Showing papers on "Anode published in 1979"
TL;DR: In this article, the authors discuss the interaction between battery requirements, in particular for vehicle propulsion, and electrochemical and constructional factors, and show that the energy obtainable at a given load is limited by saturation of the surface layers of cathode particles with cations, and that the time before saturation is determined by diffusion of cations and electrons into the host lattice.
Abstract: Battery systems based on alkali metal anodes and solid solution cathodes,i.e., cathodes based on the insertion of the alkali cation in a "host lattice," show considerable promise for high energy density storage batteries. This paper discusses the interaction between battery requirements, in particular for vehicle propulsion, and electrochemical and constructional factors. It is argued that the energy obtainable at a given load is limited by saturation of the surface layers of cathode particles with cations, and that the time before saturation occurs is determined by diffusion of cations and electrons into the host lattice. Expressions are developed for plane, cylindrical, and spherical particles, giving the relation between battery load and the amount of cathode material utilized before saturation. The particle shape and a single parameter is used to describe cathode performance. is the ratio between discharge time at 100% utilization of the cathode at the given load, and the time constant for diffusion through the cathode particles. This description is extended to cover short peak loads characteristic of vehicle propulsion. On the basis of estimated parameters for the couple with electrolyte the properties of plane cathodes or cathodes consisting of few layers of particles are examined in relation to traction requirements. In this context limiting currents in the electrolyte phase are discussed, and a relation between the maximal allowed values for particle size and electrode spacing is derived. For nonporous electrodes the limiting factor is cathode surface saturation. A qualitative discussion of porous cathodes indicates that the cathode thickness, and thus the over‐all specific energy, is limited by cation transport in the pore electrolyte when the cation diffusion coefficient in the solid exceeds 10−10 cm2 sec−1. On the basis of an approximate relation between cathode thickness and electrode spacing the specific energy for the system with organic electrolyte is estimated to be 120–150 W‐hr/kg in agreement with published values.
229 citations
TL;DR: In this article, the reaction proceeds at very mild temperatures and at operating electrical potentials significantly lower than the thermodynamic potential of water electrolysis, and the observed activation energies and the expected decomposition temperatures of the presumed intermediates suggest that much more rapid and steadier oxidation rates might be achieved at higher temperatures in the range 200-600 °C.
Abstract: Coals and other forms of solid carbonaceous fossil fuel are oxidised to oxides of carbon at the anode of an electrochemical cell and hydrogen is produced at the cathode, these gases being produced in relatively pure states. The reaction proceeds at very mild temperatures and at operating electrical potentials significantly lower than the thermodynamic potential of water electrolysis. Although the reaction is readily observable at room temperature, the observed activation energies and the expected decomposition temperatures of the presumed intermediates suggest that much more rapid and steadier oxidation rates might be achieved at higher temperatures in the range 200–600 °C.
204 citations
TL;DR: In this paper, a scanning electron microscope study of the electrode structure helps to understand the deterioration of electrical properties which occurs when samples are subjected to high temperatures and/or current densities.
Abstract: Electrode polarization is studied by means of a current interruption method with the aid of a reference electrode. In this way anodic and cathodic overpotentials, η, can be measured separately, and the electrolyte polarization (IR drop) can be distinguished from the electrode overpotentials. Platinum paste electrodes are used with several doped ceria electrolytes in oxygen‐argon gas atmospheres. At high , the curves obey the Butler‐Volmer equation, with transfer coefficients of unity, both for anodic and cathodic polarizations. This result implies a charge‐transfer (or activation) mechanism. Study of the exchange current, , as a function of and temperature shows that oxygen for the charge‐transfer process is supplied through adsorbed adatoms on the Pt electrode surface, obeying the Langmuir isotherm. An activation energy of 1.75 eV is obtained for the charge‐transfer step. At low , limiting‐current behavior is obtained for the cathodic polarization, characteristic of a concentration polarization. A scanning electron microscope study of the electrode structure helps to understand the deterioration of electrical properties which occurs when samples are subjected to high temperatures and/or current densities.
