Types Of Electrochemical Cells Research Articles

Synergistic production of graphene microsheets by simultaneous anodic and cathodic electro-exfoliation of graphitic electrodes in aprotic ionic liquids

Electrochemically mediated exfoliation of graphite is a promising green and high throughput approach for production of graphene sheets (GNs). Previous research focused mostly on either anode or cathode exfoliation due to restrictions imposed by the investigated intercalating ions and insufficient consideration given to the design of the electrochemical cell. Consequently, in single graphite electrode studies, at the non-graphitic counter-electrode (e.g. Pt), unwanted electrode reactions such as gas evolution and electrolyte decomposition take place, leading to significant energy and chemical losses. Here, we report the simultaneous anodic and cathodic GN production in two types of electrochemical cells (undivided and divided) using aprotic electrolytes containing ionic liquids (ILs). We demonstrate a synergistic exfoliation effect when the iso-molded graphite anode and cathode are subjected to a constant cell potential, generating up to 3times higher exfoliation yields compared to single-electrode studies on each side (∼6-fold improvement in total). Thorough characterization of the products collected from both electrode compartments confirmed the production of ultrathin GNs (<5 layers). The cathodic exfoliates were almost exclusively composed of GNs; whereas among the anodic products, in addition to the majority GNs, we detected traces of other morphologies such as nanoparticles, nanotubes, and larger rolled sheets.

Development of an electrochemical cell for in situ transmission electron microscopy observation.

A new type of electrochemical cell was developed for in situ transmission electron microscopy observation that enables the electrode materials to be conveniently changed. The electrochemical cell was used to observe the electrochemical growth or dissolution of copper islands on a gold film with simultaneous cyclic voltammetry measurements. The copper islands could be explained by three-dimensional growing model.

Microtubular solid-oxide fuel cells for low-temperature operation

Abstract

Production of formic acid from biomass-based compounds using a filter press type electrolyzer

There has been a growing interest for the sustainable production of formic acid (FA) in recent years considering its potential use as a hydrogen storage compound. In this context, the electrochemical transformation of carbohydrate-based biomass into formic acid in aqueous media was investigated using a filter-press type electrochemical cell. Therefore the oxidation of mono and disaccharides was carried out at NiOOH, RuO2/Ti (DSA) and PbO2 anodes, in FM01-LC (ICI) electrolyzer. The effect of carbon number of biomass compound, anode material and pH on product distribution was determined. Between the readily available carbohydrates studied in this work at NiOOH anode, in alkaline medium, d-xylose provides the highest selectivity towards formate anion, i.e. 42%. The transformation of d-glucose into formic acid, with 38% selectivity, was achieved at RuO2/Ti (DSA) in 0.5M NaOH medium, applying a current density of 80Am−2. The production of formate anion is mostly accompanied by the formation of oxalate anion and carbonates which constitute the by-products of the reaction. Considering that after acidification of carbonates the resulting CO2 can be easily removed and trapped by the growing plants which provide new biomass-based material, the transformation of oxalate anion (OA) into CO32− is of major importance. For this reason the oxidation of OA at DSA in 0.1M NaOH medium was also studied. In these conditions 60% of the initial oxalate anion was transformed to CO32− at 2.5V vs. SCE.

Elevated Rate Cycling of High-Power Electrochemical Energy Storage Devices for Use as the Prime Power Source of an EM Launcher

