A high-entropy perovskite cathode material and its preparation method and application

Abstract

The present invention discloses a high entropy perovskite cathode material and its preparation method and application, which belongs to the technical field of solid oxide fuel cell cathode materials. The chemical formula of the high entropy perovskite cathode material is ABO 3‑δ , wherein the A position is Pr, La, Sm, Sr, and Ba; the B position is Co; the molar ratio of Pr, La, Sm, Sr, Ba, and Co is (0.1-0.4):(0.1-0.4):(0.1-0.4):(0.1-0.4):(0.1-0.4):1; 0≤δ<3. The present invention adopts the above-mentioned high-entropy perovskite cathode material and its preparation method and application. The cathode material exhibits a pure phase of perovskite structure, not only has good chemical stability, high redox activity, and low polarization resistance, but also has good compatibility with electrolytes, showing good application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of solid oxide fuel cell cathode materials, and in particular to a high-entropy perovskite cathode material and a preparation method and application thereof. Background Art

[0002] Solid oxide fuel cells (SOFCs) are energy conversion devices that convert chemical energy directly into electrical energy. Because they operate without the constraints of the Carnot cycle, their energy conversion efficiency reaches as high as 80% and they produce no harmful products. Therefore, they have become a highly sought-after energy storage and conversion device. The cathode is a crucial component of SOFCs, providing a reaction site for the electrochemical reduction of the oxidant.

[0003] Perovskite materials (ABO 3-δ ) has become a highly sought-after mixed ionic and electronic conductor material for solid oxide fuel cell cathodes due to its high electrical conductivity, excellent oxygen reduction reaction activity, high oxygen surface exchange coefficient, and bulk diffusion coefficient. Despite its promising performance, perovskite materials have a high thermal expansion coefficient and poor thermal compatibility with other battery components. This can lead to cracking in batteries over long periods of operation, and in severe cases, cathode detachment. Furthermore, under high-temperature operating conditions, perovskite materials are susceptible to poisoning by chromium-containing gases emitted from chromium-containing stainless steel interconnects and by carbon dioxide gas, the working product, leading to deactivation of active sites and a sharp increase in interfacial impedance, limiting their application. To further improve cathode performance, research has been conducted on high-entropy ceramic cathode materials. Currently, research on high-entropy perovskite cathodes (Chinese patents: CN113737214B, CN115050978A) has made considerable progress.

[0004] High-entropy ceramics are multi-component solid solutions formed from five or more different cations, with a mixing entropy greater than or equal to 1.5R. High-entropy ceramics exhibit significant thermodynamic advantages, with minimal Gibbs free energy. Therefore, they maintain good thermodynamic stability even at high temperatures. Summary of the Invention

[0005] The purpose of the present invention is to provide a high-entropy perovskite cathode material, a preparation method and application thereof. The cathode material exhibits a pure phase of perovskite structure, not only has good chemical stability, high redox activity, and low polarization resistance, but also has good compatibility with electrolytes, showing good application prospects.

[0006] To achieve the above object, the present invention provides a high entropy perovskite cathode material, the chemical formula of the high entropy perovskite cathode material is ABO 3-δ, where the A position is Pr, La, Sm, Sr and Ba; the B position is Co; the molar ratio of Pr, La, Sm, Sr, Ba and Co is (0.1-0.4):(0.1-0.4):(0.1-0.4):(0.1-0.4):(0.1-0.4):1; 0≤δ<3.

[0007] The present invention also provides a method for preparing a high entropy perovskite cathode material, comprising the following steps:

[0008] S1. Weigh praseodymium salt, lanthanum salt, samarium salt, strontium salt, barium salt, and cobalt salt in proportion and dissolve them in distilled water to obtain a precursor solution;

[0009] S2. Adding a dispersant, a monomer, a crosslinking agent, and an initiator to the precursor solution obtained in S1, stirring and heating until a dry gel is formed;

[0010] S3, calcining the dry gel obtained in S2 to obtain a precursor powder;

[0011] S4. calcining the precursor powder obtained in S3 to obtain a high entropy perovskite cathode material.

[0012] Preferably, in S1, the praseodymium salt, lanthanum salt, samarium salt, strontium salt, barium salt, and cobalt salt are all nitrates or hydrated nitrates.

