Composite perovskite electrode material and preparation method thereof

Abstract

The invention belongs to the technical field of electrode materials, and particularly relates to a composite perovskite electrode material and a preparation method thereof, nitrate or oxide corresponding to a metal element in a molecular formula is dissolved in a nitric acid solution, the solution is heated to prepare sol, then the sol is burnt, calcination is carried out under an oxygen-enriched condition, and finally the powdery electrode material is obtained. According to the multi-element doping method, the R-P type perovskite material with the heterostructure can be obtained, and a battery prepared from the material has good electrochemical performance and excellent stability.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrode materials, and particularly relates to a method for preparing a composite perovskite electrode material. Background Art

[0002] Solid oxide fuel cells (SOFCs) are considered a promising and efficient energy conversion technology that enables clean power generation by converting the chemical energy of fuels into electrical energy. However, due to the insufficient electrocatalytic activity and stability of air electrodes, their large-scale commercial application is severely restricted. Currently, the air electrode material used in oxygen ion conductor solid oxide fuel cells is LSCF (La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ ). Because LSCF has the property of a mixed ion conductor, it is also used in proton conductor solid oxide fuel cells. However, due to its single component and lack of proton conduction ability, the performance of the proton conductor solid oxide fuel cells configured with it is insufficient. Summary of the Invention

[0003] The present invention mainly provides an R-P type composite perovskite electrode material doped and modified based on PNO (Pr3Ni2O7), and a proton conductor solid oxide fuel cell prepared using this electrode material, in order to solve the problems of insufficient catalytic activity and poor stability of existing air electrode materials under high-temperature reduction conditions. The technical solution is as follows: A composite perovskite electrode material with the molecular formula Pr 3-x Ni 1.6 Fe 0.1-x Cu 0.1 Zn 0.1 Nb 0.1 O 7-x-δ +Pr x Fe x O 3-x-δ , where 0 < x < 0.1 and δ is the oxygen vacancy content, 0 < δ ≤ 2.

[0004] Furthermore, the molecular formula is Pr3Ni 1.6 Fe 0.1 Cu 0.1 Zn 0.1 Nb 0.1 O 7-δ .

[0005] Furthermore, it is prepared by electrospinning, sol-gel method or combustion method.

[0006] A preparation method for the above composite perovskite electrode material, comprising the following steps: (1) Dissolve the nitrate or oxide corresponding to the metal element in the molecular formula in nitric acid according to the stoichiometric ratio to obtain a solution containing metal cations; then, add citric acid and ethylenediaminetetraacetic acid to the solution containing metal cations to obtain a mixed solution. Adjust the pH of the mixed solution to neutral or weakly alkaline by adding ammonia dropwise, and stir thoroughly to obtain a sol. (2) The obtained sol is dried on a hot plate and burned to generate precursor powder; (3) The precursor powder is calcined in air atmosphere to obtain perovskite electrode material.

[0007] Furthermore, in step (1), the molar ratio of citric acid to metal cation is 1.2 to 1.8:1; and the molar ratio of citric acid to ethylenediaminetetraacetic acid is 1.2 to 1.8:1.

[0008] Furthermore, the pH of the mixed solution described in step (1) is adjusted to 7-8; the thorough stirring described in step (1) is stirring at room temperature until a sol is formed.

[0009] Furthermore, the temperature of the hot plate in step (2) is 200~300℃; the calcination in step (3) is carried out at 1100~1500℃ for 3~5 hours.

[0010] A battery made using the aforementioned composite perovskite electrode material.

[0011] Furthermore, it includes an air electrode, a fuel electrode, and an electrolyte disposed between the air electrode and the fuel electrode, all made from the composite perovskite electrode material.

[0012] Furthermore, the fuel electrode is made of Ni-BaCe. 0.7 Zr 0.1 Y 0.1 Yb 0.1 O 3-δ The coating thickness of the fuel electrode is 350~400μm; the electrolyte material is BaCe. 0.7 Zr 0.1 Y 0.1 Yb 0.1 O 3-δ The thickness of the electrolysis layer is 10~15μm.

[0013] By adopting the above scheme, the method of the present invention has the following advantages: This invention is the first to utilize the RP-type perovskite composite air electrode material Pr3Ni 1.6 Fe 0.1 Cu 0.1 Zn 0.1 Nb 0.1 O 7-δAs the air electrode of a proton conductor solid oxide fuel cell, the incorporation of Fe and Cu ions promotes the formation of oxygen vacancies, thereby enhancing O2 adsorption. In addition, the incorporation of Zn ions increases the proton conductivity of the air electrode, and the incorporation of Nb ions stabilizes the electrochemical structure of the air electrode. This provides a direction for developing efficient and stable air electrode materials for proton conductor solid oxide fuel cells.

