Electrical Storage and Hydrogen Transfer between Electrodes of Palladium and Palladium Alloys

Abstract

ELECTRODES of palladium and palladium alloys can absorb large volumes of hydrogen. In general, the solid hydrides retain excellent electrical conductivity and are not severely embrittled or disrupted. For pure palladium, and for many alloys, the relationships between electrodo potential E (with respect to a hydrogen reference electrode in the same solution) and hydrogen content (written here. Fig. 1, as the ratio, H/Me, of hydrogen atoms to the total number of metal atoms) exhibit ‘plateau’ regions—over which α- and β-phase hydrides co-exist—where E is relatively invariant (E_α,β). Over such ‘plateau’ regions, hydrogen transfer should, in principle, occur at a constant rate when connexion is made between an alloy and palladium or between two alloys. However, polarization¹ would be expected to occur rapidly if the diffusion of hydrogen within the electrodes were not sufficiently fast for the concentration of hydrogen at the surfaces to be continuously representative of the ranges of H/Me corresponding to the plateaux. The following experiments serve to illustrate what may be observed in practice.