Interelectrode Resistance Research Articles

Synthesis and characterization of LAGP-glass-ceramics-based composite solid polymer electrolyte for solid-state Li-ion battery application

Solid State Electrolytes (SSEs) are the future alternatives of the present conventional liquid electrolytes in terms of safety, high temperature stability and also good electrochemical performance. Glass (G), based on Lithium Aluminium Germanium Phosphate (LAGP) was prepared and converted into glass-ceramics (GC) by optimized heating schedule. The crystalline LAGP has Na Super Ionic CONductor (NASICON) type unit cell where the lithium ions hop between two different positions providing long range ionic motion. To improve the inter-electrode surface resistance and cell performance, Composite Solid Electrolyte (CSE) was prepared with poly(vinylidene fluoride-co-hexaflurophoaphate) (P(VDF-HFP)), 20wt% LAGP, Lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and 1-Ethyl-3-methylimidazolium bis-(trifluoromethylsulfonyl)-imide (EMITFSI). X-ray diffraction patterns confirm the formation of the NASICON phase in LAGP GC and the amorphous nature of the CSE. NMR studies confirm formation of the Ge/AlO6 octahedra and PO4 tetrahedra inside the crystal. 7Li NMR also confirmed two different Lithium sites in LAGP crystal. The ionic conductivity values of CSE and LAGP GC are (4.49±0.31) × 10−3Scm−1 and (2.70±0.04) × 10−4Scm−1, respectively. The thermal stability of the prepared CSE is tested upto 315°C without any degradation. Two cells (Cell-I & Cell-II) were fabricated using the LAGP GC and CSE respectively. Cell-II shows the specific discharge capacity of 151mAhg−1 at 50th cycle which is higher as compared to Cell-I (129mAhg−1) when tested at the C-rate of 0.05C.

Computational Modelling of Electrical Conduction in Ferroalloy Furnace Burdens

A computational model of the electrical behaviour of the burden layer in a ferroalloy furnace system is presented, focusing on ferrochromium as an example case. The model is based on the discrete element method, which calculates the mechanical interactions and resulting motion of each particle in large ensembles. A simplified set of relationships describing the melting and reaction zones around each electrode tip is included in the computational model to control the continuous consumption of particles, and it is shown how different consumption mechanisms for different types of particles can lead to the formation of reductant-rich beds and other geometric structures within the burden. A method for calculating the inter-electrode electrical resistance by constructing a network based on particle contacts is developed and used to generate quantitative estimates of inter-electrode burden conduction effects under different conditions of electrode geometry and particle consumption dynamics.

Электрохимическая очистка грунтов с различной концентрацией нефтяных загрязнений при использовании единого источника электрического напряжения

The most essential scientifific and practical task in the area of ecological safety of pipelines operation is the development and improvement of methods of purifification and restoration of oil-contaminated soils. One of the most effificient and cost effective methods is electrochemical purifification, that does not require the use of expensive chemical reagents and soil excavation. However, the consideration of non-uniform contamination of various soil sections is required. The article examines the features of the organization and technological infrastructure for electrochemical purifification of non-uniformly contaminated soils when using a single electrical energy source, a method for calculating the design parameters of the corresponding installation is proposed. Effificient purifification of non-uniformly contaminated soil when using a specifified voltage is possible through the use of different-sized electrodes. For each soil type, the amount of transmitted electric charge required for soil purifification is determined by the concentration of the contaminant. Allocation of cathodes and anodes as parallel batteries and their connection using individual buses is an effective and energy-effificient solution, since an almost-uniform electric fifield is created in an inter-electrode space, thus allowing the reduction of the interelectrode resistance of the medium.

THE HUMIDITY AND STRUCTURING ADDITIVES INFLUENCE ON ELECTROPHYSICAL CHARACTERISTICS OF TIN DIOXIDE FILMS

The structuring additive concentration and humidity influence on the electrophysical properties of tin dioxide films was studied. The growth of SnO2 films, interelectrode resistance with the growth of polyvinyl acetate concentration in the initial solution is due to the porosity increase caused by the PVA increase in the films under study. The section of dark current temperature dependence, in vacuum from 110 °C with an activation energy ~ 0.7 eV, is due to the water molecules desorption. The resistance decrease of tin dioxide films in a wet atmosphere due to the dissociative adsorption of water molecules on the SnO2 layers surfaces has been established.

