High-activity erosion-resistant oxygen electrode and preparation method and application thereof

Abstract

The application belongs to the technical field of solid oxide cells, and provides a high-activity erosion-resistant oxygen electrode as well as a preparation method and application thereof. The oxygen electrode provided by the application takes doped cerium oxide nanoparticles as a shell and takes conductive oxide electrode grains as a core. The mass percentage of the doped cerium oxide nanoparticles in the oxygen electrode is 0.5-8%. The doped cerium oxide nanoparticles are used to coat the conductive oxide main material. While ensuring high activity of the oxygen electrode, the oxygen electrode has the characteristics of stable chemical properties and can effectively inhibit the erosion of water vapor, carbon dioxide and chromium oxide on the oxygen electrode, so that the oxygen electrode shows excellent tolerance. Further, the oxygen electrode is used to prepare a solid oxide cell, which is conducive to ensuring long-term stable operation of the cell under working conditions.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of solid oxide cell, more particularly, to a high-activity and erosion-resistant oxygen electrode, and a preparation method and application thereof. BACKGROUND

[0002] Solid oxide cell is an advanced energy conversion device. In fuel cell mode, solid oxide cell directly converts chemical energy in fuel gas such as hydrogen, carbon monoxide and methane into electrical energy, and generates electricity externally. In electrolysis mode, solid oxide cell can use unstable electrical energy generated by renewable energy such as wind energy and solar energy, or excess electrical energy during idle time of power grid to electrolyze water to produce hydrogen or electrolyze carbon dioxide to produce carbon monoxide, thereby realizing energy storage. The main components of solid oxide cell include oxygen electrode, fuel electrode and electrolyte. Among them, the processes of fuel gas oxidation, water reduction to hydrogen and carbon dioxide reduction to carbon monoxide are carried out in the fuel electrode, while the oxygen electrode is usually exposed to air atmosphere and consumes or generates oxygen according to the operation mode of the cell.

[0003] Under the working conditions of practical application of solid oxide cell, carbon dioxide and moisture in the air can easily erode the oxygen electrode, causing the performance of the cell to decrease and affecting the stability of the cell. In addition, in order to improve the power, a connector is needed to connect multiple single cells in series to form a cell stack. The connector of solid oxide cell is usually made of iron-chromium alloy material or nickel-chromium alloy material, such as Fe-10Cr, SUS 430, AL 453, Inconel 600 and ASL 528. Under the working conditions (700-900℃), chromium in the iron-chromium alloy connector is oxidized to gaseous chromium oxide (CrO3) at the end of the oxygen electrode and diffuses into the electrode atmosphere. Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O3, Ba 0.9 Co 0.7 Fe 0.2 Nb 0.1 O3 and SrCo 0.7 Fe 0.2 Nb 0.1 O3, etc. have excellent electrochemical performance and catalytic activity, which enables the cell to perform excellent performance at low temperature below 650℃. However, under the working conditions, the alkaline earth metal ions are easily reacted with impurities such as water, carbon dioxide and chromium oxide in the working atmosphere, thereby being poisoned and failed, causing the performance of the cell to degrade. La 0.6 Sr 0.4 FeO3, La 0.8 Sr 0.2 MnO3 and LaNi 0.6 Fe 0.4The traditional oxygen electrode material represented by O3 often exhibits good stability, but its ion-electron mixed conductivity and catalytic activity are relatively low, which is difficult to be used in the medium and low temperature solid oxide battery operating at 500-800 DEG C. The cerium oxide doped with heterovalent metal ions, such as gadolinium oxide doped cerium oxide, samarium oxide doped cerium oxide, lanthanum oxide doped cerium oxide and the like, exhibits good oxygen ion conductivity and chemical stability, but the oxygen exchange reaction catalytic activity of cerium oxide is low in the oxygen atmosphere, and it cannot be directly used as an oxygen electrode material. From the above, the solid oxide battery composed of the above-mentioned materials is difficult to operate stably for a long time under the working conditions.

