Fuel cells and their systems

Abstract

The present invention provides a fuel cell and a fuel cell system. The fuel cell comprises: a proton exchange membrane, an anode gas diffusion layer, which is located on the first side of the proton exchange membrane; a cathode gas diffusion layer, which is located on the second side of the proton exchange membrane; a first bipolar plate, which is located on the first side of the anode gas diffusion layer; and a second bipolar plate, which is located on the second side of the cathode gas diffusion layer; wherein the first side is opposite to the second side; the anode gas diffusion layer comprises a self-supporting membrane, which is formed by an amorphous porous carbon molecular sieve, which comprises a stacked porous carbon molecular sieve with multiple gradient pore sizes, and the porous carbon molecular sieves with multiple gradient pore sizes can separate nitrogen and hydrogen.

Description

Technical Field

[0001] The present invention belongs to the field of membrane electrode technology, and in particular relates to a fuel cell and a system thereof. Background Art

[0002] As an important component of the future energy system, hydrogen energy has great development prospects in the fields of industry and transportation. However, the transportation and storage of hydrogen are the key problems that restrict the promotion and application of hydrogen energy technology. Ammonia has the advantages of high energy density, easy liquefaction, easy transportation, low cost, high safety, and non-explosion. It is the best carrier of hydrogen. Therefore, indirect ammonia fuel cells have also been proposed as an effective solution for hydrogen energy vehicles. The fuel cell system is mainly an integrated system of an ammonia decomposer and a proton exchange membrane fuel cell. Ammonia is first decomposed into hydrogen and nitrogen through a decomposition reactor, and then the decomposed hydrogen is introduced into the proton exchange membrane fuel cell. However, the main problem for this system is that the current commercial proton exchange membrane fuel cells are mainly used as direct pure hydrogen, and their nitrogen tolerance is limited. Therefore, when the mixed gas from the ammonia reactor is directly introduced, the performance of the proton exchange membrane fuel cell will decrease due to the presence of nitrogen.

[0003] The existing technology usually requires adding an additional hydrogen purification device and a hydrogen buffer device between the ammonia decomposer and the proton exchange membrane fuel cell to achieve the purpose of hydrogen and nitrogen separation, such as the indirect ammonia mixer fuel cell system disclosed in the CN216958124U patent.

[0004] However, this type of system usually requires a lot of equipment, which is placed in a dispersed manner, occupies a large area, and is costly, resulting in a low level of integration in hydrogen-powered vehicles. Summary of the invention

[0005] The present invention provides a fuel cell and a system thereof, which can solve the technical problems that the fuel cell system provided by the related art requires a lot of equipment, the equipment is placed in a dispersed manner, occupies a large area, has a high cost, and leads to a low integration level of hydrogen energy vehicles.

[0006] The technical solution provided by the present invention is as follows:

[0007] In one aspect, a fuel cell is provided, the fuel cell comprising:

[0008] Proton exchange membrane,

[0009] an anode gas diffusion layer, located on a first side of the proton exchange membrane;

[0010] a cathode gas diffusion layer, located on the second side of the proton exchange membrane;

[0011] a first bipolar plate located on a first side of the anode gas diffusion layer;

[0012] a second bipolar plate located on a second side of the cathode gas diffusion layer;

[0013] wherein the first side is opposite to the second side;

[0014] The anode gas diffusion layer includes a self-supporting membrane, which is formed by an amorphous porous carbon molecular sieve. The amorphous porous carbon molecular sieve includes a stacked porous carbon molecular sieve with multiple gradient pore sizes, and the porous carbon molecular sieve with multiple gradient pore sizes can separate nitrogen and hydrogen.

[0015] In an optional embodiment of the present invention, the porous carbon molecular sieves of multiple gradient pore sizes include a porous carbon molecular sieve of a starting gradient pore size, a porous carbon molecular sieve of a transition gradient pore size, and a porous carbon molecular sieve of a final gradient pore size;

[0016] The porous carbon molecular sieve with the initial gradient pore size is close to one end of the first bipolar plate, and the porous carbon molecular sieve with the final gradient pore size is close to one end of the proton exchange membrane. The pore size of the initial gradient pore size decreases successively along the direction of the final gradient pore size.

