APPLICATION OF THE ELECTROCHEMICAL EXTRACTION METHOD TO THE STUDY OF A METAL HYDRIDE ELECTRODE -HYDROGEN SYSTEM

摘要

Information about using the electrochemical extraction method for studying the processes of hydrogen transport in hydrogen-absorbing alloys is absent. By using this method, the kinetics of extraction of hydrogen from electrodes made of the alloy MmNi_(3.5)(CoMnAl)_(1.5) was investigated. Time dependencies of the extraction current for different degrees of saturation of the electrode by hydrogen have the appearance typical of diffusion-controlled processes. By integrating the experimental extraction curves, the quantity of electricity spent on the ionization of hydrogen absorbed was evaluated, and then the total amount of hydrogen extracted was calculated. The ionization process is controlled by hydrogen diffusion in the solid phase; the kinetic parameters of the process were calculated. The change of the type of the time dependence of the extraction current with increasing degree of saturation of the electrode by hydrogen is explained by both a change in the character of hydrogen distribution in the sample and the possibility of transformation of the α phase into the α+β phase as the atomic ratio [H]/[alloy] rises.