An oxygen electrode material, an automotive oxygen sensor electrode, an oxygen electrode interface layer, and a solid oxide battery stack.

Abstract

This invention provides an oxygen electrode material, an automotive oxygen sensor electrode, an oxygen electrode interface layer, and a solid oxide battery stack, relating to the field of oxygen electrode material technology. The oxygen electrode material includes LaCo... 0.6‑x Fe x Ni 0.4 O 3‑δ Materials. A novel perovskite ceramic material is used as the electrode material for the oxygen sensor, offering advantages such as low cost, strong interfacial adhesion, and good thermal behavior matching with the substrate. This invention also provides an oxygen electrode interface bonding layer, comprising a LaCo layer facing the metal connector surface. 0.6‑ x Fe x Ni 0.4 O 3‑δ LaCo layer facing the oxygen electrode surface of a single cell 0.6‑x Fe x Ni 0.4 O 3‑δ The structure consists of a layer, an LCN-NM layer between them, forming a sandwich structure. This structure exhibits both high conductivity and is compatible with the thermal expansion behavior of the single cell and the metal interconnect.

Description

Technical Field

[0001] This invention relates to the field of oxygen electrode materials technology, and more particularly to an oxygen electrode material with matched thermal expansion behavior, an oxygen sensor electrode for vehicles, and an oxygen electrode interface bonding layer and a solid oxide battery stack formed from the material. Background Technology

[0002] Solid oxide batteries (SOCs) are a clean and efficient energy conversion technology that can operate in both solid oxide fuel cells (SOFCs) and solid oxide electrolyzers (SOECs). In SOFC mode, the chemical energy of hydrocarbon fuels can be directly converted into electrical energy. Because there is no combustion or mechanical movement, it offers advantages such as high efficiency, no noise, and a wide availability of fuel sources. In SOEC mode, high-purity hydrogen can be obtained through water electrolysis, offering advantages such as lower energy consumption and higher conversion rates compared to conventional alkaline electrolyzers and proton exchange membrane fuel cells. SOC technology significantly reduces energy loss and environmental impact during energy conversion, thus showing broad application prospects in stationary power plants, mobile power sources, and transportation. Given the limited power of a single SOC cell, multiple cells are typically connected in series with metal connectors to form stacks of different power levels. However, the performance degradation rate of a stack after assembling individual cells is much higher than that of a single cell, especially after the stack undergoes thermal cycling, which significantly increases the degradation rate. Factors contributing to fuel cell stack performance degradation include the evolution of single-cell electrode structures, high-temperature oxidation of metal interconnects, failure of sealing materials, and increased interfacial contact resistance between adjacent components. Among these, the increase in interfacial resistance during long-term operation and thermal cycling has a significant impact on performance degradation. Studies have shown that the surface resistivity of the oxygen electrode / metal interconnect interface is much higher than that of the hydrogen electrode / metal interconnect interface. Therefore, the interfacial bonding performance between the oxygen electrode and the metal interconnect has become a bottleneck restricting the development of mid-temperature SOC technology.

[0003] The oxygen electrode interface bonding material for fuel cell stacks is a ceramic powder with high-temperature electronic conductivity. During stack assembly, it is screen-printed onto the surface of the oxygen electrode in single-cell form as a paste. Its main functions are to improve the interfacial contact state and collect surface electrons of the oxygen electrode, while also inhibiting high-temperature oxidation of the metal interconnect. The oxygen electrode interface bonding material improves the electronic conductivity of the oxygen electrode surface, increasing the current collection efficiency of the metal interconnect. Simultaneously, air needs to diffuse through the interface material layer into the porous oxygen electrode. Therefore, the oxygen electrode interface material must meet three core requirements: high conductivity, thermal expansion matching with adjacent components, and sufficient porosity.

[0004] Cobalt-containing perovskite materials are often used as oxygen electrode materials or interface bonding materials in solid oxide batteries due to their high oxygen reduction activity and high-temperature conductivity, such as La.0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ (LSCF). Because LSCF has low electronic conductivity at high temperatures, while LaCo... 0.6 Ni 0.4 O 3-δ Cobalt-containing perovskite (LCN) exhibits excellent functional properties as an oxygen electrode interface material. Its electrical conductivity exceeds 1300 S / cm in the temperature range of 100–800 °C, demonstrating good electronic conductivity, and it also shows good chemical compatibility with Fe-Cr linked alloys. However, cobalt-containing perovskite materials typically have a high coefficient of thermal expansion, mainly attributed to the thermal reduction of cobalt ions, related phase transitions, and the thermal activation transition of the cobalt d-orbital electron spin state. The coefficient of thermal expansion of LCN in the 100–800 °C temperature range is approximately 17.54 × 10⁻⁶. -6 K -1 It is far superior to Fe-Cr bonded alloy (12.5×10). -6 K -1 ) and single cell (12×10 -6 K -1 This leads to thermal expansion mismatch in single cells during thermal cycling, causing thermal stress concentration and crack initiation, resulting in a sharp increase in ohmic impedance and rapid performance degradation. Therefore, enhancing the thermal expansion coefficient matching of the oxygen electrode interface material while ensuring conductivity has become a key technical problem in solving the thermal cycling problem of fuel cell stacks. Some research has been conducted to reduce the thermal expansion coefficient of cobalt-containing perovskite oxygen electrode interface materials. For example, doping the perovskite lattice with d... 0 Transition metals for orbitals, compositing perovskite materials with electrolyte materials, introducing A-site defects into perovskites, or forming thermal expansion-inhibiting phases in situ have all been explored. However, these strategies can only reduce the coefficient of thermal expansion of cobalt-containing perovskite materials to a limited extent, failing to fully match the coefficients of thermal expansion of the metal interconnects and SOC components, and potentially negatively impacting oxygen reduction reaction activity. Therefore, it is crucial to find an oxygen electrode interface material that combines matching coefficients of thermal expansion, high-temperature conductivity, high electrochemical activity, and strong interfacial stability.

