Trends in the Development of Room-Temperature Sodium–Sulfur Batteries

This review examines research reported in the past decade in the field of the fabrication of batteries based on the sodium–sulfur system, capable of operating at an ambient temperature (room-temperature sodium–sulfur (Na–S) batteries). Such batteries differ from currently widespread lithium-ion or lithium–sulfur analogs in that their starting materials are cheaper and more readily available. One of the key problems to be resolved on the way to room-temperature Na–S batteries with high energy density and long-term cycling stability is transport of cell reaction products (sodium polysulfides) to the opposite electrode, which leads to an appreciable battery self-discharge and loss of the active material as a result of redox reactions that are not accompanied by energy generation. This review is aimed at examining approaches to improving the electrochemical performance of the room-temperature Na–S batteries. Particular attention is paid to potential applications of cation-exchange materials capable of suppressing polysulfide anion transport, with a high sodium cation transport rate retained.