A new two-dimensional covalent organic framework with intralayer hydrogen bonding as supercapacitor electrode material

A new two-dimensional covalent organic framework (DBT-MA-COF) is designed and synthesized via Carbon-Nitrogen coupling reaction by using 2,5-dibromothiophene (DBT) and melamine (MA) as the monomers. The C-H-center dot N intralayer hydrogen bonding exists in the structure of DBT-MA-COF so that a plane rigid structure can be maintained. The material exhibits a quasi-reversible redox process caused by triazine units and the transformation of the quinone and aromatic structures to make the DBT-MA-COF possess pseudocapacitive characteristics. DBT-MA-COF has high heteroatom content for the existence of triazine and thiophene units, which can accelerate the transfer of electrolyte ions on the surface of DBT-MA-COF electrode and improve the solution conductivity of the material. The assembled asymmetric supercapacitor DBT-MA-COF//C-CTS ASC has a high energy density of 32.1 W h kg(-1) with the power density of 800 W kg(-1). The cycle life of the device is excellent which can reach 83% even after 30,000 continuous galvanostatic charge-discharge cycles. The strategy in this work provides a line of thinking to design and prepare new COFs used as long life and pseudocapacitive supercapacitor materials.

Automated summary

The newly designed DBT-MA-COF, synthesized via Carbon-Nitrogen coupling reaction, exhibits quasi-reversible redox process and pseudocapacitive characteristics. With high heteroatom content, it shows improved solution conductivity and high energy density in asymmetric supercapacitor configuration.