Fuel cell basic unit and fuel cell stack

Abstract

The invention belongs to the technical field of fuel cells, and particularly relates to a fuel cell basic unit and a fuel cell stack, the fuel cell basic unit comprises a variable cross-section bipolar plate, a proton exchange membrane and an anode runner, the proton exchange membrane is arranged between the variable cross-section bipolar plate and the anode runner, and the width of the flow channel in the variable cross-section bipolar plate is gradually increased along the length direction of the variable cross-section bipolar plate. According to the fuel cell basic unit disclosed by the invention, the variable cross-section bipolar plate design is adopted, and the width of the flow channel is gradually increased along the length direction, so that the fuel gas can form gradual flow velocity change in the flowing process, the gas can be more uniformly distributed in the whole reaction area, the reaction efficiency is improved, and the reaction time is shortened. The variable-width cross section design enables a plurality of basic units to be overlapped to form the fuel cell stack with a fan-shaped structure, so that the limitation of a traditional cubic structure is broken through, and the stack can be better adapted to various irregular mounting spaces.

Description

Technical Field

[0001] The present invention belongs to the technical field of fuel cells, and in particular relates to a fuel cell basic unit and a fuel cell stack. Background Art

[0002] As fossil fuel reserves gradually decrease and global carbon emissions become increasingly severe, new energy technologies have ushered in unprecedented development opportunities. Since the 21st century, various types of battery technologies have been continuously innovated, among which lithium batteries and fuel cells have received widespread attention as representative technologies. Lithium batteries have achieved certain success in consumer electronics, portable devices and some electric vehicles with their high energy conversion efficiency and mature commercial applications. Their energy density is generally between 200 and 300Wh / kg. However, with the increasing demand for long battery life and high energy density, fuel cells, due to their energy density usually greater than 1000Wh / kg, have gradually shown unique advantages in transportation, fixed power generation and portable power sources.

[0003] A fuel cell is a device that converts chemical energy stored in fuel and oxidant directly into electrical energy. It has the advantages of high energy conversion efficiency, environmental friendliness, low noise, and high reliability. With the transformation of the global energy structure and the enhancement of environmental protection awareness, fuel cell technology has shown broad application prospects in transportation, fixed power generation, portable power sources and other fields.

[0004] Figure 1 This is the working principle of a fuel cell (taking a membrane electrode fuel cell as an example), hydrogen and oxygen are introduced into the anode 200 and cathode 300 respectively, and then electrons move to the cathode 300 through an external circuit, and hydrogen loses electrons at the anode 200 and becomes hydrogen ions, and then migrates to the cathode 300 through the membrane electrode assembly 100 (proton exchange membrane, catalyst layer, gas diffusion layer), and combines with oxygen to generate water, thereby generating electrical energy 400. The whole process is an electrochemical reaction, and electrical energy is directly generated without a heat engine, so it is highly efficient and the product is clean and pollution-free.

[0005] The fuel cell stack is the core component of the fuel cell system and is also the place where hydrogen and oxygen react to output electrical energy. It is a battery group composed of multiple single cells (or basic units) connected in series or in parallel through bipolar plates. Figure 2It is a schematic diagram of the configuration of the basic unit of an existing fuel cell (taking an open cathode proton exchange membrane fuel cell as an example). The entire stack usually includes key components such as a proton exchange membrane, an anode flow channel, and a cathode flow channel (bipolar plate). The proton exchange membrane is located between the anode and the cathode, and mainly outputs electrical energy through an electrochemical reaction. It allows hydrogen ions to pass through but prevents electrons from passing through, thereby generating electrical energy. The bipolar plate (cathode flow channel) mainly supports the stack and provides a reaction and cooling place for oxygen. The anode flow channel mainly provides a reaction place for hydrogen.

