Nitrogen-rich covalent organic frameworks with multiple carbonyls for high-performance sodium batteries

Abstract

Covalent organic frameworks with designable periodic skeletons and ordered nanopores have attracted increasing attention as promising cathode materials for rechargeable batteries. However, the reported cathodes are plagued by limited capacity and unsatisfying rate performance. Here we report a honeycomb-like nitrogen-rich covalent organic framework with multiple carbonyls. The sodium storage ability of pyrazines and carbonyls and the up-to twelve sodium-ion redox chemistry mechanism for each repetitive unit have been demonstrated by in/ex-situ Fourier transform infrared spectra and density functional theory calculations. The insoluble electrode exhibits a remarkably high specific capacity of 452.0 mAh g −1 , excellent cycling stability (~96% capacity retention after 1000 cycles) and high rate performance (134.3 mAh g −1 at 10.0 A g −1). Furthermore, a pouch-type battery is assembled, displaying the gravimetric and volumetric energy density of 101.1 Wh kg −1 cell and 78.5 Wh L −1 cell , respectively, indicating potentially practical applications of conjugated polymers in rechargeable batteries.

Covalent–Organic Frameworks: Advanced Organic Electrode Materials for Rechargeable Batteries

“…[ 68–72 ] Through the reaction between tetraminophenone and cyclohexanehexaone, Chen and co‐workers reported a honeycomb‐like nitrogen‐rich covalent–organic framework (TQBQ‐COF) with multiple functional groups as the cathode in SIBs (Figure 2b). [ 73 ] Due to the adjacent environment of N and O atoms, there exists a simultaneous coordination of N and O to the Na + ions. Hence, for the organics with multiple redox sites, both pyrazine (CN) units and carbonyl (CO) groups will exhibit revisable redox activity during the electrochemical energy storage, which might shed light on the design of COFs electrode materials in the future.…”

Covalent Organic Frameworks for Next‐Generation Batteries

“…Currently, COFrelated materials, with the advantages of structural diversity, environmental friendliness and designability, are expected to be promising electrode materials for SIBs. [49][50][51][52][53] The thickness and stability of COFs has a huge impact on their sodium storage performance. Lu and co-workers reported the redox and tunable stability of radical intermediates in covalent organic frameworks (DAAQ-COF), which are regarded as an anode material for SIBs with a high capacity and long cycle stability.…”

“…Chen et al designed and synthesized a new covalent organic framework (TQBQ-COF) with triquinoxaline and benzoquinone (TQBQ) units through the triple condensation reaction between tetraaminobenzophenone (TABQ) and cyclohexanehexanone (CHHO). [53] TQBQ-COF was based on carbonyl and pyrazinyl groups as the redox active sites for sodium storage, so it can achieve a theoretical capacity of up to 515 mAh g À 1 (Figure 4a). The structure of TQBQ-COF was simulated by density functional theory (DFT).…”

“…The capacity is calculated based on the mass of the full cell. Reproduced with permission from Ref [53]. Copyright 2020, Nature Publishing Group.…”

Molecular Design Strategy for High‐Redox‐Potential and Poorly Soluble n‐Type Phenazine Derivatives as Cathode Materials for Lithium Batteries

“…The development of rechargeable batteries with organic electrode materials has become increasingly attractive to drive down cost and boost capacity/energy density to satisfy the demand of electrochemical energy storage . Organic electrode materials, which consist of natural abundant elements, allow precisely controllable synthesis/production as well as circular economy development . Among the variety of organics, phenazine (PZ) derivatives, which are heterocyclic N‐containing metabolites in living organisms, have been studied as promising organic cathode materials because of their biotic nontoxicity and low cost .…”