A dilatometric study of nickel wire electrode electrochemically charged by hydrogen

The cathodic charging of nickel with hydrogen was studied with simultaneous measurements of dimensional variations within the solubility region. Relative dimensional changes as low as 3 X 10(-6) could be detected which makes this measuring combination sensitive and powerful in studying the behavior of metal hydrogen systems, particularly in the low hydrogen concentration region. The effect of current density, solution acidity and type of promoter on the extent of relative dimensional variations induced by the cathodic process is presented. Also, the process coulombic efficiency, i.e. the charge fraction converted into absorbed hydrogen atoms, is calculated and interpreted via the dimensional changes.