Diagnosis and treatment of simple forms of chronic tonsillitis in patients with laryngopharyngeal reflux

Nowadays, 4 cochlear implant systems are certified in the Russian Federation. One of the objective indicators for the cochlear implant functioning is the interelectrode resistance (impedance). The impedance directly affects the power consumption of the processor battery, making it possible to estimate the functional adequacy of the implant. The objective of this study is to survey different cochlear implant systems electrode resistance. To solve this problem, 80 patients (children under 5) with different types of cochlear implant systems (20 types per each one) participated in the study for 24 months. All the children were operated on and adjusted according to the routine clinical practice. During connection of the speech processor and the next 3, 6, 9, 12, 18 and 24 months impedance was measured at each individual electrode. During the cochlear implants operation, after speech processor connection, continuous electric pulse stimulation of the implants, resulting in the change of the impedance, can be observed. Monitoring of electrode resistance, carried out during the 2 researches revealed the implant with the most unstable and highest impedance, resulting, in some cases, in the change of stimulation strategy; besides the implant with the lowest impedance was revealed.

Research on Cathode Chronopotentiograms and Interelectrode Resistance during Vacuum Boiling Electroforming

Studies have showed that the electrolyte vacuum boiling electroforming process can significantly improve surface quality and microstructures of the deposited layer. To explore the mechanisms that produce the above-mentioned favorable improvements, this paper focused on analyzing the change characteristics of cathode potential and interelectrode resistance carried out under different process conditions. Research results showed that, reducing vacuum degree or increasing cathode surface temperature result in an intense fluctuation in the cathode chronopotentiometry and interelectrode resistance; decreasing the vacuum degree causes the whole cathode chronopotentiometry to shift negatively, but situation is opposite when the cathode surface temperature rises.

Inter-electrode tissue resistance is not affected by tissue oedema when electrically stimulating the lower limb of sepsis patients

ICU patients typically are given large amounts of fluid and often develop oedema. The purpose of this study was to evaluate whether the oedema would change inter-electrode resistance and, thus, require a different approach to using non-invasive electrical stimulation of nerves to assess muscle force. Inter-electrode tissue resistance in the lower leg was measured by applying a 300 µs constant current pulse and measuring the current through and voltage across the stimulating electrodes. The protocol was administered to nine ICU patients with oedema, eight surgical patients without oedema and eight healthy controls. No significant difference in inter-electrode resistance was found between the three groups. For all groups, resistance decreased as stimulation current increased. In conclusion, inter-electrode resistance in ICU patients with severe oedema is the same as the resistance in regular surgical patients and healthy controls. This means that non-invasive nerve stimulation devices do not need to be designed to accommodate different resistances when used with oedema patients; however, surface stimulation does require higher current levels with oedema patients because of the increased distance between the skin surface and the targeted nerve or muscle.

Determination of the minimum alveolar concentration of isoflurane in Shetland ponies using constant current or constant voltage electrical stimulation

ObjectiveTo determine the minimum alveolar concentration (MAC) of isoflurane in Shetland ponies using a sequence of three different supramaximal noxious stimulations at each tested concentration of isoflurane rather than a single stimulation. Study designProspective, experimental trial. AnimalsSeven 4-year-old, gelding Shetland ponies. MethodsThe MAC of isoflurane was determined for each pony. Three different modes of electrical stimulation were applied consecutively (2 minute intervals): two using constant voltage (90 V) on the gingiva via needle- (CVneedle) or surface-electrodes (CVsurface) and one using constant current (CC; 40 mA) via surface electrodes applied to the skin over the digital nerve. The ability to clearly interpret the responses as positive, the latency of the evoked responses and the inter-electrode resistance were recorded for each stimulus. ResultsIndividual isoflurane MAC (%) values ranged from 0.60 to 1.17 with a mean (±SD) of 0.97 (±0.17). The responses were more clearly interpreted with CC, but did not reach statistical significance. The CVsurface mode produced responses with a longer delay. The CVneedle mode was accompanied by variable inter-electrode resistances resulting in uncontrolled stimulus intensity. At 0.9 MAC, the third stimulation induced more positive responses than the first stimulation, independent of the mode of stimulation used. ConclusionsThe MAC of isoflurane in the Shetland ponies was lower than expected with considerable variability among individuals. Constant current surface electrode stimulations were the most repeatable. A summation over the sequence of three supramaximal stimulations was observed around 0.9 MAC. Clinical relevanceThe possibility that Shetland ponies require less isoflurane than horses needs further investigation. Constant current surface-electrode stimulations were the most repeatable. Repetitive supramaximal stimuli may have evoked movements at isoflurane concentrations that provide immobility when single supramaximal stimulation was applied.

