High efficiency pem fuel cell

Abstract

A high-efficiency fuel cell includes a first bipolar plate having a cathode flow field on a first surface and an anode flow field on a second surface, a first end, and a second end. The first end of the bipolar plate includes a single air inlet, a single water inlet, and a hydrogen inlet, and the second end of the bipolar plate includes a single cathode fluid outlet and a hydrogen outlet. The air inlet and water inlet are fluidly connected to the cathode flow field via a cathode flow field inlet, and the cathode outlet area is at least 20% larger than the areas of the water inlet and air inlet.

Description

[0001] Cross-reference to related applications This application is a PCT application that claims priority to provisional application number 63 / 733,382, filed on 12 December 2024; and UK patent application number 2319824.4, filed on 21 December 2023, the entire disclosure of which is incorporated herein by reference as if fully set forth. Technical Field

[0002] This disclosure relates to fuel cell stacks, and more particularly to outlet fluid pressure control in membrane fuel cells. Background Technology

[0003] A typical fuel cell system includes a fuel cell stack for generating electricity, a hydrogen supply to the fuel cell stack as fuel, an oxygen (air) supply system for supplying oxygen-containing air as an oxidant in the electrochemical reaction, and a thermal management system for removing reaction heat from the fuel cell stack and managing humidity and dehydration within the stack. The fuel cell system generates heat, water, and electricity.

[0004] In a fuel cell assembly, each unit has an anode, a cathode, and an electrolyte (electrolyte membrane). Hydrogen is supplied to the anode, and oxygen-containing air is supplied to the cathode. Through the membrane electrode assembly (MEA), hydrogen and oxygen generate electricity, heat, and water.

[0005] A fuel cell stack is formed from multiple such fuel cells, each with its own anode and cathode fluid flow paths. Such stacks are typically block-shaped, comprising multiple individual fuel cell plates held together by endplates at either end of the stack. Importantly, the polymer ion transfer membrane remains hydrated for efficient operation. Controlling the stack's temperature is also crucial. Therefore, a coolant can be supplied to the stack for cooling and / or hydration.

[0006] In a hydrogen fuel cell, hydrogen is supplied to the fuel cell from an external source. Such fuel cells typically include a proton exchange membrane (PEM) sandwiched between electrodes, which together constitute a membrane electrode assembly (MEA).

[0007] A critical consideration in the operation of this type of fuel cell is water management within the system. During PEM fuel cell operation, product water from the reaction between hydrogen and oxygen forms at the catalytic sites of the MEA. This water is generated in one or more of the liquid, gas, and transition phases, depending on temperature and pressure, and must be expelled from the MEA via the cathode diffusion structure while oxygen is being delivered to the cathode surface of the MEA. However, it is equally important that the MEA be properly hydrated to ensure that the cell's internal resistance remains within tolerable limits. Failure to control MEA humidification can lead to hot spots and potential cell failure and / or poor cell performance. The anode and cathode fluid flow field plates may each comprise a rigid conductive material with fluid flow pathways in the surface adjacent to the respective diffusion structure for transporting reactant gases (e.g., hydrogen and oxygen) and removing exhaust gases (e.g., unused oxygen and water vapor).

[0008] A fuel cell stack comprises a series of individual fuel cells arranged in a stack-like configuration. Each fuel cell itself may include various layered components such as a polymer electrolyte membrane, a gas diffusion layer, fluid flow plates, and various sealing gaskets for maintaining fluid tightness and distributing fluid fuel and oxidant to the active surfaces of the membrane. Fluid input and output are guided through flow fields and plates at the fuel cell level and through connecting manifolds at the stack level. Common piping is typically used to supply oxidant and fuel to each fuel cell in the fuel cell assembly that forms the stack.

[0009] In a typical high-power fuel cell arrangement, cooling fluid is injected into and dispersed on the anode or cathode side of the fuel cell. Uneven cooling is suboptimal and affects the uniformity of operation and reduces efficiency.

[0010] Other challenges in fuel cell assemblies include ensuring a uniform flow field for the distribution of fluids in the fuel, oxidant, and coolant. Bottlenecks in the input or output of fuel, oxidant, or water can lead to uneven performance of the fuel cell within the stack. In space-constrained applications, the footprint of the fuel cell stack can be critical, and the type and number of external support structures connected to the stack influence this footprint. Reducing waste in the construction of the plates forming the fuel cell assembly can lower costs and carbon footprint.

