Controlling ZIF-L morphology on polyacrylonitrile fibers via Fe doping: Fe-CoOy/carbon nanofibers for use in high-performance flexible supercapacitors

Abstract

Composite fibers derived from zeolitic imidazole frameworks (ZIFs) and polyacrylonitrile (PAN) nanofibers have gained attention as freestanding flexible electrodes for use in energy-storage devices. Herein, we decorated PAN nanofibers with Fex？Co？ZIF-L in water, as an eco-friendly solvent, using a wet chemical impregnation process followed by carbonization at 800 ℃ in Ar to produce freestanding Fex？CoOy@carbon-nanofiber (CNF) supercapacitor electrodes. The Fex？CoOy@CNF sample with the optimal Fe concentration exhibited an areal capacitance of 421.6 mF？cm？2 and a capacitance retention of 107.7% after 20,000 galvanostatic charge？discharge cycles. Flexible symmetrical supercapacitors fabricated using these materials were found to be exceptionally flexible, exhibit high energy densities, and show excellent cycling stabilities. This paper reports a well-designed energy-storage system for wearable electronics, and underscores the importance of advanced electrode materials with high performance and efficiency.