Schiff-Base Covalent Organic Framework/Carbon Nanotubes Composite for Advanced Potassium-Ion Batteries

Covalent organic frameworks (COFs) are attractive candidates for low-cost potassium-ion battery (PIB) electrode materials due to their inherent porosity, well-organized channel structure, and excellent thermochemical stability. Herein, a Schiff-base COF/carbon nanotubes (TP-COF/CNTs) composite is synthesized by a condensation reaction between 1,3,5-triformylbenzene (TFB) and p-phenylenediamine (PPD) on the surface of CNTs as an anode for PIBs. The introduction of CNTs not only assumes the role of a conductive network in improving the kinetics of potassium ions (K+) but also induces the growth of COFs through π–π interactions, leading to more exposure of more active sites. In consequence, the core–shell-structured TP-COF/CNTs exhibit advanced K storage performance (290 mA h g–1 after 200 cycles at 0.1 A g–1) and fine rate capability (169 mA h g–1 at 1 A g–1), outperforming most COF materials. Furthermore, X-ray photoelectron spectroscopy, ex situ infrared analysis, and density functional theory calculations indicate that the storage of K+ depends on electroactive C═N groups and the π–K+ effect. This work supplies PIBs with a promising high-performance anode material and may benefit the development of COFs for PIBs.