Air electrode and use thereof

Abstract

The application discloses an air electrode and application thereof, and belongs to the field of solid oxide batteries. The air electrode is formed by sintering an air electrode precursor in a CO2 atmosphere, and is a composite electrode of microparticles and nanoparticles. The size of the nanoparticles is 10-100 nm, the size of the microparticles is 0.5-2 microns, and the nanoparticles are uniformly dispersed on the surface of the microparticles. The composition of the air electrode precursor is Ba 1‑x N x Co 1‑m‑n Fe m M n O 3‑d , 0 < x < 0.5, 0 < n < 0.2, 0 < m < 0.3, 0 < d < 0.5, N is one or more than two of Sr, Mg, Ca, K and Na, and M is one or more than two of Sc, Zr, Nb, Ce, Y and Yb. The air electrode has excellent oxygen reduction and oxygen evolution reaction activity, and shows outstanding electrochemical performance in fuel cell power generation, hydrogen production by water vapor electrolysis and synthetic gas preparation by electrolysis.

Description

Technical Field

[0001] This invention belongs to the field of solid oxide batteries, specifically relating to an air electrode and its application. Background Technology

[0002] Solid oxide batteries (SOCs) possess advantages such as an all-solid-state structure, no need for precious metals, and good reversibility, making them promising for applications in power generation and hydrogen electrolysis. To further reduce the manufacturing cost of SOCs, researchers have focused on lowering their operating temperature below 600°C. However, as the operating temperature decreases, the battery performance significantly degrades. This is partly due to increased ohmic resistance and partly due to a significant decrease in the oxygen reduction or oxygen evolution reactivity of the air electrode at low temperatures. Researchers have also developed some highly active air electrode materials, such as perovskite (Ba,Sr)(Co,Fe)O3, but their stability in carbon dioxide or water vapor atmospheres is poor, and the stability issue still needs to be addressed before practical applications.

[0003] To improve the performance of air electrodes, researchers have developed nanoelectrodes using various techniques, such as impregnation. However, to achieve sufficient loading, multiple impregnation processes are typically required, leading to problems such as long processing times and high energy consumption. Therefore, there is an urgent need in this field to develop an air electrode material that exhibits excellent activity and stability at low temperatures. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides an air electrode, its preparation method, and its application. When applied in solid oxide batteries, the air electrode of this invention exhibits excellent activity and stability at 600°C.

[0005] The present invention provides an air electrode, wherein the air electrode is formed by sintering an air electrode precursor in a CO2 atmosphere to form a composite of micron-particles and nanoparticles, wherein the nanoparticles have a size of 10-100 nanometers and the micron-particles have a size of 0.5-2 micrometers, and the nanoparticles are uniformly dispersed on the surface of the micron-particles.

[0006] The air electrode precursor is composed of Ba. 1-x N x Co 1-m-n Fe m M n O 3-d , 0<x≤0.5, 0<n≤0.2, 0≤m≤0.3, 0≤d≤0.5, N is one or more of Sr, Mg, Ca, K, Na, and M is one or more of Sc, Zr, Nb, Ce, Y, Yb.

[0007] Furthermore, the composition of the air electrode precursor is Ba1-x N x Co 1-m-n Fe m M n O 3-d Wherein, N is one or more of Sr, Ca, Mg, and K; M is one or more of Sc, Zr, Nb, and Yb; 0 < x ≤ 0.3, 0 < n ≤ 0.15, 0 ≤ m ≤ 0.25, and 0 ≤ d ≤ 0.5.

[0008] Furthermore, the CO2 content in the CO2 atmosphere is 300-3000 ppm, and the sintering temperature is 700-1000℃.

[0009] Furthermore, the CO2 content in the CO2 atmosphere is preferably 300-1000 ppm, and the sintering temperature is preferably 700-850℃.

[0010] The present invention also provides an application of an air electrode, which is used in fuel cell power generation, electrolysis of water vapor to produce hydrogen, or electrolysis to produce syngas.

[0011] Furthermore, the air electrode is suitable for use in planar, tubular, or flat-tube solid oxide batteries.

