3D catalytic MOF-based nanocomposite as separator coatings for high-performance Li-S battery

Abstract

Lithium sulfur (Li-S) battery is regarded as one of the most promising next generation high-energy storage systems. However, the shuttle effect and sluggish redox kinetics of lithium polysulfides always compromise the cycling performance of Li-S batteries. Herein, an effective strategy is presented to fabricate high-performance Li–S batteries using a 3D network-like nanocomposite of Co/NCNS/CNT, which is obtained via the well-distributed composition of the carbon nanotubes (CNTs) (in situ formed and added) with nitrogen-doped carbon nanosheets (NCNS) as well as Co nanoparticles from carbonization of the nitrogen-rich bio-MOF-100 nanosheets at an inert atmosphere. Owing to good sulphiphilicity, excellent conductivity and high catalytic activity from Co-Nx and Co nanoparticles, Co/NCNS/CNT nanocomposite could effectively adsorb and catalyze the fast conversion of lithium polysulfides. When serving as the separator coating for Li-S cells, the cell shows excellent performances with an initial capacity of 972.4 mAh/g at 2C under a sulfur loading of 2.0 mg/cm2, and excellent cycling stability with the capacity decay of 0.05% per cycle during the 1000 long-term cycles. Furthermore, even at a high sulfur loading of 5 mg/cm2, the specific capacity of 522.1 mAh/g (2.61 mAh/cm2) can be maintained after 500 cycles at 1 C, thus providing a promising path toward advanced Li–S batteries.