The influence of amplifier, interface and biological noise on signal quality in high-resolution EEG recordings

First, the intrinsic random noise sources of a biopotential measurement in general are reviewed. For the special case of an electroencephalographic (EEG) measurement we have extended the commonly used amplifier noise model by biological generated background noise. As the strongest of all noise sources involved will dominate the resulting signal to noise ratio (S/N), we have investigated under which conditions this will be the case. We illustrate experimentally that up to 100 Hz S/N practically depends only on cortical generated background noise, while at a few hundred Hz or more amplifier and thermal noise of interelectrode resistance are the major sources.

Manufacturing and characterization of a modified four-quadrant position sensitive detector for out-door applications

Position sensing detectors (PSDs) are useful in many applications such as vibration, displacement and triangulation measurements. In this paper we have constructed a novel structure, which has higher inter-electrode resistance than a lateral effect PSD and is more robust to atmospheric turbulence than a conventional four-quadrant PSD (Nuclear Instruments and Methods in Physics Research A 466 (2001) 183). The detector structure is useful for applications with detector windows less than 0.5×0.5mm2, but the nonlinearity is the main concern for a detector of that size. Without any corrections for non-linearity the standard deviation of the error is 9μm (2.2%). Using a simple analytical expression and a 2-d correction-function stored in a look-up table the positioning error is reduced to 6 (1.5%) and 2 (0.5%)μm, respectively.

Ohmic interelectrode voltage drop in alumina reduction cells

The large gas bubbles underneath the anode in Hall–Heroult cells not only affect the ohmic interelectrode resistance by decreasing the cross-sectional area available for current transport. They also exhibit a strong effect on the current distribution in the bubble-free layer, substantially increasing the resistance. Available relationships applied in aluminium industry do not take this effect into account. A review on attempts to describe the interelectrode resistance is given, and an improved relationship derived from a finite element model is presented.

Simulation of a low atmospheric-noise modified four-quadrant position sensitive detector

A modified four-quadrant position sensitive detector (PSD) is developed. This structure is less sensitive to atmospheric turbulence that is a major drawback with the traditional four-quadrant detector. The inter-electrode resistance is as high as for the four-quadrant detector, which is an advantage compared to the lateral effect PSD. The linearity for the modified four-quadrant detector is good in the whole active range of sensing. The structures are limited to small sensing areas with well focused beams and are suitable for use in detectors up to 1 mm in size.

Spatial potential and current distributions along transvenous defibrillation electrodes: variation of electrode characteristics.

The therapeutic efficacy of an endocardial defibrillation lead system can be improved by controlling the profile of current delivery through a suitable choice of electrode characteristics, which include the length, radius, number of conductor elements, electrode resistance, and point of connection to the voltage source. Such control will minimize tissue and lead damage during long-term use. In this study, a semianalytical model was developed to study cylindrical electrodes of different constructions in an idealized electrolytic medium. Simulations were performed to investigate the effects of varying the electrode characteristics on the spatial voltage and current distributions and interelectrode resistance for cylindrical electrodes of different constructions. The results show that, for transvenous electrodes of realistic dimensions, the current distributions are determined largely by the edge effects. The edge effects increase as the aspect ratio of the electrode (length/radius) decrease. The multiple edges resulting from wrapping conductor elements over a nonconducting base are found to increase the nonuniformity and the current density over the conductor-covered surface. The model is used to demonstrate two techniques of controlling the current distribution. The first method involve modifying the electrode resistivity profile and point of connection. In the second approach, the electrode surface is covered with a thin film having a model-computed resistance profile. By using either methods to produce isocurrent electrodes, the interelectrode resistance is found to increase.

Physical modeling studies of electrolyte flow due to gas evolution and some aspects of bubble behavior in advanced hall cells: Part I. Flow in cells with a flat anode

The need for energy reduction in the electrolytic production of aluminum led to the concept of advanced Hall cells that can be operated at lower interelectrode gaps compared to existing cells. However, gas bubbles generated by the anodic reaction increase the resistivity of electrolyte and cancel out part of the reduction in interelectrode resistance expected from bringing the electrodes closer together. Therefore, the primary objective of this work was to determine a cell design in which flow can be managed to promote the removal of anode gas bubbles from the interelectrode gap. In particular, this article focuses on advanced Hall cells equipped with “flat” anodes, similar to those used in existing cells. The principal experimental tool has been a “water” model consisting of a large tank in which simulated anodes can be suspended in either the horizontal or near-horizontal configurations. Gas was generated by forcing compressed air through porous graphite, and the fine bubbles characteristic of inert anodes used in advanced Hall cells were produced by adding butanol to water. Velocities were measured using a laser-Doppler velocimeter (LDV). This study indicates that the existing cell configuration might not be the optimum configuration for advanced Hall cells. The results also show that operation of an advanced Hall cell with a fully submerged anode should give rise to higher electrolyte velocities and thus rapid removal of bubbles. The bubble effect should be further lowered in a near-horizontal configuration; however, the flow pattern could have an adverse effect on current efficiency and alumina distribution in the cell. It has also been shown that the bubble size, and, therefore, the physical properties of the electrolyte, can have a significant effect on the electrolyte flow pattern in the interelectrode gap.

