Interface polymerization synthesis of conductive polymer/graphite oxide@sulfur composites for high-rate lithium-sulfur batteries

Abstract

The novel ternary composites, conductive polymers (CPs)/graphene oxide (GO)@sulfur composites were successfully synthesized via a facile one-pot route and used as cathode materials for Li-S batteries The poly(3,4-ethylenedioxythiophene) (PEDOT)/GO and polyaniline (PANI)/GO composites were prepared by interface polymerization of monomers on the surface of GO sheets. Then sulfur was in-situ deposited on the CPs/GO composites in same solution. The component and structure of the composites were characterized by XPS, TGA, FTIR, SEM, TEM and electrochemical measurements. In this structure, the CPs nanostructures are believed to serve as a conductive matrix and an adsorbing agent, while the highly conductive GO will physically and chemically confine the sulfur and polysulfide within cathode. The PEDOT/GO@S composites with the sulfur content of 66.2wt% exhibit a reversible discharge capacity of 800.2mAhg−1 after 200 cycles at 0.5C, which is much higher than that of PANI/GO@S composites (599.1mAhg−1) and PANI@S (407.2mAhg−1). Even at a high rate of 4C, the PEDOT/GO@S composites still retain a high specific capacity of 632.4mAhg−1.