Ferrous Nitrate–Nickel Oxide (Fe(NO3)2–NiO) Nanospheres Incorporated With Carbon Black and Polyvinylidenefluoride for Supercapacitor Applications

2019 ◽  
Vol 16 (3) ◽  
Author(s):  
Aqib Muzaffar ◽  
Keerthana Muthusamy ◽  
M. Basheer Ahamed
Keyword(s):  
Nickel Oxide ◽  
Specific Capacitance ◽  
Double Layer ◽  
Electrochemical Impedance ◽  
Maximum Efficiency ◽  
Potential Range ◽  
Double Layer Capacitance ◽  
Hydrothermal Route ◽  
Sem Images ◽  
Charge Discharge

Ferrous nitrate/nickel oxide {Fe(NO3)2–NiO} nanocomposite was synthesized via two-step facile hydrothermal route. The nanocomposite exhibits crystalline structure as unveiled by X-ray diffraction (XRD) pattern, while as the scanning electron microscope (SEM) images divulge spherical morphologies for both Fe(NO3)2 as well as NiO nanoparticles differentiating from each other in size. Cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), and electrochemical impedance spectroscopy (EIS) techniques were used to investigate supercapacitive behavior of the symmetrically fabricated nanocomposite electrode configuration using aqueous KOH as the electrolyte. The CV analyses demonstrate dominant electrical double layer capacitance (EDLC) behavior in the potential range of 0–1 V. From charge–discharge curves, the maximum specific capacitance calculated was 460 F g−1 corresponding to the energy density of 16 W h kg−1 at a high power density of 250 W kg−1. EIS data affiliate well with the CV and GCD results justifying the maximum contribution of specific capacitance due to double layer capacitance. The nanocomposite retained 84% of its original capacitance after 1000 cycles and yielded maximum efficiency of 78%.

scholarly journals Lithium-Rich Cobalt-Free Manganese-Based Layered Cathode Materials for Li-Ion Batteries: Suppressing the Voltage Fading

Energies ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 3487
Author(s):  
Ashraf Abdel-Ghany ◽  
Ahmed M. Hashem ◽  
Alain Mauger ◽  
Christian M. Julien
Keyword(s):  
Layered Structure ◽  
Performance Enhancement ◽  
Electrochemical Impedance ◽  
Discharge Process ◽  
High Porosity ◽  
Li Ion Batteries ◽  
Hydrothermal Route ◽  
Li Ion ◽  
Fading Rate ◽  
Charge Discharge

Lithium-rich layered oxides are recognized as promising materials for Li-ion batteries, owing to higher capacity than the currently available commercialized cathode, for their lower cost. However, their voltage decay and cycling instability during the charge/discharge process are problems that need to be solved before their practical application can be envisioned. These problems are mainly associated with a phase transition of the surface layer from the layered structure to the spinel structure. In this paper, we report the AlF3-coating of the Li-rich Co-free layered Li1.2Ni0.2Mn0.6O2 (LLNMO) oxide as an effective strategy to solve these problems. The samples were synthesized via the hydrothermal route that insures a very good crystallization in the layered structure, probed by XRD, energy-dispersive X-ray (EDX) spectroscopy, and Raman spectroscopy. The hydrothermally synthesized samples before and after AlF3 coating are well crystallized in the layered structure with particle sizes of about 180 nm (crystallites of ~65 nm), with high porosity (pore size 5 nm) determined by Brunauer–Emmett–Teller (BET) specific surface area method. Subsequent improvements in discharge capacity are obtained with a ~5-nm thick coating layer. AlF3-coated Li1.2Ni0.2Mn0.6O2 delivers a capacity of 248 mAh g−1 stable over the 100 cycles, and it exhibits a voltage fading rate of 1.40 mV per cycle. According to the analysis from galvanostatic charge-discharge and electrochemical impedance spectroscopy, the electrochemical performance enhancement is discussed and compared with literature data. Post-mortem analysis confirms that the AlF3 coating is a very efficient surface modification to improve the stability of the layered phase of the Li-rich material, at the origin of the significant improvement of the electrochemical properties.

