Doping type biphase oxygen electrode material based on in-situ reconstruction and preparation method and application thereof

Abstract

The invention belongs to the technical field of solid oxide batteries, and relates to a doped biphase oxygen electrode material based on in-situ reconstruction and a preparation method and application thereof. The doping type biphase oxygen electrode material based on in-situ reconstruction is a perovskite type oxide, and the chemical formula is PrBaCo < 2-x-y-z > M < 1 > < x > Y < z > M < 2 > < y > O < 5 + delta >, in the formula, M1 is any one of Zr, Hf and Ti, M2 is any one of Nb, Mo, Ta and V, x is greater than or equal to 0.05 and less than or equal to 0.15, y is greater than or equal to 0.05 and less than or equal to 0.15, z is greater than or equal to 0.05 and less than or equal to 0.2, and delta represents a non-stoichiometric oxygen vacancy. The doped oxygen electrode material with a biphase structure is prepared by co-doping M1, M2 and Y according to a specific proportion to partially replace Co at the position B, and the oxygen electrode material has a relatively low thermal expansion coefficient and is well matched with an electrolyte BCZYYb. The oxygen electrode material has good electrochemical performance and excellent long-term working stability.

Description

Technical Field

[0001] This invention belongs to the field of solid oxide battery technology, specifically relating to doped biphase oxygen electrode materials based on in-situ reconstruction, their preparation methods, and applications. Background Technology

[0002] Due to their high efficiency, low emissions, and bidirectional energy conversion characteristics, reversible protonic cavities (R-PCCs) have become a clean energy generation and long-term energy storage technology with enormous application potential. They can operate as either protonic cavities fuel cells or protonic cavities electrolyzers. Compared to traditional oxygen ion conductors, proton conductors exhibit higher ionic conductivity and lower electronic conductivity in the medium-low temperature range (350-700℃), and proton conduction between two adjacent oxygen atoms has a low activation energy (0.4-0.6 eV). R-PCCs consist of a hydrogen electrode (anode), an electrolyte, and an oxygen electrode (cathode). With breakthroughs in the research and development of electrolyte and hydrogen electrode materials, BaCe... 0.7 Zr 0.1 Y 0.1 Yb 0.1 O 3-δ (BCZYYb) and BCZYYb-NiO are considered relatively mature proton-conducting electrolyte and hydrogen electrode materials, respectively. As the core component of R-PCCs, the performance of the oxygen electrode directly determines the kinetic efficiency of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), thus affecting the overall energy conversion efficiency and cycle stability. Although extensive research has been conducted on oxygen electrodes, the commercialization of R-PCCs is limited by the slow kinetics of proton-related ORR and OER, the high coefficient of thermal expansion (TEC), and the limited stability of oxygen electrode materials. Therefore, developing oxygen electrode materials with high ORR and OER activity, low TEC, and excellent durability is crucial for the advancement of R-PCC technology.

[0003] Cobalt-based perovskite materials are widely used as oxygen electrode materials in R-PCCs due to their high catalytic activity in promoting ORR and OER. However, the coefficient of thermal expansion (TEC) of conventional cobalt-based perovskite materials remains relatively high; for example, Ba... 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3-δ (BSCF), PrBa 0.5 Sr 0.5 Co 1.5 Fe 0.5 O5+δ (PBSCF) and BaCo 0.4 Fe 0.4 Zr 0.1 Y 0.1 O 3-δ The coefficients of thermal expansion of (BCFZY) are 23.2 × 10⁻⁶. -6 K -1 23.7×10 -6 K -1 21.6×10 -6 K -1 (Advanced Functional Materials 29(37)(2019), 1903805; Applied Physics Reviews 7(1)(2020), 011314). Therefore, these materials are similar to the commonly used proton-conducting electrolyte BCZYYb (approximately 12.0 × 10⁻⁶). -6 K -1 The TEC mismatch between the oxygen electrode material and the electrolyte can lead to excessive thermal stress during battery operation, causing interface delamination and resulting in poor battery stability and significant performance degradation. To improve the TEC matching between the oxygen electrode material and the electrolyte, it is generally necessary to mechanically mix the single-phase perovskite material and the electrolyte material to form a composite oxygen electrode or to dope the perovskite material with elements. However, the mechanical mixing method cannot establish a sufficiently effective interface between the two components, that is, the interaction between the electrodes is weak, so the problems of battery stability and significant degradation still exist; in addition, the performance of the single-phase oxygen electrode is limited by the limited ion transport channels and the small number of active sites. Element doping is an in-situ synthesis method, which is not only conducive to establishing a stable and effective interface, but also conducive to increasing the oxygen vacancy concentration of the material. However, in the existing technology, Zn, Ni or Mn elements are generally used to replace Co at the B site for single doping or double doping. For example, Wang Q et al. (Journal of Materials Chemistry A, 2020, 8(16):7704-7712) prepared Pr2BaNiMnO by replacing Co and Fe at the B site with Ni and Mn. 7-δ The obtained Pr2BaNiMnO 7-δ Although it has a low TEC, its TEC compatibility with the high-performance electrolyte BCZYYb still needs to be improved. Summary of the Invention

