In Situ Synthesis Method of Approaching High Surface Capacity Sulfur and the Role of Cobalt Sulfide as Lithium-Sulfur Battery Materials.

Lithium-sulfur batteries (Li-S) are potentially applicable in electrification and the replacement of fossil fuels due to the high energy density and the economy of sulfur. However, effectively an insulator, sulfur is known to suffer from inert electrochemical and poor conductivity. By synthetically incorporating conductive, low-dimensional carbonaceous composites acting as both containment hosts and catalysts to active materials, this work entails an effective and straightforward materials engineering approach in fundamentally remodeling active materials utilization and activation. This synthetic-based approach highlights direct processing capabilities than traditional thermal infusion processes without compromising performance and addresses the low activation, poor conductivity as well as alleviating side reactions due to polysulfide species. Motivated by recent efforts in excellent catalytic properties of cobalt sulfide (CoS)-based materials, in this work, high-performance CoS-based carbonaceous composites are designed and employed, alleviating side reactions. These sulfide-based catalysts are further elucidated in their role in facilitating charge/discharge of active materials, and assessed on practical polysulfide and side reaction alleviation with respect to various discharge/charge states. Proof-of-concept devices demonstrate the following performance highlights: 1) high-performance stability, 2) strong polysulfide adsorption capability and kinetic characteristics, 3) large and workable areal capacity, and active materials loading.