Rational design of integrated CuO@CoxNi1-x(OH)2 nanowire arrays on copper foam for high-rate and long-life supercapacitors

Rational electrode architectural design, favorable electrode composition, and versatile synthesis approach play a significant role in developing advanced electrodes for high-performance supercapacitor. In this work, we report a facile approach for fabricating 1D hierarchical CuO@CoxNi1-x(OH)(2) nanowire arrays grown on 3D highly conductive copper foam. The optimized CuO@Co0.2Ni0.8(OH)(2) electrode delivers an ultrahigh specific capacity of 374.7 mAh g(-1) at 2 A g(-1) with exceptional rate capability (301.7 mAh g(-1) at 50 A g(-1)) and remarkable cycling stability (95.9% after 10 000 cycles at 50 A g(-1)). A flexible asymmetric solid-state supercapacitor (ASC) is fabricated using the optimized CuO@Co-0.2-Ni-0.8(OH)(2) as the positive electrode, activated carbon-coated nickel foam as the negative electrode, and polyvinyl alcohol/KOH gel as electrolyte. The flexible ASC operating with a potential window of 0-1.6 V delivers an energy density of 46.5Wh kg(-1) with a power density of 526.9 W kg(-1). The ASC also exhibits excellent cycling stability with a capacity retention of 84.3% after 10 000 cycles at a current density of 7 Ag-1. (C) 2018 Elsevier Ltd. All rights reserved.