[0004] Given the high coefficient of thermal expansion (TEC) of conventional cobalt-based perovskite oxygen electrode materials in existing technologies, their poor TEC matching with the commonly used proton-conductive electrolyte BCZYYb, and the persistent issues of battery stability and degradation, this invention provides a doped biphase oxygen electrode based on in-situ reconstruction, its preparation method, and its applications. This invention utilizes cobalt-based perovskite PrBaCo2O 5+δ Using PBC material as a substrate, two transition metals, M1 (Zr, Hf, or Ti) and M2 (Nb, Mo, Ta, or V), are co-doped with Y in a specific ratio to partially replace Co at the B site, thus reconstructing a doped biphase oxygen electrode material in situ. The main phase is a defect-containing doped cobalt-based perovskite, and the second phase is a barium-based double perovskite containing Y, M1, and M2. This material exhibits a high coefficient of thermal expansion, closely matching the electrolyte BCZYYb, resulting in a battery with excellent electrochemical performance.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] The doped biphase oxygen electrode material based on in-situ reconstruction is a perovskite oxide with the chemical formula PrBaCo. 2-x-y-z M1 x Y z M2 y O 5+δ In the formula, M1 is any one of Zr, Hf, and Ti, M2 is any one of Nb, Mo, Ta, and V, 0.05≤x≤0.15, 0.05≤y≤0.15, 0.05≤z≤0.2, and δ represents non-stoichiometric oxygen vacancies.

[0007] Furthermore, the main phase of the doped dual-phase oxygen electrode material based on in-situ reconstruction is a defect-containing doped cobalt-based perovskite, and the second phase is a barium-based double perovskite containing Y, M1 and M2, wherein the proportion of the second phase is 6 to 12 wt%.

[0008] The oxygen electrode material PrBaCo in this invention 2-x-y-z M1 x Y z M2 y O 5+δ It has a perovskite structure and is composed of PrBaCo2O 5+δThe material is a substrate obtained by co-doping with transition metals M1 (Zr, Hf, or Ti), M2 (Nb, Mo, Ta, or V), and Y in a specific ratio to partially replace Co at the B site. The inventors discovered that co-doping with M1, M2, and Y can reconstruct a biphase oxygen electrode material in situ. This doped biphase oxygen electrode material exhibits a significantly reduced TEC, resulting in good interfacial contact with the electrolyte and improved battery durability. Simultaneously, co-doping with M1, M2, and Y enhances ORR and OER activities, as well as oxygen vacancy concentration, further improving the battery's electrochemical performance. The possible reasons are as follows: Firstly, M1 (Zr, Hf, or Ti) exhibits good chemical stability in H2O and / or CO2 atmospheres, and its introduction improves the chemical stability of the oxygen electrode material under operating conditions. Simultaneously, M2 (Nb, Mo, Ta, or V) are all high-valence (+5), thus possessing strong electron-withdrawing capabilities, which weakens the Co-O bond, releasing more oxygen vacancies. This, in turn, enhances ORR activity and surface exchange kinetics, and reduces the TEC of perovskite. Furthermore, Y, with its fixed oxidation state, can also increase the oxygen vacancy concentration, improving proton conduction, ORR activity, and phase stability. Secondly, high-valence M2 is more conducive to the segregation of a second phase. Since it is an in-situ reconstructed two-phase material, the contact between the main phase and the second phase is far better than that of mechanically mixed composite oxygen electrode materials. Simultaneously, the in-situ generated composite oxygen electrode material has good contact with the electrolyte interface. The formation of the second phase is beneficial to improving the chemical stability of the material; furthermore, during the formation of the second phase, the main phase generates more oxygen vacancy defects, which can further optimize and improve the overall oxygen vacancy concentration of the material, thereby improving its electrochemical performance. In summary, M1, M2, and Y work synergistically to partially replace Co at the B site with a specific ratio of co-doped components, thus reconstructing the doped dual-phase oxygen electrode material PrBaCo in situ. 2-x-y-z M1 x M2 y Y z O 5+δ The thermal expansion coefficient of this material is close to that of the electrolyte BCZYYb, resulting in good matching and the battery made from it exhibiting excellent electrochemical performance.

[0009] Preferably, M1 is Zr and M2 is Nb or Ta; more preferably, M1 is Zr and M2 is Nb.

[0010] Preferably, 0.1≤x≤0.15, 0.05≤y≤0.1, and 0.1≤z≤0.15.

[0011] In a preferred embodiment of the present invention, the chemical formula of the doped biphase oxygen electrode material based on in-situ reconstruction is PrBaCo. 1.7 Zr 0.1 Y 0.1 Nb 0.1 O 5+δ.

