Determination of H2O/H2 system exchange current densities on cycled hydride electrodes from overswitch potential jump at low and high charge/discharge rates

This research paper describes a simplified and quick method for determining the exchange current densities of the H2O/H2 system on powder composite electrodes made of hydrogen storage intermetallics. The method is based on the hydrogen storage electrode potential jump upon its gal-vanostatic overswitching from the cathodic to the anodic direction for low-and high charge/discharge rates. Indeed, research findings indicate that the discharge rate/ex-change current density quotient depends either linearly or exponentially on the potential jump for low-and high-charge/discharge rates. This study also defines the applicability ranges for both types of dependencies with the best accuracy for calculating exchange currents (relative experimental error <= 5%) corresponding to potential jumps of up to 0.037 V (discharge rates of up to 0.2C) and 0.08-0.20 V (discharge rates over 0.3C). Furthermore, this study presents other instances of determining exchange currents versus cycling determination for different intermetallics and discusses the effect of the hydride