[0011] High-efficiency PEM fuel cells (PEMFCs) generate heat during operation, and the removal or management of heat from the fuel cell stack is a significant factor as it directly impacts system efficiency. To maintain the temperature within the nominal range while current flows, heat must be reduced or removed. Therefore, there is an urgent need to: (1) reduce uneven heat removal within the fuel cell stack; (2) reduce fluid flow restrictions within the stack; (3) reduce uneven cooling of the fuel cell within the stack; and (4) reduce the footprint of the fuel cell stack. Summary of the Invention

[0012] The following description of the implemented embodiments is taken with reference to the accompanying drawings, which form a part thereof, and the drawings illustrate, by way of illustration, specific implementations of the present disclosure that can be utilized. Other implementations may be utilized, and structural changes may be made without departing from the scope of the present disclosure.

[0013] Exemplary implementations for reducing uneven heat removal in fuel cells forming fuel cell stacks are disclosed.

[0014] Exemplary implementations for reducing fluid flow restrictions within a fuel cell stack are disclosed.

[0015] Exemplary implementations for reducing uneven cooling of fuel cells within a fuel cell stack are disclosed.

[0016] Exemplary embodiments of apparatus, systems, and methods for reducing uneven cooling of fuel cells within a fuel cell stack are disclosed. The aspect includes using a bipolar frame having a first end and a second end, and having two surfaces, the first surface being configured as an anode flow field and a cathode flow field on opposite sides of the bipolar plates. The first end includes one of a single air inlet or a single air outlet, a single water inlet, and one of a single hydrogen outlet or a single hydrogen inlet. The second end includes a single cathode fluid outlet and a single hydrogen inlet or a single hydrogen outlet. The air inlet and water inlet are fluidly connected to one of the cathode flow fields or the anode flow fields, wherein the cathode flow field is fluidly connected to a cathode flow field outlet, and the cathode flow field outlet is fluidly connected to a cathode fluid outlet; and wherein the cathode outlet area is at least 20% larger than the combined area of ​​the cathode water inlet and air inlet, at least 25% larger than the combined area of ​​the cathode water inlet and air inlet, and at least 30% larger than the combined area of ​​the cathode water inlet and air inlet. In some cases, the system includes an anode gas diffusion layer in fluid communication with the anode flow field, a membrane electrode assembly (MEA) in contact with the anode gas diffusion layer on its second side, and a cathode gas diffusion layer in contact with the first side of the MEA. In some cases, the system includes an anode gasket that, when compressed into the fuel cell, forms a seal around the anode face of the bipolar frame; and a cathode gasket that, when compressed into the fuel cell, forms a seal around the cathode face of the bipolar plate. In some cases, the system includes a cathode inlet cap fixed at a first end of the bipolar frame, a cathode outlet cap fixed above a second end of the bipolar frame, and a water guide fixed to at least a portion of at least one of the first end and the cathode inlet cap. In some cases, the hydrogen fluid flow is in the same direction as the air and water fluid flow from end to end of the bipolar plates (one or more). In some cases, the hydrogen fluid flow is in the opposite direction to the air and water fluid flow from end to end of the bipolar plates (one or more).

[0017] Exemplary embodiments of apparatus, systems, and methods for reducing uneven cooling of a fuel cell within a fuel cell stack are disclosed. This aspect includes a first bipolar plate having a cathode flow field on a first surface, an anode flow field on a second surface, a first end, and a second end. It also includes a second bipolar plate having a cathode flow field on the first surface, an anode flow field on the second surface, a first end, and a second end. A median exchange (MEA) is provided between the cathode flow field of the first bipolar plate and the anode flow field of the second bipolar plate. A gas diffusion layer is provided between the MEA and each flow field, and the first end of each bipolar plate includes a single air inlet, a single water inlet, and a hydrogen outlet. The second end of each bipolar plate includes a single cathode fluid outlet and a hydrogen inlet. The configuration is such that the air inlet and water inlet are fluidly connected to the cathode flow field via the cathode flow field inlet, the cathode flow field is fluidly connected to the cathode flow field outlet, the cathode flow field outlet is fluidly connected to the cathode fluid outlet, and the cathode outlet area is one of the following: at least 20% larger than the area of ​​the water inlet and air inlet, at least 25% larger than the area of ​​the water inlet and air inlet, and at least 30% larger than the area of ​​the water inlet and air inlet.

[0018] In some cases, the cathode gasket is configured to form a seal around the cathode surface of the first bipolar plate and the MEA, and the anode gasket is configured to form a seal around the anode surface of the second bipolar frame and the MEA.

[0019] Exemplary embodiments of apparatus, systems, and methods for reducing uneven cooling of fuel cells within a fuel cell stack are disclosed, the fuel cell stack being configured with a plurality of high-efficiency fuel cells formed as a stack. An intake manifold formed within the fuel cell stack is fluidly connected to the cathode flow field of each high-efficiency fuel cell in the stack, and a cathode exhaust manifold formed within the fuel cell stack is fluidly connected to the anode flow field of each high-efficiency fuel cell in the stack. In some cases, the standard liters / minute fluid flow rate through the cathode flow field of the fuel cells constituting the stack is at least 13% greater than the fluid flow rate in a fuel cell stack having multiple cathode flow field inlets and outlets.

