The improvement of high-energy-density batteries is a major focus in current research owing to consumer demand for sophisticated electronic gadgets and the everincreasing demand for electric vehicles. Conventional Liion batteries cannot satisfy present demand, whereas allsolid-state batteries(ASSB) could be suitable because of favorable factors such as high volumetric and gravimetric energy density, safety, and long life cycle. Fast ion conducting (FIC) solids form an integral part of ASSB and are a leading topic of current research . Significant efforts have been devoted over the last three decades to the advancement of Li + ion conducting materials . Recently, sodium ion conductors have been reported to be promising for energy storage applications because the Na ion has a very similar intercalation chemistry to the Li ion and, in some cases, the Na ionic radius is more suitable for stabilizing fast ion conducting frameworks because of its larger size compared with the Li ionic radius. Thus, the development of sodium ion conducting ASSB working at ambient temperatures is gaining renewed attention.