A fluorite structure catalyst for modifying an oxygen electrode of a reversible proton ceramic battery and a preparation method thereof

Abstract

The application belongs to the technical field of reversible proton ceramic electrochemical cells, and discloses a fluorite structure catalyst for modifying an oxygen electrode of a reversible proton ceramic cell and a preparation method thereof. x Ce 1‑x O 2+δ , 0 5+δ x≤0.2; the oxygen electrode of the application is PrBaCo2O . The application also discloses a preparation method of the catalyst. The catalyst of the application can modify the surface morphology of the oxygen electrode, effectively inhibit the lattice size change caused by Ba segregation and Co valence change on the surface of the oxygen electrode in a long-term medium-temperature and high-humidity environment, and improve the surface ion exchange coefficient and diffusion coefficient performance of the oxygen electrode, thereby improving the electrochemical activity. The catalyst material of the application can make the electrochemical cell based on the oxygen electrode have excellent long-term stability and high power density / current density.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of reversible proton ceramic electrochemical cells (R-PCEC for short), and particularly relates to a fluorite-structure oxide Pr 5+δ (abbreviated as PBC) oxygen electrode surface modified double perovskite PrBaCo2O x Ce 1-x O 2+δ (abbreviated as PCO) catalyst and a preparation method thereof. BACKGROUND

[0002] With the increasing demand for low-carbon emission reduction, green hydrogen production technology has attracted widespread attention. Compared with the traditional reforming and cracking hydrogen production method, electrocatalytic water splitting for hydrogen production can obtain high-purity hydrogen product and largely avoid environmental pollution, achieving zero carbon emission. Among all the water electrolysis hydrogen production technologies, solid oxide fuel cells (SOFC) have the advantages of high conversion efficiency and power density, fuel diversity, full solid state, modular assembly, zero pollution, etc. The product hydrogen of the reversible proton ceramic electrochemical cell (R-PCEC) in the electrolysis cell mode (EL mode) is generated at the fuel electrode side, without the need for additional hydrogen purification and the problem of nickel-based fuel electrode oxidation, becoming one of the most promising methods for water electrolysis hydrogen production. However, the durability problem of the oxygen electrode seriously hinders the practicalization process. The oxygen reduction reaction (ORR) under the fuel cell mode (FC) and the oxygen evolution reaction (OER) under the electrolysis mode (EL) are slow and complex at low temperatures. The polarization resistance of the oxygen electrode still dominates the energy loss of the entire R-PCEC process. Therefore, in order to reduce the energy loss of the R-PCEC, there is an urgent need for a high-efficiency and durable oxygen electrode.

[0003] The surface morphology and modification of oxygen electrode is one of the main factors to effectively affect the activity and stability of oxygen reduction reaction (ORR) in fuel cell mode (FC) and oxygen evolution reaction (OER) in electrolysis cell mode (EL). Among them, the oxygen electrode catalyst is one of the most effective and direct means to modify the surface morphology of the oxygen electrode. At present, there are many methods to prepare oxygen electrode catalysts, and the ratio of different elements and solvents will affect the microstructure of the product, such as catalyst morphology, size and surface area, etc., so the electrochemical activity and stability of the modified oxygen electrode will also be affected. Compared with pulse laser deposition (PLD), chemical vapor deposition (CVD) and magnetron sputtering, etc. The solvent impregnation method has the advantages of simple preparation, controllable element ratio, uniform distribution of catalysts, etc. The fluorite phase catalyst has a CaF2 type fluorite structure, i.e. a symmetrical cubic structure, which can produce more oxygen vacancies due to its redox characteristics and high instability of lattice oxygen. The surface catalytic material with fluorite structure also has active ORR / OER catalytic activity. Therefore, appropriate doping of other metal oxides for synergistic effect will improve the catalytic activity and long-term stability of the catalyst.