[0005] On the other hand, automotive oxygen electrode sensors are devices installed in the engine exhaust system to monitor the oxygen content in the exhaust gas in real time, thereby determining the air-fuel ratio (λ) and feeding the signal back to the engine control unit to achieve precise air-fuel ratio control (λ≈1) and improve fuel economy. Automotive oxygen sensors typically use YSZ solid electrolyte as a matrix, utilizing the high-temperature conductivity of oxygen ions to detect oxygen concentration in the exhaust gas. The electrode material and its microstructure play a crucial role in the sensor's output characteristics, dynamic response, and long-term stability. Traditional oxygen sensor electrode materials use platinum electrodes, which suffer from high raw material costs and poor high-temperature stability (poor matching with the thermal behavior of the matrix). Therefore, developing low-cost, high-stability alternative electrode materials remains a research focus. Summary of the Invention

[0006] To address the above issues, this invention employs a novel perovskite ceramic material as the oxygen sensor electrode material, which offers advantages such as low cost, strong interfacial adhesion, and good thermal behavior matching with the substrate. Furthermore, an oxygen electrode interface connection layer structure is proposed, which possesses both high conductivity and matches the thermal expansion behavior of the single cell and the metal connector. While maintaining high conductivity, this ensures good contact between the single-cell oxygen electrode and the metal connector interface, enabling effective collection of current from the oxygen electrode surface and thus guaranteeing the performance stability of the fuel cell stack during long-term operation and thermal cycling.

[0007] One of the objectives of this invention is to provide an oxygen electrode material.

[0008] The second objective of this invention is to provide an automotive oxygen sensor electrode that includes the oxygen electrode material.

[0009] A third objective of this invention is to provide an oxygen electrode interface bonding layer comprising the oxygen electrode material.

[0010] The fourth objective of this invention is to provide a solid oxide battery stack including the oxygen electrode interface connection layer.

[0011] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted:

[0012] In a first aspect, the present invention provides an oxygen electrode material, comprising LaCo... 0.6-x Fe x Ni 0.4 O 3-δ The material has a density of 0.1 ≤ x ≤ 0.4 (preferably 0.2 ≤ x ≤ 0.3), where δ is the oxygen vacancy concentration, determined by the charge balance of the material, and 0 ≤ δ < 0.3.

[0013] In some implementations, LaCo 0.6-x Fe x Ni0.4 O 3-δ The particle size of the material is 0.1-0.2 μm.

[0014] When the Fe element doping amount is controlled within a reasonable range, x is between 0.1 and 0.4, preferably between 0.2 and 0.3, and more preferably 0.3, the oxygen electrode constructed from this material has suitable high-temperature conductivity and thermal expansion matching.

[0015] LaCo 0.6-x Fe x Ni 0.4 O 3-δ The material can be obtained by coprecipitation to obtain the precursor, followed by calcination.

[0016] Secondly, the present invention provides an automotive oxygen sensor electrode, comprising the aforementioned oxygen electrode material.

[0017] The automotive oxygen sensor electrode includes an inner electrode located inside the zirconium tube preform and an outer electrode located outside the zirconium tube preform. Both the inner and outer electrodes are made of LaCo material. 0.6-x Fe x Ni 0.4 O 3-δ Material.

[0018] The automotive oxygen sensor electrode formed from the above-mentioned oxygen electrode material has good thermal behavior matching with the substrate and good high-temperature stability.

[0019] Thirdly, the present invention provides an oxygen electrode interface connection layer comprising the above-mentioned oxygen electrode material.

[0020] Furthermore, the solid oxide battery stack oxygen electrode interface bonding layer includes a LaCo layer facing the surface of the metal connector. 0.6-x Fe x Ni 0.4 O 3-δ LaCo layer facing the oxygen electrode surface of a single cell 0.6-x Fe x Ni 0.4 O 3-δ The layers, and the LCN-NM layer between them, form a sandwich structure;

[0021] The LaCo 0.6-x Fe x Ni 0.4 O 3-δ Layers made of LaCo 0.6-x Fe x Ni 0.4 O 3-δMaterial composition, wherein 0.1≤x≤0.4 (preferably 0.2≤x≤0.3), δ is the oxygen vacancy concentration, which is determined by the charge balance of the material, 0≤δ<0.3;

[0022] The LCN-NM layer is made of LaCo 0.6 Ni 0.4 O 3-δ (LCN) and NdMnO 3-δ The composite material is composed of (NM), in which NdMnO 3-δ The material's mass percentage is 20-50 wt% (i.e., NdMnO). 3-δ (The percentage of the material in the composite material by mass), preferably 40 wt%.

