Integral solid oxide fuel cell / electrolytic cell stack

Abstract

The invention discloses a design, manufacturing and use method of an integral solid oxide fuel cell / electrolytic cell stack. The stack is formed by integrating integral solid oxide fuel cell / electrolytic cell units through a connector structure; the integral solid oxide fuel cell / electrolytic tank unit comprises an internal supporting thin-wall structure, an external thin-wall sealing structure, an external supporting structure, a fuel electrode coating, an oxygen electrode coating and a current collecting coating structure; the internal supporting thin-wall structure, the external thin-wall sealing structure, the external supporting structure and the connecting body are of an integrated structure and can be integrally formed through the additive manufacturing technology. The internal support thin-wall structure is in the shape of a three-period minimal curved surface with thickness and is used as an electrolyte of the electric pile; the internal supporting thin-wall structure and the external thin-wall sealing structure at least form a cavity; the cavity is a gas flow channel of fuel gas or oxygen-enriched gas and is provided with at least one gas inlet and at least one gas outlet; the fuel electrode coating and the oxygen electrode coating cover the surfaces of the two sides of the internal supporting thin-wall structure respectively; the collector coating structure covers the surface of the fuel electrode coating and can finally form a communicated circuit with an external electric appliance or a power supply. According to the integral galvanic pile, the use of parts is reduced, and the compactness, the light weight and the stability of the galvanic pile are improved; and the manufacturing process flow is simplified, and the manufacturing efficiency and the on-site manufacturing capability are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fuel cell / electrolyser stack, in particular to a design and manufacturing method of a monolithic solid oxide fuel cell / electrolyser stack with high compactness and high lightness. BACKGROUND

[0002] Solid oxide fuel cell / electrolyser is an energy conversion technology. Depending on the operating conditions, two different modes of operation, fuel cell and electrolyser, can be achieved. In fuel cell mode, chemical energy of fuel gas containing carbon, oxygen or hydrogen can be converted into electricity to power electrical devices; in electrolyser mode, water or carbon dioxide can be electrolyzed to produce gas containing carbon, oxygen or hydrogen. Compared with existing similar clean energy technologies, solid oxide fuel cell / electrolyser technology has higher energy conversion efficiency.

[0003] In practical applications, multiple single solid oxide fuel cell / electrolyser cells are integrated with metal connectors, sealing sheets and other components by welding to form a solid oxide fuel cell / electrolyser stack (referred to as stack) to obtain the required power. High-power solid oxide fuel cell / electrolyser stacks can be connected to wind power stations, solar power stations, etc. to convert electricity into fuel gas and store it when there is excess electricity. When electricity is in short supply, fuel gas can be converted into electricity through fuel cell mode to power the grid.

[0004] However, the integration of the stack is very complex, requiring the use of multiple parts and technologies to ensure the stack's air tightness and good electronic conductivity under high temperature operating conditions. This makes the stack's material and manufacturing costs higher than existing similar technologies. In addition, the use of a large number of parts increases the mass and volume of the stack, reducing the specific power of the stack. Oxidation and corrosion of some metal components under long-term high temperature operating conditions can also cause degradation of the stack's performance. SUMMARY

[0005] Therefore, the present application evolves the traditional two-dimensional planar structure of the cell into a three-dimensional structure. One of the purposes of the present application is to design a monolithic solid oxide fuel cell / electrolyser stack, which on the one hand reduces the use of parts, reduces the manufacturing cost of the stack, and on the other hand improves the lightness and compactness of the stack, and improves the specific power and long-term performance stability of the stack. The second purpose of the present application is to provide a manufacturing method and a use method of a monolithic solid oxide fuel cell / electrolyser stack.

[0006] The present application achieves the above-mentioned purposes by the following method:

[0007] The first aspect of the present application provides a design of a monolithic solid oxide fuel cell / electrolysis cell stack, the stack is integrated by monolithic solid oxide fuel cell / electrolysis cell units through a connector structure. The monolithic solid oxide fuel cell / electrolysis cell unit includes an internal support thin-walled structure, an external thin-walled sealing structure, an external support structure, a fuel electrode coating, an oxygen electrode coating, and a current collector coating structure. The internal support thin-walled structure, the external thin-walled sealing structure, the external support structure, and the connector are a monolithic structure and a monolithic component. The internal support thin-walled structure is a three-periodic minimal surface with a thickness, serving as an electrolyte of the stack. The internal support thin-walled structure and the external thin-walled sealing structure form at least one cavity. The cavity is a gas flow channel for fuel gas or oxygen-rich gas, and has at least one gas inlet and at least one gas outlet. The fuel electrode coating and the oxygen electrode coating cover the two side surfaces of the internal support thin-walled structure, respectively. The current collector coating structure covers the surfaces of the fuel electrode coating and the oxygen electrode, and can finally form a communication circuit with an external electrical device or power source. The external support structure is connected to the connector, and the external support structure has at least one gas outlet.

