The structure and electrode properties of non-stoichiometric type C14 Laves alloy and the effect of surface modification

In this paper, the structure and electrode properties of non-stoichiometric A 1.2 B 2 type Laves alloy Ti 0.7 Zr 0.5 V 0.2 Mn 1.8 - x Ni x ( x = 0.4 , 0.8, 1.1, 1.4 and 1.7) were investigated systematically by electrochemical techniques, XRD and EDS, in terms of their discharge capacity, cycle life, and phase structure. The main phase is C14 Laves phase and the second one is TiNi cubic phase, except for alloy Ti 0.7 Zr 0.5 V 0.2 Mn 0.1 Ni 1.7 . The influence of surface modification including ball milling with Ni powders and amorphous MgNi powders was also investigated to examine the importance of Ni component for the electrode properties. To our knowledge, the main function of Ni component is to improve the surface electro-catalytic activity. The kinetic parameters were tested and the relation between the parameters and high-rate dischargeability was discussed. The nature of improvement of electrode performance is the improvement of the kinetic parameters, especially the high-rate discharge ability. The increased atmospheric temperature leads to the appearance of a two-discharge plateau, the nature of which was discussed. Three different measurement methods of diffusivity (electrochemical impedance spectroscopy, limiting current and discharge at constant current) were compared.