189 citations
TL;DR: In this paper, the design and operating characteristics of relativistic, electron beam magnetrons are described, and the peak powers generated are typically 500 to 1000 MW, in the range from 2.3 to 5 GHz.
Abstract: The design and operating characteristics of relativistic, electron beam magnetrons are described. The magnetrons are comprised of a pulsed field‐emission cathode (∼360 kV, ∼15 kA, ∼30 nsec) and several coupled resonators embedded in the anode block. The tubes are designed to work at fixed frequency, in the range from 2.3 to 5 GHz. The peak powers generated are typically 500 to 1000 MW.
184 citations
TL;DR: Gear that offers theoretically distortionless encoding of Cartesian event positions into pulse charge ratios is discussed, and Electron beam images taken with such an anode are shown, and confirm the usefulness of the approach.
Abstract: Microchannel plates (MCPs) are frequently employed with resistive anodes to detect charged particles or photons and yield analog signals from which event positions can be decoded. We discuss an anode geometry devised by C.W. Gear that offers theoretically distortionless encoding of Cartesian event positions into pulse charge ratios. Electron beam images taken with such an anode are shown, and confirm the usefulness of the approach.
177 citations
Patent•
2 Jan 1979TL;DR: A bipolar collector-separator for electrochemical cells consists of a molded aggregate of electroconductive graphite and a thermoplastic fluoropolymer combined in a weight ratio of 2.5:1 to 16:1 as discussed by the authors.
Abstract: A bipolar current collector-separator for electrochemical cells consists of a molded aggregate of electro-conductive graphite and a thermoplastic fluoropolymer combined in a weight ratio of 2.5:1 to 16:1. The bulk resistivity of such a molded bipolar current collector-separator is less than 4×10 -3 ohm inches (Ω in.). It has excellent corrosion resistance to a variety of feedstocks such as brine, aqueous HCl, etc. and to various electrolysis products such as caustic, chlorine, hydrogen, etc. In one alternative form the anodic side of a current collector-separator for a water electrolyzer is covered by a thin layer of a passivated metallic foil thus protecting the graphite current collector against attack by oxygen.
171 citations
Patent•
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TL;DR: In this article, an X-ray tube comprising a cathode electrode including a filament for emitting electrons and a focusing electrode having a focusing groove adapted to contain the filament, and an anode electrode opposing the cathode and maintained at a high potential which is positive relative to the filament is formed as a substantially flat surface.
Abstract: In an X-ray tube comprising a cathode electrode including a filament for emitting electrons and a focusing electrode having a focusing groove adapted to contain the filament, and an anode electrode opposing the cathode electrode and maintained at a high potential which is positive relative to the filament, an electron emitting region of the filament facing the anode electrode is formed as a substantially flat surface, and the filament, the focusing electrode and the anode electrode are arranged such that a portion of the anode electrode upon which electron collide will be positioned in a focal plane of a cathode lens formed by the filament, the focusing electrode and the anode electrode.
131 citations
117 citations
TL;DR: In this paper, the preparation of photosensitive anodic Bi2S3 films is described and the quantum yield of the photocurrent, which approaches unity above 2 eV, has been measured as a function of the wavelength of excitation, and the results have been used to determine the absorption spectrum.
113 citations
Patent•
12 Jul 1979
TL;DR: An electrolysis cell is a housing containing a plurality of alternating anode units and cathode units, and an ion permeable membrane sheet disposed therebetween and having in direct contact with the opposite sides of the membrane sheet a porous anode and a porous cathode as mentioned in this paper.
Abstract: An electrolysis cell comprising a housing containing a plurality of alternating anode units and cathode units and an ion permeable membrane sheet disposed therebetween and having in direct contact with the opposite sides of the membrane sheet a porous anode and a porous cathode, said cathode units comprising a pair of spaced foraminous cathodes of the same polarity forming a space for catholyte therebetween and means for flowing aqueous electrolyte through the catholyte space of the cathode unit and means for removing electrolysis products, the anode units comprising a pair of spaced foraminous anodes forming a space for anolyte therebetween, means for flowing aqueous halide solution through the said anolyte space and means for removing electrolysis products therefrom and means for uniformly compressing the units and membranes together and to a novel method of generating halogens by electrolysis of aqueous halide solutions.