[0014] The electrode material sample of this invention consists of interconnected small particles, forming a porous network structure. This porous structure has the potential to enhance the gas diffusion performance and interfacial reaction kinetics of the electrode material in a proton conductor solid oxide fuel cell.

[0015] The single cells prepared with the electrode material of the present invention exhibited relatively stable current densities after 100 hours of continuous operation at a high temperature of 600°C, and the current density remained essentially unchanged. This result demonstrates that the air electrode material of the present invention possesses excellent long-term stability.

[0016] The single cell prepared by this invention exhibits extremely high current density, indicating that multi-component doping significantly enhances the electrochemical performance of proton-conducting solid oxide fuel cells.

[0017] The electrochemical performance of the electrode material of this invention is enhanced by the synergistic effect of multiple elements. Each element is irreplaceable, and the absence of any one element will lead to a significant decrease in performance. Attached Figure Description

[0018] Figure 1 This is the X-ray diffraction pattern of the electrode material in Example 1; Figure 2 This is an HR-TEM image of the electrode material in Example 1; Figure 3 These are transmission electron microscope (TEM) images and corresponding EDX energy dispersive spectroscopy images of the electrode material in Example 1; Figure 4 This is a cross-sectional view of the battery made from the electrode material of Example 1; Figure 5 The EIS spectrum was obtained by testing the electrode material of Example 1 under open-circuit voltage in a pure H2 atmosphere at 700℃. Figure 6 The IV and IP test curves were obtained using the electrode material of Example 1 under a pure H2 atmosphere at 700°C. Figure 7 The IV and IP test curves were obtained using the electrode material of Example 1 under a pure H2 atmosphere at 700°C. Figure 8The graph shows the long-term stability test results obtained using the electrode material of Example 1 at 600°C and 0.8V. Detailed Implementation

[0019] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Example 1: (1) Based on the chemical formula Pr3Ni 1.6 Fe 0.1 Cu 0.1 Zn 0.1 Nb 0.1 O 7-δ According to the corresponding stoichiometric ratio, 0.081 g of ZnO was weighed and dissolved in 15 mL of nitric acid, which was taken as Zn 2+ The precursor was added, followed by 200 mL of water; 0.188 g of Cu(NO3)2, 0.404 g of Fe(NO3)3·9H2O, 1.164 g of Pr(NO3)3·6H2O, 4.653 g of Ni(NO3)2·6H2O and 0.303 g of (NH4)3Nb7(C2O4)3·3H2O were added to the system in sequence to obtain a solution containing metal cations; (2) Add 15.761g of citric acid (CA) and 14.612g of ethylenediaminetetraacetic acid (EDTA) to a solution containing metal cations as chelating agents and combustion agents, and set the molar ratio of CA, EDTA and total metal cations to 1.5:1:1; adjust the pH of the mixed solution to 7.0~8.0 by adding ammonia dropwise, and stir at room temperature for 12 hours to form a dark brown-green sol; (3) The obtained sol was dried on a hot plate at 300°C and burned to generate precursor powder; finally, the precursor powder was calcined at 1150°C for 5 hours in an air atmosphere to prepare the target perovskite electrode material (i.e., PNFCZN-PFO).

[0021] The X-ray diffraction pattern of the electrode material obtained in Example 1 is as follows: Figure 1 As shown in the figure, the obtained sample exhibits an impurity phase and a standard RP-type perovskite diffraction peak mode, consistent with a typical perovskite structure (space group 1 / 4 mm). This indicates that an RP-type perovskite material with a heterostructure has been successfully synthesized.

[0022] Figure 2The image shows an HR-TEM image of the electrode material from Example 1. It can be seen that the lattice spacing of the perovskite structure on the (111) plane is 0.346 nm and the lattice spacing on the (004) plane is 0.317 nm, corresponding to the XRD results. This confirms the successful synthesis of a perovskite material with a heterostructure.