[0012] The present invention also provides a membrane electrode for a solid oxide battery, the membrane electrode comprising a fuel electrode, an electrolyte and an air electrode, wherein the air electrode is the air electrode described above.

[0013] The present invention also provides a method for preparing a membrane electrode, wherein an air electrode precursor is mixed and ground with a binder and then coated onto the surface of an electrolyte, sintered in a CO2 atmosphere, and a fuel electrode is assembled to obtain the membrane electrode.

[0014] Furthermore, the sintering temperature is 700-1000℃, and the CO2 content in the CO2 atmosphere is 300-3000ppm.

[0015] Furthermore, the adhesive includes: ethyl cellulose-terpineol adhesive or polyvinyl butyral-n-butanol adhesive.

[0016] The air electrode precursor Ba of the present invention 1-x N x Co 1-m-n Fe m M n O 3-dIn this process, the modulation of nitrogen at the A-site increases the number of oxygen vacancies and migration activity, enhances the oxygen exchange activity on the material surface, and modulates the material's electrical conductivity and expansion behavior, enabling it to maintain excellent performance at low temperatures. The modulation of nitrogen at the B-site enhances the catalytic activity for oxygen surface reduction or precipitation, stabilizes the material's structure, and allows it to exhibit good stability in carbon dioxide or water vapor atmospheres.

[0017] Beneficial effects of the invention

[0018] The air electrode Ba of this invention 1-x N x Co 1-m-n Fe m M n O 3-d It has a composite structure of micron-sized particles and nano-sized particles, with nanoparticles having a size of 10–100 nanometers and micron-sized particles having a size of 0.5–2 micrometers. The nanoparticles are uniformly dispersed on the surface of the micron-sized particles, which greatly increases the reactive sites and improves the electrode performance.

[0019] The electrode structure can be achieved through atmosphere and temperature control, and its formation mechanism is as follows: Ba 1-x N x Co 1-m- n Fe m M n O 3-d It possesses a perovskite structure, with B-site (Co, Fe, M) transition metal ions as the central ion, coordinating with eight surrounding oxygen ions to form BO6 octahedra, which are connected in a shared-vertex manner to form a network; A-site (Ba, N) alkaline earth ions coordinate with twelve surrounding O ions, occupying the gaps between the BO6 octahedra, forming a layered stacked structure. First, Ba... 1-x N x Co 1-m-n Fe m M n O 3-d When air electrodes are sintered in a CO2 atmosphere containing ppm levels, alkaline earth ions are gradually released from the outermost A-site of the perovskite structure, leading to a severe imbalance of surface charge, severe distortion and deformation of the BO6 octahedron, and the formation of alkaline earth metal carbonates or transition metal oxides on the electrode surface. Then, at high temperatures, the released alkaline earth and transition metal carbonates or oxides react again to form nanoscale Ba... 1- x N x Co 1-m-n Fe m M n O 3-d And dispersed in micron-sized Ba 1-x N x Co1-m-n Fe m M n O 3-d surface.

[0020] The micron-nano composite air electrode of this invention exhibits low fabrication cost and excellent electrode activity. Using the Ba of this invention… 1-x N x Co 1-m-n Fe m M n O 3-d As an air electrode, it can reduce the operating temperature of solid oxide batteries to 600°C. Attached Figure Description

[0021] Figure 1 For Ba 0.9 Sr 0.1 Co 0.8 Fe 0.1 Sc 0.1 O 2.7 Air electrode structure. Detailed Implementation

[0022] The following non-limiting embodiments are intended to enable those skilled in the art to more fully understand the present invention, but do not limit the invention in any way.

[0023] Comparative Example 1

[0024] Perovskite oxide Ba was prepared by solid-state reaction using 0.009 mol BaCO3, 0.001 mol SrCO3, 0.0075 mol CoO, 0.001 mol FeO, 0.001 mol ZrO2, and 0.00025 mol Yb2O3 as raw materials. 0.9 Sr 0.1 Co 0.75 Fe 0.1 Zr 0.1 Yb 0.05 O 2.65 The solid-state reaction sintering temperature was 1100℃, the sintering time was 5h, and the resulting powder was ground in a planetary ball mill for 2h.