[0006] Figure 3 It is a schematic diagram of the configuration of the existing packaged fuel cell stack. A fuel cell stack can be formed by stacking multiple basic units together. In the prior art, most fuel cell stacks adopt a fixed-shape structural design, usually a cubic or rectangular structure. This design method is mainly based on the following considerations: First, in order to ensure the pressure balance between each unit and the airtightness of the system, the cubic structure has a relatively symmetrical force characteristic and good sealing conditions; secondly, traditional bipolar plates mostly adopt a straight flow channel design with a constant cross-section, which is easy to process, manufacture and assemble, and has high consistency and reliability in mass production; finally, the standardized cubic stack structure simplifies the overall layout of the system and the process flow of modular assembly to a certain extent, which is convenient for technology promotion and application.

[0007] However, as fuel cells continue to expand in various application fields, more diversified and flexible requirements are put forward for the overall shape and installation method of the fuel cell stack. The existing cubic or rectangular fuel cell stacks have the following shortcomings:

[0008] 1: Low space utilization;

[0009] In some special application scenarios, such as vehicle chassis, aerospace, and portable devices, the available installation space is often limited by shape and volume. The traditional cubic structure does not fully consider the adaptability of irregular spaces during design, which makes it difficult to achieve optimal use of space during actual installation, and thus makes the overall volume and weight of the system larger, affecting the compactness and performance of the overall device.

[0010] 2: Poor installation adaptability;

[0011] Since the traditional battery stack structure is fixed in a standard three-dimensional form, additional brackets or conversion devices are often required to achieve fixation and installation when facing curved, narrow or irregular installation spaces. This not only increases the complexity of the system, but also brings additional installation difficulties and maintenance costs. In some special occasions, how to achieve efficient matching with the installation space while ensuring the reaction and cooling effects has become a technical problem that needs to be solved urgently.

[0012] 3: Limitations of structural design;

[0013] At present, bipolar plates with a constant cross-section design and straight flow channel structures are mostly used. Although they are helpful for manufacturing and assembly, they limit the diversity of the stack structure to a certain extent. The fixed-shape design is difficult to meet the future requirements for further lightweight and modularization of fuel cell stacks in terms of weight, volume, and shape. In the context of the continuous improvement of system integration and the continuous expansion of application scenarios, how to flexibly control the shape and size of the stack while ensuring airtightness, pressure balance, and thermal management performance has become an important challenge faced by the existing technology.

[0014] Therefore, how to optimize the fuel cell stack has become a key problem that needs to be solved urgently to expand the application scenarios of the fuel cell stack and further improve the space utilization rate. Summary of the Invention

[0015] In view of this, the present invention aims to solve the technical problems such as limited installation space, uneven gas distribution, and local heat accumulation existing in the traditional cube or rectangular structure of the fuel cell stack. The present invention discloses a fuel cell basic unit and a fuel cell stack. By designing a fuel cell basic unit with a variable cross-section bipolar plate, a fuel cell stack with a fan-shaped structure can be formed after stacking multiple basic units, thereby improving the adaptability and installation efficiency of the stack in a special installation space.

[0016] To achieve the above object, the technical solution of the present invention is realized as follows:

[0017] A fuel cell basic unit includes: a variable cross-section bipolar plate having a flow channel that can be sealed and a cross-section with a variable width, which is used to provide support for the entire fuel cell and a place for reaction and cooling for the cathode of the fuel cell;

[0018] A proton exchange membrane is arranged on one side of the variable cross-section bipolar plate and forms an electrochemical reaction region in cooperation with the variable cross-section bipolar plate and the anode flow channel;

[0019] An anode flow channel is arranged on the side of the proton exchange membrane away from the variable cross-section bipolar plate to guide the hydrogen of the anode and provide a reaction place;

[0020] Among them, the width of the flow channel in the variable cross-section bipolar plate is gradually increased along the length direction of the variable cross-section bipolar plate.

[0021] Furthermore, a plurality of flow field grooves are arranged on the variable cross-section bipolar plate, the sizes of the flow field grooves in the length direction decrease in sequence, and the sizes of the flow field grooves in the width direction increase in sequence.

[0022] Furthermore, a sealing groove is formed between two adjacent flow field grooves, the sizes of the sealing grooves in the length direction decrease in sequence, and the sizes of the sealing grooves in the width direction increase in sequence.

[0023] Further, the flow field grooves on the variable cross-section bipolar plate are straight flow channels.

