MOF derived Ni-Co-S nanosheets on electrochemically activated carbon cloth via an etching/ion exchange method for wearable hybrid supercapacitors

Abstract

Flexible electrodes with favorable architectures are urgently demanded for flexible and wearable supercapacitors with high performance. Herein, we demonstrate the rational design and preparation of hollow and ultrathin nickel cobalt sulfides nanosheets arrays on electrochemical activated carbon cloth (Ni-Co-S/ACC) for fabrication of flexible hybrid supercapacitors, where the Ni-Co-S nanosheets are derived from the metal-organic framework via an etching/ion exchange method. The Ni-Co-S/ACC electrode can deliver a very high specific capacitance of 2392 F/g at the current density of 1 A/g and good rate performance (80.3% capacitance retention at 20 A/g). The enhanced electrochemical properties should be attributed to the hydrophilic property, good conductivity and enriched redox active sites resulted from the electrochemical activated carbon cloth and the hollow and ultrathin structure of Ni-Co-S nanosheets. When a flexible hybrid supercapacitor is assembled using Ni-Co-S/ACC as positive electrode and activated carbon as negative electrode, it shows high energy density of 30.1 Wh/Kg at power density of 800.2 W/Kg as well as predominant cycling stability (82% retention after 10,000 cycles). Furthermore, the excellent flexibility and wearability of the hybrid supercapacitor could envision promising applications in high-performance wearable energy storage devices.