Functional CNTs@EMIM + -Br - Electrode Enabling Polysulfides Confining and Deposition Regulating for Solid-State Li-Sulfur Battery.

With an extremely high theoretical energy density, poly(ethylene oxide) (PEO)-based solid-state lithium-sulfur (Li-S) batteries are emerging as one of the most feasible and safest battery storage systems. However, the long-term cycling performance is severely impeded by polysulfides (Li 2 S n , n = 4-8) shuttling and terrible electrode passivation from the electronic insulating Li 2 S. Here, a novel cathode through chemically grafted 1-Ethyl-3-methylimidazolium bromide (EMIM + -Br - ) to carbon nanotube (CNTs) for PEO-based Li-S batteries is reported (CNTs@EMIM-Br/S). Concretely, bi-functional mediator EMIM + -Br - not only inhibits the polysulfides shuttling by strong chemical interactions via EMIM + , but also facilitates the electrochemical kinetics for promoting the formation of 3D particulate Li 2 S through high donor anion (Br - ). Satisfactorily, dual-function CNTs@EMIM-Br/S cathode exhibits high sulfur utilization with the capacity of up to 1298 mAh g -1 , and keeps high capacity retention of 80.2% at 0.2 C after 350 cycles, exceeding that of many reported PEO-based solid-state Li-S batteries. This work will open a new door for rationally designed architecture to enable the practical applications of advanced Li-S batteries.