Varta Batterie Aktiengesellschaft

Varta Batterie Aktiengesellshaft

Varta Batterie Aktiengellschaft

Uwe Kohler

Klaus Kleinsorgen

Alexander Bouvier

Andreas Folzer

Frank Lichtenberg

Gerhard Simon

Gunter Hofmann

Dietrich Sprengel

Christoph Klaus

Eberhard Niggemann

Detlev Hoge

Guangsen Chen

Jurgen Lindner

The invention relates to a process for recovering metals from used nickel/hydride storage batteries, in which storage battery scrap has been mechanically comminuted and divided into at least a coarse fraction and a fine fraction capable of being treated separately from one another. The process comprises the steps of digesting and dissolving the fine fraction with a mixture of sulfuric acid and hydrogen peroxide, performing a double sulfate precipitation of the rare earths by raising the pH, performing a precipitation of the iron and of the aluminum by further raising the pH, performing a solvent extraction of other metals to separate nickel and cobalt which remain in the aqueous phase from the other metals which are extracted into the organic phase. Optionally, the nickel and the cobalt can be separated from each other and, if desired, the mixed-metal rare earth component which has been recovered can be melted together with cobalt and nickel alloy for the fabrication of new batteries.

Process for the recovery of metals from used nickel/metal/rare earth

In the recycling of used nickel/metal hydride storage batteries, the battery scrap is dissolved in sulphuric acid after mechanical separation of the coarse constituents by magnetic and air separation. A solvent extraction is performed with the digestion solution, from which the rare earths (from the hydrogen-storage alloys in the negative electrodes) and iron and aluminum have been selected by precipitation, under conditions pH, choice of solvent, volumetric ratio of the phases) which are such that the aqueous phase contains nickel and cobalt in the same atomic ratio as that in which they were present in the scrap. This makes possible a joint recovery by simultaneous electrolysis, in which process the deposition product forms a master alloy which can be used, together with the precipitated rare earths which have been electrometallurgically reprocessed as misch metal, for the production of fresh hydrogen-storage alloys.

Process for the recovery of metals from used nickel/metal hydride

A Ni/Cd or Ni/hydride storage battery of the button cell type has a positive electrode tablet based on a nickel hydroxide powder having an active mass comprised of spherical particles with a high pycnometric density (d&gt;3.5 g/cm.sup.3). In contrast to conventional nickel hydroxide powders having irregular particles, a better space utilization is achieved during dry pressing due to a narrow particle-size distribution having a maximum in a range of from 5 to 20 .mu.m, and due to the rounded particle surfaces. The specific volumetric capacity of the resulting button cell electrode is consequently approximately 25% higher than that of a conventional positive button cell electrode. A microporous separator having pore sizes smaller than the mean diameter of the spherical particles prevents the danger of short circuits.

Gastight, sealed alkaline storage battery in the form of a button cell

As an active material for its negative electrode, a hydrogen storage alloy for a Ni/H battery has the composition

Alkaline metal oxide/metal hydride battery

A multicell storage battery, especially of the nickel/hydride type, is provided with pressure safeties for protection against high internal pressures. The pressure safeties respond at a preassigned critical pressure, causing mechanical changes in shape or through destruction which can be optically or electrically monitored. For example, a hinged lid is caused to swing up responsive to a rupture disk, interrupting a light beam. Alternatively, a rupture disk is coated with a conducting enamel and is connected by lead wires to form an electrical circuit which is interrupted responsive to damage of the enamel layer (e.g., responsive to bursting of the membrane).

Multicell storage battery

A gastight, sealed metal oxide/metal hydride storage battery, in particular, a nickel/metal hydride button cell, includes an auxiliary electrode with an active material composed of the same hydrogen storage alloy as that of the negative electrode with which the auxiliary electrode is electrically associated. As a result, the auxiliary electrode can maintain both oxygen consumption as well as hydrogen consumption (in the event of overcharging or polarity reversal of the cell). High gas consumption rates in the event of overcharging and polarity reversal are achieved with a strongly hydrophobic adjustment of the auxiliary electrode and a relatively weakly hydrophobic or hydrophilic adjustment of the negative electrode (by means of hydrophobic or hydrophilic binder additions, respectively), and by adding a highly conductive metal powder (Cu or Ni) to the mass of the negative electrode. Also achieved is a good discharge capacity, even at high currents of up to 2 CA.

Gastight, sealed metal oxide/metal hydride storage battery

A gas-tight nickel/hydride battery with a high oxygen consumption rate and a correspondingly low internal pressure has a stacked arrangement of positive and negative electrodes wherein the negative electrodes are divided in two with a coarse supporting framework as a space between the resulting partial electrodes. Gas impermeable microporous separators deflect the oxygen stream emerging from the positive electrodes to faces of the negative partial electrodes. The spacer provides an inner space with walls defining an enlarged area for reducing the deflected oxygen stream. Because the micropores are completely filled with electrolyte due to their capillary activity, the microporous separators also permit the construction of nickel/hydride batteries with cell heights which could not otherwise be achieved in alkaline batteries with nonwoven fabric separators.

Gas-tight sealed nickel/hydride battery

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.

Growing community of inventors

Kelkheim, Germany

Uwe Kohler