[0024] Further, the variable cross-section bipolar plate is made of a graphite bipolar plate or a metal bipolar plate, and the anode flow channel is made of an alloy material.

[0025] The second object of the present application discloses a fuel cell stack, which includes a plurality of fuel cell basic units as described above. After stacking a plurality of fuel cell basic units, a fuel cell matrix in a fan-shaped structure can be formed.

[0026] Further, an end plate is provided at each end of the fuel cell matrix in the fan-shaped structure. The fuel gas enters the anode flow channel in the fuel cell basic unit through the fuel inlet on the end plate to participate in the reaction, and the remaining fuel gas is discharged through the fuel outlet provided on the end plate.

[0027] Further, the end plate includes an end plate body, and a crimping boss is provided on one side of the end plate body. The crimping boss can be hermetically crimped on the outermost fuel cell basic unit of the fuel cell matrix in the fan-shaped structure, and the fuel inlet and the fuel outlet are provided on the end plate body of one of the end plates.

[0028] Further, a current collector plate is provided on the end plate for collecting and outputting the electric energy generated by the proton exchange membrane.

[0029] Further, the current collector plate is made of an alloy material, the end plate is made of aluminum alloy or epoxy resin, and the fuel gas is hydrogen.

[0030] Compared with the prior art, the fuel cell basic unit and the fuel cell stack of the present invention have the following advantages:

[0031] 1. For the fuel cell basic unit of the present application, by adopting the variable cross-section bipolar plate design, and the flow channel width of the variable cross-section bipolar plate gradually increases along the length direction, so that the fuel gas can form a progressive velocity change during the flow process, which helps the gas to be more evenly distributed in the entire reaction area, improving the reaction efficiency. The variable-width cross-sectional design enables a fan-shaped fuel cell stack to be formed after stacking multiple basic units, breaking through the limitation of the traditional cube structure, so that the stack can better adapt to various irregular installation spaces.

[0032] 2. For the fuel cell stack of the present application, through the modular manufacturing and assembly process, multiple optimized basic units are stacked to form a fan-shaped structure, and further semi-circular and circular configurations can be formed. This not only reduces the production and maintenance costs, but also improves the flexibility and scalability of the system, thereby expanding the application scenarios of the fuel cell stack. Description of the Drawings

[0033] Figure 1 is the working principle diagram of a hydrogen fuel cell;

[0034] Figure 2 is a schematic diagram of the basic unit of an existing hydrogen fuel cell;

[0035] Figure 3 is a schematic diagram of the structure of an existing hydrogen fuel cell after encapsulation;

[0036] Figure 4 is a schematic side view structure diagram of the variable cross-section bipolar plate according to an embodiment of the present invention;

[0037] Figure 5 is a schematic cross-sectional view structure diagram of the variable cross-section bipolar plate according to an embodiment of the present invention;

[0038] Figure 6 is a schematic structure diagram of the fuel cell basic unit according to an embodiment of the present invention;

[0039] Figure 7 is a schematic structure diagram of the fuel cell stack according to an embodiment of the present invention;

[0040] Figure 8 is a schematic structure diagram of the end plate in the fuel cell stack according to an embodiment of the present invention;

[0041] The markings in the figure are indicated as:

[0042] 100 - Membrane electrode assembly; 200 - Anode; 300 - Cathode; 400 - Electric energy; 1 - Variable cross-section bipolar plate; 101 - Flow field groove; 102 - Sealing groove; 2 - Proton exchange membrane; 3 - Anode flow channel; 4 - Current collector plate; 5 - End plate; 501 - End plate body; 502 - Crimping boss; 6 - Fuel inlet; 7 - Fuel outlet. Detailed implementation manners

[0043] Next, the technical solutions in the embodiments of the present application will be clearly described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art belong to the scope of protection of the present application.