[0025] 0.5g of Ba 0.9 Sr 0.1 Co 0.75 Fe 0.1 Zr 0.1 Yb 0.05 O 2.65An air electrode slurry was prepared by mixing and grinding 0.5 g of electrode binder (6% ethyl cellulose in terpineol). This slurry was then coated onto the electrolyte surface and calcined at 800 °C for 2 hours in a high-purity (99.999%) oxygen atmosphere to obtain a complete hydrogen electrode-supported membrane electrode. Electrochemical tests and morphological characterization were then performed. The obtained air electrode consisted of micron-sized particles ranging from 0.5 to 1.2 μm. At 600 °C and 1.3 V, the current density for electrolyzing water vapor reached 0.21 A / cm². -2 At 0.2Acm -2 After operating at a constant current density for 100 hours, the electrolysis voltage increased from 1.31V to 1.45V.

[0026] Comparative Example 2

[0027] Perovskite oxide Ba was prepared by solid-state reaction using 0.009 mol BaCO3, 0.001 mol SrCO3, 0.003 mol CoO, 0.0055 mol FeO, 0.001 mol ZrO2, and 0.00025 mol Yb2O3 as raw materials. 0.9 Sr 0.1 Co 0.3 Fe 0.55 Zr 0.1 Yb 0.05 O 2.65 The preparation conditions were the same as those for Comparative Example 1. 0.5 g of Ba... 0.9 Sr 0.1 Co 0.3 Fe 0.55 Zr 0.1 Yb 0.0 5O 2.65 An air electrode slurry was prepared by mixing and grinding 0.5 g of electrode binder (6% ethyl cellulose in terpineol). This slurry was then coated onto the electrolyte surface and calcined at 1100 °C for 2 hours in an atmosphere containing 500 ppm CO2 to obtain a complete hydrogen electrode-supported membrane electrode. Electrochemical tests and morphological characterization were then performed. The resulting air electrode exhibited a composite structure of micron- and nanoparticles, with nanoparticles ranging from 100 to 200 nm in size and micron-sized particles ranging from 0.5 to 0.8 μm in size, dispersed on the surface of the micron-particles. At 600 °C and 1.3 V, the current density for electrolyzing water vapor reached 0.26 A / cm². -2 At 0.2Acm -2 After operating at a constant current density for 100 hours, the electrolysis voltage increased from 1.25V to 1.30V.

[0028] Comparative Example 3

[0029] Perovskite oxide BaCo was prepared by solid-state reaction using 0.01 mol BaCO3, 0.008 mol CoO, 0.001 mol FeO, and 0.001 mol CeO2 as raw materials. 0.8 Fe 0.1 Ce 0.1 O 2.8 The preparation conditions were the same as those for Comparative Example 1. 0.5 g of BaCo... 0.8 Fe 0.1 Ce 0.1 O 2.8 An air electrode slurry was prepared by mixing and grinding 0.5 g of electrode binder (6% ethyl cellulose in terpineol). This slurry was then coated onto the electrolyte surface and calcined at 950 °C for 2 hours in an atmosphere containing 400 ppm CO2 to obtain a complete hydrogen electrode-supported membrane electrode. Electrochemical tests and morphological characterization were then performed. The resulting air electrode exhibited a composite structure of micron- and nanoparticles, with nanoparticles measuring 80–100 nm and micron-sized particles measuring 1–2 μm. The nanoparticles were uniformly dispersed on the surface of the micron-sized particles. At 600 °C and 1.3 V, the current density for electrolyzing water vapor reached 0.3 A / cm². -2 At 0.2Acm -2 After operating at a constant current density for 100 hours, the electrolysis voltage increased from 1.21V to 1.33V.

