Electrical nickel-metall hydride accumulator with electrode of nickelhydroxide comprising eraphite.

摘要

In contrast to conventional Ni/metal hydride accumulators, in which cobalt compounds are essentially involved in the construction of a conductor skeleton within their positive nickel hydroxide electrodes, but which suffer a massive irreversible capacity drop (Curve 1) as a result of reductive breakdown of this skeleton by an intensified high-temperature storage test after 6 conditioning cycles, the same accumulator cells withstand the storage test with only a slight, temporary capacity drop if their positive electrodes are formed by a bulk mixture of Ni(OH)2 and an oxidation-resistant graphite (curve 2). The stable graphite is distinguished by a high degree of crystallinity (crystallite size > 200nm) and has a low ash content < 0.5%.