Improving the cyclability of lithium–sulfur batteries by coating PPy onto the graphene aerogel-supported sulfur

Abstract

The graphene aerogel/sulfur/polypyrrole composite with a three-dimensional (3D) porous structure was prepared by the impregnation of sulfur into graphene aerogel and then the electro-polymerization of polypyrrole on the surface of sulfur. For this composite, the 3D porous graphene aerogel provides an interconnected conductive framework to improve the electron conductivity and the utilization of sulfur. The encapsulation of polypyrrole on the sulfur can restrict the polysulfide diffusion and enhance the cycling stability of the lithium–sulfur battery. The micro-structure characterization confirms the homogeneous dispersion of sulfur and polypyrrole on the graphene aerogel backbone. The graphene aerogel/sulfur/polypyrrole composite cathode with a sulfur content of 73 wt% presents an initial discharge capacity of 1288 mA h g⁻¹ and maintains 1017 mA h g⁻¹ after 100 charge–discharge cycles at 0.5C, which is much higher than that of the composite lacking polypyrrole.