Effects of pretreatment on the activation behavior of Zr(V0.25Ni0.75)2 metal hydride electrodes in alkaline solution

doi:10.1016/0925-8388(94)91082-0

Journal of Alloys and Compounds

Volume 209, Issues 1–2, July 1994, Pages 99-105

https://doi.org/10.1016/0925-8388(94)91082-0 Get rights and content

Abstract

Metal hydrides used as negative electrodes in rechargeable batteries are covered with surface oxides during preparation of the electrode. They inhibit or slow down the absorption rate of hydrogen and have to be dissolved or made conductive in an activation process. In order to minimize the activation cycles we have investigated the influence of the pretreatments of the metal hydride powder Zr(V_0.25Ni_0.75)₂ with KOH and fluoride-containing solutions on the surface composition of the alloy grains by means of X-ray photoelectron spectroscopy. The study establishes the relationship between the surface composition of the hydrogen-storing material and the electrode performance, e.g. discharge capacity and high-rate dischargeability. The speed of activation increased with increasing nickel content in the top surface layers (30 Å) of the metal hydride.

References (17)

F. Meli et al.
J. Alloys Comp.
(1992)
S. Wakao et al.
J. Less-Common Met.
(1991)
C. Iwakura et al.
J. Power Sources
(1992)
M. Matsuoka et al.
J. Alloys Comp.
(1993)
M. Matsuoka et al.
Electrochim. Acta
(1993)
A. Züttel et al.
J. Alloys Comp.
(1993)
A. Züttel et al.
J. Alloys Comp.
(1994)
F.-J. Liu et al.
J. Alloys Comp.
(1992)

There are more references available in the full text version of this article.

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Effects of pretreatment on the activation behavior of Zr(V0.25Ni0.75)2 metal hydride electrodes in alkaline solution

Abstract

J. Alloys Comp.

J. Less-Common Met.

J. Power Sources

J. Alloys Comp.

Electrochim. Acta

J. Alloys Comp.

J. Alloys Comp.

J. Alloys Comp.

Effects of pretreatment on the activation behavior of Zr(V_0.25Ni_0.75)₂ metal hydride electrodes in alkaline solution