Bi2S3 Confined by Covalent Organic Frameworks Enables High‐Rate High‐Capacity Potassium Storage

Abstract Potassium‐ion hybrid capacitors (PIHCs) are highly promising as an energy‐storage system. However, the rate performance and cycling performance of most materials with high capacity cannot simultaneously meet the requirements of PIHCs. In this work, a composite material of Bi 2 S 3 nanoparticles in situ confined within a sulfur‐doped covalent organic framework (COF) and combined with graphene (Bi 2 S 3 @SCOF/G) is synthesized. Due to the synergistic effect of the stability of COF to buffer large mechanical stresses and the high electronic conductivity of graphene, the Bi 2 S 3 @SCOF/G anode reveals a high reversible capacity (503.8 mAh g −1 at 100 mA g −1 after 100 cycles) and favorable rate performance (223.9 mAh g −1 even at 5000 mA g −1 ). Furthermore, the PIHCs assembled with activated carbon show excellent energy density and cycling performance, indicating their potential for practical applications.