[0008] The stack of the present application has the following structural advantages:

[0009] (1) The structural components of the monolithic solid oxide fuel cell / electrolysis cell stack include an internal support thin-walled structure, an external thin-walled sealing structure, an external support structure, and a connector, which are a monolithic structure and can be integrally formed. Compared with existing stacks, the monolithic stack avoids the assembly and welding of additional parts, simplifies the process flow, reduces material costs, and reduces overall costs.

[0010] (2) The monolithic solid oxide fuel cell / electrolysis cell stack reduces the use of additional parts, improves the lightweight and compactness of the stack, and enhances the application prospects in mobile devices and vehicles.

[0011] (3) The monolithic solid oxide fuel cell / electrolysis cell stack can adjust the number, size, and appearance of the solid oxide fuel cell / electrolysis cell units according to application requirements, and has high design flexibility.

[0012] (4) The monolithic solid oxide fuel cell / electrolysis cell stack greatly simplifies the process flow, reduces the requirements for manufacturing sites and equipment, improves manufacturing flexibility, and enhances the application capability in on-site manufacturing scenarios.

[0013] The second aspect of the present application provides a manufacturing method and a use method of a monolithic solid oxide fuel cell / electrolysis cell stack, including the following steps:

[0014] (1) Use additive manufacturing technology including but not limited to light-cured additive manufacturing technology, adhesive jet forming additive manufacturing technology and selective laser sintering technology to integrally manufacture the internal support thin-walled structure, the external thin-walled sealing structure, the external support structure and the connecting body structure of the monolithic solid oxide fuel cell / electrolysis cell stack. The internal support thin-walled structure is the electrolyte of the monolithic solid oxide fuel cell / electrolysis cell stack, which is composed of a solid oxide material with ionic conductivity or proton conductivity. The function of the electrolyte is to isolate the fuel gas and the oxygen-rich gas on both sides and serve as a transmission path for ions or protons.

[0015] (2) Use chemical or physical deposition methods including but not limited to dip coating, chemical vapor deposition and physical vapor deposition to coat the fuel electrode material and the oxygen electrode material on the surfaces of the internal support thin-walled structure of the stack on both sides with slurry, liquid phase or gas phase as the carrier.

[0016] (3) Use chemical or physical deposition methods including but not limited to dip coating, chemical vapor deposition and physical vapor deposition to coat the current collecting material on the surfaces of the fuel electrode coating and the oxygen electrode coating with slurry, liquid phase or gas phase as the carrier.

[0017] (4) Introduce fuel gas including but not limited to hydrogen, methane or carbon monoxide from the gas inlet of the fuel electrode gas flow channel, expose the oxygen electrode to an oxygen or air atmosphere, and under the condition of greater than or equal to 500 degrees Celsius, an electrochemical reaction occurs, chemical energy is converted into electrical energy, and the external power consumer is powered, which is the working mode of the fuel cell. The by-products generated by the fuel electrode, including water vapor and carbon dioxide, are discharged from the exhaust port of the fuel electrode gas flow channel and collected by external devices.

[0018] (5) Connect the external power source to the fuel electrode and the oxygen electrode, apply power, introduce water vapor or carbon dioxide into the gas flow channel of the fuel electrode, and expose the oxygen electrode to an oxygen or air atmosphere, and under the condition of greater than or equal to 500 degrees Celsius, an electrochemical reaction occurs, water vapor or carbon dioxide is electrolyzed to include hydrogen, carbon monoxide or oxygen, which is the working mode of the electrolysis cell.

[0019] The use of the stack of the present application has the following performance advantages:

[0020] (1) Based on the structural advantages of lightweight and compactness, the specific power of the stack is also improved. In the fuel cell mode, it is manifested as the improvement of power output in unit mass and unit volume; in the electrolysis cell mode, it is manifested as the improvement of gas production rate in unit mass and unit volume. High specific power meets the needs of mobile transportation scenarios.

