Oxygen electrode material for proton conduction type reversible solid oxide battery and preparation method of oxygen electrode material

Abstract

The invention belongs to the technical field of solid oxide batteries, and relates to an oxygen electrode material for a proton conduction type reversible solid oxide battery, the oxygen electrode material is a perovskite type oxide, and the chemical formula is PrzBa < 1-0.5 z > Sr < 1-0.5 z > CouFe < 2-u-x-y > M < x > Y < y > O < 5 + delta >, in the formula, M is any one of Nb, Ta, Zr, Hf, Mo and W, x is more than or equal to 0.05 and less than or equal to 0.2, y is more than or equal to 0.05 and less than or equal to 0.15, z is more than or equal to 0.98 and less than or equal to 1.02, u is more than or equal to 1.48 and less than or equal to 1.52, and delta represents a non-stoichiometric oxygen vacancy. The oxygen electrode material prepared by co-doping M and Y according to a specific ratio has a relatively low thermal expansion coefficient, and is well matched with an electrolyte BCZYYb; when being used in a proton conduction type solid oxide fuel cell and a proton conduction type solid oxide electrolytic tank, the proton conduction type solid oxide fuel cell / proton conduction type solid oxide electrolytic cell has good electrochemical performance; and the oxygen electrode material has excellent long-term working stability.

Description

Technical Field

[0001] The present invention belongs to the technical field of solid oxide batteries, and particularly relates to an oxygen electrode material for a proton-conducting reversible solid oxide battery and a preparation method thereof. Background Art

[0002] Proton-conducting reversible solid oxide batteries (P-SOCs) are a clean energy power generation and long-term energy storage technology with great application potential. They can be used as proton-conducting solid oxide fuel cells (P-SOFCs) or proton-conducting solid oxide electrolyzers (P-SOECs). Compared with traditional oxygen ion conductors, proton conductors exhibit higher ionic conductivity and lower electronic conductivity in the medium and low temperature range (350 - 700 °C), and between adjacent two oxygen atoms, proton conduction has a lower migration activation energy (0.4 - 0.6 eV). A proton-conducting reversible solid oxide battery consists of a hydrogen electrode (anode), an electrolyte, and an oxygen electrode (cathode). Among them, significant breakthroughs have been made 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 respectively considered the most mature proton-conducting electrolytes and hydrogen electrode materials, and the development of high-performance oxygen electrode materials has become the focus of preparing efficient P-SOCs.

[0003] Currently, the double perovskite material PrBa 0.5 Sr 0.5 Co 1.5 Fe 0.5 O 5+δ (PBSCF), as a material with high catalytic activity for the oxygen evolution reaction (OER) and triple conductivity (oxygen ion, electron, and proton) characteristics, is widely used as the oxygen electrode material of P-SOCs. Ba and Co in PBSCF contribute to increasing the oxygen vacancy concentration. At the same time, the high alkalinity of Ba and Sr is conducive to the rapid dissociation and transport of the generated water at the interface. However, the large amounts of Ba, Co, and Sr make the thermal expansion coefficient (TEC) of PBSCF relatively high (about 23.7×10 -6 K -1 ), while the TEC of the BCZYYb electrolyte is relatively low (about 12.4×10 -6 K -1)Mismatch will cause excessive thermal stress and interfacial separation during the operation of the battery, resulting in problems such as poor battery stability and obvious performance degradation. To improve the TEC matching between the oxygen electrode material and the electrolyte, the methods of mechanically mixing the oxygen electrode material and the electrolyte material or element doping are generally adopted. The method of mechanically mixing the oxygen electrode material and the electrolyte material is simple and feasible. For example, Bingxue Hou et al. (Journal of Solid State Electrohemistry, 13 January 2025) compounded PBSCF and LaCo 0.6 Ni 0.4 O 3-δ (LCN) by the impregnation method to prepare a PBSCF-LCN composite oxygen electrode. The polarization resistance of the battery prepared from this composite oxygen electrode is 0.58 Ω·cm 2 , which is less than 1.23 Ω·cm of pure PBSCF 2 . A small polarization resistance indicates good TEC matching between the composite oxygen electrode and the electrolyte. However, this mechanical mixing method is not sufficient to ensure the uniformity of the composite material, so it is impossible to establish a sufficiently effective interface between the two components, and thus the problems of battery stability and obvious attenuation still exist. Element doping is an in-situ synthesis method, which is not only beneficial to establishing a stable and effective interface, but also beneficial to increasing the oxygen vacancy concentration of the material. Therefore, element doping is a better improvement strategy. However, in the prior art, there is little research on the element doping of PBSCF, and generally Zn, Ni or Mn elements are used to replace Co and Fe at the B site. For example, Wang Q et al. (Journal of Materials Chemistry A, 2020, 8(16): 7704-7712) prepared Pr2BaNiMnO 7-δ by replacing Co and Fe at the B site with Ni and Mn. The prepared Pr2BaNiMnO 7-δ has a low TEC, but its TEC matching with the excellent electrolyte BCZYYb (thermal expansion coefficient is about 12.4×10 -6 K -1 ) still needs to be improved. Summary of the Invention

