Hydrogen related peaks in Cu–LaNi 4.7Al 0.3

Abstract

In this work, the effect of Ni substitution by Cu in the LaNi 4.7Al 0.3 hydride-forming alloy was studied in order to apply it to the negative electrodes of Ni–MH batteries. SEM, EDS and X-ray diffraction techniques were used to analyze the microstructure, composition and crystalline structure of the samples. A maximum electrochemical discharge capacity of 130 mAh/g was obtained. Internal friction (IF) and shear modulus ( G) were measured by means of low frequency mechanical spectroscopy, between 100 and 450 K. In the electrochemical activated sample, two main IF peaks and typical relaxation steps in G showed up at 200 and 280 K. The first is ascribed to interactions between hydrides and H atoms in solid solution and dislocations, while the last one is attributed to the β ↔ α hydride phase transformation.