Abstract: A positive active material for electric primary cells, such as are used in electronic watches, is formed from a powder composed at least partially of grains having cores of silver peroxide completely surrounded by a layer of monovalent silver oxide and covered with a thin surface layer of metallic silver. The remainder of the powder, if any, comprises monovalent silver oxide grains, also covered with a thin surface layer of metallic silver. A process for making the material includes adding a reducing agent such as hydrazine to a powder having grains of less than 50 microns in diameter of essentially pure silver peroxide and reducing the silver peroxide to the point at which a thin layer of metallic silver forms on the surface of each powder grain. This point can be detected by a substantial reduction in electrical resistivity of the powder and occurs when approximately one-half of the original powder remains as silver peroxide.

Abstract: Novel double chromate compositions having the general formula:MM'(CrO.sub.4).sub.2,wherein M and M' are silver and bismuth, respectively. Methods of making AgBi (CrO.sub.4).sub.2 are characterized by reacting silver dichromate with a bismuth salt to provide equal numbers of silver and bismuth atoms. These double chromate compositions have particular utility in batteries as active positive material. Due to the steadiness of discharge voltage and duration of discharge of batteries employing these double chromate compositions, such batteries are especially adapted for use in clocks and in cardiostimulators or pacemakers.BACKGROUND OF THE INVENTIONThis invention relates to a new chemical composition, and more particularly to a double chromate having the formula MM' (CrO.sub.4).sub.2 where M and M' represent metals, to methods of making it, and to its use as a positive active material in batteries.From the disclosure of French Pat. No.

Abstract: A method for precharging the negative electrode of a nickel-cadmium alkaline storage cell whose electrodes are assembled in an at least partially discharged state, wherein before the first charge of the cell, a calculated quantity of a material is introduced in the cell, such material being irreversibly oxidizable in an alkaline medium at a potential such that it is anodically oxidized before nickel hydroxide without evolving any gas, then the cell is charged in the normal way. The material preferably is an organic material of the general formula C.sub.x H.sub.y O.sub.z ; most preferably where x=n, y=2n+2, and z=1, with n less than 4. This particular class of materials comprises the three saturated mono-alcohols: methanol, ethanol and propanol.

Abstract: A high specific energy electric cell having a lithium negative active material, an electrolyte solution of which the solvent is an aprotic liquid, and the positive active material is a derivative of divalent lead oxide, PbO. The lead oxide derivation is a compound of said PbO and an oxide selected from the group comprising the oxides of bismuth, Bi.sub.2 O.sub.3, antimony, Sb.sub.2 O.sub.3, and tin, SnO.sub.2.

Abstract: An arrangement for sealing a button-type electric cell. Such a cell comprises a metal cup which contains a first electrode, and a metal cap which forms a cover to the cup and which contains a second electrode of opposite polarity. The rim of the cup is turned down over a seal disposed on the rim of the cap. A metal ring which has a cylindrical portion in contact with the inner face of the cylindrical wall of the cup, an intermediate portion which has a stair-case or an oblique cross-section and an annular portion which is orthogonal to the cylindrical portion is disposed in the cup, these latter two portions making it possible to compress the seal against the cylindrical wall of the cup.

Abstract: The invention relates to button type electric cells, i.e., cells comprising two cups containing, respectively, positive and negative active materials, fitted into each other and insulated from each other by a seal. The positive cup contains at least one compartment situated between it and the positive material and delimited on the positive material side by a perforated sheet; the compartment is filled with electrolyte when the active materials are in the state where they take up the greatest volume. Particularly applicable to lithium cells whose positive material is cupric oxide, lead oxide or red lead.

Abstract: Electrolytes for use in lithium primary cells are made from a mixture of three organic solvents and an alkaline solute. The first solvent is chosen to have a dielectric constant greater than 35 (e.g. propylene carbonate), the second solvent is a linear polyether with its ether functional groups in the .gamma. position (e.g. 1-2 dimethoxyethane) and the third solvent has a high solvation power for dissolving large quantities of the alkaline salt (e.g. 1-3 dioxolane). The solvents are so chosen that the conductivity maxima of the electrolytes that would be obtained by mixing the solvents in pairs are higher than the conductivity maxima of the electrolytes that would be obtained by using each of the solvents on its own. The positive electrode cell using the electrolyte may be cupric oxide or ferrous disulphide.

Abstract: A cylindrical electric cell which includes at least one positive electrode, at least one negative electrode disposed coaxially therewith and a device for maintaining the distance between these electrodes during discharge. In accordance with the invention, said device is constituted by the combination of a cylinder constituted by practically inextensible wires braided helically and by a spring which maintains this braid resiliently applied against the innermost or the outermost electrode of the electric cell.

Abstract: The invention relates to a negative electrode for an alkaline electrolyte electric cell. The main electrode material is nickel lanthanide and is characterized by the fact that it also includes a mercury compound. It is applicable to secondary electric cells, in particular of the nickel- or silver-hydrogen type. Cells embodying such negative electrodes exhibit improved capacity irrespective of temperature and electrolyte concentration conditions as compared with like cells in which the mercury compound is not used with the nickel lanthanide.