[0004] In view of the problems that the thermal expansion coefficient (TEC) matching between the oxygen electrode material PBSCF and the electrolyte BCZYYb in the prior art needs to be further improved, and the stability and attenuation of the battery still exist, the present invention provides an oxygen electrode material for a proton-conducting reversible solid oxide battery and a preparation method thereof. The present invention adopts co-doping of transition metals, that is, co-doping of one of Nb, Zr, Ta, Mo, Hf, and W with Y, partially replacing Fe at the B site, to obtain a new doped PBSCF material, which is used as the oxygen electrode of a proton-conducting reversible solid oxide battery, and has the characteristics of low TEC, good matching with the electrolyte BCZYYb, and good battery stability.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] An oxygen electrode material for a proton-conducting reversible solid oxide battery is a perovskite-type oxide, and its chemical formula is Pr z Ba 1-0.5z Sr 1-0.5z Co u Fe 2-u-x-y M x Y y O 5+δ ; where M is any one of Nb, Ta, Zr, Hf, Mo, and W, 0.05 ≤ x ≤ 0.2, 0.05 ≤ y ≤ 0.15, 0.98 ≤ z ≤ 1.02, 1.48 ≤ u ≤ 1.52, and δ represents non-stoichiometric oxygen vacancies.

[0007] Pr z Ba 1-0.5z Sr 1-0.5z Co u Fe 2-u-x-y M x Y y O 5+δ It has a perovskite structure. The inventor found through research that the co-doping of transition metals M and Y partially replaces Fe at the B site, which can effectively reduce the thermal expansion coefficient of the PBSCF material. The reduction of the thermal expansion coefficient makes its matching with the thermal expansion coefficient of the electrolyte BCZYYb good, so that the contact between the oxygen electrode material and the electrolyte interface in the battery is good, and further the impedance of the battery can be reduced and its electrochemical performance can be improved; in addition, the co-doping of transition metals M and Y may also improve the OER activity, surface reaction exchange kinetics, and oxygen vacancy concentration, thereby further improving the electrochemical performance of the battery.

[0008] PrBa 0.5 Sr 0.5 Co 1.5 Fe 0.5 O 5+δ(PBSCF) has been proven to be a material with high catalytic activity for the oxygen evolution reaction (OER) and triple-conductive (oxygen ion, electron, and proton) properties. Pr in the present invention z Ba 1-0.5z Sr 1- 0.5z Co u Fe 2-u-x-y M x Y y O 5+δ is prepared by co-doping transition metal M and Y to partially replace Fe at the B-site on the basis of PBSCF. Therefore, the values of z and u need to be close to the molar fractions of Pr and Co in the matrix PrBa 0.5 Sr 0.5 Co 1.5 Fe 0.5 O 5+δ Otherwise, its conductive properties and OER activity will be affected. That is, z is close to 1, for example, it can be 0.98, 1, 1.02, preferably 1; u is close to 1.5, for example, it can be 1.48, 1.50, 1.52, preferably 1.

[0009] Preferably, M is Nb or Ta, more preferably Nb.

[0010] Preferably, 0.1 ≤ x ≤ 0.15, 0.08 ≤ y ≤ 0.12.

[0011] In a preferred technical solution of the present invention, the chemical formula of the oxygen electrode material for the proton-conducting reversible solid oxide battery is PrBa 0.5 Sr 0.5 Co 1.5 Fe 0.3 Nb 0.1 Y 0.1 O 5+δ .

[0012] The present invention also provides a preparation method for the foregoing oxygen electrode material for the proton-conducting reversible solid oxide battery, which is the sol-gel method and includes the following steps:

[0013] (S1) According to Pr z Ba 1-0.5z Sr 1-0.5z Co u Fe 2-u-x-y M x Y y O 5+δFor the stoichiometric ratio, dissolve the chelating agent and metal salts containing Pr, Ba, Sr, Co, Fe, M, and Y in water to form a mixed solution, then use a pH regulator to adjust the pH of the mixed solution to 7.5 - 8.5, and then heat and evaporate with stirring to obtain a gel; the molar ratio of the chelating agent to the total metal ions is (2 - 5):1, and the total metal ions are composed of Pr, Ba, Sr, Co, Fe, M, and Y ions;

[0014] (S2) Calcinate and crush the gel in an air atmosphere to obtain Pr z Ba 1-0.5z Sr 1-0.5z Co u Fe 2-u-x- y M x Y y O 5+δ powder, which is the oxygen electrode material for a proton-conducting reversible solid oxide fuel cell.

[0015] Further, in step (S1), the chelating agent is at least one of oxalic acid, citric acid, and ethylenediaminetetraacetic acid; the metal salt is a nitrate, oxalate, or halide salt of the metal; the pH regulator is ammonia water, sodium bicarbonate, or triethanolamine.

[0016] Further, in step (S2), the calcination is carried out at 900 - 1000 °C for 2 - 5 hours; preferably, the calcination is carried out by first holding at 450 - 550 °C for 0.5 - 1 hour and then calcining at 950 - 1000 °C for 2 - 5 hours.

