Systematic B-metal substitution in CaNi5

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Abstract

The aim of this work has been to study the effect of B metal substitutions in CaNi5 (AB(5)) which is known to suffer from poor cycling stability as a hydride electrode material. Systematic monosubstitutions of nickel with the most common other B metals (i.e. Al, Cr, Mn, Fe, Co, Cu, Zn and Sn) and Mg were performed. The overall composition was in all cases CaNi5-xMx (x=0.5 or 1) where M is the substituting element. The alloys were prepared by mechanical alloying. The hydrogen storage capacity was measured electrochemically ranging from 39 to 390 mAh/g, but none of the substitutions increased the cycling stability to any significant extend compared to pure CaNi5. X-ray diffraction patterns of the alloys revealed that only in a few cases the hexagonal CaCu5 structure of a true AB(5) alloy was preserved. In most cases diffraction patterns matching Ca2Ni7, CaNi3 or CaNi2 were seen. It can be concluded that CaNi5 is much less tolerant towards B-metal substitution than LaNi5. This fact makes it less possible that the problem with cycling stability of Ca-based hydride electrodes can be solved by substitutions. (C) 1999 Elsevier Science S.A. All rights reserved.
Original languageEnglish
JournalJournal of Alloys and Compounds
Volume293-295
Pages (from-to)185-189
ISSN0925-8388
DOIs
Publication statusPublished - 1999
Event6th International Symposium on Metal-Hydrogen Systems: Fundamentals and Applications - Hangzhou, China
Duration: 4 Oct 19989 Oct 1998
Conference number: 6

Conference

Conference6th International Symposium on Metal-Hydrogen Systems
Number6
CountryChina
CityHangzhou
Period04/10/199809/10/1998

Keywords

  • Hydrides
  • CaNi5
  • Electrodes
  • Substitution
  • Hydrogen storage

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