Abstract: A method, fuel cell system and vehicle for maintaining compression via re-compression is provided. By recovering fuel cell stacks of the fuel cell system after a pre-determined time of operation and performing re-compression on each of the recovered fuel cell stacks, power generation capacity, active area pressure and seal force is recovered to address increased contact resistance and loss of fuel cell system power generation capacity as well as decreased seal force and increased risk of reactant gas and coolant leak.

Abstract: Presented are shock-force mitigation systems for fuel cell stacks, methods for making/using such systems, and electric-drive vehicles equipped with such systems. A fuel cell system includes multiple electrochemical fuel cells that are stacked face-to-face along a stack axis to define a fuel cell stack. A push plate abuts each longitudinal end of the fuel cell stack; these push plates translate rectilinearly along the stack axis inside a fuel cell stack housing. An end plate is located in facing spaced relation to each push plate to define a plate pair at each end of the stack. An active or passive force-modifying device is interposed between the two plates in each plate pair; these devices modify stack forces experienced by the fuel cell stack. For an active shock-force mitigation system, each force-modifying device may include a bladder system, spring, and/or linear actuator; an electronic system controller controls activation of the bladders/actuators.

Abstract: A fuel cell system includes a plurality of stacked bipolar plate assemblies. Each of the plurality of stacked bipolar plate assemblies includes a first subgasket including a first peripheral edge. The first subgasket supports a first membrane electrode assembly (MEA). A second subgasket including a second peripheral edge supports a second MEA. A bipolar plate is disposed between the first subgasket and the second subgasket. The bipolar plate has a first side defining a first plurality of passages receptive of a cathode fluid, a second side defining a second plurality of passages receptive of an anode fluid, and a plurality of coolant passages defined between the first subgasket and the second subgasket. A seal bead extends around the bipolar plate. The seal bead seals against the first subgasket and the second subgasket. A compliant energy attenuating bumper extends about the bipolar plate spaced from the seal bead.

Abstract: A fuel cell system includes a dry end unit, a wet end unit and a plurality of fuel cells. The dry end unit has a dry base plate and a dry intermediate plate. The dry intermediate plate is initially moveable relative to the dry base plate during a fabrication of the fuel cell system. The wet end unit has a wet base plate and a wet intermediate plate. The wet intermediate plate adjoins the wet base plate. The plurality of fuel cells is disposed between the dry intermediate plate and the wet intermediate plate. Each of the plurality of fuel cells includes a perimeter area that surrounds an active area. The dry intermediate plate is fixed in position relative to the dry base plate during the fabrication to maintain the active areas of the plurality of fuel cells at a target active area pressure.

Abstract: A fuel cell stack assembly includes first and second bipolar plates, an active area membrane, and an optional subgasket. The first bipolar plate defines a first plurality of tunnels and the second bipolar plate defines a second plurality of tunnels. The second plurality of tunnels may be engaged with and nested between the first plurality of tunnels. The active area membrane may be disposed within an internal periphery of a subgasket between the first and second bipolar plates wherein the subgasket may, optionally, be positioned between the first and second plurality of tunnels.

Abstract: A fuel cell stack alignment system includes an alignment guide bar for positioning a plurality of stack components. Each of the stack components has an alignment slot and a spacing slot. A first alignment portion and a second alignment portion of the alignment guide bar has a shape that is complimentary to the shape of the alignment slot of each of the stack components. Abutting engagement between one of the first or second alignment portions and the alignment slot aligns each respective stack component in a respective assembly position. The other of the first and second alignment portions of each respective stack component is disposed within the spacing slot. The spacing slot has a shape that is larger than the first and second alignment portions, to provide a gap between the stack components and the alignment guide bar.

Abstract: Methods for designing one or a pair of half plates of a fuel cell include providing a first half plate defining a first half plate metal bead, wherein the first half plate metal bead protrudes from the first half plate forming a convex side, providing a second half plate defining a second plate metal bead, wherein the second half plate metal bead protrudes from the second half plate forming a convex side, determining a pressure profile between the convex sides of the first half plate metal bead and the second half plate metal bead in a compressed state, and adjusting a height of the first half plate metal bead and/or the second half plate metal bead in one or more locations to increase the uniformity of the pressure profile. Increasing the uniformity of the pressure profile can include reducing a range of the plurality of pressure measurements.

Abstract: An end plate unit for use in a fuel cell stack in an electric vehicle is provided wherein the end plate includes an outer surface, an inner surface disposed opposite the outer surface and a current collector. The inner surface defines at least a first region and a second region which is spaced apart from and substantially parallel to the first region. The current collector may be affixed to the inner surface.

Abstract: A method of manufacturing a fuel cell stack includes compressing a stack of bipolar plates with a variable applied load a feature non-deformed displacement distance, which is measured from an initial height of the stack of bipolar plates. A first applied load at a first displacement distance and a second applied load at a second displacement distance are sensed. The first displacement distance and the second displacement distance are each less than the feature non-deformed displacement distance. A best fit curve, passing through the first applied load at the first displacement distance and the second applied load at the second displacement distance, is then determined. A final displacement distance, measured from the initial height, is calculated from the best fit curve for a target applied load. The stack of bipolar plates is then compressed to the final displacement distance measured from the initial height.