[0004] Therefore, it is urgent to develop an oxygen electrode with good stability, high conductivity and catalytic activity, and erosion resistance, which can further prepare a solid oxide battery with high performance and long-term stable operation under working conditions. SUMMARY

[0005] The present application aims to at least solve one of the above-mentioned technical problems in the prior art. To this end, the present application proposes a high-activity erosion-resistant oxygen electrode and its preparation method and application. The oxygen electrode provided by the present application has good stability, high conductivity and catalytic activity, and is erosion-resistant, and is further used to prepare a solid oxide battery, which can maintain high performance and operate stably for a long time under working conditions.

[0006] The first aspect of the present application provides a high-activity erosion-resistant oxygen electrode.

[0007] Specifically, a high-activity erosion-resistant oxygen electrode, the oxygen electrode is a core-shell structure, the core is a conductive oxide electrode grain, and the shell is a doped cerium oxide nanoparticle, and the mass percentage of the doped cerium oxide nanoparticle in the oxygen electrode is 0.5-8%.

[0008] The composite oxygen electrode with core-shell structure provided by the present application uses doped cerium oxide nanoparticles as a coating phase (shell) and conductive oxide electrode grains as a main phase (core). The doped cerium oxide nanoparticles are used to coat the conductive oxide electrode grains, which can ensure high activity of the oxygen electrode, impart high chemical stability to the oxygen electrode, effectively inhibit the erosion of water vapor, carbon dioxide and chromium oxide on the oxygen electrode, and make the oxygen electrode exhibit excellent resistance. Further using the oxygen electrode to prepare a solid oxide battery is conducive to ensuring the long-term stable operation of the battery under working conditions. In summary, the present application combines the advantages of doped cerium oxide nanoparticles with high chemical stability and conductive oxides with high activity, while effectively avoiding the disadvantages of each material, and exhibits high activity and resistance to air impurities.

[0009] Preferably, the mass percentage of the doped cerium oxide nanoparticle in the oxygen electrode is 1-5%.

[0010] Preferably, the particle size of the conductive oxide electrode grains is 200-400 nm. The electrode grains with small particle size are beneficial to the atomization of the slurry and the coating.

[0011] Preferably, the conductive oxide electrode grains are perovskite conductive oxides.

[0012] Further preferably, the conductive oxide electrode grains are Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O3, Ba 0.9 Co 0.7 Fe 0.2 Nb 0.1 O3 (referred to as BCFN), La 0.6 Sr 0.4 CoO3. These materials have the characteristics of high activity, and exhibit excellent ion conductivity, electronic conductivity and catalytic activity in air or oxygen atmosphere.

[0013] Preferably, the doped cerium oxide nanoparticles (shell) are doped rare metal oxide cerium oxide nanoparticles. The doped rare metal oxide cerium oxide nanoparticles are obtained by doping cerium oxide nanoparticles with rare metal oxides.

[0014] Further preferably, the doped cerium oxide nanoparticles (shell) are at least one of doped gadolinium oxide cerium oxide nanoparticles, doped samarium oxide cerium oxide nanoparticles, and doped lanthanum oxide cerium oxide nanoparticles.

[0015] More preferably, the doped cerium oxide nanoparticles (shell) are doped gadolinium oxide cerium oxide nanoparticles (Ce 0.8 Gd 0.2 O 1.9 , referred to as GDC).

[0016] Preferably, the molar amount of rare metal elements in the doped cerium oxide nanoparticles accounts for 5-25% of the total molar amount of metal elements, and the total molar amount of metal elements is the sum of the molar amounts of all metal elements in the doped cerium oxide nanoparticles.

[0017] The second aspect of the present application provides a preparation method of a high-activity erosion-resistant oxygen electrode.

[0018] The preparation method of a high-activity erosion-resistant oxygen electrode comprises the following steps:

[0019] The conductive oxide electrode grain (core) and the doped cerium oxide nanoparticle (shell) precursor solution are mixed to prepare a mixed slurry, which is then dried to prepare a precursor coated powder, followed by a first calcination to obtain a composite electrode powder, and then the composite electrode powder and battery glue are mixed to prepare an electrode slurry, followed by a second calcination to obtain the oxygen electrode.

