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 × 104 charged/discharged cycles at 1 A/g. This work should shed light on designing new COF-based electrode materials for supercapacitors and other electrochemical devices.