Chemical adsorption: another way to anchor polysulfides

Lithium-sulfur (Li-S) batteries are known for their high energy density but suffer from poor cycling performance due to severe dissolution of the polysulfides (PSs) in liquid electrolyte and their shuttle effect. Effectively anchor the PS should combine the physical and chemical adsorption. However, most of the current studies are focused on confining the PS mobility by physical adsorption alone. Herein, chemical adsorption of the PS is emphasized in a special cell with functionalized graphene adsorbers. Both the experimental and calculated results show that functional groups containing C, N, O and P atoms are beneficial for immobilizing the PSs via chemical bonding, such as C-S, O-S, P-S. Such cells deliver a reversible capacity as high as 1218 mA h g(-1) and cycle stably by solely applying the chemical adsorption, comparable to the current reports mostly based on physical adsorption. Our findings enrich the fundamental understanding of the chemical adsorption of the PS and shed light on the design of sulfur electrodes. (C) 2014 Elsevier Ltd. All rights reserved.