Sulfur-Polypyrrole/Graphene Multi-Composites as Cathode for Lithium-Sulfur Battery

Abstract

The polypyrrole (PPy) is deposited by in situ chemical oxidation polymerization on the surface of the commercial multilayer graphene sheets to prepare PPy/graphene composite. Subsequently, sulfur is loaded to form sulfur-polypyrrole/graphene multi-composites with different sulfur contents. It is shown that the amorphous polypyrrole with a chain-like morphology exists on the surface of the multilayer graphene sheets, and the crystalline sulfur can be loaded into the pores of polypyrrole or dispersed on the surface of the multilayer graphene sheets. It is demonstrated that the sulfur-polypyrrole/graphene multi-composite with 50 wt% sulfur presents the optimized electrochemical performance, including the utilization of active sulfur, discharge capacity and cycle stability, as compared to the sulfur/graphene composite with the same sulfur loading. Obviously, the multiplex matrix of the amorphous polypyrrole and multilayer graphene sheets is essential for increasing the sulfur loading based on the dual fixing mode, and improving the electrochemical performance of the sulfur cathode.