The effect of particle size on the electrode performance of Ti-V-based hydrogen storage alloys

The effect of particle size ranging from 100 mesh to below 500 mesh on the electrochemical properties of Ti0.8Zr0.2V2.7Mn0.5Cr0.8Nix (x = 0.75, 1.75) hydrogen storage alloy electrodes was investigated. SEM observation on the surface of the alloy electrodes after charge/discharge cycles revealed that the abilities of anti-pulverization and anti-corrosion of the x = 0.75 alloy were much lower than those of the x = 1.75 alloy. For both of the two alloys, the electrode performance is affected markedly by the particle size. With the increase of the initial particle size, the initial discharge capacity of the alloy electrode decreases and the pulverization of the alloy particles aggravates, especially for the particles of the x = 0.75 alloy with size larger than 400 mesh, the size of which was minimized obviously compared with their initial size. However, the maximum discharge capacity and the cycling stability almost do not correlate to the initial particle size but relate with their actual particle size. As the actual particle size decreases, the maximum discharge capacity increases and the cycling stability declines. (C) 2007 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.