Patent ID: 8444840

Claim:
A method for forming a coated casing for an electrochemical cell, comprising the steps of: providing an electrode casing comprising a metal substrate having an interior surface and an exterior surface, the substrate comprising a copper layer on the interior surface; plating a first metal layer with a plating solution on the interior surface and on the exterior surface of the substrate utilizing a first current density; and changing the first current density to a second different current density while the substrate of the electrode casing is in contact with the plating solution and plating a second metal layer on the first metal layer on the interior surface and on the first metal layer on the exterior surface, the second metal layer being adapted to be exposed to the atmosphere when the electrode casing is assembled in an electrochemical cell; wherein: the first metal layer has a ratio of copper from 50 to 70 weight percent, tin from 26 to 42 weight percent, and zinc from 3 to 9 weight percent, measured at a central portion of the exterior surface of the substrate of the electrode casing by SEM/EDS; and the second metal layer has a ratio of copper from 36 to 46 weight percent, tin from 42 to 57 weight percent and zinc from 6.5 to 9.5 weight percent, measured at a central portion of the exterior surface of the substrate of the electrode casing by SEM/EDS.