High-entropy cathode material, solid oxide fuel cell and preparation method

Abstract

The invention provides a high-entropy cathode material, a solid oxide fuel cell and a preparation method, and relates to the technical field of fuel cells. The preparation method comprises the following steps: dissolving praseodymium nitrate, barium acetate, strontium nitrate, lanthanum nitrate, calcium acetate, neodymium nitrate and cobalt nitrate in deionized water to obtain a first solution; adding citrate and a chelating agent into the first solution to obtain a second solution; adjusting the pH value of the second solution to 7-10 by using ammonia water to obtain a third solution; heating and stirring the third solution to obtain a gelatinous mixture; and drying, grinding and sintering the gelatinous mixture to obtain the high-entropy cathode material for the solid oxide fuel cell. According to the invention, the electrochemical performance of the cathode material for the solid oxide fuel cell can be improved.

Description

Technical Field

[0001] This disclosure relates to the field of fuel cell technology, and more specifically, to a high-entropy cathode material, a solid oxide fuel cell, and a method for its preparation. Background Technology

[0002] In recent years, environmental pollution and the energy crisis have received widespread attention. In order to at least alleviate these problems, solid oxide fuel cells (SOFCs), which have the characteristics of high energy conversion efficiency, low emissions, and fuel renewability, have emerged.

[0003] A typical SOFC is characterized by a sandwich structure consisting of a porous anode, a dense electrolyte, and a porous cathode. To achieve excellent electrochemical performance, the cathode material needs to exhibit high conductivity and significant oxygen reduction reaction activity.

[0004] Currently, cathode materials in this field suffer from poor performance.

[0005] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0006] The purpose of this disclosure is to provide a high-entropy cathode material, a solid oxide fuel cell, and a method for its preparation, thereby overcoming, to at least some extent, the problem of poor performance of cathode materials for solid oxide fuel cells.

[0007] According to a first aspect of this disclosure, a method for preparing a high-entropy cathode material for a solid oxide fuel cell is provided, comprising: dissolving praseodymium nitrate, barium acetate, strontium nitrate, lanthanum nitrate, calcium acetate, neodymium nitrate, and cobalt nitrate in deionized water to obtain a first solution; adding citrate and a chelating agent to the first solution to obtain a second solution; adjusting the pH of the second solution to 7-10 using ammonia to obtain a third solution; heating and stirring the third solution to obtain a gel-like mixture; and drying, grinding, and sintering the gel-like mixture to obtain the high-entropy cathode material for a solid oxide fuel cell.

[0008] Optionally, the temperature for drying the gel-like mixture is 100~200℃, and the drying time is 10~20h.

[0009] Optionally, the grinding time is 1 to 2 hours.

[0010] Optionally, the sintering process includes a first sintering process and a second sintering process performed sequentially; in the first sintering process, the sintering temperature is 400~600℃ and the sintering time is 4~6h; in the second sintering process, the sintering temperature is 1000~1200℃ and the sintering time is 2~4h.

[0011] According to a second aspect of this disclosure, a high-entropy cathode material for solid oxide fuel cells is provided, which is prepared using any of the above-described methods for preparing a high-entropy cathode material for solid oxide fuel cells.

[0012] According to a third aspect of this disclosure, a method for preparing a solid oxide fuel cell is provided, comprising: mixing GDC powder, pine resin alcohol solvent, and a high-entropy cathode material to obtain a target slurry; wherein the high-entropy cathode material is prepared using any of the above-described methods for preparing high-entropy cathode materials for solid oxide fuel cells; performing multiple screen printing operations on an anode electrolyte layer using the target slurry to obtain an intermediate cell; and sintering the intermediate cell to obtain a solid oxide fuel cell.

[0013] Optionally, GDC powder, pine resin alcohol solvent, and high-entropy cathode material are mixed to obtain the target slurry, including: placing GDC powder, 3-8%wt of pine resin alcohol solvent, and high-entropy cathode material in an agate mortar for grinding and mixing to obtain the target slurry; wherein the mass ratio of high-entropy cathode material to GDC powder is 1:0.5 to 1:0.8, and the solid-liquid mass ratio of the target slurry is 1:0.8 to 1:1.5.

[0014] Optionally, the number of screen printing operations is 5 to 8 times. The process of a single screen printing operation includes: screen printing once on a 200 to 420 mesh screen using a screen printing machine, and drying at 100 to 250°C; wherein the target paste is placed in the screen printing machine.