[0020] Exemplary embodiments of apparatus, systems, and methods for improving cathode fluid flow within a fuel cell stack are disclosed, comprising placing multiple cells forming the stack. Each fuel cell has a bipolar plate having a cathode flow field on a first side, an anode flow field on a second side, a first end, and a second end. A single air inlet and a single water inlet are formed at the first end of each bipolar plate. A single cathode fluid outlet is formed at the second end of each bipolar plate. An MEA (Mechanical Absorber) is sandwiched between gas diffusion layers on each side. The MEA and the gas diffusion layers are placed between the bipolar plates. An air intake manifold fluidly connected to the cathode flow field of each fuel cell in the stack is formed within the fuel cell stack, and a cathode exhaust manifold fluidly connected to the cathode flow field of each fuel cell in the stack is formed within the fuel cell stack.

[0021] In some cases, gaskets are placed between the bipolar plates to seal them, thereby sealing the cathode and anode flow fields and preventing leakage. In some cases, the area of ​​the cathode exhaust manifold is at least one of the following: at least 20% larger than the area of ​​the intake manifold, at least 25% larger than the area of ​​the intake manifold, or at least 30% larger than the area of ​​the intake manifold. In some cases, the standard liters / minute fluid flow rate through the cathode flow field of the fuel cell stack is at least 13% larger than the fluid flow rate in a fuel cell stack with multiple cathode flow field inlets and outlets. In some cases, the area of ​​the cathode exhaust manifold is at least one of the following: at least 50% larger than the area of ​​the intake manifold, at least 60% larger than the area of ​​the intake manifold, or at least 70% larger than the area of ​​the intake manifold. In some cases, the area of ​​the cathode exhaust manifold is at least one of the following: at least 80% larger than the area of ​​the intake manifold, at least 90% larger than the area of ​​the intake manifold, or at least 100% larger than the area of ​​the intake manifold.

[0022] Exemplary embodiments of apparatus, systems, and methods for improving fluid flow within a fuel cell stack are disclosed. Each fuel cell has a bipolar plate having a cathode flow field on a first surface and an anode flow field on a second surface. An aspect of the high-efficiency fuel cell assembly includes a bipolar frame having an inlet end and an outlet end, and having two surfaces, the first surface configured as the anode flow field and the opposite side of the bipolar plate as the cathode flow field. The inlet end includes an air inlet, a water inlet, and a hydrogen inlet. The outlet end includes a cathode fluid outlet and a hydrogen outlet.

[0023] In some cases, the air inlet and water inlet are in fluid communication with the cathode flow field, the hydrogen inlet and hydrogen outlet are in fluid communication with the anode flow field, and the hydrogen inlet and hydrogen outlet are located at opposite corners of the anode flow field.

[0024] The anode and cathode fluids flow in the same direction (parallel or parallel flow) or in opposite directions on one side of the bipolar plate—the fluid on the anode side usually flows in the opposite direction to the fluid on the cathode side.

[0025] In some cases, the air inlet and water inlet are in fluid communication with the anode flow field, and the hydrogen inlet and hydrogen outlet are in fluid communication with the cathode flow field, and the hydrogen inlet and hydrogen outlet are located at opposite corners of the anode flow field. Attached Figure Description

[0026] This application will be further understood when read in conjunction with the accompanying drawings. For the purpose of illustrating the subject matter, exemplary aspects of the subject matter are shown in the drawings; however, the subject matter of this disclosure is not limited to the specific methods, apparatus, and systems disclosed.

[0027] The components in the accompanying drawings are not necessarily drawn to scale; rather, the focus is on illustrating the principles of the invention. In the drawings, the same reference numerals denote corresponding parts in different views.

[0028] Figure 1 A side-view exploded assembly diagram of a high-efficiency fuel cell assembly is depicted.

[0029] Figure 2 An exploded assembly perspective view depicting the high-efficiency fuel cell assembly from the anode side to the cathode side is shown.

[0030] Figure 3 Depicting Figure 1 A top view of the anode side of a frame with an anode flow field for a high-efficiency fuel cell assembly.

[0031] Figure 4A Depicting Figure 1 A top view of the cathode side of a frame with a cathode flow field in a high-efficiency fuel cell assembly.

[0032] Figure 4B Depicting Figure 4A A top view of the cathode side of the frame of a high-efficiency fuel cell assembly, on which the cathode components are assembled.

[0033] Figure 5 A top view of the cathode side of a high-efficiency fuel cell assembly is depicted.

