PNNL

Abstract

A sandwich structured graphene sheet-sulfur (GSS) nanocomposite was synthesized as the cathode material for lithium-sulfur batteries. The structure has a layer of graphene stacks and a layer of sulfur nanoparticles integrated into a three-dimensional architecture. This GSS nanoscale layered composite, making use of the efficient physical and electrical contact between sulfur and the large surface area, highly conductive graphene, provides a high loading of active materials of ~70 wt%, a high tape density of ~0.92 g·cm-3, and a high power with a reversible capacity of ~505 mAh·g-1 (~464 mAh·cm-3) at a current density of 1,680 mA·g-1 (1C). When coated with a thin layer of cation exchange Nafion film, the migration of dissolved polysulfide anions from the GSS nanocomposite was effectively alleviated, leading to a good cycling stability of 75% capacity retention over 100 cycles. This sandwich-structured composite conceptually provides a new strategy for designing electrodes in energy storage applications.