Increase In Electrode Area Research Articles

Electrochemical impedance spectroscopy of AB3 active electrode in nickel metal hydride accumulators: The effect of temperatures and immersion times

The electrochemical impedance spectroscopy (EIS) method was employed systematically to investigate the kinetic properties of the LaY2Ni9 electrode, which serves as negative electrode in Ni-MH accumulators. Through this analysis, a comprehensive understanding of the electrode’s behaviour was achieved.EIS measurements were performed on the LaY2Ni9 electrode at different temperatures (ranging from 15 °C to 75 °C) and at different immersion times using a potentiostat and frequency response analyser.The EIS spectra were fitted using an equivalent circuit model to extract the electrode impedance parameters, such as the charge transfer resistance, Rtc, the absorption/double layer capacities, Cad and Cdl, the specific current density, I0,EIS, and the hydrogen penetration depth, δ. The results show that temperatures have significant effects on the EIS impedance of the LaY2Ni9 electrode. The Rtc and the Cdl parameters increase with temperature, indicating a decrease in electrode kinetics due to the higher activation energy and an increase in electrode area due to thermal expansion. The penetration depth, δ, is directly proportional to the temperature increase.According to the EIS results, it is generally considered advantageous to maintain an operating temperature of around 30 °C for the LaY2Ni9 electrode. Moreover, a correlation can be observed between the variations in the kinetic parameter (DH) and the corresponding changes in other electrochemical parameters.Inconsistencies arise when comparing the exchange current density values obtained through cyclic voltammetry (I0,CV) and impedance spectroscopy (I0,EIS), highlighting contradictory findings. These disparities can be ascribed to multiple factors, including temperature variations, electrode geometry, and concentration gradients near the electrode interface. Overall, this study provides valuable information on the performance and degradation mechanisms of the LaY2Ni9 electrode under temperature and immersion time conditions and highlights the importance of EIS impedance measurements for battery research and development.

Effects of parameters selection with transcranial direct current stimulation based on real head model

Transcranial direct current stimulation (tDCS) is a brain stimulation intervention technique, which has the problem of different criteria for the selection of stimulation parameters. In this study, a four-layer real head model was constructed. Based on this model, the changes of the electric field distribution in the brain with the current intensity, electrode shape, electrode area and electrode spacing were analyzed by using finite element simulation technology, and then the optimal scheme of electrical stimulation parameters was discussed. The results showed that the effective stimulation region decreased and the focusing ability increased with the increase of current intensity. The normal current density of the quadrilateral electrode was obviously larger than that of the circular electrode, which indicated that the quadrilateral electrode was more conducive to current stimulation of neurons. Moreover, the effective stimulation region of the quadrilateral electrode was more concentrated and the focusing ability was stronger. The focusing ability decreased with the increase of electrode area. Specifically, the focusing tended to increase first and then decrease with the increase of electrode spacing and the optimal electrode spacing was 64.0-67.2 mm. These results could provide some basis for the selection of electrical stimulation parameters.

Application of Ti/RuO 2–Ta 2O 5 electrodes in the electrooxidation of ethanol and derivants: Reactivity versus electrocatalytic efficiency

The influence of the preparation method on the performance of RuO 2–Ta 2O 5 electrodes was evaluated toward the ethanol oxidation reaction (EOR). Freshly prepared RuO 2–Ta 2O 5 thin films containing between 30 and 80 at.% Ru were prepared by two different methods: the modified Pechini–Adams method (DPP) and standard thermal decomposition (STD). Electrochemical investigation of the electrode containing RuO 2–Ta 2O 5 thin films was conducted as a function of electrode composition in a 0.5-mol dm −3 H 2SO 4 solution, in the presence and absence of ethanol and its derivants (acetaldehyde and acetic acid). At a low ethanol concentration (5 mmol dm −3), ethanol oxidation leads to high yields of acetic acid and CO 2. On the other hand, an increase in ethanol concentration (15–1000 mmol dm −3) favors acetaldehyde formation, so acetic acid and CO 2 production is hindered, in this case. Electrodes prepared by DPP provide higher current efficiency than STD electrodes for all the investigated ethanol concentrations. This may be explained by the increase in electrode area obtained with the DPP preparation method compared with STD.

Voltammetric response of epinephrine at carbon nanotube modified glassy carbon electrode and activated glassy carbon electrode

The electrochemical behavior of epinephrine at activated glassy carbon electrode and carbon nanotube-coated glassy carbon electrode was studied. Epinephrine could exhibit an anodic peak at about 0.2 V (vs. SCE) at bare glassy carbon electrode, but it was very small. However, when the electrode was activated at certain potential (i. e. 1.9 V) or modified with carbon nanotube, the peak became more sensitive, resulting from the increase in electrode area in addition to the electrostatic attraction. Under the selected conditions, the anodic peak current was linear to epinephrine concentration in the range of 3.3×10−7–1.1×10−5 mol/L at activated glassy carbon electrode and in the range of 1.0×10−6–5.0×10−5 mol/L at carbon nanotube-coated electrode. The correlation coefficients were 0.998 and 0.997, respectively. The determination limit was 1.0×10−7 mol/L. The two electrodes have been successfully applied for the determination of epinephrine in adrenaline hydrochloride injection with recovery of 95%–104%.

Electrocatalysis and related factors of platinum microparticles dispersed on/in polypyrrole film in methanol oxidation

Platinum microparticles display effective electrocatalysis for methanol oxidation in 1 M MeOH+1 M HClO4 and polypyrrole film exhibits a promotive action for such electrocatalysis. The electrocatalytic activity is determined by the loading mass of the platinum microparticles, and the potential and medium used for the electropolymerization of PPy film. The thickness of the polypyrrole film under the chosen experimental conditions is less critical towards the electrocatalysis of MeOH oxidation. The effect of the increase in electrode area due to the high dispersion of platinum microparticles is substantially deducted in the evaluation of the catalytic activity because the real surface of the platinum microparticles, rather than the projected area of the electrode, is used in the calculation of the current density.

Effect of area on surface flashover voltage in vacuum

It is known that the breakdown voltage in a vacuum insulation system drops with an increase in linear dimension of electrodes and with an increase in the number of insulating spacers bridging the gap. Normally this is explained to be the result of the increase in the number of so-called weak links in the system. The influence of an external capacitance on the flashover voltage of an electrode gap bridged by a spacer was investigated. When a capacitor was connected inside the vacuum chamber near the discharge site in parallel with the gap, it was found that the additional capacitance lowered the breakdown voltage in a manner similar to that observed with an increase in electrode area. This supports the energy explanation of the area effect. A larger external capacitor, far from the discharge site, had no influence on the breakdown voltage.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Kinetics of the Solid Lithium Electrode in Propylene Carbonate

Kinetic parameters for solid lithium electrodes have been evaluated at for in propylene carbonate at several concentrations between 0.1 and 1.0M. Polarization data obtained by the interrupted current method agree with that obtained by a pulse technique. Depending on its treatment, the electrode exhibits one of two levels of activity. This phenomenon is believed to be due to the presence of a film formed by reaction between lithium metal and the solvent or impurities. The film is broken down at higher current densities, effecting an increase in electrode area. The area increase has been corroborated by double‐layer capacitance measurements. Standard exchange current of a film‐free electrode in is .