Abstract
The bandgap-dependent performance of covalent organic nanosheets (CONs) as sodium-ion battery anode materials was probed by inclusion of electron-deficient benzothiadiazole (BT) units into their network. Conjugation of BT units with electron-rich moieties afforded low-bandgap materials, and a self-assembled CON morphology with a large number of insertion sites for Na+ions was realizedviasolvothermal Stille cross-coupling. The bandgap dependence of Na+storage capacity was probed by the synthesis and characterization of large-bandgap CONs, which were subsequently compared to low-bandgap CONs in terms of electrochemical behavior. Four different CONs were investigated in total to reveal that the Na+storage capacity can be improved by increasing the charge carrier conductivityviathe inclusion of BT units, while the surface area can be controlled by maintaining the material backbone. The electrode with a solvothermally prepared low-bandgap CON demonstrated stable rate capability and cycling performance while exhibiting highly enhanced reversible discharge capacity (∼450 mA h g−1) after 30 cycles at a scan rate of 100 mA g−1. To the best of our knowledge, this discharge capacity is among the best values reported so far for organic electrodes prepared without thermal treatment.
Original language | English |
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Pages (from-to) | 17790-17799 |
Number of pages | 10 |
Journal | Journal of Materials Chemistry A |
Volume | 8 |
Issue number | 34 |
DOIs | |
State | Published - 14 Sep 2020 |