Abstract: Improved electrolytic cells and methods for producing metals by electrolytic reduction of a compound dissolved in a molten electrolyte are disclosed. In the improved cells and methods, a protective surface layer is formed upon at least one electrode in the electrolytic reduction cell and, optionally, upon the lining of the cell. This protective surface layer comprises a material that, at the operating conditions of the cell: (a) is not substantially reduced by the metal product; (b) is not substantially reactive with the cell electrolyte to form materials that are reactive with the metal product; and, (c) has an electrochemical potential that is more electronegative than that of the compound undergoing electrolysis to produce the metal product of the cell. The protective surface layer can be formed upon an electrode metal layer comprising a material, the oxide of which also satisfies the protective layer selection criteria. The protective layer material can also be used on the surface of a cell lining.

Abstract: Process for the manufacture of alkali metal sulphide, in which an electrolysis cell is used in which a membrane which is selectively permeable to cations separates an anode chamber containing an anode from a cathode chamber containing a cathode, an electrolyte containing alkali metal is electrolyzed in the anode chamber and an aqueous solution of alkali metal polysulphide is electrolyzed simultaneously in the cathode chamber.

Abstract: A submerged pool purifier which has a cell including an immersed enclosure (20) to which a number of electrodes (28) are disposed in parallel array along with a masking grid (29) on each electrode. Wires (30) are routed inside existing pool piping connected to opposed electrodes on one end and a power supply (58) to the other. The wires immerge from the pool piping at a convenient location and the egress is interfaced with a compression fitting (36) making the connection watertight. The power supply changes AC electrical power to DC and a polarity reversing timer (60) reverses the polarity at regular intervals to the cell eliminating scale deposits. The DC current to the electrodes that are submerged in pool water containing dilute halite salt cause an electrolytic action ultimately producing nascent oxygen and sodium hypochlorite. In a second embodiment, the electrodes utilize a copper-silver alloy creating copper and silver ions for pool purification.

Abstract: The instant invention pertains to a process to produce an electrically conducting, polymeric article by (a) applying a fluid containing a catalytic, electrically conducting polymer with a metal moiety chemically combined therewith to at least a surface portion of a substrate; (b) drying the fluid to form a coating adhering to at least a surface portion of the substrate; and (c) optionally repeating steps (a) and (b) to attain a desired surface loading.

Abstract: Gas diffusion oxygen cathodes, oxygen consuming electrochemical cells utilizing such cathodes, and a method of preparing such cathodes are disclosed. The cathode comprises an electronically conductive porous body defining respective gas and electrolyte contacting surfaces. The cathode is prepared by forming the porous body, disposing the electrolyte contacting the gas contacting surface with a gaseous atmosphere. Current is passed through the porous body at a degree of electrode polarization much higher than normal whereby modification of the electrode material is effected. If desired, a transition metal macrocycle catalyst may be incorporated in the electrode and is subjected to pretreatment as well. The inventive electrodes exhibit superior voltage performance under oxygen reduction polarization conditions.

Abstract: A process for making a polymer-modified electrode comprising electrocatalytic metal, a metal substrate (1) and small polymer particles (2) by contacting the substrate with a (preferably aqueous) dispersion containing the particles and also a dissolved compound of electrocatalytic metal of greater electronegativity than the metal of the substrate, whereby contacting the substrate with the dispersion cause spontaneous deposition of electocatalyst, which in turn causes desposition of the particles onto the substrate, and then drying the substrate and deposit at a temperature below the softening point of the polymer. The deposited particles retain their shape and only a few are mutually contiguous, with the result that the poison resistance of the electrodes is increased and their overpotentials are reduced. Also, electrodes in which at least 70% of the particles are fully spaced from their neighbors and the amount of particles deposited is preferably from 0.0005 to 2 cm.sup.3 m.sup.2 of substrate surface.

Abstract: The present invention concerns electrodes for use in electrochemical processes, particularly as cathodes for hydrogen evolution in cells for the electrolysis of alkali metal halides, the electrodes comprising an electrocatalytic ceramic coating obtained by thermal deposition. Elements of the groups IB, IIB, IIIA, IVA, VA, V B; VI A; VI B and VIII are added to the solutions or dispersion of precursor compounds of electrocatalytic ceramic materials, the solutions or dispersions being thermally decomposed to obtain the coating.The surface of the doped coating thus obtained is substantially immune to poisoning by metal impurities, when the electrode according to the present invention is used as cathode in poisoned alkali solutions.

