Route to a Porous Carbon Nanofiber Membrane Containing FexCy/Fe by Facile In Situ Ion-Exchange Functionalization of the PAA Carboxyl Group: Exemplified by a Supercapacitor

Abstract

In this paper, the concept of facile carboxyl in situ ion-exchange (CISIE) functionalization is utilized in preparing polyimide (PI)-derived carbon materials for the first time. Taking Fe species as an example, a high-performance FexCy/Fe composite porous carbon nanofiber (PCF) membrane is obtained by electrospinning of the PI precursor. The morphology and structure are characterized by scanning electron microscopy, X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, and other means. Then, the electrochemical performance is taken as an example to highlight the prospect of this preparation method of functional porous carbon materials. The cyclic voltammetry curves are analyzed by means of b-values, Trasatti’s method, and Dunn’s method, and it was found that porous carbon materials can show pseudocapacitance due to the introduction of Fe3+. Herein, the activated PCF-Fe electrode exhibits a high specific capacitance, which reaches 340 F g–1 at a current density of 1 A g–1 and shows a rate capability of 35.29% (120 F g–1 at 50 A g–1). In addition, PCF-Fe also shows great potential for application in self-standing electrodes. Furthermore, an assembled asymmetric supercapacitor made of PCF-Fe exhibits an energy density of 16.3 W h kg–1 at a power density of 0.6 kW kg–1 and a long cycle life. The FexCy/Fe composite PCF membranes obtained based on facile CISIE functionalization exhibit an excellent electrochemical storage performance and are expected to be utilized as electrode materials for supercapacitors.