Electrochemical properties and characteristics of the fluorinated Zr0.9Ti0.1V0.2Mn0.6Ni1.3La0.05 electrode

Improvement of the initial activation characteristics and electrochemical reaction activity of the Laves-phase alloy surface are of basic importance for the application of hydriding alloy to Ni/MH batteries which exhibit larger discharge capacity than those of AB(5). The fluorination effects of the electrode made by Zr0.9Ti0.1V0.2Mn0.6Ni1.3La0.05 Laves phase alloy on the electrochemical properties and characteristics, especially on the initial charge-discharge capability and electrochemical reaction activity were investigated in terms of the electrochemical impedance and surface microstructures. The fluorination procedure employed to the La-incorporated Laves phase is significantly effective for improving initial activation characteristics. The Specific surface area of the fluorinated particles were increased by about 20 times larger than those of the untreated one from 0.27 to 5.31 m(2)/g which were contributed to the formation of La-fluoride, and also by the implantation of nickel over the particle surface. Fluorination treatment employed in this study for the La-incorporated Laves phase alloy was found effective for increasing the specific surface area and the surface charge acceptance during the initial charge process. (C) 1999 Elsevier Science S.A. All rights reserved.