[0017] Further, in step (S2), the crushing is carried out by air jet milling or ball milling, and the particle size of the Pr z Ba 1-0.5z Sr 1- 0.5z Co u Fe 2-u-x-y M x Y y O 5+δ powder is 300 - 600 mesh.

[0018] The present invention also provides the application of the foregoing oxygen electrode material in a proton-conducting solid oxide fuel cell (P-SOFC) using H2 as fuel.

[0019] The present invention also provides the application of the foregoing oxygen electrode material in a proton-conducting solid oxide electrolyzer (P-SOEC) for electrolyzing H2O or co-electrolyzing H2O-CO2.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] 1. The oxygen electrode material Pr is prepared by co-doping one of the transition metal elements Nb, Zr, Ta, Mo, Hf, and W with Y in a specific ratio. z Ba 1-0.5z Sr 1-0.5z Co u Fe 2-u-x-y M x Y y O 5+δ , which has a low thermal expansion coefficient and good compatibility with the electrolyte BCZYYb.

[0022] 2. When the oxygen electrode material Pr z Ba 1-0.5z Sr 1-0.5z Co u Fe 2-u-x-y M x Y y O 5+δ is used in a proton-conducting solid oxide fuel cell with H2 as the fuel, the cell has a high power density; when it is used in a solid oxide electrolyzer for electrolyzing H2O or co-electrolyzing H2O-CO2, the electrolyzer has a high current density; and this oxygen electrode material has excellent long-term working stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a self-made battery test device.

[0024] Figure 2 is the XRD pattern of PrBa 0.5 Sr 0.5 Co 1.5 Fe 0.3 Nb 0.1 Y 0.1 O 5+δ (PBSCFNY).

[0025] Figure 3 is the cross-sectional SEM image of the battery assembled using the oxygen electrode material prepared in Example 1 in Application Example 1.

[0026] Figure 4 is the test curve of ohmic impedance and polarization impedance of the battery prepared in Application Example 1 at 750 °C, 700 °C, 650 °C, and 600 °C when using humidified H2 as the fuel.

[0027] Figure 5 is the curve of voltage and peak power density varying with current density of the battery assembled in Application Example 1 at 750 °C, 700 °C, 650 °C, and 600 °C when using humidified H2 as the fuel.

[0028] Figure 6Peak power density comparison chart of two kinds of batteries in Application Example 1 and Comparative Application Example 1 at various temperatures.

[0029] Figure 7 For the battery assembled in Application Example 1 during the electrolysis of H2O, the voltage vs. current density curves at 750 °C, 700 °C, 650 °C, and 600 °C.

[0030] Figure 8 For the battery assembled in Application Example 1 during the co-electrolysis of CO2-H2O, the voltage vs. current density curves at 750 °C, 700 °C, 650 °C, and 600 °C.

[0031] Figure 9 Voltage vs. time curves of the single cell assembled in Application Example 1 and the battery assembled in Comparative Application Example 1. Detailed implementation manners

[0032] The present invention will be further described below in conjunction with specific embodiments, but the present invention is not limited to the following embodiments.

[0033] In the following embodiments, the experimental methods are conventional methods unless otherwise specified; the reagents and materials can be obtained from commercial sources unless otherwise specified.

[0034] Example 1 - Preparation of oxygen electrode material PrBa 0.5 Sr 0.5 Co 1.5 Fe 0.3 Nb 0.1 Y 0.1 O 5+δ (M is Nb, x = 0.1, y = 0.1, z = 1, u = 1.5)

[0035] (S1) According to the stoichiometric ratio of the chemical formula PrBa 0.5 Sr 0.5 Co 1.5 Fe 0.3 Nb 0.1 Y 0.1 O 5+δ Dissolve praseodymium nitrate Pr(NO3)3·6H2O), barium nitrate (Ba(NO3)2), strontium nitrate (Sr(NO3)2·6H2O), cobalt nitrate (Co(NO3)2·6H2O), iron nitrate (Fe(NO3)3·9H2O), niobium oxalate hydrate (C2H4NbO5), and yttrium nitrate (Y(NO3)3·6H2O) in water to form a solution; then weigh citric acid and ethylenediaminetetraacetic acid according to citric acid:ethylenediaminetetraacetic acid:total metal ions = 2:1:1 (molar ratio) and dissolve them in the above solution to form a mixed solution; then adjust the pH of the mixed solution to 8.0 with ammonia water, and heat and evaporate with stirring to obtain a gel;

[0036] (S2) After keeping the gel in a muffle furnace at 500 °C for 1 hour, it is then calcined in air at 950 °C for 2 hours. After cooling, the calcined product is pulverized by air flow to 300 - 400 mesh to obtain the oxygen electrode material PrBa 0.5 Sr 0.5 Co 1.5 Fe 0.3 Nb 0.1 Y 0.1 O 5+δ powder.