[0023] Figure 3 The transmission electron microscope images show the particle size structure of the prepared sample. Figure 3 The corresponding EDX spectrum images show that Pr, Ni, Fe, Cu, Nb, Zn, and O are uniformly distributed in the sample of Example 1, with obvious enrichment of Pr, Fe, and O elements. This result further proves that the electrode material of the present invention contains PNFCZN (i.e., Pr 3-x Ni 1.6 Fe 0.1- x Cu 0.1 Zn 0.1 Nb 0.1 O 7-x-δ ) and PFO (i.e., Pr x Fe x O 3-x-δ Two phases.

[0024] Example 2: The difference from Example 1 is that the chemical formula described in step (1) is Pr3Ni. 1.6 Fe 0.15 Cu 0.1 Zn 0.0 5Nb 0.1 O 7-δ The amount of Fe(NO3)3·9H2O added was 0.606g; the amount of ZnO added was 0.0405g.

[0025] Comparative Example: The difference from Example 1 is that the chemical formula described in step (1) is Pr3Ni. 1.6 Fe 0.2 Cu 0.1 Nb 0.1 O 7-δ The amount of Fe(NO3)3·9H2O added was 0.808g.

[0026] Example Sample Testing: Using polyvinyl alcohol (5% PVA) as a binder, BaCe was placed in a mortar. 0.7 Zr 0.1 Y 0.1 Yb 0.1 O 3-δThe powder and NiO powder were mixed at a mass ratio of 4:6, and 10% of the total mass of microcrystalline cellulose was added as a pore-forming agent. The three materials were then uniformly ground. Subsequently, the ground powder was mixed with the electrolyte powder BaCe. 0.7 Zr 0.1 Y 0.1 Yb 0.1 O 3-δ The material was dry-pressed into discs at 250 MPa and sintered at 1350 °C for 5 hours to form a dense electrolyte structure, ensuring good conductivity and mechanical stability. Next, to prepare the air electrode, the target powder was thoroughly mixed with a binder (6% ethyl cellulose and 94% terpineol) in a mortar to form a uniform slurry. The electrode materials obtained in Example 1 and the comparative example were used as air electrodes to prepare slurries, which were then uniformly coated onto BaCe. 0.7 Zr 0.1 Y 0.1 Yb 0.1 O 3-δ The electrolyte disc is placed on the other side and sintered at 1000°C for 3 hours (heating rate of 3°C / min) to form a single cell structure.

[0027] Figure 4 The diagram shows the battery structure configured with the electrode material of Example 1. The diagram illustrates that both the air electrode and the fuel electrode exhibit porous structures. This demonstrates that the electrode material prepared using the method of this invention can form a uniform porous network structure. Even with the pore expansion effect of the binder, the uniformity of the pores and the stability of the network structure are still maintained. This morphology facilitates gas diffusion to the electrochemical reaction interface.

[0028] To investigate the electrochemical performance of single cells, the air electrode was positioned upwards and sealed within an alumina tube using ceramic sealant to ensure good airtightness. The experimental setup was placed in a heating furnace, and the test temperature was adjusted to 700°C. During the high-temperature heating process, pure H2 gas (flow rate 20 mL / min) was introduced through the fuel electrode side, while the air electrode side was directly exposed to ambient air. Electrochemical tests were performed using an Autolab electrochemical workstation, and performance evaluations were conducted on single cells equipped with the air electrodes of Example 1 and the comparative example. 5 Hz to 10 -1 Electrochemical impedance spectroscopy (EIS) was recorded in the frequency range of Hz. Current-voltage (IV) curves were obtained by scanning from 0V to 1.0V at a scan rate of 10mV / s. The long-term stability of the single cell was tested under a constant voltage of 0.85V to further verify the cell performance and system stability.

[0029] Figure 5The EIS spectrum obtained by testing at 700°C in a pure H2 atmosphere with open-circuit voltage using the PNFCZN-PFO air electrode from Example 1 is shown. The impedance spectrum consists of a semicircle and is divided into ohmic impedance (R0). Ω ) and polarization impedance (R p Ohmic impedance is the first x-intercept of the semicircular spectrum in the high-frequency region, and it is typically related to ion conduction through the electrolyte, electronic conduction within the battery assembly, and contact resistance. Polarization impedance, on the other hand, is calculated by subtracting the ohmic impedance from the total resistance estimated using the second x-intercept of the spectrum in the low-frequency region. This is attributed to charge transfer reactions and mass transfer steps at the interface between the electrodes and the electrolyte. Figure 5 It can be seen that the single-cell polarization impedance of the PNFCZN-PFO air electrode of Example 1 exhibits extremely low polarization impedance, indicating that the electrode material prepared by the present invention has strong catalytic activity.