[0023] LaCo 0.6 Ni 0.4 O 3-δ δ, NdMnO 3-δ δ and LaCo 0.6-x Fe x Ni 0.4 O 3-δ The δ in the text has the same meaning, both representing oxygen vacancy concentration, with a value range of 0 ≤ δ < 0.3.

[0024] In some embodiments, LaCo faces the surface of the metal connector and the surface of the single-cell oxygen electrode. 0.6- x Fe x Ni 0.4 O 3-δ The thickness of each layer is 3-6 μm, preferably 5 μm; the thickness of the LCN-NM layer is 10-20 μm, preferably 10 μm.

[0025] In some implementations, LaCo 0.6-x Fe x Ni 0.4 O 3-δ The material has a particle size of 0.1-0.2 μm; LaCo 0.6 Ni 0.4 O 3-δ and NdMnO 3-δ The particle size of the composite material is 0.2-1.5 μm.

[0026] The oxygen electrode interface connection layer is a porous conductive layer filled between the oxygen electrode and the metal connector of a single cell. It is mainly composed of ceramic powder material. In order to further optimize the oxygen electrode interface connection layer, this invention will regulate its current collection efficiency and performance stability by constructing the oxygen electrode interface structure.

[0027] like Figure 10This is a schematic diagram of the oxygen electrode interface connection layer with a sandwich structure, whose structure mainly consists of an ultrathin LaCo layer. 0.6-x Fe x Ni 0.4 O 3-δ Layer 21 (facing the surface of metal connector 1) - thicker LCN-NM layer; Layer 22 (middle) - ultra-thin LaCo 0.6-x Fe x Ni 0.4 O 3-δ The structure consists of three layers, with layer 21 (facing the oxygen electrode surface of single cell 3). Preferably, both sides are LaCo... 0.6- x Fe x Ni 0.4 O 3-δ The layers are made of the same material. Ultra-thin LaCo layers are located on both sides. 0.6-x Fe x Ni 0.4 O 3-δ The layer has a relatively dense microstructure, and its main function is to provide good current collection effect for the oxygen electrode and the metal connector. The powder particles of the middle LCN-NM layer are coarse and have a relatively loose microstructure. They can use their good thermal expansion matching to dissipate the thermal stress generated during the cold and hot cycle of the fuel cell stack, thereby ensuring the integrity of the electrical connection structure between the fuel cell stack interfaces.

[0028] LaCo 0.6-x Fe x Ni 0.4 O 3-δ layer:

[0029] Based on LaCo 0.6 Ni 0.4 O 3-δ Perovskite materials, by doping the B-sites of the perovskite structure with Fe to partially replace Co, thereby reducing the coefficient of thermal expansion. Within a temperature range of room temperature to 800℃, LaCo… 0.6-x Fe x Ni 0.4 O 3-δ The coefficient of thermal expansion of the material can be adjusted to match the coefficient of thermal expansion of the oxygen electrode material (LSCF-GDC) and the metal interconnect (Fe-16Cr alloy). On the other hand, LaCo... 0.6-x Fe x Ni 0.4 O 3-δThe material exhibits an electrical conductivity exceeding 200 S / cm in the operating temperature range of 600 to 800 °C. To reduce the coefficient of thermal expansion while maintaining relatively high electrical conductivity, the Fe doping amount is controlled within a reasonable range, with x between 0.1 and 0.4, preferably between 0.2 and 0.3, and more preferably 0.3. As a result, the oxygen electrode interface bonding layer constructed from this material possesses suitable high-temperature conductivity and thermal expansion matching, which can improve the thermal cycling stability of the fuel cell stack.

[0030] LaCo 0.6-x Fe x Ni 0.4 O 3-δ The precursor can be obtained by co-precipitation, and then calcined to obtain powder; the powder is made into a slurry, coated and then heat-treated.

[0031] LCN-NM layer:

[0032] LaCo, which has high electronic conductivity 0.6 Ni 0.4 O 3-δ Using LCN material as the matrix, a certain amount of NdMnO is composited into it. 3-δ (NM) material is used to improve thermal expansion matching with adjacent SOC components. It utilizes their opposite thermal expansion behavior to enhance the matching of thermal expansion coefficients between the composite oxygen electrode interface material and adjacent SOC components. NM is a negative thermal expansion material with a thermal expansion coefficient of approximately -7.8 × 10⁻⁶ in the temperature range of 100 to 800 °C. -6 K -1 Therefore, LCN and NM powders can be combined in a certain proportion to reduce the high thermal expansion coefficient of LCN. The thermal expansion coefficient of this composite material can be adjusted to an appropriate range by adjusting the component ratio. Meanwhile, to maintain high electrical conductivity, the mass ratio of NM is approximately 20wt% to 50wt%, preferably 40wt%. Another advantage of NM is that it does not chemically react with LCN and conventional oxygen electrode material LSCF-GDC at the SOC operating temperature of 600 to 800°C, indicating good chemical compatibility and ensuring the long-term operational stability of this composite material as the oxygen electrode interface layer. The improved oxygen electrode interface bonding material not only exhibits excellent current collection performance but also significantly reduces the thermal expansion coefficient of the oxygen electrode interface layer, thereby enhancing the thermal cycling stability of the fuel cell stack.

[0033] The LCN-NM layer can be obtained by coating a slurry made from composite powder and then heat-treating it.

