Dye-functionalized carbonaceous interlayer as an efficient lithium polysulfide mediator for high performance lithium-sulfur batteries

Abstract

Lithium - sulfur (Li-S) batteries with their high theoretical energy density and abundant resources have been considered as a promising candidate for next-generation energy storage systems. Nonetheless, undesirable diffusion of lithium polysulfides (LiPSs) toward the lithium metal anode in electrolytes during discharge/charge cycles of Li-S batteries, which is known as shuttle behavior of LiPSs, degrades the long-term stability of Li-S batteries and limits their practical applications. Herein, we present dye-functionalized carbonaceous interlayer, in which organic dye containing nitrogen and sulfur functional groups are incorporated into the carbon matrix of a graphitic layer via hydrothermal process. The introduction of such functional interlayer in Li-S batteries reveals that the carbon matrix with various heteroatom moieties can create physically/chemically favorable active sites for trapping LiPSs and enhance LiPSs conversion toward insoluble products of Li2S/Li2S2, resulting in excellent rate capability and long-term stability with high coulombic efficiency. This study emphasizes the potential of organic dyes functionalization and demonstrates enhanced LiPSs conversion and long-term stability of Li-S batteries.