Flexible Cross-Linked Electrospun Carbon Nanofiber Mats Derived from Pitch as Dual-Functional Materials for Supercapacitors
Xiaodong Tian, Yiting He, Yan Song, Tao Yang, Xiao Li, Zhanjun Liu
Abstract
Freestanding and binder-free electrospun carbon nanofiber mats with a cross-linked structure (CLCF) were fabricated by using pitch as the precursor. The cross-linked structure can be tuned easily by controlling the preoxidation degree of electrospun nanofibers. This cross-linking strategy can not only convert low value pitch into economical efficient energy storage materials but also reduce contact resistance and enhance ion diffusion kinetics of the as-obtained CLCF by reducing the fiber diameter, balancing porous structure, and conductivity. The CLCF electrode with a moderate preoxidation degree exhibits remarkable rate performance (160 F g–1 at 100 A g–1, 85.6% of its initial capacity at 1 A g–1) in 6 M KOH aqueous electrolyte, compared with carbon nanofibers without and with an overdose of cross-linked structure. Moreover, as a scaffold for depositing NiMoO4, impressive electrochemical performance can be achieved. The assembled asymmetrical device based on CLCF and NiMoO4-anchored CLCF delivers a stable working voltage of 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 intriguing electrochemical performance can be credited to the cross-linked fibrous structure that endows the CLCF with rapid ion diffusion kinetics and fast electron transfer as well as robust structural stability to bear the volume fluctuation of NiMoO4 during the repeated charge/discharge process. Therefore, our work provides a new strategy to design high performance carbon nanofiber mats with a cross-linked structure as a dual-functional material for supercapacitor devices by using pitch.