P. R. Mallory Co.

Duracell International Inc.

Franciszek J Przybyla

Michael J Smith

Eleanor J Rossler

A silver oxide powder for use in the cathode of an alkaline silver oxide galvanic cell, being a mixture of at least 10% divalent silver oxide powder together with monovalent silver oxide powder, is produced by at least partially reducing the silver oxide powder mixture by reacting it with a surfactant, particularly an anionic surfactant and thereafter removing the reactant. The silver oxide powder displays a lower oxygen evolution rate when immersed in an alkaline electrolyte, and lower internal friction during powder flow under pressure when compared with a similar silver oxide mixture which is known not to have been so reacted.

Method of treating silver oxide powder and the product formed therefrom

A silver oxide powder for use in the cathode of an alkaline silver oxide galvanic cell, being a mixture of at least 10% divalent silver oxide powder together with monovalent silver oxide powder, is produced by at least partially reducing the silver oxide powder mixture by reacting it with a fatty acid or a fatty acid salt and thereafter removing the reactant. The silver oxide powder displays a lower oxygen evolution rate when immersed in an alkaline electrolyte, and lower internal friction during powder flow under pressure when compared with a similar silver oxide mixture which is known not to have been so reacted.

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.

Hydrogen evolution inhibitors for cells having zinc anodes

A gas-depolarizable galvanic cell is provided having restricted gas access to the cathode. The cell is generally a metal-air cell, and may particularly be a button cell suitable for use in electronic watches, hearing aids and the like. The restricted gas access to the cathode comes either by way of a very small aperture in the cell container, or in an additional barrier layer placed within the cell. The cross-sectional area of the gas passageway is less than the projected area of the gas passageway through the thickness of the container or additional barrier layer; and may be formed by piercing or punching but more particularly by exposing the container or the material of the additional barrier layer to a laser beam.

Metal-air depolarized cell having restricted gas passageway

A gas-depolarizable galvanic cell in which restricted gas and water vapor access to the gas-depolarizable cathode is provided by interposing a gas and moisture impermeable barrier in the gas communication path and carefully controlling the size of holes or openings in the barrier so as to restrict the gas flow rate past the barrier.

Metal-air depolarized cell with restricted water vapor access

A self sealing microporous membrane of utility especially in electrochemical cells of the gas-depolarized type comprising a microporous polymer membrane of a density range between about 0.7 and 1.9 grams per centimeter embodies a pressurized sealing zone of maximum density and zero porosity. Such pressurized zone is located to provide a seal against leakage of electrolyte.

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Mississauga, Canada

Franciszek J Przybyla