[0004] Document (“An Efficient Steam-Induced Heterostructured Air Electrode for Protonic Ceramic ElectroChemical Cells” K. Xu, H. Zhang, Y. Xu, F. He, Y. Zhou, Y. Pan, J. Ma, B. Zhao, W. Yuan, Y. Chen, M. Liu, Advanced Functional Materials 2022, DOI: https: / / doi.org / 10.1002 / adfm.2021109982110998) (referred to as background art) discloses a method for preparing a surface catalyst of an oxygen electrode, which enhances the catalytic activity and performance stability of a perovskite-type oxygen electrode PrBaCo 1.6 Fe 0.2 Nb 0.2 O 5+δ (PBCFN) through a water-promoted surface restructuring process. Under specific conditions, a PBCFN electrode framework rich in Nb and a surface covered with PBCFN nanoparticles lacking Nb were prepared. The results show that the surface Nb-deficient phase can improve the electrochemical activity and durability of the oxygen electrode. The highest power density of the single cell Ni-BZCYYb||BZCYYb||PBCFN at 700, 650 and 600 °C is: 1.45, 1.06 and 0.72 W cm -2When the humidified air is introduced on the oxygen electrode side, the electrochemical cell is operated in electrolysis mode, and the current density at 1.3 V voltage condition is 3.84, 2.15 and 1.04 A cm at 700, 650 and 600 ℃, respectively -2 The technology improves the performance of the proton ceramic fuel cell.

[0005] However, the surface restructuring catalyst has the following shortcomings and deficiencies:

[0006] ① The PBCFN catalyst is generated by the segregation of the PBCFN oxygen electrode in a high-temperature and high-humidity environment, and the main element composition is still the PBCFN perovskite material, but the content of Nb is reduced, and the performance improvement beyond the element characteristics of the PBCFN oxygen electrode cannot be obtained. It is obviously weaker than the performance of the heterogeneous element catalyst.

[0007] ② The PBCFN surface restructuring catalyst must be generated under the induction of high-temperature water, and cannot generate effective PBCFN catalyst particles under initial conditions. The particle size cannot be formed below 400 ℃, and most of the PBCFN catalyst particles below 600 ℃ exist in the form of 100 nm in diameter, and do not have effective catalytic activity. In addition, when the temperature rises to 600 ℃, the PBCFN catalyst particle density per unit area needs to be continuously induced by water (more than 10 hours) to reach a stable and effective value (more than 25 square microns), which consumes time and energy.

[0008] ③ Due to the characteristics of the PBCFN perovskite and water induction, the surface restructuring catalyst has a granular morphology, cannot fully cover the surface of the oxygen electrode, and the particle size can only be slowly adjusted by factors such as actual working temperature, water vapor content and working time.

[0009] ④ The experimental results prove that after the PBCFN surface restructuring catalyst is induced by water for 10 hours at a working temperature of 600 ℃, the catalyst particle diameter and density reach the peak value, and the morphology cannot be further optimized and changed, and the catalyst content per unit area cannot be flexibly changed, thereby limiting the further improvement of the performance.

[0010] ⑤ The maximum power density of the single cell at 600 ℃ and the current density under the condition of 1.3 V voltage still needs to be improved. SUMMARY

[0011] In order to overcome the shortcomings and deficiencies of the prior art, the purpose of the present application is to provide a fluorite structure catalyst for modifying the oxygen electrode of a reversible proton ceramic cell and a preparation method thereof. The fluorite structure Pr x Ce 1-x O 2+δ (simplified as: PCO) catalyst is prepared by surface modification of the double perovskite PrBaCo2O5+δ The application is characterized in that: the PrBC is used to modify the fluorite structure catalyst of the oxygen electrode of the reversible proton ceramic battery, so that the oxygen electrode of the PrBC has higher electrochemical activity, and the surface element segregation and valence state change of the PrBC are inhibited in a high-humidity environment at a medium temperature of 650 DEG C, so that the excellent performance and stability of the PrBC are maintained.

[0012] The object of the application is achieved by the following technical solutions.

[0013] A fluorite structure catalyst for modifying an oxygen electrode of a reversible proton ceramic battery, which is composed of Pr x Ce 1-x O 2+δ , 0 < x < 0.2, preferably 0.09-0.2, and more preferably 0.1.

[0014] A preparation method of the fluorite structure catalyst for modifying the oxygen electrode of the reversible proton ceramic battery, comprising the following steps: uniformly mixing praseodymium nitrate Pr(NO3)3·6H2O, cerium nitrate Ce(NO3)3·6H2O, glycine, polyvinylpyrrolidone PVP and water to obtain a mixed solution; impregnating the mixed solution on a double-perovskite oxygen electrode framework, drying, repeating the impregnation and drying, and then calcining at 800-1000 DEG C for 1-2 h to obtain the fluorite structure catalyst for modifying the oxygen electrode of the reversible proton ceramic battery.

