Surface treatment of a LaNi5-type metal-hydride electrode with an alkaline solution dissolving cobalt(II) hydroxide

被引：30

作者：

Kuriyama, N ^{[1
]}

Sakai, T ^{[1
]}

Miyamura, H ^{[1
]}

Tanaka, H ^{[1
]}

Uehara, I ^{[1
]}

Meli, F ^{[1
]}

Schlapbach, L ^{[1
]}

机构：

[1] UNIV FRIBOURG,INST PHYS,CH-1700 FRIBOURG,SWITZERLAND

来源：

JOURNAL OF ALLOYS AND COMPOUNDS | 1996年 / 238卷 / 1-2期

关键词：

metal hydride electrode; LaNi5; surface treatment; KOH treatment; XPS; EIS;

D O I：

10.1016/0925-8388(95)02192-2

中图分类号：

O64 [物理化学（理论化学）、化学物理学];

学科分类号：

070304 ; 081704 ;

摘要：

The effects of KOH aqueous solution saturated with Co(OH)(2) on LaNi4.7Al0.3 electrodes were studied using electrochemical impedance spectroscopy and X-ray photoelectron spectroscopy. The electrochemical activity of an LaNi4.7Al0.3 electrode was considerably improved by a treatment with Co(OH)(2)-KOH solution below the potential of -0.8 V (vs. Hg/HgO) after several cycles in pure KOH electrolyte. These electrodes exhibited higher metallic-nickel and lower lanthanum concentrations in the subsurface region of the alloy than those without any treatment. This metallic-nickel enrichment was concluded to be caused by oxidation of metallic lanthanum with water catalyzed by Co(OH)(4)(2-) ions followed by a dissolution of lanthanum hydroxide. In contrast, the electrode treated with the Co(OH)(2)-KOH solution without regulation of potential before cycling in KOH solution exhibited lower electrochemical activity and metallic-nickel concentration than that without any treatment. In this case, Co(OH)(4)(2-) ions were considered to act as an oxidant to the alloy.

引用

页码：128 / 140

页数：13

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