[0044] In the description of the present application, it should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments of the present application. For the convenience of description, the sizes of the various parts shown in the drawings are not drawn in actual proportional relationships. Technologies, methods, and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, such technologies, methods, and devices should be regarded as part of the authorization specification. In all the examples shown and discussed here, any specific value should be construed as merely exemplary and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that like reference numerals and letters in the following drawings denote like items, and thus, once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0045] It should be noted that the terms "first", "second", etc. in the description and claims of the present application are used to distinguish similar objects and are not used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the present application can be implemented in an order other than those illustrated or described herein, and the objects distinguished by "first", "second", etc. are generally of the same type and do not limit the number of objects. For example, the first object can be one or multiple. In addition, "and / or" in the description and claims means at least one of the connected objects, and the character " / " generally indicates an "or" relationship between the associated objects before and after.

[0046] It should be noted that in the description of the present application, the orientation or positional relationships indicated by orientation terms such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal", and "top, bottom" are generally based on the orientation or positional relationships shown in the drawings. It is only for the convenience of describing the present application and simplifying the description. Without contrary description, these orientation terms do not indicate and imply that the devices or elements referred to must have a specific orientation or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation on the protection scope of the present application; the orientation terms "inside, outside" refer to the inside and outside relative to the contour of each component itself.

[0047] It should be noted that in this application, the terms "comprise", "include" or any other variant thereof are intended to cover non-exclusive inclusion, such that a process, method, article or apparatus comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or apparatus. Without further limitation, an element defined by the phrase "comprising a..." does not exclude the presence of additional identical elements in the process, method, article or apparatus comprising such element. In addition, it should be pointed out that the scope of the methods and apparatuses in the embodiments of this application is not limited to performing functions in the order shown or discussed, and may also include performing functions in a substantially simultaneous manner or in the reverse order according to the functions involved. For example, the described methods may be performed in an order different from that described, and various steps may be added, omitted, or combined. Additionally, the features described with reference to certain examples may be combined in other examples.

[0048] As Figures 4 to 8 shown, this application discloses a basic fuel cell unit, comprising:

[0049] A variable cross-section bipolar plate 1, having a flow channel that can be sealed and a cross-section with a variable width, for providing support for the entire fuel cell and a place for reaction and cooling for the cathode of the fuel cell;

[0050] A proton exchange membrane 2, disposed on one side of the variable cross-section bipolar plate 1, and cooperating with the variable cross-section bipolar plate 1 and the anode flow channel 3 to form an electrochemical reaction region;

[0051] An anode flow channel 3, disposed on the side of the proton exchange membrane 2 away from the variable cross-section bipolar plate 1, for guiding the hydrogen of the anode and providing a reaction place;

[0052] Wherein, the width of the flow channel in the variable cross-section bipolar plate 1 is gradually increased along the length direction of the variable cross-section bipolar plate 1.

[0053] The fuel cell basic unit disclosed in this application, based on the synergistic effect of the variable cross-section bipolar plate 1, the proton exchange membrane 2, and the anode flow channel 3. When hydrogen enters the reaction area of the fuel cell through the anode flow channel, hydrogen is decomposed into protons and electrons under the action of the catalytic layer above the variable cross-section bipolar plate. The protons diffuse through the proton exchange membrane to the cathode, while the electrons flow through the external circuit to generate current, realizing the output of electrical energy. At the same time, water is generated by the reaction with oxygen at the cathode as the only emission. Among them, the variable cross-section bipolar plate 1 is designed with a flow channel that can achieve sealing, and this flow channel gradually widens from one end to the other in the length direction. This structure not only ensures the supporting role of the bipolar plate as the main load-bearing component in the entire fuel cell, but also provides a stable and sufficient reaction and cooling space for the cathode side. At the same time, its widening design helps to form a progressive flow velocity change during the gas flow process, making the oxygen distribution entering the reaction area more uniform and effective. In addition, by setting a variable-width cross-section, the flow channel width of the bipolar plate gradually increases along the length direction. When multiple basic units are stacked, the overall structure presents a fan shape, thus breaking through the limitations of the traditional cubic structure and achieving an efficient match between the shape of the stack and the installation space.

