Preparation and application of a multi-stage structure composite electrode material

Abstract

The application discloses preparation and application of a multi-level structure composite electrode material. The electrode material comprises a perovskite-fluorite structure oxide and nanoparticles; the chemical formula of the perovskite-fluorite structure oxide is Pr 1‑x Ba x Co 1‑y‑z Fe y Ti z O 3‑δ ‑Ln 0.2 Ce 0.8 O 2‑δ , wherein Ln=Gd, Sm, La, 0 3‑δ <0.5, and the oxygen vacancy content is δ; the loading of the nanoparticles is 0-10 wt.%, and the end value 0 is excluded. The electrode material has a multi-level nanostructure, can effectively expand a three-phase interface, increase reaction sites, has good conductivity and CO2 poisoning resistance, and has catalytic activity of both oxygen evolution reaction and carbon dioxide reduction reaction, and can be used as both an anode material and a cathode electrode material of a SOEC.

Description

Technical Field

[0001] This invention belongs to the field of solid oxide battery technology, specifically relating to the preparation and application of a multi-level structure composite electrode material. Background Technology

[0002] Currently, fossil fuels such as coal, oil, and natural gas remain the mainstay of the global energy structure, and current carbon dioxide emissions primarily originate from their use. Carbon dioxide is one of the main culprits of the greenhouse effect, and the increasing emissions have led to increasingly severe climate problems, with frequent extreme weather events such as high temperatures, floods, and droughts. However, the use of fossil fuels cannot be completely replaced for a long time, making the effective utilization of already emitted carbon dioxide a pressing issue. Solid oxide electrolyzers (SOECs) are energy conversion devices that convert electrical and thermal energy into chemical energy. They can electrolyze CO2 to produce CO, and can also combine with reactions such as water electrolysis, methane coupling, partial methane oxidation, and ethane dehydrogenation to produce important chemical raw materials such as hydrogen, ethane, and ethylene. Furthermore, the electrical and thermal energy required for SOEC operation can be provided by renewable energy sources and industrial waste heat, making it more economical, efficient, and environmentally friendly.

[0003] In solid oxide electrolyzers, electrode materials are one of the key components. Commonly used electrode materials include Ni-YSZ or perovskite-fluorite composites. Perovskite-fluorite composites have received widespread attention in recent years due to their superior resistance to carbon deposition and compatibility with most electrolyte materials. Typically, perovskite materials provide electronic conductivity and catalytic activity, while fluorite materials provide ionic conductivity. The interface between the electronically conductive phase, the ionicly conductive phase, and the gas phase is the site where the electrolysis reaction occurs, known as the three-phase boundary (TPB). Insufficient three-phase boundary conditions are often a key factor limiting the catalytic reaction rate. Summary of the Invention

[0004] This invention provides a solid oxide electrolytic cell electrode material and its preparation method. The electrode material is an electron-ion mixed conductor with a multi-level nanostructure, which can effectively expand the three-phase interface, increase reaction sites, and has good conductivity and CO2 poisoning resistance. It also has catalytic activity for both oxygen evolution reaction and carbon dioxide reduction reaction, and can be used as both an anode material and a cathode electrode material for SOEC.

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

[0006] This invention provides a multi-level composite electrode material, comprising a perovskite-fluorite oxide and nanoparticles; the perovskite-fluorite oxide has the chemical formula Pr 1-x Ba x Co1-y-z Fe y Ti z O 3-δ -Ln 0.2 Ce 0.8 O 2-δ (PBCFT-LnDC), where Ln = Gd, Sm, La, 0 < x < 1, 0 < y < 1, 0 < z < 0.5, δ is the oxygen vacancy content, and the chemical formula of the nanoparticles is PrCoO 3-δ (PC), with δ being the oxygen vacancy content; the loading of the nanoparticles is 0 - 10 wt.%, by mass fraction, and does not include the endpoint value 0.

[0007] In the above technical solution, further, the electrode material is PrCoO 3-δ / Pr 0.5 Ba 0.5 Co 0.7 Fe 0.2 Ti 0.1 O 3-δ -Gd 0.2 Ce 0.8 O 2-δ (PC / PBCFT721-GDC).

[0008] In the above technical solution, further, the loading of the electrode material nanoparticles is 6 wt.%.

[0009] In the above technical solution, further, the average particle size of the carrier skeleton is 100 nm - 1 μm.