[0015] Optionally, the intermediate cell is sintered to obtain a solid oxide fuel cell, including: placing the intermediate cell in a muffle furnace and sintering it at 1000~1200°C for 2~5 hours in an air atmosphere to obtain a solid oxide fuel cell.

[0016] According to a fourth aspect of this disclosure, a solid oxide fuel cell is provided, which is prepared using any of the above-described methods for preparing a solid oxide fuel cell.

[0017] In the exemplary embodiments of this disclosure, on the one hand, using high-entropy materials as cathode materials for solid oxide fuel cells can significantly improve the conductivity of the cathode material, thereby enhancing the electrochemical performance of the solid oxide fuel cell. On the other hand, the solutions of this disclosure can precisely control the microstructure and properties of the material by controlling the details of the preparation process.

[0018] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this disclosure. Attached Figure Description

[0019] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure. It is obvious that the drawings described below are merely some embodiments of this disclosure, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0020] Figure 1 A flowchart illustrating a method for preparing a high-entropy cathode material for a solid oxide fuel cell according to an embodiment of the present disclosure is shown.

[0021] Figure 2 A flowchart illustrating a method for preparing a solid oxide fuel cell according to an embodiment of the present disclosure is shown.

[0022] Figure 3 A schematic diagram of a scanning electron microscope (SEM) image of a high-entropy cathode material according to an embodiment of this disclosure is shown. In the diagram, a represents the morphology at a scale of 10 μm; b represents the morphology at a scale of 1 μm for the corresponding region.

[0023] Figure 4 A schematic diagram illustrating the microscopic distribution of elements in the high-entropy cathode material according to an embodiment of this disclosure is shown. Wherein, a represents the microscopic distribution of praseodymium; b represents the microscopic distribution of barium; c represents the microscopic distribution of strontium; d represents the microscopic distribution of lanthanum; e represents the microscopic distribution of calcium; f represents the microscopic distribution of neodymium; g represents the microscopic distribution of cobalt; and h represents the microscopic distribution of oxygen.

[0024] Figure 5 A schematic diagram of X-ray diffraction (XRD) of a high-entropy cathode material according to an embodiment of the present disclosure is shown.

[0025] Figure 6 A schematic diagram of a sample according to an embodiment of the present disclosure is shown. In this diagram, a is a schematic diagram of the target slurry; b is a schematic diagram of a button battery prepared using the method of the present disclosure.

[0026] Figure 7 A schematic diagram showing the impedance performance test results of the battery prepared according to the embodiments of this disclosure at different temperatures is illustrated.

[0027] Figure 8 A schematic diagram showing the electrochemical performance test results of the battery prepared according to the embodiments of this disclosure at different temperatures is illustrated. Detailed Implementation

[0028] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided to make this disclosure more comprehensive and complete, and to fully convey the concept of the exemplary embodiments to those skilled in the art. The described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided to give a full understanding of embodiments of this disclosure. However, those skilled in the art will recognize that the technical solutions of this disclosure can be practiced with one or more of these specific details omitted, or other methods, processes, steps, etc., can be employed. In other instances, well-known technical solutions are not shown or described in detail to avoid obscuring various aspects of this disclosure.

[0029] Furthermore, the accompanying drawings are merely illustrative of this disclosure and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and therefore repeated descriptions of them will be omitted. The flowcharts shown in the drawings are merely exemplary illustrations and do not necessarily include all steps. For example, some steps may be broken down, while others may be combined or partially combined; therefore, the actual order of execution may change depending on the actual situation. Additionally, all terms such as "first," "second," and "third" below are for distinguishing purposes only and should not be construed as limiting the content of this disclosure.

[0030] In recent years, high-entropy alloy materials composed of five or more metallic elements have attracted widespread attention due to their unique composition, structure and properties.

[0031] The high-entropy cathode material of this disclosure contains Pr, Ba, Sr, La, Ca, Nd, and Co elements, and can be referred to as PBSLCNC material. Furthermore, since the prepared high-entropy cathode material is a powder, it can also be called PBSLCNC powder.

[0032] Figure 1 A flowchart illustrating a method for preparing a high-entropy cathode material for a solid oxide fuel cell according to an embodiment of the present disclosure is shown schematically. (Reference) Figure 1 The preparation method of this high-entropy cathode material may include the following steps: S10. Dissolve praseodymium nitrate, barium acetate, strontium nitrate, lanthanum nitrate, calcium acetate, neodymium nitrate, and cobalt nitrate in deionized water to obtain the first solution.

