Single-atom Catalytic Materials for Lean-electrolyte Ultrastable Lithium-Sulfur Batteries.

Abstract

Lithium-sulfur batteries with high energy capacity are promising candidates for advanced energy storage. However, their applications are impeded by shuttling of soluble polysulfides and sluggish conversion kinetics with inferior rate performance and short cycling life. Here, single-atom materials are designed to accelerate polysulfide conversion for Li-S batteries. Nitrogen sites in the structure not only anchor polysulfides to alleviate the shuttle effect but also enable high loading of single-atom irons. Density functional theory calculations indicate that single-atom sites reduce the energy barrier of electrochemical reactions and thus improve the rate and cycling performances of batteries. The coin battery shows impressive energy storage properties, including a high reversible capacity of 1379 mAh g^-1 at 0.1 C and a high rate capacity of 704 mAh g^-1 at 5 C. The ratio of electrolyte dosage/energy density is as low as 5.5 g Ah^1-. It exhibits excellent cycling performance with a capacity retention of 90% even after 200 cycles at 0.2 C.