Integrated Polypyrrole@Sulfur@Graphene Aerogel 3D Architecturevia Advanced Vapor Polymerization for High-Performance Lithium−Sulfur Batteries
Although lithium-sulfur batteries have been regarded as the most promising candidates for next-generation energy storage devices with high specific capacity, their rapid capacity decay, mainly caused by volume expansion and dissolution of polysulfides, has limited their practical applications. Aiming at these issues, herein, we have designed an ideal three-dimensional (3D)-structured polypyrrole@sulfur@graphene aerogel (PPy@S@GA) as an efficient sulfur host via advanced pyrrole vapor polymerization. GA with an interconnected 3D porous structure provides an excellent conductive network for electrons and a channel for ion transfer, as well as a physical barrier or absorber for the polysulfides. In addition, physical confinement and chemical adsorption are further strengthened by the PPy coating layer with polar nitrogen. The electrode with the PPy@S@GA 3D structure delivered a superior initial discharge specific capacity of 1135 mA h g-1 and a capacity of 741 mA h g-1 after 500 cycles at a rate of 0.5 C, with capacity fading as low as 0.031% per cycle, superior to both a sulfur electrode and a S@GA electrode. These results demonstrate that GA as a sulfur host further coated with PPy is a promising cathode for pursuing high-performance Li-S batteries.