Polypyrrole-Decorated Hierarchical NiCo2O4 Nanoneedles/Carbon Fiber Papers for Flexible High-Performance Supercapacitor Applications

A novel polyprrole (PPy)-decorated hierarchical NiCo2O4 nanoneedles was grown on highly conductive carbon fiber paper (CFP) for high performance asymmetric supercapacitor applications. The PPy-decorated hierarchical NiCo2O4 nanoneedle on CFP (PPy-NiCo2O4@CPF) was grown by two steps. At first, NiCo2O4 nanoneedle was grown by hydrothermal process and followed by the deposition of PPy through electrochemical method. The fabricated PPy-NiCo2O4@CPF electrode displayed the higher electrochemical performance. The specific capacitance was similar to 910 F g-1 at a current density of 1 Ag-1 and cyclic stability was similar to 88% after 10,000 cycles. To explore real performance of the electrode, we have fabricated solid state asymmetric supercapacitor using PPy-NiCo2O4@CFP as positive and nitrogen doped reduced graphene oxide (N-rGO) as negative electrodes. The fabricated asymmetric device delivered a specific capacitance of 118.6 F g-1 at a current density of 1.0 Ag-1 with a maximum energy density of 40.81 Wh Kg(-1) (at a power density of 738.27 W Kg(-1)) and maximum power density of 3746.77 W Kg(-1) (at an energy density of 13.53 Wh Kg(-1)). The impressive results suggest that flexible PPy-NiCo2O4@CFPs can be a promising electrode material for supercapacitor applications. (C) 2017 Elsevier Ltd. All rights reserved.