Effects of skin temperature on skin-electrode impedance: measurements at high direct current density.

Skin-electrode impedance was determined between two disposable electrodes 5 cm apart on the volar skin of the forearm in 20 patients during cooling on cardiopulmonary bypass. Measurements were made using a constant direct current pulse of 200 microseconds duration, at a current density of 25.6 mA cm-2. The mean inter-electrode resistance was 1.11 k omega, and the mean inter-electrode capacitance was 33.3 nF. In 19 patients there was no change in the inter-electrode resistance or the inter-electrode capacitance with changes in skin temperature from 27.5 to 36.0 degrees C. In one patient the inter-electrode resistance increased from 1.71 k omega at 35 degrees C to 1.94 k omega at 31.0 degrees C, while the inter-electrode capacitance increased from 19.6 to 26.6 nF. We conclude that temperature effects on the impedance of the stimulus electrodes are not responsible for the observed failure of evoked electromyography during clinical monitoring of neuromuscular function.

Accurate modeling of interelectrode resistance and power dissipation in electric glass melters

An accurate technique for modeling the interelectrode resistances as well as the potential and power density distributions in electric glass melters is presented. The model also provides necessary data for sizing the supply transformers associated with such melters. The solution technique involves only algebraic equations, and therefore can be implemented by simple computer software. An example melter with a two-phase supply and eight electrodes was simulated using the proposed three-dimensional modeling technique. Because of the general nature of the proposed model, this technique provides a valuable as well as reliable and easily implemented design tool for melters with multiphase power supplies and general electrode configurations. >

The voidage problem in gas-electrolyte dispersions

Assessing the ohmic interelectrode resistance of electrochemical reactors with gas evolution requires data for the gas void fraction of gas-electrolyte dispersions. A voidage equation is derived taking account of the internal liquid flow in stationary electrolytes and at small liquid superficial velocities. The equation is a general form of available voidage equations.

Laser-drilled multichannel multidepth extracellular microelectrodes.

The paper describes the construction and characteristics of a new multichannel, multidepth microelectrode designed for extracellular biopotential recording. The electrode is constructed from a group of six borosilicate glass capillary tubes which are hot drawn to form 40–50 μm tubes. A CO2 laser of 400 kW cm−2 peak power is used to cut side holes in the drawn tubes of 30–40 μm diameter and at intervals of 200 μm in respective tubes, thus creating six electrodes at six different depths. When filled with 9·9M NaCl solution typical electrode resistance is 300 kΩ and the interelectrode resistance 800 kΩ.

Effect of operational parameters on gas evolution in electrolyte bulk: possibilities for lowering interelectrode resistance

Two facts form the basis of the present investigation. Firstly: generally, only a fraction of the total quantity of dissolved gas generated at a gas-evolving electrode is evolved in gaseous form directly at the electrode. Secondly: commonly, only a fraction of the complementary amount of dissolved gas reaching the bulk of electrolyte is evolved in the interelectrode gap. This paper analyses the conditions in which a major portion of the total amount of dissolved gas generated at the electrode remains in dissolved form when being withdrawn from the interelectrode gap. Increasing this amount results in lowering the effective resistivity of the gas—electrolyte dispersion.

Systematic errors in conductimetric instrumentation due to bubble adhesions on the electrodes: An experimental assessment

Systematic errors in conductimetric measurements are often encountered due to partial screening of interelectrode current paths resulting from adhesion of bubbles on the electrode surfaces of the cell. A method of assessing this error quantitatively by a simulated electrolytic tank technique is proposed here. The experimental setup simulates the bubble-curtain effect in the electrolytic tank by means of a pair of electrodes partially covered by a monolayer of small polystyrene-foam spheres representing the bubble adhesions. By varying the number of spheres stuck on the electrode surface, the fractional area covered by the bubbles is controlled; and by measuring the interelectrode impedance, the systematic error is determined as a function of the fractional area covered by the simulated bubbles. A theoretical model which depicts the interelectrode resistance and, hence, the systematic error caused by bubble adhesions is calculated by considering the random dispersal of bubbles on the electrodes. Relevant computed results are compared with the measured impedance data obtained from the electrolytic tank experiment. Results due to other models are also presented and discussed. A time-domain measurement on the simulated cell to study the capacitive effects of the bubble curtain is also explained.