Zinc cobalt sulfide nanoparticles as high performance electrode material for asymmetric supercapacitor

Abstract

Zinc cobalt sulfide (ZCS) is a promising and high performance electrode material for pseudocapacitors due to its good electrical conductivity, abundant active sites and rich valence states. In this work, zinc cobalt oxide (ZCO) nanoparticles are firstly synthesized via a hydrothermal method assisted by hexadecyltrimethyl ammonium bromide (CTAB), and then transformed into zinc cobalt sulfide nanoparticles (ZCS NPs) using a facile sulfuration process. The average diameter of ZCS NPs is estimated to be about 15 nm, which is beneficial for Faradaic redox reactions in energy storage process due to their numerous active surfaces. The ZCS NPs are then coated onto a nickel foam to form the working electrode of supercapacitors. Because the ZCS electrode has lower series and charge transfer resistance, and also higher ion diffusion rate than that of the ZCO electrode, it achieves a large specific capacitance of 1269.1 F g -1 at 0.5 A g -1 in 2 M KOH electrolyte, which is four times more than that of the ZCO electrode (e.g., 295.8 F g -1 at 0.5 A g -1 ). In addition, an asymmetric supercapacitor using the ZCS NPs as the positive electrode and activated carbon as the negative electrode is assembled, which delivers a high energy density of 45.4 Wh kg -1 at a power density of 805.0 W kg -1 , with an excellent cycling stability (91.6 % retention of the initial capacitance over 5000 cycles).

Room-temperature synthesized porous Cu(OH)2/Cu7S4 hybrid nanowires as a high-performance electrode material for asymmetric supercapacitors

“…The shapes of CV and GCD curves can be well kept with the increased voltage. Therefore, this ASC device can perfectly work at a wide voltage window of 1.7 V without apparent oxygen evolution53 . Moreover, all the GCD curves are almost symmetrical, indicating that the ASC exhibits good capacitive properties.…”

“…This further proves the battery-type characteristic of Cu(OH)2/Cu7S4 hybrid nanowires. The specific capacity of C (C g -1 ) can be calculated according to the GCD curves based on the following formula53 : mA), Δt (s), and m (mg) are the discharge current, discharge time, voltage window and mass of the electrode material, respectively. Due to the unique architecture of porous hybrid nanowires, the Cu(OH)2/Cu7S4 electrode has a very large specific capacity of 1610.8 C g -1 at the discharge current density of 4 A g -1 .…”

Cu-MOF derived Cu–C nanocomposites towards high performance electrochemical supercapacitors

“…Due to the diversity of organic ligands, MOFs are characterized by strong chemical modication and adjustable size, which achieves extensive potential applications in uorescence, sensing, gas adsorption and separation, catalysis and other elds. [29][30][31][32][33][34][35][36][37][38][39] In recent years, materials prepared by calcining MOFs as templates or precursors under different conditions, such as MOF based multiporous carbon materials, metal oxides and their complexes, have shown excellent performance in lithium ion batteries, supercapacitors and other elds. [40][41][42][43][44][45] Based on the above considerations, herein, the Cu-C nanocomposites derived from Cu-MOFs is prepared and fully characterized, where the copper nanoparticles are evenly dispersed in porous carbons.…”

Mesoporous Zr-doped CeO2 nanostructures as superior supercapacitor electrode with significantly enhanced specific capacity and excellent cycling stability

“…6f, revealing a good rate capacity of the CeO2-Zr-1//AC ASC device. The energy density (E, Wh kg −1 ) and power density (P, W kg −1 ) can be calculated based on the GCD curves according to the following eqations [64,65]: based ASCs reported in the literature as illustrated in the Fig. 7a, the energy and power densities of CeO2-Zr-1//AC device in this study are much higher, e.g., better than those of CeO2 nanorods (5.1 Wh/kg at 250 W/kg) [66], CeO2/CeS2 (21.2 Wh/kg at 303 W/kg) [57] and CeO2 nanoparticles (12.68 Wh/kg at 100 W/kg) [27].…”