[0021] (2) Based on avoiding the use of metal connectors, the degradation of the performance of the stack caused by high-temperature oxidation corrosion of the metal connectors will not exist. The long-term working stability of the stack is improved, and the service life is prolonged.

[0022] (3) The overall and same-material sealing structure design is more stable, avoiding the mismatch of dissimilar materials. It helps to improve the long-term working stability of the stack and prolong the service life. BRIEF DESCRIPTION OF DRAWINGS

[0023] The application will be further described below in conjunction with the drawings and examples.

[0024] Figure 1 It is a top view of the overall solid oxide fuel cell / electrolysis cell stack of the application;

[0025] Figure 2 It is a bottom view of the overall solid oxide fuel cell / electrolysis cell stack of the application;

[0026] Figure 3 It is a side perspective view of the overall solid oxide fuel cell / electrolysis cell stack of the application;

[0027] Figure 4 It is a perspective view of the overall solid oxide fuel cell / electrolysis cell unit of the application;

[0028] Figure 5 It is a functional layer structure and working schematic diagram of the overall solid oxide fuel cell / electrolysis cell stack of the application. DETAILED DESCRIPTION

[0029] Various example embodiments and details are described below with reference made to the related drawings. These drawings can not be to scale and elements of similar structures or function can be denoted by like reference numerals throughout the drawings. These drawings are only intended to facilitate description of the embodiments. They are not intended as a complete description of the application nor as an illustration of all of the aspects or advantages of the application. Additionally, the illustrated embodiments are not necessarily all inclusive nor do they necessarily exhibit all aspects or advantages described.

[0030] In the description of the application, it needs to be clear that the terms "internal", "external", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the application, and do not mean that the devices or elements referred to must have a specific orientation or position, and therefore cannot be understood as a limitation on the application.

[0031] As Figures 1 to 5As shown, on the one hand, this embodiment provides an integral solid oxide fuel cell / electrolyzer stack; the stack is integrated by an integral solid oxide fuel cell / electrolyzer unit 20 through a connector structure 13; the integral solid oxide fuel cell / electrolyzer unit includes an internal supporting thin-wall structure 1, an external thin-wall sealing structure 4, an external supporting structure 12, a fuel electrode coating 2, an oxygen electrode coating 3 and a current collecting coating structure 5; the internal supporting thin-wall structure 1, the external thin-wall sealing structure 4, the external supporting structure 12 and the connector 13 are a structure connected in an integral manner and are an integral component. The shape of the internal supporting thin-walled structure 1 is a three-periodic minimal surface with a thickness; the internal supporting thin-walled structure 1 and the external thin-walled sealing structure 4 form at least one cavity 6; the cavity is an air flow channel for fuel gas or oxygen-rich gas, and has at least one air inlet 10 and at least one exhaust port 14; the fuel electrode coating 2 and the oxygen electrode coating 3 are respectively covered on both side surfaces of the internal supporting thin-walled structure 1; the current collecting coating structure 5 is covered on the surface of the fuel electrode coating 2 and the oxygen electrode coating 3, and can eventually form a circuit connected with an external electrical appliance or power supply; the external supporting structure 12 is connected to the connector 13; the external supporting structure 12 has at least one exhaust hole 11 for discharging gas on one side of the oxygen electrode.

[0032] The model design of the integral structure including the internal supporting thin-wall structure 1, the external thin-wall sealing structure 4, the external supporting structure 12 and the connector 13 is completed by three-dimensional structural design software.

[0033] In a specific embodiment: the integral structure is formed by additive manufacturing technology including but not limited to photo-curing additive manufacturing technology; the formed integral structure is subjected to cleaning, degreasing and sintering processes to achieve a dense structure with a relative density of not less than 98%.

[0034] In a specific embodiment: the materials of the monolithic structure include various materials that are currently widely used and verified and materials that will be developed in the future, such as typical ion conductor materials including but not limited to yttria-stabilized zirconia; such as typical proton conductor materials including but not limited to barium ceria-based and barium zirconate-based ceramic materials.

[0035] In a specific embodiment, the thickness of the internal supporting thin-wall structure is less than or equal to 500 microns.