[0034] Figure 6A and Figure 6B The flow directions on the anode and cathode sides of the bipolar plate are depicted, illustrating the co-current and counter-current flow of fluid above the anode and cathode surfaces of the bipolar plate.

[0035] Figure 7 It is a fuel cell stack formed by multiple high-efficiency fuel cell components.

[0036] All descriptions and references in the accompanying drawings, and all contents thereof, are incorporated herein by reference as if fully set forth herein. Aspects of this disclosure will now be described in detail with reference to the accompanying drawings, wherein, unless otherwise stated, the same reference numerals always refer to the same elements. Detailed Implementation

[0037] This disclosure can be more readily understood by referring to the following detailed description, in conjunction with the accompanying drawings and embodiments, which form part of this disclosure. It should be understood that this disclosure is not limited to the specific apparatus, methods, applications, conditions, or parameters described and / or shown herein, and the terminology used herein is for illustrative purposes only and is not intended to limit the scope of the claimed disclosure.

[0038] This document discloses methods and systems to provide at least one of the following: improvements, cooling, and consistent compression of at least one of a fluid flow plate, a flow assembly, a fuel cell, and a fuel cell stack, which improve power generation efficiency and reduce production costs.

[0039] By rationally designing the dimensions of the cathode inlet and outlet, predictable and uniform fluid flow is achieved to maintain the nominal pressure across the cathode flow field and into the gas diffusion layer (GDL) from inlet to outlet on the cathode side of the fuel cell. The expansion of air (oxidant) flowing across the cathode side of the fuel cell assembly results in a volumetric inlet expansion of at least 5 times or more, in some cases 50 times or more, in some cases 100 times or more, and in some cases 200 times or more. By minimizing bottlenecks, the example fuel cell assembly, the fuel cell formed from such assemblies, and the stack formed from multiple such fuel cells are more efficient fuel cell stacks. Greater efficiency refers to increased power density during operation compared to conventional fuel cells or stacks utilizing the outlet and inlet of conventional fuel cell assemblies.

[0040] Figure 1 This is an overview of fuel cell components and fuel cell parts.

[0041] When two fuel cell components 10 and 10' (each component having bipolar plates that provide a fluid flow path) are stacked together and compressed into part of a fuel cell stack, they cooperate with each other and together serve as fuel cell 100 in that stack.

[0042] Figure 2 This shows aspects of the fuel cell assembly viewed from the cathode side upwards. Figure 3 Figure 6 shows the following aspects: the anode side of the bipolar plate, the cathode side of the bipolar plate of this disclosure, and the cathode side of the bipolar plate of this disclosure.

[0043] A membrane electrode assembly (MEA) containing a proton exchange membrane (also known as a polymer electrolyte membrane) is typically a multilayer interface, through which protons from the anode side of the fuel cell pass through the MEA, and stripped electrons travel around the external circuitry to generate electricity. Oxygen is supplied on the cathode side, and hydrogen protons eventually combine with some of the supplied oxygen to form water.

[0044] Traditionally, the MEA 12 in a fuel cell assembly (or fuel cell) has several gas diffusion layers (or layers) between the MEA and the bipolar frame 13. A cathode gas diffusion layer (or layers) 15 is located on the first side of the cathode face 14 closest to the bipolar frame 13 in the MEA 12A. An anode gas diffusion layer 17 is located on the opposite second side of the anode face 16 closest to the bipolar frame 13 in the MEA 12B. The bipolar frame 13 has a first end 18 opposite a second end 19. A bipolar frame is disclosed herein configured such that the anode face 16 is formed as part of the bipolar frame. A novel bipolar plate 200 is disclosed herein, wherein the cathode face has a separate cathode outlet cap 20 attached to the bipolar frame and a separate cathode inlet cap 22 attached to the bipolar frame. Configuring the bipolar frame 13 to fix separate cathode inlet and outlet caps eliminates the waste material caused by using a single cathode frame, thereby reducing at least one of carbon footprint, cost, and manufacturing cost. A separate water distribution cover 30 may be attached, optionally fixed above at least a portion of the cathode inlet cover. During fuel cell formation within the fuel cell stack, one or more gaskets are added to seal the fuel cell assembly. At least a cathode gasket 40 and an anode gasket 42 may be present.

[0045] Figure 3 The anode side of the bipolar plate is shown. At the first end 18 are an air inlet 300, a water inlet 310, and a hydrogen outlet 315. At the second end 19 are a cathode fluid outlet 320 and a hydrogen inlet 325. The hydrogen inlet is fluidly connected to the anode surface of the bipolar plate via a first anode fluid channel 330. The anode surface is fluidly connected to a second anode fluid channel 335, which is fluidly connected to the hydrogen outlet 315. The water inlet 310 and the air inlet 300 are fluidly connected to the cathode surface of the bipolar plate. Those skilled in the art will recognize that, within the scope of this disclosure, the fluid flow on the anode and cathode sides of the bipolar plate can be co-current (in the same direction from one end to the other) or counter-current (generally opposite directions from one end to the other), see [reference]. Figure 6A and Figure 6B .

