Method of forming an electrode casing for an alkaline electrochemical cell with reduced gassing

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 wherein from the exterior surface to the interior surface the substrate has a nickel layer, a stainless steel layer and a copper layer;
• plating a first metal layer with a plating solution on at least 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 electrode casing is in contact with the plating solution and plating a second metal layer that is adapted to be exposed to the atmosphere when the electrode casing is assembled in an electrochemical cell on the first layer;
• wherein:
• the first and second plated layers each comprise copper, tin and zinc;
• the first layer has a ratio of surface values according to XPS of 85 to 91 atomic percent copper, 6 to 11 atomic percent tin, and 2 to 6 atomic percent zinc;
• and
• the second layer has a ratio of surface values measured according to XPS of 73 to 84 atomic percent copper, 11 to 17 atomic percent tin, and 4 to 10 atomic percent zinc.

A method for forming an electrochemical cell, comprising the steps of:

• providing a first electrode casing comprising a metal substrate having an interior surface and an exterior surface;
• plating the interior surface and the exterior surface of the substrate of the first electrode casing with a copper-tin-zinc alloy utilizing a variable current density while the substrate is in contact with a plating solution thereby producing a plated substrate having a first layer and a second layer, and wherein a tin content increases from the first layer to the second layer;
• and
• forming an electrochemical cell comprising a first electrode in contact with the interior surface of the plated substrate of the first electrode casing and an aqueous alkaline electrolyte, wherein, prior to plating, the substrate of the first electrode casing has a copper layer on the interior surface;
• wherein:
• the current density is decreased during the plating such that the first 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 plated substrate by SEM/EDS,
• and the second 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 plated substrate by SEM/EDS.