[0013] Preferably, in S2, the mass ratio of the total metal salt to the dispersant, monomer, crosslinking agent, and initiator in the precursor solution is 1:0.04:0.6:0.06:0.1;

[0014] The initiator is an APS solution, and the solute of the APS solution is 2 wt % ammonium persulfate.

[0015] Preferably, in S2, the heating temperature is 80-300°C.

[0016] Preferably, in S3, the calcination temperature is 400-500° C., and the calcination time is 1-3 hours.

[0017] Preferably, in S4, the calcination temperature is 900-1200° C., the heating rate is 1-10° C. / min, and the calcination time is 2-15 h.

[0018] The present invention also provides an application of a high-entropy perovskite cathode material, wherein the high-entropy perovskite cathode material described above is applied to prepare a solid oxide fuel cell, which includes a symmetrical solid oxide fuel cell and an anode-supported single cell.

[0019] Preferably, the high entropy perovskite cathode material is prepared into a cathode slurry, screen-printed on both sides of the SDC electrolyte, and then heated to 1000-1300°C at a heating rate of 1-10°C / min and calcined for 2-10h to obtain a symmetrical solid oxide fuel cell.

[0020] Preferably, the high entropy perovskite cathode material is prepared into a cathode slurry, screen-printed on the electrolyte side of the anode-supported single cell, and then heated to 1000-1300°C at a heating rate of 1-10°C / min and calcined for 2-10h to obtain an anode-supported single cell.

[0021] Therefore, the present invention adopts the above-mentioned high-entropy perovskite cathode material and its preparation method and application. The cathode material exhibits a pure phase of perovskite structure, which not only has good chemical stability, high redox activity, and low polarization resistance, but also has good compatibility with electrolytes, showing good application prospects.

[0022] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The present invention is a high entropy perovskite cathode material and its preparation method and application example 1 prepared Pr 0.2 La 0.2 Sm 0.2 Sr 0.2 Ba 0.2 XRD pattern of CoO3 cathode material;

[0024] Figure 2 The present invention is a high entropy perovskite cathode material and its preparation method and application example 1 prepared Pr 0.2 La 0.2 Sm 0.2 Sr 0.2 Ba 0.2 Microscopic morphology of CoO3 cathode material;

[0025] Figure 3 The present invention is a high entropy perovskite cathode material and its preparation method and application example 1 prepared Pr 0.2 La 0.2 Sm 0.2 Sr 0.2 Ba 0.2 Impedance diagram of CoO3 cathode material;

[0026] Figure 4 The present invention is a high entropy perovskite cathode material and its preparation method and application example 1 prepared Pr 0.2 La 0.2 Sm 0.2 Sr0.2 Ba 0.2 Impedance diagram of CoO3 cathode material in atmospheres with different carbon dioxide concentrations;

[0027] Figure 5 The present invention is a high entropy perovskite cathode material and its preparation method and application example 1 prepared Pr 0.2 La 0.2 Sm 0.2 Sr 0.2 Ba 0.2 XRD pattern of CoO3 cathode material after 24h carbon dioxide treatment at 700℃;

[0028] Figure 6 The present invention is a high entropy perovskite cathode material and its preparation method and application example 1 prepared Pr 0.2 La 0.2 Sm 0.2 Sr 0.2 Ba 0.2 Impedance diagram of CoO3 cathode material before and after 10h Cr treatment;

[0029] Figure 7 The present invention is a high entropy perovskite cathode material and its preparation method and application using the Pr prepared in Example 1 0.2 La 0.2 Sm 0.2 Sr 0.2 Ba 0.2 The open circuit voltage variation diagram of the anode-supported single cell with CoO3 cathode material as the cathode during 100h long-term operation;

[0030] Figure 8 The present invention is a high entropy perovskite cathode material and its preparation method and application using the Pr prepared in Example 1 0.2 La 0.2 Sm 0.2 Sr 0.2 Ba 0.2 Power density diagram of anode-supported single cell with CoO3 cathode material as cathode at different temperatures. DETAILED DESCRIPTION

[0031] The technical solution of the present invention is further described below with reference to the accompanying drawings and embodiments.

[0032] Unless otherwise defined, technical or scientific terms used in the present invention shall have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs.