[0046] In some cases during operation, hydrogen flows into the flow field from inlet 325 (opposite to the bipolar plate fluid flow at the cathode side) and moves diagonally across the flow field toward outlet 315, roughly along the line of arrow 500. The diagonal alignment of a single hydrogen inlet with a single hydrogen outlet facilitates hydrogen flow through the flow field with fewer low-activity zones and fewer or no dead zones (where insufficient hydrogen is supplied to the MEA). Dead zones and inefficient zones due to lack of hydrogen during operation reduce the power density of the fuel cell. By reducing and eliminating these less-than-ideal conditions within the anode flow field, the fuel cell can operate at higher efficiency, i.e., generating electricity during peak performance at or near the maximum voltage of the fuel cell. In other cases, hydrogen flows in the same direction as or in the same direction as the fluid flow at the bipolar plate cathode side.

[0047] Figure 4A The unassembled cathode side of the bipolar frame 13 is shown. A cathode outlet cap 20 is attached to the bipolar frame at its first end 18, aligned with the bipolar frame's water inlet, air inlet 300, and hydrogen outlet 315. A first cathode fluid channel 340 is formed at one edge of the cathode inlet cap 22. A separate cathode inlet cap 22 is attached to the bipolar frame at its second end 19, aligning the bipolar frame's cathode inlet 300 and hydrogen outlet. A second cathode fluid channel 345 is formed at one edge of the cathode outlet cap 20. Once the cathode caps are attached, the bipolar plate is formed. Those skilled in the art will recognize that conventional bipolar plates utilizing multiple frames fixed together and bipolar plates with a single frame and no cap are both within the scope of this disclosure. Optionally, a separate water guide 30 or dispensing device, such as a separate water dispenser cap, is configured to be fixed above at least a portion of the cathode inlet cap. The air inlet 300 and water inlet 310 are fluidly connected to the cathode surface of the bipolar plate via the first cathode fluid channel 340. The cathode surface is fluidly connected to the second cathode fluid channel 345, and the second cathode fluid channel 345 is fluidly connected to the cathode fluid outlet 320.

[0048] Figure 4B The assembly of the cathode side of the bipolar plate 200B is shown, which includes an optional water distribution cover.

[0049] Figure 5 The assembled bipolar plate is shown with the cathode surface facing upwards and the cathode gas diffusion layer 15 visible. A fluid 510 containing air, water, and water vapor from the air inlet 300 and water inlet 310 fluidly flows along the line of arrow 510 through the first cathode fluid channel 340, through the cathode surface 14 and the cathode gas diffusion layer 15 to the second cathode fluid channel 345, and then to the cathode fluid (or exhaust) outlet 320. The positions of the water inlet and air inlet, and the water outlet and air outlet, can be reversed depending on whether the bipolar plate operates with unidirectional or counter-directional flow.

[0050] Figure 6 shows an assembly diagram of a fuel cell stack 600 formed by multiple fuel cell components 10 (1-N), a cathode gas diffusion layer 14, a first end plate 602, and a second end plate 604. The outlet 605 is also in fluid communication with the cathode fluid outlet.

[0051] Figure 6A and Figure 6B The bipolar plate is shown. With the anode side facing upwards and along the cathode side, fluid flow 510 is shown as a dashed line.

[0052] In a co-flow or parallel flow system, there is an inlet end 525 and an outlet end 535, whereby the inlet end 525 locates all fluid inlets on the anode and cathode sides, and the outlet end 535 locates all fluid outlets. Similar to the above description, the fluid flow of hydrogen 500 is preferably propelled from the diagonal inlet 527 to the diagonal hydrogen fluid outlet 537. As indicated by the fluid direction flow arrow 510, the fluid flow of air and water travels in a generally linear path from the inlet end 525 to the outlet end 535.

[0053] In the opposite operation or system, there is an inlet end 525, through which the fluid inlet of the cathode side (e.g., air and water) travels through the plate to the outlet end 535 as indicated by the fluid direction flow arrow 510. However, as described above, the hydrogen fluid inlet 527 is located in a corner region on the fluid outlet end 535. Similarly, the hydrogen fluid outlet 537 is located at the corner diagonally opposite the hydrogen inlet on the inlet end 525.