Abstract: Gas diffusion electrodes and gas generating or consuming electrochemical cells utilizing the same are disclosed. The electrode includes an electronically conductive and electrochemically active porous body defining respective gas and electrolyte contacting surfaces, with an ionomeric ionically conductive gas impermeable layer covering the electrolyte contacting surface. The layer includes a layer of a hydrophilic ionic polymer applied directly to the electrolyte contacting surface and a membrane of a hydrophilic ion exchange resin overlying the polymer layer.

Abstract: An electrochemical cell including an electrode comprising Magneli phase titanium oxide is disclosed for use with reduction oxidation reactions. The use of the Magneli phase titanium oxide electrode advantageously inhibits certain redox back reactions.

Abstract: The invention is a method of making an electrode which comprises applying to an electroconductive nickel-containing substrate a coating solution of metal oxide precursor compound(s) and an etchant capable of etching the surface of the substrate and/or any previously applied coating, heating to remove volatiles from the so-coated substrate to cause the metal values of the precursor compounds and those etched from the substrate or previous coating to be concentrated and recoated on the substrate or previously applied coating, and further heating, in the presence of oxygen, air or an oxidizing agent, to a temperature sufficient to oxidize the metal values.

Abstract: The polarizable electrode in an electrolyte comprises an electrically conductive conductor, advantageously metal or carbon, which is surrounded by an inner layer made of an electrically conductive plastic, which has a high stability to action by the electrolyte and does not lose its closed structure on insertion of the electrode so that protection of the electrically highly conductive conductor against electrochemical or chemical action is guaranteed. The inner layer is enclosed by an outer layer made of electrically conductive plastic, which loses its closed structure by the electrochemical processes occurring and which expands to a large volume so that the active working surface of the electrode is increased by the desired porosity.

Abstract: The morphology of a coating of an oxyfluoride of cerium on a conductive substrate is improved by addition of tantalum, niobium and/or other pentavalent metals. Whereas a cerium oxufluoride coating shows cracks which may extend throughout the entire thickness of the coating, thus exposing finite portions of the substrate to corrosive attack, the pentavalent-doped coating has a substantially impervious structure. In addition to improvement of the coating morphology, the electrical conductivity is increased. The pentavalent-doped cerium oxyfluoride can be produced by electrodeposition or sintering. Coatings, substrates or bodies of this material may be employed as non-consumable anodes in molten aluminum electrowinning cells, as chemical sensors, or for corrosion protection and other applications.

Abstract: An electrode comprising a first structure of a low conductivity non-metallic material spaced from a second structure of a high conductivity material which acts as a current distributor to the first structure, and a low melting metal or alloy of bismuth between and in contact with the structures.

Abstract: A ceramic/metal composite material comprises a surface ceramic coating comprising an oxidized alloy of copper stabilized by being in solid solution with nickel oxide or manganese oxide on a substrate which is an oxidation resistant alloy essentially devoid of copper or any metal which oxidizes more readily than copper. The composite is made by oxidizing a copper-based alloy on a substrate and simultaneously oxidizing the substrate surface to form an oxygen-barrier interface, for example a chromium oxide layer formed on an alloy of chrominum with nickel, iron and/or cobalt. The composite may be used as anode substrate for a cerium oxyfluoride coating used in aluminum electrowinning.

Abstract: Disclosed is a process for fabricating a thin, porous, electronically conductive, high-surface area film proximate the surface of a solid polymer electrolyte membrane. The film has highly desirable characteristics as a surface electrode. Films may be formed on both sides of the membrane to form a bi-polar structure useful in various processes, including chloralkali processes.

Abstract: Renewable modified composite electrodes for electrochemical applications are provided by homogeneous structures of a conductive filler and a modifier dispersed within a polymer matrix or binder. The modifiers may provide characteristics of electroactivity, inclusion, adsorption or electrocatalysis to the surface of the electrode in a solution. After use, the electrode may be renewed by removing a surface portion and thereby exposing a fresh portion of the homogeneous structure.

Abstract: Chlorine is generated by electrolyzing aqueous alkali metal chloride in a cell wherein the anode and cathode are separated by and in contact with an ion exchange diaphragm and wherein the anode and/or cathode contains particles of an electroconductive catalytic material along with particles of an electroconductive extender bonded to the membrane.