[0012] Secondly, the present invention provides a method for preparing the aforementioned doped biphase oxygen electrode material based on in-situ reconstruction, which is a sol-gel method, comprising the following steps:

[0013] (1) Press PrBaCo 2-x-y-z M1 x Y z M2 y O 5+δ The stoichiometric ratio of the chelating agent and metal salts containing Pr, Ba, Co, M1, M2, and Y was used to dissolve in water to form a mixed solution. The pH of the mixed solution was then adjusted to 7.5–8.5 using a pH adjuster, and the solution was heated and evaporated under stirring to obtain a gel. The molar ratio of the chelating agent to the total metal ions was (2–5):1, and the total metal ions consisted of Pr, Ba, Co, M1, M2, and Y ions.

[0014] (2) The gel was calcined and pulverized in air to obtain PrBaCo. 2-x-y-z M1 x Y z M2 y O 5+δ Powder, namely, doped two-phase oxygen electrode material based on in-situ reconstruction.

[0015] Further, in step (1), the chelating agent is at least one of oxalic acid, citric acid, and ethylenediaminetetraacetic acid; the metal salt is a metal nitrate, oxalate, or halide; and the pH adjuster is ammonia, sodium bicarbonate, or triethanolamine.

[0016] Further, in step (2), the calcination is carried out at 900-1100℃ for 2-5 hours, preferably 3-4 hours; the pulverization is carried out by air jet milling or ball milling until the particle size D50 is 300-600 mesh.

[0017] Thirdly, the present invention also provides the aforementioned doped dual-phase oxygen electrode material PrBaCo based on in-situ reconstruction. 2-x-y-z M1 x Y z M2 y O 5+δ Application in proton-conducting solid oxide fuel cells using H2 as fuel.

[0018] The present invention also provides the application of the aforementioned doped biphase oxygen electrode material based on in-situ reconstruction in proton-conductive solid oxide electrolyzers for electrolyzing H2O or co-electrolyzing H2O-CO2.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. This invention prepares a doped oxygen electrode material with a dual-phase structure by co-doping the Co at the B site with transition metals M1 (Zr, Hf or Ti), M2 (Nb, Mo, Ta or V) and Y in a specific ratio, wherein the second phase accounts for 6wt% to 12wt%. This oxygen electrode material has a low coefficient of thermal expansion and good compatibility with the electrolyte BCZYYb.

[0021] 2. The oxygen electrode material prepared by this invention has excellent electrochemical performance. When used in a proton-conducting solid oxide fuel cell, it achieves a high power density, and when used in a solid oxide electrolyzer, it achieves a high current density. At the same time, the oxygen electrode material has excellent long-term working stability, which solves the problem of significant performance degradation of cobalt-based oxygen electrode materials. Attached Figure Description

[0022] Figure 1 This is a homemade battery testing device.

[0023] Figure 2 The image shows the XRD pattern of the oxygen electrode material PBCZYN prepared in Example 1.

[0024] Figure 3 HR-TEM and mapping of the oxygen electrode material PBCZYN prepared in Example 1.

[0025] Figure 4 SEM image of the cross-section of the battery assembled with the oxygen electrode material prepared in Example 1 after stability testing.

[0026] Figure 5 The thermal expansion coefficient-temperature curve of the oxygen electrode material PBCZYN prepared in Example 1 within the range of 350℃ to 850℃.

[0027] Figure 6 The voltage and peak power density of the battery assembled with the oxygen electrode material prepared in Example 1 are shown as the changes in current density at 600°C, 650°C, 700°C and 750°C when H2 is used as fuel.

[0028] Figure 7 The graph shows a comparison of the peak power density of batteries assembled with the oxygen electrode materials prepared in Example 1 and Comparative Example 1 at different temperatures.

[0029] Figure 8 The current density versus voltage curves of the battery assembled with the oxygen electrode material prepared in Example 1 during H2O electrolysis at 600℃, 650℃, 700℃ and 750℃.

[0030] Figure 9 The graph shows a comparison of the current density of batteries assembled with the oxygen electrode materials prepared in Example 1 and Comparative Example 1 during the electrolysis of H2O at different temperatures.

[0031] Figure 10 The voltage versus current density curves of the battery assembled with the oxygen electrode material prepared in Example 1 during co-electrolysis of CO2-H2O at 600℃, 650℃, 700℃ and 750℃.

[0032] Figure 11 The voltage-time curves of the batteries assembled with the oxygen electrode materials prepared in Example 1 and Comparative Example 1 when used as fuel cells.

[0033] Figure 12 The voltage-time curves of the batteries assembled with the oxygen electrode materials prepared in Example 1 and Comparative Example 1 when used as electrolytic cells. Detailed Implementation

[0034] The present invention will be further described below with reference to specific embodiments, but the present invention is not limited to the following embodiments.

[0035] Unless otherwise specified, the experimental methods described in the following examples are conventional methods; the reagents and materials described are commercially available unless otherwise specified.