[0054] The fuel cell basic unit described in this application, by adopting the variable cross-section bipolar plate 1 and the design with a gradually increasing flow channel width, not only realizes the uniform distribution of fuel gas within a single fuel cell basic unit, effectively reduces the fluid flow resistance and pressure loss, but also forms a fan-shaped fuel cell stack by precisely stacking multiple basic units, achieving a geometric shape completely different from the traditional cubic structure. This fan-shaped structure has better adaptability and can be conveniently installed in a curved surface or an irregular space, significantly improving the space utilization rate and the convenience of fixed installation.

[0055] As a preferred example of this application, a plurality of flow field grooves 101 are provided on the variable cross-section bipolar plate 1. The sizes of the flow field grooves 101 in the length direction decrease in sequence, and the sizes of the flow field grooves 101 in the width direction increase in sequence. In the example of this application, a number of flow field grooves 101 are formed by stamping on the variable cross-section bipolar plate 1. These flow field grooves 101 gradually decrease in length dimension along the length direction of the variable cross-section bipolar plate 1, while increasing in width dimension in the width direction. As the flow channel length gradually shortens, the gas flow velocity passing through different cross-sections is smoothly adjusted. And as the width increases, the gas flow area is expanded, making the fluid outer shape of the entire bipolar plate more conform to the structure of the stack and reducing the resistance during the gas flow process.

[0056] This design enables the formation of a gradually changing channel from narrow to wide inside the flow field groove 101. Through this structure, the fuel gas entering the basic unit can experience continuous diffusion and regulation processes in the channel to achieve uniform distribution, thereby effectively reducing local pressure loss and turbulence phenomena, ensuring that fuels such as hydrogen can fully contact the catalyst and complete the reaction when passing through the anode flow channel into the reaction area. At the same time, due to the size change of the flow field groove 101, a continuous temperature gradient is formed, which helps the heat generated during the reaction to be evenly dissipated and keeps the temperature of the reaction area stable.

[0057] As a preferred example of this application, a sealing groove 102 is formed between two adjacent flow field grooves 101. The size of the sealing groove 102 in the length direction decreases successively, and the size of the sealing groove 102 in the width direction increases successively. This setting optimizes the airtightness and hydrodynamic performance of the fuel cell basic unit by arranging the sealing groove 102 between adjacent flow field grooves 101. The size of the sealing groove 102 gradually decreases in the length direction and gradually increases in the width direction, enabling the sealing groove 102 to naturally expand along the distribution direction of the flow field groove 101, forming a gradually changing sealing structure, effectively improving the gas isolation and sealing performance between the flow channels, reducing the risk of local pressure loss and temperature fluctuation. At the same time, when multiple basic units are assembled into a fan-shaped fuel cell stack, the gradually changing design of the sealing groove 102 not only enhances the sealing and mechanical stability between the units, making the overall structure more compact and stable, but also constructs continuous gas flow and heat transfer channels inside the stack, achieving balanced temperature distribution and efficient cooling effect, and further improving the energy conversion efficiency and fuel utilization rate of the entire system.

[0058] As a preferred example of the present application, the flow field channels 101 on the variable cross-section bipolar plate 1 are straight flow channels. In the example of the present application, the flow field channels 101 on the variable cross-section bipolar plate adopt a straight flow channel design. The flow field channels 101 are straight channels, so that the channels maintain a straight extension on the basis of gradually decreasing in the length direction and gradually increasing in the width direction, so as to realize the uniform and stable flow of the fuel gas in a fixed direction along the leading edge of the electrochemical reaction zone. The straight flow channel structure enables the fuel (such as hydrogen) to accelerate in the gradually shrinking cross-section and fully diffuse in the gradually expanding area when passing through the channel, ensuring the balance of gas flow velocity and pressure, reducing the local pressure loss and the turbulence effect. At the same time, the unified linear structure of the straight channel helps to simplify the manufacturing and assembly processes, enhance the sealing performance and mechanical bonding effect between the bipolar plate and the adjacent components. When multiple basic units are stacked at a predetermined angle to form a fan-shaped fuel cell stack, the straight flow channel can achieve seamless connection of the fluid channels between the units, forming a continuous gas transmission path and a balanced temperature field distribution, so that the entire fuel cell stack can ensure that the fuel participates in the reaction sufficiently, the heat is dissipated in time, and the gas flows stably and smoothly during the high-load and long-time continuous operation process.