[0015] The mass ratio of the praseodymium nitrate, the cerium nitrate, the glycine and the polyvinylpyrrolidone is 1: (3-9): (0.6-1.8): (0.2-0.6).

[0016] The water is added in an amount that satisfies the concentration of the praseodymium nitrate and the cerium nitrate in the mixed solution of 0.05-0.3 mol / L.

[0017] The uniform mixing refers to mixing the substances by ball milling or stirring or homogenization or the like until the solvent is clear and free of precipitates.

[0018] The impregnation of the mixed solution on the double-perovskite oxygen electrode framework refers to drop-coating the mixed solution on the double-perovskite oxygen electrode framework; the amount of the mixed solution added at a time is 5-10 μL / 0.2826 cm 2 .

[0019] The drying temperature is 60-80 DEG C.

[0020] The heating rate of the calcination is 1-4 DEG C / min.

[0021] The double-perovskite oxygen electrode is a PBC oxygen electrode (PrBaCo2O 5+δ ).

[0022] The loading amount of PCO catalyst on the PBC oxygen electrode framework is 5-30 mg / cm 2 .

[0023] The glycine and polyvinylpyrrolidone can be replaced by octylphenyl polyoxyethylene ether; (increase the amount of catalyst attached per unit area), wherein the use concentration of octylphenyl polyoxyethylene ether is 0.5-2.0 vol.%, that is, 50-200 mL of octylphenyl polyoxyethylene ether per mole of PCO catalyst nitrate catalyst; the water is replaced by alcohol solvents such as anhydrous ethanol instead of deionized water, and the other components are still octylphenyl polyoxyethylene ether, or glycine and polyvinylpyrrolidone, which changes the surface tension of the catalyst solution, thereby changing the morphology of the catalyst (particles or films).

[0024] The preparation method of the PBC oxygen electrode material framework comprises the following steps:

[0025] (1) The PBC oxygen electrode material is prepared by sol-gel method: Pr(NO3)3·6H2O, Ba(NO3)2, Co(NO3)2·6H2O are sequentially dissolved in water according to the stoichiometric ratio, glycine and citric acid monohydrate are added to obtain a mixed solution; then the mixed solution is heated to 70-100 ℃ and continuously stirred until the solution is a deep red gel, then the gel is dried at 160-300 ℃ for 1-2 hours to ensure that the entire nitrate completes the explosion process; after taking out the precursor, it is moved to a muffle furnace and heated to 900-1100 ℃ at a heating rate of 1-4 ℃ / min, and then heated at constant temperature for 1-2 hours to obtain PBC oxygen electrode powder; wherein the molar ratio of total metal ions of praseodymium, barium and cobalt: glycine: citric acid monohydrate is 1:0.6-1.2:0.6-1.2;

[0026] (2) 1 g of PBC oxygen electrode powder, 0.76-1.14 g of terpineol, and 0.04-0.08 g of ethyl cellulose are weighed and mixed to obtain an oxygen electrode slurry; the oxygen electrode slurry is uniformly coated on the fuel electrode supported half-cell by screen printing method, dried and then placed in a muffle furnace and calcined at 800-1000 ℃ for 1-2 h to obtain a PBC oxygen electrode material framework.

[0027] The structure of the above-mentioned fuel electrode supported half-cell is oxygen electrode / / electrolyte / / fuel electrode, that is, it includes an electrolyte, and the two sides of the electrolyte are oxygen electrode and fuel electrode respectively.

[0028] The electrolyte is BaZr 0.1 Ce 0.7 Y 0.1 Yb 0.1 O 3-δ (BZCYYb1711).

[0029] The fuel electrode material adopts a composite fuel electrode composed of NiO and BZCYYb1711 electrolyte.

[0030] The fuel electrode supported proton conductor half-cell is prepared by co-casting.

