Solid oxide battery bifunctional electrode material, preparation method and application

Abstract

This invention discloses a solid oxide bifunctional electrode material for batteries, its preparation method, and its application, belonging to the field of fuel cell materials technology. The chemical formula of the solid oxide bifunctional electrode material is NdBaCo. 2–x Zr x O 5+δ The x-value is 0.04~0.12. According to NdBaCo... 2–x Zr x O 5+δ In a stoichiometric ratio, neodymium, barium, cobalt, and zirconium sources were added to a nitric acid solution, followed by the addition of citric acid and EDTA to form a mixed solution. The solution was heated and stirred to form a gel. When the gel volume expanded to 2.5–3.5 times the volume of the nitric acid solution, it was dried to obtain a dry gel, which was then calcined at 400–900°C for 10 hours. The calcined solid was then ground with alcohol for 2 hours and sintered in air at 1000–1200°C for 10 hours to obtain a solid oxide battery bifunctional electrode material. The introduction of Zr in this invention can suppress Ba... 2+ Surface segregation and cation defects generate more oxygen vacancies, which enhance ORR reactivity and CO2 tolerance.

Description

Technical Field

[0001] This invention belongs to the field of fuel cell materials technology, specifically relating to a solid oxide battery bifunctional electrode material, its preparation method, and its application. Background Technology

[0002] Energy is the core foundation supporting global socio-economic development. Currently, the world's energy consumption structure is still dominated by fossil fuels (coal, oil, and natural gas), accounting for over 80%. Coal will remain a major energy source for a considerable period, and coal-fired power, as the most important form of coal utilization, accounts for a significant proportion of electricity supply. However, traditional fossil fuel utilization methods suffer from low energy conversion efficiency and high levels of pollutants (CO2, SO2, SO2). x NO x Large emissions not only waste energy but also exacerbate global warming and environmental pollution. Therefore, developing efficient, clean, and low-carbon energy conversion technologies has become a critical issue urgently needing to be addressed in the energy sector. Solid oxide fuel cells (SOFCs), as an advanced electrochemical energy conversion device, have become a research hotspot in new energy technologies due to their significant advantages, such as high energy conversion efficiency, strong fuel adaptability, and environmental friendliness. The performance of SOFCs largely depends on their cathode materials, which typically require high oxygen reduction reaction activity, good electronic conductivity, and chemical stability. Double perovskite oxide LnBaCo2O 5+δ As a candidate cathode material, it has high electrical conductivity, oxygen surface exchange coefficient and bulk diffusion coefficient. Its high oxygen reduction reaction activity and good electrical conductivity have been extensively studied in SOFC.

[0003] Unfortunately, the performance of layered double perovskite air electrodes deteriorates significantly due to surface cation segregation during long-term operation, posing a serious challenge to their practical applications. Therefore, developing high-performance and highly stable fuel cell electrode materials is of paramount importance. Summary of the Invention

[0004] To address the problem of reduced activity and stability caused by cation segregation in layered perovskite electrodes in existing technologies, this invention provides a bifunctional electrode material for solid oxide batteries, its preparation method, and its application. The introduction of Zr can suppress Ba... 2+ Surface segregation, cation defects generate more oxygen vacancies, enhancing ORR reactivity, Ba 2+ and Zr 4+ It combines the inhibition of surface carbonate formation to enhance CO2 tolerance.

[0005] This invention is achieved through the following technical solution: In a first aspect, the present invention provides a solid oxide battery bifunctional electrode material, wherein the chemical formula of the solid oxide battery bifunctional electrode material is NdBaCo. 2–x Zr x O 5+δ The value of x is 0.04~0.12.

[0006] Furthermore, the chemical formula of the solid oxide battery bifunctional electrode material is NdBaCo. 1.92 Zr 0.08 O 5+δ .