[0020] The preparation method of the oxygen electrode provided by the application is efficient, low in cost and widely applicable.

[0021] Preferably, the mass-volume concentration of the solute of the doped cerium oxide nanoparticle precursor solution is 10-60 mg / mL.

[0022] Preferably, the raw materials for preparing the doped cerium oxide nanoparticles include a cerium salt (such as Ce(NO3)4) and a doped metal salt.

[0023] Preferably, the doped metal salt is at least one of Gd(NO3)3, La2(CO3)3, BaCO3, SrCO3, Co2O3, Fe2O3 and Nb2O5.

[0024] Preferably, the preparation method of the doped cerium oxide nanoparticle precursor solution comprises the following steps: mixing the raw materials for preparing the doped cerium oxide nanoparticles, dissolving them in water to obtain a precursor salt-water precursor solution, and then dissolving them in ethanol to obtain a salt-water-ethanol precursor solution, thereby obtaining the doped cerium oxide nanoparticle precursor solution.

[0025] Preferably, the volume ratio of the precursor salt-water precursor solution to ethanol is 1:(20-80).

[0026] Preferably, after the raw materials for preparing the conductive oxide electrode grain and the doped cerium oxide nanoparticles are mixed, ball milling is performed to prepare the mixed slurry.

[0027] Further preferably, after the conductive oxide electrode grain (core) and the doped cerium oxide nanoparticle precursor solution are mixed, the mixture is placed in a ball milling tank, and ball milling beads with the same mass as the conductive oxide electrode grain are added, and the ball milling is performed at a rotation speed of 300-600 rpm for 12-36 h to prepare the mixed slurry.

[0028] Preferably, the raw materials for preparing the battery glue include ethyl cellulose and rosin alcohol.

[0029] Preferably, the preparation method of the battery glue comprises dissolving ethyl cellulose in rosin alcohol to prepare the battery glue.

[0030] Further preferably, the preparation method of the battery glue comprises: dissolving ethyl cellulose in abietinol under the condition of water bath heating at 50-80℃, wherein the mass fraction of ethyl cellulose in the battery glue is 5-20%, and stirring is carried out at a speed of 300-600 rpm, and after complete dissolution, standing and cooling to 20-30℃.

[0031] Preferably, the drying is spray drying. By using spray drying, the mixed slurry is atomized in hot air, and at the same time, the solvent (water and ethanol) is removed, to obtain the precursor coated powder.

[0032] Preferably, the spray gun pressure of the spray drying is 1.5-4 bar, and / or the hot air temperature of the spray drying is 30-100℃.

[0033] Further preferably, the spray gun pressure of the spray drying is 2-4 bar, and / or the hot air temperature of the spray drying is 70-90℃.

[0034] Preferably, after the electrode slurry is prepared, the electrode slurry is then printed onto a solid oxide electrolyte substrate by silk screen printing, and then a second calcination is carried out to prepare the oxygen electrode.

[0035] Preferably, the temperature of the first calcination is 500-700℃, and / or the time of the first calcination is 0.5-2h.

[0036] Further preferably, the temperature of the first calcination is 600-650℃, and / or the time of the first calcination is 1-1.5h.

[0037] Preferably, the temperature of the second calcination is 850-1200℃, and / or the time of the second calcination is 1-4h.

[0038] Further preferably, the temperature of the second calcination is 850-1150℃, and / or the time of the second calcination is 2-2.5h.

[0039] In the first calcination process, the precursor reacts to generate conductive oxide electrode grains, and at the same time, the doped cerium oxide nanoparticles are coated in the form of nanoparticles.

[0040] Preferably, after the calcination, a block is obtained, the block is crushed to obtain a powder, the powder is ball milled at least twice, and then the drying and calcination are repeatedly carried out again to prepare the oxygen electrode.