[0036] In specific embodiments: the fuel electrode coating and the oxygen electrode coating are applied to the two side surfaces of the internal support thin-walled structure after the integral structure is manufactured, by using methods including but not limited to infiltration coating methods; the fuel electrode material and the oxygen electrode material are formulated into slurry or ink-like precursors; taking the manufacture of the fuel electrode as an example, the liquid flow precursor of the fuel electrode is poured from the gas flow channel port 10 or 14 until it is full, and after standing for greater than or equal to 1 second, gas flow is applied at one of the gas flow channel ports 10 or 14, such as using an air gun, to remove the residual liquid flow precursor that is not attached to the surface of the internal support thin-walled structure from the other channel port; after drying, debinding and sintering, the electrode coating is firmly combined with the internal support thin-walled structure, and the thickness of the electrode can be increased by repeating the above steps, and the final working fuel electrode has a thickness of greater than or equal to 2 μm; the manufacturing principle of the oxygen electrode is consistent with that of the fuel electrode, the liquid flow precursor of the electrode is covered on the surface of the internal support thin-walled structure opposite to the fuel electrode by methods such as spraying, infiltration or immersion, residual liquid flow precursor is removed by applying gas flow, and the electrode coating is firmly combined with the internal support thin-walled structure after drying, debinding and sintering, and the thickness of the oxygen electrode can be increased by repeating the above steps, and the final working fuel electrode and oxygen electrode have a thickness of greater than or equal to 2 μm.

[0037] In specific embodiments: the material of the fuel electrode includes various materials that have been widely used and verified at present and materials to be developed in the future, such as typical fuel electrode materials including but not limited to yttria-stabilized zirconia mixed with nickel oxide, i.e. Ni-YSZ electrode, and cerium-barium-zirconium-yttrium oxide mixed with nickel oxide, i.e. Ni-BCZY electrode.

[0038] In specific embodiments: the material of the oxygen electrode includes various materials that have been widely used and verified at present and materials to be developed in the future, such as typical oxygen electrode materials including but not limited to yttria-stabilized zirconia mixed with lanthanum-strontium-manganese oxide mixed with yttria-stabilized zirconia, i.e. LSM-YSZ electrode, and barium-strontium-cobalt-iron oxide, i.e. BSCF electrode.

[0039] In specific embodiments: the material of the current collecting coating includes various materials that have been widely used and verified at present and materials to be developed in the future, such as typical electronic conductor materials including but not limited to platinum, gold, silver, nickel, etc.

[0040] In specific embodiments: the current collecting coating is made in the same way as the fuel electrode coating and the oxygen electrode coating, the liquid flow precursor of the current collecting coating is applied to the surface of the corresponding electrode coating, and the current collecting coating is firmly combined with the corresponding electrode coating after drying, debinding and sintering.

[0041] In specific embodiments: the thickness of the current collecting coating is greater than or equal to 2 μm.

[0042] The other aspect of the embodiment provides a method for using the integrated solid oxide fuel cell / electrolysis cell stack, comprising the following steps:

[0043] (1) Fuel cell mode: connect the external electrical load to the current collector structure 5 covering the surface of the fuel electrode 2 and the oxygen electrode 3, and pass the fuel gas including but not limited to hydrogen into the fuel electrode gas flow channel through the gas inlet 10, expose the oxygen electrode 3 to the oxygen-rich gas such as oxygen or air, and under the condition of greater than or equal to 500 degrees Celsius, the electrochemical reaction occurs, the chemical energy is converted into electrical energy, and the external electrical load is powered; the tail gas such as water vapor generated by the fuel electrode is discharged from the exhaust port 14 of the fuel electrode gas flow channel and collected by the external device; the tail gas of the oxygen electrode is discharged through the exhaust port 11 on the external support structure.

[0044] (2) Electrolysis cell mode: connect the external power supply to the current collector structure 5 covering the surface of the fuel electrode 2 and the oxygen electrode 3, and pass the water vapor into the gas flow channel of the fuel electrode 2 through the gas inlet 10, expose the oxygen electrode 3 to the oxygen-rich gas such as oxygen or air, and under the condition of greater than or equal to 500 degrees Celsius, the electrochemical reaction occurs, and the water vapor is electrolyzed to produce hydrogen and oxygen; the hydrogen generated by the fuel electrode is discharged from the exhaust port 14 of the fuel electrode gas flow channel and collected by the external device; the oxygen of the oxygen electrode layer is discharged through the exhaust port 11 on the external support structure.

