Facile hydrothermal synthesis of flowerlike ZnCo 2 O 4 microspheres as binder-free electrodes for supercapacitors (original) (raw)
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Bulletin of Materials Science
Supercapacitors as energy storage devices have attracted great attention due to their high-specific capacitance, fast rechargeability, high-power density, performance, long cycle life and low-maintenance cost. These unique advantages enable their applications in portable electronic devices, gadgets, hybrid electric vehicles, etc. However, developing flexible, high performance, stable and economic storage devices is the need of time. With this motivation, binder-free ZnCo 2 O 4 thin films are synthesized on flexible stainless steel mesh by a hydrothermal method. The structural, morphological and physicochemical properties of ZnCo 2 O 4 are investigated using X-ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy (FESEM) and energy dispersive spectroscopy. FESEM images reveal thin films with flower-shaped microspheres composed of bunched nanowires providing a large surface area (72 m 2 g −1) which is confirmed by Brunauer-Emmett-Teller analysis. The electrochemical performance of the ZnCo 2 O 4 thin film electrode exhibited a specific capacitance of 127.8 F g −1 at a current density of 1 mA cm −2. It also shows good rate capability and excellent electrochemical cycling stability (80.66% specific capacitance retention after 3000 cycles).
Molecules
Scientific research is being compelled to develop highly efficient and cost-effective energy-storing devices such as supercapacitors (SCs). The practical use of SC devices is hindered by their low energy density and poor rate capability due to the binding agents in fabricating electrodes. Herein, we proposed flower-like highly open-structured binder-free ZnCo2O4 micro-flowers composed of nanosheets supported in nickel foam (ZnCoO@NF) with improved rate capability up to 91.8% when current varied from 2 to 20 A·g−1. The ZnCoO@NF electrode exhibited a superior specific capacitance of 1132 F·g−1 at 2 A·g−1 and revealed 99% cycling stability after 7000 cycles at a high current density of 20 A·g−1. The improved performance of the ZnCoO@NF electrode is attributed to the highly stable structure of the micro/nano-multiscale architecture, which provides both the high conduction of electrons and fast ionic transportation paths simultaneously.
Ionics, 2017
ZnCo 2 O 4 nanoflakes were directly grown on Ni foam via a two-step facile strategy, involving cathodic electrolytic electrodeposition (ELD) method and followed by a thermal annealing treatment step. The results of physical characterizations exhibit that the mesoporous ZnCo 2 O 4 nanoflakes have large electroactive surface areas (138.8 m 2 g −1) and acceptable physical stability with the Ni foam, providing fast electron and ion transport sites. The ZnCo 2 O 4 nanoflakes on Ni foam were directly used as integrated electrodes for supercapacitors and their electrochemical properties were measured in 2 M KOH aqueous solution. The ZnCo 2 O 4 nanoflake electrode exhibits a high capacitance of 1781.7 F g −1 at a current density of 5 A g −1 and good rate capability (62% capacity retention at 50 A g −1). Also, an excellent cycling ability at various current densities from 5 to 50 A g −1 was obtained and 92% of the initial capacitance maintained after 4000 cycles. The results demonstrate that the proposed synthesis route is cost-effective and facile and can be developed for preparation of electrode materials in other electrochemical supercapacitors.
Hydrothermal synthesis of Mn-doped ZnCo 2 O 4 electrode material for high-performance supercapacitor
Mn-doped ZnCo 2 O 4 nanoparticle has been synthesized by hydrothermal method without adding any surfactants. Structural, morphological and electrochemical performances have been studied for the pure and various concentration of Mn-doped ZnCo 2 O 4 nanoparticles. XRD and Raman studies demonstrate the crystalline structure of the material. Specific capacitance of the 10 wt% Mn doped ZnCo 2 O 4 nanomaterial is analysed using the three-electrode system. 10 wt% Mn-doped ZnCo 2 O 4 has a maximum capacitance of 707.4 F g −1 at a current density of 0.5 A g −1. Coulombic efficiency of the material is 96.3% for 500 cycles in the KOH electrolyte medium. A two-electrode device using 10 wt% Mn-doped ZnCo 2 O 4 exhibits the highest specific capacitance of 6.5 F g −1 at a current density of 0.03 A g −1 which is the suitable material for supercapacitor application.