[0007] In a second aspect, the present invention provides a method for preparing the aforementioned solid oxide battery bifunctional electrode material, comprising the following steps: (1) According to NdBaCo 2–x Zr x O 5+δ According to the stoichiometric ratio, neodymium source, barium source, cobalt source and zirconium source are added to nitric acid solution, and then citric acid and EDTA are added to form a mixed solution; (2) The mixed solution in step (1) is adjusted to pH 7-8 with ammonia water, heated and stirred to form a gel. When the volume of the gel expands to 2.5-3.5 times the volume of the nitric acid solution, it is dried to obtain dry gel. (3) The dry adhesive in step (2) is calcined at 400~900℃ for 5~10h; (4) The solid after calcination in step (3) is ground with alcohol for 2 hours and sintered in air at 1000~1200℃ for 10 hours to obtain a solid oxide battery bifunctional electrode material.

[0008] Further, in step (1), the neodymium source is Nd(NO3)3·6H2O, the barium source is C4H6BaO4, the cobalt source is Co(NO3)2·6H2O, and the zirconium source is Zr(NO3)4·5H2O; the nitric acid solution is a nitric acid solution prepared by adding 2~5g of concentrated nitric acid to every 100mL of water.

[0009] Furthermore, in step (1), the total metal ions of neodymium source, barium source, cobalt source and zirconium source are in a molar ratio of 1:1~2:0.5~1 to citric acid and EDTA.

[0010] Furthermore, the heating and stirring conditions in step (2) are 80~100℃ for 5~8h.

[0011] Furthermore, the drying conditions in step (2) are baking at 150~180℃ in a drying oven for 5~10 h.

[0012] In a third aspect, the present invention provides the application of the aforementioned solid oxide battery bifunctional electrode material in the preparation of solid fuel cells.

[0013] Furthermore, the aforementioned solid oxide battery bifunctional electrode material serves as the cathode material for a solid fuel cell.

[0014] Furthermore, the specific applications include: 1) NdBaCo 2–x Zr x O 5+δ Electrode materials are mixed with organic binders to form a uniformly mixed slurry, which serves as the electrode slurry. 2) Coating electrode paste onto an oxygen ion-conducting, anode-supported solid oxide cell (GDC) with... 0.9 Gd 0.1 O 1.95 A single cell with the structure NdBaCo was obtained by calcining the surface of the cell at 1000°C for 3 h in air. 2–x Zr x O 5+δ |GDC|YSZ(Y2O3-stabilized zirconia)|NiO-YSZ; 3) Coating electrode paste onto a proton-conducting, anode-supported solid oxide cell BZCYYb(BaZr) 0.1 Ce 0.7 Y 0.1 Yb 0.1 O 3–δ A single cell with the structure NdBaCo was obtained by calcining the surface of the cell at 1000℃ for 3 h in air. 2– x Zr x O 5+δ |BZCYYb|NiO-BZCYYb.

[0015] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: 1. This invention employs a one-pot method to prepare NdBaCo nanoparticles with heterostructured BaZrO3. 2– x Zr x O 5+δ The material is a new type of solid oxide battery electrode material, characterized by its simple and uniform composition and relatively simple synthesis process.

[0016] 2. The NdBaCo prepared by this invention 2–x Zr x O 5+δ In this material, the introduction of Zr can suppress Ba. 2+Surface segregation, cation defects generate more oxygen vacancies, enhancing ORR reactivity, Ba 2+ and Zr 4+ It combines the inhibition of surface carbonate formation to enhance CO2 tolerance.

[0017] 3. The cathode material prepared by this invention can be used not only in oxygen ion conduction system batteries, but also in proton transport system batteries. Thanks to the presence of BaZrO3 heterostructure nanoparticles, proton transport is facilitated. Attached Figure Description

