NiCoO2 and polypyrrole decorated three-dimensional carbon nanofiber network with coaxial cable-like structure for high-performance supercapacitors

Abstract

Designing optimized nano-sized architecture is a promising approach to prepare high-performance electrode materials for supercapacitors. In this work, a hierarchical multi-shelled structure has been successfully synthesized, which consists of a 3D carbon nanofiber network as a supporting scaffold prepared by carbonization of aramid nanofiber aerogel, an intermediate polypyrrole (PPy) bonding layer and a NiCoO2 outer shell, just like a coaxial cable in the structure. The intermediate PPy layer facilitates the uniform deposition of NiCoO2 by providing more anchor sites, and enhances the electrical contact between carbon nanofiber network and NiCoO2 shell due to its high conductivity and good compatibility with two different substances. The synergistic effect of the hierarchical configuration endows the electrode material with a high specific capacitance of 1037 F g−1at 1 A g−1and excellent cycling stability (∼89% of initial capacitance after 7000 cycles). Moreover, an asymmetric supercapacitor based on the composite and activated carbon achieves a high energy density of 37.7 Wh kg−1 at a power density of 465 W kg−1 in 1.65 V. This work may provide a feasible strategy to design high-performance hybrid electrodes for energy storage devices.