Enhanced Supercapacitive Performance Of Reduced Graphene Oxide By Incorporating Nico2o4 Quantum Dots Using Aqueous Electrolyte

We have prepared nanocomposite films of reduced graphene oxide (rGO) and nickel cobalt oxide quantum dots (NCO-QDs) by chemical method, and these are represented by NCO-rGO. Different nanocomposite films have been formed by varying the ratio of NCO-QDs and rGO. The obtained value of the specific capacitance of the nanocomposite (NCO5-rGO(1.5)) is 265 F g(-1) (260 C g(-1)) at 0.73 A g(-1) which is much higher than rGO alone (96 F g(-1) at 0.33 A g(-1)). As the asymmetric/hybrid configuration also enhances the potential window, so in this work, we have fabricated an asymmetric supercapacitor with NCO5-rGO(1.5) as the positive electrode and rGO as a negative electrode using 1 M Na2SO4, neutral aqueous solution, as the electrolyte. The assembled supercapacitor delivered the specific capacitance value of 131 F g(-1) (197 C g(-1)) at an energy density of 47 W h kg(-1) and a power density of 631 W kg(-1) within a wide potential window of 1.6 V. The potential window of the device can be extended up to 2.4 V, but in that case, its coulombic efficiency decreases. The device retains a specific capacitance of 69% after 100 0 cycles of charge-discharge. Also, a solid-state device has been fabricated, which displays a potential of 3.4 V after charging 20 s. All these results may prove fruitful for the design of high energy density supercapacitors in the future. (c) 2021 Published by Elsevier Ltd.