Extending the π‐Conjugation of a Donor‐Acceptor Covalent Organic Framework for High‐Rate and High‐Capacity Lithium‐Ion Batteries

Abstract

Abstract Realizing high‐rate and high‐capacity features of Lihium‐organic batteries is essential for their practical use but remains a big challenge, which is due to the instrinsic poor conductivity, limited redox kinetics and low utility of organic electrode mateials. This work presents a well‐designed donor‐acceptor Covalent Organic Framework (COFs) with extended conjugation, mesoscale porosity, and dual redox‐active centers to promote fast charge transfer and multi‐electron processes. As anticipated, the prepared cathode with benzo [1,2‐b:3,4‐b′:5,6‐b′′] trithiophene (BTT) as p‐type and pyrene‐4,5,9,10‐tetraone (PTO) as n‐type material (BTT‐PTO‐COF) delivers impressive specific capacity (218 mAh g −1 at 0.2 A g −1 in ether‐based electrolyte and 275 mAh g −1 at 0.2 A g −1 in carbonate‐based electrolyte) and outstanding rate capability (79 mAh g −1 at 50 A g −1 in ether‐based electrolyte and 124 mAh g −1 at 10 A g −1 in carbonate‐based electrolyte). In addition, the potential of BTT‐PTO‐COF electrode for prototype batteries has been demonstrated by full cells of dual‐ion (FDIBs), which attain comparable electrochemical performances to the half cells. Moreover, mechanism studies combining ex situ characterization and theoratical calculations reveal the efficient dual‐ion storage process and facile charge transfer of BTT‐PTO‐COF. This work not only expands the diversity of redox‐active COFs but also provide concept of structure design for high‐rate and high‐capacity organic electrodes.