[0041] The third aspect of the present application provides a use of a high-activity erosion-resistant oxygen electrode.

[0042] A use of a high-activity erosion-resistant oxygen electrode in the preparation of a battery.

[0043] Preferably, the battery is a solid oxide battery.

[0044] A fourth aspect of the present application provides a solid oxide battery.

[0045] A solid oxide battery comprising the high-activity erosion-resistant oxygen electrode, a fuel electrode and an electrolyte.

[0046] Preferably, the electrolyte is at least one of lanthanum strontium gallium magnesium (LSGM), yttrium stabilized zirconia (YSZ), scandium stabilized zirconia (ScSZ), samarium doped ceria (SDC), barium zirconium yttrium (BZY) and barium cerium zirconium yttrium ytterbium (BZCYYb).

[0047] Preferably, the fuel electrode is at least one of nickel oxide mixed YSZ (Ni-YSZ), nickel oxide mixed GDC (Ni-GDC) and lanthanum strontium chromium iron (LSCrF).

[0048] Compared with the prior art, the present application has the following beneficial effects:

[0049] The oxygen electrode provided by the present application uses doped ceria nanoparticles as a shell and conductive oxide electrode grains as a core, wherein the mass percentage of the doped ceria nanoparticles in the oxygen electrode is 0.5-8%. The doped ceria nanoparticles are used to coat the main body material of the conductive oxide electrode grains, which not only ensures the high activity of the oxygen electrode, but also endows the oxygen electrode with the characteristics of stable chemical properties, effectively inhibits the erosion of water vapor, carbon dioxide and chromium oxide on the oxygen electrode, and makes the oxygen electrode exhibit excellent resistance. Further, the oxygen electrode of the present application is used to prepare a solid oxide battery, which is conducive to ensuring the high performance and long-term stable operation of the battery under working conditions. BRIEF DESCRIPTION OF DRAWINGS

[0050] Figure 1 A scanning electron microscope (SEM) comparison chart of the BCFN oxygen electrode prepared for Comparative Example 1 and the GDC@BCFN oxygen electrode prepared for Example 1;

[0051] Figure 2 A schematic diagram of the operation process of the oxygen electrode of Example 1;

[0052] Figure 3 A schematic diagram of the operation process of the oxygen electrode of Comparative Example 1;

[0053] Figure 4 A polarization impedance chart of the 5% GDC@BCFN oxygen electrode of Example 1 operated in 650℃ air with water content of 3% and carbon dioxide content of 5% for 20h;

[0054] Figure 5Polarization impedance variation chart of the oxygen electrode of Comparative Example 1 operated in air with water content of 3% and carbon dioxide content of 5% for 20h at 650℃;

[0055] Figure 6 SEM comparison chart of the BCFN oxygen electrode prepared for Comparative Example 1 and the GDC@BCFN oxygen electrode prepared for Example 1 after operation in air with water content of 3% and carbon dioxide content of 5%;

[0056] Figure 7 Polarization impedance chart of the oxygen electrode of Example 1 operated at 800℃ with ferrochrome alloy as the connecting body;

[0057] Figure 8 Polarization impedance chart of the oxygen electrode of Comparative Example 1 operated at 800℃ with ferrochrome alloy as the connecting body;

[0058] Figure 9 Stability chart of the oxygen electrodes of Examples 1-3 and Comparative Example 1 under the condition of 800℃ with ferrochrome alloy as the connecting body;

[0059] Figure 10 Polarization impedance chart of the oxygen electrodes of Example 1, Comparative Example 1 and Comparative Example 2;

[0060] Figure 11 Performance test result chart of the oxygen electrodes of Comparative Example 1, Example 2, Example 3, Example 1 and Comparative Example 3 in air atmosphere at 800℃. DETAILED DESCRIPTION

[0061] In order to make the skilled in the art more clearly understand the technical solutions described in the present application, the following examples are listed for illustration. It should be pointed out that the following examples do not constitute a limitation on the scope of protection required by the present application.