[0018] Figure 1 X-ray diffraction patterns of NBC@Z4, NBC@Z8, NBC@Z12, and NBC are shown, where (a) is the overall pattern and (b) is a magnified view of a part. Figure 2 The thermal expansion curves and electrical conductivity curves of NBC@Z8 and NBC are shown, where (a) is the thermal expansion coefficient curve and (b) is the electrical conductivity curve. Figure 3 The following are electrochemical performance test results for bifunctional electrode materials in solid oxide batteries: (a) typical impedance spectrum of NBC oxygen electrode, (b) typical impedance spectrum of NBC@Z4 oxygen electrode, (c) typical impedance spectrum of NBC@Z8 oxygen electrode, (d) typical impedance spectrum of NBC@Z12 oxygen electrode, (e) active surface area (ASR) value, (f) Arrhenius plot, (g) typical impedance spectrum of NBC cathode at different oxygen partial pressure (Po2) levels at 700℃, and (h) typical impedance spectrum of NBC@Z8 cathode at different Po2 levels at 700℃. Figure 4 The current-voltage characteristics and output power density curves of single cells of cathode NBC and NBC@Z8 are shown. (a) is NBC, and (b) is NBC@Z8(b). Figure 5 Impedance variation diagrams of NBC and NBC@Z8 symmetrical cells at different moisture pressures at 650 °C, (a) for NBC, (b) for NBC@Z8; Figure 6 The current-voltage characteristics and output power density curves of a single cell (NiO-BZCYYb|BZCYYb|cathode) are shown in (a) with NBC as the cathode and (b) with NBC@Z8 as the cathode. Detailed Implementation

[0019] The present invention is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods not specifically described in the following examples are generally performed under conventional conditions or as recommended by the manufacturer.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of skill in the art. All reagents and materials used in this invention are readily available through conventional means, and unless otherwise specified, they shall be used in accordance with conventional methods in the art or as per the product instructions.

[0021] Example 1 (1) According to 10g NdBaCo 1.96 Zr 0.04 O 5+δ To achieve the desired stoichiometric ratio, Nd(NO3)3·6H2O, C4H6BaO4, Co(NO3)2·6H2O, and Zr(NO3)4·5H2O were added to a nitric acid solution (5g of concentrated nitric acid was added to 100mL of deionized water). Then, citric acid (C6H8O7·H2O) and EDTA were added to make the molar ratio of total metal cations, citric acid, and EDTA 1:1:0.8, forming a mixed solution. (2) The mixed solution in step (1) was adjusted to pH 7.5 with ammonia water, heated and stirred at 80°C for 7 hours to form a purple gel. When the volume of the gel expanded to 3 times the volume of the nitric acid solution, it was placed in a drying oven and baked at 160°C for 4 hours to form a dry gel. (3) The dry glue in step (2) is ground into powder in an agate mortar and placed in a box furnace at 600°C for 5 hours to remove hydrocarbons and decompose nitrates in the powder. (4) The solid powder after calcination in step (3) was ground with alcohol in an agate mortar for 2 hours and sintered in air at 1100°C for 10 hours to obtain a solid oxide battery bifunctional electrode material, denoted as NBC@Z4.

[0022] Example 2 (1) According to 10g NdBaCo 1.92 Zr 0.08 O 5+δ To achieve the desired stoichiometric ratio, Nd(NO3)3·6H2O, C4H6BaO4, Co(NO3)2·6H2O, and Zr(NO3)4·5H2O were added to a nitric acid solution (5g of concentrated nitric acid was added to 100mL of deionized water). Then, citric acid (C6H8O7·H2O) and EDTA were added to make the molar ratio of total metal cations, citric acid, and EDTA 1:1:0.8, forming a mixed solution. (2) The mixed solution in step (1) was adjusted to pH 7.5 with ammonia water, heated and stirred at 80°C for 7 hours to form a purple gel. When the volume of the gel expanded to 3 times the volume of the nitric acid solution, it was placed in a drying oven and baked at 180°C for 4 hours to form a dry gel. (3) The dry glue in step (2) is ground into powder in an agate mortar and placed in a box furnace and calcined at 600 °C for 5 hours to remove hydrocarbons and decompose nitrates in the powder; (4) The solid powder after calcination in step (3) is ground with alcohol in an agate mortar for 2 h, and sintered in air at 1100 °C for 10 h to obtain a solid oxide battery bifunctional electrode material, denoted as NBC@Z8.