[0034] This invention selects LaCo 0.6 Ni 0.4 O 3-δBased on perovskite ceramics (LCN), material modification is performed by substituting Fe for Co at the B-site of the perovskite lattice to reduce its coefficient of thermal expansion. A certain amount of negative thermal expansion (NTE) material is incorporated to further reduce the coefficient of thermal expansion of the composite material. These two materials are then combined to form a sandwich structure, fully leveraging their advantages in high-temperature conductivity and coefficient of thermal expansion matching. Ultimately, this improves the coefficient of thermal expansion matching between the oxygen electrode interface structure and adjacent components while appropriately reducing conductivity. Compared with noble metal interface materials such as platinum, the oxygen electrode interface layer prepared in this invention has advantages such as low cost, simple structure, good chemical compatibility, and stable interface connection. 0.9 Sr 0.1 MnO 3-δ Compared to ceramic materials, it has advantages such as high high-temperature conductivity and the ability to quickly dissipate heat stress.

[0035] The method for preparing the oxygen electrode interface bonding layer of the above-mentioned solid oxide battery stack includes the following steps:

[0036] LaCo was sequentially coated onto the surface of the oxygen electrode of a single cell using screen printing. 0.6-x Fe x Ni 0.4 O 3-δ Material slurry, LaCo 0.6 Ni 0.4 O 3-δ and NdMnO 3-δ Composite slurry, LaCo 0.6-x Fe x Ni 0.4 O 3-δ The material is slurry, and then heat-treated at a temperature of 750-800℃.

[0037] Fourthly, the present invention provides a solid oxide battery stack, comprising a solid oxide battery stack oxygen electrode interface connection layer disposed between the oxygen electrode of a single cell and a metal connector.

[0038] Figure 11 This is a partial structural diagram of a solid oxide battery stack. The main components are a repeating structural unit consisting of a metal connector 1, an oxygen electrode interface connection layer 2, a single cell 3 (which includes, in sequence, an oxygen electrode layer 31, an oxygen electrode barrier layer 32, an electrolyte layer 33, a hydrogen electrode functional layer 34, and a hydrogen electrode support 35), a hydrogen electrode interface layer 4, and a metal connector 1.

[0039] Beneficial effects:

[0040] (1) The present invention uses a novel perovskite ceramic material as the oxygen sensor electrode material, which has the advantages of low cost, strong interfacial bonding and good thermal behavior matching with the substrate. This oxygen sensor electrode can not only meet the requirements of dynamic oxygen concentration response, but also replace platinum electrodes, and has the advantage of low cost.

[0041] (2) In this invention, a LaCo layer with a thickness of approximately 5 μm is formed on the surface of the oxygen electrode and the metal connector of a single cell. 0.6- x Fe x Ni 0.4 O 3-δ Oxygen electrode interface layer. In-situ sintering of ultrafine powder materials at SOC operating temperature facilitates the formation of a high-temperature conductive coating with good interfacial bonding between the single-cell oxygen electrode and the metal interconnect surface; the ultrathin coating structure helps enhance its mechanical properties to prevent peeling under thermal stress; after composition optimization, LaCo… 0.6-x Fe x Ni 0.4 O 3-δ The material can meet the dual requirements of high-temperature conductivity and thermal expansion coefficient of the oxygen electrode interface layer.

[0042] (3) The present invention relates to a single-cell oxygen electrode LaCo 0.6-x Fe x Ni 0.4 O 3-δ A 10μm to 20μm thick LCN-NM composite material layer is formed on top of the coating, thereby achieving the purpose of electrical connection and thermal stress dissipation at the oxygen electrode interface. By adjusting the relative proportion of LCN-NM composite material, the coefficient of thermal expansion of the composite material can be controlled to achieve a balance between high-temperature conductivity and thermal expansion matching; the larger particle size of LCN-NM composite material can ensure the stability of its microstructure and structure during long-term operation.

[0043] (4) The surface of the single-cell oxygen electrode and the metal connector of the present invention has a LaCo thickness of approximately 5 μm. 0.6-x Fe x Ni 0.4 O 3-δ The novel oxygen electrode interface consists of three coatings of different materials and thicknesses. The ultrathin coating interface, which is directly adjacent to the single-cell oxygen electrode and the metal connector, has high conductivity and fine particles, enabling efficient current collection on the surface of the single-cell oxygen electrode. The thicker intermediate coating has a matching coefficient of thermal expansion and coarse particles, which ensures the stable structure of the interface layer under high-temperature operating conditions and can dissipate thermal stress caused by thermal expansion mismatch.

[0044] The present invention has been described in detail above; however, the above embodiments are merely illustrative in nature and are not intended to limit the invention. Furthermore, this document is not limited to the foregoing prior art or the invention itself, or to any theory described in the following embodiments. Attached Figure Description

[0045] Figure 1 For LaCo 0.6-x Fe x Ni 0.4 O 3-δ Thermal expansion coefficient diagram with LCN;

[0046] Figure 2 For LaCo 0.6-x Fe x Ni 0.4 O 3-δ LCN and LaSrMnO 3-δ Conductivity diagram;

[0047] Figure 3 This is a schematic diagram of the structure of an automotive oxygen sensor.

