Flexible binder-free hierarchical copper sulfide/carbon cloth hybrid supercapacitor electrodes and the application as negative electrodes in asymmetric supercapacitor

Abstract

In order to provide necessary electronic energy supply to portable wearable electronics, supercapacitor electrode with flexibility and high energy density is needed. In this paper, a hierarchical structure spionkopite has been in situ grown onto the electrochemical functional surface of commercial carbon cloth by a hydrothermal process. Combined from the hybrid energy storage process of battery-type and capacitance-type reactions of ultrathin Cu1.4S nanoplates, high specific capacitance, rate performance, and good cyclic performance are achieved. As a result, the Cu1.4S@CC electrode exhibits a high specific capacitance and specific capacity of 485 F g−1 and 727.5 C g−1 under 0.25 A g−1 based on the mass of Cu1.4S and maintains 66% initial capacitance even under the high current density to 10 A g−1. Besides, good mechanical robustness and electrochemical stability (retention of 80.2% capacitance after 1000 cycles) have been demonstrated. An asymmetric supercapacitor has been constructed by the Cu1.4S@CC negative electrode and nickel-based MOF positive electrode to study the practical electrochemical performance of Cu1.4S@CC electrode. The operating voltage has been effectively improved to 1.8 V in aqueous electrolyte, and the energy density could reach 52.5 Wh kg−1 at the power density of 0.9 kW kg−1.