[0037] Example 2 - Preparation of the oxygen electrode material PrBa 0.5 Sr 0.5 Co 1.5 Fe 0.4 Nb 0.05 Y 0.05 O 5+δ

[0038] The rest is the same as in Example 1, except that: the ratios of M and Y are different, x = 0.05, y = 0.05; correspondingly, the ingredients are proportioned according to the stoichiometric ratios of the respective elements of PrBa 0.5 Sr 0.5 Co 1.5 Fe 0.4 Nb 0.05 Y 0.05 O 5+δ corresponding.

[0039] Example 3 - Preparation of the oxygen electrode material PrBa 0.5 Sr 0.5 Co 1.5 Fe 0.32 Nb 0.1 Y 0.08 O 5+δ

[0040] The rest is the same as in Example 1, except that: the ratios of M and Y are different, x = 0.1, y = 0.08; correspondingly, the ingredients are proportioned according to the stoichiometric ratios of the respective elements of PrBa 0.5 Sr 0.5 Co 1.5 Fe 0.32 Nb 0.1 Y 0.08 O 5+δ corresponding.

[0041] Example 4 - Preparation of the oxygen electrode material PrBa 0.5 Sr 0.5 Co 1.5 Fe 0.23 Nb 0.15Y 0.12 O 5+δ

[0042] The rest is the same as in Example 1, except that: the ratio of M and Y is different, x = 0.15, y = 0.12; correspondingly, charge the materials according to the stoichiometric ratios of the respective elements of PrBa 0.5 Sr 0.5 Co 1.5 Fe 0.23 Nb 0.15 Y 0.12 O 5+δ corresponding thereto.

[0043] Example 5 - Preparation of oxygen electrode material PrBa 0.5 Sr 0.5 Co 1.5 Fe 0.15 Nb 0.2 Y 0.15 O 5+δ

[0044] The rest is the same as in Example 1, except that: the ratio of M and Y is different, x = 0.2, y = 0.15; correspondingly, charge the materials according to the stoichiometric ratios of the respective elements of PrBa 0.5 Sr 0.5 Co 1.5 Fe 0.15 Nb 0.2 Y 0.15 O 5+δ corresponding thereto.

[0045] Example 6 - Preparation of oxygen electrode material PrBa 0.5 Sr 0.5 Co 1.5 Fe 0.3 Ta 0.1 Y 0.1 O 5+δ

[0046] The rest is the same as in Example 1, except that: the type of M is different, M is Ta, and at the same time, the calcination conditions in step (S2) are different. The specific steps are as follows:

[0047] (S1) According to the chemical formula PrBa 0.5 Sr 0.5 Co 1.5 Fe 0.3 Ta 0.1 Y 0.1 O 5+δFor the stoichiometric ratio, dissolve praseodymium nitrate Pr(NO3)3·6H2O), barium nitrate (Ba(NO3)2), strontium nitrate (Sr(NO3)2·6H2O), cobalt nitrate (Co(NO3)2·6H2O), iron nitrate (Fe(NO3)3·9H2O), tantalum pentachloride (TaCl5) and yttrium nitrate (Y(NO3)3·6H2O) in water to form a solution; then weigh citric acid and ethylenediaminetetraacetic acid according to citric acid:ethylenediaminetetraacetic acid:total metal ions = 2.5:1:1 (molar ratio) and dissolve them in the above solution to form a mixed solution; then use ammonia water to adjust the pH of the mixed solution to 8.0, and heat and evaporate with stirring to obtain a gel;

[0048] (S2) Calcinate the gel in a muffle furnace in air at 900 °C for 4 hours, and after cooling, pulverize the calcined product by air flow to 300 - 400 mesh to obtain the oxygen electrode material PrBa 0.5 Sr 0.5 Co 1.5 Fe 0.3 Ta 0. 1Y 0.1 O 5+δ powder.

[0049] Example 7 - Preparation of oxygen electrode material PrBa 0.5 Sr 0.5 Co 1.5 Fe 0.3 Hf 0.1 Y 0.1 O 5+δ

[0050] The rest is the same as in Example 1, except that: the type of M is different, M is Hf, and correspondingly, the ingredients are carried out according to the stoichiometric ratio of each element corresponding to the chemical formula PrBa 0.5 Sr 0. 5Co 1.5 Fe 0.3 Hf 0.1 Y 0.1 O 5+δ Specific steps are as follows:

[0051] (S1) According to the chemical formula PrBa 0.5 Sr 0.5 Co 1.5 Fe 0.3 Hf 0.1 Y 0.1 O 5+δAccording to the stoichiometric ratio of PrBa

[0052] (S2) The same as Example 1.

