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MM: Metall- und Materialphysik

MM 14: Hydrogen in Metals I

MM 14.2: Vortrag

Dienstag, 28. März 2006, 10:30–10:45, IFW D

New hydride electrodes for Ni-MH batteries on basis of Mg-Ni-Y metastable alloys — •Bogdan Khorkounov, Annett Gebert , Christine Mickel, Margitta Uhlemann, and Ludwig Schultz — IFW Dresden, PF 27 01 16, Dresden, Germany

This work aims at characterizing of novel Mg-Ni-Y amorphous and nanocrystalline alloys with view to their possible application as new hydride electrode materials in Ni-MH batteries. On the example of Mg63Ni30Y7, the alloying conditions were optimised so that alloys with an amorphous or a nanocrystalline-amorphous microstructure were obtained. On basis of these alloy powders, hydride electrodes were fabricated and their electrode characteristics under battery operation conditions were investigated. The alloys with mixed nanocrystalline-amorphous microstructure prepared under use of a SPEX shaker mill and more considerable fraction of nanocrystalls reveal a higher electrochemical activity for hydrogen reduction at cathodic potentials and a higher maximum discharge capacity (247 mAh/g) than the alloys with predominantly amorphous microstructure (216 mAh/g) obtained when using a Retsch planetary ball mill at lowered temperatures. The positive role of increasing Y and Ni concentration in the alloy was observed. The influence of surface modification by coating of the alloy particles by graphite or nickel on the electrodes stability and reactivity was studied in detail.