Self-supporting porous CoS2/rGO sulfur host prepared by bottom-up assembly for lithium-sulfur batteries

Cobalt disulfide (CoS2) has been revealed as strong adsorption and activation sites for polar polysulfides, which effectively accelerates the redox reactions of polysulfides in lithium-sulfur (Li-S) batteries. As an ideal sulfur host, a three-dimensional (3D) graphene framework is adopted for high-performance Li-S batteries. Considering the special function of the CoS2 nanoparticles and the advantages of a 3D porous graphene framework, a porous CoS2/reduced graphene oxide (CoS2/rGO) binder-free sulfur host is prepared by a bottom-up assembly and hydrothermal treatment. The porous rGO film is stacked by interconnected graphene sheets, and the CoS2 nanoparticles are dispersed on the graphene sheets uniformly, which effectively obstructs the stacking of graphene sheets. As a binder-free sulfur host, the porous CoS2/rGO sulfur host combines the sufficient electron conductivity of the porous rGO framework and the sulfur immobilization interaction of the CoS2 nanoparticles. This host material demonstrates an initial discharge capacity of 993.5 mAh g(-1) and a capacity of 806.7 mAh g(-1) after 110 cycles at 0.5 C. Both the capacity and cycling stability of the CoS2/rGO cathode were greatly improved over that of rGO. Furthermore, the bottom-up assembly approach provides a novel opportunity for preparing self-supporting graphene-based nanocomposite electrodes. (C) 2018 Elsevier B.V. All rights reserved.