Electrochemical Properties and Dissolution Mechanism ofA2Ni7 Hydrides (A=Y, Gd, La–Sm)

The electrochemical behavior of hydride-forming A2B7 alloys(Y2Ni7, LaSmNi7, and Gd2Ni7) is investigated in KOH solution.The evolution of the material performance is shown to stronglydepend on the A elements. Electrochemical impedancespectroscopy (EIS), SEM observations, XRD, and Raman spectroscopysh...

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Published in:ChemElectroChem 2015-09, Vol.2 (9), p.1321-1330
Main Authors: Puga, Beatriz, Joiret, Suzanne, Vivier, Vincent, Charbonnier, Véronique, Guerrouj, Habiba, Zhang, Junxian, Monnier, Judith, Fariaut-Georges, Cécile, Latroche, Michel, Goubault, Lionel, Bernard, Patrick
Format: Article
Language:English
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Chemical Sciences
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Summary:The electrochemical behavior of hydride-forming A2B7 alloys(Y2Ni7, LaSmNi7, and Gd2Ni7) is investigated in KOH solution.The evolution of the material performance is shown to stronglydepend on the A elements. Electrochemical impedancespectroscopy (EIS), SEM observations, XRD, and Raman spectroscopyshowed that Y2Ni7 is mainly sensitive to calendar corrosionand decrepitation, whereas LaSmNi7 and Gd2Ni7 are sensitiveto the concomitant effect of both cycling and calendar corrosion. It is also shown that the capacity loss of Gd2Ni7 canbe ascribed to amorphization on cycling, which is not the casefor Y2Ni7. The formation of both an thin oxide film (a few tensof nanometers thick) at the material surface, measured by EIS,and the dissolution products formed during long-term immersion,analyzed by Raman spectroscopy, is in agreement withthe decrease in material activity evaluated by EIS during cyclingat different depths of charge.
ISSN:2196-0216
2196-0216
DOI:10.1002/celc.201500163