[0054] Figure 7 The fuel cell stack shown illustrates that the cathode inlet and outlet cathode fluid manifolds between fuel cells 10 (1-N) are integrated within the fuel cell stack and eliminated from the outside of the fuel cell stack. In some cases of the fuel cell stack shown in Figure 6, the hydrogen inlet and outlet manifolds between fuel cells 10 (1-N) are integrated within the fuel cell stack and eliminated from the outside of the fuel cell stack. An example shows an inlet manifold 300' formed within the fuel cell stack 600, configured to be fluidly connected to the inlet 300 of the bipolar plates 10 (1-N), whereby air (oxidant) is uniformly distributed from the inlet manifold into the cathode flow field of each fuel cell. A compressor or pump directing air to the inlet manifold 300' is not shown. A cathode exhaust manifold 320' is formed within the fuel cell stack, configured to be fluidly connected to the bipolar plate cathode fluid outlet 320, whereby the cathode exhaust fluid (air, water, and water vapor) is collected in the exhaust manifold.

[0055] This document discloses a fuel cell formed from such bipolar plates, wherein a single inlet can be formed in the fuel cell assembly for each of hydrogen, air, and water. Alternatively, there can be only a single outlet for air and water, and a single outlet for hydrogen not used during fuel cell operation. By eliminating the frame portion traditionally used to form multiple outlets in a fuel cell assembly, a fuel cell manifold for collecting and distributing fluids within the fuel cell stack can be formed, thereby eliminating external manifolds and fluid paths, and thus reducing the footprint of the fuel cell stack.

[0056] During fuel cell operation, the heat from the reaction heats the system, which is then cooled by water. Water and air enter from the first side of the bipolar plate via the first cathode fluid channel, flow through the cathode flow field to the second cathode fluid channel, and exit from the cathode outlet at the second end. Water vapor is formed during this flow, and the air is heated, causing the fluid volume to expand. Conventional fuel cells have an inlet on one side of the bipolar plate with the same dimensions as the outlet on the other side. This size mismatch restricts fluid flow, and this restriction is further exacerbated by the uneven pressure along the length of the fuel cell stack in the cathode exhaust collection region.

[0057] In this disclosure, the area of ​​the cathode fluid outlet 320 is proportionally larger than the areas of the combined cathode inlet 300 and water inlet 310. This dimensional difference accommodates an absolute flow rate with a higher volumetric flow rate. When we compare a conventional multi-cathode inlet and water inlet fuel cell, which also has multiple cathode fluid outlets, with the fuel cell disclosed herein, we determine that the fluid flow rate of the conventional arrangement is 10,856 standard liters per minute, while the fluid flow rate of the disclosed fuel cell is 12,406 standard liters per minute, or an increase of approximately 13.5%. In practice, if the volume of the fuel cell power system is not a factor (e.g., a stationary power system), the cathode outlet area will increase by at least one of the following: at least 1.8 times that of the inlet, at least 1.85 times that of the inlet, at least 1.9 times that of the inlet, at least 1.95 times that of the inlet, and at least 2.0 times that of the inlet. In the disclosed configuration, which is also applicable to mobile applications, the cathode outlet area is moderately increased by at least one of 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, and 29% compared to the cathode inlet area. In other cases, depending on space constraints, it may be appropriate to increase the cathode outlet area by at least one of 30%, 40%, 50%, 60%, and 70% compared to the cathode inlet area. Those skilled in the art will recognize that the above-described changes, encompassing increasing the outlet size to accommodate the increased volumetric flow rate of the heated cathode fluid to limit bottlenecks, are all within the scope of this disclosure.

[0058] In conventional fuel cell stack designs with multiple cathode fluid inlets and outlets, a pressure drop occurs in the stack during operation for each inlet and outlet of the same total area. A higher pressure deviation (for the cathode outlet fluid) exists in fuel cells in the stack closest to the external manifold fluid connection, resulting in higher volumetric flow rates for these cells compared to those further from the manifold fluid connection. This creates variations in each fuel cell based on its location within the stack, degrading overall performance. Furthermore, additional energy must traditionally be consumed to increase the force at the compressor used to feed air (oxidant) into the fuel cell stack at the fuel cell cathode inlet to mitigate these deviations.

[0059] In this disclosure, the area of ​​a single cathode fluid outlet 320 is larger than the cathode inlet area and forms a manifold, with each fuel cell outlet fed into the manifold in an unrestricted manner, at least reducing and / or eliminating deviations. In some cases, this disclosure also at least eliminates and / or reduces parasitic losses caused by the increased energy required at the compressor to supply air to the cathode inlet.

[0060] This paper discloses an aspect of a more compact fuel cell assembly formed as a more compact fuel cell, which is stacked in groups to form a more compact fuel cell stack. The more compact fuel cell stack, measured as power density / total system volume, has a higher power density than a conventional fuel cell stack consisting of fuel cells with multiple cathode-side inlets and outlets as well as an external manifold.

