Facile preparation of porous nickel oxide membrane for flexible supercapacitors electrode via phase-separation method of polymer

In this article, a porous flexible membrane electrode of nickel oxide is developed by a facile method based on liquid-liquid phase-separation. The effects of the membrane components on structures and electrochemical behaviors of membrane electrode are investigated. The results reveal that nano NiO and conducting graphite are imbedded into the polymer membrane of polyethersulfone to form a flexible hybrid membrane (M-NiO-G), which shows the highest specific capacitance of 794.0 F/g at a current density of 1.0 A/g. The asymmetrical supercapacitor device based on the as-synthesized of M-NiO-G (positive electrode) and activated carbon membrane (negative electrode) exhibits a high specific capacitance of 154.0 F/g at a current density of 0.2 A/g. The coulombic efficiency remains about 95.0%, and the capacitance retention is 84.8% after 5000 charging-discharging cycles at 1.0 A/g. The energy density of the asymmetrical supercapacitor device reaches 39.6 Wh/kg at a power density of 516.9 W/kg, still remains 20.0 Wh/kg at a high power density of 2567.4 W/kg in the potential window from 0 to 1.36 V in 6 M KOH aqueous solution.