[0053] Example 8 - Preparation of oxygen electrode material PrBa 0.5 Sr 0.5 Co 1.5 Fe 0.3 Mo 0.1 Y 0.1 O 5+δ

[0054] The rest is the same as in Example 1, except that: the type of M is different, M is Mo, and accordingly, the ingredients are prepared according to the stoichiometric ratio of the corresponding elements in the chemical formula PrBa 0.5 Sr 0. 5Co 1.5 Fe 0.3 Mo 0.1 Y 0.1 O 5+δ The specific steps are as follows:

[0055] (S1) According to the stoichiometric ratio of PrBa 0.5 Sr 0.5 Co 1.5 Fe 0.3 Hf 0.1 Y 0.1 O 5+δ Praseodymium nitrate Pr(NO3)3·6H2O), barium nitrate (Ba(NO3)2), strontium nitrate (Sr(NO3)2·6H2O), cobalt nitrate (Co(NO3)2·6H2O), iron nitrate (Fe(NO3)3·9H2O), hafnium tetrachloride (HfCl4) and yttrium nitrate (Y(NO3)3·6H2O) are dissolved in water to form a solution; then citric acid and ethylenediaminetetraacetic acid are weighed according to citric acid:ethylenediaminetetraacetic acid:total metal ions = 2.5:1:1 (molar ratio) and dissolved in the above solution to form a mixed solution; then the pH of the mixed solution is adjusted to 8.0 with ammonia water, and it is heated and evaporated with stirring to obtain a gel;

[0056] (S2)Same as Example 1.

[0057] Example 9 - Preparation of oxygen electrode material PrBa 0.5 Sr 0.5 Co 1.5 Fe 0.3 Zr 0.1 Y 0.1 O 5+δ

[0058] The rest is the same as in Example 1, except that the type of M is different. M is Zr. Accordingly, the ingredients are proportioned according to the stoichiometric ratios of the corresponding elements in the chemical formula PrBa 0.5 Sr 0. 5Co 1.5 Fe 0.3 Zr 0.1 Y 0.1 O 5+δ The specific steps for proportioning are as follows:

[0059] (S1)According to the stoichiometric ratio of the chemical formula PrBa 0.5 Sr 0.5 Co 1.5 Fe 0.3 Hf 0.1 Y 0.1 O 5+δ Dissolve praseodymium nitrate Pr(NO3)3·6H2O), barium nitrate (Ba(NO3)2), strontium nitrate (Sr(NO3)2·6H2O), cobalt nitrate (Co(NO3)2·6H2O), iron nitrate (Fe(NO3)3·9H2O), zirconium chloride (ZrCl4) and yttrium nitrate (Y(NO3)3·6H2O) in water to form a solution; then weigh citric acid and ethylenediaminetetraacetic acid according to citric acid:ethylenediaminetetraacetic acid:total metal ions = 2.5:1:1 (molar ratio) and dissolve them in the above solution to form a mixed solution; then use ammonia water to adjust the pH of the mixed solution to 8.0, and heat and evaporate with stirring to obtain a gel;

[0060] (S2)Same as Example 1.

[0061] Example 10 - Preparation of oxygen electrode material PrBa 0.5 Sr 0.5 Co 1.5 Fe 0.3 W 0.1 Y 0.1 O 5+δ

[0062] The rest is the same as in Example 1, except that the type of M is different. M is W. Accordingly, the ingredients are proportioned according to the chemical formula PrBa 0.5 Sr 0.5 Co 1.5 Fe0.3 W 0.1 Y 0.1 O 5+δ Weigh the ingredients according to the stoichiometric ratios of the corresponding elements. The specific steps are as follows:

[0063] (S1) According to the chemical formula PrBa 0.5 Sr 0.5 Co 1.5 Fe 0.3 Hf 0.1 Y 0.1 O 5+δ Dissolve praseodymium nitrate Pr(NO3)3·6H2O), barium nitrate (Ba(NO3)2), strontium nitrate (Sr(NO3)2·6H2O), cobalt nitrate (Co(NO3)2·6H2O), iron nitrate (Fe(NO3)3·9H2O), tungsten hexachloride (WCl6) and yttrium nitrate (Y(NO3)3·6H2O) in water to form a solution; then weigh citric acid and ethylenediaminetetraacetic acid according to citric acid:ethylenediaminetetraacetic acid:total metal ions = 2.5:1:1 (molar ratio) and dissolve them in the above solution to form a mixed solution; then use ammonia water to adjust the pH of the mixed solution to 8.0, and heat and evaporate with stirring to obtain a gel;

[0064] (S2) The same as in Example 1.

[0065] Comparative Example 1 - Preparation of oxygen electrode material PrBa 0.5 Sr 0.5 Co 1.5 Fe 0.4 Y 0.1 O 5+δ

[0066] The rest is the same as in Example 1, except that there is no Nb, that is, only Y is doped; correspondingly, weigh the ingredients according to the stoichiometric ratios of the corresponding elements in the chemical formula PrBa 0.5 Sr 0.5 Co 1.5 Fe 0.4 Y 0.1 O 5+δ

[0067] Comparative Example 2 - Preparation of oxygen electrode material PrBa 0.5 Sr 0.5 Co 1.5 Fe 0.4 Nb 0.1 O 5+δ

[0068] The rest is the same as in Example 1, except that there is no Y, that is, only Nb is doped; correspondingly, weigh the ingredients according to the chemical formula PrBa 0.5 Sr 0.5 Co​1.5 Fe 0.4 Nb 0.1 O 5+δ Ingredient proportioning is carried out according to the stoichiometric ratios of the corresponding elements.

