Molecular engineering of covalent organic nanosheets for high-performance sodium-ion batteries

Min Sung Kim, Minseop Lee, Min Jae Kim, Young Kyu Jeong, Jin Kuen Park, Seung Min Paek

Research output: Contribution to journalArticlepeer-review

20 Scopus citations

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 languageEnglish
Pages (from-to)17790-17799
Number of pages10
JournalJournal of Materials Chemistry A
Volume8
Issue number34
DOIs
StatePublished - 14 Sep 2020

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