In recent years, energy storage manufacturers such as GAIA Advanced Lithium Battery Systems, Saft America, JM Energy, and Maxwell Corporation, among others, have greatly increased the power density of their respective electrochemical energy storage cells. Among the many types of high-power cells produced by the manufactures just listed are lithium-ion batteries, lithium-ion capacitors, and electric double-layer capacitors, respectively. The increased power density has made these types of portable energy storage devices more appealing and feasible for use as the prime power source of pulsed-power supplies that are used to drive systems such as electromagnetic launchers (EMLs). It has been previously shown by both Sitzman at the Institute for Advanced Technology, The University of Texas, Austin, and Allen and Neri at the U.S. Naval Research Laboratories that the prime power for small EMLs is derived from different types of batteries. In these types of pulsed-power systems, the batteries must be able to source pulsed currents at rates much higher than their continuous $C$ rating. While this mode of operation has been shown to be possible, the elevated rate limitations of these types of devices are not well published, and it is unclear how the fundamental aging phenomena that occur inside these types of devices will be affected. Researchers at the University of Texas, Arlington, have ongoing experiments which are testing the limitations of these types of electrochemical cells for use in pulsed high-current applications. Experiments are also being performed to understand the aging characteristics when they are operated at elevated rates that are tens to hundreds of their rated $C$ values. This paper describes the rationale behind the experiments, the experimental setup, and the research progress made thus far.

Influence of Graphite Characteristics on the Electrochemical Intercalation of Bis(trifluoromethanesulfonyl) imide Anions into a Graphite-Based Cathode

Electrochemical energy storage devices utilizing graphitic carbons as positive electrode material have been proposed as “dual-ion cells”. In this type of electrochemical cell, the electrolyte does not only act as a charge carrier, but additionally as the active material. In the charge process, lithium ions are inserted/intercalated or deposited into/on the negative electrode, e. g. Li4Ti5O12, graphite or metallic lithium, and the electrolyte anions are intercalated into the graphite positive electrode. In the discharge process, both lithium ions and anions are released back into the electrolyte. We report herein on the intercalation of bis(trifluoromethanesulfonyl) imide anions (TFSI−) into a graphite cathode from an ionic liquid-based, namely N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl) imide (Pyr14TFSI), electrolyte. We studied the influence of the graphite characteristics, such as the particle size distribution, specific surface area and ratio of basal plane to “non-basal plane” surface areas, on the electrochemical behavior of TFSI− anion intercalation. The rate performance, long-term cycling behavior and stability of dual-ion cells at high temperatures (60°C) are also discussed. A specific discharge capacity exceeding 100 mAh g−1 can be achieved at discharge rates of up to 10C, when operating at 60°C.

Salt bridges: fluid interactions between artists and scientists in the lab, Department of New Biochemistry, Oxford

A salt bridge in chemistry is a laboratory device used to connect the oxidation and reduction half-cells of a galvanic cell, a type of electrochemical cell. As electrons leave one...

Chemical compatibility of proton conducting LaNbO 4 electrolyte with potential oxide cathodes

The chemical and physical compatibility of the proton conducting electrolyte material LaNbO 4 with the potential partner materials LaMO 3 (M Mn, Fe, Co) and La 2NiO 4 is investigated via the reaction of fine-grained powders and solid-state diffusion couples. Results show generally good chemical compatibility for LaNbO 4 with perovskite type compositions, particularly the LaFeO 3 and LaMnO 3 systems. In contrast, Ruddlesden–Popper type phases are predicted to be poor candidates for use with LaNbO 4. Investigation of the La 2O 3–NiO–Nb 2O 5 and La 2O 3–CoO–Nb 2O 5 phase diagrams finds two new perovskite-related materials of stoichiometry LaNb 1/3M 2/3O 3 (M Ni, Co), and indicates coexistence of LaNbO 4 with the binary oxides NiO and CoO. Additionally, reduction of a LaNbO 4–NiO composite confirms coexistence of LaNbO 4 with Ni, and so it is concluded that doped-LaMO 3|LaNbO 4|Ni-LaNbO 4 type electrochemical cells may be manufactured via a direct co-firing route without the formation of secondary phases at inter-phase boundaries.

