Solid oxide electrolysis cell ba-based electrode material and preparation method and application thereof

Abstract

The application belongs to the technical field of solid oxide electrolysis cells, and particularly relates to a solid oxide electrolysis cell Ba-based electrode material and a preparation method and application thereof. The electrode material has a cubic phase perovskite structure and a chemical formula of Ln 1‑x Ba x M’ 1‑y M” y O 3‑δ , wherein 0

Description

Technical Field

[0001] This invention belongs to the field of solid oxide electrolytic cell technology, specifically relating to a Ba-based electrode material for solid oxide electrolytic cells, its preparation method, and its application. Background Technology

[0002] Since the Industrial Revolution, due to the extensive use of fossil fuels, the atmospheric CO2 concentration has increased from 280 ppm in 1750 to 415 ppm in 2021. The ever-increasing CO2 emissions are a major cause of the worsening greenhouse effect, and how to effectively utilize CO2 is currently a key focus of scientific attention. Solid oxide electrolysis cells (SOECs) are energy conversion devices that utilize clean energy sources such as solar and wind power to convert CO2 into fuels or chemical feedstocks such as CO. They have advantages such as high energy conversion efficiency and being environmentally friendly, attracting widespread attention. SOECs consist of three parts: an electrolyte, an anode, and a cathode. At the cathode, a CO2 reduction reaction occurs, and the generated oxygen ions are conducted through the electrolyte to the anode, where an oxygen evolution reaction occurs, producing O2. The overall performance of SOECs is directly affected by the electrode materials. Good electrode materials need to possess both high ionic and electronic conductivity, as well as catalytic activity for both CO2 reduction and oxygen evolution reactions.

[0003] Composite materials consisting of an ABO3-structured perovskite phase and a cerium oxide-doped fluorite phase are common electrode materials. Typically, the perovskite phase provides electronic conductivity, while the fluorite phase provides oxygen ion conductivity. The A-site in perovskite materials is usually a lanthanide element or an alkaline earth metal. When the alkaline earth metal Ba is used as the A-site element, the material exhibits high ionic conductivity due to its large ionic radius. However, also due to its large ionic radius, Ba is more prone to surface segregation, leading to surface inhomogeneity or the formation of impurity phases, thus affecting its electrochemical performance, especially in CO2-containing reaction atmospheres. Therefore, Ba-based materials are difficult to use as cathode materials in CO2 electrolysis reactions. Summary of the Invention

[0004] This invention provides a Ba-based electrode material for solid oxide electrolyzers, its preparation method, and its application. This electrode material is an electron-ion mixed conductor with good electrical conductivity. Furthermore, due to the presence of lanthanide elements at the A-site and high-valence elements at the B-site, it can suppress Ba segregation, exhibits good resistance to CO2 poisoning, and possesses catalytic activity for both oxygen evolution reaction and carbon dioxide reduction reaction. It can be used as both an anode and cathode electrode material for SOEC.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows:

[0006] On the one hand, the present invention provides a Ba-based electrode material for a solid oxide electrolyzer. The electrode material has a cubic perovskite structure and a chemical formula of Ln 1-x Ba x M’ 1-y M” y O 3-δ , where 0 < x < 1, 0 < y < 0.5, δ is the oxygen vacancy content, Ln is one or more of Pr, Ce, Yb, M’ is one or more of Fe, Co, Ni, Cu, Zn, Mn, Cr, and M” is one or more of V, Ti, Zr, Nb, Mo.

[0007] In the above technical solution, further, Ln is Pr, M’ is Co and Fe, and M” is Ti.

[0008] On the other hand, the present invention provides a preparation method for the above electrode material. The method includes the following steps:

[0009] (1) Dissolve the required metal precursors in water according to the stoichiometric ratio of Ln 1-x Ba x M’ 1-y M” y O 3-δ to obtain a metal salt aqueous solution;

[0010] (2) Add a complexing agent to the metal salt aqueous solution obtained in step (1) to obtain a complexing sol;

[0011] (3) Heat and stir the complexing sol obtained in step (2) at 60 - 80 °C to evaporate and form a gel, and then self-propagating combustion occurs to obtain primary powder;

[0012] (4) Transfer the primary powder obtained in step (3) to a high-temperature furnace and calcine it at 900 - 1100 °C for 2 - 5 hours to obtain the electrode material powder.

