Electrocatalytic Hydride-Forming Compounds for rechargeable batteries

Authors

  • Dr. Peter H. L. Notten,

    1. Philips Research Laboratories P.O. Box 80000, NL-5600 JA Eindhoven (The Netherlands)
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    • Was born in 1952 in The Netherlands and joined Philips Research Laboratories in 1975. While working at these laboratories on the electrochemistry of the etching of III–V semiconductors he received his Ph. D. from the Eindhoven University of Technology in 1989. A book on this subject was completed recently in collaboration with two co-authors. Since 1987 his research activities have focused on small rechargeable batteries and in particular on the electrochemistry of hydride-forming electrode materials.

  • Dr. Robert E. F. Einerhand

    1. Philips Research Laboratories P.O. Box 80000, NL-5600 JA Eindhoven (The Netherlands)
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    • Graduated from the Vrije Universiteit of Amsterdam in 1984, and received his Ph. D. from the Eindhoven University of Technology in 1989. His doctoral research involved the electrochemistry of zinc in aqueous alkaline solutions, with special attention paid to the application of zinc in secondary batteries for electric vehicle propulsion purposes. In 1989 he joined Philips Research Laboratories as a research scientist in the group Interfacial Chemistry. With Philips his main research topic is the electrochemical behavior of hydride-forming intermetallic compounds which can be used in alkaline secondary batteries.


Abstract

A New class of highly electroactive hydride-forming compounds is described as well as simple metallurgical methods for producing these materials. The new type of metal alloys consist of two different crystallographic phases. The bulk phase is responsible for hydrogen storage and is formed by the stable multicomponent “standard alloy” of the AB5 type. The second phase homogeneously decorates the surface of the bulk phase and ensures a high electrocatalytic activity. In composing this second phase no precious metals are required, but carefully selected combinations of transition metals can be used. Very high overall exchange currents and discharge efficiencies are obtained, even at low temperature. Cycle life and storage capacities are comparable with the values found for the standard alloy. Substituting small amounts of B-metals with highly electrocatalytic elements was also found to be effective in improving the electroactivity of AB5 compounds. However, a drawback of this method is that significant improvements are obtained only when precious metals are incorporated. Double-phase materials must therefore be considered as more serious candidates for use in future nickel/metal-hydride batteries with high charge/discharge capability.

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