Functionalized Graphene Quantum Dots Modified Dioxin‐Linked Covalent Organic Frameworks for Superior Lithium Storage

Covalent organic framework, as an emerging porous nano‐frame structure with pre‐designed structure and custom properties, has been demonstrated as a prospective electrode for rechargeable Li‐ion batteries. For improving the reversible capacity and long‐term cycle stability of COF materials, we propose a GQDs modified COF material (COF‐GQDs) and apply it as the anode for LIBs for the first time. This COF‐GQDs electrode delivers enhanced long‐term cycling performance with a large capacity of ∼820 mAh g−1 after 300 cycles at 100 mA g−1 and an improved rate performance. The enhanced lithium‐storage performance, in terms of obvious‐shortened activation process and high reversible capacities, can be attributed to the modification of carboxyl GQDs, which would activate more active sites (activated C=C groups from benzene rings) for lithium‐storage, and provide fast lithium‐ion transportation kinetic. Besides, the decreased interphase resistance, enhanced electronic conductivity, and prevented aggregation of needle‐flake COF structure, originated from the addition of GQDs, which lead to the enhanced improved cycling stability of the COF‐GQDs electrode. This manuscript can promote the further exploration on the design of COF‐related materials with modification of functionalized carbonaceous materials to achieve enhanced lithium‐storage properties for next‐generation energy storage. Functionalized graphene quantum dots (GQDs) modified dioxin‐linked covalent organic frameworks (COF) are fabricated and applied as anode material of lithium‐ion battery for the first time. The modification of carboxyl GQDs leads to more active sites, fast lithium‐ion transportation kinetics, and enhanced electronic conductivity, resulting in enhanced lithium‐storage properties for the graphene quantum dots modified covalent organic frameworks (COF‐GQDs) electrode