Patent•
1 May 1979TL;DR: In this paper, the authors proposed a circuit for the uniform charging and discharging of electrochemical storage cells of the alkali metal and chalcogen type having a protective element in the circuit.
Abstract: Circuit for the uniform charging and discharging of electrochemical storage cells of the alkali metal and chalcogen type having a protective element in the circuit. The protective element is a container filled with a chemical compound which easily dissociates and easily recombines. The outer surface of the container forms an anode. An electrically conducting rod which forms a cathode extends into and also out of the container, and is electrically insulated in its mounting.
TL;DR: An analysis of unipolar electrolyzer equipment is reported which allows estimation of the different contributions to cell voltage of the reversible potential, of electronic and ionic ohmic resistance, and of the electrode overvoltages.
Abstract: An analysis of unipolar electrolyzer equipment is reported which allows estimation of the different contributions to cell voltage of the reversible potential, of electronic and ionic ohmic resistance, and of the electrode overvoltages. A technique is described which allows performance data for a commercial electrolyzer to be decomposed to give the ohmic resistance contribution as well as the sum of the Tafel slopes for the anodic and cathodic processes. Substantial time variation of both the anode and cathode overvoltages was observed, with the rate and magnitude of this variation being dependent on current density. In light of these results, appropriate methods for long‐term evaluation of new electrode materials are discussed, and a reliable long‐term‐test cell is described. Representative data obtained on prolonged operation of cathodic and anodic electrode samples are reported.
TL;DR: In this article, a trickle bed electrochemical reactor has been developed for the production of dilute alkaline peroxide solutions by reduction of oxygen, and the effects of current density, oxygen pressure and flow rate, electrolyte concentration, graphite particle size, bed thickness and length were investigated.
Abstract: A trickle bed electrochemical reactor has been developed for the production of dilute alkaline peroxide solutions by reduction of oxygen. Oxygen gas and sodium hydroxide flow concurrently downward through a cell which consists of a thin packed cathode bed of graphite particles separated from the anode plate by a porous diphragm. Current flows perpendicular to the flow of electrolyte. The effects of current density, oxygen pressure and flow rate, electrolyte concentration and flow rate, graphite particle size, bed thickness and length were investigated. In 2 M NaOH peroxide solutions of 0.8 M have been produced at 60% efficiency with current densities of 1200 A m−2 and cell voltages of 1.8 V. A bipolar cell stack consisting of five cells has been tested.
TL;DR: The application of the Pourbaix diagram to the prediction and understanding of the thermodynamic stability of semiconductor materials is discussed in this paper, with the aid of flat band potential information.
TL;DR: In this article, coal is consumed within an aqueous electrolyte to produce gaseous oxides of carbon at the anode and hydrogen at the cathode, and an abrupt and reproducible jump in potential is observed which suggests at least two different mechanisms for the overall process.
Patent•
14 May 1979TL;DR: In this paper, a three compartment membrane cell for the electrolyzing aqueous alkali metal halides at low cell voltages and with high cathodic current efficiencies is described.
Abstract: The invention describes a pressurized, three compartment membrane cell for the electrolyzing aqueous alkali metal halides at low cell voltages and with high cathodic current efficiencies. Unitary electrode-electrolyte structures, in the form electrochemically active electrodes physically bonded to ion transporting permselective membranes divide the cell into anode, cathode and buffer compartments. The buffer compartment feed is pressurized to maintain at a positive pressure differential with respect to the anode and cathode compartment feeds. The flexible unitary electrode-membrane electrolytes are forced outwardly against electronically conductive anode and cathode current collectors to provide uniform, constant and controllable contact between the bonded electrodes and thereby minimizing ohmic losses. A three compartment cell operated in this fashion not only minimizes the voltage required to electrolyze the halide solution, but also increases the cathodic current efficiency at high caustic concentrations by providing multiple hydroxide rejection stages in a single cell process. The improvement in cathodic current efficiency is realized by forming a lower caustic concentration in the buffer compartment than in the cathode compartment thereby reducing backmigration of OH- ions into the anode compartment.
