High flexibility and large energy density asymmetric fibered-supercapacitor based on unique NiCo2O4@MnO2 core-shell nanobrush arrays electrode

摘要

Flexible asymmetric fibered-supercapacitors (AFS) have been considered to be excellent energy storage devices for wearable electronics, however, a major challenge as promising flexible devices lies in their relatively poor flexibility and low energy density. In this work, a kind of unique NiCo2O4@MnO2 core-shell nanobrush arrays are grown on carbon fiber (NiCo2O4@MnO2-CF) is designed and synthesized, and the electrode exhibits a remarkable areal capacitance of 8.13 F cm(-2) at 50 mA cm(-2) and exceptional capacitance retention of 93.6% after 3000 cycles. An AFS assembled with NiCo2O4@MnO2-CF and ACF (active carbon is grown on carbon fiber) as the positive and negative electrodes, respectively, delivers a wide potential window of 1.6 V and a high areal capacitance of 1.55 F cm(-2) at 2.0 mA cm(-2). Especially, the AFS exhibits excellent supercapacitive performances with a high energy density of 1.983 mW h cm(-2) (20.54 mW h cm(-3)) at a power density of 1.72 mW cm(-2) (135.1 mW cm(-3)) and a perfect stability after 8000 cycles at a current density of 50 mA cm(-2). Interestingly, the AFS shows good flexibility and could withstand the bending, folding and twisting test, and long term stability for 5000 cycles. Such an impressive AFS based on unique-structure fibrous electrodes which would be a promising candidate for using in flexible wearable micro energy storage devices. (C) 2018 Elsevier Ltd. All rights reserved.