[0023] Example 3 (1) According to 10g NdBaCo 1.88 Zr 0.12 O 5+δ To achieve the desired stoichiometric ratio, Nd(NO3)3·6H2O, C4H6BaO4, Co(NO3)2·6H2O, and Zr(NO3)4·5H2O were added to a nitric acid solution (5g of concentrated nitric acid was added to 100mL of deionized water). Then, citric acid (C6H8O7·H2O) and EDTA were added to make the molar ratio of total metal cations, citric acid, and EDTA 1:1:0.8, forming a mixed solution. (2) The mixed solution in step (1) was adjusted to pH 7.5 with ammonia water, heated and stirred at 80°C for 7 hours to form a purple gel. When the volume of the gel expanded to 3 times the volume of the nitric acid solution, it was placed in a drying oven and baked at 160°C for 4 hours to form a dry gel. (3) The dry glue in step (2) is ground into powder in an agate mortar and placed in a box furnace at 400~900℃ for 5 h to remove hydrocarbons and decompose nitrates in the powder; (4) The solid powder after calcination in step (3) is ground with alcohol in an agate mortar for 2 hours and sintered in air at 1100°C for 10 hours to obtain a solid oxide battery bifunctional electrode material, denoted as NBC@Z12.

[0024] Comparative Example 1 (1) According to 10g NdBaCo2O 5+δ To achieve the desired stoichiometric ratio, Nd(NO3)3·6H2O, C4H6BaO4, and Co(NO3)2·6H2O were added to a nitric acid solution (5g of concentrated HNO3 in 100mL of deionized water). Then, citric acid (C6H8O7·H2O) and EDTA were added to make the molar ratio of total metal cations, citric acid, and EDTA 1:1:0.8, forming a mixed solution. (2) The mixed solution in step (1) is heated and stirred to form a purple gel. When the volume of the gel expands to 3 times the volume of the nitric acid solution, it is placed in a drying oven and baked at 180 °C for 4 h to form a dry gel. (3) The dry glue in step (2) is ground into powder in an agate mortar and placed in a box furnace and calcined at 600 °C for 5 hours to remove hydrocarbons and decompose nitrates in the powder; (4) The solid powder after calcination in step (3) is ground with alcohol in an agate mortar for 2 hours and sintered in air at 1100 °C for 10 hours to obtain solid oxide battery electrode material, denoted as NBC.

[0025] Data representation (1) The X-ray diffraction patterns of NBC@Z4, NBC@Z8 and NBC@Z12 prepared in Examples 1-3 and NBC prepared in Comparative Example 1 are as follows: Figure 1 As shown, (a) is the overall view, and (b) is a magnified view of a part; from Figure 1 It can be seen that the NBC sample has a tetragonal double perovskite structure, with Zr 4+ With increasing doping concentration, the main diffraction peak shifts to the right, Zr 4+ The introduction of Ba element leads to its loss, which in turn results in a reduction in the unit cell volume.

[0026] (2) Thermal expansion curves of NBC@Z8 and NBC in air atmosphere: thermal expansion coefficient curve and electrical conductivity curve are shown below. Figure 2 As shown, (a) is the thermal expansion curve, and (b) is the electrical conductivity curve. Figure 2 (a) It can be seen that the thermal expansion curve shows a significant change in slope near 300℃, which can be attributed to the formation of oxygen vacancies and the simultaneous transition of cobalt cations from high oxidation state to low oxidation state; the thermal expansion behavior of the sample shows a near-linear trend in the range of 300 to 1000℃, indicating that no phase transition occurs in this temperature range; the average coefficient of thermal expansion (TEC) of NBC@Z8 is 21.3 × 10⁻⁶. -6 K - ¹, while the average TEC value for NBC is 23.1 × 10⁻¹. -6 K - ¹. Clearly, the average TEC of the NBC@Z8 sample is lower than that of the NBC sample. The high TEC of cobalt-based perovskite cathode materials is generally attributed to Co. 3+ Spin state transition of ions—that is, the conversion from a low-spin state to a high-spin state. When zirconium is introduced into the NBC structure, it reduces the amount of Co involved in spin transformation. 3+ The concentration of ions, thus leading to a decrease in TEC. (By...) Figure 2(b) It can be seen that within the temperature range of 500℃ to 800℃, the conductivity of both NBC and NBC@Z8 decreases with decreasing temperature, indicating that they exhibit metallic conductivity. The conductivity mechanism of the NBC and NBC@Z8 samples originates from the p-type small polaron transition mechanism achieved through electron-hole transport. The relatively low conductivity of the NBC@Z8 sample is mainly attributed to the following three aspects: First, zirconium ions replace cobalt sites, leading to a decrease in cobalt ion content and thus a reduction in carrier concentration; second, zirconium ions capture barium ions on the matrix surface, causing more cation defects to form at sites A and B of the matrix, thereby increasing the potential barrier for electron transition; finally, after capturing barium ions, zirconium ions form a high-spin structure on the matrix surface, enabling high-spin cobalt ions to form a low-spin-high-spin dual-state system in the matrix.

