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

• Electroactive N,S-codoped graphene as interlayer for Li–S batteries is reported.
• N,S-codoped graphene presents a high discharge capacity and good conductivity.
• High rate capability and discharge capacity is obtained using such interlayer.
• High energy density of 1106.5 Wh Kg−1 is obtained based on cathode and interlayer.
• Energy density of 418.5 Wh Kg−1 can be released at power density of 4.55 kW kg−1.

Sulfur is an attractive cathode material in energy storage devices since its high theoretical capacity of 1672 mAh g−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.

N,S-codoped sponge-like graphene, which presents a high reversible capacity to offer extra capacity, and contains rich doping heteroatoms to restrict the dissolution of polysulfide, is used as electroactive interlayer for Li–S batteries. By this method, the sulfur cathode shows an ultrahigh discharge capacity and superior high rate performance.Figure optionsDownload as PowerPoint slide