Dual-Confined Sulfur Cathodes Encapsulated in MnO2 Nanotubes and Wrapped with PEDOT for High-Performance Lithium-Sulfur Batteries

alpha-MnO2 nanotubes were developed as host material to fill with sulfur in their tubular hollow space, and then the sulfur were further encapsulated by a thin layer of poly (3,4-ethylenedioxythiophene) (PEDOT) exterior coating via an in situ polymerization process. Such a dual-confined sulfur cathode, denoted as S@alpha-MnO2-PEDOT, showed high performance in lithium-sulfur batteries. It could reach a capacity of 774.4 mAh.g(-1) at a current density of 1 675 mA.g(-1) (1C) after 200 cycles and 854.1 mAh.g(-1) at a current density of 3 350 mA.g(-1) (2C), manifesting excellent cycling stability and rate capability. The outstanding performances are attributed to the new architecture. In the novel architecture, alpha-MnO2 nanotubes not only provide the physical confinement for sulfur, but also enhance the chemical interaction between the sulfur host material and polysulfides. Simultaneously, PEDOT was introduced to enhance conductivity of sulfur-containing nanocomposites and further reduce the loss of sulfur due to volumetric change and the excessive dissolution of lithium polysulfides.