Creating Edge Sites within the 2D Metal-Organic Framework Boosts Redox Kinetics in Lithium–Sulfur Batteries

摘要

Lithium–sulfur batteries have received extensive interest owing to theirexceptionally high energy density. Nonetheless, their practical implementationis still impeded by the shuttle effect of polysulfides and sluggish conversionkinetics. Considering that, a porous 2D defective zeolitic imidazolateframework-7 (ZIF-7) with abundant active edges is rationally designed asmultifunctional sulfur carriers for Li–S batteries. The 2D ZIF-7 enablesuniform distribution of sulfur and rapid Li-ion diffusion, while rich edgesfacilitate sufficient exposure to active sites capturing and catalyzing polysulfides.In addition, the nitrogen defects on edge sites can further acceleratethe transformation of polysulfides and decrease the energy barrier of Li_2Sdecomposition. Consequently, the Li–S batteries demonstrate surprisinglypractical prospects with a stable capacity of 676.9 mAh g~(?1) over 500 cycles at1 C (capacity retention rate = 72.3). When assembled into a pouch cell at2.3 mg cm~(?2), it still exhibits a high capacity of 901.1 mAh g?1 after 100 cyclesat 0.1 C. This work offers a rational structural design strategy to tackle thechallenges of the sulfur cathode.