Abstract: A non-consumable anode of the type comprising an oxide ceramic coating on a metal substrate, for molten salt electrolysis, namely the electrowinning of metals such as aluminum, has an electronically-conductive oxygen barrier layer between the oxide ceramic coating and the substrate, the oxygen barrier layer containing chromium oxide. Usually, the oxygen barrier layer is a surface film integral with a chromium-containing alloy substrate, comprising 10 to 30% by weight of chromium, 55 to 90% of nickel, cobalt and/or iron and up to 15% of aluminum, titanium, zirconium, yttrium, hafnium or niobium. The ceramic oxide coating may comprise copper oxide in solid solution with at least one further oxide; nickel ferrite; copper oxide and nickel ferrite; doped, non-stoichiometric or partially substituted spinels; or rare earth metal oxides or oxyfluorides.

Abstract: An electrode for precision electric discharge machining having an improved machining rate and surface smoothness with respect to conventional graphite and copper electrodes. The electrode is formed by silicon or other materials which has the same characteristics as silicon, a base of a low melting point metal or an alloy of such a low melting point metal is covered with a layer composed of a mixture of the metal and a high resistivity inorganic compound. The outer layer may be formed by adhesion or by thermal spraying or by a powder metal sintering technique.

Abstract: A process for the formation of alumina containing carbon fiber mats is provided. The process comprises dispersing an alumina precursor solution in the mat, converting the precursor to an insoluble hydroxide precipitate and hydrolizing the precipitate to form alumina nodules dispersed throughout the mat. Also provided is an alumina containing carbon fiber mat comprising carbon fibers and nodules of alumina, which are substantially uniformly dispersed throughout the mat, and a sodium sulfur cell having a sulfur compartment containing such a mat.

Abstract: An elastomeric electrode having an electrically conductive base, a protective layer enclosing the base formed of an elastomeric material having electrically conductive material selected from the group consisting of highly conductive carbon black, graphite, and glassy carbon distributed therein and present in the amount of 10 to 30 parts by weight to 100 parts by weight of the elastomeric material. A terminal extends from the base to exteriorly of the protective layer.

Abstract: Disclosed are electroactivated shaped articles, well adapted as cathode elements and composites, especially for electrolytic cells for the electrolysis of sodium chloride. The articles include a mass of fibrous material consolidated in a matrix of fluoropolymer binder wherein at least a portion of the fibers are electrically conductive. The shaped articles have a resistivity of less than 0.4 ohm cm, and have at least one electrocatalytically active agent uniformly dispersed therethrough. The electrocatalytically active agent(s) is (are) selected from Raney metals or Raney alloys depleted in fugitive metal values.

Abstract: The present invention concerns a method for preparing electrodes for use in electrochemical processes, said electrodes being constituted by a conductive support whereto an electrocatalytic coating is applied by galvanic deposition from a galvanic plating bath which additionally contains the groups IB, IIB, IIIA, IVA, VA, VB, VIB, VIII Of the periodic table.The electrodes of the invention, obtainable according to the method of the invention, when used as cathodes in membrane or diaphragm chlor-alkali cells, exhibit low hydrogen overvoltages, constant with time, and are substantially immune to poisoning by iron, mercury or other metal impurities present in the alkaline solutions.

Abstract: An electrochemical cell including an electrode comprising Magneli phase titanium oxide is disclosed for use with reduction oxidation reactions. The use of the Magneli phase titanium oxide electrode advantageously inhibits certain redox back reactions.

Abstract: A massive anode is assembled from many, closely packed modular anodes. Although close-packed, the modular anodes are nevertheless spaced apart one from the other. The massive anode has at least substantial inflexibility. It can be particularly useful where a flexible cathode may move toward, and even contact, the anode, e.g., in electrogalvanizing where a moving sheet from a metal coil being coated may thump against the anode. The individual modular anodes provide a collective, generally planar front face toward the cathode. Individual, adjacent modular anodes can be separated at least in part by dielectric spacing members which have portions extending toward the cathode, thereby initially receiving any impact from the cathode.

Abstract: Electrode structures of solid polymer electrolyte type for use in electrolysis are disclosed, (i) in which an adhering layer containing fine particles loaded with a .beta.-lead dioxide powder is formed on one surface of an ion-exchange membrane serving as a solid polymer electrolyte, and an electrodeposited layer of lead dioxide being formed on the surface of the adhering layer, and (ii) in which an electrodeposited layer of lead dioxide having dispersed therein fine particles loaded with a .beta.-lead dioxide powder is formed electrolytically between an ion-exchange membrane serving as a solid polymer electrolyte and a current collector positioned close to the ion-exchange membrane, to thereby form a unitary assembly. The present electrode structures are useful for production of ozone by electrolysis of water and for production of peroxides by electrolysis of aqueous solutions.

