Varta Batterie Aktiengesellschaft

Varta Batterie Aktiengellschaft

Frank Lichtenberg

Uwe Kohler

Klaus Kleinsorgen

Gunter Hofmann

Christoph Klaus

Alexander Bouvier

Andreas Folzer

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

To provide an improved high-temperature cycle lifetime, an alloy for use as active material for the negative electrode of an alkaline, rechargeable nickel-metal hydride battery has the composition

Alloys for use as active material for the negative electrode of an

The positive electrode of a Ni/metal hydride accumulator is formed from a mass mixture of Ni(OH).sub.2 and an oxidation-resistant graphite. The stable graphite is notable for a high degree of crystallinity and a low ash content. In conventional Ni/metal hydride accumulators, cobalt compounds play an essential part in developing a conductive matrix within their positive nickel hydroxide electrodes, leading to reductive destruction of the matrix by severe high temperature short circuit testing. In contrast, the same accumulators, with positive electrodes produced according to the present invention, survive the test with only a temporary and slight decline in capacity.

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Zeiskam, Germany

Frank Lichtenberg