[0036] Example 1---Preparation of doped dual-phase oxygen electrode material PrBaCo 1.7 Zr 0.1 Y 0.1 Nb 0.1 O 5+δ

[0037] M1 is Zr, x = 0.1, M2 is Nb, y = 0.1, z = 0.1.

[0038] (1) According to the chemical formula PrBaCo 1.7 Zr 0.1 Y 0.1 Nb 0.1 O 5+δ The stoichiometric ratios of praseodymium nitrate (Pr(NO3)3·6H2O), barium nitrate (Ba(NO3)2), cobalt nitrate (Co(NO3)2·6H2O), zirconium nitrate (Zr(NO3)2·4H2O), yttrium nitrate (Y(NO3)3·6H2O), and niobium oxalate hydrate (C 10 H5NbO 20 Citric acid and ethylenediaminetetraacetic acid (EDTA) were dissolved in deionized water to form a solution. Then, citric acid and EDTA were weighed out in a molar ratio of 2.5:1:1 and dissolved in the above solution to form a mixed solution. The pH of the above solution was then adjusted to 8.0±0.1 using ammonia (NH3·H2O), and the solution was heated and evaporated with stirring to obtain a gel.

[0039] (2) The gel obtained in step (1) was placed in a muffle furnace and calcined at 950°C for 4 hours in an air atmosphere at a rate of 10°C / min. After calcination, it was naturally cooled to room temperature. The calcined material was then removed and air-jet pulverized to 400-500 mesh to obtain the doped biphase oxygen electrode material PrBaCo based on in-situ reconstruction. 1.7 Zr 0.1 Y 0.1 Nb 0.1 O 5+δ (PBCZYN).

[0040] Example 2---Preparation of doped dual-phase oxygen electrode material PrBaCo 1.85 Zr 0.05 Y 0.05 Nb 0.05 O 5+δ

[0041] The rest is the same as in Example 1, except that the ratios of M1, M2, and Y are different: x = 0.05, y = 0.05, z = 0.05; correspondingly according to PrBaCo 1.85 Zr 0.05 Y 0.05 Nb 0.05 O 5+δ The ingredients are prepared according to the corresponding stoichiometric ratios of each element.

[0042] Example 3---Preparation of doped dual-phase oxygen electrode material PrBaCo 1.75 Zr 0.1 Y 0.1 Nb 0.05 O 5+δ

[0043] The rest is the same as in Example 1, except that the ratios of M1, M2, and Y are different: x = 0.1, y = 0.05, z = 0.1; correspondingly according to PrBaCo 1.75 Zr 0.1 Y 0.1 Nb 0.05 O 5+δ The ingredients are prepared according to the corresponding stoichiometric ratios of each element.

[0044] Example 4---Preparation of doped dual-phase oxygen electrode material PrBaCo 1.6 Zr 0.15 Y 0.15 Nb 0.1 O 5+δ

[0045] The rest is the same as in Example 1, except that the ratios of M1, M2, and Y are different: x = 0.15, y = 0.1, z = 0.15; correspondingly according to PrBaCo 1.6 Zr0.15 Y 0.15 Nb 0.1 O 5+δ The ingredients are prepared according to the corresponding stoichiometric ratios of each element.

[0046] Example 5---Preparation of doped dual-phase oxygen electrode material PrBaCo 1.5 Zr 0.15 Y 0.2 Nb 0.15 O 5+δ

[0047] The rest is the same as in Example 1, except that the ratios of M1, M2, and Y are different: x = 0.15, y = 0.15, z = 0.2; correspondingly according to PrBaCo 1.5 Zr 0.15 Y 0.2 Nb 0.15 O 5+δ The ingredients are prepared according to the corresponding stoichiometric ratios of each element.

[0048] Example 6---Preparation of doped dual-phase oxygen electrode material PrBaCo 1.7 Zr 0.1 Y 0.1 Ta 0.1 O 5+δ

[0049] The rest is the same as in Example 1, except that the type of M2 is different; M2 is Ta; and correspondingly, it is calculated according to PrBaCo. 1.7 Zr 0.1 Y 0.1 Ta 0.1 O 5+δ The ingredients are prepared according to the corresponding stoichiometric ratios of each element.

[0050] Example 7---Preparation of doped dual-phase oxygen electrode material PrBaCo 1.7 Hf 0.1 Y 0.1 Mo 0.1 O 5+δ

[0051] The rest is the same as in Example 1, except that M1 and M2 are of different types: M1 is Hf and M2 is Mo; correspondingly, according to PrBaCo... 1.7 Hf 0.1 Y 0.1 Mo 0.1 O 5+δ The ingredients are prepared according to the corresponding stoichiometric ratios of each element.

