Nickel-Hydroxide-Nanohexagon-Based High-Performance Electrodes for Supercapacitors: A Systematic Investigation on the Influence of Six Different Carbon Nanostructures

Abstract

Transition-metal compounds (TMCs) such as oxides, hydroxides, and sulfides are well-known pseudocapacitive materials whose capacitance has been shown to improve by combining them with different carbon nanostructures (CNSs). Here, we report a systematic investigation on the influence of six different CNSs: single-walled carbon nanotubes (SWCNTs), functionalized and multiwalled carbon nanotubes, graphene oxide (GO), reduced GO (rGO), and graphene nanoplatelets on Ni­(OH)2 nanostructures, focusing on their electrochemical properties for potential use as electrode materials in supercapacitors. Uniformly distributed Ni­(OH)2 nanohexagons (approximately 30–35 nm in size) were found to be well attached to the surfaces of these CNSs. Among the studied CNSs, rGO appeared to be the best as its composite with Ni­(OH)2 exhibited the highest specific capacitance of 2306 F/g at 3 A/g along with 81.4% capacity retention after 5000 cycles. The SWCNT/Ni­(OH)2 composite showed the second best performance, with all other composites showing much lower performances. The lower charge transfer resistance and higher ion diffusion coefficient of the rGO/Ni­(OH)2 composite, compared to those of all other composites of Ni­(OH)2, have been identified as the reason for its improved performance. These results may find far-fetching significance in designing TMC-nanostructure-based electrodes modified with CNSs for supercapacitors.

Influence of La3+induced defects on MnO2–carbon nanotube hybrid electrodes for supercapacitors

“…It can be observed that the CV curve for 2La-MnO 2 -CNThas the largest enclosed area and thus is expected to exhibit the highest specific capacitance. values were obtained at high scan rates [26,37]. However, at low scan rates due to the increase in interaction time, the electrolyte ions gets a chance to enter into the pores of the active electrode material due to prolonged exposure.…”

Electrochemical Properties of Iron Oxide Decorated Activated Carbon Cloth as a Binder-Free Flexible Electrode

“…Porous carbon materials such as activated carbon 6 , CNT 7 , graphene oxide (GO) 8 , reduced GO (rGO) 9 , xerogel-like 10 , and aerogels 11 are largely applied for supercapacitor electrodes because of properties like high surface area, chemical stability, high conductivity, and stable electrochemical properties 1,2,12 . Activated carbon fibers are attractive materials for supercapacitor electrodes or other applications 13 , especially because of their flexible structure and three-dimensional arrangement comprising a continuous current path, decreasing the interparticle resistance 2,14 and increasing the surface area simultaneously.…”

“…The equivalent series resistance (ESR) and charge transfer resistance (R ct ) were estimated from the total equivalent circuit using the curve fitting of the electrochemical impedance spectroscopy (EIS) plot. All the samples present a semicircle in the high-frequency region associated with the charge transfer at the interface between the electrode and the electrolyte 8 . Additionally, the vertical shape of electrodes produced at 140 and 170 minutes at a low-frequency range is attributed to the EDLC characteristic of the ions diffusion process on porous structure 56 .…”

“…These differences could be related to structural variations of the electrodes that affect the conductivities of the assembly 7 . Furthermore, the R ct value of ACC140_Fe is the smallest, followed by ACC170_Fe and ACC110_Fe, respectively, and thus the ACC140_Fe electrode is expected to present faster ions transfer with a higher diffusion coefficient value (Table 4) estimated from CV using the Randles Sevcik equation 8,57 . A larger ion diffusion coefficient allows easy transport of ions into the electrode material.…”

CeO2/Ce2O3 quantum dot decorated reduced graphene oxide nanohybrid as electrode for supercapacitor

“…to form nanohybrids. [26][27][28][29][30][31][32][33] A relatively less studied metal oxide is ceria (CeO 2 ) in spite of its dynamic redox reaction, ecofriendly features and low cost. A major drawback of CeO 2 is its poor electrical conductivity [34] that can be tuned by changing its shape and size using controlled synthetic conditions by playing with the growth parameters.…”