Metabolic studies of tetrazepam based on electrochemical simulation in comparison to in vivo and in vitro methods

During the last 2 years, the knowledge on the metabolic pathway of tetrazepam, a muscle relaxant drug, was expanded by the fact that diazepam was identified as a degradation product of tetrazepam. The present study demonstrates that this metabolic conversion, recently discovered by in vivo studies, can also be predicted on the basis of a purely instrumental method, consisting of an electrochemical cell (EC) coupled to online liquid chromatography (LC) and mass spectrometry (MS). By implementing a new electrochemical cell type into the EC-LC–MS set-up and by an enhanced oxidation potential range up to 2 V, one limitation of the electrochemical metabolism simulation, the hydroxylation of alkanes and alkenes, has been overcome. Instead of commonly used flow-through cell with a porous glassy carbon working electrode, a wall-jet cell with exchangeable electrode material was used for this study. Thereby, the entire metabolic pathway of tetrazepam, in particular including the hydroxylation of the tetrazepam cyclohexenyl moiety, was simulated. The electrochemical results were not only compared to microsomal incubations, but also to in vivo experiments, by analysing urine samples from a patient after tetrazepam delivery. For structure elucidation of the detected metabolites, MS/MS experiments were performed. The comparison of electrochemistry to in vitro as well as to in vivo experiments underlines the high potential of electrochemistry as a fast screening tool in the prediction of metabolic transformations in drug development.

Effect of Configuration on Mass Transfer in a Filter-press Type Electrochemical Cell

Effect of configuration (structure of electrode, interelectrode gap, positions of inlet and outlet, volume of the cell and additional nets) on mass transfer characteristic of a filter-press type electrochemical cell has been studied. The mass transfer coefficients on the electrodes were obtained by using the well-known technique based on the determination of limiting diffusion current. It is found that mass transfer coefficients with mesh electrode are greater than that of with plate electrode. Mass transfer coefficient is decreased with interelectrode gap. While interelectrode gap achieved a certain value (7 mm), mass transfer coefficient is steady, no more declining. Mass transfer characteristic for different positions of inlet and outlet are different and dimensionless number groups correlated equations are obtained by experiment. Mass transfer characteristic is the best when inlet located on the top and outlet on the bottom of the cell respectively. While magnified the volume of the cell to eight times, mass transfer characteristic changes little. Mass transfer characteristic without nets is lower than that of with additional nets in the exit region, but higher than that of with additional nets in the entry region.

Mediated electrochemical oxidation process: Electro-oxidation of cerium(III) to cerium(IV) in nitric acid medium and a study on phenol degradation by cerium(IV) oxidant

Cerium(III) in nitric acid medium was oxidized electrochemically using a flow type electrochemical cell fabricated in our laboratory. The variation of applied cell current, temperature and the concentration of the electrolyte were studied to determine the oxidation efficiency of Ce(III) in the electrochemical cell. The conversion yield of cerium(IV) in nitric acid was 97% in a short duration of 90 min. A bench scale degradation of phenol has been carried out by mediated electrochemical oxidation process using this oxidised Ce(IV) species. The influence of the concentration of phenol, temperature, amount of cerium, and the concentration of the electrolyte were studied on phenol destruction in a batch type reactor. It was found that nearly 70% of phenol was found to be destructed within 10 min. A good degradation yield was obtained above 70 °C. The effects of concentrations of cerium and nitric acid on phenol degradation were found to be moderate within the range investigated. The course of the reaction was followed by TOC analysis, estimating the CO2 evolved, and also measuring the potential of the Ce(IV)/Ce(III) redox couple.

No-carrier-added nucleophilic 18F-labelling in an electrochemical cell exemplified by the routine production of [ 18F]altanserin

A new type of electrochemical cell with anodic deposition of no-carrier-added [ 18F]fluoride and variable reaction volume has been developed. The reactor is designed for small reaction volumes and non-thermal drying of [ 18F]fluoride. The implementation of this reactor into a complete remotely controlled synthesis device is described for the routine production of [ 18F]altanserin. A radiochemical yield of 23±5% was obtained via cryptate-mediated nucleophilic 18F-fluorination. Batches of up to 6 GBq [ 18F]altanserin, suitable for human application, with a molar activity of >500 GBq/μmol were obtained within 75 min.