[0013] In the above technical solution, further, the Ln, Ba, and M’ precursors in step (1) are nitrates, the vanadium precursor is ammonium metavanadate, the titanium precursor is isopropyl titanate, the zirconium precursor is zirconium oxynitrate, the niobium precursor is niobium oxalate, and the molybdenum precursor is ammonium molybdate.

[0014] In the above technical solution, further, the complexing agent in step (2) is one or more of citric acid, ammonium citrate, ethylenediaminetetraacetic acid, glycine, polyvinyl alcohol, and polyvinylpyrrolidone, and the molar ratio of the complexing agent to the total molar number of metal ions is 1:1 - 3:1.

[0015] In the above technical solution, further, the heating temperature in step (3) is 80 °C.

[0016] In the above technical solution, the calcination temperature in step (4) is 1100℃ and the calcination time is 3 hours.

[0017] In another aspect, the present invention provides a solid oxide electrolytic cell, the electrolytic cell comprising a cathode, an anode, and an electrolyte; the anode and / or cathode comprising the electrode materials described above.

[0018] In the above technical solution, the method for preparing the electrolytic cell further includes the following steps:

[0019] a. Electrolyte powder is shaped by dry pressing or casting, and then sintered at 1300-1500℃ for 5-10 hours to obtain sheet electrolyte;

[0020] b. Grind and mix the above-mentioned electrode material powder and ion-conducting phase powder in a mortar, add ethyl cellulose-terpineol mixture, and stir evenly to obtain electrode slurry;

[0021] c. Apply electrode paste evenly to the electrolyte surface using screen printing, brushing, or spin coating methods, and calcine at 1000-1200℃ for 2-5 hours. Apply electrode paste of the other electrode to the electrolyte surface in the same way to obtain a solid oxide electrolytic cell.

[0022] In the above technical solution, further, in step a, the electrolyte is yttrium oxide-stabilized zirconium oxide or lanthanum gallate-doped zirconium oxide.

[0023] In the above technical solution, further, in step b, the mass ratio of electrode material powder to ion-conducting phase powder is 70:30-30:70; the ion-conducting phase is Gd. 0.2 Ce 0.8 O 2-δ or Sm 0.2 Ce 0.8 O 2-δ The ethyl cellulose-terpineol mixture contains 4-7 wt.% ethyl cellulose by mass.

[0024] The beneficial effects of this invention are as follows:

[0025] This invention utilizes the doping of lanthanide elements and high-valence elements to improve the chemical stability and CO2 poisoning resistance of Ba-based materials, while also exhibiting good electrical conductivity and catalytic activity in the oxygen evolution reaction and carbon dioxide reduction reaction. It can be used not only as an anode electrode material for SOEC, but also as a cathode electrode material. Attached Figure Description

[0026] Figure 1 For Pr 0.5 Ba 0.5 Co 0.7 Fe 0.2Ti 0.1 O 3-δ (PBCFT72), Pr 0.5 Ba 0.5 Co 0.5 Fe 0.4 Ti 0.1 O 3-δ (PBCFT54) and Pr 0.5 Ba 0.5 Co 0.2 Fe 0.7 Ti 0.1 O 3-δ XRD pattern of (PBCFT27);

[0027] Figure 2 The results show the test results of the electrode materials' resistance to CO2 poisoning. In the figure, a represents the XRD patterns of PBCFT72, PBCFT54, and PBCFT27 after CO2 treatment, and b represents the Ba values ​​before and after CO2 treatment. 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3- XRD pattern of δ(BSCF);

[0028] Figure 3 The surface morphology of the PBCFT72-GDC electrode;

[0029] Figure 4 The CO2 reduction performance of PBCFT72-GDC as a cathode material is given, where a is the electrolysis current density, b is the chronocurrent and Faraday efficiency, and c is the electrochemical impedance spectroscopy.