[0048] Figure 4 The results of the cyclic response tests for oxygen sensor I and oxygen sensor II;

[0049] Figure 5 Microscopic morphology of the cross-section of the inner electrode and zirconium tube blank of oxygen sensor II;

[0050] Figure 6 The surface microstructure of the internal electrode of oxygen sensor II;

[0051] Figure 7 The XRD pattern of LCN composite with 50wt% NM after heat treatment;

[0052] Figure 8 Thermal expansion coefficient diagrams for LCN, NM, and LCN composites with 20wt% NM, 30wt% NM, and 40wt% NM;

[0053] Figure 9 LCN composites of 20wt% NM, 30wt% NM, 40wt% NM and LaSrMnO 3-δ Conductivity diagram;

[0054] Figure 10 A schematic diagram of the oxygen electrode interface connection layer in a sandwich structure;

[0055] Figure 11 This is a partial structural diagram of a solid oxide battery stack.

[0056] Figure 12 For the use of the sandwich structure LaCo of the present invention0.3 Fe 0.3 Ni 0.4 O 3-δ -LCN-40wt%NM-LaCo 0.3 Fe 0.3 Ni 0.4 O 3-δ The single-cell stack, which serves as the oxygen electrode interface layer, exhibited an open-circuit voltage of 2A cm⁻¹ after 10 thermal cycling tests. -2 The curve showing the change in output power density under current density;

[0057] Figure 13 The open-circuit voltage of a single-cell stack using LCN as the oxygen electrode interface bonding material was measured after eight thermal cycling tests, and its voltage remained constant at 2A cm⁻¹. -2 The curve showing the change in output power density under current density;

[0058] Figure 14 This is a cross-sectional microstructure of a full cell after 10 thermal cycles of a single-cell stack using the sandwich structure oxygen electrode interface connection layer of the present invention.

[0059] Illustration: 100 - Zirconium tube blank; 200 - External electrode; 300 - Internal electrode; 400 - Anti-poisoning protective coating;

[0060] 1-Metallic connector; 2-Oxygen electrode interface bonding layer; 21-LaCo 0.6-x Fe x Ni 0.4 O 3-δ 1-Layer; 22-LCN-NM layer; 3-Single cell; 31-Oxygen electrode layer; 32-Oxygen electrode barrier layer; 33-Electrolyte layer; 34-Hydrogen electrode functional layer; 35-Hydrogen electrode support; 4-Hydrogen electrode interface layer; 5-Sealing material. Detailed Implementation

[0061] The present invention will be further described below with reference to the embodiments. It should be noted that the following embodiments are provided for illustrative purposes only and do not constitute a limitation on the scope of protection of the present invention.

[0062] Unless otherwise specified, the raw materials, reagents, and methods used in the embodiments are all conventional raw materials, reagents, and methods in the art.

[0063] LCN (LaCo) 0.6 Ni 0.4 O 3-δ (This was prepared in the laboratory, and the synthesis method was similar to that in Example 1.)

[0064] Example 1 LaCo 0.6-x Fe x Ni 0.4 O3-δ Preparation of powder materials

[0065] (1) Raw material preparation: Weigh La(NO3)3·6H2O, Co(NO3)2·6H2O, Fe(NO3)3·9H2O, and Ni(NO3)3·6H2O according to the element stoichiometric ratio, and dissolve them in a mixed solution of deionized water and ethanol (volume ratio 1:1) to form a mixed solution with a total metal ion concentration of 0.6 mol / L;

[0066] (2) Coprecipitation reaction: Under stirring conditions, 2 mol / L NH3·H2O was slowly added dropwise to the mixed solution to adjust the pH of the solution to 8.0-8.5 so that the metal ions could be completely precipitated; after stirring for 1 h, the mixture was allowed to stand for 24 h to precipitate and the precursor precipitate was obtained.

[0067] (3) Washing and drying: The precursor precipitate was washed 3-5 times with deionized water and ethanol alternately to remove impurity ions; then the precipitate was placed in a vacuum drying oven at 90℃ and dried for 10h to obtain dried precursor powder.

[0068] (4) Calcination and grinding: The dried precursor powder was placed in a muffle furnace and heated to 400°C at a heating rate of 4°C / min, and held for 3 hours to complete the pre-calcination and remove organic impurities. Then, the temperature was increased to 900°C at a heating rate of 3°C / min and held for 5 hours to complete the calcination and obtain LaCo. 0.6-x Fe x Ni 0.4 O 3-δ Powder; after calcination, the powder is placed in a planetary ball mill, with agate balls as the grinding medium, a ball-to-powder ratio of 5:1, a rotation speed of 350 r / min, and grinding for 24 h to obtain a uniform powder with a particle size of 0.1-0.2 μm.

[0069] LaCo was prepared using the above methods. 0.5 Fe 0.1 Ni 0.4 O 3-δ LaCo 0.4 Fe 0.2 Ni 0.4 O 3-δ LaCo 0.3 Fe 0.3 Ni 0.4 O 3-δ .

[0070] Figure 1 For LaCo 0.6-x Fe x Ni 0.4 O 3-δ The thermal expansion coefficient diagram of LCN shows that its thermal expansion coefficient gradually decreases with increasing Fe doping content.

[0071] Figure 2 For LaCo 0.6-x Fe x Ni 0.4 O 3-δ Compared with the conductivity diagram of LCN, the conductivity first decreases and then increases with increasing Fe doping concentration, but it is still higher than that of LaSrMnO. 3-δ Conductivity of conventional oxygen electrode interface materials.