[0062] The raw materials, reagents or devices used in the following examples, if not specifically stated, can be obtained from conventional commercial channels, or can be obtained by existing known methods.

[0063] The preparation method of BCFN used in the present application comprises the following steps:

[0064] The precursor powder and the solvent are mixed, and ball milling is carried out by adding ball milling beads with the same mass as the precursor powder, the rotation speed is 400r / min, the ball milling time is 24h, the mixed slurry is prepared, dried at 80℃ for 24h, the mixed powder is prepared, calcined at 1100℃ for 12h, crushed, and the powder is obtained, and then the above steps are repeated again to prepare the BCFN.

[0065] The precursor powder comprises BaCO3, Co2O3, Fe2O3, Nb2O5, and the molar ratio is 9:3.5:1:0.5.

[0066] Example 1

[0067] A high-activity erosion-resistant oxygen electrode (referred to as GDC@BCFN or 5% GDC@BCFN) is a core-shell structure; the core is an electron-ion mixed conductor oxide electrode grain BCFN with a particle size of about 300 nm; the shell is gadolinium oxide doped cerium oxide nanoparticles GDC, wherein the molar amount of gadolinium (Gd) accounts for 20% of the total molar amount of metal elements in GDC; in the oxygen electrode, the mass percentage of GDC is 5wt%.

[0068] A preparation method of 5% GDC@BCFN, comprising the following steps:

[0069] (1) According to the chemical mass ratio of Ce and Gd in GDC, Ce(NO3)4 and Gd(NO3)3 are weighed and mixed, completely dissolved in deionized water, and prepared into a 30mg / mL nitrate aqueous solution;

[0070] (2) The nitrate aqueous solution is added to anhydrous ethanol for complete mixing, wherein the volume ratio of the nitrate aqueous solution to anhydrous ethanol is 1:50, and a nitrate-water-ethanol precursor solution is prepared;

[0071] (3) The mass of BCFN is calculated according to 5% GDC@BCFN and weighed, poured into the nitrate-water-ethanol precursor solution, and ball milled at a speed of 450 rpm for 24h with ball milling beads of the same mass as BCFN, to prepare a precursor-BCFN mixed slurry;

[0072] (4) A spray dryer is used to spray the mixed slurry at a pressure of 2bar, and the mixed slurry is atomized in hot air at 80℃. After the volatilization of ethanol and water, a powder coated with a nitrate precursor is prepared. Then the coated powder is collected and subjected to a first calcination at 600℃ for 1h, and the precursor reacts to form GDC, to prepare a 5% GDC@BCFN electrode powder;

[0073] (5) Ethyl cellulose and terpineol are mixed, and the ethyl cellulose is completely dissolved in terpineol by heating and stirring to prepare a battery glue; wherein the mass percentage of ethyl cellulose in the battery glue is 6wt%;

[0074] (6) The 5% GDC@BCFN electrode powder is mixed with the electrode glue to prepare an electrode slurry, which is screen printed on an LSGM solid oxide electrolyte, and then subjected to a second calcination at 1000℃ for 2h to prepare a 5% GDC@BCFN oxygen electrode.

[0075] Example 2

[0076] A high-activity and erosion-resistant oxygen electrode (referred to as 1% GDC@BCFN), which is different from Example 1 in that the mass percentage of GDC in the oxygen electrode is replaced by 1wt%.

[0077] Example 3

[0078] A high-activity and erosion-resistant oxygen electrode (referred to as 3% GDC@BCFN), which is different from Example 1 in that the mass percentage of GDC in the oxygen electrode is replaced by 3wt%.

[0079] Comparative Example 1 (BCFN alone)

[0080] An oxygen electrode, which is different from Example 1 in that the BCFN alone (without GDC), and the mass of the oxygen electrode of Comparative Example 1 is equal to the mass of the 5% GDC@BCFN oxygen electrode finally prepared in Example 1.