[0059] The variable cross-section bipolar plate with straight flow channels can enable the fuel gas to achieve precise guidance and balanced diffusion when passing through the straight channels, which not only simplifies the manufacturing process and reduces the production cost, but also enhances the system sealing performance and mechanical fixation, improves the thermal management effect, and finally enables the fuel cell to exhibit excellent stability and durability under high-load and long-time operation conditions.

[0060] As a preferred example of the present application, the variable cross-section bipolar plate 1 is made of a graphite bipolar plate or a metal bipolar plate, and the anode flow channel 3 is made of an alloy material. In the example of the present application, for the variable cross-section bipolar plate 1, high-performance graphite or metal products are selected as its manufacturing materials. By utilizing their excellent electrical conductivity, corrosion resistance, and mechanical strength, the bipolar plate can form a finely designed flow field groove 101 and a sealing groove 102 while providing a stable structural support. At the same time, the anode flow channel 3 is made of an alloy material, and its characteristics of light weight, high strength, high temperature resistance, and corrosion resistance ensure good flow guiding effect and reaction conditions when hydrogen enters the electrochemical reaction zone. Each component forms a complete and efficient reaction system through precise fitting and sealing treatment. By combining the variable cross-section bipolar plate 1 made of graphite or metal with the anode flow channel 3 made of an alloy material, the present application can significantly improve the electrochemical reaction efficiency of the fuel cell basic unit. Its optimized flow field design enables the fuel gas to participate in the reaction in the best state after gradually accelerating and uniformly diffusing in the straight channel, not only improving the fuel utilization rate and energy conversion efficiency, but also reducing the manufacturing cost and maintenance difficulty through the selection of lightweight and high-strength materials, meeting the reliable use of fuel cells in special installation spaces and complex working environments. In the example of the present application, the variable cross-section bipolar plate 1 can be made of metal materials such as stainless steel, titanium alloy, and aluminum alloy, and the anode flow channel 3 can be made of alloy materials such as stainless steel alloy, titanium alloy, aluminum alloy, and nickel-based alloy by molding.

[0061] The present application also discloses a fuel cell stack, which includes a plurality of fuel cell basic units. After the plurality of fuel cell basic units are stacked, a fuel cell matrix in a fan-shaped structure can be formed. The fuel cell stack of the present application forms a fan-shaped fuel cell matrix by precisely stacking and assembling a plurality of optimized fuel cell basic units at a predetermined angle and in a predetermined order. Each basic unit includes a bipolar plate with a variable cross-section structure, a proton exchange membrane 2, and an anode flow channel 3. The variable cross-section bipolar plate 1 realizes the geometric characteristics that the fluid channel gradually decreases in the length direction and gradually increases in the width direction by using the gradient design of the flow field groove 101 and the sealing groove 102, so that the fuel gas entering each unit can be evenly distributed after continuous diffusion and adjustment during the flow guiding process, and seamless connection of gas and heat between each unit is ensured through strict sealing and mechanical connection, thereby building a continuous and efficient electrochemical reaction and thermal management closed-loop system inside the entire fuel cell stack. At the same time, in the example of the present application, a fan-shaped fuel cell matrix is formed by stacking a plurality of fuel cell basic units, and on this basis, semi-circular and circular fuel cell stack configurations can be further formed to meet the requirements of various non-standard or restricted installation spaces, thereby expanding the application scenarios of the fuel cell stack.

[0062] This setting forms a sector structure by stacking multiple optimized basic units, effectively improving problems such as limited installation space, uneven gas distribution, and local heat accumulation faced by traditional cubic or rectangular fuel cell stacks. At the same time, since the sector structure can be flexibly converted into a semi-circular or circular configuration, this design fully meets the requirements of various non-standard installation spaces, and reduces production and maintenance costs through modular manufacturing and assembly processes. As a result, it not only improves fuel utilization and power conversion efficiency, but also significantly enhances the stability and durability of the overall system under high load and long-term continuous operation conditions.