[0031] A method for characterizing a reversible proton ceramic electrochemical cell stability test, comprising the following steps:

[0032] The oxygen electrode material is coated on the fuel electrode supported proton conductor single cell, humidified hydrogen (3 vol.%) is introduced on the fuel electrode side, and humidified air (3 vol.%) is introduced on the oxygen electrode side. The single cell is subjected to reversible electrochemical test, i.e. ±0.5 A cm -2 of current is applied, and the electrochemical cell is alternately operated in FC and EL modes for 2 hours, and the oxygen electrode stability is investigated. The working temperature of the stability test is 650 DEG C.

[0033] The battery prepared by the catalyst can be widely applied in the field of reversible proton ceramic electrochemical cells for hydrogen production and low-grade alkane conversion with medium and low temperature, high conversion efficiency and low cost.

[0034] Compared with the prior art, the present application has the following beneficial effects:

[0035] The fluorite-structured oxide PCO catalyst material of the present application exhibits excellent catalytic reaction performance due to its synergistic effect compared with praseodymium oxide or cerium oxide catalyst. By using different molar ratios, loadings and calcination temperatures, the surface morphology of the PBC oxygen electrode is modified by the PCO catalyst, which can effectively inhibit the segregation of Ba element and the valence change of Co element on the surface of the PBC oxygen electrode in a medium-temperature and high-humidity environment, thereby reducing the change of the lattice size of the PBC oxygen electrode. In addition, the PCO catalyst with high oxygen vacancies can also improve the surface ion exchange and diffusion coefficient of the PBC oxygen electrode, thereby improving the electrochemical activity. The electrochemical test results show that the electrochemical single cell of the oxygen electrode modified by using the catalyst material has lower polarization impedance and higher ORR / OER activity, and the highest power density of the single cell Ni-BZCYYb||BZCYYb||PCO-PBC is 1.77, 1.21 and 0.87 W cm -2 When humidified air is introduced on the oxygen electrode side, the electrochemical cell is operated in electrolysis mode, and the current density is 3.71, 2.69 and 2.09 A cm -2, excellent long-term stability and high power density (battery mode FC) / current density (electrolysis mode EL) are obtained. The above performance and technical index is superior to the performance and technical index of prior art, and the catalytic performance of the fluorite structure oxide PCO catalyst material is significantly improved. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 XRD comparison chart of PBC oxygen electrode material, PCO catalyst material and PCO-PBC mixed powder involved in the present application;

[0037] Figure 2 Impedance spectrum of PCO-PBC oxygen electrode involved in the present application, single cell (Ni-BZCYYb||BZCYYb||PCO-PBC) prepared by taking Ni-BZCYYb as fuel electrode support, tested in FC mode (humidified hydrogen gas is introduced into the fuel electrode side, and ambient air is used as the oxygen electrode side) at 600-700 ℃;

[0038] Figure 3 I-V-P curve of PCO-PBC oxygen electrode involved in the present application, single cell (Ni-BZCYYb||BZCYYb||PCO-PBC) prepared by taking Ni-BZCYYb as fuel electrode support, tested in FC mode (humidified hydrogen gas is introduced into the fuel electrode side, and ambient air is used as the oxygen electrode side) at 600-700 ℃;

[0039] Figure 4 Impedance spectrum of PBC oxygen electrode involved in the present application, single cell (Ni-BZCYYb||BZCYYb||PBC) prepared by taking Ni-BZCYYb as fuel electrode support, tested in FC mode (humidified hydrogen gas is introduced into the fuel electrode side, and ambient air is used as the oxygen electrode side) at 600-700 ℃;

[0040] Figure 5 I-V-P curve of PBC oxygen electrode involved in the present application, single cell (Ni-BZCYYb||BZCYYb||PBC) prepared by taking Ni-BZCYYb as fuel electrode support, tested in FC mode (humidified hydrogen gas is introduced into the fuel electrode side, and ambient air is used as the oxygen electrode side) at 600-700 ℃;

[0041] Figure 6 Voltage output chart of PBC and PCO-PBC oxygen electrode involved in the present application, single cell (Ni-BZCYYb||BZCYYb||PBC) and (Ni-BZCYYb||BZCYYb||PCO-PBC) prepared by taking Ni-BZCYYb as fuel electrode support, tested in FC mode-0.5Acm 2 at 650 ℃ (humidified hydrogen gas is introduced into the fuel electrode side, and ambient air is used as the oxygen electrode side).

