Patent ID: 7632605
Filing Date: 2009-12-15
Classification: H01M

Abstract:
1. An electrochemical battery cell comprising a positive electrode; a negative electrode comprising zinc; a separator disposed between the positive and negative electrode; an electrolyte comprising a solute and an aqueous alkaline solvent; and a cell housing containing the electrodes, separator and electrolyte; the housing comprising a metal positive electrode casing in contact with the positive electrode, a metal negative electrode casing in contact with the negative electrode and a seal member disposed between and electrically insulating the positive and negative casings for sealing the electrodes and electrolyte within the cell housing; wherein: the negative electrode casing is formed from a metal substrate substantially free of copper and having a first major surface, a second major surface and an edge surface around the perimeters of the major surfaces; the negative electrode casing has a shape with an exposed surface comprising at least portions of the first major, second major and edge surfaces; the negative electrode casing has a seal area for sealing engagement with the seal member and a current collector area for contacting the negative electrode; at least those portions of the exposed surface of the negative electrode casing in the seal area and the current collector area are coated with a first layer of an alloy comprising copper, tin and zinc and the relative amounts by weight of the copper, tin and zinc are from 55 to 85, from 9 to 30 and from 2.5 to 20, respectively; at least those portions of the exposed surface of the negative electrode casing in the seal area and the current collector area are coated with a second layer of an alloy comprising copper, tin and zinc over the first layer of an alloy comprising copper, tin and zinc; and a ratio of copper to tin in the second layer that is lower than a ratio of copper to tin in the first layer.