Polyaniline-Coated Mesoporous Carbon/Sulfur Composites for Advanced Lithium Sulfur Batteries

Lithium sulfur (Li-S) batteries have been considered as a promising candidate for high energy density applications with a high theoretical capacity of 1675 mAh g(-1) and a high energy density of 2600 Wh kg(-1). In this work, a polyaniline (PANi)-coated mesoporous carbon composite is synthesized by direct polymerization of aniline monomer in mesoporous Ketjenblack (KB) carbon and is used as cathode material for LiS batteries. Different mass percentages of PANi can be infiltrated into the pores of KB carbon by simply varying the amount of monomer. Sulfur is encapsulated into the composite by the melt diffusion method, and the electrochemical performance of lithium sulfur batteries is investigated. The results indicate that the mass percentage of PANi plays a crucial role in the cycle stability of lithium sulfur batteries. The infiltrated PANi is capable of enhancing the intimate contact of sulfur with carbon and trapping polysulfides, which improves the utilization of active material. However, excess PANi diminishes the pore volume of mesoporous KB carbon, which limits sulfur loading and impairs the capability of cells. The cell with the composite containing 30% of PANi shows an improved cyclability of 675 mAh g(-1) after 200 cycles at 0.1 C-rate, demonstrating promising applications in Li-S batteries with high energy density.