On the nature of the electrochemical cycling stability of non-stoichiometric LaNi5-based hydride-forming compounds Part I. crystallography and electrochemistry

A Structural Study of the Homogeneity Domain of LaNi5

“…This excludes the possibility of nickel being substituted solely by lanthanum since this would result in a significant increase of electron density at these sites and thus in an inferior fit to the data. On the other hand, refinements under the assumption of Ni vacancies lead to agreement factors slightly, but not significantly, better than those of the stoichiometric model, but the results were at variance with the composition as measured by EPMA (LaNi 4.88 (2) ).…”

“…For substoichiometric LaNi 5+x the microprobe analysis of the segregated La 20 Ni 80 alloy indicates the lower phase limit to be LaNi 4.88 (2) . The same limit has been found for the CaCu 5 -type phase in the Y-Co system (17).…”

“…A most important parameter is the compositional ratio B/A in as much as it controls properties such as plateau pressure and cycle life (2,3). For binary LaNi 5+x past investigations have suggested (4) that the phase extends over the compositional range À0.15rxr0.40 at a temperature of 12001C.…”

Nanocrystalline Hydrogen Storage Alloys Formed by Mechanical Alloying

“…These intermetallic compounds belong to the most promising electrode materials for application in rechargeable Ni-MH x batteries because of the rapid and reversible storage of large quantities of hydrogen [1][2][3]. Traditionally the metal hydride materials have been prepared by arc melting the elements, followed by a long annealing to homogenize the alloy.…”

“…Among the hydrogen forming compounds, AB 5 -based intermetallics have recently proven to be very attractive as negative electrode materials, too [3,4]. The properties of these materials can also be modified substantially by alloying, to obtain the desired storage characteristics, e.g.…”