Metal-Organic Framework-Derived NiSe2 Nanoparticles on Graphene for Polysulfide Conversion in Lithium-Sulfur Batteries

The rechargeable lithium-sulfur battery is regarded as one of the most promising secondary batteries because of its superior energy density and cost-effective raw materials. However, it still faces many challenges, the most important of which lies in the notorious polysulfide shuttle effect. Herein, we design and fabricate graphene-supported, metal-organic framework (MOF)-derived NiSe2 nanoparticles (rGO-NiSe2) as separator modifiers. The NiSe2 nanoparticles with high catalytic activity can effectively adsorb polysulfides and accelerate their conversion. A highly conductive graphene as a catalyst substrate can effectively decrease the internal resistance of the battery. In addition, the intercalation growth of octahedral MOF-derived NiSe2 nanoparticles between graphene sheets provides abundant active sites for polysulfides. The battery with a rGO-NiSe2-modified separator provides an initial capacity of 1356.5 mAh g(-1) at 0.2 C, and only experiences a low capacity decay rate of 0.079% per cycle during 500 cycles of operation at 1 C. Even under a relatively high loading amount of 5.2 mg cm(-2), the battery can still yield a high specific capacity of 774.3 mAh g(-1) at 0.5 C and a capacity retention of 84% after 100 cycles.