[0033] Example 1

[0034] A high entropy perovskite cathode material, the preparation method of which comprises the following steps:

[0035] S1, according to Pr 0.2 La 0.2 Sm 0.2 Sr 0.2 Ba 0.2 The stoichiometric ratio of CoO3 was as follows: 1.342 g of praseodymium nitrate, 1.336 g of lanthanum nitrate hexahydrate, 1.372 g of samarium nitrate hexahydrate, 0.653 g of strontium nitrate, 0.807 g of barium nitrate, and 4.490 g of cobalt nitrate hexahydrate were weighed and fully dissolved in distilled water to obtain a precursor solution.

[0036] S2. Add 0.4 g of dispersant tetramethylammonium hydroxide (TMAH), 6 g of monomer acrylamide (AM), and 0.6 g of cross-linker N,N'-methylenebisacrylamide (MBAM) to the precursor solution obtained in S1 in sequence. After fully dissolving, add 1 g of initiator (APS solution) and stir and heat at 300°C until a dry gel is formed, wherein the solute of the APS solution is 2 wt% of ammonium persulfate.

[0037] S3, placing the dry gel obtained in S2 in a tubular heating furnace and heating it to 400°C at a heating rate of 3°C / min, and calcining it for 2 h to obtain a precursor powder;

[0038] S4, the precursor powder obtained in S3 was placed in a tubular heating furnace and heated to 1100 ° C at a heating rate of 3 ° C / min, and calcined for 2 h to obtain a high entropy perovskite cathode material Pr 0.2 La 0.2 Sm 0.2 Sr 0.2 Ba 0.2 CoO3.

[0039] The high entropy perovskite Pr prepared in Example 1 0.2 La 0.2 Sm 0.2 Sr 0.2 Ba 0.2 CoO3 cathode powder was subjected to XRD test, and the results were as follows Figure 1 As shown, its diffraction peaks correspond to the PDF standard card of perovskite, and no impurity peaks are observed. Figure 2 The high entropy perovskite Pr prepared in Example 1 0.2 La 0.2 Sm 0.2 Sr 0.2 Ba 0.2 Microscopic morphology of CoO3 cathode powder, Figure 2 (a) is a high-resolution transmission electron microscope (HR-TEM) image. Figure 2 (b) is the EDS element distribution map. Figure 2 (c) is the STEM image. Figure 2(d) is the corresponding PLSSBC element mapping diagram. Figure 2 In (a), it can be observed that the lattice fringe spacing corresponds to the PDF standard card; Figure 2 From (b) in the figure, we can see that the powder particles are small in size, with a diameter of about 250nm. Figure 2 From (c) in the figure, we can see that the element ratios shown by the energy spectrum of the point scan are consistent with the expectations. Figure 2 As shown in (d), the surface scanning results show that the elements are evenly distributed. Figure 3 As shown in the figure, the polarization resistance (Rp) of the cathode measured by the electrochemical workstation is low. At 700℃, Rp=0.067Ω cm 2 .like Figure 4 As shown, the carbon dioxide concentration in the working environment is controlled, and the polarization impedance value of the cathode in different carbon dioxide concentration atmospheres is measured by an electrochemical workstation. 0.2 La 0.2 Sm 0.2 Sr 0.2 Ba 0.2 The CoO3 cathode showed good stability and no obvious impedance decay. Figure 5 As shown in the XRD test, at a high temperature of 700℃, the high entropy perovskite Pr 0.2 La 0.2 Sm 0.2 Sr 0.2 Ba 0.2 The CoO3 cathode still maintains the perovskite phase structure after 24 hours of carbon dioxide treatment.

[0040] Example 2

[0041] A high entropy perovskite cathode material, the preparation method of which comprises the following steps:

[0042] S1, according to Pr 0.1 La 0.2 Sm 0.3 Sr 0.25 Ba 0.15 The stoichiometric ratio of CoO3 was as follows: 0.671 g of praseodymium nitrate, 1.336 g of lanthanum nitrate hexahydrate, 2.058 g of samarium nitrate hexahydrate, 0.816 g of strontium nitrate, 0.605 g of barium nitrate, and 4.490 g of cobalt nitrate hexahydrate were weighed and fully dissolved in distilled water to obtain a precursor solution.

