Covalent organic framework containing dual redox centers as an efficient anode in Li-ion batteries

Covalent organic frameworks (COFs) with periodic channels and tunable chemical structures have been widely considered as promising electrode materials in rechargeable batteries. However, the design and construction of high-performance COFs-based electrodes still face some challenges in the introduction of multiple efficient redox centers as well as the reduction of dead mass. To address these issues, a unique COF containing double active centers (CN and NN) is developed as an anode in rechargeable lithium-ion batteries (LIBs). The as-prepared COF displays excellent electrochemical performance due to its remarkable structural stability and the existence of many active groups. Meanwhile, its electrochemical performance is significantly better than that of the small molecule compound or the linear polymer with the same construction units. Even at a high current density of 5 A/g, the LIBs with COF electrodes remain at a high discharge capacity of 227 mAh/g after 2000 cycles. Moreover, the distinction in electrochemical performances of these three materials is further revealed by calculation. This study illustrates the importance of molecular structure design for improving the performance of organic electrodes.