[0030] Figure 6 The IV and IP curves are obtained by testing with the PNFCZN-PFO air electrode from Example 1 under a pure H2 atmosphere at 700°C. Figure 6 It can be seen that the single cell equipped with the PNFCZN-PFO air electrode of Embodiment 1 exhibits a high power density, reaching 1.29 W / cm² at 700°C. 2 This indicates that multi-component doping significantly enhances the electrochemical performance of P-SOFCs.

[0031] Figure 7 The figures show the IV and IP test curves obtained using the air electrode material of Example 3 under a pure H2 atmosphere at 700°C. The comparative example does not contain Zn and has a relatively high iron content, which is equivalent to replacing zinc with iron. As can be seen from the figures, the power density of the single cell made from the electrode material of the comparative example is significantly lower than that of Example 1, indicating that the selection of each element in the electrode material of the present invention is indispensable and cannot be simply replaced; the absence of any element will lead to a significant deterioration in the material performance.

[0032] Figure 8 Long-term durability performance of single cells using the electrode material of Example 1 was tested at 0.85V and 600°C. After 100 hours of continuous operation, the electrolytic current density of the single cells showed relatively stable characteristics with minimal degradation. Notably, compared to the initial current density, the degradation of single cells using the electrode material of this invention was virtually nonexistent. This result indicates that the multi-doped RP-type perovskite air electrode with a heterostructure exhibits good long-term stability during battery power generation.

[0033] For those skilled in the art, various other corresponding changes and modifications can be made based on the technical solutions and concepts described above, and all such changes and modifications should fall within the protection scope of the claims of this invention.

Claims

1. A composite perovskite electrode material, characterized in that, Molecular formula is Pr 3-x Ni 1.6 Fe 0.1-x Cu 0.1 Zn 0.1 Nb 0.1 O 7-x-δ + Pr x Fe x O 3-x-δ wherein 0 < x < 0.1 and δ is the oxygen vacancy content, 0 < δ ≤ 2.

2. The composite perovskite electrode material of claim 1, wherein Molecular formula is Pr3Ni 1.6 Fe 0.1 Cu 0.1 Zn 0.1 Nb 0.1 O 7-δ .

3. The composite perovskite electrode material of claim 1, wherein, The composite perovskite electrode material is prepared by electrostatic spinning, sol-gel method or combustion method.

4. A method for preparing the composite perovskite electrode material according to any one of claims 1 to 3, characterized in that The method comprises the following steps: (1) according to the stoichiometric ratio, the nitrate or oxide corresponding to the metal element in the molecular formula is dissolved in nitric acid to obtain a solution containing metal cations; then, citric acid and ethylenediaminetetraacetic acid are added to the solution containing metal cations to obtain a mixed solution, the pH of the mixed solution is adjusted to neutral or weak alkaline by adding ammonia water dropwise, and the mixed solution is fully stirred to obtain a sol; (2) the obtained sol is dried on a hot plate and combusted to generate a precursor powder; (3) the precursor powder is calcined in an air atmosphere to obtain a perovskite electrode material.

5. The method for preparing the composite perovskite electrode material according to claim 4, characterized in that, The mass ratio of citric acid to metal cations in step (1) is 1.2-1.8:1; the mass ratio of citric acid to ethylenediaminetetraacetic acid is 1.2-1.8:

1.

6. The method for preparing the composite perovskite electrode material according to claim 4, characterized in that, The pH of the mixed solution in step (1) is adjusted to 7-8; the fully stirring in step (1) is stirring at room temperature until the sol is formed.

7. The method for preparing the composite perovskite electrode material according to claim 4, characterized in that, The temperature of the hot plate in step (2) is 200-300℃; the calcination in step (3) is calcination at 1100-1500℃ for 3-5h.

8. A battery prepared by using the composite perovskite electrode material according to any one of claims 1-3.

9. The battery of claim 8, wherein, The air electrode, the fuel electrode and the electrolyte arranged between the air electrode and the fuel electrode are prepared by using the composite perovskite electrode material.

10. The battery of claim 8, wherein, The fuel electrode uses Ni-BaCe 0.7 Zr 0.1 Y 0.1 Yb 0.1 O 3-δ The coating thickness of the fuel electrode is 350-400 μm; the electrolyte material is BaCe 0.7 Zr 0.1 Y 0.1 Yb 0.1 O 3-δ The thickness of the electrolyte is 10-15 μm.

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