Abstract: Renewable modified composite electrodes for electrochemical application are provided by homogeneous structure of a conductive filler disposed in a polymeric matrix or binder containing a modifier in the polymer chain. The modifier provides distinctive characteristics of electroactivity, inclusion, acidic/basic, complexing/chelating or electrocatalysis to the surface of the electrode in a solution. After use, the electrode may be renewed by removing a surface portion and thereby exposing a fresh portion of the homogeneous structure.

Abstract: An improved cathode structure for Hall-Heroult cells for the electrolytic production of aluminum metal. This cathode structure is a preform fiber base material that is infiltrated with electrically conductive titanium diboride using chemical vapor infiltration techniques. The structure exhibits good fracture toughness, and is sufficiently resistant to attack by molten aluminum. Typically, the base can be made from a mat of high purity silicon carbide fibers. Other ceramic or carbon fibers that do not degrade at temperatures below about 1000 deg. C can be used.

Abstract: An electrode catalyst comprising a lead dioxide electrically deposited layer, the layer having particles containing .beta.-lead dioxide powder dispersed therein, and a method for producing the electrode catalyst are disclosed. The particles contain .beta.-lead dioxide powder and optionally an electrolytic cocatalyst selected from PTFE, agar, gelatin, a perfluoro ion exchange resin and the like. The present electrode catalyst is useful for production of ozone by electrolysis of water and for production of peroxides by electrolysis of aqueous solutions.

Abstract: A platinum black air cathode has an active layer and a support layer. The active layer comprises platinum black plus hydrophobic binder, typically a fluorinated polymer. The support layer may be made up from carbon black bound with a halopolymer binding agent. Such combination can provide for economical utilization of active ingredient without sacrifice of cathode structural integrity. To assist in this structural integrity, a thin support mesh may be used, preferably with the support layer. There can also be employed between the active layer and the support layer a porous bonding layer, which can find broader utilization with layered gas diffusion electrodes in general. For highly desirable, greatly extended operation of the platinum black air cathode, the cathode can be operated intermittently, or anodically polarized or be subjected to infrequent voltage suppression, as well as being involved with any combination of the foregoing.

Abstract: A process for separation of hafnium tetrachloride from zirconium tetrachloride and electrode is disclosed. Zirconium tetrachloride containing hafnium tetrachloride in natural ratio dissolved in a molten salt is reduced in the first phase electrolysis using an anode composed of a substance formed by firing a mixture of more than one kind of compound selected from the group consisting of silica, silicate containing zirconium or zirconium oxide and carbon with a binder under maintenance of an initial concentration of the zirconium tetrachloride in order to produce zirconium trichloride containing a hafnium content lower than that of the zirconium tetrachloride at a cathode.

Abstract: An electrode is provided which is formed by the metallurgical bonding technique of diffusion bonding the backplate, conductor elements and electrode surface together, then applying the catalytic coating to the electrode surface, and bonding the backplate to an electrical conducting plate.

Abstract: An improved alumina reduction cell is described in which the carbonaceous cathode includes refractory hard metal shapes forming the true cathode surface and inert refractory protective sleeves for the refractory hard metal shapes. Reduced amounts of refractory hard metal material are employed through an improved refractory hard metal support system.

Abstract: A square blocked anode with first and second opposite flat faces and rectangular sidewalls joining the flat faces has a diagonal hole formed between one sidewall and a second face of the anode. Insulation is stripped from a distal end of a multiple strand insulated wire lead and the stripped end is inserted through the sidewall into the diagonal opening. Wire strands which emerge from the opening in the second surface of the anode are spread around the opening and solder may be applied to the spread strands. The square anode is fitted within a capsule having a square body with inner walls similar to the anode and slightly larger than corresponding surfaces of the anode. The insulated wire lead which emerges from the diagonal opening in a sidewall engages an inner surface of the capsule and an opposite sidewall of the anode engages an opposite inner surface of the capsule in friction fit, holding the anode in the capsule after the anode with the emerging wire lead are pressed in the capsule.

