ZIF-8 Template-Assisted Synthesis of Polyimide-Derived Nitrogen-Oxygen Co-doped Porous Carbon Microspheres for Supercapacitors

Abstract

Nitrogen-oxygen co-doped porous carbon microspheres were synthesized through hydrothermal and carbonization processes using polyimide (PI) as the carbon precursor and a nitrogen-oxygen source. ZIF-8 was also used as the template. When the carbonization temperature reached 800°C, the porous carbon microspheres displayed a unique 3D sea urchin-like morphology, a high specific surface area (782.3 m²/g), and good nitrogen and oxygen doping contents (6.62 and 11.92 at %, respectively). Electrochemical testing showed that when the scanning rate was 0.5 A/g, the material achieved a specific capacitance of 330.5 F/g, and the capacitance retention rate of the electrode material was 73.5% when the current density reached 10 A/g. Furthermore, the symmetrical supercapacitor assembled with this electrode had an operating voltage window that extended to 1.8 V and provided an energy density of 20.5 W h/kg at a power density of 400 W/kg. This method of preparing high performance nitrogen-oxygen co-doped carbon electrode materials provides an idea for the application of insulating polymers in the field of energy storage.