[0010] In the above technical solution, further, the average particle size of the nanoparticles is 10 - 100 nm.

[0011] On the other hand, the present invention provides a method for preparing the above composite electrode material, and the method includes the following steps:

[0012] (1) According to the stoichiometric ratio of Pr 1-x Ba x Co 1-y-z Fe y Ti z O 3-δ , dissolve the praseodymium precursor, barium precursor, cobalt precursor, iron precursor and titanium precursor in water, add a complexing agent to form a mixed solution, heat and stir to evaporate at 60 - 80 °C to form a sol, then self-propagating combustion occurs to obtain a primary powder, transfer it to a high-temperature furnace and calcine at 800 - 1100 °C for 2 - 5 h to obtain Pr 1- x Ba x Co 1-y-z Fe y Ti z O3-δ powder;

[0013] (2) According to Ln 0.2 Ce 0.8 O 2-δ According to the stoichiometric ratio, Ln precursor and cerium precursor are dissolved in water, and a complexing agent is added to form a mixed solution. The solution is heated and stirred at 60-80℃ to evaporate and form a sol. Subsequently, self-propagating combustion occurs to obtain the initial powder, which is then transferred to a high-temperature furnace and calcined at 800-1100℃ for 2-5 hours to obtain Ln. 0.2 Ce 0.8 O 2-δ powder

[0014] (3) Take the Pr obtained in step (1) 1-x Ba x Co 1-y-z Fe y Ti z O 3-δ Powder and Ln obtained in step (2) 0.2 Ce 0.8 O 2-δ The powders were ground and mixed at a mass ratio of 30:70-70:30, and then the ethyl cellulose-terpineol mixture was added and stirred evenly to obtain an ink-like paste.

[0015] (4) The slurry obtained in step (3) is uniformly coated on the surface of the electrolyte by screen printing, brushing or spin coating, and calcined at 1000-1200℃ for 2-5 hours to obtain a perovskite-fluorite structure oxide framework.

[0016] (5) According to PrCoO 3-δ According to the stoichiometric ratio, praseodymium precursor and cobalt precursor are dissolved in water to obtain impregnation solution;

[0017] (6) The impregnation solution obtained in step (5) is impregnated into the perovskite-fluorite structure oxide framework obtained in step (4), and calcined in air at 800°C for 0.5-3 hours to obtain the multi-level structure composite electrode material.

[0018] In the above technical solution, further, in step (1), the praseodymium precursor is praseodymium nitrate, the barium precursor is barium nitrate, the cobalt precursor is cobalt nitrate, the iron precursor is ferric nitrate, and the titanium precursor is isopropyl titanate; the complexing agent is at least one of citric acid, ammonium citrate, ethylenediaminetetraacetic acid, glycine, and polyvinyl alcohol; 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.

[0019] In the above technical solution, further, in step (2), the Ln precursor is nitrate, the cerium precursor is cerium nitrate; the complexing agent is at least one of citric acid, ammonium citrate, ethylenediaminetetraacetic acid, glycine, and polyvinyl alcohol; 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.

[0020] In the above technical solution, further, in step (2), Ln 0.2 Ce 0.8 O 2-δ The powder can be prepared by the above method, or it can be a commercially available powder.

[0021] In the above technical solution, further, in step (3), the mass fraction of ethyl cellulose in the ethyl cellulose-terpineol mixture is 4-7 wt.%.

[0022] In the above technical solution, further, in step (4), the electrolyte is yttrium-stabilized zirconium oxide or lanthanum gallate doped with lanthanum.

[0023] In the above technical solution, further, in step (5), the praseodymium precursor is praseodymium nitrate and the cobalt precursor is cobalt nitrate.

[0024] In another aspect, the present invention provides an application of the above-mentioned composite electrode material as an anode material and / or cathode material in a solid oxide electrolytic cell.

[0025] The beneficial effects of this invention are as follows:

[0026] The electrode material of this invention has a multi-level nanostructure, which can effectively expand the three-phase interface, increase reaction sites, and has good electrical conductivity and CO2 poisoning resistance. It also has catalytic activity for both oxygen evolution reaction and carbon dioxide reduction reaction, and can be used as both an anode material and a cathode electrode material for SOEC.

