Flexible Cross-Linked Electrospun Carbon Nanofiber\nMats Derived from Pitch as Dual-Functional Materials for Supercapacitors

Abstract

Freestanding and binder-free electrospun\ncarbon nanofiber mats\nwith a cross-linked structure (CLCF) were fabricated by using pitch\nas the precursor. The cross-linked structure can be tuned easily by\ncontrolling the preoxidation degree of electrospun nanofibers. This\ncross-linking strategy can not only convert low value pitch into economical\nefficient energy storage materials but also reduce contact resistance\nand enhance ion diffusion kinetics of the as-obtained CLCF by reducing\nthe fiber diameter, balancing porous structure, and conductivity.\nThe CLCF electrode with a moderate preoxidation degree exhibits remarkable\nrate performance (160 F g^–1 at 100 A g^–1, 85.6% of its initial capacity at 1 A g^–1) in\n6 M KOH aqueous electrolyte, compared with carbon nanofibers without\nand with an overdose of cross-linked structure. Moreover, as a scaffold\nfor depositing NiMoO₄, impressive electrochemical performance\ncan be achieved. The assembled asymmetrical device based on CLCF and\nNiMoO₄-anchored CLCF delivers a stable working voltage\nof 1.6 V with a high energy output of 14.9 Wh kg^–1 and a maximum power density of 14.3 kW kg^–1. The\nintriguing electrochemical performance can be credited to the cross-linked\nfibrous structure that endows the CLCF with rapid ion diffusion kinetics\nand fast electron transfer as well as robust structural stability\nto bear the volume fluctuation of NiMoO₄ during the repeated\ncharge/discharge process. Therefore, our work provides a new strategy\nto design high performance carbon nanofiber mats with a cross-linked\nstructure as a dual-functional material for supercapacitor devices\nby using pitch.