EP-4258392-B1 - RAISED FEED CHANNELS TO MAINTAIN PLANAR BIPOLAR PLATE

EP4258392B1EP 4258392 B1EP4258392 B1EP 4258392B1EP-4258392-B1

Inventors

RANIERI, Salvatore
JOOS, NATHANIEL IAN
Rainey Yu, Wang
Link, Thomas Anthony

Dates

Publication Date: 20260506
Application Date: 20230330

Claims (15)

A fuel cell assembly, comprising: a first bipolar plate including a first upper side and a first lower side, the first upper side defines a first top surface and includes a first seal protruding upwardly away from the first top surface and at least one first raised feed channel formed adjacent to the first seal and protruding upwardly away from the first top surface, wherein fluid enters the first raised feed channel and subsequently flows along first channels formed in the first bipolar plate, wherein the at least one first raised feed channel is spaced apart from the first channels and is fluidically connected to the first channels, wherein the at least one first raised feed channel is formed in a first inlet header portion of the first bipolar plate and includes a first opening through which fluid flows from the first raised feed channel and subsequently into the first channels, wherein the at least one first raised feed channel is arranged outwardly of the first seal in a direction away from the first channels; a second bipolar plate including a second upper side and a second lower side, the second lower side defines a second bottom surface and includes a second seal protruding downwardly away from the second bottom surface and at least one second raised feed channel formed adjacent to the second seal and protruding downwardly away from the second bottom surface, wherein fluid enters the second raised feed channel and subsequently flows along second channels formed in the second bipolar plate, wherein the at least one second raised feed channel is spaced apart from the second channels and is fluidically connected to the second channels, wherein the at least one second raised feed channel is formed in a second inlet header portion of the second bipolar plate and includes a second opening through which fluid flows from the second raised feed channel and subsequently into the second channels, wherein the at least one second raised feed channel is arranged outwardly of the second seal in a direction away from the second channels; and a diffusion-electrode assembly arranged between the first bipolar plate and the second bipolar plate and in spaced apart relation to the first and second seals and the first and second raised feed channels, the diffusion-electrode assembly including a membrane electrode layer arranged between a first gas diffusion layer and a second gas diffusion layer each configured to engage with the fluids, respectively, the membrane electrode layer including an electrode body and a membrane frame extending away from the electrode body, between the first and second seals and between the first and second raised feed channels, wherein the first bipolar plate and the second bipolar plate are arranged parallel with each other and are aligned such that the first seal and the second seal align with each other, and such that the first raised feed channel and the second raised feed channel align with each other, and wherein the first raised feed channel and the second raised feed channel contact the membrane frame arranged therebetween so as to prevent mechanical deformations of the first and second bipolar plate.
The fuel cell assembly of claim 1, wherein the first lower side of the first bipolar plate defines a first lower surface and includes a third seal protruding downwardly away from the first lower surface, the third seal being in spaced apart relation to the first seal and the first raised feed channel such that the first raised feed channel is located between the first seal and the third seal in a longitudinal direction of the first bipolar plate, and wherein the contact between the first raised feed channel, the second raised feed channel, and the membrane frame prevents mechanical deformations of the first and second bipolar plates in response to the third seal being acted on by a first external force.
The fuel cell assembly of claim 2, wherein the second upper side of the second bipolar plate defines a second top surface and includes a fourth seal protruding upwardly away from the second top surface, the fourth seal being in spaced apart relation to the second seal and the second raised feed channel such that the second raised feed channel is located between the second seal and the fourth seal in a longitudinal direction of the second bipolar plate, and wherein the contact between the first raised feed channel, the second raised feed channel, and the membrane frame prevents mechanical deformations of the first and second bipolar plates in response to the fourth seal being acted on by a second external force.
The fuel cell assembly of claim 3, wherein the first external force is generated by a third bipolar plate arranged below and compressing the first bipolar plate via a fifth seal of the third bipolar plate, the fifth seal being aligned with and compressing the third seal of the first bipolar plate.
The fuel cell assembly of claim 3, wherein the second external force is generated by a fourth bipolar plate arranged above and compressing the second bipolar plate via a sixth seal of the fourth bipolar plate, the sixth seal being aligned with and compressing the fourth seal of the second bipolar plate.
The fuel cell assembly of claim 1, wherein the first bipolar plate is a rectangular plate that is generally planar, wherein the first inlet header portion is located adjacent a first corner of the plate, a first outlet header portion located adjacent a second corner of the plate diagonally opposing the first corner, a first active portion located longitudinally between the first inlet header portion and the first outlet header portion on which the first channels are arranged, wherein the first channels include a plurality of cathode channels adjacent to the first gas diffusion layer such that fluid flowing through the cathode channels interacts with the first gas diffusion layer, and wherein the first seal and the first raised feed channel are located within the first inlet header portion of the first bipolar plate such that fluid flows from the first raised feed channel to the plurality of cathode channels and exits via the first outlet header portion.