Abstract: Method and apparatus for charging storage batteries in which the charging rate is varied as a function of temperature are disclosed. The battery temperature and ambient temperature are sensed and compared. When the battery temperature is less than the ambient temperature plus a first temperature difference, a first charging rate is provided; when the battery temperature is greater than the ambient temperature plus the first temperature difference but less than the ambient temperature plus a second temperature difference which is greater than the first temperature difference, an intermediate charging rate is provided which varies with the comparison of the battery and ambient temperatures between the first charging rate and a second charging rate which is less than the first charging rate; and when the battery temperature is greater than the ambient temperature plus the second temperature difference, the second charging voltage is provided.

Abstract: A positive active material for electric primary cells, such as are used in electronic watches, is formed from a powder composed at least partially of grains having cores of silver peroxide completely surrounded by a layer of monovalent silver oxide and covered with a thin surface layer of metallic silver. The remainder of the powder, if any, comprises monovalent silver oxide grains, also covered with a thin surface layer of metallic silver. A process for making the material includes adding a reducing agent such as hydrazine to a powder having grains of less than 50 microns in diameter of essentially pure silver peroxide and reducing the silver peroxide to the point at which a thin layer of metallic silver forms on the surface of each powder grain. This point can be detected by a substantial reduction in electrical resistivity of the powder and occurs when approximately one-half of the original powder remains as silver peroxide.

Abstract: The invention relates to a casing of an electric cell and to a method of manufacturing the cell. The casing is fitted with a vent. The vent consists of a tongue formed in a metal portion of the casing whose inner surface is in contact with a seal; the non-detached tongue in the wall is turned towards the enclosed volume of the casing. In the case of internal overpressure, the seal is deformed and allows the interior of the electric cell to communicate with the exterior. Application to alkaline electrolyte cells.

Abstract: High energy density electric cells have lithium as the negative active material, a silver salt or a silver oxide as the positive material and a solution comprising one solute and at least two solvents as the electrolyte. According to the invention, the first solvent is chosen from the group of esters and the second is chosen from the group formed by benzene and its substituted derivatives.

Abstract: The invention relates to a positive active material for primary batteries having high energy density and constituted by a metal salt whose cation is monovalent silver and whose complex anion is composed of a central atom and ligands, for example a ferrocyanide or a ferricyanide. According to the invention, the ligands are at least partly constituted by monovalent anions. Application is to lithium primary batteries of the so-called button type or other conventional constructions useful particularly as energy sources for watches or heart stimulators or pacemakers wherein essential requirements are substantially uniform discharge voltage from inception of use to exhaustion and relatively long life.

Abstract: A storage cell rack, particularly for use with storage batteries of large capacity, comprises two insulative end plates interconnected by at least two insulative longerons which are fastened to the plates and which are provided with storage cell supporting hollows into which projecting studs from the cell are receivable. The assembly of end plates and longerons rests on a stand comprising two metal bars which extend parallel to the longerons, each bar having its ends upturned to constitute uprights which are fastened to respective ones of the end plates.

Abstract: An electrochemical cell that has a compact block formed by an assembly of first and second electrodes of opposite polarity separated by separator means. The block is housed in a container having a base and a cover. The rim of the container is turned down over the periphery of the cover to seal off the container contents. The borders of the first electrode project from opposite ends of the block and bear against the base and the cover. The invention is particularly applicable to a cylindrical cell having a spirally wound electrode block.

Abstract: A centrally-activated deferred-action silver-zinc battery has a central well defined by a stack of electrodes and separators each having a central hole. Isolating washers are placed around the central holes of each metal sheet and include recesses which provide curved channels for conveying electrolyte from the well towards the electrodes. The restricted cross-section and extended length of these channels ensure a greater electrical resistance to leakage currents which flow between couples via the electrolyte during activation. Pyrotechnic means are provided to activate the battery by rupturing a fragible partition and rapidly forcing electrolyte from an isolated compartment via the rupture in the partition into the well and from thence via the curved channels to spaces provided between electrodes of opposite polarity.

Abstract: The invention relates to a discharge indicator of an electrochemical generator such as a cell or battery comprising a consumable negative electrode basically containing powdered metal, for example, zinc. The said indicator is constituted by an enclosure containing a substance which can be seen from the outside of the battery and having an appearance which changes on coming into contact with the electrolyte, the said enclosure being closed by a metal plate arranged within the negative electrode and which is made of a material chosen from among zinc, zinc alloys, zinc amalgams. Application of the indicator is to air depolarization cells.

Abstract: Method for manufacturing pure silver chromate in which a soluble chromate is made to react with a silver salt in a bichromate medium. The bichromate medium stabilizes the pH and makes it possible to operate in a concentrated medium. The pure product obtained may be used more particularly as a positive active substance in an electrochemical generator having a non-aqueous electrolyte, for it enables avoidance of losses in capacity during idle and storage periods of the generator.

Abstract: The invention relates to electric cells which may comprise, for example, two trough-shaped elementary units mounted in a casing, each elementary unit comprising a relatively concavo-convex or trough-shaped positive electrode of compressed, plastified or sintered material, tightly sandwiched between two thin concavo-convex trough-shaped negative electrode parts obtained by folding a single electrode sheet around the positive electrode. Application of the invention is non-exclusively to alkaline storage cells.