The application of cathodic reductions and anodic oxidations in the synthesis of complex molecules

This tutorial review surveys the recent advances in electrochemical transformations as they pertain to the synthesis of complex organic molecules. Electrochemistry has emerged as a powerful tool to synthetic chemists, yet many have never considered electrochemical methodology as a means for synthesis. Here, an introduction to electrochemistry and voltammetry will be provided with descriptions of the four types of electrochemical cells. In addition, recent examples of both anodic oxidations and cathodic reductions will be discussed, along with the experimental setups for carrying out each reaction.

Polarization Characteristics of Composite Electrodes in Electrochemical Cells with Solid Electrolytes Based on CeO2 and LaGaO3

For two types of electrochemical cells with oxygen-conducting solid electrolytes based on lanthanum gallate (LSGM) and cerium oxide (SDC) studied are the temperature dependences of the polarization conductivity of air electrodes prepared from lanthanum-strontium manganite (LSM) and composites LSM-LSGM, LSM-SDC, and LSM-SSZ (SSZ is zirconium dioxide-based electrolyte). Effect of praseodymium oxide, added into these electrodes as a modifier, on their electrochemical properties is examined. Electrochemical systems with an LSM/LSGM interface exhibit low electrochemical activity toward the oxygen reaction, because during the formation of electrodes, LSM interacts with LSGM to form a poorly conducting product.

Fabrication of a miniaturized cell using microsystem technologies for electrochemical applications

A new type of electrochemical cell has been developed for use in electrochemical, chemical and biological applications. Using a platinum microelectrode as working electrode, this cell incorporates a silver microelectrode as reference electrode. These microelectrodes, whose area is equal to 1 μm 2, were fabricated using photolithography, sputtering, and focused ion beam (FIB) technologies since these micro-fabrication techniques allow us to develop miniaturized electrochemical cells useful either for nanoelectrochemistry or biosensors applications. In this study, we show it is possible to coat a surface by chemical or biological compounds by immersing the microelectrodes in a solution, then setting a difference of potential between the two microelectrodes of the cell. For example, we used this miniaturized cell to realize the electrochemical polymerization of aniline into polyaniline to show that this electrochemical cell is efficient to coat a surface with a thin film of polymer.

Development of an electrochemical cell for efficient hydrogen production through the IS process

AbstractThe Bunsen reaction (SO2 + I2 + 2H2O = H2SO4 + 2HI) was examined by an electrochemical cell featuring a cation‐exchange membrane as the separator, using sulfuric acid dissolving sulfur dioxide as the anolyte and hydriodic acid dissolving iodine as the catholyte. In galvanostatic electrolysis, the molality of H2SO4 in the anolyte and that of HI in the catholyte were increased up to 17.8 and 14.9 mol kgH2O−1, respectively. These concentrations were far higher than those that were obtained by the Bunsen reaction carried out in the presence of a large amount of iodine (such as I2/HI = 4). I2 concentration after the concentration procedure was at I2/HI = 0.95, which is lower than the reported value. I2 is one of the recycling agents in the IS process. HI and H2SO4 were successfully concentrated under low I2 concentration. The concentration of HI agreed with the calculated value, based on the amount of electricity consumed, indicating high current efficiency. Heat/mass balance using this type of electrochemical cell through the IS process is discussed for evaluation of the reactor. The thermal efficiency to produce hydrogen was calculated at 42.1%, without heat recovery for electricity, by optimizing HI and H2SO4 concentrations after application of the electrochemical cell. © 2004 American Institute of Chemical Engineers AIChE J, 50: 1991–1998, 2004

Optimization of a Composite Working Electrode for a New Family of Electrochemical Cell for NO Decomposition

The electrochemical properties of a composite (NiO)x−(yttria‐stabilized zirconia (YSZ))1–x working electrode for a new type of electrochemical cell for NO decomposition in the presence of excess oxygen are investigated. It is shown that the dependence of the NO conversion on the value of the current passed through the electrochemical cell with a nanoporous (NiO)x−(YSZ)1–x working electrode is linear and that the value of current efficiency depends on the NO and O2 gas concentrations only (η= [NO] /([NO] + 2[O2]). The optimum NiO addition (35% by volume) to the YSZ resulted in a decrease of the cell operating voltage and, as a result, in a decrease in the electrical power required for NO decomposition. The observed high performance of the composite working electrode at this composition is consistent with the effective medium percolation theory, which predicts the ambipolar transport behavior of the composite mixed ionic−electronic (YSZ–NiO) conductors as a function of the volume fraction of each of the randomly distributed constituent phases.