[0072] Considering both thermal expansion coefficient and electrical conductivity, LaCo is the preferred choice. 0.3 Fe 0.3 Ni 0.4 O 3-δ .

[0073] Example 2: Preparation of Oxygen Sensor

[0074] The structure of the oxygen sensor is as follows Figure 3 As shown, it includes a zirconium tube preform 100 (i.e., the substrate material is yttrium-stabilized zirconium oxide), an inner electrode 300 located inside the zirconium tube preform and an outer electrode 200 located outside the zirconium tube preform. The outer tip of the zirconium tube preform 100 is also provided with an anti-poisoning protective coating 400.

[0075] Oxygen sensor I:

[0076] The preparation method is as follows: 0.2g of Pt powder (particle size 0.3-0.5μm) is mixed with 0.14g of binder to prepare Pt slurry (solid content 60%); the slurry is atomized with 20MPa compressed air for 30s, and the atomized slurry is sprayed onto the inside of the zirconium tube preform to form a 20μm thick annular inner electrode; the zirconium tube preform is placed on the centrifuge disc of a centrifuge and rotated at 1000 rpm to coat the outside of the zirconium tube preform with slurry to form a 20μm thick annular outer electrode; the zirconium tube preform is sintered in a furnace, and after sintering, it is naturally cooled in air to obtain a tubular oxygen sensor I with inner and outer electrodes.

[0077] Oxygen Sensor II:

[0078] The difference from oxygen sensor I is that Pt powder is replaced with LaCo. 0.3 Fe 0.3 Ni 0.4 O 3-δ Powder (particle size 0.1-0.2μm), spray thickness 20μm.

[0079] The oxygen sensor described above was tested as follows:

[0080] The sensor was installed in a sealed test chamber and heated to its operating temperature. During the test, by precisely controlling the gas mixture ratio and maintaining a constant total gas flow rate, the atmosphere was periodically switched between a lean state (λ = 1.1) and a rich state (λ = 0.9), and the sensor output voltage change curve over time was continuously recorded. The output voltage characteristics and dynamic response performance of the oxygen sensor under rich / lean combustion conditions were tested, including the steady-state output voltage (V0.9) in rich and lean states. R / V L ) and the response time for switching between concentrated and dilute states (T) LR / T RL ).

[0081] Where V R and V L T represents the output voltage under rich and poor conditions, respectively. LR T represents the time required for the output voltage to rise from 300mV to 600mV when switching from a rarefied state to a rich state (λ=1.1→0.9). RL This represents the time required for the output voltage to drop from 600mV to 300mV when the atmosphere switches from a rich state to a dilute state (λ=0.9→1.1).

[0082] Figure 4 The results show the cyclic response test results for oxygen sensor I and oxygen sensor II. The concentration-state signal voltage V of oxygen sensor II is also shown. R and the rarefaction signal voltage V L Slightly lower than oxygen sensor I, but the response time T of oxygen sensor II switching from a dilute to a concentrated state is... LR The response time T for switching from a concentrated state to a dilute state RL Both are less than those of oxygen sensor I, indicating that oxygen sensor II has a more sensitive response. Although the response signal of oxygen sensor II is slightly lower than that of oxygen sensor I, from a cost perspective, the perovskite material LaCo... 0.3 Fe 0.3 Ni 0.4 O 3-δ The cost is far lower than that of Pt electrodes. Therefore, LaCo 0.3 Fe 0.3 Ni 0.4 O 3-δ It has the feasibility of replacing Pt electrodes.

[0083] Figure 5 The microstructure of the cross-section of the inner electrode and the zirconium tube blank of the oxygen sensor II is shown. The interface between the two is tightly bonded, without delamination or cracking, indicating that the perovskite material LaCo 0.3 Fe 0.3 Ni 0.4 O 3-δ It exhibits good bonding strength with the zirconium tube preform.

[0084] Figure 6 The microstructure of the inner electrode of oxygen sensor II shows that the electrode surface has uniform particles and no cracks, indicating the use of LaCo. 0.3 Fe 0.3 Ni 0.4 O 3-δ The material exhibits good uniformity as an oxygen sensor electrode, and its thermal behavior is well matched with that of the zirconium tube preform.

[0085] Example 3: Preparation of LCN-NM composite powder material

[0086] (1) Raw material preparation: Weigh Nd(NO3)3·6H2O and Mn(NO3)2·4H2O according to the Nd:Mn molar ratio of 1:1, dissolve them in deionized water to form a mixed solution with a metal ion concentration of 0.6mol / L;

[0087] (2) Complexation reaction: Under continuous heating (oil bath 80-110℃) and stirring, citric acid (CA) and ethylenediaminetetraacetic acid (EDTA) are added to the mixed solution, wherein the molar ratio of total metal ions:CA:EDTA is 1:1.5:1. 2 mol / L NH3·H2O is added to the mixed solution to adjust the pH to 8-9, ensuring complete dissolution of EDTA. The solution is stirred continuously at 80-110℃ for 6-10 h to form a dry gel.