[0027] In the preparation process of this invention, the calcination temperature of the impregnation solution is the same as the electrolytic reaction temperature, which can be combined with the heating process of the electrolytic cell, simplifying the process and improving energy utilization efficiency. Attached Figure Description

[0028] Figure 1 The images show the XRD patterns of PC / PBCFT721-GDC and PC / PBCFT721 electrode materials, where a is PC / PBCFT721-GDC and b is PC / PBCFT721.

[0029] Figure 2The surface morphology of the PC / PBCFT721-GDC electrode material is shown in the figures, where a is PBCFT721-GDC, b is 3% PC / PBCFT721-GDC, c is 6% PC / PBCFT721-GDC, and d is 9% PC / PBCFT721-GDC.

[0030] Figure 3 The high-temperature OER performance of PC / PBCFT721-GDC as an anode material is shown in Figure a, where a is the linear sweep voltammetry curve, b is the chronoamperometry and Faraday efficiency, and c is the electrochemical impedance spectroscopy.

[0031] Figure 4 The CO2 reduction performance of PC / PBCFT721-GDC as the cathode material is shown in Figure a, where a is the linear sweep voltammetry curve, b is the chronoamperometry and Faraday efficiency, and c is the electrochemical impedance spectroscopy. Detailed Implementation

[0032] 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.

[0033] Example 1

[0034] 6% PrCoO 3-δ / Pr 0.5 Ba 0.5 Co 0.7 Fe 0.2 Ti 0.1 O 3-δ -Gd 0.2 Ce 0.8 O 2-δ The preparation of (6% PC / PBCFT721-GDC) electrode material includes the following steps:

[0035] (1) Weigh 4.3501g of praseodymium nitrate hexahydrate, 2.6135g of barium nitrate, 4.0744g of cobalt nitrate hexahydrate, 1.6160g of ferric nitrate nonahydrate, 0.5684g of isopropyl titanate, and 12.6084g of citric acid monohydrate and dissolve them in deionized water. Add 11.6896g of ethylenediaminetetraacetic acid and ammonia water to adjust the pH to 8 to form a mixed solution. Place the mixed solution on a heating and stirring table and heat it at 80°C to evaporate it into a gel. Heat the gel in a heating furnace until it undergoes self-propagating combustion to obtain the initial powder. Calcine the initial powder in a muffle furnace at 1100°C for 3 hours to obtain PBCFT721 powder.

[0036] (2) Weigh 2.2568g of gadolinium nitrate hexahydrate, 8.6844g of cerium nitrate hexahydrate, and 7.8803g of citric acid monohydrate and dissolve them in deionized water. Add 7.3060g of ethylenediaminetetraacetic acid and ammonia water to adjust the pH to 8 to form a mixed solution. Place the mixed solution on a heating and stirring table and heat it at 80°C to evaporate it into a gel. Heat the gel in a heating furnace until it undergoes self-propagating combustion to obtain the initial powder. Calcine the initial powder in a muffle furnace at 800°C for 2 hours to obtain GDC powder.

[0037] (3) Weigh 0.5g of PBCFT721 powder and 0.5g of GDC powder, grind and mix them evenly, add 6wt.% ethyl cellulose-terpineol mixture, stir and mix evenly to form an ink-like slurry, and apply it to La 0.8 Sr 0.2 Ga 0.8 Mg 0.2 The PBCFT721-GDC electrode was obtained by calcining the O3 electrolyte surface in a muffle furnace at 1100℃ for 2 hours.

[0038] (4) Weigh 2.1750g of praseodymium nitrate hexahydrate and 1.4551g of cobalt nitrate hexahydrate, dissolve them in deionized water and make up to 50ml to obtain 0.1M PC impregnation solution;

[0039] (5) PC impregnation solution was impregnated onto the surface of PBCFT721-GDC electrode by impregnation method until the predetermined loading was reached, and PC nanoparticles were generated in situ by calcination at 800℃ for 2h.

[0040] Figure 1 XRD patterns of PC / PBCFT721-GDC and PC / PBCFT721 electrode materials. Figure 1 a represents the PC / PBCFT721-GDC electrode material prepared using the method provided in this invention. Since the main peak of PC overlaps with that of GDC, making it difficult to observe the PC peak, the PC / PBCFT721 electrode material was prepared using the same method. Its XRD pattern is shown below. Figure 1 b. As can be seen from the figure, the PC peak shows an increase in strength as the impregnation amount increases.

