An intercalation–conversion hybrid mechanism enables covalent organic frameworks with superior Li-ion storage

Abstract

Low charge storage in the intercalation reaction and large volume change induced by the conversion reaction greatly limit the practical selection of electrodes in lithium-ion batteries (LIBs). Utilizing the synergistic effects of various Li⁺ storage mechanisms to construct high energy density and long-term cycling cathodes of LIBs is significant and still challenging. Herein, a novel I₂-containing viologen-based covalent organic framework coated carbon nanotube (I-VCOF@CNT) cathode is designed by integrating the advantages of intercalation and conversion mechanisms. Moreover, the framework and pore structure of the VCOF are fully utilized for charge storage, which maximizes the utilization of the COF structure. Reflected in LIBs, I-VCOF@CNT exhibits high specific capacity, excellent rate performance, and admirable long-term cycling stability. Such a design idea can also be applied to be extensively used in other electrode materials, which provides a new insight for exploring composite materials integrating multiple reaction mechanisms.