[0033] According to some embodiments of this disclosure, the contents of praseodymium nitrate, barium acetate, strontium nitrate, lanthanum nitrate, calcium acetate, neodymium nitrate, and cobalt nitrate can be determined based on the stoichiometric ratios of Pr, Ba, Sr, La, Ca, Nd, and Co elements in the PBSLCNC. For example, when the contents of each of the above elements are the same, the high-entropy cathode material prepared according to the embodiments of this disclosure can be denoted as Pr 1 / 6 Ba 1 / 6 Sr 1 / 6 La 1 / 6 Ca 1 / 6 Nd 1 / 6 CoO3.

[0034] S12. Add citrate and chelating agent to the first solution to obtain the second solution.

[0035] According to some embodiments of this disclosure, when praseodymium nitrate, barium acetate, strontium nitrate, lanthanum nitrate, calcium acetate, neodymium nitrate, and cobalt nitrate in step S10 are all referred to as metal salts, the mass of citrate added in step S12 can be 1 to 2 times the total mass of the aforementioned metal salts.

[0036] The chelating agent used in this embodiment can be, for example, EDTA (Ethylene Diamine Tetraacetic Acid). The mass of the chelating agent added in step S12 can be equal to the total mass of the metal salts mentioned above.

[0037] Specifically, the citrate and chelating agent can be completely dissolved in the first solution by stirring to obtain the second solution.

[0038] S14. Adjust the pH of the second solution to 7-10 using ammonia water to obtain the third solution.

[0039] S16. Heat and stir the third solution to obtain a gel-like mixture.

[0040] S18. The gel-like mixture is dried, ground, and sintered to obtain a high-entropy cathode material for solid oxide fuel cells.

[0041] According to some embodiments of this disclosure, the drying temperature for the gel-like mixture can be 100~200°C, and the drying time is 10~20 hours. Specifically, the gel-like mixture is placed in an oven to dry, forming a dry gel.

[0042] Next, the dry gel can be ground into powder for 1-2 hours.

[0043] The powder is then placed in a muffle furnace for sintering. The sintering process of this embodiment includes a first sintering process and a second sintering process performed sequentially. In the first sintering process, the sintering temperature is 400~600℃, and the sintering time is 4~6 hours. In the second sintering process, the sintering temperature is 1000~1200℃, and the sintering time is 2~4 hours.

[0044] It should be noted that the PBSLCNC powder prepared in steps S10 to S18 of this disclosure is a pure PBSLCNC oxide phase, and this powder material is used as a high-entropy cathode material for solid oxide fuel cells.

[0045] Furthermore, this disclosure also provides a high-entropy cathode material for solid oxide fuel cells, which is prepared using the preparation method for high-entropy cathode materials for solid oxide fuel cells described in steps S10 to S18 above.

[0046] Furthermore, this disclosure also provides a method for preparing a solid oxide fuel cell.

[0047] Figure 2 A flowchart illustrating a method for preparing a solid oxide fuel cell according to an embodiment of the present disclosure is shown schematically. (Reference) Figure 2 The method for preparing this solid oxide fuel cell may include the following steps: S20. GDC powder, pine resin alcohol solvent and high entropy cathode material are mixed to obtain the target slurry.

[0048] In an exemplary embodiment of this disclosure, the GDC powder is Ce. 0.9 Gd 0.1 O 1.95 Powder. The mass fraction of pine resin alcohol solvent can be 3-8% wt. It can be understood that 3-8% wt pine resin alcohol solvent contains pine resin alcohol with a mass fraction of 3-8% wt ethyl cellulose. The high-entropy cathode material is prepared using the preparation method for high-entropy cathode materials for solid oxide fuel cells described in steps S10 to S18 above.

[0049] For the preparation of 3-8%wt terpineol solvent, ethyl cellulose solid powder and terpineol can be ball-milled and mixed. The balls used in the ball mill can be alumina balls with a diameter of, for example, 5-8 mm, a rotation speed of 200-400 r / min, a ball milling time of 12-24 h, and a viscosity of 2-6 kPa·s.

[0050] According to some embodiments of this disclosure, GDC powder, 3-8% wt pine resin alcohol solvent, and high-entropy cathode material can be placed in an agate mortar and ground and mixed for 1-2 hours to obtain the target slurry. The mass ratio of high-entropy cathode material to GDC powder is 1:0.5 to 1:0.8, and the solid-liquid mass ratio of the target slurry is 1:0.8 to 1:1.5.

[0051] S22. Perform multiple screen printing operations on the anode electrolyte layer using the target paste to obtain the intermediate cell.

