Varta Batterie Aktiengesellschaft

Gerhard Simon

Uwe Kohler

Klaus Kleinsorgen

Eckart Buder

Gunter Hofmann

Bernd Gnida

Hans-Jurgen Schwartz

In a metal oxide/hydrogen storage battery, preferably formed as a coiled cell or as a button cell, having a negative electrode, a positive electrode, and an intermediate separator, the oxidation-sensitive negative electrode is protected against diffusing oxygen by a metallic covering of the electrode's metal hydride particles, and the oxygen reduction necessary for gas-tight operation is transferred to an auxiliary electrode which is arranged outside of the ionic path between the positive and negative electrodes. Metals with high solubility for hydrogen, such as Pd, Ni and Cu, are suitable as the covering material. The auxiliary electrode is formed as a film based on a mixture of activated carbon, a PTFE binder and conducting graphite, and is either laminated onto the negative metal hydride electrode or is spatially separated from the main electrodes, depending upon the cell's overall construction.

Gas-tight, sealed metal oxide/hydrogen storage battery

An auxiliary electrode for improving the consumption of oxygen in a gas-tight, sealed alkaline secondary cell is comprised of a synthetic nonwoven fabric and a film rolled onto the fabric. The film is a PTFE-bound activated carbon, and the side of the nonwoven fabric receiving the film is first impregnated with an aqueous cellulose ether mixture to develop a three layer structure including a highly porous, hydrophobic layer made of the nonwoven material, left in its original state and facing the electrolyte or a gas supply, a hydrophilic impregnated layer, and a catalytically active hydrophobic consumption layer electrically connected with the cell's negative electrode and constituting the preferred location for oxygen reduction, at the resulting hydrophobic/hydrophilic transition layer. The auxiliary electrode is located outside of the ionic path between electrodes of opposite polarity, but in electron-conducting contact with the negative electrode, excluding the auxiliary electrode from unwanted interaction with the NO.sub.2 /NH.sub.3 --auto-discharge path.

Gas-tight, sealed alkaline secondary cell

Overcharge protection, and especially the chargeability of a sealed Ni/Cd battery with high currents (up to 1 CA) is improved by rolling a carbon-containing powdered material into the surface of the negative electrode, which material catalyzes the reduction of oxygen. Wetting of the electrode with a 'Tylose' dispersion prior to application of the powder (by powdering, vibration or in an agitator) improves the adhesion of the powder. The cadmium electrode thus prepared combines in itself the functions of a negative principal electrode and of an auxiliary oxygen electrode.

Sealed nickel-cadmium battery

The electrodes and separators are assembled into a plate package, which is slipped over a post extending upward from the cell housing bottom. Pole lead-through is provided in the lid, the lead-through includes a rivet and a sealing ring. The edges of the housing bottom and the tip of the post are welded to the lid to close the cell.

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Kelkheim, Germany

Gerhard Simon