[0069] Comparative Example 3 - Preparation of the oxygen electrode material PrBa 0.5 Sr 0.5 Co 1.5 Fe 0.4 Zn 0.1 Y 0.1 O 5+δ

[0070] The rest is the same as in Example 1, except that: the type of M is different, M is Zn; correspondingly, ingredient proportioning is carried out according to the stoichiometric ratios of the corresponding elements in the chemical formula PrBa 0.5 Sr 0. 5Co 1.5 Fe 0.4 Zn 0.1 Y 0.1 O 5+δ Ingredient proportioning is carried out according to the stoichiometric ratios of the corresponding elements.

[0071] Application Example 1

[0072] The oxygen electrode material PrBa prepared in Example 1 0.5 Sr 0.5 Co 1.5 Fe 0.3 Nb 0.1 Y 0.1 O 5+δ is used in P-SOCs. The specific assembly process is as follows:

[0073] (1) Mix the powder composed of 51 wt% NiO, 34 wt% BaCe 0.7 Zr 0.1 Y 0.1 Yb 0.1 O 3-δ (BCZYYb) and 15 wt% starch in ethanol and ball mill for 24 hours, then dry and uniaxially press into a tablet with a diameter of 15 mm, and then sinter at 1100 °C for 2 hours to form a green porous anode substrate.

[0074] (2) Mix 1 wt% NiO as a sintering aid with the BCZYYb powder, fully disperse it in an organic dispersant to form a stable suspension, then drop it onto the center of the anode substrate prepared in step (1), and immediately rotate 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), and then dry at room temperature to remove the solvent in the BCZYYb layer to obtain an anode-electrolyte bilayer structure.

[0075] (3) The subsequent anode-electrolyte bilayer structure was co-sintered in a muffle furnace at 1450 °C for 5 hours to obtain a dense BCZYYb electrolyte, thereby fabricating a half cell.

[0076] (4) The oxygen electrode material PrBa 0.5 Sr 0.5 Co 1.5 Fe 0.3 Nb 0.1 Y 0.1 O 5+δ prepared in Example 1 was added to a mortar with an organic solvent (terpineol: ethyl cellulose = 96:4) at a mass ratio of 1:1.5 and ground for 1 hour to obtain an oxygen electrode material slurry; then the oxygen electrode material slurry was coated on the surface of the electrolyte sintered in step (3) by means of screen printing; after drying, the sample was calcined at 950 °C for 4 hours to complete the fabrication of the entire single cell.

[0077] The single cell was tested using a self-made test device ( Figure 1 as shown). Specifically, the single cell was sealed on an alumina tube using conductive silver paste, and silver wires were used as the connecting wires for the cathode and anode. To evaluate the cell performance using H2 fuel and the performance of the electrolyzer for electrolyzing H2O and co-electrolyzing CO2-H2O, approximately 3% by volume of water vapor was generated by a water bubbler at room temperature before introducing the fuel into the cell. The gas flow rate was set to 20 ml / min for all gases. The power output performance and electrolysis of the cell were tested using a Thales cell test system. The AC impedance spectrum was tested using a Zennium electrochemical workstation in the frequency range of 0.01 Hz to 1 MHz with an AC perturbation of 10 mV.

[0078] Application Example 2-10

[0079] The rest was the same as in Application Example 1, except that the oxygen electrode materials in step (4) were prepared in Examples 2-10.

[0080] Comparative Application Examples 1-3

[0081] The rest was the same as in Application Example 1, except that the oxygen electrode materials in step (4) were prepared in Comparative Examples 1-3.

[0082] Results and Analysis

[0083] The above-mentioned examples, comparative examples, application examples, and comparative application examples were tested and characterized, and the results and analysis are as follows:

[0084] I. Structural Performance

[0085] PrBa prepared in Example 1 0.5 Sr0.5 Co 1.5 Fe 0.3 Nb 0.1 Y 0.1 O 5+δ (PBSCFNY)'s XRD pattern is as follows Figure 2 shown; the cross-sectional SEM image of the battery assembled with the oxygen electrode material PBSCFNY prepared in Example 1 in Application Example 1 is as follows Figure 3 shown.

[0086] It can be seen from Figure 2 that the diffraction peaks of PBSCFNY all correspond to the main diffraction peaks of PrBaCo2O 5+δ represented by the PDF standard card (PDF No#: 01-075-7610) of PrBaCo2O 5+δ , proving that PBSCFNY after doping with Nb and Y elements still maintains the perovskite structure without being destroyed.

[0087] It can be seen from Figure 3 that the interface contact between the oxygen electrode, electrolyte, and hydrogen electrode is good.

[0088] II. Thermal Expansion Coefficient (TEC) Test

[0089] The thermal expansion coefficient of the oxygen electrode materials prepared in each example and comparative example was tested by a thermomechanical analyzer. The specific method was as follows: The material powder was pressed into a strip with a size of 1m×6mm×10mm. The test temperature range was 50 - 1000°C, the heating rate was 5°C / min, and the sample length was recorded every 50°C. The thermal expansion rate at the corresponding temperature was calculated according to the following formula in combination with the temperature change; then, with the thermal expansion rate as the ordinate and the temperature as the abscissa, a thermal expansion rate - temperature curve was plotted, and the slope after linear fitting was the thermal expansion coefficient of the oxygen electrode material at 50 - 1000°C.

