Solid‐State Electrolyte Materials for Sodium Batteries: Towards Practical Applications

Abstract The huge demand for delocalized energy storage due to the application of fluctuating energy sources leads to a need for low‐cost devices available on a large scale and with high energy density. Solid‐state sodium batteries (SSNBs) show great potential in this field and have recently attracted extensive interest. Several review‐type publications have already discussed fundamental materials properties and more academic aspects related to ionic transport and charge transfer. In contrast, the current Review uses state‐of‐the‐art 18650 Li‐ion batteries as a benchmark and evaluates solid‐state electrolytes (SSEs) and corresponding SSNBs in terms of their practical applicability and development status. This Review summarizes recent progress based on key properties of various SSEs, such as ionic conductivities, chemical stabilities, mechanical properties, interface compatibilities with sodium metal, and compares the published SSNBs in detail with respect to galvanostatic cycling and full cell performance. It provides insights and perspectives with respect to SSEs for SSNBs and indicates the direction of future developments for the practical application of SSNBs.