Advancing solid-state sodium batteries: Status quo of sulfide-based solid electrolytes

Solid-state sodium batteries are among the most promising candidates for replacing conventional lithium-ion batteries for next-generation electrochemical energy storage systems. Their advantages include abundant Na resources, lower cost, enhanced safety, and high energy density. Central to the development of these batteries is the use of all-solid-state sodium electrolytes, with sulfide-based solid electrolytes emerging as particularly viable due to their high ionic conductivity (on par with liquid electrolytes), favorable interfacial contact with electrodes, and mild preparation conditions. Despite these benefits, several crucial challenges limit the development of sulfide-based solid electrolytes, including a narrow electrochemical stability window, unstable interface between sulfide-based solid electrolytes and electrodes, and the growth of detrimental sodium dendrites. This review examines the fundamental ion transport mechanism in sulfide-based solid electrolytes, discusses the primary challenges and strategic solutions, and separately addresses the critical interfacial issues at the cathode and anode. It also highlights the importance of scaling up these techniques for industrial applications. Finally, this review offers key recommendations for advancing the industrialization and enhancing the energy density of sulfide-based solid-state sodium batteries. Hopefully, solid-state sodium batteries based on sulfide-based solid electrolytes will achieve significant breakthroughs in energy density and industrial scalability in the very near future.