[0042] Figure 7 I-V curve of the single cell (Ni-BZCYYb||BZCYYb||PCO-PBC) prepared by the fuel electrode support of the PCO-PBC oxygen electrode involved in the present application under EL mode (humidified hydrogen was introduced into the fuel electrode side and humidified air was introduced into the oxygen electrode side) at 600-700 ℃;

[0043] Figure 8 FC and EL mode (±0.5 Acm-2, constant current input) cycle stability diagram of the single cell of the single cell (Ni-BZCYYb||BZCYYb||PCO-PBC) prepared by the fuel electrode support of the PCO-PBC oxygen electrode involved in the present application at 650 ℃; 2 I-V curve of the single cell (Ni-BZCYYb||BZCYYb||PCO-PBC) prepared by the fuel electrode support of the PCO-PBC oxygen electrode involved in the present application under EL mode (humidified hydrogen was introduced into the fuel electrode side and humidified air was introduced into the oxygen electrode side) at 600-700 ℃;

[0044] Figure 9 SEM diagram of the single cell of the single cell (Ni-BZCYYb||BZCYYb||PCO-PBC) prepared by the fuel electrode support of the PCO-PBC oxygen electrode involved in the present application;

[0045] Figure 10 SEM diagram of the PCO-PBC oxygen electrode of the single cell of the single cell (Ni-BZCYYb||BZCYYb||PCO-PBC) prepared by the fuel electrode support of the PCO-PBC oxygen electrode involved in the present application after long-term test;

[0046] Figure 11 Comparison diagram of the highest power output density of the battery mode of the PCO-PBC oxygen electrode of the present application and the background technology PBCFN oxygen electrode on the single cell prepared by the fuel electrode support of the Ni-BZCYYb involved in the present application at 600-700 ℃;

[0047] Figure 12 Comparison diagram of the 1.3 V current output density of the electrolysis mode of the PCO-PBC oxygen electrode of the present application and the background technology PBCFN oxygen electrode on the single cell prepared by the fuel electrode support of the Ni-BZCYYb involved in the present application at 600-700 ℃;

[0048] Figure 13 Comparison diagram of the long-term performance of the symmetrical cell of the PCO catalyst of the present application and the background technology PBCFN oxygen electrode on the single cell prepared by the fuel electrode support of the Ni-BZCYYb involved in the present application. DETAILED DESCRIPTION

[0049] The present application will be further described in conjunction with specific embodiments, but the embodiments of the present application are not limited thereto.

[0050] Example 1: Synthesis of fluorite-structured oxide PCO catalyst

[0051] Take 0.044 g (1*10 -4 mol) praseodymium nitrate Pr(NO3)3·6H2O, 0.391 g (9*10 -4 mol) cerium nitrate Ce(NO3)3·6H2O, 0.075 g glycine, and 0.022 g polyvinylpyrrolidone PVP, and mix them with 10 mL of deionized water. Shake the mixture without heating to obtain a clear, precipitate-free solvent. Let it stand for more than one hour until the upper foam disappears and no precipitate appears. A precursor mixed solution is obtained. At this time, the concentrations of Pr and Ce in the mixed solution are 0.1 M (i.e., the molar concentrations of Pr and Ce).

[0052] In the present application, the molar ratio of Pr to Ce is Pr 0.1 Ce 0.9 O 2+δ The performance is the best and is superior to Pr 0.2 Ce 0.8 O 2+δ and CeO 2+δ .

[0053] Example 2: Preparation method of PBC oxygen electrode material framework

[0054] The PBC oxygen electrode material is prepared by the sol-gel method. According to the stoichiometric ratio, take 8.700 g of praseodymium nitrate Pr(NO3)3·6H2O, 4.704 g of barium nitrate Ba(NO3)2, and 11.641 g of cobalt nitrate Co(NO3)2·6H2O, mix them, and add deionized water to 200 mL and stir until dissolved. Then take 6.606 g of glycine and 18.492 g of citric acid monohydrate as complexing agents and add them to the solution at the same time. Heat and stir the mixed nitrate solution obtained in the foregoing process, and the heating temperature can be selected as 80 ℃. Stir until the solution turns into a deep red gel. Then move the gel to a forced air drying oven and dry it at 300 ℃ for 1 hour to ensure that the entire nitrate salt completes the explosion process. After taking out the precursor, move it to a muffle furnace and increase the temperature to 1000 ℃ at a rate of 2 ℃ / min, and then heat it at a constant temperature for 2 hours. After taking it out, PBC oxygen electrode powder is obtained.

