The importance of Confined Sulfur Nano-Domains and Adjoining Electron Conductive Pathways in Sub-Reaction Regimes of Li-S Batteries

Abstract

Polysulfide dissolution into the electrolyte and poor electric conductivity of elemental sulfur are well-known origins for capacity fading in lithium–sulfur batteries. Various smart electrode designs have lately been introduced to avoid these fading mechanisms, most of which demonstrate significantly improved cycle life. Nevertheless, an in-depth understanding on the effect of sulfur microstructure and nanoscale electron transport near sulfur is currently lacking. In this study, the authors report an organized nanocomposite comprising linear sulfur chains and oleylamine-functionalized reduced graphene oxide (O-rGO) to achieve robust cycling performance (81.7% retention after 500 cycles) as well as to investigate the reaction mechanism in different regimes, i.e., S8 dissolution, polysulfide conversion, and Li2S formation. In the nanocomposite, linear sulfur chains terminate with 1,3-diisopropylbenzene are covalently linked to O-rGO. The comparison with control samples that do not contain either the capping of sulfur chains or O-rGO reveals the synergistic interplay between both treatments, simultaneously unveiling the distinct roles of confined sulfur nanodomains and their adjoining electron pathways in different reaction regimes. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim