Progress in the development of solid-state electrolytes for reversible room-temperature sodium–sulfur batteries

Abstract

Proliferation in population with booming demand for viable energy storage solutions led to the exploration of storage technology beyond lithium-ion batteries. Sodium–sulfur batteries are potential candidates for post-lithium-ion energy storage courtesy of their high theoretical specific capacity and energy with lower material cost and abundance. However, their general consideration is significantly slowed down by the safety concerns, sodium polysulfide dissolution, and subsequent shuttling in liquid electrolytes, which negatively lower the electrochemical performance and shorten the cycle life. Room-temperature solid-state sodium–sulfur batteries with high electrochemical performances and enhanced safety are excellent analogs based on leakage-free modified electrolytes. However, developments in solid-state electrolytes are in their infancy, with issues such as lower ionic conduction, interfacial instability, and lower capacity retention. This review summarizes developments in room-temperature solid-state sodium–sulfur batteries, focusing on various methods to improve ionic conduction while ensuring interfacial stability and enhancing the overall electrochemical properties. From a combined physico-electro-chemical approach, bifurcation based on the electrolyte material, classified as an inorganic and organic solid polymer electrolyte, has been discussed with its merits and demerits. Finally, several perspectives and insightful conclusions are discussed, citing the crucial challenges that need optimization and rectification.