[0055] The phases of the PBC oxygen electrode powder, the PCO catalyst powder (dry the mixed solution of Example 1 at 900 ℃ and heat it at a constant temperature for 2 hours to obtain the catalyst powder), and the mixed powder (the mass ratio of the PBC oxygen electrode powder to the PCO catalyst powder is 1:1) are shown in the XRD as shown in Figure 1 The PBC and PCO maintain chemical stability with each other.

[0056] Example 3: Preparation of PCO-PBC single cell

[0057] (1) Preparation method of fuel electrode supported proton conductor half cell

[0058] The electrolyte used in the half cell of the present application is BaZr 0.1 Ce 0.7 Y 0.1 Yb 0.1 O 3-δ (BZCYYb1711); the fuel electrode material is a composite fuel electrode composed of NiO and BZCYYb1711 electrolyte, and the mass ratio of NiO to BZCYYb1711 electrolyte in the composite fuel electrode is 6:4; the fuel electrode supported proton conductor half cell is prepared by co-casting.

[0059] (2) Preparation method of PBC oxygen electrode

[0060] 1.00 g of PBC oxygen electrode powder prepared in Example 2, 0.76 g of terpineol, and 0.04 g of ethyl cellulose are weighed into a mortar and ground for 1 hour to obtain the required oxygen electrode slurry; the prepared oxygen electrode slurry is uniformly coated on the prepared fuel electrode supported proton conductor half cell by screen printing method, and then placed in an oven for preliminary drying, and then placed in a high temperature muffle furnace and calcined at 950 ℃ for 2 h to obtain the required single cell.

[0061] (3) Method of PCO catalyst impregnated in PBC oxygen electrode

[0062] The PCO catalyst (mixed solution) prepared in Example 1 is impregnated on the PBC oxygen electrode framework (i.e. the PBC oxygen electrode side of the single cell) by a micro-sampler; the impregnation amount is controlled at 5-10 μL each time and can be impregnated in multiple times, and after each impregnation, it is moved to a forced air drying oven and dried at 80 ℃; after the PCO catalyst is impregnated on the PBC oxygen electrode framework and completely dried, it is moved to a muffle furnace and heated to 900 ℃ at a heating rate of 2 ℃ / min, and then calcined at constant temperature for 2 hours. The density of the PCO catalyst impregnated on the PBC oxygen electrode framework is 15 mg / cm 2 .

[0063] Performance test:

[0064] (1) Performance test of PCO-PBC single cell after catalyst impregnation

[0065] The humidified hydrogen (3 vol.% water + 97 vol.% hydrogen) was fed to the fuel electrode side and ambient air was fed to the oxygen electrode side. The impedance spectra (as shown in Figure 2 ) and I-V-P plots (as shown in Figure 3 ) of the single cell (Ni-BZCYYb|| BZCYYb|| PCO-PBC) prepared with PBC oxygen electrode and Ni-BZCYYb as fuel electrode support were tested in the range of 600-700 °C.

[0066] (2) The performance test of the blank PBC single cell in the control group.

[0067] The humidified hydrogen (3 vol.% water + 97 vol.% hydrogen) was fed to the fuel electrode side and ambient air was fed to the oxygen electrode side. The impedance spectra (as shown in Figure 4 ) and I-V-P plots (as shown in Figure 5 ) of the single cell (Ni-BZCYYb|| BZCYYb|| PBC) prepared with PBC oxygen electrode and Ni-BZCYYb as fuel electrode support were tested in the range of 600-700 °C.

[0068] (3) The FC stability test of the single cell with PBC and PCO-PBC oxygen electrode.

[0069] The humidified hydrogen (3 vol.% water + 97 vol.% hydrogen) was fed to the fuel electrode side and ambient air was fed to the oxygen electrode side. The stability test of the single cell prepared with PBC and PCO-PBC oxygen electrode and Ni-BZCYYb as fuel electrode support was tested in FC mode-0.5 A cm 2 under constant current input at 650 °C, as shown in Figure 6 .

[0070] (4) The EL performance test of the single cell with PCO-PBC oxygen electrode.

