Formation of Large Polysulfide Complexes during the Lithium-Sulfur Battery Discharge

Abstract

Sulfur cathodes have much larger capacities than do the components in commercial lithium-ion batteries, but their long-term performance suffers due to diffusion of soluble polysulfides into the electrolyte. This first-principles molecular dynamics study reveals the formation at high Li/S ratios of large, $i\phantom{\rule{0}{0ex}}n\phantom{\rule{0}{0ex}}s\phantom{\rule{0}{0ex}}o\phantom{\rule{0}{0ex}}l\phantom{\rule{0}{0ex}}u\phantom{\rule{0}{0ex}}b\phantom{\rule{0}{0ex}}l\phantom{\rule{0}{0ex}}e$ Li-S clusters that ultimately fuse into a network, and also predicts stabilization of soluble polysulfides by functionalized graphene-based materials incorporated into the cathode. These results offer a road map for progress in battery technology.