[0027] (3) The prepared NBC@Z4, NBC@Z8, NBC@Z12 and NBC electrode materials were mixed and ground with an organic binder (the mass ratio of ethyl cellulose to terpineol was 9:1) (the mass ratio of electrode to organic binder was 1:2) to form a uniformly mixed slurry as the electrode slurry; the electrode slurry was coated on both sides of the barrier layer GDC, and calcined at 1000℃ for 3 h in air atmosphere to obtain solid oxide batteries with symmetrical structures (NBC@BZ|GDC|NBC@BZ) with NBC@Z4, NBC@Z8 and NBC@Z12 and NBC as electrodes. The electrochemical performance test results are as follows: Figure 3 As shown, (a) is the typical impedance spectrum of the NBC oxygen electrode, (b) is the typical impedance spectrum of the NBC@Z4 oxygen electrode, (c) is the typical impedance spectrum of the NBC@Z8 oxygen electrode, (d) is the typical impedance spectrum of the NBC@Z12 oxygen electrode, (e) is the active surface area (ASR) value, (f) is the Arrhenius plot, (g) is the typical impedance spectrum of the NBC cathode at different oxygen partial pressure (Po2) levels at 700℃, and (h) is the typical impedance spectrum of the NBC@Z8 cathode at different Po2 levels at 700℃. Figure 3 (a) to (d) show the impedance spectra of the cathode on the GDC electrolyte in the temperature range of 650°C to 800°C. The areal resistivity (ASR) values ​​of each electrode at 800°C are: 0.094 Ω / cm² for the NBC electrode, 0.061 Ω / cm² for the NBC@Z4 electrode, 0.037 Ω / cm² for the NBC@Z8 electrode, and 0.071 Ω / cm² for the NBC@Z12 electrode. Figure 3 As shown in (e) and 3(f), NBC@Z8 exhibits the lowest ASR value and the lowest activation energy among all cathode materials, indicating its excellent catalytic activity in the oxygen reaction as an O-SOFC cathode material. Clearly, NBC@Z8 demonstrates superior oxygen catalytic activity compared to the NBC cathode. Figure 3(g) and (h) show the impedance spectra of NBC and NBC@Z8 at different oxygen partial pressures at 700 °C.

[0028] (4) First, NiO and YSZ powders were dry-ground at a mass ratio of 60:40 and a porous NiO-YSZ anode substrate was prepared by phase transformation casting. The substrate was pre-calcined at 1050℃ for 2 hours. Then, the anode functional layer and YSZ electrolyte were deposited sequentially by spin coating and co-calcined at 1400℃ for 10 hours to obtain a half cell. A GDC barrier layer was deposited on the surface of YSZ and sintered at 1250℃ for 3 hours. Then, cathode paste was screen-printed and sintered at 1000℃ for 3 hours to complete the preparation of a single cell (NBC@BZ|GDC|YSZ|NiO-YSZ).

[0029] The current-voltage characteristic curves and power density curves of a single cell using moist H2 as the fuel gas and air as the oxidizing gas in NBC@BZ|GDC|YSZ|NiO-YSZ are shown below. Figure 4 As shown, (a) is a single cell with NBC as the counter electrode, and (b) is a single cell with NBC@Z8 as the electrode. Figure 4 As shown in (a) and 4(b), at 800 °C, the maximum power density of the single cells using NBC and NBC@Z8 as electrodes reached 990 mW cm⁻¹. 2 and 1490 mW cm 2 Combined with the electrochemical impedance spectroscopy results, it is shown that the NBC@Z8 electrode has excellent electrochemical performance on YSZ electrolyte.

