A new metallic composite cathode originated from hyperbranched polymer coated MOF for High-performance Lithium-Sulfur batteries

Abstract

To improve the polysulfides redox conversion and mitigate the shuttle effect for lithium-sulfur (Li-S) batteries, a hyperbranched polymer coated MOF-derived zirconium nitrogen oxides and N-doping carbon composites (Zr2N2O/NC-6) are designed and prepared by pyrolytic method. Thanks to some advantages of this type of new composites including fast lithium-ion transport, lithium polysulfides (LiPSs) anchoring and multiple functional sites, the cells with S/Zr2N2O/NC-6 cathode exhibit good cycle stability (the capacity retention is 81.8% at 1C after 300 cycles) and rate capability (566.8 mAh g−1 at 5C). More importantly, even if the sulfur loading is up to 8.16 mg cm−2 and low electrolyte/sulfur (E/S) ratio (7.79 µL mg−1), the cells with S/Zr2N2O/NC-6 cathode deliver an initial area capacity of 7.2 mAh cm−2 and the capacity also can maintain at 5.34 mAh cm−2 after 80 cycles at 0.2C, which are much better than the commercial lithium-ion batteries. This work exhibits a MOF-derived novel material Zr2N2O/NC used as the sulfur host for the first time, which can have a guiding role in designing multifunctional materials with adsorption, ion transport and catalytic features for the high-performance lithium sulfur batteries with application potential.