Joining of bipolar plates in proton exchange membrane fuel cell stacks

A fuel cell stack comprising:

• a plurality of membrane electrode assemblies arranged in a stacked configuration;
• a bipolar plate assembly disposed between respective pairs of said membrane electrode assemblies, each said bipolar plate assembly including a pair of aligned plates each having a plurality of reactant gas channels on a first surface facing said membrane electrode assemblies, and a plurality of alternating coolant grooves and lands on a second surface facing away from said membrane electrode assemblies;
• each said second surface having an electrically conductive layer deposited over at least said lands;
• each said bipolar plate assembly joined to form both a plurality of electrical bond lines between respective facing pairs of said lands and a plurality of coolant channels between respective facing pairs of said coolant grooves;
• and
• a fluid seal between respective said second surfaces of said aligned plates and circumscribing said coolant channels and said lands of said respective plates to isolate said reactant gas channels from said electrically conductive layer.

A method of isolating reactant gas passages from coolant contacting surfaces in a fuel cell stack comprising the steps of:

• forming alternating coolant grooves and lands on facing interior surfaces of a plurality of plate pairs;
• providing a plurality of reactant gas passages on exterior surfaces of said plurality of plate pairs;
• conductively plating at least said lands of said facing surfaces;
• aligning both said facing surfaces to form pairs of facing lands;
• sealing a perimeter of said facing surfaces of each plate pair to isolate said coolant grooves and lands from said reactant gas passages;
• and
• joining said plurality of plate pairs to electrically couple said facing lands between each said plate pair.

A bipolar plate assembly comprising:

• a plate pair having plate facing surfaces, each said facing surface including an inner portion and a peripheral outer portion;
• each said inner portion having an alternating plurality of both coolant grooves and lands formed thereon;
• each said peripheral outer portion having at least one reactant port for supplying a reactant gas;
• an electrically conductive layer deposited over at least said lands of each said plate;
• said facing surfaces joined to form both a plurality of electrical bond lines between respective facing pairs of said lands and a plurality of coolant channels between respective facing pairs of said coolant grooves;
• and
• a fluid seal disposed between said inner portion and said peripheral outer portion of said facing surfaces, said fluid seal circumscribing each said inner portion to inhibit crossover of said reactant gas into said inner portion.

A fuel cell stack comprising:

• a plurality of membrane electrode assemblies arranged in a stacked configuration;
• a bipolar plate assembly disposed between respective pairs of said membrane electrode assemblies, each said bipolar plate assembly including a pair of aligned plates each having a plurality of reactant gas channels on a first surface facing said membrane electrode assemblies and a plurality of reactant gas ports supplying reactant gas to said reactant gas channels, and having a plurality of alternating coolant grooves and lands on a second surface facing away from said membrane electrode assemblies;
• each said second surface having an electrically conductive layer deposited over at least said lands;
• each said bipolar plate assembly joined to form both a plurality of electrical bond lines between respective facing pairs of said lands and a plurality of coolant channels between respective facing pairs of said coolant grooves;
• and
• a fluid seal between said ports and said coolant channels and said lands of each said bipolar plate assembly to isolate said reactant gas from said electrically conductive layer.

A method of isolating reactant gas passages from coolant contacting surfaces in a fuel cell stack comprising the steps of:

• forming alternating coolant grooves and lands on facing interior surfaces of a plurality of plate pairs;
• providing a plurality of reactant gas passages on exterior surfaces of said plurality of plate pairs and providing at least one reactant port for supplying a reactant gas;
• conductively plating at least said lands of said facing surfaces;
• aligning both said facing surfaces to form pairs of facing lands;
• sealing a perimeter of said facing surfaces adjacent said port of each plate pair to isolate said coolant grooves and lands from said reactant gas;
• and
• joining said plurality of plate pairs to electrically couple said facing lands between each said plate pair.