Abstract
The electrochemical behaviour of LaNi4Fe, LaNi4.5Mn0.5 and LaNi3.55Mn0.4Al0.3Co0.75 intermetallic compounds was investigated using chronopotentiometry, electrochemical impedance spectroscopy (EIS), constant potential discharge (CPD) and cyclic voltammetry (CV) techniques. The hydrogen diffusion coefficient was determined by EIS and CV. The obtained values by EIS were 2.7×10−10cm2s−1 for LaNi4Fe, 1.4×10−10cm2s−1 for LaNi4.5Mn0.5 and 2.7×10−10cm2s−1 for LaNi3.55Mn0.4Al0.3Co0.75. The obtained values by CV were 8.1×10−8cm2s−1 for LaNi4Fe, 2.5×10−7cm2s−1 for LaNi4.5Mn0.5 and 1.5×10−7cm2s−1 for LaNi3.55Mn0.4Al0.3Co0.75. The sphere radius of particles of alloys was estimated by CPD, the obtained values were 29μm for LaNi4Fe, 36μm for LaNi4.5Mn0.5 and 31μm for LaNi3.55Mn0.4Al0.3Co0.75. The exchange current densities of MH electrodes were estimated by EIS. The obtained values are between 11 and 15mAcm−2.