Tandem Conversion of Polysulfides via Coupling Ni Single–Atoms and Clusters for Na–S Batteries

Abstract Lithium ion batteries have been trialed for grid−oriented energy storage, yet their large−scale implementation is theoretically limited by the global lithium resource reserve. Relying on abundant sodium and sulfur resources as well as cost−effectiveness, the sodium–sulfur battery is gaining recognition as a promising technology for next−generation grid−oriented energy storage. Nevertheless, their development has been restrained by the low conductivity and huge volume expansion of sulfur, the shuttle effect of polysulfides, and the dendrite growth of sodium. Herein, a host material, bifunctionally designed for both cathodes and anodes, is presented by coupling nickel single atoms and clusters on a nitrogen−doped porous carbon monolith. It accelerates polysulfides conversion kinetics and improves uniform sodium deposition, conferring excellent cycle duration and rate capability. It also allows fast electron and ion transports while alleviating the volume expansion. Consequently, the assembled sodium–sulfur battery demonstrates impressive cycle and rate performances, offering an attractive perspective for advancing durable sodium–sulfur batteries.