Patent ID: 8921009

Claim:
A method for forming a fuel cell stack, comprising the steps of: a) providing a plurality of die-cut stainless steel sheets each having (i) a thickness of less than 0.2 mm, (ii) a first face, and (iii) an opposing second face; b) using an electromagnetic brush printing apparatus to electrostatically deliver a precursor layer having a uniform thickness of less than 0.3 mm onto a first face of the plurality of die-cut stainless steel sheets, wherein the precursor layer has particles having an average diameter of at least 25 microns and less than 125 microns, and having a one component substantially solid precursor formulation including: i) a solid bisphenol A based epoxy in an amount greater than 80 percent by weight of the composition; ii) a solid epoxy carboxy-terminated butyl nitrile (epoxy-CTBN) adduct, having an epoxide equivalent weight of 1500 g/mole, the solid epoxy-CTBN being present in an amount of between 1:5 to 1:6 parts by weight relative to the solid bisphenol A based epoxy; iii) a dicyanamide curing agent in are amount of e than 4 percent by weight of the composition; and iv) at least one pigment in an amount of less than 2.5% by weight of the precursor layer; (c) physically transforming the particles of the precursor layer to form a precursor layer film that is tack-free while on a respective die-cut stainless steel sheet to which it has been delivered and thereby forming at least a temporary adhesive bond between the precursor layer and the die-cut stainless steel sheet; (d) heating each precursor layer film to a temperature above a cross-linking activation temperature for cross-linking the solid bisphenol A based epoxy and the solid epoxy-CTBN adduct to define a cross-linked reaction product material layer; (e) forming a stack of at least 200 of the die-cut stainless steel sheets having the cross-linked reaction product material layer thereon by stacking consecutive sheets so that respective first faces of the sheets oppose respective second faces of the sheets with a respective cross-linked reaction product material layer therebetween, and thereby defining an outermost cross-linked reaction product material layer; (f) sandwiching a plurality of membrane electrode assemblies, each including an anode, a cathode, and a membrane between the anode and the cathode, between the plurality of die-cut stainless steel sheets; (g) bonding the consecutive sheets to each other while maintaining a gap between a portion of each adjoining substrate; and (h) applying a die-cut stainless steel cover sheet over the outer most cross-linked reaction product material layer thereby defining a fuel cell stack.