Process for forming a nickel foil with controlled and predetermined permeability to hydrogen

A process for forming a nickel foil having a controlled and predetermined hydrogen permeability, said process comprising the steps of

• (a) passing a nickel plating bath through a copper and gold cation-removing cation exchange resin, whereby there is provided a purified nickel plating bath free of copper and gold cations;
• (b) immersing a readily-corrodible nickel anode and a cathode in said purified bath comprising a selected concentration of an organic sulfonic acid;
• said cathode being suitable for electrodeposition of nickel thereon and being separable from an electrodeposited nickel layer;
• (c) electrodepositing a nickel layer having the thickness of a foil directly onto said cathode, while maintaining the cathode current density and bath temperature at selected values;
• and
• (d) separating the electrodeposited nickel layer from said cathode to provide a nickel foil;
• whereby said nickel foil has a controlled and predetermined hydrogen permeability.