[0052] Example 8---Preparation of doped dual-phase oxygen electrode material PrBaCo 1.7 Ti 0.1 Y0.1 V 0.1 O 5+δ

[0053] The rest is the same as in Example 1, except that M1 and M2 are of different types: M1 is Ti and M2 is V; correspondingly, according to PrBaCo... 1.7 Ti 0.1 Y 0.1 V 0.1 O 5+δ The ingredients are prepared according to the corresponding stoichiometric ratios of each element.

[0054] Comparative Example 1---Preparation of Doped Dual-Phase Oxygen Electrode Material PrBaCo 1.8 Zr 0.1 Y 0.1 O 5+δ

[0055] The rest is the same as in Example 1, except that: there is no Nb, that is, only Zr and Y are doped; correspondingly, according to the chemical formula PrBaCo 1.8 Zr 0.1 Y 0.1 O 5+δ The ingredients are prepared according to the stoichiometric ratio of each element.

[0056] Comparative Example 2---Preparation of Doped Dual-Phase Oxygen Electrode Material PrBaCo 1.8 Y 0.1 Nb 0.1 O 5+δ

[0057] The rest is the same as in Example 1, except that: no Zr is used, i.e., only Nb and Y are doped; correspondingly, according to the chemical formula PrBaCo... 1.8 Y 0.1 Nb 0.1 O 5+δ The ingredients are prepared according to the stoichiometric ratio of each element.

[0058] Comparative Example 3---Preparation of Doped Dual-Phase Oxygen Electrode Material PrBaCo 1.7 Zr 0.1 Y 0.1 Zn 0.1 O 5+δ

[0059] The rest is the same as in Example 1, except that the type of M2 is different; M2 is Zn; correspondingly, according to the chemical formula PrBaCo... 1.7 Zr 0.1 Y 0.1 Zn 0.1 O 5+δ The ingredients are prepared according to the stoichiometric ratio of each element.

[0060] Application examples

[0061] The doped biphase oxygen electrode materials prepared in the above embodiments and comparative examples were used in R-PCCs, with the doped biphase oxygen electrode material PrBaCo prepared in Example 1 being an example. 1.7 Zr 0.1 Y 0.1 Nb 0.1 O 5+δ For example, the assembly process of a single cell is as follows:

[0062] (S1) will be composed of 57wt% NiO and 30wt% BaCe 0.7 Zr 0.1 Y 0.1 Yb 0.1 O 3-δ The powder consisting of (BCZYYb) and 13wt% starch was mixed and ball-milled in ethanol for 24 hours, then dried and uniaxially pressed into a sheet with a diameter of 15 mm, and then fired at 1100°C for 2 hours to form a green porous hydrogen electrode substrate.

[0063] (S2) 1 wt% NiO as a sintering aid is mixed with BCZYYb powder and fully dispersed in an organic dispersant (5 wt% ethyl cellulose, 20 wt% terpineol, 71 wt% isopropanol, 2 wt% triethanolamine, 2 wt% polyethylene glycol 400) to form a stable suspension. Then, it is dropped into the center of the hydrogen electrode substrate prepared in step (S1) and immediately rotated at 2500 rpm for 30 seconds to form a thin and uniform electrolyte BCZYYb layer (the thickness of the electrolyte layer is controlled by the rotation speed and number of cycles of the spin coater). After that, it is dried at room temperature to remove the solvent in the BCZYYb layer, and a hydrogen electrode-electrolyte bilayer structure is obtained.

[0064] (S3) Then the hydrogen electrode-electrolyte bilayer structure obtained in step (S2) is placed in a muffle furnace and sintered at 1450°C for 5 hours to obtain a dense BCZYYb electrolyte, thereby preparing a half cell.

[0065] (S4) The oxygen electrode material PrBaCo prepared in Example 1 1.7 Zr 0.1 Y 0.1 Nb 0.1 O 5+δ The oxygen electrode material slurry is obtained by adding organic solvent (terpineol: ethyl cellulose = 96:4) to a mortar at a mass ratio of 1:1.5 and grinding for 1 hour. The oxygen electrode material slurry is then coated onto the electrolyte surface sintered in step (S3) by screen printing. After drying, it is calcined at 950°C for 2 hours, thus completing the manufacturing of the entire single cell.

[0066] Using a homemade testing device ( Figure 1 The single cell prepared above was tested (as shown). Specifically, the single cell was sealed on an alumina tube using conductive silver paste, and Ag wires fixed with conductive silver paste were used as connecting wires for the hydrogen and oxygen electrodes. To evaluate the performance of the fuel cell using H2 as fuel and the performance of the electrolyzer for H2O electrolysis and co-electrolysis of CO2-H2O, approximately 3% water vapor by volume was generated at room temperature using a water bubbler before introducing the fuel into the cell. The gas flow rate was set to 30 ml / min. The power output performance and electrolysis of the cell were tested using the Thales cell test system. AC impedance spectroscopy was performed using a Zennium electrochemical workstation in the frequency range of 0.01-1 MHz under a 10 mV AC perturbation.

