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 Ml(NiCoAl) hydrogen storage alloys, including the high rate dischargeability, exchange current density I , limiting current density I , 5 0 L and diffusion of hydrogen in the hydride, by means of linear polarization, anodic polarization, cathodic polarization, and electrochemical impedance spectroscopy, was studied in detail. The results show that high rate dischargeability, the exchange current density i , and 0 limiting current density I increase, and the anodic and cathodic polarization decrease with the increase in concentration of KOH. The size L of a semicircle of electrochemical impedance spectroscopy decreased with increase in concentration of KOH, which indicates that the diffusion coefficient of hydrogen increases. Within the range of the experimentation, it can be concluded that the higher the concentration of KOH, the better the electrochemical properties of Ml(NiCoAl) hydrogen storage alloys.  1999 Published by Elsevier Science S.A. 5 All rights reserved.