[0043] S2. Add 0.4 g of dispersant tetramethylammonium hydroxide (TMAH), 6 g of monomer acrylamide (AM), and 0.6 g of cross-linker N'N methylenebisacrylamide (MBAM) to the precursor solution obtained in S1 in sequence. After fully dissolving, add 1 g of initiator (APS solution), and stir and heat at 280°C until a dry gel is formed, wherein the solute of the APS solution is 2 wt% of ammonium persulfate.

[0044] S3, placing the dry gel obtained in S2 in a tubular heating furnace and heating it to 500°C at a heating rate of 5°C / min, and calcining it for 3 h to obtain a precursor powder;

[0045] S4, the precursor powder obtained in S3 was placed in a tubular heating furnace and heated to 1000 ° C at a heating rate of 5 ° C / min, and calcined for 5 h to obtain a high entropy perovskite cathode material Pr 0.1 La 0.2 Sm 0.3 Sr 0.25 Ba 0.15 CoO3.

[0046] Example 3

[0047] A high entropy perovskite cathode material, the preparation method of which comprises the following steps:

[0048] S1, according to Pr 0.4 La 0.1 Sm 0.2 Sr 0.1 Ba 0.2 The stoichiometric ratio of CoO3 was as follows: 2.684 g of praseodymium nitrate, 0.668 g of lanthanum nitrate hexahydrate, 1.372 g of samarium nitrate hexahydrate, 0.327 g of strontium nitrate, 0.807 g of barium nitrate, and 4.490 g of cobalt nitrate hexahydrate were weighed and fully dissolved in distilled water to obtain a precursor solution.

[0049] S2. Add 0.4 g of dispersant tetramethylammonium hydroxide (TMAH), 6 g of monomer acrylamide (AM), and 0.6 g of cross-linker N'N methylenebisacrylamide (MBAM) to the precursor solution obtained in S1 in sequence. After fully dissolving, add 1 g of initiator (APS solution) and heat with stirring at 300°C until a dry gel is formed, wherein the solute of the APS solution is 2 wt% of ammonium persulfate.

[0050] S3, placing the dry gel obtained in S2 in a tubular heating furnace and heating it to 450°C at a heating rate of 5°C / min, and calcining it for 3 h to obtain a precursor powder;

[0051] S4, the precursor powder obtained in S3 was placed in a tubular heating furnace and heated to 1200 ° C at a heating rate of 5 ° C / min, and calcined for 2 h to obtain a high entropy perovskite cathode material Pr 0.4 La0.1 Sm 0.2 Sr 0.1 Ba 0.2 CoO3.

[0052] Application Example 1

[0053] The Pr prepared in Example 1 0.2 La 0.2 Sm 0.2 Sr 0.2 Ba 0.2 CoO3 cathode material is added with ethyl cellulose and terpineol and ground until a uniform cathode slurry is formed. The cathode slurry is evenly coated on the Ce by screen printing. 0.8 Sm 0.2 O 1.9 The electrolyte (SDC electrolyte) on both sides was heated to 1100°C at a heating rate of 10°C / min and calcined for 2h to obtain a symmetrical solid oxide fuel cell.

[0054] To simulate the contamination of the cathode by chromium-containing materials, two pieces of SUS304 stainless steel (~18wt% Cr) were sandwiched between the two sides of a symmetrical solid oxide fuel cell and placed in a tube furnace. They were calcined at the test temperature (700°C) for 10 hours. The impedance values ​​before and after the 10-hour Cr treatment were measured using an electrochemical workstation. The results are shown in Figure 2. Figure 6 As shown, its impedance value is 0.09Ω cm 2 Increased to 0.128Ω cm 2 , showing excellent resistance to Cr poisoning.

[0055] Application Example 2

[0056] SDC, NiO and graphite were uniformly mixed in a mass ratio of 4:6:1, pressed into sheets and calcined at 1000°C for 2 hours to obtain an anode support sheet. SDC electrolyte solution was then spin-coated on the anode support sheet and calcined at 1500°C for 2 hours. 0.2 La 0.2 Sm 0.2 Sr 0.2 Ba 0.2 The CoO3 cathode material was added with ethyl cellulose and terpineol and ground until a uniform cathode slurry was formed. The cathode slurry was evenly coated on the side of the anode support sheet coated with SDC electrolyte solution by screen printing, and then heated to 1100°C at a heating rate of 10°C / min and calcined for 2h to obtain an anode-supported single cell.