[0030] Example 1

[0031] Perovskite oxide BaCO3 was prepared by solid-state reaction using 0.009 mol BaCO3, 0.001 mol MgCO3, 0.008 mol CoO, 0.001 mol FeO, and 0.001 mol CeO2 as raw materials. 0.9 Mg 0.1 Co 0.8 Fe 0.1 Ce 0.1 O 2.8 The preparation conditions were the same as those for Comparative Example 1. 0.5 g of Ba... 0.9 Mg 0.1 Co 0.8 Fe 0.1 Ce 0.1 O 2.8An air electrode slurry was prepared by mixing and grinding 0.5 g of electrode binder (6% ethyl cellulose in terpineol). This slurry was then coated onto the electrolyte surface and calcined at 950 °C for 2 hours in an atmosphere containing 400 ppm CO2 to obtain a complete hydrogen electrode-supported membrane electrode. Electrochemical tests and morphological characterization were then performed. The resulting air electrode exhibited a composite structure of micron- and nanoparticles, with nanoparticles measuring 60–80 nm and micron-sized particles measuring 1–2 μm. The nanoparticles were uniformly dispersed on the surface of the micron-sized particles. At 600 °C and 1.3 V, the current density for electrolyzing water vapor reached 0.32 A / cm². -2 At 0.2Acm -2 After operating at a constant current density for 100 hours, the electrolysis voltage increased from 1.20V to 1.25V.

[0032] Example 2

[0033] Perovskite oxide BaCO3 was prepared by solid-state reaction using 0.009 mol BaCO3, 0.001 mol SrCO3, 0.008 mol CoO, 0.001 mol FeO, and 0.0005 mol Sc2O3 as raw materials. 0.9 Sr 0.1 Co 0.8 Fe 0.1 Sc 0.1 O 2.7 The preparation conditions were the same as those for Comparative Example 1. 0.5 g of Ba... 0.9 Sr 0.1 Co 0.8 Fe 0.1 Sc 0.1 O 2.7 An air electrode slurry was prepared by mixing and grinding 0.5 g of electrode binder (6% ethyl cellulose in terpineol). The air electrode slurry was coated onto the electrolyte surface and calcined at 850 °C for 2 hours in an atmosphere containing 500 ppm CO2 to obtain a complete hydrogen electrode-supported membrane electrode. Electrochemical tests and morphological characterization were then performed. The obtained air electrode has a composite structure of micron- and nanoparticles, with nanoparticles having a size of 30–50 nm and micron-sized particles of 0.5–0.8 μm. The nanoparticles are uniformly dispersed on the surface of the micron-sized particles. SEM images are attached. Figure 1 As shown, at 600℃ and 1.3V, the current density for electrolyzing water vapor reaches 0.48 A / cm². -2 At 0.2Acm -2 After operating at a constant current density for 100 hours, the electrolysis voltage increased from 1.15V to 1.16V.

[0034] Example 3

[0035] Perovskite oxide Ba was prepared by solid-state reaction using 0.009 mol BaCO3, 0.001 mol SrCO3, 0.0075 mol CoO, 0.001 mol FeO, 0.001 mol ZrO2, and 0.00025 mol Yb2O3 as raw materials. 0.9 Sr 0.1 Co 0.75 Fe 0.1 Zr 0.1 Yb 0.05 O 2.65 The preparation conditions were the same as those for Comparative Example 1. 0.5 g of Ba... 0.9 Sr 0.1 Co 0.75 Fe 0.1 Zr 0.1 Yb 0.0 5O 2.65 An air electrode slurry was prepared by mixing and grinding 0.5 g of electrode binder (6% ethyl cellulose in terpineol). This slurry was then coated onto the electrolyte surface and calcined at 800 °C for 2 hours in an atmosphere containing 500 ppm CO2 to obtain a complete hydrogen electrode-supported membrane electrode. Electrochemical tests and morphological characterization were then performed. The resulting air electrode exhibited a composite structure of micron- and nanoparticles, with nanoparticles ranging from 30 to 50 nm in size and micron-sized particles ranging from 0.5 to 0.8 μm in size. The nanoparticles were uniformly dispersed on the surface of the micron-sized particles. At 600 °C and 1.3 V, the current density for electrolyzing water vapor reached 0.73 A / cm². -2 At 0.2Acm -2 After operating at a constant current density for 100 hours, the electrolysis voltage increased from 1.08V to 1.081V.