[0030] Figure 5 The oxygen evolution reaction performance of PBCFT72-GDC as an anode material is given, where a is the electrolysis current density, b is the chronocurrent and Faraday efficiency, and c is the electrochemical impedance spectroscopy. Detailed Implementation

[0031] The present invention will now be described in detail through embodiments, but the scope of the claims is not limited to these embodiments. Furthermore, the embodiments only provide some conditions for achieving this objective and do not imply that all conditions must be met to achieve this objective.

[0032] Example 1

[0033] Pr 0.5 Ba 0.5 Co 0.7 Fe 0.2 Ti 0.1 O 3-δ (PBCFT72) Electrode Material Preparation

[0034] Weigh out 4.3501 g of praseodymium nitrate hexahydrate, 2.6135 g of barium nitrate, 4.0744 g of cobalt nitrate hexahydrate, 1.6160 g of ferric nitrate nonahydrate, 0.5684 g of isopropyl titanate, and 12.6084 g of citric acid monohydrate, and dissolve them in deionized water. Add 11.6896 g of ethylenediaminetetraacetic acid and ammonia water, adjust the pH to 8, place the solution on a heated stirring table, and heat at 80°C to evaporate to a gel state. Heat the gel in a furnace until self-propagating combustion occurs to obtain a primary powder. Calcine the primary powder in a muffle furnace at 1100°C for 3 hours to obtain Pr. 0.5 Ba 0.5 Co 0.7 Fe 0.2 Ti 0.1 O 3-δ Powder.

[0035] Example 2

[0036] Pr 0.5 Ba 0.5 Co 0.5 Fe 0.4 Ti 0.1 O 3-δ (PBCFT54) Electrode Material Preparation

[0037] Weigh out 4.3501 g of praseodymium nitrate hexahydrate, 2.6135 g of barium nitrate, 2.9103 g of cobalt nitrate hexahydrate, 3.2309 g of ferric nitrate nonahydrate, 0.5684 g of isopropyl titanate, and 12.6084 g of citric acid monohydrate, dissolve them in deionized water, add 11.6896 g of ethylenediaminetetraacetic acid, add ammonia water, adjust the pH to 8, place the solution on a heated stirring table, heat at 80°C to evaporate to a gel state, heat the gel in a furnace until self-propagating combustion occurs to obtain the initial powder, calcine the initial powder in a muffle furnace at 1100°C for 3 hours to obtain Pr. 0.5 Ba 0.5 Co 0.5 Fe 0.4 Ti 0.1 O 3-δ Powder.

[0038] Example 3

[0039] Pr 0.5 Ba 0.5 Co 0.2 Fe 0.7 Ti 0.1 O 3-δ (PBCFT27) Electrode Material Preparation

[0040] Weigh out 4.3501 g of praseodymium nitrate hexahydrate, 2.6135 g of barium nitrate, 1.1641 g of cobalt nitrate hexahydrate, 5.6540 g of ferric nitrate nonahydrate, 0.5684 g of isopropyl titanate, and 12.6084 g of citric acid monohydrate, dissolve them in deionized water, add 11.6896 g of ethylenediaminetetraacetic acid, add ammonia water, adjust the pH to 8, place the solution on a heated stirring table, heat at 80°C to evaporate to a gel state, heat the gel in a furnace until self-propagating combustion occurs to obtain the initial powder, calcine the initial powder in a muffle furnace at 1100°C for 3 hours to obtain Pr. 0.5 Ba 0.5 Co 0.2 Fe 0.7 Ti 0.1 O 3-δ Powder.

[0041] Figure 1 The XRD patterns of the PBCFT72, PBCFT54, and PBCFT27 electrode materials prepared using the above method are shown. As can be seen from the figures, all three materials exhibit a cubic perovskite structure and are free of impurities.

[0042] Example 4

[0043] Electrode material resistance to CO2 poisoning test

[0044] The PBCFT72, PBCFT54, and PBCFT27 powders obtained in Examples 1, 2, and 3 were placed in a tube furnace and treated with 20% CO2-Ar at 800°C for 2 hours. The structural changes were then tested by XRD. The results are as follows: Figure 2 As shown in Figure a, none of the three samples showed significant structural changes or impurity phase formation after CO2 treatment.