[0090] Thermal expansion coefficient α = (L - L0) / L0

[0091] In the formula, L is the length of the sample at temperature T, and L0 is the length of the sample at 50°C. The test results of the thermal expansion coefficients of the oxygen electrode materials prepared in each example and comparative example are shown in Table 1.

[0092] Table 1 Thermal Expansion Coefficient

[0093]

[0094] It can be seen from Table 1 that compared with the thermal expansion coefficient (TEC) of PBSCF, which is 23.7×10 -6 K -1 the oxygen electrode material PrBa 0.5 Sr0.5 Co 1.5 Fe 0.4-x M x Y y O 5+δ The coefficients of thermal expansion of all are significantly lower. The coefficients of thermal expansion of Preferred Examples 1, 3, 4, and 6 do not exceed 16.0×10 -6 K -1 , and in particular, the coefficient of thermal expansion of the optimal Example 1 is only 14.64×10 -6 K -1 , which is closest to the coefficient of thermal expansion of 12.4×10 -6 K -1 of the BCZYYb electrolyte material.

[0095] III. Electrochemical Performance

[0096] a) Ohmic impedance and polarization impedance: When the single cell prepared in Application Example 1 uses humidified H2 (3% H2O) as fuel, the test curves of ohmic impedance and polarization impedance at 750 °C, 700 °C, 650 °C, and 600 °C are as shown in Figure 4 . It can be seen from the figure that as the temperature decreases, both the ohmic impedance and the polarization impedance show an increasing trend. Comparatively speaking, the increasing trend of the polarization impedance is greater. At 600 °C, the polarization impedance exceeds the ohmic impedance and is the main source of the cell impedance.

[0097] The polarization impedance test results at 600 °C of the cells of each application example and comparative application example when using humidified H2 (3% H2O) as fuel are shown in Table 2.

[0098] b) Peak power density of the solid oxide fuel cell: When the cell assembled in Application Example 1 uses humidified H2 as fuel, the curves of voltage and peak power density varying with current density at 750 °C, 700 °C, 650 °C, and 600 °C are as shown in Figure 5 ; the comparison diagrams of the peak power densities of the two cells in Application Example 1 and Comparative Application Example 1 at each temperature are as shown in Figure 6 . It can be seen from Figure 5 and Figure 6 that the power density of the cell in Application Example 1 is significantly higher than that of the cell in Comparative Application Example 1 at each temperature.

[0099] The test results of the peak power densities of the cells of each application example and comparative application example when using humidified H2 as fuel at 650 °C are shown in Table 2.

[0100] c) Current density of the solid oxide electrolytic cell:

[0101] For the cell assembled in Application Example 1 during the electrolysis of H2O (with the hydrogen electrode feed being 97% H2 + 3% H2O and the oxygen electrode feed being 20% H2O + 80% argon), the current density vs. voltage curves at 750 °C, 700 °C, 650 °C, and 600 °C are as Figure 7 shown. It can be obtained from Figure 7 that the current density is relatively high at each temperature. At 750 °C, 700 °C, 650 °C, and 600 °C, the current densities of the cell are 1601, 1458, 1179, and 811 mA / cm 2 , respectively. The test results of the current densities of the cells in each application example and the comparative application example during the electrolysis of water at 650 °C are shown in Table 2.

[0102] For the cell assembled in Application Example 1 during the co - electrolysis of CO2 - H2O, the current density vs. voltage curves at 750 °C, 700 °C, 650 °C, and 600 °C are as Figure 8 shown. It can be obtained from Figure 8 that at 750 °C, 700 °C, 650 °C, and 600 °C, at 1.5 volts, the current densities of the cell are 2238, 1780, 910, and 517 mA / cm 2 , respectively. Generally speaking, the single - cell prepared with the oxygen electrode material of Example 1 achieved excellent current density for the co - electrolysis of CO2 - H2O. Especially at 750 °C and 700 °C, the current densities of the single - cell for the co - electrolysis of CO2 - H2O both exceeded 1500 mA / cm 2 . As the test temperature decreased, the co - electrolysis performance of the cell decreased, indicating that the electrolytic cell with PBSCFNY as the oxygen electrode is suitable for operation at relatively high temperatures. The test results of the current densities of the cells in each application example and the comparative application example during the co - electrolysis of CO2 - H2O at 650 °C are shown in Table 2.