[0052] According to some embodiments of this disclosure, the number of screen printing operations can be 5 to 8. A single screen printing operation may include: screen printing once on a 200-420 mesh screen using a screen printing machine, for example, using a rubber squeegee, followed by drying at 100-250°C. The target paste is placed inside the screen printing machine. Furthermore, during the screen printing process, the tension is controlled at 25±2N.

[0053] After the above treatment, the cathode thickness can be controlled within 10~30μm.

[0054] S24. The intermediate cell is sintered to obtain a solid oxide fuel cell.

[0055] According to some embodiments of this disclosure, the intermediate cell can be placed in a muffle furnace and sintered in air at 1000-1200°C for 2-5 hours to obtain a solid oxide fuel cell. Furthermore, during the sintering process, organic matter such as terpineol and ethyl cellulose in the screen printing paste can be completely removed, while simultaneously ensuring a dense cathode sinter.

[0056] Furthermore, this disclosure also provides a solid oxide fuel cell, which can be prepared using the solid oxide fuel cell preparation method described in steps S20 to S24 above.

[0057] The following example illustrates the implementation scheme of this disclosure.

[0058] First, dissolve praseodymium nitrate, barium acetate, strontium nitrate, lanthanum nitrate, calcium acetate, neodymium nitrate, and cobalt nitrate in deionized water. Then, add citrate and EDTA in a ratio of 1:1.5:1. In this ratio, the first digit '1' corresponds to the total mass of praseodymium nitrate, barium acetate, strontium nitrate, lanthanum nitrate, calcium acetate, neodymium nitrate, and cobalt nitrate; the second digit '1.5' corresponds to the mass of citrate; and the third digit '1' corresponds to the mass of EDTA. Stir until completely dissolved.

[0059] Next, the pH of the above solution was adjusted to 9 with a certain amount of ammonia water, and then dried in an oven at 120°C for 20 hours to form a dry gel.

[0060] Subsequently, the dry gel was ground into powder and sintered in a muffle furnace at 1200°C for 3 hours to obtain the PBSLCNC powder of the present invention.

[0061] Figure 3 A schematic diagram of a scanning electron microscope (SEM) of a high-entropy cathode material according to an embodiment of this disclosure is shown. In the diagram, a represents the morphology at a scale of 10 μm; b represents the morphology at a scale of 1 μm for the corresponding region. (Reference) Figure 3 The PBSLCNC powder prepared in this embodiment has a particle size between 250 and 530 nm, and the material has high uniformity and small particle size.

[0062] Figure 4 A schematic diagram illustrating the microscopic distribution of elements in the high-entropy cathode material according to an embodiment of this disclosure is shown. Wherein, a represents the microscopic distribution of praseodymium; b represents the microscopic distribution of barium; c represents the microscopic distribution of strontium; d represents the microscopic distribution of lanthanum; e represents the microscopic distribution of calcium; f represents the microscopic distribution of neodymium; g represents the microscopic distribution of cobalt; and h represents the microscopic distribution of oxygen.

[0063] refer to Figure 4 As can be seen, all elements in the PBSLCNC powder prepared in this embodiment of the present disclosure exhibit a well-uniform elemental distribution.

[0064] Figure 5 A schematic diagram of X-ray diffraction of a high-entropy cathode material according to an embodiment of this disclosure is shown. (Reference) Figure 5 By combining the PDF cards, it can be seen that the material exhibits a pure perovskite phase, indicating that all elements have successfully entered the perovskite lattice. It is understood that the PDF mentioned here refers to a Powder Diffraction File, which is generally considered a standard answer library for XRD phase analysis. In other words, by comparing experimental data with the standard diffraction peaks in the PDF cards, the crystal structure of the experimental sample can be determined.

[0065] After obtaining PBSLCNC powder, it can be used to prepare solid oxide fuel cells.

[0066] First, weigh 8g of ethyl cellulose solid powder and 92g of terpineol and mix them by ball milling. The ball milling process uses alumina balls with a main diameter of 5mm, a rotation speed of 250r / min, and a milling time of 18h. This will produce terpineol containing 8% ethyl cellulose with a viscosity of 3kPa·s.

[0067] Next, 5g of the above-mentioned PBSLCNC powder, 1g of GDC powder, and 5g of pine resin alcohol binder containing 8% ethyl cellulose were mixed and ground for 1.5 hours to obtain a target slurry with suitable viscosity. The actual sample of this target slurry is shown below. Figure 6 As shown in Figure a.

[0068] Subsequently, the target slurry is placed into a screen printing machine and screen-printed once on a 200-mesh screen using a rubber squeegee. It is then dried at 150°C. This process constitutes one screen printing operation, which is repeated seven times to obtain a full cell with a certain cathode thickness.