Abstract: A fuel cell stack alignment system includes an alignment guide bar for positioning a plurality of stack components. Each of the stack components has an alignment slot and a spacing slot. A first alignment portion and a second alignment portion of the alignment guide bar has a shape that is complimentary to the shape of the alignment slot of each of the stack components. Abutting engagement between one of the first or second alignment portions and the alignment slot aligns each respective stack component in a respective assembly position. The other of the first and second alignment portions of each respective stack component is disposed within the spacing slot. The spacing slot has a shape that is larger than the first and second alignment portions, to provide a gap between the stack components and the alignment guide bar.

Abstract: Methods for designing one or a pair of half plates of a fuel cell include providing a first half plate defining a first half plate metal bead, wherein the first half plate metal bead protrudes from the first half plate forming a convex side, providing a second half plate defining a second plate metal bead, wherein the second half plate metal bead protrudes from the second half plate forming a convex side, determining a pressure profile between the convex sides of the first half plate metal bead and the second half plate metal bead in a compressed state, and adjusting a height of the first half plate metal bead and/or the second half plate metal bead in one or more locations to increase the uniformity of the pressure profile. Increasing the uniformity of the pressure profile can include reducing a range of the plurality of pressure measurements.

Abstract: A fuel cell stack assembly includes first and second bipolar plates, an active area membrane, and an optional subgasket. The first bipolar plate defines a first plurality of tunnels and the second bipolar plate defines a second plurality of tunnels. The second plurality of tunnels may be engaged with and nested between the first plurality of tunnels. The active area membrane may be disposed within an internal periphery of a subgasket between the first and second bipolar plates wherein the subgasket may, optionally, be positioned between the first and second plurality of tunnels.

Abstract: A fuel cell stack assembly for a vehicle is provided which includes a first end plate, a second end plate; and a first plurality of fuel cells disposed between the first and second end plates. The first plurality of fuel cells may define a repeating pattern of a thick fuel cell adjacent to a thin fuel cell. Each fuel cell in the first plurality of fuel cells having an active area thickness. The fuel cell stack assembly of the present disclosure may further include a second plurality of nominal fuel cells.

Abstract: A method for assembling a fuel cell stack for a vehicle is provided wherein the method includes the steps of: (1) providing a batch of fuel cells having varying active area thicknesses among each fuel cell; (2) measuring an active area thickness for each fuel cell in the batch of fuel cells and sorting each fuel cell in the batch of fuel cells into one of a first group, a second group, and a third group based on the active area thickness for each fuel cell; (3) assembling a target number of fuel cells to a target height from at least one of the first, second and third groups onto a first end plate; and (4) affixing a second end plate to the target number of fuel cells and the first end plate thereby creating a fuel cell stack.

Abstract: A process for manufacturing a stepped UEA includes the steps of providing a major diffusion layer, a PEM layer and a minor diffusion layer onto a lower supporting mold; enclosing the major diffusion layer, a PEM layer and a minor diffusion layer in the lower supporting mold and the upper mold; injecting a polymeric material into the mold; permeating the polymeric material into a peripheral edge area of each of the major and minor diffusion layers and molding the polymeric material directly onto the peripheral edge area of the PEM; and removing the overmolded UEA from the upper mold and lower supporting mold.

Abstract: A stepped UEA for a fuel cell includes a major diffusion layer, a minor diffusion layer, an overmolded subgasket, and a proton exchange membrane layer disposed between the major diffusion layer and the minor diffusion layer. The overmolded subgasket may be directly molded to the peripheral edge region for each of the major diffusion layer, the minor diffusion layer, and the proton exchange membrane layer.

Abstract: A method for assembling a fuel cell stack for a vehicle is provided wherein the method includes the steps of: (1) providing a batch of fuel cells having varying active area thicknesses among each fuel cell; (2) measuring an active area thickness for each fuel cell in the batch of fuel cells and sorting each fuel cell in the batch of fuel cells into one of a first group, a second group, and a third group based on the active area thickness for each fuel cell; (3) assembling a target number of fuel cells to a target height from at least one of the first, second and third groups onto a first end plate; and (4) affixing a second end plate to the target number of fuel cells and the first end plate thereby creating a fuel cell stack.

Abstract: A fuel cell stack assembly for a vehicle is provided which includes a first end plate, a second end plate; and a first plurality of fuel cells disposed between the first and second end plates. The first plurality of fuel cells may define a repeating pattern of a thick fuel cell adjacent to a thin fuel cell. Each fuel cell in the first plurality of fuel cells having an active area thickness. The fuel cell stack assembly of the present disclosure may further include a second plurality of nominal fuel cells.

Abstract: A method of manufacturing a fuel cell stack includes compressing a stack of bipolar plates with a variable applied load a feature non-deformed displacement distance, which is measured from an initial height of the stack of bipolar plates. A first applied load at a first displacement distance and a second applied load at a second displacement distance are sensed. The first displacement distance and the second displacement distance are each less than the feature non-deformed displacement distance. A best fit curve, passing through the first applied load at the first displacement distance and the second applied load at the second displacement distance, is then determined. A final displacement distance, measured from the initial height, is calculated from the best fit curve for a target applied load. The stack of bipolar plates is then compressed to the final displacement distance measured from the initial height.

Abstract: An end plate unit for use in a fuel cell stack in an electric vehicle is provided wherein the end plate includes an outer surface, an inner surface disposed opposite the outer surface and a current collector. The inner surface defines at least a first region and a second region which is spaced apart from and substantially parallel to the first region. The current collector may be affixed to the inner surface.