Abstract: A redox electrode for determining nitrous acid and nitrosyl compounds in aqueous, acidic solution consists of a metallic conductor on which an n-conducting metal oxide surface is present.

Abstract: A composite hydrogen purification membrane comprises an anode for hydrogen oxidation, a cathode for hydrogen reduction, with a proton conductor disposed between and in contact with the anode and the cathode. Electrons are conducted between the anode and cathode through an external connection, with the electron flow generated by the difference in hydrogen partial pressure between the anode and cathode sides of the membrane. Thus the composite hydrogen purification membrane provides high hydrogen permeability and selectivity relative to the impurities in a feed gas, producing pure hydrogen without requiring an external voltage source.

Abstract: A cathode for electrolysis, particularly of a sodium chloride aqueous solution by an ion-exchange membrane method, and a process for producing the same, the cathode comprising a conductive base having a nickel surface and having provided thereon (a) at least one platinum group component selected from the group consisting of a platinum group metal, a platinum group metal oxide, and a platinum group metal hydroxide, and (b) at least one cerium component selected from the group consisting of cerium, cerium oxide, and cerium hydroxide, retaining a markedly reduced hydrogen overpotential for an extended period of time and exhibiting excellent resistance to impurities in the electrolytic solution.

Abstract: Several types of new microelectronic devices including diodes, transistors, sensors, surface energy storage elements, and light-emitting devices are disclosed. The properties of these devices can be controlled by molecular-level changes in electroactive polymer components. These polymer components are formed from electrochemically polymerizable material whose physical properties change in response to chemical changes, and can be used to being about an electrical connection between two or more closely spaced microelectrodes. Examples of such materials include polypyrrole, polyaniline, and polythiophene, which respond to changes in redox potential. Each electrode can be individually addressed and characterized electrochemically by controlling the amount and chemical composition of the functionalizing polymer. Sensitivity of the devices may be increased by decreasing separations between electrodes as well as altering the chemical environment of the electrode-confined polymer.

Abstract: A process which comprises thermally decomposing in an electrically heated vibrating helical conveyor, manganese carbonate (MnCO.sub.3 x H.sub.2 O) into a manganese oxide (predominantly of Mn.sub.2 O.sub.3 x Mn.sub.5 O.sub.8) catalyst at about 500.degree. C., and processing this catalyst into a highly active electrode paste by dry intensive mixing with a carbon-containing conductive material (carbon black, graphite or activated carbon) and PTFE as the binder. The resulting electrode paste can be rolled into a supporting net made from Ni or Ag. Also a two-step mixing process in which the catalyst powder is first premixed with small amounts of a conductive agent and a binder, compacted and granulated, and then combined with the larger residual amount of the intended amounts of conductive agent and binder in a second mixing step.

Abstract: A pressure-molded, rigid, high surface cathodic or anodic electrode of low electrical resistance and good mechanical strength and resistance to corrosion comprising non-dissolving, electrically-conducting metal particles of high specific surfaces and fractal structure which are bound with up to 15% by weight of aluminum phosphate.

Abstract: This invention relates to a lithum-containing carbon anode employed in the process of producing aluminum metal where the lithium compounds in an amount of 0.1 to 1.5 percent by weight were added into the carbon mass made of pitch and calcined coke to produce a Soderberg anode and carbon mass of prebaked anode. Compared with the ordinary carbon anode used in the production of aluminum, the anode overvoltage will be reduced about 100 to about 200 mV. Therefore, the energy consumption will be decreased by about 300 to about 600 Kwh. In addition, the current efficiency will be increased by 1 to 2 percent.

Abstract: Disclosed herein is a gas sensor comprising a membrane for gas sensing which comprises a selective gas permeable membrane and a reaction layer attached thereto; and a counter electrode separated from the reaction layer of the membrane across an electrolyte; the reaction layer having the function of an electrode and comprising fine hydrophilic portions and fine hydrophobic portions.The specific gas in mixed gases having permeated the selective gas permeable membrane is immediately dissolved in the electrolyte having penetrated into the reaction layer and is ionized and the ion in the electrolyte moves to the counter electrode closely positioned to the reaction layer so that the specific gas concentration can be detected by means of the voltage difference or the like.

Abstract: A conductive silver/silver chloride composition consisting essentially of:(a) about 6 to about 10.5 parts by weight of a vinylidene chloride thermoplastic polymer having a glass transition value of above about 100.degree. F.;(b) at least a sufficient amount of an organic solvent capable of dissolving polymer (a);(c) about 47 to about 57 parts by weight of silver flake; and(d) about 8 to about 16 parts by weight of silver chloride.