[0069] The full cell is then placed in a muffle furnace and sintered at 1000°C for 3 hours in an air atmosphere to obtain a fully sintered PBSLCNC cathode full cell, which is the solid oxide fuel cell described in this disclosure. Figure 6 Figure b is a schematic diagram of a button battery prepared using the method disclosed herein.

[0070] This disclosure also includes impedance performance tests and electrochemical performance tests on the batteries prepared using the methods described in the embodiments. The test results are as follows: Figure 7 and Figure 8 As shown. Reference Figure 7 and Figure 8 The battery prepared based on the high-entropy cathode material in this embodiment has good battery output performance.

[0071] It should be noted that although the steps of the method in this disclosure are described in a specific order in the accompanying drawings, this does not require or imply that the steps must be performed in that specific order, or that all the steps shown must be performed to achieve the desired result. Additional or alternative steps may be omitted, multiple steps may be combined into one step, and / or a step may be broken down into multiple steps.

[0072] Furthermore, the above figures are merely illustrative of the processes included in the method according to exemplary embodiments of this disclosure and are not intended to be limiting. It is readily understood that the processes shown in the above figures do not indicate or limit the temporal order of these processes. Additionally, it is readily understood that these processes may be executed synchronously or asynchronously, for example, in multiple modules.

[0073] Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the specification and practice of the disclosure herein. This application is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this disclosure are indicated by the claims.

[0074] It should be understood that this disclosure is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this disclosure is limited only by the appended claims.

Claims

1. A method for preparing a high-entropy cathode material for solid oxide fuel cells, characterized in that, include: Praseodymium nitrate, barium acetate, strontium nitrate, lanthanum nitrate, calcium acetate, neodymium nitrate, and cobalt nitrate were dissolved in deionized water to obtain the first solution; Citrate and a chelating agent are added to the first solution to obtain a second solution; The pH of the second solution was adjusted to 7-10 using ammonia water to obtain the third solution; The third solution is heated and stirred to obtain a gel-like mixture; The gel-like mixture is dried, ground, and sintered to obtain a high-entropy cathode material for solid oxide fuel cells.

2. The preparation method according to claim 1, characterized in that, The temperature for drying the gel-like mixture is 100~200℃, and the drying time is 10~20h.

3. The preparation method according to claim 1, characterized in that, The grinding time is 1 to 2 hours.

4. The preparation method according to claim 1, characterized in that, The sintering process includes a first sintering process and a second sintering process performed sequentially. In the first sintering process, the sintering temperature is 400~600℃ and the sintering time is 4~6h; In the second sintering process, the sintering temperature is 1000~1200℃ and the sintering time is 2~4h.

5. A high-entropy cathode material for solid oxide fuel cells, characterized in that, The high-entropy cathode material for solid oxide fuel cells was prepared using any one of claims 1 to 4.

6. A method for preparing a solid oxide fuel cell, characterized in that, include: GDC powder, pine oil alcohol solvent, and high-entropy cathode material are mixed to obtain the target slurry; wherein the high-entropy cathode material is prepared by the preparation method of high-entropy cathode material for solid oxide fuel cells according to any one of claims 1 to 4; Multiple screen printing operations are performed on the anode electrolyte layer using the target slurry to obtain an intermediate battery; The intermediate cell is sintered to obtain a solid oxide fuel cell.

7. The preparation method according to claim 6, characterized in that, GDC powder, pine resin alcohol solvent, and high-entropy cathode material are mixed to obtain the target slurry, comprising: GDC powder, 3-8% wt pine resin alcohol solvent, and high entropy cathode material are placed in an agate mortar and ground and mixed to obtain the target slurry. The mass ratio of the high-entropy cathode material to the GDC powder is 1:0.5 to 1:0.8, and the solid-liquid mass ratio of the target slurry is 1:0.8 to 1:1.

5.

8. The preparation method according to claim 6, characterized in that, The number of screen printing operations is 5 to 8. The process of a single screen printing operation includes: The screen is printed once on a 200-420 mesh screen using a screen printing machine, and then dried at 100-250℃. The target paste is placed inside the screen printing machine.

9. The preparation method according to claim 6, characterized in that, The intermediate cell is sintered to obtain a solid oxide fuel cell, comprising: The intermediate battery is placed in a muffle furnace and sintered at 1000~1200℃ for 2~5 hours in an air atmosphere to obtain a solid oxide fuel cell.

10. A solid oxide fuel cell, characterized in that, The solid oxide fuel cell was prepared using the method described in any one of claims 6 to 9.

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