Catalytic Co9S8 decorated carbon nanoboxes as efficient cathode host for long-life lithium-sulfur batteries

摘要

Lithium sulfur(Li-S)batteries with high specific capacity and energy density can bring enormous opportunities for the nextgeneration energy storage systems.However,the severe dissolution and shuttle effect of lithium polysulfides(LiPSs)is still the key issue that seriously impedes the development of practical Li-S batteries.Here,polar Co9S8 inlaid carbon nanoboxes(Co9S8@C NBs)have been investigated as cathode host for high-performance Li-S batteries.In this integrated structure,Co9S8 nanocrystals not only provide strong chemisorptive capability for polar LiPSs,but also act as a catalyst to accelerate polysulfide redox reactions;while carbon nanobox with large inner space can offer enough space to relieve the volume expansion and physically confine LiPSs’dissolution.As a result,the S/Co9S8@C NBs cathode exhibits high specific capacity at 1C and the capacity retention was~83%after 400 cycles,corresponding to an average decay rate of only~0.043%per cycle.