Synthesis of Bi 2 Se 3 Nanosheets on COF Surfaces as Cathode for Lithium‐Sulfur Batteries: Synergistic Mechanism of Anchoring and Catalyzing Polysulfides

Lithium‐sulfur (Li‐S) batteries are one of the popular choices for the high energy storage systems due to their high theoretical energy density, cheap raw materials, and environmental friendliness. This work adopts a hydrothermal method to prepare covalent organic frameworks (COFs). Bi 2 Se 3 nanosheets are synthesized on COFs to obtain Bi 2 Se 3 /COFs composites serving as sulfur hosts. The porous COFs accommodate active sulfur and restrain the diffusion and migration of lithium polysulfides simultaneously. Furthermore, polar Bi 2 Se 3 immobilizes lithium polysulfides via chemical adsorption and efficiently alleviates the shuttle effect. Its layered nanostructure not only improves the structural stability of the cathode, but also endows the composites with superior electrical conductivity to accelerate the the redox reaction of sulfur. The results illustrate that the S/Bi 2 Se 3 /COFs electrode shows a remarkable initial discharge specific capacity of 961.2 mAh g −1 at 0.5 C. After 700 cycles, the capacity decay rate is 0.047% per cycle, showing excellent cycle stability. Therefore, the Bi 2 Se 3 /COFs are a desirable sulfur‐loading host for high‐performance Li‐S batteries.