Lithium-sulphur batteries with a high theoretical energy density are regarded as promising energy storage devices for electric vehicles and large-scale electricity storage. However, the low active material utilization, low sulphur loading and poor cycling stability restrict their practical applications. Herein, we present an effective strategy to obtain Li/polysulphide batteries with high-energy density and long-cyclic life using three-dimensional nitrogen/sulphur codoped graphene sponge electrodes. The nitrogen/sulphur codoped graphene sponge electrode provides enough space for a high sulphur loading, facilitates fast charge transfer and better immobilization of polysulphide ions. The hetero-doped nitrogen/sulphur sites are demonstrated to show strong binding energy and be capable of anchoring polysulphides based on first-principles calculations. As a result, a high specific capacity of 1,200 mAh g⁻¹ at 0.2C rate, a high-rate capacity of 430 mAh g⁻¹ at 2C rate and excellent cycling stability for 500 cycles with ~0.078% capacity decay per cycle are achieved.

Nature Communications 6, Article number: 7760 doi:10.1038/ncomms8760
Received 07 March 2015 Accepted 08 June 2015 Published 17 July 2015

http://www.nature.com/ncomms/2015/150717/ncomms8760/full/ncomms8760.html