The fuel cell assembly of claim 6, wherein the second bipolar plate is a rectangular plate that is generally planar, wherein the second inlet header portion is located adjacent a first corner of the plate, a second outlet header portion located adjacent a second corner of the plate diagonally opposing the first corner, a second active portion located longitudinally between the second inlet header portion and the second outlet header portion on which the second channels are arranged, wherein the second channels include a plurality of anode channels adjacent to the second gas diffusion layer such that fluid flowing through the anode channels interacts with the second gas diffusion layer, and wherein the second seal and the second raised feed channel are located within the second inlet header portion of the second bipolar plate such that fluid flows from the second raised feed channel to the plurality of anode channels and exits via the second outlet header portion.
The fuel cell assembly of claim 7, wherein the first raised feed channel, the plurality of cathode channels, and at least one first outlet channel located in the first outlet header portion are in fluidic communication so as to form a first fluid path of the first bipolar plate, wherein a first central axis that extends transversely across the plate and that is perpendicular to longitudinal edges of the plate divides the first bipolar plate into a first half portion and a second half portion having equal areas, and wherein the first fluid path is rotationally symmetrical relative to the first central axis.
The fuel cell assembly of claim 8, wherein the second raised feed channel, the plurality of anode channels, and at least one second outlet channel located in the second outlet header portion are in fluidic communication so as to form a second fluid path of the second bipolar plate, wherein a second central axis that extends transversely across the plate and that is perpendicular to longitudinal edges of the plate divides the second bipolar plate into a first half portion and a second half portion having equal areas, and wherein the second fluid path is rotationally symmetrical relative to the second central axis.
The fuel cell assembly of claim 8, wherein the plurality of cathode channels are formed between adjacent elongated cathode channel protrusions that protrude away from the first bipolar plate in a first direction opposite a second direction in which the first raised feed channel protrudes, and wherein the plurality of anode channels are formed between adjacent elongated anode channel protrusions that protrude away from the second bipolar plate in a first direction opposite a second direction in which the second raised feed channel protrudes.
The fuel cell assembly of claim 10, wherein the elongated cathode channel protrusions protrude away from the first bipolar plate a first distance, wherein the elongated anode channel protrusions protrude away from the second bipolar plate a second distance, and wherein the first distance is greater than the second distance.
The fuel cell assembly of claim 11, wherein a third distance that the first and second raised feed channels protrude away from the first and second bipolar plates is an average of the first distance and the second distance.
A method of forming a fuel cell, comprising: providing a plurality of bipolar plates that are generally rectangular and planar, each bipolar plate including (i) a first outer seal protruding downwardly away from the plate, a first inner seal protruding upwardly away from the plate, and a first raised feed channel protruding upwardly away from the plate, the first outer seal, the first inner seal, and the first raised feed channel arranged on an inlet of the bipolar plate, and (ii) a second inner seal protruding downwardly away from the plate, a second outer seal protruding upwardly away from the plate, and a second raised feed channel protruding downwardly away from the plate, the second outer seal, the second inner seal, and the second raised feed channel arranged on an outlet of the bipolar plate, the inlet being located in a first corner of the plate and the outlet being located in a second corner of the plate diagonally opposite of the first corner; providing at least one diffusion-electrode assembly including a membrane electrode and two gas diffusion layers surrounding the membrane electrode, the membrane electrode including an electrode body and a membrane frame extending away from the electrode body; arranging a first bipolar plate of the plurality of bipolar plates in a first position; arranging a first diffusion-electrode assembly of the at least one diffusion-electrode assembly above the first bipolar plate such that one of the two gas diffusion layers is engaged with the first bipolar plate; arranging a second bipolar plate of the plurality of bipolar plates above the first diffusion-electrode assembly such that the other of the two gas diffusion layers is engaged with the second bipolar plate, wherein the second bipolar plate is arranged on the first diffusion-electrode assembly rotated 180 degrees clockwise or counterclockwise relative to the first bipolar plate about a central axis that extends through a central point of the rectangular plate and that is perpendicular to the plate such that the second outer seal, the second inner seal, and the second raised feed channel of the second bipolar plate are aligned with the first outer seal, the first inner seal, and the first raised feed channel of the first bipolar plate, respectively, wherein the membrane frame is located between the first and the second raised feed channels such that the first and the second raised feed channels contact the membrane frame so as to prevent mechanical deformations of the first and second bipolar plate, and wherein the first and second raised feed channels are spaced apart from the first channels and are fluidically connected to the first channels, wherein the first and second raised feed channels each include an opening through which fluid flows from the respective raised feed channel and subsequently into the respective channels, wherein the first and second raised feed channels are arranged outwardly of the respective inner seal in a direction away from the respective channels.