[0045] In specific embodiments: the fuel gas used in the integrated solid oxide fuel cell stack includes but is not limited to hydrogen, methane, carbon monoxide, ammonia, ethanol, synthetic gas, etc.

[0046] In specific embodiments: the fuel gas used in the integrated solid oxide electrolysis cell stack includes but is not limited to water vapor, carbon dioxide, etc.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them. Although the present application has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present application can be modified or replaced by equivalents, as long as they do not deviate from the purpose and scope of the technical solutions of the present application. These modifications and replacements should be covered in the scope of the claims of the present application.

Claims

1. An integrated solid oxide fuel cell / electrolyzer stack, characterized by: The monolithic solid oxide fuel cell / electrolyzer stack comprises at least one monolithic solid oxide fuel cell / electrolyzer unit, wherein each solid oxide fuel cell / electrolyzer unit is integrated by at least one connector structure; the solid oxide fuel cell / electrolyzer unit comprises an internal supporting thin-wall structure, an external thin-wall sealing structure, an external supporting structure, a fuel electrode coating, an oxygen electrode coating, and a current collecting coating structure; the internal supporting thin-wall structure is in the shape of a three-periodic minimal surface having a thickness; the internal supporting thin-wall structure and the external thin-wall sealing structure form at least one cavity having at least two openings; the fuel electrode coating covers the surface of the cavity, and the oxygen electrode coating covers the opposite side of the fuel electrode coating, and is isolated by the internal supporting thin-wall structure; The current collecting coating structure covers the surface of the fuel electrode coating and the oxygen electrode coating and is connected to an external electrical appliance or power source; the external supporting structure is connected to the connector structure.

2. The monolithic solid oxide fuel cell / electrolyzer stack according to claim 1, wherein: The battery's internal supporting thin-wall structure, external thin-wall sealing structure, external supporting structure and connector structure are an integral structure that can be formed by additive manufacturing technology.

3. The monolithic solid oxide fuel cell / electrolyzer stack according to claim 2, wherein: The thickness of the internal supporting thin-wall structure is less than or equal to 500 microns.

4. The monolithic solid oxide fuel cell / electrolyzer stack according to claim 3, wherein: The inner supporting thin-wall structure is a solid material having ion conductivity or proton conductivity.

5. The integrated solid oxide fuel cell / electrolyzer stack according to claim 4, characterized in that: The relative density of the internal supporting thin-wall structure and the external thin-wall sealing structure is greater than or equal to 98%.

6. The monolithic solid oxide fuel cell / electrolyzer stack according to claim 1, wherein: The fuel electrode coating and the oxygen electrode coating are respectively coated on the two side surfaces of the internal supporting thin-wall structure using liquid fluid or gas fluid as precursors.

7. The integrated solid oxide fuel cell / electrolyzer stack according to claim 6, characterized in that: The final thickness of the fuel electrode coating and the oxygen electrode coating after co-sintering is greater than or equal to 2 microns.

8. The integrated solid oxide fuel cell / electrolyzer stack according to claim 7, characterized in that: The fuel electrode coating and the oxygen electrode coating have a porous structure after being co-sintered, and the porosity is greater than or equal to 30%.

9. The monolithic solid oxide fuel cell / electrolyzer stack according to claim 1, wherein: The outer support structure has at least one exhaust port.

10. A method for operating an integrated solid oxide fuel cell / electrolyzer stack, characterized in that: The method comprises the following steps: introducing a fuel gas containing carbon, hydrogen, or oxygen into a cavity covered by a fuel electrode coating, introducing an oxygen-rich gas into a cavity covered by an oxygen electrode coating, or exposing a surface covered by the oxygen electrode coating to an oxygen-rich atmosphere; under conditions of a temperature greater than or equal to 500 degrees Celsius, an electrochemical reaction occurs, and chemical energy is converted into electrical energy to supply power to external electrical appliances; connecting an external power source to the fuel electrode and the oxygen electrode, and applying power, introducing a gas containing water or carbon dioxide into the cavity covered by the fuel electrode coating, introducing an oxygen-rich gas into the cavity covered by the oxygen electrode coating, or exposing a surface covered by the oxygen electrode coating to an oxygen-rich atmosphere; under conditions of a temperature greater than or equal to 500 degrees Celsius, an electrochemical reaction occurs, and the electrical energy is used to produce a gas containing carbon, hydrogen, or oxygen.

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