[0041] Figure 2The figures show the surface morphology of the PC / PBCFT721-GDC electrode material, where a represents PBCFT721-GDC, b represents 3% PC / PBCFT721-GDC, c represents 6% PC / PBCFT721-GDC, and d represents 9% PC / PBCFT721-GDC. As can be seen from the figures, the nanoparticles in the 3% impregnation sample are unevenly covered, with some of the support surface exposed. In the 6% sample, PC consists of uniformly distributed nanoparticles that evenly cover the PBCFT-GDC oxide support. However, in the 9% sample, the PC particles show significant agglomeration and growth, which may lead to a reduction in the three-phase interface and blockage of gas diffusion channels.

[0042] Example 2

[0043] Application of PC / PBCFT721-GDC electrode material as SOEC anode

[0044] A PC / PBCFT721-GDC|LSGM half-cell was fabricated according to the steps described in Example 1, with La coated on the other side of the LSGM electrolyte sheet. 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ -Gd 0.2 Ce 0.8 O 2-δ The (LSCF-GDC) electrode paste was calcined in a muffle furnace at 1100℃ for 2 hours to obtain a full cell, with PC / PBCFT721-GDC as the anode and LSCF-GDC as the cathode. Gold paste was coated onto the electrode surface as the current collector. The cell was placed in a self-made tubular reactor, with a 5% N2 volume fraction N2 and CO2 mixture passed through the cathode chamber, while the anode chamber was exposed to air. The temperature was raised to 800℃, and an electrochemical workstation was connected to measure impedance spectroscopy, linear sweep voltammetry, chronoamperometry, etc. Online gas chromatography was used to detect the products, and the Faraday efficiency was calculated.

[0045] Figure 3 The electrolysis performance of CO2 in a solid oxide electrolyzer using PC / PBCFT721-GDC as the anode material was analyzed. It can be seen that the electrolysis current density of PBCFT721-GDC impregnated with PC is significantly improved, with the highest current density (1.43 A cm⁻¹) observed in 6% PC / PBCFT721-GDC. -2 It represents a 43% improvement over the PBCFT721-GDC. Figure 3 The chronoamperometry results for b show that the short-time stability of the electrode material is also improved after impregnation with PC, and the Faraday efficiency of each sample group is close to 100%. Figure 3 According to the electrochemical impedance spectroscopy results of c, the polarization resistance of the electrode decreased significantly after impregnation with PC.

[0046] Example 3

[0047] Application of PC / PBCFT721-GDC electrode material as SOEC cathode

[0048] A PC / PBCFT721-GDC|LSGM half-cell was prepared according to the steps described in Example 1. An LSCF-GDC electrode paste was coated on the other side of the LSGM electrolyte sheet. The cells were then calcined in a muffle furnace at 1100°C for 2 hours to obtain a full cell. The LSCF-GDC electrode was used as the anode, and the PC / PBCFT721-GDC electrode as the cathode. Gold paste was coated onto the electrode surface as a current collector. The cell was placed in a self-made tubular reactor. A mixture of N2 and CO2 with a volume fraction of 5% (N2) was introduced into the cathode chamber, while the anode chamber was exposed to air. The temperature was raised to 800°C, and an electrochemical workstation was connected to test impedance spectroscopy, linear sweep voltammetry, chronoamperometry, etc. The products were detected using online gas chromatography, and the Faraday efficiency was calculated.

[0049] Figure 4 The electrolysis performance of CO2 in a solid oxide electrolytic cell using PC / PBCFT721-GDC as the cathode material was analyzed. It can be seen that the electrolysis current density of PBCFT721-GDC impregnated with PC is significantly improved, with the highest current density (1.37 A cm⁻¹) observed in 6% PC / PBCFT721-GDC. -2 It represents a 29% improvement over the PBCFT721-GDC. Figure 4 The chronoamperometry results for b show that the short-time stability of the electrode material is slightly improved after impregnation with PC, and the Faraday efficiency of each sample group is close to 100%. From Figure 4 According to the electrochemical impedance spectroscopy results of c, the polarization resistance of the electrode decreased significantly after impregnation with PC.

