Steering Yolk–Shell Nanostructures of 1D Unit‐Based Covalent Organic Frameworks as Binder Modulators

Abstract Induced by their weak chain interactions, 1D unit‐based covalent organic frameworks (1D COFs) are favorable in molecular assembly, yet their exploration in morphology engineering and related energy storage applications are still rare. Here, a series of 1D COFs based nano‐structures (i.e. yolk–shell spheres (YS‐COF), hollow spheres (HS‐COF) and solid spheres (SS‐COF)) is prepared via a solvent‐induced strategy that can be applied as binder modulators for Li‐S batteries. Specifically, they can impart enhanced mechanical properties, more adaptability to volume change, and better ability in adsorbing/catalyzing lithium polysulfide intermediates (LiPSs) to traditional PVDF binder. Remarkably, the thus‐assembled YS‐COF‐based cell displays an initial specific capacity of up to 1011 mAh g −1 at 0.5 C, which is much higher than that of HS‐COF, SS‐COF, and PVDF‐based Li‐S batteries. Even at 4 C, it still maintains a discharge specific capacity of 962 mAh g −1 and can cycle for >600 cycles. DFT calculations and finite element simulation reveal the important roles of nanomorphology and functional groups of YS‐COF in promoting electrochemical redox kinetics to boost battery performances. This strategy might provide in‐depth insights in the morphology engineering and performance optimization of 1D COFs for Li‐S batteries.