[0057] like Figure 7As shown in the figure, the open circuit voltage of the anode-supported single cell was tested by an electrochemical workstation. During the long-term operation of 100 hours, its open circuit voltage was stable at 0.8V, proving the excellent stability of the high-entropy perovskite cathode. Due to the different thermal expansion coefficients of the cathode and the electrolyte, the cathode is easy to fall off, but the high-entropy material can suppress its own thermal expansion to a certain extent, making it more compatible with the electrolyte. The long-term operation test also proves that the high-entropy perovskite cathode has good compatibility with the electrolyte. Figure 8 As shown in the figure, the current-voltage curve of the anode-supported single cell prepared with the high-entropy perovskite cathode was measured by an electrochemical workstation. At an operating temperature of 700°C, the power density of the anode-supported single cell reached 0.9 W cm -2 , proving that the high-entropy perovskite cathode has excellent electrochemical performance.

[0058] Therefore, the present invention adopts the above-mentioned high-entropy perovskite cathode material and its preparation method and application. The cathode material exhibits a pure phase of perovskite structure, which not only has good chemical stability, high redox activity, and low polarization resistance, but also has good compatibility with electrolytes, showing good application prospects.

[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and do not limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solutions of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A high entropy perovskite cathode material, characterized in that The general chemical formula of the high entropy perovskite cathode material is ABO 3-δ , wherein the A position is Pr, La, Sm, Sr and Ba; the B position is Co; the molar ratio of Pr, La, Sm, Sr, Ba and Co is (0.1-0.4):(0.1-0.4):(0.1-0.4):(0.1-0.4):(0.1-0.4):1; 0≤δ<3; The method for preparing the high entropy perovskite cathode material comprises the following steps: S1. Weigh praseodymium salt, lanthanum salt, samarium salt, strontium salt, barium salt, and cobalt salt in proportion and dissolve them in distilled water to obtain a precursor solution; S2. Adding a dispersant, a monomer, a crosslinking agent, and an initiator to the precursor solution obtained in S1, stirring and heating until a dry gel is formed; S3, calcining the dry gel obtained in S2 to obtain a precursor powder; S4. calcining the precursor powder obtained in S3 to obtain the high entropy perovskite cathode material.

2. A high entropy perovskite cathode material according to claim 1, characterized in that: In S1, the praseodymium salt, lanthanum salt, samarium salt, strontium salt, barium salt and cobalt salt are all nitrates or hydrated nitrates.

3. A high entropy perovskite cathode material according to claim 1, characterized in that: In S2, the mass ratio of total metal salt to dispersant, monomer, cross-linker, and initiator in the precursor solution is 1:0.04:0.6:0.06:0.1; The initiator is an APS solution, and the solute of the APS solution is 2 wt % ammonium persulfate.

4. A high entropy perovskite cathode material according to claim 1, characterized in that: In S2, the heating temperature is 80~300℃.

5. The high entropy perovskite cathode material according to claim 1, characterized in that: In S3, the calcination temperature is 400-500°C, and the calcination time is 1-3 hours.

6. A high entropy perovskite cathode material according to claim 1, characterized in that: In S4, the calcination temperature is 900-1200° C., the heating rate is 1-10° C. / min, and the calcination time is 2-15 h.

7. An application of a high entropy perovskite cathode material, characterized in that: The high entropy perovskite cathode material according to any one of claims 1 to 6 is used to prepare a solid oxide fuel cell, which includes a symmetrical solid oxide fuel cell and an anode-supported single cell.

8. The use of a high entropy perovskite cathode material according to claim 7, characterized in that: The high-entropy perovskite cathode material is prepared into a cathode slurry, screen-printed on both sides of the SDC electrolyte, and then heated to 1000-1300°C at a heating rate of 1-10°C / min and calcined for 2-10h to produce a symmetrical solid oxide fuel cell.

9. The use of a high entropy perovskite cathode material according to claim 7, characterized in that: The high-entropy perovskite cathode material is prepared into a cathode slurry, screen-printed on the electrolyte side of the anode-supported single cell, and then heated to 1000-1300°C at a heating rate of 1-10°C / min and calcined for 2-10h to obtain an anode-supported single cell.

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