The method of claim 13, further comprising: arranging an additional bipolar plate and an additional diffusion-electrode assembly above or below one of the first and second bipolar plates, wherein the additional bipolar plate is rotated 180 degrees relative to the one of the first and second bipolar plates such that the second outer seal, the second inner seal, and the second raised feed channel of the additional bipolar plate are aligned with the first outer seal, the first inner seal, and the first raised feed channel of the one of the first and second bipolar plates, respectively.
The method of claim 14, wherein the first outer seal and the first inner seal are spaced apart from each other in a longitudinal direction of the plate, wherein the first raised feed channel is located between the first outer seal and the first inner seal, wherein the second outer seal and the second inner seal are spaced apart from each other in a longitudinal direction of the plate, and wherein the second raised feed channel is located between the second outer seal and the second inner seal.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This non-provisional application claims the benefit and priority, under 35 U.S.C. § 119(e) and any other applicable laws or statutes, to U.S. Provisional Patent Application Serial No. 63/328,146 filed April 06, 2022, the entire disclosure of which is hereby expressly incorporated herein by reference. TECHNICAL FIELD The present disclosure generally relates to components and methods for maintaining a unit cell planar alignment during a stack assembly and/or reducing the number of components required for a robust cell-stack assembly. BACKGROUND A single fuel cell is one of many repeating units of a fuel cell stack that may provide power or energy for personal and/or industrial use. A typical proton exchange membrane (PEM) fuel cell is comprised of many fuel cell assemblies compressed and bound into a fuel cell stack. A PEM fuel cell is a multi-component assembly that often comprises a membrane electrode assembly (MEA) at the center, a gas diffusion layer (GDL) on either side of the membrane electrode assembly (MEA), and a bipolar plate (BPP) on either side of each gas diffusion layer (GDL). The membrane electrode assembly (MEA) is the component that enables electrochemical reactions in the fuel cell and/or fuel cell stack. Typically, the fuel cell and/or fuel cell stack is assembled with the aforementioned components to operate in a useful and reliable manner. In most mobility applications, reactants supplied to the fuel cell are pure hydrogen for an anode and an oxidant for a cathode. In the cathode, nitrogen often accompanies oxygen as the supply is from atmospheric air to avoid onboard storage. The anode is typically supplied with pure hydrogen from highly compressed gaseous or liquefied hydrogen stored in onboard tanks. A cooling system is often required to provide a heat sink to manage excess heat produced during the electrochemical reactions and to keep the fuel cell at an appropriate temperature during operation. The fuel cell stacks have common aligned features that allow for a single supply path and return path for each of the anode fluids, cathode fluids, and coolant fluids. These aligned features create a stack-long cavity for the product and reactant fluid to flow, to simultaneously facilitate the supply, and return of the process streams from all the fuel cells in a parallel flow configuration. Since the cells share a common supply and return cavity or manifold, a near equal amount of the reactants and the coolant fluid is diverted to each individual cell and through their respective isolated pathway(s). Such channels or pathways that travel over the length of the bipolar plate (BPP) are referred to as flow field(s). The flow field consists of millimeter scale channel networks that direct the bulk supply of reactants from the manifolds, and distribute and diffuse the reactants over an active area of the fuel cells. The active area of the fuel cell is the main portion of the fuel cell where both the anode and cathode flow fields directly overlap. The open-faced channel of the anode and cathode flow fields are exposed directly overtop the gas diffusion layer (GDL) and the membrane electrode assembly (MEA). Reactant molecules present in the active area of the membrane electrode assembly (MEA) may produce a voltage potential across the cells and a current draw, or a load, may be supported by the reactant flow rate. As the current demand on the fuel cell increases, the molar flow of the reactants is required to increase proportionally. Adjacent bipolar plates (BPP) house the membrane electrode assembly (MEA) and the gas diffusion layer (GDL) such that overall alignment is maintained. Alignment is important to ensure cell-to-cell features such as manifolds and active areas, as well as external interfacing devices, such as a stack enclosure or CVM clips, are compatible with the stack assembly. Lateral deviation of the cells can cause several operational or manufacturing issues such as premature failure of seals, nonconformance of interfacing parts, and/or troublesome integration. The bipolar plates (BPP) must also be designed in a way that retains a near perfect planar or parallelism between the cells. This is also important for robust assembly and operation of the stack for several reasons. Firstly, the soft goods must be evenly compressed to maintain sufficient electrical contact throughout the active area. Any non-uniformities in compression can cause excessive resistivity within the cells which in turn will cause losses in performance and excess heat generation. Secondly, the bipolar plates (BPP) must be symmetrically compressed to avoid any excessive local stress, which can result in local bending and/or fracture of the plates. Bending is more often associated with a poorly designed metallic bipolar plate (BPP) while fracture is a likely failure if a graphite bipolar plate (BPP) is poorly designed. Accordingly, it would be advantageous to provide a fuel cell