[0017] In an optional embodiment of the present invention, the final gradient pore size is between 0.289 nm and 0.364 nm, and the initial gradient pore size and the transition gradient pore size are both larger than 0.364 nm.

[0018] In an optional embodiment of the present invention, the self-supporting membrane comprises a hollow carbon fiber membrane or a substrate-supported composite membrane.

[0019] In an optional embodiment of the present invention, the amorphous porous carbon molecular sieve includes graphene or ordered mesoporous carbon.

[0020] In an optional embodiment of the present invention, the selectivity of the amorphous porous carbon molecular sieve to nitrogen and hydrogen is greater than 70%.

[0021] On the other hand, a fuel cell system is provided, the fuel cell system comprising any of the above-mentioned fuel cells and an ammonia decomposer;

[0022] One end of the ammonia decomposer is used to connect with the ammonia generator for ammonia to enter, and the other end produces nitrogen and hydrogen mixed gas, which is connected to the fuel cell, and the nitrogen and hydrogen mixed gas enters the fuel cell.

[0023] In an optional embodiment of the present invention, a condenser is further included, and the condenser is located between the ammonia decomposer and the fuel cell.

[0024] In an optional embodiment of the present invention, it further comprises a first valve and a second valve, wherein the first valve is located between the ammonia decomposer and the fuel cell, and the second valve is located between the condenser and the fuel cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The above and other objects, features and advantages of the present disclosure will become more apparent through a more detailed description of exemplary embodiments of the present disclosure in conjunction with the accompanying drawings, wherein like reference numerals generally represent like components throughout the exemplary embodiments of the present disclosure.

[0026] Figure 1 A schematic diagram of the fuel cell system structure is shown.

[0027] 1-proton exchange membrane, 2-cathode gas diffusion layer, 3-anode gas diffusion layer, 4-condenser, 5-ammonia decomposer, 6-first valve, 7-second valve, 8-first bipolar plate, 9-second bipolar plate. DETAILED DESCRIPTION

[0028] Embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to make the present disclosure more thorough and complete, and to fully convey the scope of the present disclosure to those skilled in the art.

[0029] As used herein, the term "including" and its variations mean open inclusion, i.e., "including but not limited to". Unless otherwise stated, the term "or" means "and / or". The term "based on" means "based at least in part on". The terms "an example embodiment" and "an embodiment" mean "at least one example embodiment". The term "another embodiment" means "at least one additional embodiment". The terms "first", "second", etc. may refer to different or the same objects. Other explicit and implicit definitions may also be included below.

[0030] The fuel cell and system provided by the present invention can be used for separation of nitrogen and hydrogen, and can be directly used in conjunction with an ammonia decomposer system, thereby solving the problem of performance degradation of ammonia fuel cells indirectly caused by nitrogen, and the system has a high degree of integration.

[0031] In one aspect, the present invention provides a fuel cell, see Figure 1The fuel cell includes: a proton exchange membrane 1, an anode gas diffusion layer 3, which is located on the first side of the proton exchange membrane 1; a cathode gas diffusion layer 2, which is located on the second side of the proton exchange membrane 1; a first bipolar plate, which is located on the first side of the anode gas diffusion layer 3; a second bipolar plate, which is located on the second side of the cathode gas diffusion layer 2; wherein the first side is opposite to the second side; the anode gas diffusion layer 3 includes a self-supporting membrane, and the self-supporting membrane is formed by an amorphous porous carbon molecular sieve, and the amorphous porous carbon molecular sieve includes a stacked porous carbon molecular sieve with multiple gradient pore sizes, and the porous carbon molecular sieves with multiple gradient pore sizes can separate nitrogen and hydrogen.