scholarly journals Electrochemical Characteristics of Particulate Matter

2011 ◽  
Vol 7 (-1) ◽  
pp. 19-26 ◽  
Author(s):  
Margarita Baitimirova ◽  
Agnese Osite ◽  
Juris Katkevich ◽  
Arturs Viksna
Keyword(s):  
Particulate Matter ◽  
Double Layer ◽  
Mass Concentration ◽  
Electrochemical Impedance ◽  
Cyclic Voltammograms ◽  
Electrochemical Characteristics ◽  
Impedance Spectra ◽  
Double Layer Capacitance ◽  
Spectra Analysis ◽  
Aerosol Mass Concentration

Electrochemical Characteristics of Particulate Matter The current work is dedicated to electrochemical impedance spectra analysis of the fine and coarse airborne particulate matter sampled on the glass fibre filters in Riga city air. The cyclic voltammograms, impedance spectra and double layer capacitance spectra of particulate matter were obtained after the pre-treatment of samples. The equivalent circuit method and the statistical method were used for impedance spectra analysis. Analyzing the impedance spectra, it was concluded that the impedance of both - fine and coarse particles heated in N2 flow does not change by aerosol mass concentration variations. On the other hand, the impedance of particulate matter heated in O2 flow increases, by increasing PM10 mass concentration. Describing the spectra of double layer capacitance, it was observed that the double layer capacitance of aerosols heated in N2 flow did not change, by mass concentration and size variations. However, by increasing mass concentration of coarse aerosols heated in O2 flow, the double layer capacitance reduced.

Nitric Acid Activated Carbon Aerogels for Supercapacitors

2013 ◽  
Vol 302 ◽  
pp. 158-164 ◽  
Author(s):  
Ya Jie Li ◽  
Xing Yuan Ni ◽  
Jun Shen ◽  
Dong Liu ◽  
Nian Ping Liu
Keyword(s):  
Activated Carbon ◽  
Nitric Acid ◽  
Electrochemical Impedance ◽  
Carbon Aerogels ◽  
Electrochemical Performances ◽  
Galvanostatic Charge ◽  
Sem Images ◽  
Resorcinol Formaldehyde ◽  
Charge Discharge ◽  
Discharge Test

The electrochemical performances of resorcinol–formaldehyde-based carbon aerogels can be significantly enhanced by nitric acid activation.FT-IR spectra and SEM images reveal the constitution and morphology of samples .The electrochemical performances of materials were tested by cyclic voltammetry,galvanostatic charge/discharge test ,electrochemical impedance spectroscopy and cyclic test. The results show that activation does not influence the molecular structure of carbon aerogels,which maintains their nano-porous structure. Activation increases the specific capacitance by 50% and improves the conductivity of carbon aerogels,resulting in fenfect cycling stability. So nitric acid activated carbon aerogels is an ideal electrode material for supercapacitors.

scholarly journals Polarography of Te (IV) Anions in Neutral Solutions in Presence of 2,2'- Dipyridyl and Fe(dipy)3 2+ - Complexes

2016 ◽  
Vol 7 (1) ◽  
pp. 41
Author(s):  
M.B. Dergacheva ◽  
V.N. Statsyuk ◽  
L.A. Fogel
Keyword(s):  
Double Layer ◽  
Layer Structure ◽  
Supporting Electrolyte ◽  
Mercury Electrode ◽  
Electrochemical Reactions ◽  
Potential Range ◽  
Double Layer Capacitance ◽  
Buffer Solutions ◽  
Double Layer Structure ◽  
Mercury Electrodes