[0061] The systems described throughout this disclosure can be used in a variety of applications to provide electricity generated by fuel cells. In some aspects, the systems disclosed throughout this application can be used in machine handling equipment (MHE), such as forklifts. In some aspects, the systems can be used in unmanned aerial vehicles (UAVs), such as fixed or multi-rotor UAVs. In some aspects, the systems disclosed herein can be used in automotive, rail, or aerospace applications, such as cars, trucks, trains, aircraft, or stationary power systems. It should be understood that these systems can be used in a variety of other applications, and certain functionalities and physical parameters, such as component size and quantity, can vary depending on the specific application and can be determined by the requirements of a particular purpose. Additional advantages of the foregoing include the ability to install the system and related components (such as fuel tank cylinders) in a small space and the ability to arrange the system and related components.

[0062] The components disclosed in this article can utilize known materials used in industry.

[0063] In this specification, terms should be used in their normal meaning as understood by those skilled in the art. However, to avoid misunderstanding, the meanings of certain terms will be specifically defined or clarified.

[0064] While this disclosure has been described with reference to various embodiments in conjunction with the accompanying drawings, those skilled in the art will understand that modifications may be made to the above embodiments without departing from its broad inventive concept. Therefore, it should be understood that this disclosure is not limited to the specific embodiments disclosed, and that it is intended to cover modifications within the spirit and scope of this disclosure as defined in the claims.

[0065] The features of this disclosure described above in the context of individual embodiments may be provided in combination in a single embodiment. Conversely, the various features of this disclosure described in the context of a single embodiment may also be provided individually or in any sub-combination. Finally, while an embodiment may be described as part of a series of steps or a more general structure, each of the steps may also be considered an independent embodiment that may be combined with other steps.

[0066] Unless otherwise stated herein, references to ranges of values ​​herein are intended only as a shorthand way of referring to each individual value within that range, and each individual value is incorporated into the specification as if it were stated separately herein. Unless otherwise stated herein or clearly contradicted by the context, all methods described herein may be performed in any suitable order.

Claims

1. A high-efficiency fuel cell assembly, comprising: A bipolar frame (13) having a first end (18) and a second end (19) and having two surfaces, the first surface being configured as an anode flow field (16) and a cathode flow field (14) on the opposite side of the bipolar plate. The first end includes: A single air inlet (300) or cathode fluid outlet (320), A single inlet (310) or outlet (325), and A single hydrogen outlet (315) or hydrogen inlet (325); The second end includes: A single cathode fluid outlet (320) or inlet (300), and A single hydrogen inlet (325) or hydrogen outlet (315); The air inlet and water inlet are fluidly connected to one of the cathode flow field or the anode flow field; The cathode flow field is fluidly connected to the cathode flow field outlet (345), and the cathode flow field outlet (345) is fluidly connected to the cathode fluid outlet; and... The cathode outlet area is one of the following: at least 20% larger than the combined area of ​​the cathode inlet and air inlet, at least 25% larger than the combined area of ​​the cathode inlet and air inlet, and at least 30% larger than the combined area of ​​the cathode inlet and air inlet.

2. The high-efficiency fuel cell assembly according to claim 1, further comprising: An anode gas diffusion layer, which is in fluid communication with the anode flow field; A membrane electrode assembly (MEA) (12) is in contact with the anode gas diffusion layer on its second side (12B); and, The cathode gas diffusion layer is in contact with the first side (12A) of the MEA.

3. The high-efficiency fuel cell assembly according to claim 2, further comprising: An anode gasket (40) forms a seal around the anode surface of the bipolar frame when compressed into the fuel cell; and, A cathode gasket (42) forms a seal around the cathode surface of the bipolar plate when compressed into the fuel cell.

4. The high-efficiency fuel cell assembly according to claim 3, further comprising: A cathode inlet cover (22) is fixed at the first end of the bipolar frame; A cathode outlet cover (20) is fixed above the second end of the bipolar frame; as well as, A water guide (30) is fixed to at least a portion of at least one of the first end and the cathode inlet cover.

5. The high-efficiency fuel cell assembly according to claim 1, wherein the fluid flow on the cathode side and anode side of the bipolar plate flows in the same direction.

6. The high-efficiency fuel cell assembly of claim 1, wherein the fluid flow on the cathode side and the anode side of the bipolar plate flows in opposite directions.

