New design of all-solid state asymmetric flexible supercapacitor with high energy storage and long term cycling stability using m-CuO/FSS and h-CuS/FSS electrodes

Highlights: • The first investigation of m-CuO120/FSS//h-CuS100/FSS AFSS-SCs device. • The AFSS-SCs device exhibits excellent specific capacitance of 123 F g^-1 at scan rate of 5 mVs⁻¹. • The AFSS-SCs device glows red, yellow and green LEDs for more than 3 min. -- Abstract: Nanorods of copper oxide and nanoribbons of copper sulfide electrodes are synthesized by simple hydrothermal and successive ionic layer adsorption and reaction methods, respectively. The surface of electrode material is altered with reaction temperature and successive ionic layer adsorption and reaction cycles. The monoclinic copper oxide exhibits electrochemical features as, specific capacitance of 630 F g⁻¹ at 5 mV s⁻¹, energy density of 64.5 W h kg⁻¹ and power density of 4.1 kW kg⁻¹. Hexagonal copper sulfide shows specific capacitance of 924 F g^-1, energy density of 67 W h kg⁻¹ and power density of 3.3 kW kg⁻¹. Furthermore, capacity retentions of m-CuO120/FSS and h-CuS100/FSS are 89.5 and 87.4% after 2000 charge-discharge cycles, respectively. Herein, for the first time, a new design of asymmetric supercapacitor by new combination of positive and negative electrodes using polyvinyl alcohol-potassium hydroxide gel electrolyte is reported. The maximum specific capacitance of 123 F g^-1 is achieved at 5 mV s⁻¹, with energy density of 22.8 W h kg⁻¹, power density of 2.5 W kg⁻¹ and the capacity retention of 96.3% after 5000 charge discharge cycles for asymmetric device. The actual demonstration of asymmetric m-CuO120/FSS//h-CuS100/FSS device realizes the charge storing capacity of device and future scope of device in portable electronics.