MOF-Derived Bimetal ZnPd Alloy as a Separator Coating with Fast Catalysis of Lithium Polysulfides for Li-S Batteries

Lithium-sulfur battery has a high theoretical specific capacity (1675 mAh/g), but its application is greatly hindered by the lithium polysulfide shuttling effect. In this paper, metal-organic framework (MOF)-derived ZnPd alloy nanoparticles with uniform dispersion in a nitrogen-doped three-dimensional carbon framework (ZnPd/NCF) were prepared and used as a separator coating for developing long-cycle stable lithium-sulfur batteries. The synergistic effect of lithium philophile element Zn and sulfur philophile element Pd endows the ZnPd alloy with high catalytic activity for lithium polysulfides, enabling ZnPd/NCF to rapidly adsorb and catalyze lithium polysulfides at high sulfur loadings or current densities. As a result, the Li-S cell with the ZnPd/NCF-coated separator shows an initial capacity of 916 mAh/g at 1C and 1.2 mg/cm(2) sulfur loading, with the specific battery capacity of 627 mAh/g being retained after 500 cycles. Meanwhile, a specific capacity of 1009 mAh/g (5.45 mAh/cm(2)) was achieved even at 6 mg/cm(2) sulfur loading.