<p>The electroreduction of Te (IV) ions in neutral non-buffer solutions containing 2,2'-dipyridyl (4⋅10<sup>-5</sup>- 4⋅10<sup>-3</sup> M) or tris-dipyridyl iron (II) complexes is studied by the polarographic method. NaF (0.01-0.5 M) or NaNO<sub>3</sub> (0.1-1 M) are used as supporting electrolytes. The mechanism of electrochemical reactions of Te (IV) anions on mercury electrodes in the presence of the additives is discussed. The electroreduction of Te (IV) anions is shown to proceed through electron transfer and proton addition. The obtained results point to a considerable influence of electric double layer structure on electrochemical reactions of Te (IV) ions in the presence of inorganic and specifically adsorbed organic compounds in the electrolyte. It is shown, that 2,2'-dipyridyl does not form complexes with Te (IV) anions. Having been adsorbed on the surface of mercury electrode, 2,2'-dipyridyl complexes increase negative <em>Ψ</em>'-potential that results in a shift of Te (IV) electroreduction wave to more negative potentials and decrease in the current of Te (IV) wave and peak at -1.19 V. It is shown that 2,2'-dipyridyl molecules at <em>ε</em> &gt; 0, (<em>ε</em> – charge of an electrode) are adsorbed in plane orientation, and at ε &lt; 0, plane or vertical. Vertically adsorbed molecules cause a significant decrease in the double layer capacitance. At negative potentials orientation of 2,2'-dipyridyl molecules changes from plane to vertical with the increasing 2,2'-dipyridyl concentration. This change of orientation results in a typical maximum capacitance emerging in the potential range of -0.7 to -1.2 V. It is shown that the supporting electrolyte, 2,2'-dipyridyl and Fe(dipy)<sub>3</sub> <sup>2+</sup>  have influence on the electroreduction of Te (IV) anions in neutral non-buffer solutions through a change in the <em>Ψ</em>'-potential of mercury electrode.</p>

Effects of Deposition Temperatures on the Nanoflakes Co(OH)2 Porous Films for Supercapacitors

2011 ◽  
Vol 694 ◽  
pp. 214-218
Author(s):  
Zhan Jun Yu ◽  
Bin Bin Wang ◽  
Rong Bao Liao ◽  
Yu Min Cui
Keyword(s):  
Specific Capacitance ◽  
Electrochemical Impedance ◽  
Electrochemical Techniques ◽  
High Specific Capacitance ◽  
Electrochemical Technique ◽  
Porous Films ◽  
Discharge Current Density ◽  
A Charge ◽  
Maximum Specific Capacitance ◽  
Charge Discharge

Nanoflakes Co(OH)2 porous films were successfully synthesized by a facile electrochemical technique. The morphology was characterized by field emission scanning electron microscopy (FESEM). Electrochemical techniques such as cyclic voltammetry (CV), galvanostaitc charge/discharge and electrochemical impedance spectroscopy were used to study the effects of deposition temperatures on the capacitance of the films. The results exhibited that the Co(OH)2 films single electrode had high specific capacitance in KOH electrolyte. A maximum specific capacitance of 2780 F/g could be achieved for the Co(OH)2 film deposited at 50°C in 2 M aqueous KOH with 0 to 0.4V potential at a charge-discharge current density of 4 mA/cm2. Therefore, the obtained nanoflakes Co(OH)2 porous films can be a potential application electrode material for supercapacitors.

Measurement of Aluminium Oxide-Film Thickness: Barrier Oxide Film and Oxide Porous Layer

2008 ◽  
Vol 273-276 ◽  
pp. 283-293 ◽  
Author(s):  
Khaled Habib ◽  
K. Al-Muhanna ◽  
F. Al-Sabti ◽  
A. Al-Arbeed
Keyword(s):  
Aqueous Solution ◽  
Oxide Film ◽  
Film Thickness ◽  
Sulphuric Acid ◽  
Double Layer ◽  
Holographic Interferometry ◽  
Electrochemical Impedance ◽  
Double Layer Capacitance ◽  
Oxide Film Thickness

In the present investigation, holographic interferometry was utilized for the first time to measure in situ the thickness of the oxide film, alternating current (A.C.) impedance, and double layer capacitance of aluminium samples during anodization processes in aqueous solution without any physical contact. The anodization process (oxidation) of the aluminium samples was carried out by the electrochemical impedance spectroscopy (EIS), in different concentrations of sulphuric acid (0.5-2.5 % H2SO4) at room temperature. In the mean time, the real-time holographic interferometric was used to measure the thickness of anodized (oxide) film of the aluminium samples in aqueous solutions. Also, mathematical models were applied to measure the alternating current (A.C.) impedance, and double layer capacitance of aluminium samples by holographic interferometry, during anodization processes in aqueous solution. Consequently, holographic interferometric is found very useful for surface finish industries especially for monitoring the early stage of anodization processes of metals, in which the thickness of the anodized film, the A.C. impedance, and the double layer capacitance of the aluminium samples in sulphuric acid (0.5-2.5 % H2SO4) can be determined in situ. Futhermore, a comparison was made between the electrochemical values obtained from the holographic interferometry measurements and from measurements of electrochemical impedance spectroscopy(EIS) on aluminium samples in sulphuric acid (0.5-2.5 % H2SO4). The comparison indicates that there is good agreement between the obtained electrochemical data from both techniques. However, there is a drastic difference between the measurement of the oxide film thickness by both techniques. The oxide film thickness of the aluminium samples in 0, 0.5, 1.0, 1.5, 2.0, 2.5% H2SO4 by the optical interferometry is in a micrometer scale. However, the oxide film thickness of the aluminium samples in 0, 0.5, 1.0, 1.5, 2.0, 2.5% H2SO4 by the E.I.Spectroscopy in a nanometer scale. This can be explained due to the fact that the E.I.Spectroscopy is useful technique to measure the electrochemical parameters and the thickness of the barrier (compact) oxide films. In contrast, the optical interferometry is found useful technique to characterize and measure the thickness of the porous oxide layer. Also, the optimum thickness of the oxide barrier film was detected to be equivalent to 0.612nm in sulphuric acid concentration of 2.5% H2SO4 by E.I. spectroscopy.