[0088] (3) Preparation of precursor: The obtained dry gel was dried in an oven at 240℃ for 6-8 hours to obtain a dry and fluffy precursor powder;

[0089] (4) Calcination: The dried precursor powder was placed in a muffle furnace and heated to 400°C at a heating rate of 4°C / min, and held for 3 hours to complete the pre-calcination and remove organic impurities. Then, the temperature was increased to 1100°C at a heating rate of 3°C / min and held for 5 hours to complete the calcination and obtain NdMnO. 3-δ (NM) powder;

[0090] (5) Ball milling: NM powder with a mass ratio of 20-50wt% and LCN (i.e., LCN:NM mass ratio = 80-50: 20-50) are placed in a planetary ball mill. Anhydrous ethanol with a volume of 1 / 2 of the ball mill jar is added as the dispersion medium. Agate balls are used as the grinding medium. The ball-to-material ratio is 5:1. The rotation speed is 350r / min. After ball milling for 24h, the mixture is placed in an oven to dry, and a uniformly mixed powder with a particle size of 0.2-1.5μm is obtained.

[0091] The homogeneously mixed powder was further heat-treated to evaluate its chemical compatibility.

[0092] Figure 7The XRD patterns of LCN composites with 50wt% NM after heat treatment are shown. The heat treatment conditions for the samples from top to bottom were 800℃ for 5 h, 850℃ for 5 h, and 1000℃ for 5 h, respectively. Comparison with the standard PDF spectra of LCN and NM samples revealed no new phase formation, indicating good chemical compatibility between LCN and the negatively thermally expanding phase NM.

[0093] Figure 8 The thermal expansion coefficients of LCN, NM, and LCN composites with 20wt%, 30wt%, and 40wt% NM are shown. By introducing the negative thermal expansion phase NM, the thermal expansion coefficient of LCN has been significantly reduced.

[0094] Figure 9 The conductivity of LCN composites with 20wt%, 30wt%, and 40wt% NM was measured. Although the conductivity of the oxygen electrode interface material decreased after incorporating a certain amount of NM, it was still much higher than that of conventional oxygen electrode interface materials (such as LaSrMnO). 3-δ Conductivity of (etc.).

[0095] Considering both thermal expansion coefficient and electrical conductivity, LCN composite with 40wt% NM is preferred.

[0096] Example 4

[0097] The number of cells per cell is 1 layer, according to Figure 11 Structure fabrication of fuel cell stacks:

[0098] Fuel cell stack I: Metal interconnect (Fe-16Cr alloy) - Oxygen electrode interface connection layer I (sandwich structure LaCo) 0.3 Fe 0.3 Ni 0.4 O 3-δ -LCN-40wt%NM-LaCo 0.3 Fe 0.3 Ni 0.4 O 3-δ - Single cell (LSCF-GDC|GDC|8YSZ|NiO-8YSZ, where the NiO-8YSZ support is 0.7mm thick, the 8YSZ electrolyte layer is 8μm thick, the GDC barrier layer is 4μm thick, the oxygen electrode LSCF-GDC (from Zhejiang Hydrogen Power Co., Ltd.) is 20μm thick) - Hydrogen electrode interface layer Ni (3μm thick) - Metal connector (Fe-16Cr alloy);

[0099] The preparation method is as follows:

[0100] LaCo 0.3 Fe 0.3 Ni 0.4 O 3-δ Slurry preparation: LaCo 0.3Fe 0.3 Ni 0.4 O 3-δ The powder and binder (4wt% ethyl cellulose and 96wt% terpineol) were mixed to form a slurry with a solid content of 60wt%, and then ground in a high-energy ball mill for 1 hour to ensure that the slurry was uniformly mixed and had good fluidity.

[0101] Preparation of LCN-40wt% NM composite slurry: LCN and NM were mixed at a mass ratio of 6:4. Then, the powder and binder (4wt% ethyl cellulose and 96wt% terpineol) were mixed to prepare a slurry with a solid content of 60wt.%. The slurry was then ground in a high-energy ball mill for 1 hour to ensure that the slurry was mixed evenly and had good fluidity.

[0102] LaCo was printed using screen printing technology. 0.3 Fe 0.3 Ni 0.4 O 3-δ The slurry was coated onto the surface of the oxygen electrode of a single cell, and the temperature was increased to 800℃ in air at a rate of 3℃ / min to complete the in-situ sintering of the powder, ultimately forming a LaCo layer with a thickness of 5μm. 0.3 Fe 0.3 Ni 0.4 O 3-δ Layer. Using the same method, LCN-40wt% NM composite slurry is then sequentially coated to form a 10μm LCN-40wt% NM layer, followed by LaCo coating. 0.3 Fe 0.3 Ni 0.4 O 3-δ The slurry forms 5μm LaCo 0.3 Fe 0.3 Ni 0.4 O 3-δ The oxygen electrode interface connection layer is obtained by sequentially connecting the stack structure.

[0103] Fuel Cell Stack II:

[0104] The difference from stack I is that oxygen electrode interface bonding layer I is replaced with oxygen electrode interface bonding layer II (20μm LCN-40wt% NM layer).

[0105] Fuel Cell Stack III:

[0106] The difference from stack I is that oxygen electrode interface bonding layer I is replaced with oxygen electrode interface bonding layer III (20 μm LaCo). 0.3 Fe 0.3 Ni 0.4 O 3-δ layer).

