An Electrochemically Stable 2D Covalent Organic Framework for High-performance Organic Supercapacitors

An electrochemically stable two-dimensional covalent organic framework,PI-COF,has been synthesized by a scalable solvothermal method.PI-COF possesses a highly crystalline structure,well-defined pores,high specific surface area,and cluster macrostructure.Thanks to these features,PI-COF can work as electrode materials in organic supercapacitors,exhibiting a specific capacitance of 163 F/g at 0.5 A/g over a wide potential window of 0-2.5 V.Moreover,PI-COF shows excellent rate performance,which can deliver 96 F/g even at a high current density of 40 A/g.Because of the high capacitance and wide potential window,PI-COF has achieved a superior energy density of 35.7 W h/kg at a power density of 250 W/kg.Most importantly,due to the remarkable electrochemical stability,the PI-COF based device shows outstanding cycling stability with 84.1%capacitance maintained(137 F/g)after 3.0×10^4 charged/discharged cycles at 1 A/g.This work should shed light on designing new COF-based electrode materials for and other electrochemical devices.