Freestanding ZIF‐9‐Derived Cobalt Carbon Nanofibers for Supercapacitor Electrodes

Abstract

A zeolitic imidazolate framework (ZIF‐9) was synthesized via solvothermal reaction using cobalt (Co) salt and benzimidazole ligands in the presence of polyacrylonitrile. The precursor was electrospun to form carbon nanofibers (CNFs) creating freestanding, binder‐free supercapacitor electrodes. Polyvinylpyrrolidone (PVP) and NaCl were added to the precursor solution to reduce fiber diameter and improve structural integrity during high‐temperature annealing. The Co/CNF sample achieved an areal capacitance of 316 mF cm −2 and an energy density of 0.043 mWh cm −2 at a current density of 1 mA cm −2 . The addition of NaCl and PVP reduced fiber diameter by 30% and increased capacitance by 3.6 times. The optimal sample maintained 96.2% of its capacitance over 10,000 charge/discharge cycles, demonstrating strong electrochemical stability. Symmetrical pouch cells with the developed electrodes powered a light‐emitting diode and a humidity/temperature sensor, demonstrating their potential in portable electronics.