Nitrogen, sulfur-codoped graphene sponge as electroactive carbon interlayer for high-energy and -power lithium-sulfur batteries

摘要

Sulfur is an attractive cathode material in energy storage devices since its high theoretical capacity of 1672 mAh C-1. However, practical application of lithium sulfur (Li-S) batteries can be achieved only when the major barriers, including the insulating nature of element sulfur and shuttling effect of polysulfides (Li2Sx, x = 3-8), are tackled. Here, nitrogen, sulfur-codoped (N,S-codoped) sponge-like graphene, which presents a high reversible capacity, is used as electroactive interlayer for Li-S batteries to address these issues. An impressive high capacity of 2193.2 mAh g(-1) can be obtained for the sulfur cathodes with such an interlayer at the rate of 0.2C, and it can be stably maintained at 829.4 mAh g(-1) at the rate of 6C, for which the contribution from the electroactive interlayer is ca. 30.0%. High energy density of 418.5 Wh Kg(-1) still can be released at the power density of 4.55 kW kg(-1) (6C) based on the total mass of the sulfur cathode and interlayer for the assembled Li-S batteries. (C) 2015 Elsevier B.V. All rights reserved.