Nitrogen-doped graphene aerogel as both a sulfur host and an effective interlayer for high-performance lithium-sulfur batteries.

ABSTRACT

Lithium-sulfur batteries have attracted great concern because of the high theoretical capacity of sulfur (1675 mA h g-1). However, the poor electrical conductivity and volumetric expansion of sulfur along with the dissolution of lithium polysulfides largely limit their practical application. In this study, nitrogen-doped graphene aerogel (NGA) with high nitrogen content and porosity is used as a host for the impregnation of sulfur. The effects of sulfur impregnation on the specific surface area, pore volume, and microstructure of NGA supported sulfur composite (S@NGA) are well investigated. Furthermore, NGA is also processed into a NGA film, which is sandwiched between a separator and S@NGA cathode. The lithium-sulfur battery with such a configuration delivers a high reversible capacity of 1514 mA h g-1 at 0.1 C, excellent rate performance (822 mA h g-1 at 2.0 C), and good cycling stability (946 mA h g-1 at 0.5 C even after 100 cycles). The enhanced electrochemical performance can be ascribed to the introduction of the NGA interlayer, the unique interconnected porous structure, and strong interaction between the three-dimensional nitrogen-doped graphene network and the homogeneously dispersed sulfur and/or lithium polysulfides.