[0067] Other embodiments and comparative examples assemble single cells according to the above method, the difference being that the oxygen electrode material in step (S4) is replaced.

[0068] Testing and Analysis

[0069] The above embodiments, comparative examples, application examples, and comparative application examples were tested and characterized, and the results and analysis are as follows.

[0070] 1. Structural performance

[0071] The oxygen electrode material PrBaCo prepared in Example 1 1.7 Zr 0.1 Y 0.1 Nb 0.1 O 5+δ The XRD pattern of (PBCZYN) is shown in Figure 2, and its HR-TEM and mapping plots are shown in Figure 3. Figure 3 As shown. The cross-sectional SEM image of the battery assembled using the oxygen electrode material prepared in Example 1 after stability testing is shown below. Figure 4 As shown.

[0072] from Figure 2 As can be seen from the data, the diffraction peaks of the oxygen electrode material PBCZYN prepared in Example 1 are all similar to those of PrBaCo2O. 5+δ The main diffraction peaks represented by the PDF standard card (PDF No.: 00-053-0131) of (PBC) confirm that Zr, Y, and Nb were simultaneously doped into the B-sites of the perovskite material, and the doped PBCZYN retained its perovskite structure without damage. Meanwhile, compared to PBC, the main diffraction peaks of PBCZYN prepared in Example 1 shifted towards smaller angles, indicating that Zr, Y, and Nb were successfully doped into the material's crystal lattice. Figure 3 As shown in (a) and 3(b), the lattice spacing is 0.197 nm, corresponding to the (200) crystal plane of PBCZYN. Similarly, Figure 3(c) and 3(d) verified that the lattice spacing of the (220) crystal plane of Ba2(Zr) is 0.285 nm. 1 / 3 Y 1 / 3 Nb 1 / 3 )2O6 secondary phase. For example Figure 3 As shown in the TEM and mapping images in Figure e, Ba, Zr, Y, and Nb are abundant in the regions marked by the white dashed circles, with Zr, Y, and Nb having approximately equal abundances, while Pr and Co are almost absent. The HR-TEM and mapping spectra of PBCZYN oxide, along with XRD results, collectively confirm the presence of Ba2(Zr) in the PBCZYN oxide. 1 / 3 Y 1 / 3 Nb 1 / 3 The formation of the second phase of )2O6.

[0073] In conclusion, combining Figure 2 and Figure 3 It can be seen that the oxygen electrode material PBCZYN prepared in Example 1 has a two-phase structure, with the main phase being a defect-doped cobalt-based perovskite, namely PrBa. 1-u Co 1.7 Zr 0.1-u Y 0.1-u Nb 0.1-u O 5+δ The second phase is a barium-based double perovskite containing Y, M1, and M2, namely Ba2(Y 1 / 3 Zr 1 / 3 Nb 1 / 3 )2O6. By performing Rietveld refinement fitting on the XRD pattern, the area of ​​the diffraction peaks can be calculated to determine the proportion of the second phase. After refinement fitting, the proportion of the second phase in the oxygen electrode material prepared in Example 1 is calculated to be 11.2 wt%. Similarly, the oxygen electrode materials prepared in the other embodiments of the present invention also show a two-phase structure according to the XRD patterns. The specific data of the proportion of the second phase after refinement fitting and calculation are shown in Table 1, that is, the proportion of the second phase is 6 wt% to 12 wt%.

[0074] from Figure 4 As can be seen, the oxygen electrode surface in the battery still exhibits a loose and porous morphology after electrochemical performance and stability tests, and the material has not agglomerated; moreover, the interface between the oxygen electrode, electrolyte, and hydrogen electrode remains in good contact.

[0075] In summary, the oxygen electrode material prepared in the embodiments of the present invention still retains the perovskite structure and has a two-phase structure, wherein the main phase is a defect-doped cobalt-based perovskite, and the second phase is a barium-based double perovskite containing Y, M1, and M2, accounting for 6wt% to 12wt%. In proton-conducting reversible solid oxide batteries assembled with the oxygen electrode material prepared by the present invention, the interfaces between the oxygen electrode, electrolyte, and hydrogen electrode remain in good contact.

[0076] 2. Coefficient of thermal expansion (TEC) test

[0077] The coefficient of thermal expansion of the oxygen electrode materials prepared in each embodiment and comparative example was tested using a thermal expansion meter. The specific method was as follows: the material powder was pressed into a strip shape of 1m × 6mm × 10mm. The test temperature range was 350–850℃, the heating rate was 5℃ / min, and the sample length was recorded every 50℃. The thermal expansion rate at the corresponding temperature was calculated using the following formula (1) in conjunction with the temperature change. Then, a thermal expansion rate-temperature curve was plotted with the thermal expansion rate as the ordinate and temperature as the abscissa. The thermal expansion rate-temperature curve of the oxygen electrode material PBCZYN prepared in Example 1 within the range of 350℃–850℃ is shown below. Figure 5 As shown. By linearly fitting the thermal expansion coefficient-temperature curve, the slope of the fitted curve is the thermal expansion coefficient of the oxygen electrode material in the range of 350℃ to 850℃.

