Iron-vanadium oxide nanoarrays on polyimide-based electrospun carbon nanofibers as high-performance free-standing electrodes for symmetric supercapacitors

The hierarchical design of three-dimensional (3D) nonarchitect hybrid nanomaterials with unique morphologies can enhance performance for energy storage applications. We prepared polyimide carbon nanofiber (PIECNF) mats from polyamic acid (PAA) nanofibers via imidization and carbonization. These mats served as substrates for growing nanostructured iron-vanadium oxide (V-Fe-O) hybrid materials using a hydrothermal method followed by calcination. The unique structure and uniform growth of V-Fe-O on conductive PIECNF synergistically reduced resistance and enhanced the electrochemical performance of electrode material (V-Fe-O@PIECNF). The optimized electrode, V-Fe-O1@PIECNF, demonstrated impressive electrochemical performance within the-1 to 0 V potential window, achieving a specific capacitance of 490 F g- 1 at a current density of 1 A g- 1, along with excellent cycling stability, retaining over 93.2 % of its initial capacitance, even after 10,000 cycles. The unique, non- agglomerated nanostructures on conductive carbon nanofiber substrates maintain their integrity during repeated charge-discharge cycles. Furthermore, the fabricated symmetric supercapacitor (V-Fe-O1@PIECNF//V- Fe-O1@PIECNF) demonstrated impressive performance, achieving an energy density (E) of 24.8 W h kg- 1 at a power density (P) of 499.9 W kg- 1, along with remarkable cycling stability over 10,000 cycles at 10 A g- 1. These results indicate the promising potential of the advanced V-Fe-O1@PIECNFelectrode in real-world energy storage applications.