High-Lithium-Affinity Chemically Exfoliated 2D Covalent Organic Frameworks.
basic_science · Level V
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- Record sourced from PubMed, PMID 31155765.
- Also identified by DOI 10.1002/adma.201901640.
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Abstract
Covalent organic frameworks (COFs) with reversible redox behaviors are potential electrode materials for lithium-ion batteries (LIBs). However, the sluggish lithium diffusion kinetics, poor electronic conductivity, low reversible capacities, and poor rate performance for most reported COF materials limit their further application. Herein, a new 2D COF (TFPB-COF) with six unsaturated benzene rings per repeating unit and ordered mesoporous pores (≈2.1 nm) is designed. A chemical stripping strategy is developed to obtain exfoliated few-layered COF nanosheets (E-TFPB-COF), whose restacking is prevented by the in situ formed MnO<sub>2</sub> nanoparticles. Compared with the bulk TFPB-COF, the exfoliated TFPB-COF exhibits new active Li-storage sites associated with conjugated aromatic π electrons by facilitating faster ion/electron kinetics. The E-TFPB-COF/MnO<sub>2</sub> and E-TFPB-COF electrodes exhibit large reversible capacities of 1359 and 968 mAh g<sup>-1</sup> after 300 cycles with good high-rate capability.