[0071] The humidified hydrogen (3 vol.% water + 97 vol.% hydrogen) was fed to the fuel electrode side and humidified air (3 vol.% water + 97 vol.% air) was fed to the oxygen electrode side. The I-V curves of the single cell (Ni-BZCYYb|| BZCYYb|| PCO-PBC) prepared with PCO-PBC oxygen electrode and Ni-BZCYYb as fuel electrode support were tested in the range of 600-700 °C in EL mode, as shown in Figure 7 . The reversible test was performed on the single cell, i.e. the current of ±0.5 A cm -2 was applied, and the electrochemical cell was alternately operated in FC and EL modes for 2 hours each time, and the oxygen electrode stability was investigated by such a cycle for 50 times, as shown in Figure 8As shown. The operating temperature for the stability test was 650℃.

[0072] (5) Microstructure of PCO-PBC oxygen electrode single cell.

[0073] After long-term stability testing, the cross-section of the single cell (Ni-BZCYYb||BZCYYb||PCO-PBC) (Example 3), prepared with a PCO-PBC oxygen electrode and Ni-BZCYYb as the fuel electrode support, was characterized by SEM. Figure 9 As shown, its oxygen electrode maintains a porous structure with a thickness of approximately 30 μm, while the electrolyte is 10 μm thick and dense. A dense film structure of the PCO catalyst can be clearly observed on the surface of the oxygen electrode, such as... Figure 10 As shown.

[0074] (6) Performance comparison of PCO-PBC oxygen electrode single cell with background technology.

[0075] A comparison of the highest power output density in battery mode tested in the range of 600–700 °C for a single cell fabricated with Ni-BZCYYb as the fuel electrode support, using the PCO-PBC oxygen electrode prepared in Example 3 of this invention and the PBCFN oxygen electrode (“An Efficient Steam-Induced Heterostructured Air Electrode for Protonic Ceramic Electrochemical Cells” K. Xu, H. Zhang, Y. Xu et al.) (as shown in the figure). Figure 11 A comparison chart of the current output density at 1.3V in electrolysis mode (as shown in the figure) and the current density at 1.3V in electrolysis mode (as shown in the figure) Figure 12 (As shown). The above performance and technical indicators are superior to those of the prior art, and the catalytic performance of the PCO catalyst material is significantly improved.

[0076] Figure 13 This invention relates to catalysts with different Pr / Ce molar ratios, and compares the long-term performance of symmetrical cells impregnated with different PCO catalysts on a PBC oxygen electrode. Among them, Pr... 0.2 Ce 0.8 O 2+δ - The preparation of PBC is the same as in Example 3, except that Pr 0.2 Ce 0.8 O 2+δ The molar ratio is different from that in Example 1, but other conditions are the same.

[0077] The fluorite-structured PCO catalyst material involved in the present application exhibits excellent catalytic reaction performance due to its synergistic effect compared with praseodymium oxide or cerium oxide catalyst. By using different molar ratios, impregnation amounts and calcination temperatures, the surface morphology of the PBC oxygen electrode is modified by the PCO catalyst, which can effectively inhibit the segregation of Ba element and the valence change of Co element in the medium-temperature and high-humidity environment, as shown in Figure 10 , thereby reducing the change in lattice size of the PBC oxygen electrode. In addition, the PCO catalyst with high oxygen vacancies can also improve the electrochemical activity of the surface of the PBC oxygen electrode. As shown in Figure 2 , 3, 4 and 5, the electrochemical test results show that the use of the catalyst material can make the electrochemical single cell of the modified oxygen electrode have lower polarization impedance and higher ORR / OER activity, as shown in Figure 5 , the highest power density of the single cell Ni-BZCYYb||BZCYYb||PCO-PBC at 700, 650 and 600 ℃ is 1.77, 1.21 and 0.87 W cm -2 , respectively. When the humidified air is introduced on the oxygen electrode side, the electrochemical cell is operated in the electrolysis mode, and the current density at 1.3 V voltage at 700, 650 and 600 ℃ is 3.71, 2.69 and 2.09 A cm -2 , respectively. As shown in Figure 6 and 7, excellent long-term stability and high power density (cell mode) / current density (electrolysis mode) are obtained. As shown in Figure 11 and 12, the performance and technical indicators of the battery of the present application are better than those of the prior art, and the catalytic performance of the PCO catalyst material is significant.

