Theoretical study of thiophene-inserted COF as high performance anode material for Li-ion battery

Abstract

Molecular tailoring is necessary to improve covalent organic frameworks’ (COFs) chemical property and then the performance of COFs as anode material in lithium ion battery (LIB). In this work, thiophene-inserted BPT-COF was constructed according to the synthesized BP-COF. Density functional theory was employed to investigate the Li-ion adsorption and diffusion on BP-COF and BPT-COF. The results show that both COFs exhibit thermal and mechanical stability and an appreciated theoretical capacity can be expected. The electronic structure analysis hints that the introduced thiophene group is beneficial for Li-ion adsorption and diffusion because of the increased HOMO energy, the narrowed band gap, the lower reorganization energy and the localization of charge redistribution. The smaller energy barrier of Li-ion diffusion on BPT-COF also indicates that inserted thiophene group can evidently promote Li-ion diffusion process. All the calculations show that thiophene-inserted BPT-COF is potential high performance anode material for LIB.