[0032] The anode side of the fuel cell provided by the present invention uses a carbon-based material membrane (self-supporting membrane) to replace the original anode diffusion layer. The carbon-based material membrane is an amorphous porous carbon molecular sieve. The amorphous porous carbon molecular sieve includes a porous carbon molecular sieve with multiple gradient pore sizes arranged in a stacked manner. The porous carbon molecular sieves with multiple gradient pore sizes can separate nitrogen and hydrogen, so that hydrogen can more easily penetrate into the surface of the anode catalyst layer to cause the proton exchange membrane 1 to undergo a proton reaction, while nitrogen is intercepted by the porous carbon molecular sieves with multiple gradient pore sizes because the molecular diameter is larger than that of hydrogen. Thus, the separation of hydrogen and nitrogen is achieved by using the molecular sieve separation mechanism of gas diffusion, which solves the effect of the presence of nitrogen on the performance degradation of the fuel cell. At the same time, the amorphous porous carbon molecular sieve membrane used in the present invention itself has the characteristics of conductivity and mechanical strength, so it can fully assume the function of the original anode diffusion layer. Therefore, in the present invention, the hydrogen-nitrogen separation function can be added on the basis of the original anode diffusion layer function, and the fuel cell of the present invention can be directly used in conjunction with the ammonia decomposition reactor system, saving additional membrane separator equipment, improving the integration of the system and reducing the use cost.

[0033] It should be noted that the proton exchange membrane 1, the anode gas diffusion layer 3, the cathode gas diffusion layer 2, the first bipolar plate and the second bipolar plate provided by the present invention are consistent with those in the related art, and the embodiments of the present invention will not be described in detail here.

[0034] According to an optional embodiment of the present invention, the porous carbon molecular sieves with multiple gradient pore sizes include a porous carbon molecular sieve with an initial gradient pore size, a porous carbon molecular sieve with a transition gradient pore size, and a porous carbon molecular sieve with a final gradient pore size.

[0035] The porous carbon molecular sieve with the initial gradient pore size is close to one end of the first bipolar plate, and the porous carbon molecular sieve with the final gradient pore size is close to one end of the proton exchange membrane. The pore sizes of the initial gradient pore size decrease successively along the direction of the final gradient pore size.

[0036] The porous carbon molecular sieve with initial gradient pore size, the porous carbon molecular sieve with transition gradient pore size and the porous carbon molecular sieve with final gradient pore size in the present invention may all include multiple layers of porous carbon molecular sieves. The multiple layers of porous carbon molecular sieves in the present invention are interconnected, and the pore size of the porous carbon molecular sieve decreases in sequence along the final gradient pore size direction, so that the step-by-step separation of nitrogen and hydrogen can be achieved, thereby improving the separation efficiency of nitrogen and hydrogen.

[0037] According to an optional embodiment of the present invention, the initial gradient pore size and the transition gradient pore size are greater than 0.364 nm, and the final gradient pore size is between 0.289 nm and 0.364 nm. Illustratively, the pore size of the porous carbon molecular sieve with a final gradient pore size can be 0.290nm, 0.291nm, 0.292nm, 0.293nm, 0.294nm, 0.295nm, 0.296nm, 0.297nm, 0.298nm, 0.299nm, 0.305nm, 0.307nm, 0.309nm, 0.310nm, 0.311nm, 0.314nm, 0.321nm, 0.322nm, 0.325nm, 0.327nm, 0.329nm, 0.330nm, 0.335nm, 0.339nm, 0.340nm, 0.356nm, 0.358nm, 0.360nm, 0.362nm or 0.364nm, etc. It should be noted that the porous carbon molecular sieve of each pore size can be a layer, which can improve the separation efficiency of hydrogen and nitrogen.

[0038] In the present disclosure, the porous carbon molecular sieve with a small pore size is connected to the porous molecular sieve with a large pore size.

[0039] According to an optional embodiment of the present invention, the self-supporting membrane comprises a hollow carbon fiber membrane or a base-supported composite membrane.

[0040] According to an optional embodiment of the present invention, the amorphous porous carbon molecular sieve includes graphene or ordered mesoporous carbon.

[0041] According to an optional embodiment of the present invention, the selectivity of the amorphous porous carbon molecular sieve to nitrogen and hydrogen is greater than 70%.

[0042] On the other hand, the present invention further provides a fuel cell system, which includes any one of the above-mentioned fuel cells and an ammonia decomposer 5 .

[0043] One end of the ammonia decomposer 5 is connected to the fuel cell, and the other end is used to connect to the nitrogen and hydrogen mixer.