Patent•
9 Apr 1979
TL;DR: In this paper, a battery comprising an inert container housing a plurality of corrosion resistant gas depolarized metal cathode elements in hollow box-like form and consumable anode elements mounted on non-consumable metal supports is described.
Abstract: A battery comprising an inert container housing a plurality of corrosion resistant gas depolarized metal cathode elements in hollow box-like form and consumable anode elements in spaced relationship with said cathode elements. At least one wall of each cathode element has a gas-permeable porous cathode formed of sintered particles impregnated with a catalyst and, on the inside, with a hydrophobic resin. The consumable anode elements are mounted on non-consumable metal supports so as to be removable (with or without their supports) and replaceable in the container. In operation, depolarizing gas is fed inside the cathode elements and an electrolyte is maintained between the facing cathodes and anodes.
TL;DR: Cell populations of S. cerevisiae in a fermentor could be continuously estimated by using this electrochemical method and current differences between the two electrodes were proportional to populations of microbial cells in cultures of Saccharomyces Cerevisiae and Lactobacillus fermentum.
Abstract: Determinations of microbial populations were carried out by using a new electrode system composed of two electrodes. Each electrode was constructed from a platinum anode and a silver peroxide cathode. The anode of the reference electrode was covered with cellulose dialysis membrane. The response time of the electrode system was 15 min in culture broth, and current differences between the two electrodes were proportional to populations of microbial cells in cultures of Saccharomyces cerevisiae and Lactobacillus fermentum. Current differences were reproducible; the average relative error was 5%. Furthermore, cell populations of S. cerevisiae in a fermentor could be continuously estimated by using this electrochemical method.
Patent•
16 Jul 1979
TL;DR: In this article, a method and apparatus for providing germicidal and healing treatment of tissue such as bone was proposed, where an electrode of silver or like material was applied to a living tissue site to be healed, initially a direct voltage is applied to the electrode of a polarity driving the electrode as an anode to release silver ions to create a germicidal environment at the site.
Abstract: A method and apparatus for providing germicidal and healing treatment of tissue such as bone wherein an electrode of silver or like material is applied to a living tissue site to be healed, initially a direct voltage is applied to the electrode of a polarity driving the electrode as an anode to release silver ions to create a germicidal environment at the site, and thereafter a direct voltage of opposite polarity is applied to the electrode driving it as a cathode to stimulate healing of the tissue at the site. The apparatus is implanted in the body of a patient, and in one embodiment a battery is connected through a switch to the electrode and a reference electrode, the switch initially connecting the electrode as an anode and thereafter changeable by an external operator such as a magnet to connect the electrode as a cathode. In another embodiment, another electrode and an element cooperate with the treating electrode to form a galvanic couple with the treating electrode to create a germicidal environment and a predetermined time thereafter the arrangement changes to a biogalvanic couple with body fluid to cause healing of the tissue. In either embodiment a wave shaping circuit can be operatively associated with the treating electrode to facilitate external monitoring of the apparatus when implanted.
Patent•
13 Nov 1979
TL;DR: In this article, a rotating anode X-ray tube with a shroud surrounding and close to at least part of the anode is proposed, which collects back scattered electrons and can also be fluid cooled.
Abstract: In rotating anode X-ray tubes it has not been the practice to provide anode cooling because of problems in arranging coolant flow. A further problem which has arisen, particularly in tubes for computerized tomography which should have precisely defined focal spots, is off-focus radiation apparently resulting from back scattered electrons hitting the tube target away from the focal spot. It is here proposed to provide a rotating anode X-ray tube with a shroud surrounding and close to at least part of the anode. This is extended towards the electron gun with an aperture through which the electron beam travels and an X-ray emissive window. The shroud collects back scattered electrons and can also be fluid cooled. The window provides some collimation and the edges can be shaped to restrict the focal spot as viewed away from the main X-ray beam.
