Long‐life room‐temperature sodium‐sulfur batteries by virtue of transition metal nanocluster‐sulfur interactions

Room‐temperature sodium‐sulfur (RT‐Na/S) batteries hold significant promise for large‐scale application because of low cost of both sodium and sulfur. However, the dissolution of polysulfides into the electrolyte limits practical application. Here, we report the design and testing of a new class of sulfur hosts as transition metal (Fe, Cu, and Ni) nanoclusters (~ 1.2 nm) wreathed on hollow carbon nanospheres (S@M‐HC) for RT‐Na/S batteries. A chemical couple between the metal nanoclusters and sulfur is hypothesized to assist in immobilization of sulfur and to enhance conductivity and activity. S@Fe‐HC exhibited an unprecedented reversible capacity of 394 mAh g‐1 despite 1000 cycles at 100 mA g‐1, together with the a rate capability of 220 mAh g‐1 at a high current density of 5 A g‐1. Importantly, density functional theory calculations underscore that these metal nanoclusters serve as electrocatalysts to rapidly reduce Na2S4 into short‐chain sulfides and thereby obviate the 'shuttle effect'. We conclude these novel S host cathodes will provide new opportunities to construct electrode materials for various practical battery technologies.

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