Reaction kinetics and X‐ray Absorption Spectroscopy Studies of Yttrium‐Containing Metal Hydride Electrodes

Abstract

This is a study of electrode degradation mechanisms and reaction kinetics of , ( x = 0.1, 0.2, and 0.3) and metal hydride electrodes. Alloy characterization included X‐ray diffraction, X‐ray absorption (XAS), hydrogen absorption in a Sieverts apparatus, and electrochemical cycling of alloy electrodes. The atomic volume of H was determined for two of the alloys. Electrochemical kinetic measurements were made using steady‐state galvanostatic measurements, galvanodynamic sweeep, and electrochemical impedance techniques. XAS was used to examine the degree of corrosion of the alloys with cycling. Alloying with Y decreased the corrosion rate. The results are consistent with corrosion inhibition by a Y‐containing passive film. The increase in the exchange current density of the hydrogen oxidation reaction with increasing depth of discharge was much greater on the Y‐containing alloys. This may be due to the dehydriding of the catalytic species on the surface of the metal hydride particles. © 1999 The Electrochemical Society. All rights reserved.