[0050] 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 multi-level composite electrode material, characterized in that, The electrode material comprises a perovskite-fluorite oxide framework and nanoparticles; the chemical formula of the perovskite-fluorite oxide framework is Pr. 1-x Ba x Co 1-y- z Fe y Ti z O 3-δ -Ln 0.2 Ce 0.8 O 2-δ Where Ln = Gd, Sm, La, 0 < x <1, 0< y <1, 0< z <0.5, δ represents the oxygen vacancy content, and the chemical formula of the nanoparticles is PrCoO. 3-δ δ represents the oxygen vacancy content; the loading of the nanoparticles is expressed as a mass fraction of 0-10 wt.%, excluding the endpoint value of 0. The electrode material serves as the anode material and / or cathode material in a solid oxide electrolytic cell during the electrolysis of carbon dioxide.

2. The composite electrode material according to claim 1, characterized in that, The average particle size of the perovskite-fluorite structured oxide framework is 100 nm-1 μm.

3. The composite electrode material according to claim 1, characterized in that, The average particle size of the nanoparticles is 10-100 nm.

4. A method for preparing the composite electrode material according to any one of claims 1-3, characterized in that, The preparation method of the electrode material includes the following steps: (1) According to Pr 1-x Ba x Co 1-y-z Fe y Ti z O 3-δ According to the stoichiometric ratio, praseodymium precursor, barium precursor, cobalt precursor, iron precursor, and titanium precursor were dissolved in water, and a complexing agent was added to form a mixed solution. The solution was heated and stirred at 60-80 °C to evaporate and form a sol. Subsequently, self-propagating combustion occurred to obtain the initial powder, which was then transferred to a high-temperature furnace and calcined at 800-1100 °C for 2-5 h to obtain Pr. 1- x Ba x Co 1-y-z Fe y Ti z O 3-δ powder; (2) According to Ln 0.2 Ce 0.8 O 2-δ According to the stoichiometric ratio, Ln precursor and cerium precursor are dissolved in water, and a complexing agent is added to form a mixed solution. The solution is heated and stirred at 60-80 °C to evaporate and form a sol. Subsequently, self-propagating combustion occurs to obtain the initial powder, which is then transferred to a high-temperature furnace and calcined at 800-1100 °C for 2-5 h to obtain Ln. 0.2 Ce 0.8 O 2-δ powder; (3) Take the Pr obtained in step (1) 1-x Ba x Co 1-y-z Fe y Ti z O 3-δ Powder and Ln obtained in step (2) 0.2 Ce 0.8 O 2-δ The powders were ground and mixed at a mass ratio of (30:70) to (70:30), and an ethyl cellulose-terpineol mixture was added and stirred evenly to obtain an ink-like paste. (4) The slurry obtained in step (3) is uniformly coated on the surface of the electrolyte by screen printing, brushing or spin coating, and calcined at 1000-1200 ℃ for 2-5 h to obtain the perovskite-fluorite structure oxide framework. (5) According to PrCoO 3-δ According to the stoichiometric ratio, praseodymium precursor and cobalt precursor are dissolved in water to obtain impregnation solution; (6) The impregnation solution obtained in step (5) is impregnated into the perovskite-fluorite structure oxide framework obtained in step (4), and calcined in air at 800 °C for 0.5-3 h to obtain the multi-level structured composite electrode material.

5. The preparation method according to claim 4, characterized in that, In step (1), the praseodymium precursor is praseodymium nitrate, the barium precursor is barium nitrate, the cobalt precursor is cobalt nitrate, the iron precursor is ferric nitrate, and the titanium precursor is isopropyl titanate; the complexing agent is at least one of citric acid, ammonium citrate, ethylenediaminetetraacetic acid, glycine, and polyvinyl alcohol; 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 preparation method according to claim 4, characterized in that, In step (2), the Ln precursor is nitrate, the cerium precursor is cerium nitrate; the complexing agent is at least one of citric acid, ammonium citrate, ethylenediaminetetraacetic acid, glycine, and polyvinyl alcohol; 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.

7. The preparation method according to claim 4, characterized in that, In step (3), the mass percentage of ethyl cellulose in the ethyl cellulose-terpineol mixture is 4-7%.

8. The preparation method according to claim 4, characterized in that, In step (4), the electrolyte is yttrium oxide-stabilized zirconium oxide (YSZ) or doped lanthanum gallate.

9. The preparation method according to claim 4, characterized in that, In step (5), the praseodymium precursor is praseodymium nitrate and the cobalt precursor is cobalt nitrate.

10. An application of the composite electrode material according to any one of claims 1-3, characterized in that, As an anode material and / or cathode material in a solid oxide electrolytic cell during the electrolysis of carbon dioxide.

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