Electrochemical Behavior Promotion of Polysulfides by Cobalt Selenide/Carbon Cloth Interlayer in Lithium−Sulfur Batteries

Graphical Read my LiPSs : A CoSe 2 /CC composite interlayer structure limiting liquid lithium polysulfides (LiPSs) is prepared to address the problem of polysulfides susceptibility to dissolution in lithium−sulfur batteries, which accelerates the reduction of soluble LiPSs and the reuse of insoluble product Li 2 S. The electrochemical results confirm that CoSe 2 /CC achieves high capacity and good cycling stability as an interlayer, and maintains high Coulombic efficiency under high loading and low current conditions, indicating that the shuttle of LiPSs is effectively suppressed. Lithium−sulfur batteries have been regarded as the next generation of competitive batteries because of their high theoretical capacity and energy density. However, the commercial development of lithium−sulfur batteries is restricted by the shuttle action of polysulfides and volumetric expansion of sulfur. Herein, we developed cobalt selenide/carbon cloth composites (CoSe 2 /CC) as the interlayer. CoSe 2 can not only limit the shuttling of polysulfides by Co−S bonds and accelerate the catalytic conversion kinetics of sulfur chemistry, but also increases the electrical conductivity of materials, leading to an excellent cycle stability. As a result, the cell with CoSe 2 /CC interlayer has a high initial capacity of 1420 mAh g −1 at 0.1 C and keeps high-capacity retention of 596 mAh g −1 after 500 cycles at 1 C rate (70 %). Subsequent electrochemical tests show that CoSe 2 /CC enhance the electrochemical behavior of the polysulfides. Therefore, the hierarchical CoSe 2 /CC composites have promising application potential in lithium−sulfur batteries.