Abstract: Cermet electrode compositions and methods for making are disclosed which comprise NiO--NiFe.sub.2 O.sub.4 --Cu--Ni. Addition of an effective amount of a metallic catalyst/reactant to a composition of a nickel/iron/oxide, NiO, copper, and nickel produces a stable electrode having significantly increased electrical conductivity. The metallic catalyst functions to disperse the copper and nickel as an alloy continuously throughout the oxide phase of the cermet to render the electrode compositon more highly electrically conductive than were the third metal not present in the base composition. The third metal is preferably added to the base composition as elemental metal and includes aluminum, magnesium, sodium and gallium. The elemental metal is converted to a metal oxide during the sintering process.

Abstract: Cermet electrode compositions comprising NiO-NiFe.sub.2 O.sub.4 -Cu-Ni, and methods for making, are disclosed. Addition of nickel metal prior to formation and densification of a base mixture into the cermet allows for an increase in the total amount of copper and nickel that can be contained in the NiO-NiFe.sub.2 O.sub.4 oxide system. Nickel is present in a base mixture weight concentration of from 0.1% to 10%. Copper is present in the alloy phase in a weight concentration of from 10% to 30% of the densified composition. Such cermet electrodes can be formed to have electrical conductivities well in excess of 100 ohm.sup.-1 cm.sup.-1. Other alloy and oxide system cermets having high content metal phases are also expected to be manufacturable in accordance with the invention.

Abstract: A method for the manufacture of catalyst electrodes with structurally connected carrier bodies, in which an excess of catalyst suspension is applied to the surface of the carrier body which thereafter is centrifuged off by rotation of the carrier body about an axis disposed perpendicularly to its surface. An aqueous suspension with Raney nickel as catalyst, which is particularly suitable as an example for the use in the coating method, has a dynamic viscosity of 10,000 to 50,000 mPa . s at a temperature of 20.degree. C. as well as a solids content of 55 to 75% by weight. An extraordinarily uniform coating can be acheived with the method of the present invention.

Abstract: The invention is an article comprising at least partially a catalytic, metal-containing, electrically conducting coordination polymer. In addition, this invention includes a process of manufacturing the article comprising applying a mixture containing a catalytic, metal-containing, electrically conducting coordination polymer to a substrate and drying said fluid to form a coating. This invention also encompasses an electrolytic cell comprising a cell body and a cathode spaced apart from an anode, said anode comprising a catalytic, metal-containing, electrically conducting coordination polymer. Another aspect of this invention is a process for generating reduction-oxidation reaction products comprising electrolyzing a solution in the above described electrolytic cell.

Abstract: An electrode, and method of producing same, including tungsten which has been heated in wet hydrogen at 1050.degree. C. for 5 to 10 minutes, then heated at about 1500.degree. C. for about three hours in a vacuum, and then further heated at about 2800.degree. C. for about 5 minutes in a vacuum.

Abstract: A hydrogen-evolution electrode comprising an electrically conductive substrate having thereon a coating comprising a chromium component, a titanium component and an oxide of at least one metal selected from the group consisting of nickel and cobalt, said chromium component and titanium component being present in proportions, in terms of atomic percentage, of 0.5 to 40% and 0.1 to 10%, respectively. The titanium component retards the dissolution rate of the chromium component. Accordingly, the electrode has a life several times as long as that of the conventional electrodes, and can exhibit an advantageously low hydrogen overvoltage for a prolonged period of time. Also, the electrode can be advantageously employed to produce an alkali product improved in purity.

Abstract: A method for purifying industrial waste water by direct oxidation of the organic pollutants in an electrochemical cell the anode of which contains, in its active part or in any intermediate layer present, neither noble metals in any form nor PbO.sub.2 nor graphite, but instead comprises in this part exclusively SnO.sub.2 which is doped with F, Cl, Sb, Mo, W, Nb, Ta or with a mixture of at least two of these elements. The anode has an oxygen overvoltage which is higher than that of a PbO.sub.2 comparison anode and reaches the value of at least 1.85 V at a current density of 0.1 mA/cm.sup.2 in 1 normal H.sub.2 SO.sub.4 under a pressure of 1 bar at a temperature of 20.degree. C. in the presence of a Pt counterelectrode.