Influence of concentration of KOH solution containing 0.02 M borohydride on the kinetic properties of hydrogen storage alloys

In this paper the effect of concentration of KOH solution containing 0.02, M borohydride on the electrochemical properties of MI(NiCoAl)(5) hydrogen s torage alloys, including the high rate dischargeability,exchange current de nsity I-o, limiting current density I-L and diffusion of hydrogen in the hy dride, by means of Linear polarization, anodic polarization, cathodic polar ization, and electrochemical impedance spectroscopy, was studied in detail. The results show that high rate dischargeability, the exchange current den sity i(o), and limiting current density I-L increase, and the anodic and ca thodic polarization decrease with the increase in concentration of KOH. The size of a semicircle of electrochemical impedance spectroscopy decreased w ith increase in concentration of KOH, which indicates that the diffusion co efficient of hydrogen increases. Within the range of the experimentation, i t can be concluded that the higher the concentration of KOH, the better the electrochemical properties of ML(NiCoAl)(5) hydrogen storage alloys. (C) 1 999 Published by Elsevier Science S.A. All rights reserved.