[0063] As a preferred example of this application, a end plate 5 is provided at each end of the fuel cell matrix with a sector structure. The fuel gas enters the anode flow channel 3 in the fuel cell basic unit through the fuel inlet 6 on the end plate 5 to participate in the reaction, and the residual fuel gas is discharged through the fuel outlet 7 provided on the end plate 5. A current collector plate 4 is provided on the end plate 5 to collect and output the electric energy generated by the proton exchange membrane 2. In the example of this application, the fuel gas is hydrogen, which has a high energy density and is pollution-free. The working principle of the fuel cell stack of the present invention is as follows: air and hydrogen are respectively introduced at the cathode and the anode. The air directly flows through the variable cross-section bipolar plate 1 to ensure the reaction and cooling of the fuel cell; the hydrogen enters through the fuel inlet 6 on the end plate 5 and then enters each anode flow channel 3 for an electrochemical reaction, and is then discharged through the fuel outlet 7 on the end plate 5. The electric energy generated by each proton exchange membrane 2 is collected and output by the current collector plate 4.

[0064] In this application, by providing an end plate 5 at each of the opposite ends of the fuel cell matrix that can form a sector structure after stacking multiple fuel cell basic units, it not only serves as a structural support, but also integrates the functions of the inlet and outlet of the fuel gas, ensuring the uniform distribution and orderly discharge of hydrogen inside the fuel cell stack, reducing the gas flow resistance, and improving the reaction efficiency.

[0065] As a preferred example of this application, the end plate 5 includes an end plate body 501, and a crimping boss 502 is provided on one side of the end plate body 501. The crimping boss 502 can be hermetically crimped on the outermost fuel cell basic unit of the fuel cell matrix with a sector structure. The fuel inlet 6 and the fuel outlet 7 are provided on the end plate body 501 of one end plate 5. In the example of this application, the end plate 5 is designed to be composed of an end plate body 501 and a crimping boss 502 provided on one side thereof. During the assembly process, the crimping boss 502 can be precisely hermetically crimped on the outermost fuel cell basic unit of the fuel cell matrix with a sector structure, ensuring the sealing and structural stability of the entire fuel cell stack; at the same time, the fuel inlet 6 and the fuel outlet 7 are cleverly provided on the end plate body 501. Such a layout not only facilitates the input and output of the fuel gas, but also effectively simplifies the pipeline system of the fuel cell stack.

[0066] This setting not only ensures the orderly flow of fuel gas by further optimizing the structure of the end plate 5, but also provides the necessary pressure through the crimping boss 502 to ensure the close contact between the basic fuel cell units, simplifies the structure of the stack, reduces the complexity of external pipelines and connection points, and decreases the likelihood of failures. At the same time, this optimized design enables the fuel cell stack to have better adaptability and flexibility while maintaining high performance, and can more easily meet the requirements of different application scenarios.

[0067] As a preferred example of this application, the current collector plate 4 is made of an alloy material with high strength and light weight, and the end plate 5 is made of aluminum alloy or epoxy resin with relatively high strength and light weight. In the example of this application, the current collector plate 4 can be made of high-strength and light-weight alloy materials such as titanium alloy or aluminum alloy. By selecting high-strength and light-weight alloy materials such as titanium alloy or aluminum alloy to manufacture the current collector plate 4, the high-strength performance improves the load-bearing capacity of the current collector plate 4, enabling it to withstand various mechanical stresses during the operation of the stack and ensuring the stable operation of the stack. The light-weight performance reduces the weight of the current collector plate 4, and thus reduces the weight of the entire stack, improving the portability and mobility of the stack. Moreover, the good electrical conductivity of the alloy material ensures the efficient transmission of electrical energy, improving the output power and efficiency of the stack. The end plate 5 is made of aluminum alloy or epoxy resin material to meet the structural support and sealing requirements of the stack.

[0068] This setting realizes the comprehensive improvement of the fuel cell stack in terms of performance, weight, stability, and durability by optimizing the material selection of the current collector plate 4 and the end plate 5.