Thermodynamics of { zNaCl+(1− z)Na 2SO 4}(aq) from T=278.15 K to T=318.15 K, and representation with an extended ion-interaction (Pitzer) model

In 1968, R.F. Platford reported the results from extensive isopiestic vapor-pressure measurements for the { zNaCl+(1− z)Na 2SO 4}(aq) system at T=298.15 K, using NaCl(aq) as the isopiestic reference standard [R.F. Platford, J. Chem. Eng. Data 13 (1968) 46–48]. However, only derived quantities were reported, and the experimental isopiestic equilibrium molalities were not given. The complete set of original isopiestic molalities from that study is tabulated in the present report. In addition, published thermodynamic information for this system is reviewed and the isopiestic equilibrium molalities, electromotive force measurements for five different types of electrochemical cells, and enthalpies of mixing from these other studies are critically assessed and recalculated consistently. These combined results are used to evaluate at T=298.15 K the two mixing parameters of Pitzer’s ion-interaction model, S θ( Cl, SO 4)=(1.236±0.032 5)·10 −2 kg· mol −1 and ψ( Na, Cl, SO 4)=(1.808±0.086)·10 −3 kg 2· mol −2 , and their temperature derivatives { ∂ S θ( Cl, SO 4)/ ∂T} p =(2.474±0.460)·10 −5 kg· mol −1· K −1 and { ∂ψ( Na, Cl, SO 4)/ ∂T} p =−(6.228±0.186)·10 −5 kg 2· mol −2· K −1 . Also reported are parameters for an extended ion-interaction model for Na 2SO 4(aq), valid from T=(273.15 to 323.15) K, that were required for this mixed electrolyte solution analysis.

Mathematical simulation of a vertically moving particle bed electrochemical cell

The cascade variant of the vertically moving particle bed (VMPB) cell represents a novel type of electrochemical cell for technological and wastewater treatment using a rotating three-dimensional electrode. It is characterized by a high surface area, high space–time yield and simple handling. These properties have been achieved by electrode rotation, a cascade arrangement of single rotating drums and automatic particle exchange between neighbouring rotating drums. Two types of mathematical model have been developed. They differ with regard to the degree of complexity and the numerical mathematics method used to solve the equations derived. The results obtained by the two types of model are compared. The influence of the main process parameters is studied for the model case of a single drum cell. The viability of the individual model types for evaluating the influence of the operation parameters of the cell on its performance is discussed.

Electrochemical treatment and reuse of nickel plating rinse waters

AbstractThe treatment and disposal of nickel‐contaminated rinse waters places an additional cost‐burden on a metal plating facility. Increasing the resource productivity within an electrolytic nickel plating process by creating a recycle loop for the “waste” components of the rinse water can reduce disposal and raw material costs. In this study, an electrowinning cell, fitted with an anion exchange membrane, was used to recover valuable components from a simulated electrolytic nickel plating rinse water by a combination of electrodeposition and electrodialysis. The anion exchange membrane in the cell permitted a dual electrode function. Nickel metal was recovered from the rinse water at the cathode and a sulfuric/hydrochloric acid mixture was generated at the anode (which can be used in the pickling baths to clean metal parts). The boric acid in the rinse water could not be recovered by anion exchange due to its high acid dissociation constant. The cell worked effectively in both a batch and a continuous feed mode. The research demonstrated that this type of electrochemical cell could feasibly replace the traditional ion exchange process for treating rinse waters, and eliminate regeneration chemicals/waste while producing useful process materials.