Progress in the Development of Sodium‐Ion Solid Electrolytes

Abstract The development of safe, reliable, yet economical energy storage has been reemphasized with recent incidents involving the explosion and subsequent recall of lithium‐ion batteries. The organic liquid electrolyte used in the conventional lithium‐ion battery can potentially act as a fuel for combustion in a thermal‐runaway reaction, and hence an alternative with a significantly reduced flammability must be sought. All‐solid‐state batteries have the potential to meet safety and reliability requirements with the possibility of increasing the volumetric energy density of the system, making these a promising candidate for the development of the next generation of energy storage. Moreover, the sodium‐ion battery exhibits a better cost‐efficiency without significantly compromising the energy density, making the combination of the sodium chemistry with the solid electrolyte an attractive choice for safe and economical energy storage. Here, a general background on the recent development of ceramic and glass‐ceramic sodium‐ion‐conducting electrolytes is provided with regard to oxide‐, sulfide‐, and hydride‐based electrolytes. The ionic conductivity, chemical stability, and mechanical properties of the sodium‐based solid electrolyte are discussed, which is followed by a perspective on future developments in the field.