Porous polymer thin film encapsulated sulfur nanoparticles on graphene via partial evaporation for high-performance lithium–sulfur batteries

Lithium–sulfur batteries, owing to their excellent advantages (including low cost and high theoretical energy density), might be the next-generation energy storage devices. However, the low S contents in their electrodes and the shuttling effect of soluble polysulfides can significantly deteriorate their capacities and cycle lives. Herein, we demonstrate a uniquely structured composite electrode, named porous polymerized vinyl acetate (p-PVAc) thin films, to break through the “trade-off” between the energy density and rate capability. S nanoparticles were encapsulated by porous p-PVAc layers and then anchored on graphene (p-PVAc/S/G), facilitating ion exchange and electron transfer during electrochemical operations. Consequently, p-PVAc/S/G delivered a high specific capacity of 719 mAh g⁻¹ at 0.1 A g⁻¹ and exceeded even 350 mAh g⁻¹ at a high current density of 5 A g⁻¹, whereas the average Coulombic efficiency was preserved to be higher than 98.50% when repeated for more than 300 cycles at 1 A g⁻¹.