7. A high-efficiency fuel cell, comprising: The first bipolar plate (200A) includes: The flow field at the cathode (14) on the first surface; The anode flow field on its second surface (16); First end (18); and Second end (19); The second bipolar plate (200A) includes: The flow field at the cathode (14) on the first surface; The anode flow field on its second surface (16); First end (18); and Second end (19); MEA between the cathode flow field of the first bipolar plate and the anode flow field of the second bipolar plate; Gas diffusion layer between the MEA and each flow field; The first end of each bipolar plate includes: Single air inlet (300), A single inlet (310), and Hydrogen inlet (325); The second end of each bipolar plate includes: A single cathode fluid outlet (320), and Hydrogen outlet (315); The air inlet and water inlet are fluidly connected to the cathode flow field via the cathode flow field inlet (340); The cathode flow field is fluidly connected to the cathode flow field outlet (345), and the cathode flow field outlet (345) is fluidly connected to the cathode fluid outlet; and... The cathode outlet area is one of the following: at least 20% larger than the area of ​​the water inlet and the air inlet, at least 25% larger than the area of ​​the water inlet and the air inlet, and at least 30% larger than the area of ​​the water inlet and the air inlet.

8. The high-efficiency fuel cell according to claim 7, further comprising: A cathode gasket, configured to form a seal around the cathode surface of the first bipolar plate and the MEA; and, An anode gasket is configured to form a seal around the anode surface of the second bipolar frame and the MEA.

9. A fuel cell stack comprising: Multiple high-efficiency fuel cells are formed into a stack; An intake manifold formed within the fuel cell stack is fluidly connected to the cathode flow field of each high-efficiency fuel cell in the stack. as well as, A cathode exhaust manifold is formed within the fuel cell stack and is fluidly connected to the cathode flow field of each high-efficiency fuel cell in the stack.

10. The fuel cell stack of claim 9, wherein the standard liters per minute fluid flow rate of the cathode flow field constituting the stack is at least 13% greater than the fluid flow rate in a fuel cell stack having a plurality of cathode flow field inlets and outlets.

11. A method for improving cathode fluid flow within a fuel cell stack, the method comprising: Multiple batteries are arranged to form a fuel cell stack, each fuel cell including: A bipolar plate having a cathode flow field on a first surface, an anode flow field on a second surface, a first end, and a second end; A single air inlet and a single water inlet are formed on the first end of each bipolar plate; A single cathode fluid outlet is formed at the second end of each bipolar plate; The MEA is sandwiched between the gas diffusion layers on each side; The MEA and the gas diffusion layer are placed between the bipolar plates; An intake manifold is formed within the fuel cell stack, fluidly connected to the cathode flow field of each fuel cell in the stack; and, A cathode exhaust manifold is formed within the fuel cell stack and is fluidly connected to the cathode flow field of each fuel cell in the stack.

12. The method of claim 11, wherein a gasket is placed between the bipolar plates to seal the bipolar plates, thereby sealing the cathode flow field and the anode flow field and preventing leakage therefrom.

13. The method of claim 12, wherein the area of ​​the cathode exhaust manifold is at least one of the following: at least 20% larger than the area of ​​the intake manifold, at least 25% larger than the area of ​​the intake manifold, or at least 30% larger than the area of ​​the intake manifold.

14. The fuel cell stack of claim 12, wherein the standard liters / minute fluid flow rate through the cathode flow field of the fuel cell stack is at least 13% greater than the fluid flow rate in a fuel cell stack having a plurality of cathode flow field inlets and outlets.

15. The method of claim 12, wherein the area of ​​the cathode exhaust manifold is at least one of the following: at least 50% larger than the area of ​​the intake manifold, at least 60% larger than the area of ​​the intake manifold, or at least 70% larger than the area of ​​the intake manifold.

16. The method of claim 12, wherein the area of ​​the cathode exhaust manifold is at least one of the following: at least 80% larger than the area of ​​the intake manifold, at least 90% larger than the area of ​​the intake manifold, or at least 100% larger than the area of ​​the intake manifold.

17. A high-efficiency fuel cell assembly, comprising: The bipolar frame (13) has an inlet end (525) and an outlet end (535) and has two surfaces, the first surface being configured as an anode flow field and the opposite side of the bipolar plate as a cathode flow field. The inlet end includes: Single air intake; Single inlet; Hydrogen inlet (527); and, The outlet end includes: Cathode fluid outlet; Hydrogen outlet (537); The air inlet and the water inlet are in fluid communication with the cathode flow field; The hydrogen inlet and the hydrogen outlet are in fluid communication with the anode flow field; and... The hydrogen inlet and the hydrogen outlet are located at opposite corners of the anode flow field.

18. The high-efficiency fuel cell assembly of claim 17, wherein the cathode outlet area is one of the following: at least 20% larger than the combination of the cathode inlet and air inlet areas, at least 25% larger than the combination of the cathode inlet and air inlet areas, and at least 30% larger than the combination of the cathode inlet and air inlet areas.

19. The high-efficiency fuel cell assembly of claim 17, wherein the cathode side and anode side of the bipolar plate are interchanged, wherein hydrogen flows through the cathode side and air and water flow through the anode side.

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