Electrochemical and structural characteristics of TiV2.1Ni0.3 surface-modified by ball-milling with MgNi

V-based TiV2.1Ni0.3 alloy with high hydrogen storage capacity was surface-modified by ball-milling with amorphous MgNi alloy prepared by mechanical alloying. In charge-discharge cycle measurements, the decrease in discharge capacity for the prepared TiV2.1Ni0.3-MgNi composites was effectively suppressed in comparison with the TiV2.1Ni0.3 alloy. In particular, ball-milling for 3 h is the most effective in the present study. This was explained by surface analyses with EPMA mapping and X-ray photoelectron spectroscopy (XPS). Changes in the EPMA maps, XPS spectra and depth profiles of the surface alloy components suggested that the ball-milling caused the mutual diffusion between Mg and a little of the Ni components in the MgNi alloy and Ti and V components in the TiV2.1Ni0.3 alloy at the interface between both alloys. In addition, stable time course of rest potential for the TiV2.1Ni0.3-MgNi composite electrodes immersed in 6 M KOH solution also showed the effectiveness of the surface modification with ball-milling. (C) 2000 Elsevier Science S.A. All rights reserved.