NiCoSe4@CNFs derived from MOF compounds enabling robust polysulfide adsorption and catalysis in Li-S batteries

The availability of lithium sulfur (Li-S) batteries is significantly constrained by the severe shuttle effect and sluggish conversion kinetics of polysulfides (LiPSs). Here, we construct the catalytic NiCoSe4/carbon nanofibers interlayer composite (NiCoSe4 @CNFs) to restrict shuttle effect and accelerate the polysulfides conversion. The NiCoSe4 derived from metal organic framework (MOF) retains the advantage of CoSe2 in chemical adsorption for polysulfide, and Ni doping offers superior electrocatalytic activity. Meanwhile, the carbonization of MOF ensures the NiCoSe4 superior electrical contact with the derived carbon materials. In addition, CNFs build conductive carbon matrix for the growth of NiCoSe4 on the surface to facilitate the electron transfer during charging and discharging process. Benefit from the unique structure, NiCoSe4 @CNFs as interlayer can quickly and effectively carry out the strategy of polysulfides adsorption followed by simultaneously catalysis. Batteries with a NiCoSe4 @CNFs interlayer can deliver excellent performance with a stable cycle performance after 500 cycles (residual capacity of 74 %) at 2 C and a high discharge specific capacity of 1019.5 mAh g−1 at 0.5 C. Achieving robust polysulfide adsorption and electrocatalytic activity in NiCoSe4/carbon nanofibers interlayer opens previously unexplored avenues towards advanced separation technologies and energy-harvesting devices.