1 Jun 1979
TL;DR: The NASA-Redox system as discussed by the authors uses two fully soluble Redox couples, anode and cathode fluids, as active electrode materials separated by a highly selective ion exchange membrane.
Abstract: NASA-Redox systems are electrochemical storage devices that use two fully soluble Redox couples, anode and cathode fluids, as active electrode materials separated by a highly selective ion exchange membrane. The reactants are contained in large storage tanks and pumped through a stack of Redox flow cells where the electrochemical reactions (reduction and oxidation) take place at porous carbon felt electrodes. A string or stack of these power producing cells is connected in series in a bipolar manner. Redox energy storage systems promise to be inexpensive and possess many features that provide for flexible design, long life, high reliability and minimal operation and maintenance costs. These features include independent sizing of power and storage capacity requirements and inclusion within the cell stack of a cell that monitors the state of charge of the system as a whole, and a rebalance cell which permits continuous correction to be made for minor side reactions that would tend to result in the anode fluid and cathode fluids becoming electrochemically out of balance. These system features are described and discussed.
Patent•
10 May 1979
TL;DR: In this article, a cathodic protection system and method for steel reinforcement in concrete structures such as bridge decks, parking garage decks and highways utilizes platinized niobium or like metal wire anodes strategically positioned adjacent the concrete in a matrix of conductive carbonaceous material.
Abstract: A cathodic protection system and method for steel reinforcement in concrete structures such as bridge decks, parking garage decks and highways utilizes platinized niobium or like metal wire anodes strategically positioned adjacent the concrete in a matrix of conductive carbonaceous material. The anode and matrix are preferably positioned in slots saw cut in the concrete surface avoiding the disposition of a conductive and wear resistant surface overlay which is not only expensive but which may exceed the design limitations of the structure. An impressed protective cathodic protection current is provided between the anodes and the steel of the structure. At places where the anode crosses in close proximity to reinforcing steel which may be exposed by the slot, or at places where cathodic protection current is not desired, a plastic sleeve may be placed over the anode. The anode may be connected directly to a current source or it may be spliced to an insulated copper lead wire and be brought down through the deck of the structure to be connected to the rectifier beneath the deck. Although more than one anode may be connected to any single rectifier circuit, it is preferred to have as many individual circuits as practicable to assist in analyzing the system performance with either permanently installed reference electrodes or portable reference electrodes.
Patent•
19 Mar 1979
TL;DR: In this paper, a preshaped form of electrically conductive material is disposed in a volume of electrolyte, such as seawater, to serve as a cathode, one or more are anodes disposed in proximity to the form, and a direct electrical current is established between the electrodes for a period of time sufficient to accrete a solid covering of material on the form.
Abstract: By establishing a direct electrical current between electrodes in an electrolyte like seawater, calcium carbonates, magnesium hydroxides, and hydrogen are precipitated at the cathode, while at the anode, oxygen and chlorine are produced. The electrodeposition of minerals is utilized to construct large surface area (i.e. greater than 100 square feet) structures, building components and elements of a hard, strong material (i.e. 1000-8000 P.S.I. compression strength). To make a large surface area structure, building component or element of hard, strong material, a preshaped form of electrically conductive material is disposed in a volume of electrolyte, such as seawater, to serve as a cathode, one or more are anodes disposed in proximity to the form, and a direct electrical current is established between the electrodes for a period of time sufficient to accrete a solid covering of material on the form.
Patent•
30 Jul 1979
TL;DR: In this article, a cell for the electrolytic deposition of aluminum at low temperatures and low electrical potential is described, where the anode is the sole source of aluminum and comprises a composite mixture of an aluminous material such as aluminum oxide and a reducing agent.