[0107] Fuel Cell IV:

[0108] The difference from stack I is that the oxygen electrode interface bonding layer I is replaced with oxygen electrode interface bonding layer IV (a 20 μm LCN layer).

[0109] fuel cell stack V:

[0110] The difference from stack I is that the oxygen electrode interface bonding layer I is replaced with an oxygen electrode interface bonding layer V (20 μm La). 0.9 Sr 0.1 MnO 3-δ layer).

[0111] Fuel cell stack VI:

[0112] The difference from stack I is that the oxygen electrode interface bonding layer I is replaced with oxygen electrode interface bonding layer VI (10μm LCN-40% NM-5μm LaCo). 0.3 Fe 0.3 Ni 0.4 O 3-δ -10μm LCN-40% NM).

[0113] Thermal cycling stability tests were conducted on fuel cell stacks I through VI, with a thermal cycling temperature range of 300-750℃. The test temperature was 750℃, and the corresponding current density for the power density was 0.5 A cm⁻¹. -2 .

[0114] The results are shown in Table 1 below.

[0115] Table 1

[0116]

[0117] Figure 12 To use the sandwich structure LaCo 0.3 Fe 0.3 Ni 0.4 O 3-δ -LCN-40wt%NM-LaCo 0.3 Fe 0.3 Ni 0.4 O 3-δ The single-cell stack (stack I), using the oxygen electrode interface material, exhibits its open-circuit voltage versus output power density after 10 thermal cycles. The test temperature was 750℃, the thermal cycling temperature range was 300-750℃, and the corresponding current density for the power density was 2A cm⁻¹. -2 After 10 thermal cycles, the open-circuit voltage of the fuel cell stack remained relatively stable during the thermal cycling process. In comparison, its voltage at 2A cm⁻¹ remained relatively stable. -2 The power density stability under current density is significantly improved, indicating that improving the thermal expansion matching of the oxygen electrode interface material can effectively enhance the thermal cycling stability of the fuel cell stack. Figure 13 This is a curve showing the open-circuit voltage versus output power density of a single-cell fuel cell stack (stack IV) using LCN as the oxygen electrode interface material after 8 thermal cycles. The test temperature was 750℃, the thermal cycling temperature range was 300-750℃, and the current density corresponding to the power density was 2A cm⁻¹. -2 The open-circuit voltage of the single-cell stack remained relatively stable during eight thermal cycles, but its voltage remained relatively stable at 2A cm⁻¹. -2 The power density decays significantly under current density conditions.

[0118] Figure 14 The image shows the cross-sectional microstructure of a single-cell stack using the sandwich structure oxygen electrode interface connection layer of the present invention after 10 thermal cycles. After thermal cycling, the layers of the battery are well bonded and no delamination is observed, indicating that the battery using this structure has good thermal cycling stability.

[0119] The above embodiments are merely illustrative of the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein, without departing from the spirit and substance defined by the claims of the present invention; and such modifications or substitutions are still within the scope defined by the claims of the present invention.

Claims

1. An oxygen electrode interface bonding layer, characterized in that, The oxygen electrode interface bonding layer includes a LaCo layer facing the surface of the metal connector. 0.6-x Fe x Ni 0.4 O 3-δ LaCo layer facing the oxygen electrode surface of a single cell 0.6-x Fe x Ni 0.4 O 3-δ The layer, and the LCN-NM layer between the two; The LaCo 0.6-x Fe x Ni 0.4 O 3-δ Layers made of LaCo 0.6-x Fe x Ni 0.4 O 3-δ Material composition, where 0.1 ≤ x ≤ 0.4; The LCN-NM layer is made of LaCo 0.6 Ni 0.4 O 3-δ and NdMnO 3-δ It is composed of composite materials, in which NdMnO 3-δ The material's mass percentage is 20-50 wt%; LaCo for metal connector surface and single cell oxygen electrode surface 0.6-x Fe x Ni 0.4 O 3-δ The thickness of each layer is 3-6 μm; the thickness of the LCN-NM layer is 10-20 μm. LaCo 0.6-x Fe x Ni 0.4 O 3-δ The material has a particle size of 0.1-0.2 μm; LaCo 0.6 Ni 0.4 O 3-δ and NdMnO 3-δ The particle size of the composite material is 0.2-1.5 μm.

2. The oxygen electrode interface bonding layer according to claim 1, characterized in that, LaCo 0.6-x Fe x Ni 0.4 O 3-δ 0.2≤x≤0.3 in the material; LaCo 0.6 Ni 0.4 O 3-δ and NdMnO 3-δ In composite materials, NdMnO 3-δ The material accounts for 40 wt% of the total mass.

3. The oxygen electrode interface bonding layer according to claim 1, characterized in that, LaCo for metal connector surface and single cell oxygen electrode surface 0.6-x Fe x Ni 0.4 O 3-δ The thickness of each layer is 5 μm, and the thickness of the LCN-NM layer is 10 μm.

4. A solid oxide battery stack, characterized in that, The method includes providing an oxygen electrode interface connection layer as described in any one of claims 1-3 between the oxygen electrode and the metal connector of a single cell.

5. The solid oxide battery stack according to claim 4, characterized in that, The solid oxide battery stack includes a repeating structural unit consisting of a metal connector, an oxygen electrode interface layer, a single cell, a hydrogen electrode interface layer, and the metal connector.

Images