Ultra-endurance flexible all-solid-state asymmetric supercapacitors based on three-dimensionally coated MnOx nanosheets on nanoporous current collectors

Three-dimensional (3D) porous current collector is effective in enhancing the energy density per surface area of batteries and supercapacitors due to its ability for high mass loading of active materials and efficient electron and ion transport. Herein, we report a facile method to construct a nanoporous Ni architecture on the surfaces of flexible carbon cloth (Ni@CC). By electrodeposition of ultrathin MnOx nanosheets on the 3D Ni@CC nanoporous current collectors, we achieved an areal specific capacitance of 906.6 mF cm(-2) at 1 mA cm(-2), which is much higher than 353.2 mF cm(-2) using bare CC as the current collector. Employing the 3D MnOx@Ni@CC positive electrode and a chemically converted graphene (CCG) negative electrode, we assembled a flexible all-solid-state asymmetric supercapacitor (AASC) in a Na2SO4/polyvinyl alcohol (PVA) gel electrolyte. The AASC can achieve a superior energy density of 1.16 mW h cm(-3) at a current density of 1 mA cm-2 and excellent cyclability with 81.5% capacity retention after 10,000 charging/discharging cycles. More importantly, the AASC can maintain over 85.7% of its original capacitance even after 200 bending cycles. These results demonstrate the great potential for application of 3D Ni@CC scaffolds in flexible, high performance wearable electronics and energy storage devices. (C) 2016 Elsevier Ltd. All rights reserved.