyte research because of its high ionic conductivity and low grain boundary resistance. A breakthrough in electrochemical stability with good ionic conductivity has yet to be captured. Calcium (Ca) appears as an ideal substitute for sodium (Na) due to its abundance in geological resources, nontoxic properties, and equivalent ionic radius. The proposed Na 3‐2 x Ca x SbS 4 glass–ceramic electrolytes were subsequently manufactured using ball milling and heat treatment. The results acquired the maximum ionic conductivity of 1.59 mS cm −1 at room temperature, which reached the commercial use level when compared with the current popular lithium‐ion battery. Moreover, calcium ions partially replaced sodium sites while creating massive Na vacancies to maintain charge neutrality, resulting in fast ion transport. Furthermore, a more stable ionic bond Ca–S was formed at the interface, which inhibited additional reactions at the electrolyte–metal interface and demonstrated exceptional cyclic stability, making it a viable electrolyte for solid‐state sodium‐ion batteries.