An Asymmetrical Supercapacitor Based on CNTs/SnO2 and CNTs/MnO2 Nanocomposites Working at 1.7 V in Aqueous Electrolyte

Abstract

An asymmetrical supercapacitor was fabricated with a CNTs/SnO2 negative electrode and a CNTs/MnO2 positive electrode. It was tested in charge and discharge to 1.7 V in aqueous electrolyte without showing noticeable current resulting from water decomposition. Physicochemical properties of the CNTs/SnO2 and CNTs/MnO2 nanocomposites were examined by X-ray diffraction (XRD) and scanning electron microscopy (SEM), cyclic voltammetry (CV), galvanostatic charge/discharge and electrochemical impedance spectrometry (EIS). At a current density of 0.25A g-1, the energy density of the hybrid supercapacitor was found to be 20.3 Whkg-1 which is comparable to that obtained from electric double layer supercapacitors using organic electrolytes (17~18Wh kg-1). The asymmetrical supercapacitor also shows exceptional stability over 1000 cycles with the capacity loss being less than 8%.

Hydrothermal Growth of Hierarchical Ni3S2 and Co3S4 on a Reduced Graphene Oxide Hydrogel@Ni Foam: A High-Energy-Density Aqueous Asymmetric Supercapacitor

“…The increased power density did not result in a significant loss of energy density, and a high energy density of 24.84 Wh/kg was achieved at a very high power delivery rate of 13000 W/kg. The maximum specific energy density is much higher or somewhere comparable than some other reported related asymmetric supercapacitors, such as AC//Co­(OH) 2 (25.7 Wh/kg), CNT/Ni­(OH) 2 //AC (16.8 Wh/kg at 400 W/kg), AC//NiO (15–20 Wh/kg), CNTs/MnO 2 //CNTs/SnO 2 (20.3 Wh/kg), Ni­(OH) 2 //graphene (30 Wh/kg) . Ni­(OH) 2 /CNT-AC (32.5 Wh/kg at a power density of 1800 W/kg), AC//Ni 3 S 2 /CNT (19.8 Wh/kg), nickel–cobalt sulfide//AC (25 Wh/kg), NiCo 2 S 4 //RGO (31.5 Wh/kg), and CoS 2 //AC (37 Wh/kg) .…”

High-performance flexible asymmetric supercapacitors based on a new graphene foam/carbon nanotube hybrid film

“…These values are comparable with or better than those of previously reported ASCs. [72][73][74] Lightweight and exible supercapacitors that have excellent electrochemical performance even under mechanical deformation are highly desired to meet the demands of future development of multifunctional exible electronics. In order to explore the potential application of GF/CNT/MnO 2 -GF/CNT/Ppy ASCs as a exible power source, the ASC is placed with a mechanical bending angle and its electrochemical performance is evaluated by the corresponding CV curves (Fig.…”

α-Fe2O3-Based Core-Shell-Nanorod–Structured Positiveand Negative Electrodes for a High-Performance α-Fe2O3/C//α-Fe2O3/MnOxAsymmetric Supercapacitor

“…8 The energy density of supercapacitors can be enhanced by increasing their capacitance as well as their operating-potential window, which can be achieved more easily with asymmetric supercapacitors (ASCs) than with the symmetric supercapacitors (SSCs) since, with suitable combination of positive and negative electrode materials, the operational potential window as high as 2 V has been achieved even with aqueous electrolytes. 6,[9][10][11][12][13][14] In recent years, efforts have been expended to explore several ASCs with different electrode materials based on redox-active transition-metal oxides, like RuO 2 , 15 SnO 2 , 23 etc., which are not commercially viable owing to their high cost and environmental incompatibility. Accordingly, there is need to explore certain alternative combinations of positive and negative electrode materials to design a high-performance, cost-effective and environmentally benign ASC.…”

“…4,[6][7][8][9][10][11]13,14,19,23,24 Besides MnO 2 suffers from poor electri- * Electrochemical Society Fellow. z E-mail: deb.sarkar1985@gmail.com; akshukla2006@gmail.com; sarma@iisc.ac.in cal conductivity (10 −5 -10 −6 S/cm), which affects the rate capability of the supercapacitors, but this limitation could be circumvented through nanostructured core-shell electrode design.…”