A fuel cell system with reduced leakage and a method of assembling a fuel cell system. Bipolar plates within the system include reactant channels and coolant channels that are fluidly coupled to inlet and outlet flowpaths, all of which are formed within a coolant-engaging or reactant-engaging surface of the plate. One or more seals are also formed on the fluid-engaging surface to help reduce leakage by maintaining fluid isolation of the reactants and coolant as they flow through their respective channels and flowpaths that are defined between adjacently-placed plates. The seal—with its combination of in-plane and out-of-plane dimensions—forms a substantially hollow volume, into which a plug is placed to reduce the tendency of the seal to form a shunted flow of the coolant or reactant around the intended active area of the plate. A fluid port intersection is integrally formed with the seal and is formed to be fluidly cooperative with the volume, and is capable of accepting the introduction of a fluent precursor of the plug material such that upon curing, the precursor material forms a substantially rigid insert that continuously fills both the volume and intersection, thereby increasing the resistance of the plug to movement and the seal to shunted flow. In one form, the geometry of the fluent material injection site is such that it promotes plug anchoring within its intended location, while also providing a manufacturing aid to visually inspect for plug installation, as well as to serve as a bipolar plate stacking alignment locator and verification.

A fluid flow field of a separator of a fuel cell stack allows a fluid to flow in a separator surface direction. A rubber seal member provides a seal between the fluid passage and the fluid flow field. The tunnel portion intersects the rubber seal member at an intersection. The tunnel portion allows the fluid flow field and the fluid passage to connect to each other. In the rubber seal member, a first portion protrudes from a flat portion in a stacking direction, and a second portion protrudes from a protruding end surface of a tunnel portion in the stacking direction.

A fluid flow field of a separator of a fuel cell stack allows a fluid to flow in a separator surface direction. A rubber seal member provides a seal between the fluid passage and the fluid flow field. The tunnel portion intersects the rubber seal member at an intersection. The tunnel portion allows the fluid flow field and the fluid passage to connect to each other. In the rubber seal member, a first portion protrudes from a flat portion in a stacking direction, and a second portion protrudes from a protruding end surface of a tunnel portion in the stacking direction.

A bipolar plate assembly with integrated seal for a fuel cell with a subassembly having a formed metal cathode plate bonded to a formed metal anode plate. On at least one of the plates, two raised continuous ridges are formed on the outward surface of and around the perimeter of the plate, thereby creating a channel to contain the seal. In this design, a substantial portion of the channel area on the inward surface of the plate is in direct contact with and supported by the other plate. The channel and hence the seal are thus well supported during molding and under compression in the assembled fuel cell. Further, ducts traversing the seal region can advantageously be formed without affecting the functioning of the seal.

A bipolar plate assembly with integrated seal for a fuel cell with a subassembly having a formed metal cathode plate bonded to a formed metal anode plate. On at least one of the plates, two raised continuous ridges are formed on the outward surface of and around the perimeter of the plate, thereby creating a channel to contain the seal. In this design, a substantial portion of the channel area on the inward surface of the plate is in direct contact with and supported by the other plate. The channel and hence the seal are thus well supported during molding and under compression in the assembled fuel cell. Further, ducts traversing the seal region can advantageously be formed without affecting the functioning of the seal.

A fuel cell stack in which cell units are stacked one on top of another, each of the cell units including: a power generation cell; and a separator defining and forming a flow passage portion, being a flow path of the gas, between the separator and the power generation cell, includes a frame body having an insulating property and arranged between at least one set of the cell units adjacent to each other. The frame body includes: as viewed in a stacking direction, outer peripheral beam portions provided to surround an outer peripheral side of a region in which the power generation cell is arranged; a connection beam portion connecting the outer peripheral beam portions to each other; and sealing beam portions formed along sealing portions at least partially sealing a manifold portion through which the gas is allowed to flow to the separator.

A membrane electrode assembly for a fuel cell comprises a proton exchange membrane having an anode side and a cathode side. An anode catalyst layer is on the anode side of the proton exchange membrane and a cathode catalyst layer is on the cathode side of the proton exchange membrane. Each of the anode catalyst layer and the cathode catalyst layer comprises a metal alloy. A gas diffusion layer is on each of the anode catalyst layer and the cathode catalyst layer opposite the proton exchange membrane. A sacrificial intercalating agent is between the proton exchange membrane and one of the anode catalyst layer and the cathode catalyst layer, the sacrificial intercalating agent having sulfonate sites that attract metal cations resulting from dissolution of the metal alloy prior to the metal cations reaching the proton exchange membrane.

A membrane electrode assembly for a fuel cell comprises a proton exchange membrane having an anode side and a cathode side. An anode catalyst layer is on the anode side of the proton exchange membrane and a cathode catalyst layer is on the cathode side of the proton exchange membrane. Each of the anode catalyst layer and the cathode catalyst layer comprises a metal alloy. A gas diffusion layer is on each of the anode catalyst layer and the cathode catalyst layer opposite the proton exchange membrane. A sacrificial intercalating agent is between the proton exchange membrane and one of the anode catalyst layer and the cathode catalyst layer, the sacrificial intercalating agent having sulfonate sites that attract metal cations resulting from dissolution of the metal alloy prior to the metal cations reaching the proton exchange membrane.

A fuel cell stack (11) includes a plurality of contiguous fuel cells (13), each including a unitized electrode assembly (15) sandwiched between porous, anode (22) and cathode water transport plates (18). In areas where silicone rubber (29) or other elastomer covers edges of the fuel cells in order to form seals with an external manifold (27), adjacent edges of the water transport plates are supplanted by, or augmented with, an elastomer-impervious material (34). This prevents infusion of elastomer to the WTPs which can cause sufficient hydrophobicity as to reduce or eliminate water bubble pressure required to isolate the reactant gases from the coolant water, thereby preventing gaseous inhibition of the coolant pump. A preformed insert (34) may be cast into the water transport plates as molded, or a fusible or curable non-elastomer, elastomer-impervious in fluent form may be deposited into the pores of already formed water transport plates, and then fused or cured.

A fuel cell stack (11) includes a plurality of contiguous fuel cells (13), each including a unitized electrode assembly (15) sandwiched between porous, anode (22) and cathode water transport plates (18). In areas where silicone rubber (29) or other elastomer covers edges of the fuel cells in order to form seals with an external manifold (27), adjacent edges of the water transport plates are supplanted by, or augmented with, an elastomer-impervious material (34). This prevents infusion of elastomer to the WTPs which can cause sufficient hydrophobicity as to reduce or eliminate water bubble pressure required to isolate the reactant gases from the coolant water, thereby preventing gaseous inhibition of the coolant pump. A preformed insert (34) may be cast into the water transport plates as molded, or a fusible or curable non-elastomer, elastomer-impervious in fluent form may be deposited into the pores of already formed water transport plates, and then fused or cured.