Curvature Defect Engineering towards High Performance COF-based Cathode in Lithium-ion Batteries

Abstract

Covalent organic frameworks (COFs), a type of functional-oriented porous material, show great potential in rechargeable batteries owing to well-defined ions channels and flexible framework design. However, the active sites in COFs are almost impossible to be fully utilized caused by the insufficient electron transport or ions diffusion. Here, a defect-rich COF@CNT cathode (RBT-COF@CNT-50) was designed by curvature defect engineering to enhance electrochemical reaction kinetics. The synergistic effect of the defect-rich D-A framework with CNT interlaced network endows RBT-COF@CNT-50 higher electron conductivity of 2.65 × 10−4 S m−1. More defects emergence with polar functional groups in RBT-COF@CNT caused by the curvature-induced effect contribute to faster ions diffusion. Consequently, RBT-COF@CNT-50 delivers higher reaction rate of 1.49 × 10−6 mol s−1 m−2. As excepted, RBT-COF@CNT-50 reveals a high specific capacity of 302 mAh g−1 at 0.1 A g−1. It also displays excellent long-term cycling performance with 148 mA g−1 at 2 A g−1 for continuously 2000 cycles and 124 mA g−1 with capacity attenuation rate of 0.004% per cycle at 10 A g−1, outperforming most reported COFs/carbon composites cathodes. This work offers in-depth insights in constructing high performance COF-based cathode by enhancing electrochemical reaction kinetics within a curvature defect engineering.