[0045] Example 5

[0046] Preparation of a solid oxide electrolytic cell with PBCFT72-GDC cathode

[0047] Electrolyte powder La was dry-pressed. 0.8 Sr 0.2 Ga 0.8 Mg 0.2 O3 was pressed and sintered at 1450°C for 10 hours to obtain a sheet electrolyte; the PBCFT72 powder obtained in Example 1 and Gd were then added. 0.2 Ce 0.8 O 2-δ (GDC) powder and an ethyl cellulose-terpineol mixture with an ethyl cellulose content of 6 wt.% were mixed uniformly at a mass ratio of 0.75:0.75:1 to obtain PBCFT72-GDC electrode paste; the electrode paste was then coated onto La 0.8 Sr 0.2 Ga0.8 Mg 0.2 One side of the O3 electrolyte is coated with La, and the other side is coated with La. 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ (LSCF)-GDC slurry was calcined at 1100℃ for 2 hours to obtain an electrolytic cell with LSCF-GDC as the anode and PBCFT72-GDC as the cathode.

[0048] The electrolysis reaction was carried out at 800℃. The anode atmosphere was air, and the cathode atmosphere was a mixture of N2 and CO2 with a volume fraction of 5%. An electrochemical workstation was connected to test data such as impedance spectroscopy, linear sweep voltammetry curves, and chronoamperometry. The products were detected by online gas chromatography, and the Faraday efficiency was calculated.

[0049] like Figure 4 As shown, at 800℃ and 1.6V, the current density for CO2 electrolysis in an electrolytic cell with PBCFT-GDC as the cathode is 1.07 A cm⁻¹. -2 The polarization resistance is 0.32 Ωcm at 1.2V. 2 It exhibits good short-term stability and its Faraday efficiency is close to 100%.

[0050] Comparative Example 1

[0051] As a comparison with Example 4, Ba material, which contains no lanthanides at site A and no high-valence elements at site B, was treated with CO2 at 800°C in a tube furnace. 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3-δ (BSCF). For example... Figure 2 b. Freshly prepared BSCF also exhibits a cubic perovskite structure. However, after only one hour of treatment with 1% CO2-Ar, the BSCF structure was disrupted, resulting in impurity phases of CoO and BaCO3. This demonstrates that doping with lanthanides and high-valence elements can improve the chemical stability and CO2 poisoning resistance of Ba-based materials.

[0052] Using the same preparation method as in Example 5, an electrolytic cell with an LSCF-GDC anode and a BSCF-GDC cathode was prepared, and its CO2 reduction performance was tested. Figure 4 As shown, compared to BSCF-GDC, PBCFT72-GDC exhibits significantly improved CO2 electrolysis current density and stability, with a marked decrease in polarization resistance. This indicates that doping with lanthanides and high-valence elements can enhance the chemical stability and CO2 poisoning resistance of Ba-based materials, thereby improving their CO2 reduction performance as SOEC cathode materials.

[0053] Example 6

[0054] Preparation of a solid oxide electrolytic cell with PBCFT72-GDC anode

[0055] Electrolyte powder La was dry-pressed. 0.8 Sr 0.2 Ga 0.8 Mg 0.2 O3 was pressed and sintered at 1450℃ for 10 hours to obtain a sheet electrolyte; the PBCFT72 powder and GDC powder obtained in Example 1 were mixed with an ethyl cellulose-terpineol mixture with an ethyl cellulose content of 6 wt.% at a mass ratio of 0.75:0.75:1 to obtain a PBCFT72-GDC electrode paste. The electrode paste was coated on La 0.8 Sr 0.2 Ga 0.8 Mg 0.2 One side of the O3 electrolyte is coated with LSCF-GDC slurry, and the other side is calcined at 1100℃ for 2 hours to obtain an electrolytic cell with PBCFT72-GDC as the anode and LSCF-GDC as the cathode.

[0056] The electrolysis reaction was carried out at 800℃. The anode atmosphere was air, and the cathode atmosphere was a mixture of N2 and CO2 with a volume fraction of 5%. An electrochemical workstation was connected to test data such as impedance spectroscopy, linear sweep voltammetry curves, and chronoamperometry. The products were detected by online gas chromatography, and the Faraday efficiency was calculated.