[0081] Comparative Example 2 (direct mixing preparation method)

[0082] An oxygen electrode (referred to as BCFN-5%GDC), which is different from Example 1 in that the preparation method is changed to: uniformly mixing GDC powder and BCFN powder to obtain BCFN-5%GDC electrode grains. The remaining steps are the same as those of Example 1.

[0083] Comparative Example 3 (increasing the proportion of GDC)

[0084] A high-activity and erosion-resistant oxygen electrode (referred to as 10% GDC@BCFN), which is different from Example 1 in that the mass percentage of GDC in the oxygen electrode is replaced by 10%.

[0085] Product effect test

[0086] 1. Micro-morphology

[0087] The micro-morphologies of the BCFN oxygen electrode of Comparative Example 1 and the GDC@BCFN oxygen electrode prepared in Example 1 are shown in Figure 1 A, Figure 1 B, respectively. By comparison, it can be seen that the oxygen electrode of Example 1 contains GDC nanoparticles and is coated on the surface of the BCFN grain.

[0088] 2. Electrochemical performance test of the oxygen electrode (resistance test of the oxygen electrode to water and carbon dioxide)

[0089] As shown in Figure 2 , the coated high-activity and erosion-resistant oxygen electrode prepared in Example 1 has a conductive oxide electrode grain (core) coated with doped cerium oxide nanoparticles (shell), which can effectively inhibit the erosion of CO2, H2O and CrO3 to the oxygen electrode under working conditions, while maintaining the high activity of the conductive oxide electrode grain (core).

[0090] As shown in Figure 3 , the BCFN oxygen electrode of Comparative Example 1 is a traditional solid oxide oxygen electrode, and the surface of which is not coated with doped ceria nanoparticles (shell), so it is difficult to inhibit the corrosion of CO2, H2O and CrO3 to the oxygen electrode.

[0091] The electrochemical performance of the oxygen electrode can be indicated by its polarization impedance, the greater the polarization impedance, the slower the oxygen exchange reaction rate in the oxygen electrode, and the worse the electrode performance. The resistance test of the oxygen electrode of Example 1 and Comparative Example 1 was carried out, and the polarization impedance was as follows:

[0092] As shown in Figure 4 , the 5% GDC@BCFN oxygen electrode of Example 1 was operated in air with water content of 3% and carbon dioxide content of 5% at 650℃ for 20h, and the polarization impedance did not change significantly. The test results of Comparative Example 1 are shown in Figure 5 , the uncoated BCFN oxygen electrode significantly increased in polarization impedance during the operation process of 20h in air with water content of 3% and carbon dioxide content of 5% at 650℃, and the electrode performance deteriorated. Among them, Figure 4 and Figure 5 Beginning is the initial operation condition, 1 hour is the condition after 1 hour of operation, 20 hours is the condition after 20 hours of operation, Z' is the real part of impedance, and -Z" is the imaginary part of impedance.

[0093] The performance test results of the oxygen electrode of Example 1 and Comparative Example 1 are summarized in Table 1.

[0094] Table 1 Polarization impedance (unit: ohm*cm 2 ) change of the oxygen electrode of Example 1 and Comparative Example 1 operated in air with water content of 3% and carbon dioxide content of 5% at 650℃ for different time

[0095] Start 1h 20h Example 1 0.08 0.11 0.15 Comparative Example 1 0.08 0.25 0.69

[0096] As can be seen from Table 1, under the same conditions, after 20h of operation, the polarization impedance of Comparative Example 1 increased to 0.69 ohm*cm 2 , while that of Example 1 only slightly increased to 0.15 ohm*cm 2 , still maintained around the initial polarization impedance, indicating that the oxygen electrode of Example 1 coated with 5% GDC nanoparticles is beneficial to maintaining the activity of alkaline earth metal-based electrode, while significantly improving the resistance of the oxygen electrode to water and carbon dioxide.