[0030] (5) NBC and NBC@Z8 were prepared into cathode pastes and coated on both sides of BZCYYb. The impedance under different water pressure conditions was tested, and the results are as follows: Figure 5 As shown, (a) uses NBC as the cathode, and (b) uses NBC@Z8 as the cathode. Figure 5 It can be seen that 3%P H2O Under these conditions, the polarization impedances of NBC and NBC@Z8 are approximately 0.35 Ω cm² and 0.3 Ω cm², respectively. In contrast, NBC@Z8 exhibits good proton conductivity, making it suitable for PCFC operation at high temperatures.

[0031] (6) Using moist H2 as fuel gas and air as oxidizing gas, with NBC and NBC@Z8 as cathodes and NiO-BZCYYb as anode, respectively, the current-voltage characteristics and output power density curves of the single cell NiO-BZCYYb|BZCYYb|cathode are as follows: Figure 6 As shown, (a) uses NBC as the cathode, and (b) uses NBC@Z8 as the cathode. Figure 6It can be seen that at 650 °C, the maximum power density of single cells using NBC and NBC@Z8 as cathodes is 720 mW cm⁻¹. 2 and 990 mW cm 2 It can be seen that the proton conductivity of NBC@Z8 with BaZrO3 heterostructure is enhanced, and the increase in oxygen vacancy concentration has a synergistic effect, further improving the proton conductivity of NBC@Z8.

Claims

1. A solid oxide battery bifunctional electrode material, characterized in that, The chemical formula of the solid oxide battery bifunctional electrode material is NdBaCo. 2–x Zr x O 5+δ The value of x is 0.04~0.

12.

2. The solid oxide battery bifunctional electrode material according to claim 1, characterized in that, The chemical formula of the solid oxide battery bifunctional electrode material is NdBaCo. 1.92 Zr 0.08 O 5+δ .

3. A method for preparing the solid oxide battery bifunctional electrode material according to claim 1 or 2, characterized in that, Includes the following steps: (1) According to NdBaCo 2–x Zr x O 5+δ According to the stoichiometric ratio, neodymium source, barium source, cobalt source and zirconium source are added to nitric acid solution, and then citric acid and EDTA are added to form a mixed solution; (2) The mixed solution in step (1) is adjusted to pH 7-8 with ammonia water, heated and stirred to form a gel. When the volume of the gel expands to 2.5-3.5 times the volume of the nitric acid solution, it is dried to obtain dry gel. (3) The dry adhesive in step (2) is calcined at 400~900℃ for 5~10h; (4) The solid after calcination in step (3) is ground with alcohol for 2 hours and sintered in air at 1000~1200℃ for 10 hours to obtain a solid oxide battery bifunctional electrode material.

4. The method for preparing the solid oxide battery bifunctional electrode material according to claim 3, characterized in that, The neodymium source mentioned in step (1) is Nd(NO3)3·6H2O, the barium source is C4H6BaO4, the cobalt source is Co(NO3)2·6H2O, and the zirconium source is Zr(NO3)4·5H2O; the nitric acid solution mentioned is a nitric acid solution prepared by adding 2~5g of concentrated nitric acid to 100mL of water.

5. The method for preparing the solid oxide battery bifunctional electrode material according to claim 3, characterized in that, In step (1), the total metal ions of neodymium source, barium source, cobalt source and zirconium source are in a molar ratio of 1:1~2:0.5~1 with citric acid and EDTA.

6. The method for preparing the solid oxide battery bifunctional electrode material according to claim 3, characterized in that, The heating and stirring conditions in step (2) are 80~100℃ for 5~8h.

7. The method for preparing the solid oxide battery bifunctional electrode material according to claim 3, characterized in that, In step (2), the drying conditions are to bake at 150~180℃ in a drying oven for 5~10 hours.

8. The application of a solid oxide battery bifunctional electrode material according to claim 1 or 2, or a solid oxide battery bifunctional electrode material prepared by any one of claims 3 to 7, in the preparation of solid fuel cells.

9. The application according to claim 8, characterized in that, The aforementioned solid oxide battery bifunctional electrode material serves as the cathode material for a solid fuel cell.

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