Method of forming a nickel layer on the cathode casing for a zinc-air cell

A method of forming a metal layer consisting essentially of nickel on a metal substrate for a cathode casing of a zinc/air button cell, comprising:

• (a) forming at least a portion of a cathode casing for a zinc/air button cell, wherein said cathode casing comprises a metal substrate comprising cold rolled steel or stainless steel,
• (b) plating a layer consisting essentially of nickel onto said metal substrate so that said nickel covers at least a terminal contact area on the outside of said cathode casing,
• (c) heating the metal substrate with said layer of nickel thereon in a substantially inert atmosphere at a temperature between about 860° F. and 135° F. for between about 2 and 12 minutes to reduce the surface hardness of said nickel layer to a level of between about 2 and 7 giga pascal as measured at a depth of about 100 nanometers from the surface thereof, thereby improving the electrical contact of said cathode casing with a hearing aid device to be powered by the zinc/air cell,
• (d) electrically connecting said terminal contact area on the outside of said cathode casing to a hearing aid.