A Supramolecular Complex of C60 -S with High-Density Active Sites as a Cathode for Lithium-Sulfur Batteries

Abstract

The well-known "shuttle effect" of the intermediate lithium polysulfides (LiPSs) and low sulfur utilization hinder the practical application of lithium-sulfur (Li-S) batteries. Herein, we describe a novel C₆₀ -S supramolecular complex with high-density active sites for LiPS adsorption that was formed by a simple one-step process as a cathode material for Li-S batteries. Benefiting from the cocrystal structure, 100 % of the C₆₀ molecules in the complex can offer active sites to adsorb LiPSs and catalyze their conversion. Furthermore, the lithiated C₆₀ cores promote internal ion transport inside the composite cathode. At a low electrolyte/sulfur ratio of 5 μL mg^-1 , the C₆₀ -S cathode with a sulfur loading of 4 mg cm^-2 exhibited a high capacity of 809 mAh g^-1 (3.2 mAh cm^-2 ). The development of the C₆₀ -S supramolecular complex will inspire the invention of a new family of S/fullerenes as cathodes for high-performance Li-S batteries and extend the application of fullerenes.

Keywords: fullerenes; high-density active sites; lithium-sulfur batteries; shuttle effect; supramolecular complexes.