The Design of the NiN/NbN Heterostructure as Bifunctional Adsorption/Electrocatalytic Materials for Lithium-Sulfur Batteries.

Lithium-sulfur (Li-S) batteries are hindered by the sluggish electrochemical kinetics and poor reversibility of lithium polysulfides (LiPSs), which limits their practical energy density and cycle life. In order to address this issue, a novel NiN/NbN heterostructure was synthesized via electrospinning and nitridation as a functional coating for polypropylene (PP) separators. Adsorption experiments were conducted in order to ascertain the heterostructure's superior affinity for LiPSs, thereby effectively mitigating their shuttling. Studies of LiS nucleation demonstrated the catalytic role of the substance in accelerating the deposition kinetics of LiS. Consequently, Li-S cells that employed the NiN/NbN-modified separator were found to achieve significantly enhanced electrochemical performance, with the cells delivering an initial discharge capacity of 1294.4 mAh g at 0.2 C. The results demonstrate that, after 150 cycles, the cells retained a discharge capacity of 796.2 mAh g, corresponding to a low capacity decay rate of only 0.25% per cycle. In addition, the rate capability of the cells was found to be improved in comparison to control cells with NiNbO-modified or pristine separators.