[0097] The micro-morphology of the oxygen electrode of Example 1 and Comparative Example 1 after operation in air with water content of 3% and carbon dioxide content of 5% is respectively as shown in Figure 6 A, Figure 6As shown in FIG. B, by comparison, it can be seen that under the same working conditions, H2O and CO2 in the air erode the oxygen electrode of Comparative Example 1 by reacting with BCFN, while the GDC nanoparticles in the oxygen electrode of Example 1 can effectively inhibit the erosion process, and the morphology of the oxygen electrode changes little before and after operation of the oxygen cell.

[0098] 3. Stability test of the oxygen electrode (chromium corrosion resistance test)

[0099] The oxygen electrodes of Example 1 and Comparative Example 1 were respectively connected with a chromium-iron alloy at 800°C, and the change in polarization impedance during 96h of operation was recorded. As shown in FIG. C, Figure 7 , the polarization impedance of the 5% GDC@BCFN of Example 1 did not change significantly during operation, indicating that its electrochemical properties were stable. As shown in FIG. D, Figure 8 , the polarization impedance of the BCFN of Comparative Example 1 increased significantly during operation, indicating that its electrochemical properties were poor in stability. The chromium corrosion resistance of the oxygen electrodes of Example 1 and Comparative Example 1 was compared, and the results are summarized in Table 2.

[0100] Table 2 Change in polarization impedance (unit: ohm*cm 2 ) of the oxygen electrodes of Example 1 and Comparative Example 1 at 800°C, 5% GDC@BCFN and BCFN, with a chromium-iron alloy as the connecting body

[0101] Start 48h 96h Example 1 0.015 0.019 0.023 Comparative Example 1 0.022 0.041 0.065

[0102] As can be seen from Table 2, after 96h of operation, the polarization impedance of the oxygen electrode of Example 1 increased from 0.015 to 0.023 ohm*cm 2 , with an increase rate of 8.54×10 -5 ohm*cm 2 / h; while the polarization impedance of the oxygen electrode of Comparative Example 1 increased from 0.022 to 0.065 ohm*cm 2 , with an increase rate of 4.48×10 -4 ohm*cm 2 / h, which indicates that the 5% GDC@BCFN coated with GDC nanoparticles can effectively reduce the polarization impedance increase rate by an order of magnitude, indicating that the 5% GDC@BCFN oxygen electrode has high performance and excellent chromium corrosion resistance.

[0103] The operation process of the oxygen electrodes of Comparative Example 1 and Examples 1-3 with different GDC coating amounts at 800°C with a chromium-iron alloy as the connecting body was compared, and the results are shown in FIG. E, Figure 9 , which indicates that the GDC in the form of nanoparticles can maintain the high performance of the alkaline earth metal-based electrode, and the addition of a small amount (1%) of GDC can significantly improve the corrosion resistance of the electrode. With the increase of the content of GDC, the GDC@BCFN becomes more stable. Among them,Figure 9 Time is running time, and Resistance is resistance.

[0104] 4. Performance comparison of oxygen electrodes (BCFN, 5% GDC@BCFN, BCFN-5% GDC) of Comparative Example 1, Example 1 and Comparative Example 2

[0105] The performance test results of the three oxygen electrodes (BCFN, 5% GDC@BCFN, BCFN-5% GDC) obtained by different preparation methods at 800°C in an air atmosphere are shown in Table 1. Figure 10 The polarization resistances of the three are 0.022, 0.0156 and 0.046 ohm*cm, respectively. 2 It can be seen from the results that, compared with Comparative Example 1, the addition of GDC to the BCFN-5% GDC composite electrode prepared by the traditional mechanical mixing method of Comparative Example 2 actually reduces the electrode performance, while the GDC@BCFN prepared by the method of Example 1 can improve the excellent performance of the electrode material.