[0078] The coefficient of thermal expansion α = (L - L0) / L0(1)

[0079] In the formula, L is the length of the sample at temperature T, and L0 is the length of the sample at 350℃. The test results of the thermal expansion coefficient of the oxygen electrode materials prepared in each embodiment and comparative example are shown in Table 1.

[0080] Table 1. Proportion of the second phase and coefficient of thermal expansion of oxygen electrode materials

[0081]

[0082] As can be seen from Table 1, compared with the blank example, the substrate material PrBaCo2O 5+δ The coefficient of thermal expansion is 27.56 × 10⁻⁶. -6 K -1 In comparison, the oxygen electrode materials prepared in the embodiments of the present invention have significantly lower coefficients of thermal expansion, approximately 16.0 × 10⁻⁶. -6 K -1 ~18.5×10 -6 K -1 In particular, the coefficient of thermal expansion in preferred embodiment 1 is less than 17.0 × 10⁻⁶. -6 K -1 The coefficient of thermal expansion of the electrolyte BCZYYb is 12.0 × 10⁻⁶. -6 K -1 The closer the coefficient of thermal expansion of the oxygen electrode material is to that of the electrolyte, the better the contact between the oxygen electrode material and the electrolyte interface will be. This will reduce the polarization resistance of the battery. The reduction in polarization resistance can help improve the peak power density when the battery is used as a fuel cell and the current density when it is used as an electrolyzer.

[0083] 3. Electrochemical performance testing

[0084] a) Peak power density when used as a solid oxide fuel cell

[0085] The battery assembled with the oxygen electrode material prepared in Example 1, using H2 as fuel (hydrogen electrode feed: 97% H2 + 3% H2O; oxygen electrode feed: air), shows the voltage and peak power density as a function of current density at 600°C, 650°C, 700°C, and 750°C as follows: Figure 6 As shown in the figure; a comparison of the peak power density of the two batteries assembled with the oxygen electrode materials prepared in Example 1 and Comparative Example 1 at different temperatures is shown in the figure. Figure 7 .from Figure 6 and Figure 7 As can be seen, compared with the battery assembled with the oxygen electrode material prepared in Comparative Example 1, the battery assembled with the oxygen electrode material prepared in Example 1 has a significantly higher power density at all temperatures when used as a fuel cell with H2 as fuel. Table 2 shows the specific data for the peak power density of the batteries assembled with the oxygen electrode materials prepared in each example and the comparative example at 700°C with H2 as fuel.

[0086] b) Current density when used as a solid oxide electrolytic cell:

[0087] The current density versus voltage curves of the battery assembled with the oxygen electrode material prepared in Example 1 at 600℃, 650℃, 700℃, and 750℃ during H2O electrolysis (hydrogen electrode feed: 97% H2 + 3% H2O; oxygen electrode feed: 3% H2O + 97% argon) are shown below. Figure 8 As shown in the figure; a comparison of the current density of the two batteries assembled with the oxygen electrode materials prepared in Example 1 and Comparative Example 1 during the electrolysis of H2O at different temperatures is shown in the figure. Figure 9 As shown. From Figure 8 and Figure 9 It can be concluded that, compared with the battery assembled with the oxygen electrode material prepared in Comparative Example 1, the battery assembled with the oxygen electrode material prepared in Example 1 exhibits higher current density when electrolyzing H2O at various temperatures, i.e., when used as an electrolytic cell for H2O electrolysis. Specific data on the current density of the batteries assembled with the oxygen electrode materials prepared in each example and the comparative example when electrolyzing H2O at 700°C are shown in Table 2.

[0088] The current density versus voltage curves of the battery assembled with the oxygen electrode material prepared in Example 1 during co-electrolysis of CO2-H2O at 600℃, 650℃, 700℃, and 750℃ are shown below. Figure 10 As shown. From Figure 10 It can be concluded that the battery assembled with the oxygen electrode material prepared in Example 1 also exhibits a high current density when electrolyzing co-CO2-H2O at various temperatures, i.e., when used as an electrolytic cell for co-electrolyzing CO2-H2O. Meanwhile, from... Figure 10 It can also be seen that CO2-H2O co-electrolysis exhibits higher current density at higher temperatures (750℃ and 700℃); as the test temperature decreases, the current density of CO2-H2O co-electrolysis decreases, which is due to the slower CO2 reaction kinetics caused by the lower temperature. Specific data on the current density of batteries assembled with the oxygen electrode materials prepared in each embodiment and comparative example during CO2-H2O co-electrolysis at 700℃ are shown in Table 2.