[0069] The fuel cell stack disclosed in the present invention realizes the fan-shaped structure of the fuel cell stack by designing the variable cross-section bipolar plate 1, thus facilitating the further realization of the configurations of fan-shaped, semi-circular, and circular stacks, significantly improving the adaptability and installation efficiency of the stack in irregular spaces such as vehicle chassis and aerospace equipment. At the same time, through the optimization of the gradual change of the sizes of the flow field grooves and the sealing grooves, the uniform distribution of fuel gas and pressure balance are achieved, reducing the flow resistance and local turbulence and temperature fluctuations. Combining with the straight-line extension characteristics of the straight flow channel grooves simplifies the manufacturing process and enhances the gas flow stability.

[0070] The embodiments of this application are described above in conjunction with the accompanying drawings. Without conflict, the embodiments and the features in the embodiments in this application can be combined with each other. This application is not limited to the above specific embodiments. The above specific embodiments are merely illustrative and not restrictive. Under the inspiration of this application, those of ordinary skill in the art can also make many forms without departing from the purpose of this application and the scope protected by the claims, and all of them belong to the protection scope of this application.

Claims

1. A fuel cell basic unit, characterized in that: include: A variable cross-section bipolar plate (1) having a flow channel that can be sealed and a cross-section of variable width, used to provide support for the entire fuel cell and a place for reaction and cooling of the fuel cell cathode; A proton exchange membrane (2) is arranged on one side of the variable cross-section bipolar plate (1) and cooperates with the variable cross-section bipolar plate (1) and the anode flow channel (3) to form an electrochemical reaction area; an anode flow channel (3), arranged on a side of the proton exchange membrane (2) away from the variable cross-section bipolar plate (1), for guiding hydrogen gas at the anode and providing a reaction site; Wherein, the width of the flow channel in the variable cross-section bipolar plate (1) is arranged to gradually increase along the length direction of the variable cross-section bipolar plate (1).

2. The fuel cell basic unit according to claim 1, characterized in that: A plurality of flow field grooves (101) are arranged on the variable cross-section bipolar plate (1), wherein the size of the flow field grooves (101) in the length direction decreases successively, and the size of the flow field grooves (101) in the width direction increases successively.

3. The fuel cell basic unit according to claim 2, characterized in that: A sealing groove (102) is formed between two adjacent flow field grooves (101), and the size of the sealing groove (102) in the length direction decreases successively, while the size of the sealing groove (102) in the width direction increases successively.

4. The fuel cell basic unit according to claim 2, characterized in that: The flow field grooves (101) on the variable cross-section bipolar plate (1) are straight flow channel grooves.

5. The fuel cell basic unit according to claim 1, characterized in that: The variable cross-section bipolar plate (1) is made of a graphite bipolar plate or a metal bipolar plate, and the anode flow channel (3) is made of an alloy material.

6. A fuel cell stack, characterized in that: It comprises a plurality of fuel cell basic units as claimed in any one of claims 1 to 5, and a plurality of fuel cell basic units can form a fuel cell matrix with a fan-shaped structure after being stacked.

7. The fuel cell stack according to claim 6, characterized in that: An end plate (5) is provided at each end of the fan-shaped fuel cell matrix, and fuel gas enters the anode flow channel (3) in the fuel cell basic unit through a fuel inlet (6) on the end plate (5) to participate in the reaction, and residual fuel gas is discharged through a fuel outlet (7) provided on the end plate (5).

8. The fuel cell stack according to claim 7, characterized in that: The end plate (5) comprises an end plate body (501), a crimping boss (502) is arranged on one side of the end plate body (501), and the crimping boss (502) can be sealed and crimped to the outermost fuel cell basic unit of the fuel cell matrix of the fan-shaped structure, and the fuel inlet (6) and the fuel outlet (7) are arranged on the end plate body (501) of one of the end plates (5).

9. The fuel cell stack according to claim 7, characterized in that: A current collecting plate (4) is arranged on the end plate (5) for collecting and outputting the electric energy generated by the proton exchange membrane (2).

10. The fuel cell stack according to claim 9, characterized in that: The current collecting plate (4) is made of alloy material, the end plate (5) is made of aluminum alloy or epoxy resin, and the fuel gas is hydrogen.

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