[0106] 5. Performance comparison of oxygen electrodes (BCFN, 1% GDC@BCFN, 3% GDC@BCFN, 5% GDC@BCFN, 10% GDC@BCFN) of Comparative Example 1, Example 2, Example 3, Example 1 and Comparative Example 3

[0107] The performance test results of the five oxygen electrodes (BCFN, 1% GDC@BCFN, 3% GDC@BCFN, 5% GDC@BCFN, 10% GDC@BCFN) obtained by the same preparation method but different coating amounts at 800°C in an air atmosphere are shown in Table 2. Figure 11 The polarization resistances of the above five oxygen electrodes are 0.022, 0.021, 0.015, 0.0156 and 0.045 ohm*cm, respectively. 2 It can be seen from the results that, compared with Comparative Example 1, the 1%, 3%, 5% GDC nanoparticle coated BCFN grains prepared in Examples 1-3 can all improve the performance of the oxygen electrode, but the excessive GDC (10%) in Comparative Example 3 actually increases the polarization resistance and leads to poor electrode performance.

Claims

1. An oxygen electrode characterized in that, The oxygen electrode is a core-shell structure, the core is a conductive oxide electrode grain, the conductive oxide electrode grain is Ba 0.9 Co 0.7 Fe 0.2 Nb 0.1 O3, the shell is a doped cerium oxide nanoparticle, the doped cerium oxide nanoparticle is a gadolinium-doped oxide nanoparticle, and the mass percentage of the doped cerium oxide nanoparticle in the oxygen electrode is 3-5%. The oxygen electrode is prepared by a preparation method comprising the following steps: According to the chemical mass ratio of Ce and Gd in the GDC, Ce(NO3)4 and Gd(NO3)3 are weighed and mixed, and completely dissolved in deionized water to prepare a 30 mg / mL nitrate aqueous solution; the nitrate aqueous solution is added to anhydrous ethanol for complete mixing, wherein the volume ratio of the nitrate aqueous solution to the anhydrous ethanol is 1:50, to prepare a nitrate-water-ethanol precursor solution; The conductive oxide electrode grains and the nitrate-water-ethanol precursor solution are ball-mixed to prepare a mixed slurry, which is then dried to prepare a precursor-coated powder, followed by first calcination to obtain a composite electrode powder, and then the composite electrode powder and battery glue are mixed to prepare an electrode slurry, followed by second calcination to prepare the oxygen electrode.

2. The oxygen electrode of claim 1, wherein The particle size of the conductive oxide electrode grains is 200-400 nm.

3. The oxygen electrode of claim 1, wherein The molar amount of gadolinium metal elements in the doped cerium oxide nanoparticles accounts for 5-25% of the total molar amount of metal elements, and the total molar amount of metal elements is the sum of the molar amounts of all metal elements in the doped cerium oxide nanoparticles.

4. A method of making an oxygen electrode, characterized by, comprising the following steps: According to the chemical mass ratio of Ce and Gd in the GDC, Ce(NO3)4 and Gd(NO3)3 are weighed and mixed, and completely dissolved in deionized water to prepare a 30 mg / mL nitrate aqueous solution; the nitrate aqueous solution is added to anhydrous ethanol for complete mixing, wherein the volume ratio of the nitrate aqueous solution to the anhydrous ethanol is 1:50, to prepare a nitrate-water-ethanol precursor solution; The conductive oxide electrode grains and the nitrate-water-ethanol precursor solution are ball-mixed to prepare a mixed slurry, which is then dried to prepare a precursor-coated powder, followed by first calcination to obtain a composite electrode powder, and then the composite electrode powder and battery glue are mixed to prepare an electrode slurry, followed by second calcination to prepare the oxygen electrode. The oxygen electrode is a core-shell structure, the core is a conductive oxide electrode grain, the conductive oxide electrode grain is Ba 0.9 Co 0.7 Fe 0.2 Nb 0.1 O3, the shell is a doped cerium oxide nanoparticle, the doped cerium oxide nanoparticle is a gadolinium-doped oxide nanoparticle, and the mass percentage of the doped cerium oxide nanoparticle in the oxygen electrode is 3-5%.

5. Use of the oxygen electrode of any one of claims 1-3 or prepared by the preparation method of claim 4 in the preparation of a battery.

6. A solid oxide cell characterized by, The battery comprises the oxygen electrode of any one of claims 1-3 or prepared by the preparation method of claim 4, a fuel electrode, and an electrolyte.

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