[0036] Example 4

[0037] Perovskite oxide Ba was prepared by solid-state reaction using 0.009 mol BaCO3, 0.001 mol SrCO3, 0.003 mol CoO, 0.0055 mol FeO, 0.001 mol ZrO2, and 0.00025 mol Yb2O3 as raw materials. 0.9 Sr 0.1 Co 0.3 Fe 0.55 Zr 0.1 Yb 0.05 O 2.65 The preparation conditions were the same as those for Comparative Example 1. 0.5 g of Ba... 0.9 Sr 0.1 Co 0.3 Fe 0.55 Zr 0.1 Yb 0.05O 2.65 An air electrode slurry was prepared by mixing and grinding 0.5 g of electrode binder (6% ethyl cellulose in terpineol). This slurry was then coated onto the electrolyte surface and calcined at 800 °C for 2 hours in an atmosphere containing 500 ppm CO2 to obtain a complete hydrogen electrode-supported membrane electrode. Electrochemical tests and morphological characterization were then performed. The resulting air electrode exhibited a composite structure of micron- and nanoparticles, with nanoparticles ranging from 30 to 50 nm in size and micron-sized particles ranging from 0.5 to 0.8 μm in size. The nanoparticles were uniformly dispersed on the surface of the micron-particles. At 600 °C and 1.3 V, the current density for electrolyzing water vapor reached 0.46 A / cm². -2 At 0.2Acm -2 After operating at a constant current density for 100 hours, the electrolysis voltage increased from 1.15V to 1.17V.

Claims

1. An air electrode characterized by: The air electrode is a micro-particle and nano-particle composite electrode formed after sintering of the air electrode precursor in a CO2-containing atmosphere, the nano-particle size is 10-100 nm, the micro-particle size is 0.5-2 microns, and the nano-particles are uniformly dispersed on the surface of the micro-particles; the composition of the air electrode precursor is Ba 1- x N x Co 1-m-n Fe m M n O 3-d , 0 < x < 0.5, 0 < n < 0.2, 0 < m < 0.3, 0 < d < 0.5, N is one or more than two of Sr, Mg, Ca, K, Na, and M is one or more than two of Sc, Zr, Nb, Ce, Y and Yb.

2. An air electrode according to claim 1, wherein: The composition of the air electrode precursor is Ba 1- x N x Co 1-m-n Fe m M n O 3-d , N is one or more than two of Sr, Ca, Mg, K; M is one or more than two of Sc, Zr, Nb, Yb; 0 < x ≤ 0.3, 0 < n ≤ 0.15, 0 ≤ m ≤ 0.25, 0 ≤ d ≤ 0.

5.

3. An air electrode according to claim 1, wherein: The content of CO2 in the CO2 atmosphere is 300-3000 ppm, and the sintering temperature is 700-1000 DEG C.

4. An air electrode according to claim 1, wherein: The content of CO2 in the CO2 atmosphere is 300-1000 ppm, and the sintering temperature is 700-850 DEG C.

5. Use of the air electrode according to any one of claims 1 to 4, characterized in that: The air electrode is applied to fuel cell power generation, hydrogen production by water vapor electrolysis or power supply for preparing synthesis gas by electrolysis.

6. Use according to claim 5, characterized in that: The air electrode is applied to flat plate type, tube type or flat tube type solid oxide cell.

7. A membrane electrode of a solid oxide cell, the membrane electrode comprising a fuel electrode, an electrolyte and an air electrode, characterized in that: The air electrode is the air electrode according to any one of claims 1-4.

8. A method of making a membrane electrode as defined in claim 7, characterized by: The air electrode precursor is mixed and grinded with a binder, coated on the surface of an electrolyte, sintered in a CO2 atmosphere, combined with a fuel electrode to obtain the membrane electrode.

9. The method of claim 8, wherein: The temperature of the sintering is 700-1000 o C, the content of CO2 in the CO2 atmosphere is 300-3000 ppm.

10. The method of claim 8, wherein: The binder comprises ethyl cellulose-terpineol binder or polyvinyl butyral-n-butanol binder.

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