The porous ZnCo2O4 nanosheets arrays as a binder-free electrode for high performance flexible supercapacitor materials

In this paper, a porous ZnCo2O4 nanosheet arrays (NAs)/carbon cloth (CC) binder-free anode for the flexible energy storage devices application was constructed by the hydrothermal method and subsequent annealing treatment. This anode electrode material shows multistage pore distribution that can provide numerous ways for the transport of ions and electrons. As a supercapacitor electrode, the flexible ZnCo2O4/CC electrode indicates a high specific capacitance (1790 F/g at the current density of 1 A/g), good rate performance, and excellent cycle properties (99.4% capacitance retention after 10,000 cycles). Besides, the flexible electrode also displays good mechanical flexibility. A solid-state asymmetric flexible supercapacitor device was assembled with the ZnCo2O4/CC electrode as the positive electrode and the carbon nanotube (CNTs)/CC as the negative electrode. This asymmetric device delivers high energy density of 47.1 Wh/kg (power density 800 W/kg) and power density of 12,000 W/kg (energy density 28.3 Wh/kg) with the potential window 0–1.6 V. These results indicate that the ZnCo2O4/CC flexible electrode with high electrochemical performance adjusts for environment-friendly and low-cost energy storage devices in the future.