Carbon nanotubes integrated with multiphasic molybdenum diselenide nanosheets as hybrid membrane accomplish highly efficient electrocatalysts for lithium-sulfur batteries

Abstract

Lithium sulfur (Li-S) batteries are considered a promising application device due to their high theoretical capacity and energy density. However, the commercialization of Li-S batteries is hindered by the rapid capacity fading caused by the shuttle effect of lithium polysulfide (LiPSs) and the sluggish redox reaction of sulfur cathodes. To address these issues, the hybrid membrane with combination of multiphasic molybdenum diselenide nanosheets (MMS) modified carbon nanotubes (MMS@CNTs) and utilized Li2S6 catholyte for Li-S batteries. The conductivity CNTs facilitate fast electronic/ionic transport, while the polarity of MMS has a strong affinity for LiPSs, effectively anchoring them, facilitating the redox conversion of lithium polysulfides, and effectively diminishing reaction barriers. The cell with MMS@CNTs displays an initial discharge capacity of 1036.2 mAh g−1 and maintains 810.5 mAh g−1 after 300 cycles at 0.2 C with 5.4 mg sulfur loading. Remarkably, even at 10.8 mg sulfur loading, the MMS@CNTs membrane displays high capacity of 8.1 mAh and maintains 6.7 mAh over 100 cycles. The results show that the efficient chemical anchoring polysulfides and catalyzing redox reaction by multifunctional MMS@CNTs hybrid composites is promising for assembling with a high sulfur loading electrode, which exhibits a superior electrochemical performance in Li-S batteries.