[0057] like Figure 5 As shown, at 800℃ and 1.6V, the current density for CO2 electrolysis in an electrolytic cell using a PBCFT-GDC as the oxygen electrode is 1.0 A cm⁻¹. -2 The polarization resistance is 0.25 Ωcm at 1.2V. 2 It exhibits good short-term stability, with a Faraday efficiency approaching 100%. Electrochemical testing results show that this material also possesses catalytic activity for the oxygen evolution reaction.

[0058] The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the implementation. The scope of protection of the present invention should be determined by the scope defined in the claims. Other variations or modifications can be made based on the above description. Obvious variations or modifications derived therefrom are still within the scope of protection of the present invention.

Claims

1. A solid oxide electrolytic cell, characterized in that, The electrolytic cell includes a cathode, an anode, and an electrolyte; the anode and / or cathode is a Ba-based electrode material. The Ba-based electrode material has a cubic perovskite structure and the chemical formula Ln. 1-x Ba x M' 1-y M'' y O 3-δ , where 0 < x <1, 0< y <0.5, δ is the oxygen vacancy content, Ln is one or more of Pr, Ce, Yb, M' is one or more of Fe, Co, Ni, Cu, Zn, Mn, Cr, and M'' is one or more of V, Ti, Zr, Nb, Mo.

2. The solid oxide electrolytic cell according to claim 1, characterized in that, Ln is Pr, M' is Co and Fe, and M'' is Ti.

3. The solid oxide electrolytic cell according to claim 1, characterized in that, The preparation method of the Ba-based electrode material includes the following steps: (1) According to Ln 1-x Ba x M' 1-y M'' y O 3-δ The desired metal precursor is dissolved in water according to the stoichiometric ratio to obtain an aqueous solution of the metal salt. (2) Add the complexing agent to the aqueous solution of the metal salt obtained in step (1) to obtain a complexed sol; (3) The complexed sol obtained in step (2) is heated and stirred at 60-80 °C to evaporate and form a gel, followed by self-propagating combustion to obtain the initial powder; (4) Transfer the initial powder obtained in step (3) to a high-temperature furnace and calcine at 900-1100 ℃ for 2-5 hours to obtain the electrode material powder.

4. The solid oxide electrolytic cell according to claim 3, characterized in that, In step (1), the precursors of Ln, Ba, and M' are nitrates, the precursor of vanadium is ammonium metavanadate, the precursor of titanium is isopropyl titanate, the precursor of zirconium is zirconium oxynitrate, the precursor of niobium is niobium oxalate, and the precursor of molybdenum is ammonium molybdate.

5. The solid oxide electrolytic cell according to claim 3, characterized in that, The complexing agent in step (2) is one or more of citric acid, ammonium citrate, ethylenediaminetetraacetic acid, glycine, polyvinyl alcohol, and polyvinylpyrrolidone, and the ratio of the number of moles of the complexing agent to the total number of moles of metal ions is 1:1-3:

1.

6. The solid oxide electrolytic cell according to claim 1, characterized in that, The method for preparing the electrolytic cell includes the following steps: a. Electrolyte powder is shaped by dry pressing or casting, and then sintered at 1300-1500 ℃ for 5-10 hours to obtain sheet electrolyte; b. Grind and mix the Ba-based electrode material powder and the ion-conducting phase powder in a mortar, add the ethyl cellulose-terpineol mixture, and stir evenly to obtain the electrode slurry; c. Apply electrode paste evenly to the electrolyte surface using screen printing, brushing, or spin coating methods, and calcine at 1000-1200℃ for 2-5 hours. Apply electrode paste of the other electrode to the electrolyte surface in the same way to obtain a solid oxide electrolytic cell.

7. The solid oxide electrolytic cell according to claim 6, characterized in that: In step a, the electrolyte is yttrium-stabilized zirconium oxide or lanthanum gallate doped with yttrium oxide.

8. The solid oxide electrolytic cell according to claim 6, characterized in that: In step b, the mass ratio of Ba-based electrode material powder to ion-conducting phase powder is 70:30-30:70; the ion-conducting phase is Gd. 0.2 Ce 0.8 O 2-δ or Sm 0.2 Ce 0.8 O 2-δ The mass fraction of ethyl cellulose in the ethyl cellulose-terpineol mixture is 4-7 wt.%.

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