Claims

1. The application of a fluorite-structured catalyst modified in the oxygen electrode of a reversible proton ceramic battery, characterized in that: The fluorite-structured catalyst modified for the oxygen electrode of the reversible proton ceramic battery is used to prepare PrBaCo2O. 5+δ A reversible proton ceramic electrochemical cell with an oxygen electrode; The fluorite-structured catalyst used to modify the oxygen electrode of the reversible proton ceramic battery has a composition of Pr x Ce 1-x O 2+δ x is 0.1; The preparation method of the fluorite-structured catalyst for modifying the oxygen electrode of the reversible proton ceramic battery includes the following steps: mixing praseodymium nitrate, cerium nitrate, glycine, polyvinylpyrrolidone and water evenly to obtain a mixed solution; impregnating the mixed solution onto a double perovskite oxygen electrode framework, drying, repeating the impregnation and drying, and then calcining at 800-1000℃ for 1-2 hours to obtain the fluorite-structured catalyst for modifying the oxygen electrode of the reversible proton ceramic battery. The mass ratio of praseodymium nitrate, cerium nitrate, glycine, and polyvinylpyrrolidone is 1:(3-9):(0.6-1.8):(0.2-0.6). The double perovskite oxygen electrode is a PBC oxygen electrode, i.e., PrBaCo2O. 5+δ Oxygen electrode.

2. The application according to claim 1, characterized in that: The amount of water added is such that the concentrations of praseodymium nitrate and cerium nitrate in the mixed solution are 0.05-0.3 mol / L; The term "immersion of the mixed solution on the double perovskite oxygen electrode framework" refers to drop-coating the mixed solution onto the double perovskite oxygen electrode framework; the amount of mixed solution added each time is 5-10 μL / 0.2826 cm. 2 ; The drying temperature is 60-80℃; The heating rate for calcination is 1-4 °C / min; The catalyst is loaded at a concentration of 5-30 mg / cm² on the PBC oxygen electrode framework. 2 ; Alternatively, glycine and polyvinylpyrrolidone can be replaced with octylphenyl polyoxyethylene ether; and water can be replaced with anhydrous ethanol.

3. The application according to claim 1, characterized in that: The preparation method of the PBC oxygen electrode material framework includes the following steps: (1) Preparation of PBC oxygen electrode material by sol-gel method: Pr(NO3)3·6H2O, Ba(NO3)2, and Co(NO3)2·6H2O were dissolved in water in stoichiometric ratio, and glycine and citric acid monohydrate were added to obtain a mixed solution; the mixed solution was then heated to 70-100 ℃ and stirred continuously until the solution became a dark red gel, and then the gel was dried at 160-300 ℃ for 1-2 hours; then the temperature was raised to 900-1100 ℃ and calcined at a constant temperature for 1-2 hours to obtain PBC oxygen electrode powder; wherein the molar ratio of total metal ions of praseodymium, barium, and cobalt to glycine to citric acid monohydrate was 1:0.6-1.2:0.6-1.2; (2) Weigh 1 g of PBC oxygen electrode powder, 0.76-1.14 g of terpineol and 0.04-0.08 g of ethyl cellulose and mix them to obtain oxygen electrode slurry; apply the oxygen electrode slurry evenly to the half cell supported by the fuel electrode by screen printing, dry it and place it in a muffle furnace at 800-1000 ℃ for 1-2 h to obtain the PBC oxygen electrode material skeleton.

4. The application according to claim 3, characterized in that: After drying the gel at 160-300℃ for 1-2 hours, it is transferred to a muffle furnace and heated at a rate of 1-4℃ / min.

5. The application according to claim 3, characterized in that: The structure of the half-cell supported by the fuel electrode is oxygen electrode / / electrolyte / / fuel electrode, that is, it includes an electrolyte, with an oxygen electrode and a fuel electrode on both sides of the electrolyte.

6. The application according to claim 5, characterized in that: The electrolyte is BaZr. 0.1 Ce 0.7 Y 0.1 Yb 0.1 O 3-δ ; The fuel electrode material is a composite fuel electrode composed of NiO and BZCYYb1711 electrolyte; the mass ratio of NiO and BZCYYb1711 electrolyte in the composite fuel electrode is 6:4.

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