[0089] Table 2 Electrochemical Performance Tests

[0090]

[0091] from Figure 6-10 As can be seen from the data in Table 2, the battery assembled with the oxygen electrode material prepared in the embodiments of the present invention has a high peak power density when used as a fuel cell, and has a high current density when used as an electrolyzer for both electrolysis of H2O and co-electrolysis of CO2-H2O.

[0092] c) Stability testing:

[0093] The voltage-time curve of the battery assembled with the oxygen electrode material prepared in Example 1 and Comparative Example 1 (using H2 as fuel) at 650°C is shown below. Figure 11 As shown; the voltage-time curves of the batteries assembled with the oxygen electrode materials prepared in Example 1 and Comparative Example 1 when used as electrolytic cells for electrolyzing H2O at 650°C are shown in the figure. Figure 12 As shown. From Figure 11 and Figure 12 As can be seen, the battery assembled with the oxygen electrode material prepared in Example 1 exhibits excellent stability, and can operate stably in constant potential mode for about 150 hours when used as a fuel cell and an electrolyzer, demonstrating good stability. In contrast, the battery assembled with the oxygen electrode material prepared in Comparative Example 1 can only operate for about 80 hours.

[0094] In summary, the doped biphase oxygen electrode material based on in-situ reconstruction prepared by this invention has a low coefficient of thermal expansion and good matching with the electrolyte BCZYYb; when used in a solid oxide fuel cell, the cell has a high power density; when used in a solid oxide electrolyzer, the electrolyzer has a high current density; and the oxygen electrode has excellent long-term working stability.

Claims

1. A doped dual-phase oxygen electrode material based on in-situ reconstruction, which is a perovskite oxide, characterized in that, The chemical formula is PrBaCo 2-x-y-z M1 x Y z M2 y O 5+δ In the formula, M1 is any one of Zr, Hf, and Ti, M2 is any one of Nb, Mo, Ta, and V, 0.05≤x≤0.15, 0.05≤y≤0.15, 0.05≤z≤0.2, and δ represents non-stoichiometric oxygen vacancies.

2. The doped dual-phase oxygen electrode material based on in-situ reconstruction according to claim 1, characterized in that, The main phase of the doped dual-phase oxygen electrode material based on in-situ reconstruction is a defect-containing doped cobalt-based perovskite, and the second phase is a barium-based double perovskite containing Y, M1 and M2, wherein the proportion of the second phase is 6 to 12 wt%.

3. The doped dual-phase oxygen electrode material based on in-situ reconstruction according to claim 1, characterized in that, M1 is Zr, and M2 is Nb or Ta; preferably, M1 is Zr and M2 is Nb.

4. The doped dual-phase oxygen electrode material based on in-situ reconstruction according to claim 1, characterized in that, 0.1≤x≤0.15, 0.05≤y≤0.1, 0.1≤z≤0.

15.

5. The doped dual-phase oxygen electrode material based on in-situ reconstruction according to claim 1, characterized in that, The chemical formula of the doped biphase oxygen electrode material based on in-situ reconstruction is PrBaCo. 1.7 Zr 0.1 Y 0.1 Nb 0.1 O 5+δ .

6. The method for preparing the doped dual-phase oxygen electrode material based on in-situ reconstruction according to any one of claims 1-5, characterized in that, The sol-gel method includes the following steps: (1) Press PrBaCo 2-x-y-z M1 x Y z M2 y O 5+δ The stoichiometric ratio of the chelating agent and metal salts containing Pr, Ba, Co, M1, M2, and Y was used to dissolve in water to form a mixed solution. The pH of the mixed solution was then adjusted to 7.5–8.5 using a pH adjuster, and the solution was heated and evaporated under stirring to obtain a gel. The molar ratio of the chelating agent to the total metal ions was (2–5):1, and the total metal ions consisted of Pr, Ba, Co, M1, M2, and Y ions. (2) The gel was calcined and pulverized in air to obtain PrBaCo. 2-x-y-z M1 x Y z M2 y O 5+δ Powder, namely, doped two-phase oxygen electrode material based on in-situ reconstruction.

7. The preparation method according to claim 6, characterized in that, In step (1), the chelating agent is at least one of oxalic acid, citric acid, and ethylenediaminetetraacetic acid; the metal salt is a metal nitrate, oxalate, or halide; and the pH adjuster is ammonia, sodium bicarbonate, or triethanolamine.

8. The preparation method according to claim 6, characterized in that, In step (2), the calcination is carried out at 900-1100℃ for 2-5 hours; the pulverization is carried out by air jet milling or ball milling until the particle size D50 is 300-600 mesh.

9. The application of the in-situ reconstructed doped biphase oxygen electrode material according to any one of claims 1-5 in a proton-conducting solid oxide fuel cell using H2 as fuel.

10. The application of the in-situ reconstructed doped biphase oxygen electrode material according to any one of claims 1-5 in a proton-conducting solid oxide electrolyzer for electrolyzing H2O or co-electrolyzing H2O-CO2.

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