[0044] The fuel cell system provided by the present invention can be directly connected to the ammonia decomposer 5, and ammonia is decomposed to generate nitrogen and hydrogen. The nitrogen and hydrogen mixed gas is dispersed through the anode gas dispersion layer of the fuel cell of the present invention, and the dispersed hydrogen can directly react with the proton exchange membrane 1, and the nitrogen can be discharged from the air inlet of the mixer. The present invention realizes the separation of hydrogen and nitrogen, and solves the influence of the presence of nitrogen on the performance degradation of the fuel cell.

[0045] According to an optional embodiment of the present invention, a condenser 46 is further included, and the condenser 46 is located between the ammonia decomposer 5 and the fuel cell.

[0046] The condenser 46 is provided to condense the nitrogen and hydrogen mixture decomposed by the ammonia decomposer 5 to the temperature used by the fuel cell and then introduced into the fuel cell.

[0047] According to an optional embodiment of the present invention, a first valve 6 and a second valve 7 are further included. The first valve 6 is located between the ammonia decomposer 5 and the condenser 46, and the second valve 7 is located between the condenser 46 and the fuel cell.

[0048] The content of the nitrogen and hydrogen mixed gas entering the condenser 46 can be controlled by setting the first valve 6, and the content of the nitrogen and hydrogen mixed gas entering the fuel cell can be controlled by setting the second valve 7.

[0049] The embodiments of the present disclosure have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The selection of terms used herein is intended to best explain the principles of the embodiments, practical applications, or technical improvements in the market, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. A fuel cell, characterized in that: The fuel cell comprises: Proton exchange membrane, an anode gas diffusion layer, located on a first side of the proton exchange membrane; a cathode gas diffusion layer, located on the second side of the proton exchange membrane; a first bipolar plate located on a first side of the anode gas diffusion layer; a second bipolar plate located on a second side of the cathode gas diffusion layer; wherein the first side is opposite to the second side; The anode gas diffusion layer comprises a self-supporting membrane, wherein the self-supporting membrane is formed by an amorphous porous carbon molecular sieve, wherein the amorphous porous carbon molecular sieve comprises a stacked porous carbon molecular sieve having a plurality of gradient pore sizes, wherein the porous carbon molecular sieve having a plurality of gradient pore sizes can separate nitrogen and hydrogen; The porous carbon molecular sieves with multiple gradient pore sizes include a porous carbon molecular sieve with a starting gradient pore size, a porous carbon molecular sieve with a transition gradient pore size, and a porous carbon molecular sieve with a final gradient pore size; The porous carbon molecular sieve with the initial gradient pore size is close to one end of the first bipolar plate, and the porous carbon molecular sieve with the final gradient pore size is close to one end of the proton exchange membrane, and the pore size of the initial gradient pore size decreases in sequence along the direction of the final gradient pore size; The final gradient pore size is between 0.289 nm and 0.364 nm, and the initial gradient pore size and the transition gradient pore size are both larger than 0.364 nm.

2. The fuel cell according to claim 1, characterized in that The self-supporting membrane includes a hollow carbon fiber membrane or a base-supported composite membrane.

3. The fuel cell according to claim 1, characterized in that The amorphous porous carbon molecular sieve includes graphene or ordered mesoporous carbon.

4. The fuel cell according to claim 1, characterized in that The selectivity of the amorphous porous carbon molecular sieve to nitrogen and hydrogen is greater than 70%.

5. A fuel cell system, characterized in that: The fuel cell system comprises the fuel cell and the ammonia decomposer according to any one of claims 1 to 4; One end of the ammonia decomposer is used to connect with the ammonia generator for ammonia to enter, and the other end produces nitrogen and hydrogen mixed gas, which is connected to the fuel cell, and the nitrogen and hydrogen mixed gas enters the fuel cell.

6. The fuel cell system according to claim 5, characterized in that: Also included is a condenser located between the ammonia decomposer and the fuel cell.

7. The fuel cell system according to claim 6, characterized in that: The invention also includes a first valve and a second valve, wherein the first valve is located between the ammonia decomposer and the fuel cell, and the second valve is located between the condenser and the fuel cell.

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