Hydrothermal synthesis of PANI nanowires for high-performance supercapacitor

2019 ◽  
Vol 32 (3) ◽  
pp. 258-267 ◽  
Author(s):  
Jia Chu ◽  
Xue Li ◽  
Qiaoqin Li ◽  
Jing Ma ◽  
Bohua Wu ◽  
...  
Keyword(s):  
Specific Capacitance ◽  
Current Density ◽  
Photoelectron Spectroscopy ◽  
High Performance ◽  
Electrochemical Impedance ◽  
Scanning Electron Micrographs ◽  
X Ray ◽  
Different Temperatures ◽  
Polyaniline Nanowires ◽  
Charge Discharge

Polyaniline nanowires (PANI NWs) were synthesized under different temperatures through a facile hydrothermal method and used as electrodes for high-performance pseudocapacitor. The resulting samples were analyzed by X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy, scanning electron micrographs, thermogravimetric analysis, and X-ray photoelectron spectroscopy. Electrochemical properties of these PANI electrodes are studied by cyclic voltammetry, galvanostatic charge–discharge test, and electrochemical impedance spectroscopy in 0.5M H2SO4 aqueous solution. The highest specific capacitance is obtained on the PANI NWs synthesized under 80°C (PANI-80) with 540.0 F g−1 at current density of 0.5 A g−1 accompanied with 82% specific capacitance retention after 1000 charge discharge cycles at 5 A g−1 current density.

Fluorine-Doped Graphene/Nanosized Carbide-Derived Carbon Composites for High-Performance Supercapacitor

NANO ◽  
2019 ◽  
Vol 14 (08) ◽  
pp. 1950099 ◽  
Author(s):  
Pengtao Yan ◽  
Lei Yan ◽  
Sumei Zhao ◽  
Zhen Zuo ◽  
Xiaoxu Wang ◽  
...  
Keyword(s):  
Specific Capacitance ◽  
Double Layer ◽  
Electric Double Layer ◽  
High Performance ◽  
High Specific Surface Area ◽  
Double Layer Capacitance ◽  
Doped Graphene ◽  
Hierarchical Pore ◽  
Carbide Derived Carbon ◽  
Electric Double Layer Capacitance

A graphene-based composite with high electrochemical performance for supercapacitor applications is fabricated by introducing nanoscale carbide-derived carbon (NCDC) into the fluorine-doped graphene (FG). The incorporation of fluorine can increase the specific capacitance of graphene by providing more pseudocapacitance, whereas the introduction of NCDC into the FG/NCDC composite offers high specific surface area (SSA) (up to 1317[Formula: see text]m2[Formula: see text]g[Formula: see text]) and hierarchical pore structure, resulting in an enhanced electric double layer capacitance. Due to the synergistic effect of pseudocapacitance and electric double layer capacitance, the specific capacitance of FG/NCDC composite can reach 321 F g[Formula: see text] at a scan rate of 5[Formula: see text]mV[Formula: see text]s[Formula: see text] in aqueous electrolyte. Notably, the specific capacitance of the FG/NCDC composite is very stable during long-term cyclic tests, with no significant degradation after 10,000 cycles. Due to its excellent supercapacitive performance, the FG/NCDC composite can be considered as a promising electrode material for high-performance supercapacitors.

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