[0103] Table 2 Electrochemical Performance Tests

[0104]

[0105] As can be seen from Table 2, the polarization resistances of the batteries in the application examples of the present invention at 600 °C are all lower than those in the comparative application examples; with the decrease of the polarization resistance, both the peak power density of the fuel cell and the current density of the electrolytic cell show an upward trend. By comparing Table 1 and Table 2, it can be seen that the trend of the thermal expansion coefficient of the oxygen electrode material is consistent with the magnitude of the battery polarization resistance, that is, with the decrease of the thermal expansion coefficient of the oxygen electrode material, the battery polarization resistance continuously decreases. This is because as the thermal expansion coefficient of the oxygen electrode material continuously decreases, it gets closer to the thermal expansion coefficient of the electrolyte BCZYYb, and the contact between the oxygen electrode material and the electrolyte interface in the battery becomes better, thus reducing the polarization resistance of the battery; at the same time, the decrease of the battery polarization resistance makes the peak power density of the battery as a fuel cell and the current density as an electrolytic cell both show an upward trend. Especially, the polarization resistance of the battery in the optimal application example 1 is only 0.57 Ω·cm 2 , and correspondingly, the peak power density of the solid oxide fuel cell at 650 °C is as high as 484 mW / cm 2 , and the current density of the solid oxide electrolytic cell at 650 °C is as high as 1179 mA / cm when electrolyzing H2O 2 , and as high as 910 mA / cm when co-electrolyzing CO2-H2O 2 .

[0106] d) Stability test: The voltage-time curves of the battery assembled in application example 1 and the battery assembled in comparative application example 1 at 650 °C (the hydrogen electrode feed is 97% H2 + 3% H2O) are as Figure 9 shown. As can be seen from Figure 9 , the battery prepared in application example 1 shows better stability and can work stably in the constant potential mode for about 105 hours. In contrast, the battery in comparative application example 1 cannot work properly after 45 hours, and its performance has been gradually decreasing during the stability test.

[0107] In summary, the oxygen electrode material for the proton-conducting reversible solid oxide battery prepared by the present invention has a low thermal expansion coefficient and good matching with the electrolyte BCZYYb; when this oxygen electrode material is used in a solid oxide fuel cell, the battery has a high power density; when this oxygen electrode is used in a solid oxide electrolytic cell, the electrolytic cell has a high current density; and this oxygen electrode has excellent long-term working stability.

Claims

1. An oxygen electrode material for a proton-conducting reversible solid oxide battery, which is a perovskite-type oxide, characterized in that: The chemical formula is Pr z Ba 1-0.5z Sr 1-0.5z Co u Fe 2-u-x-y M x Y y O 5+δ ; Wherein, M is any one of Nb, Ta, Zr, Hf, Mo, and W, 0.05≤x≤0.2, 0.05≤y≤0.15, 0.98≤z≤1.02, 1.48≤u≤1.52, and δ represents a non-stoichiometric oxygen vacancy.

2. The oxygen electrode material for a proton-conducting reversible solid oxide cell according to claim 1, characterized in that: M is Nb or Ta, preferably Nb.

3. The oxygen electrode material for a proton-conducting reversible solid oxide cell according to claim 1, characterized in that: 0.1≤x≤0.15, 0.08≤y≤0.

12.

4. The oxygen electrode material for a proton conducting reversible solid oxide cell according to claim 1, characterized in that: The chemical formula of the oxygen electrode material for the proton-conducting reversible solid oxide battery is PrBa 0.5 Sr 0.5 Co 1.5 Fe 0.3 Nb 0. 1Y 0.1 O 5+δ .

5. The method for preparing the oxygen electrode material for a proton-conducting reversible solid oxide battery according to any one of claims 1 to 4 is a sol-gel method, characterized in that: The following steps are involved: (S1) Press Pr z Ba 1-0.5z Sr 1-0.5z Co u Fe 2-u-x-y M x Y y O 5+δ The chelating agent and metal salts containing Pr, Ba, Sr, Co, Fe, M and Y are dissolved in water in a stoichiometric ratio to form a mixed solution, and then the pH of the mixed solution is adjusted to 7.5-8.5 using a pH regulator, and then heated and evaporated under stirring to obtain a gel; the molar ratio of the chelating agent to the total metal ions is (2-5):1, and the total metal ions are composed of Pr, Ba, Sr, Co, Fe, M and Y ions; (S2) calcining and crushing the gel in an air atmosphere to obtain Pr z Ba 1-0.5z Sr 1-0.5z Co u Fe 2-u-x-y M x Y y O 5+δ Powder, i.e. oxygen electrode material for proton-conducting reversible solid oxide batteries.

6. The preparation method according to claim 5, characterized in that: In step (S1), 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 water, sodium bicarbonate, or triethanolamine.

7. The preparation method according to claim 5, characterized in that: In step (S2), the calcination is performed at 900-1000°C for 2-5 hours; preferably, the calcination is performed by first keeping the temperature at 450-550°C for 0.5-1 hour and then calcining at 950-1000°C for 2-5 hours.

8. The preparation method according to claim 5, characterized in that: In step (S2), the pulverization is air flow pulverization or ball milling, and the Pr z Ba 1-0.5z Sr 1-0.5z Co u Fe 2-u-x-y M x Y y O 5+δ The particle size of the powder is 300-600 mesh.

9. Use of the oxygen electrode material according to any one of claims 1 to 4 in a proton conducting solid oxide fuel cell (P-SOFC) using H2 as fuel.

10. Use of the oxygen electrode material according to any one of claims 1 to 4 in a proton conducting solid oxide electrolysis cell (P-SOEC) for electrolysis of H2O or co-electrolysis of H2O-CO2.

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