Hierarchical NiCo2S4@PANI core/shell nanowires grown on carbon fiber with enhanced electrochemical performance for hybrid supercapacitors

Rational assembly involving hetero-growth of hybrid structures consisting of multiple components with distinctive features is a promising strategy to develop materials with enhanced electrochemical performance for supercapacitors. Herein, hierarchical polyaniline-coated NiCo2S4 nanowires grown on carbon fiber (NiCo2S4@PANI/CF) were fabricated through hydrothermal method and potentiostatic deposition. The core/shell heterostructure endowed the NiCo2S4@PANI/CF composite materials with high electron diffusion efficiency and abundant accessible electroactive sites. The PANI shell improved the structural stability of the core NiCo2S4 nanowires. When employed as a free-standing electrode, the NiCo2S4@PANI/CF exhibited impressive electrochemical performances with a high specific areal capacitance of 4.74 F/cm(2) (1823 F/g) at 2 mA/cm(2) and an excellent cycling stability with capacitance retention of 86.2% after 5000 cycles. Furthermore, an asymmetric supercapacitor device was assembled using NiCo2S4@PANI/CF as positive electrode and graphene/CF as negative electrode. The resultant device delivers a high energy density of 64.92 Wh/kg at a power density of 276.23 W/kg, as well as considerable flexibility. The core/shell heterostructure design is expected to realize high-performance flexible supercapacitor for future portable and wearable electronic devices. (C) 2017 Elsevier B.V. All rights reserved.