Abstract: A cell for the electrolytic deposition of aluminum at low temperatures and low electrical potential in which the anode is the sole source of aluminum and comprises a composite mixture of an aluminous material such as aluminum oxide and a reducing agent. Conductor means of higher electrical conductivity than the mixture are provided to conduct substantially the entire anodic current to the active anode surface thereby reducing the voltage drop through the highly resistive composite mixture. The mixture may be employed in a self-baking mode or be prebaked. Alternatively, the mixture may be in a particulate form and contained within a porous membrane which passes the electrolyte or other dissolved material while withholding undissolved impurities. The cell may have bipolar electrodes and may be used in combined winning and refining configurations.
Patent•
28 Jun 1979
TL;DR: A battery system having a zinc containing anode in an alkaline electrolyte produced in a manner to substantially avoid dendritic growth and anode shape change with additives added to the electrolyte and/or anode to assist therein is described in this paper.
Abstract: A battery system having a zinc containing anode in an alkaline electrolyte produced in a manner to substantially avoid dendritic growth and anode shape change with additives added to the electrolyte and/or anode to assist therein.
Patent•
11 Oct 1979TL;DR: In this paper, a surfactant is added in such a way that, directly or upon wetting of the anode by the electrolyte, there is an adsorption of surfactants on the surface of the zinc anode material, whereby hydrogen evolution is inhibited.
Abstract: Hydrogen evolution in cells having zinc anodes is reduced or eliminated by incorporating in the cell a surfactant which is a complex phosphate ester of a surfactant of the ethylene oxide-adduct type. This surfactant is added in such a manner that, directly or upon wetting of the anode by the electrolyte, there is an adsorption of surfactant on the surface of the zinc anode material, whereby hydrogen evolution is inhibited. The surfactant is desirably present in the cell in an amount of from 0.001% to 5% by weight of the zinc component of the cell.
TL;DR: In this article, the standing electrode potentials as well as the coupled electrode potential were measured in the catholyte (,, Rochelle salt) and in the anolyte in a two-chamber galvanic cell enabled the simultaneous study of both oxidation and reduction processes involved in electroless copper deposition.
Abstract: A two‐chamber galvanic cell enabled the simultaneous study of both oxidation and reduction processes involved in electroless copper deposition. The standing electrode potentials as well as the coupled electrode potentials were measured in the catholyte (, , Rochelle salt) and in the anolyte (, , Rochelle salt). The current passing during coupling was dependent on coupling time, catholyte and anolyte compositions, and the activation of the anode. The order of the deposition process as calculated from the coupling current compared favorably with that obtained by direct weight measurements. Evan's diagrams were constructed and used to correlate electrode potential, coupling current, and the mixed potential with the rate of the electroless deposition process.
Patent•
11 Jul 1979TL;DR: In this paper, a field emission electron gun including a cathode, a control electrode, an anode, and a source of a D.C. voltage to be applied between the cathode and the anode is presented.
Abstract: A field emission electron gun including a cathode, a control electrode which is disposed in the vicinity of the cathode, an anode which is disposed for accelerating electrons emitted from the cathode, and a source of a D.C. voltage to be applied between the cathode and the anode. Also, there is provided a switching arrangement capable of changing-over a potential of the control electrode between ground potential and a potential of the cathode, and an arrangement capable of varying relative positions of the cathode and the control electrode.
Patent•
19 Jul 1979TL;DR: In this article, a plurality of radiation sources are arranged to define a scanning path and the sources are successively actuated to produce successively operative beams each of duration sufficient to be recorded, for example by means of a conventional moving photographic cassette.
Abstract: In an illustrated embodiment a plurality of radiation sources are arranged to define a scanning path and the sources are successively actuated to produce successively operative beams each of duration sufficient to be recorded, for example by means of a conventional moving photographic cassette. For the case of a linear scan path, an elongated anode may have a succession of continuously energized cathodes, each cathode having an associated blocking screen and being momentarily actuated by removal of the blocking potential. The successive cathodes are actuated in synchronism with the movement of a film cassette, for example, in any suitable manner, or electronic image storage may be utilized in the form of a stationary array of photodetector elements and the required number of arrays of storage units, with electronic sequencing control.