• Sharma, Yogesh
• Kumar, Amit
• Leu, Jim
• Tseng, Tseung-Yuen
• Kumar, Nagesh

Abstract

<p>Herein, we report a novel, simple, and cost-effective way to synthesize flexible and conductive rGO and rGO/MWCNT freestanding films. The effects of MWCNT addition on the electrochemical performance of rGO/MWCNT nanocomposite films are investigated in some strong base aqueous electrolytes, such as KOH, LiOH, and NaOH via three-electrode system. The supercapacitor behavior of the films is probed via cyclic voltammetry, galvanostatic charging-discharging, and electrochemical impedance spectroscopy. The structural and morphological studies of the films are performed by X-ray diffractometer, Raman spectrometer, surface area analyzer, thermogravimetric analysis, field emission scanning electron microscope and transmission electron microscope. The rGO/MWCNT film synthesized with 10 wt% MWCNTs (GP10C) exhibits high specific capacitance of 200 Fg⁻¹, excellent cyclic stability with 92% retention after 15,000 long cycle test, small relaxation time constant (~ 194 ms), and high diffusion coefficient (7.8457 × 10⁻⁹ cm² s⁻¹) in 2 M KOH electrolyte. Furthermore, the symmetric supercapacitor coin cell with GP10C as both anode and cathode using 2 M KOH as electrolyte demonstrates high energy density of 29.4 Whkg⁻¹ and power density of 439 Wkg⁻¹ at current density 0.1 Ag⁻¹ and good cyclic stability with 85% retention of the initial capacitance at 0.3 Ag⁻¹ after 10,000 cycles. Such a high performance of the GP10C film in the supercapacitor can be ascribed to the large surface area and small hydration sphere radius and high ionic conductivity of K⁺ cations in KOH electrolyte.</p>

Topics

• nanocomposite
• density
• impedance spectroscopy
• surface
• energy density
• mass spectrometry
• thermogravimetry
• current density
• cyclic voltammetry