Olefin-Linked Covalent Organic Framework as Flexible Thin-Film Electrode for High-Performance Micro-Supercapacitor.

Developing effective synthetic strategies as well as enriching functionalities for sp(2)-carbon-linked covalent organic frameworks (COFs) still remains a challenge. Now, taking advantage of a variant of Knoevenagel condensation, a new fully conjugated COF (g-C34N6-COF) linked by unsubstituted C=C bonds was synthesized. Integrating 3,5-dicyano-2,4,6-trimethylpyridine and 1,3,5-triazine units into the molecular framework leads to the enhanced pi-electron communication and electrochemical activity. This COF shows uniform nanofibrous morphology. By assembling it with carbon nanotubes, a flexible thin-film electrode for a micro-supercapacitor (MSC) can be easily obtained. The resultant COF-based MSC shows an areal capacitance of up to 15.2 mF cm(-2), a high energy density of up to 7.3 mWh cm(-3), and remarkable rate capability. These values are among the highest for state-of-the-art MSCs. Moreover, this device exhibits excellent flexibility and integration capability.