Aqueous asymmetric supercapacitors based on ZnCo 2 O 4 nanoparticles via facile combustion method
ZnCo 2 O 4 (ZCO) nanoparticles are synthesized via a facile, fast and cost-effective combustion method. The effect of calcination temperature is studied on the morphology, crystallite size and electrochemical properties of the ZCO. Scanning electron microscope observation reveals that the calcination temperature strongly influences the morphology of the prepared ZCO. At the calcination temperatures of 300, 400 and 600 C, the ZCO samples show the specific capacitance values of 202, 668 and 843 F g À1 , respectively with the current density of 1 A g À1. Furthermore, higher calcination temperature (800 C) leads to rapid increment of particle size, low specific capacitance (432 F g À1 at 1 A g À1) and inferior rate capability of ZCO, which may be related to the severe micro-strain and crack formation upon repeated electrolytic ions during charging-discharging process. Owing to the excellent specific capacitance of the ZCO (prepared at 600 C), its performance is further investigated in asymmetric supercapacitor (ASC) device and a high energy density of 26.28 W h kg À1 is obtained at the power density of 716 W kg À1 under the current density of 1 A g À1. Parallel-connected 14 light-emitting diodes are lit up from seriesconnected two ASCs. In addition, a motor fan is powered by the two ASCs. In the light of the above results, the ZCO nanoparticles may be expected to be a prospective viable electrode material for highperformance supercapacitors.
Nanomaterials, 2020
The demand for eco-friendly renewable energy resources as energy storage and management devices is increased due to their high-power density and fast charge/discharge capacity. Recently, supercapacitors have fascinated due to their fast charge–discharge capability and high-power density along with safety. Herein, the authors present the synthesis of 3D-hierarchical peony-like ZnCo2O4 structures with 2D-nanoflakes by a hydrothermal method using polyvinylpyrrolidone. The reaction time was modified to obtain two samples (ZCO-6h and ZCO-12h) and the rest of the synthesis conditions were the same. The synthesized structures were systematically studied through various techniques: their crystalline characteristics were studied through XRD analysis, their morphologies were inspected through SEM and TEM, and the elemental distribution and oxidation states were studied by X-ray photoelectron spectroscopy (XPS). ZCO-12h sample has a larger surface area (55.40 m2·g−1) and pore size (24.69 nm) t...
Potato Chip-Like 0D Interconnected ZnCo2O4 Nanoparticles for High-Performance Supercapacitors
Crystals, 2021
Zinc cobaltite (ZnCo2O4) is an emerging electrode material for supercapacitors due to its rich redox reactions involving multiple oxidation states and different ions. In the present work, potato chip-like 0D interconnected ZnCo2O4 nanoparticles (PIZCON) were prepared using a solvothermal approach. The prepared material was characterized using various analytical methods, including X-ray powder diffraction and scanning electron microscopy. The possible formation mechanism of PIZCON was proposed. The PIZCON electrode material was systematically characterized for supercapacitor application. The areal capacitance of PIZCON was 14.52 mF cm−2 at 10 µA cm−2 of current density, and retention of initial capacitance was 95% at 250 µA cm−2 following 3000 continuous charge/discharge cycles. The attained measures of electrochemical performance indicate that PIZCON is an excellent supercapacitor electrode material.
Unique ZnMn2O4@ZnFe2O4 microspheres were fabricated on Ni foam using a facile and cost-effective hydrothermal method for high-performance supercapacitor applications. The resulting ZnMn2O4@ZnFe2O4 electrode was characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and electrochemical techniques. The ZnMn2O4@ZnFe2O4 electrode exhibited a microsphere-like morphology with a mean size of B50–115 nm. The electrochemical performance of the ZnMn2O4@ZnFe2O4 electrode was investigated and the results showed that the ZnMn2O4@ZnFe2O4 electrode exhibits a high specific capacitance of 1024.66 F g1 at 10 mA cm2, low internal resistance, and remarkable cycling stability with 95.8% capacitance retention after 3000 charge–discharge cycles, which was superior to those of the ZnMn2O4 and ZnFe2O4 electrodes. Such enhanced electrochemical performance and the facile synthetic method of ZnMn2O4@ZnFe2O4 electrode materials offer great promise in next generation supercapacitor applications.
The Bulletin Tabbin Institute for Metallurgical Studies (TIMS)
The target for developing electrode materials with unique architecture and tailored composition is essential for influencing their electrochemical properties. The innovative porous zinc cobalt sulfide (ZnCo2S4/ Ni foam (NF)) nanocoral reef-like structure supported by 3D NF is fabricated by the hydrothermal method. Here is an advanced electrode for supercapacitors (SCs), which demonstrates the notable electrochemical performance of the electrode in terms of the specific capacity of 2055.2 C g-1 (specific capacitance of 1957.4 F g-1) at 1 A g-1 and excellent cyclic stability of 89.2% capacity retention and 98% coulombic efficiency after 5000 cycles. Furthermore, the battery-type symmetric supercapacitors based on ZCS/NF have an ultrahigh energy density of 39.1 Wh kg-1 at a power density of 1637 W kg-1 with excellent cyclic stability, 93.3% capacity retention, and 100% coulombic efficiency after 6000 cycles. The outstanding characteristics can be attributed to the synergistic contribution of the ZnCo2S4/NF coral reef hierarchical architecture and the bimetallic sulfide with great valence states for rich redox reactions. Therefore, the nano coral reef ZnCo2S4/NF is promising electrode material for battery-type supercapacitors.