Asymmetric solid oxide fuel cell / electrolytic cell connector assembly, preparation method and solid oxide fuel cell / electrolytic cell

Abstract

The invention provides an asymmetric solid oxide fuel cell / electrolytic cell connector assembly, a preparation method and a solid oxide fuel cell / electrolytic cell, the connector assembly is composed of an air side functional layer and a fuel side functional layer, the air side functional layer and the fuel side functional layer are both made of perovskite type rare earth chromate, and the air side functional layer and the fuel side functional layer are made of perovskite type rare earth chromate. The chemical composition is represented as La1-xAxCr1-y-zByCzO3-delta (0.2 < = x < = 0.4, 0 < = y < = 0.8, and 0 < = z < = 0.1); wherein A is selected from Ca or Sr, B is selected from Co or Fe, and C is selected from Zn, Ti or Cu; the sum of the doping amount of B and C in the air side functional layer is not lower than the sum of the doping amount of B and C in the fuel side functional layer; compared with the prior art, the asymmetric solid oxide fuel cell / electrolytic cell connector assembly provided by the invention has the advantages of excellent thermomechanical matching property and structural reliability, high conductivity, low ohmic loss, good sintering activity and preparation process compatibility, and good industrial application prospect.

Description

Technical Field

[0001] This invention relates to the field of solid oxide fuel cell / electrolyte technology, and particularly to an asymmetric solid oxide fuel cell / electrolyte connector assembly, its preparation method, and a solid oxide fuel cell / electrolyte. Background Technology

[0002] Solid oxide fuel cells (SOFCs) offer advantages such as high energy conversion efficiency, high power density, and low pollution, while also demonstrating significant advantages in the flexible and efficient utilization of hydrocarbon fuels. Therefore, they are considered a highly promising power generation device. Theoretically, a single SOFC cell has a voltage of only 1.2 V. To achieve the kW or MW power output required for engineering applications, multiple single cells need to be connected in series or parallel to form a stack. Solid oxide fuel cells (SOFCs) and solid oxide electrolyzers (SOECs) are reversible applications of the same device under different operating modes, collectively referred to as solid oxide batteries (SOCs). The connector is one of the most critical core components in a solid oxide fuel cell / electrolyzer. Its function is to transfer electrons between adjacent anodes and cathodes and to isolate fuel gas from oxygen, which is a key factor in ensuring the long-term stable operation of the stack.

[0003] In actual service environments, the connector is exposed to both high-temperature oxidizing and reducing atmospheres. The significant oxygen partial pressure difference between the oxidant and the fuel gas, resulting in a chemical potential gradient, severely limits the range of connector materials to be selected. Its performance requirements are the most stringent among SOC components: (i) high electronic conductivity and negligible ionic conductivity; (ii) excellent chemical and structural stability under both oxidizing and reducing atmospheres; (iii) extremely low oxygen and hydrogen permeability; (iv) matching coefficient of thermal expansion with adjacent components and good compatibility; and (v) high mechanical strength and thermal conductivity.

[0004] To date, the developed connectors can be broadly categorized into two types: metallic connectors and ceramic connectors. Metallic connectors, such as chromium-based alloys, nickel-based alloys, and ferritic stainless steel, offer significant advantages in low- and medium-temperature planar fuel cell stacks due to their lower cost and excellent electrical and thermal conductivity at medium and low temperatures. However, these metallic connectors are unsuitable for high-temperature segmented tandem tube fuel cell stacks because they suffer from numerous problems in high-temperature environments, including insufficient high-temperature oxidation resistance, severe interfacial reactions, and cathode poisoning caused by the volatilization of Cr(VI) species. Ceramic connectors, on the other hand, have become the preferred connector material for high-temperature segmented tandem tube SOC fuel cell stacks due to their excellent electronic conductivity and good thermal stability under oxidizing / reducing atmospheres, as well as their good compatibility with other battery components in terms of phase, microstructure, and thermal expansion.

[0005] Currently, the most widely used ceramic interconnects mainly include La-doped SrTiO3 (LST) and Sr or Ca-doped LaCrO3 (LSC or LCC). However, due to the intrinsic conductivity of these two types of materials, their conductivity on the cathode / anode sides differs by orders of magnitude during actual service. Specifically, LST has extremely low conductivity in the cathode atmosphere, while LSC or LCC has low conductivity in the anode atmosphere. Therefore, when using a single ceramic interconnect, the overall output performance of the fuel cell stack is severely limited by the low conductivity of the interconnect in one atmosphere. In addition, LaCrO3-based materials have poor sintering activity. LSC typically requires a densification temperature exceeding 1700 °C, and although LCC has improved somewhat, it still needs to be sintered at around 1600 °C to achieve the required density. When sintered in thin film form, the sintering temperature is even higher. These stringent sintering conditions further increase the difficulty of constructing the battery and fuel cell stack.

[0006] Therefore, the development of novel ceramic connector materials and their structural design that combine good sintering performance, high conductivity and stability in both oxidizing and reducing atmospheres are crucial for the output performance and long-term operational stability of high-temperature tubular segmented series SOC stacks. Summary of the Invention

[0007] The present invention provides an asymmetric solid oxide fuel cell / electrolyte connector assembly, a preparation method thereof, and a solid oxide fuel cell / electrolyte, to solve at least one of the technical problems mentioned in the background art above.

[0008] The specific details of the invention are as follows: In a first aspect, the present invention provides an asymmetric solid oxide fuel cell / electrolyte connector assembly, the connector assembly comprising an air-side functional layer and a fuel-side functional layer, wherein both the air-side functional layer and the fuel-side functional layer are composed of perovskite-type rare earth chromates, the chemical composition of which is expressed as: La 1-x A x Cr 1-y-z B y C z O 3-δ (0.2≤x≤0.4, 0≤y≤0.8, 0≤z≤0.1); where A is selected from Ca or Sr, B is selected from Co or Fe, C is selected from Zn, Ti or Cu, and δ represents the non-stoichiometric part of oxygen; The sum of the doping amounts of B and C in the air-side functional layer is not less than the sum of the doping amounts of B and C in the fuel-side functional layer.

[0009] Optionally, the air-side functional layer and the fuel-side functional layer are composed of La. 1-x Sr x Cr 1-y-z Fe yTi z O 3-δ (0.2≤x≤0.4, 0≤y≤0.8, 0≤z≤0.1).

[0010] Optionally, the amount of Fe doping in the air-side functional layer is higher than the amount of Fe doping in the fuel-side functional layer, and the amount of Ti doping in the air-side functional layer is lower than the amount of Ti doping in the fuel-side functional layer.

[0011] Optionally, the air-side functional layer and the fuel-side functional layer are composed of La. 1-x Sr x Cr 1-y-z Co y Cu z O 3-δ (0.2≤x≤0.4, 0≤y≤0.1, 0≤z<0.05).

[0012] Optionally, the amount of Co doping in the air-side functional layer is not less than the amount of Co doping in the fuel-side functional layer, and the amount of Cu doping in the air-side functional layer is higher than the amount of Cu doping in the fuel-side functional layer.

[0013] Optionally, the air-side functional layer and the fuel-side functional layer are composed of La. 1-x Ca x Cr 1-y-z Co y Zn z O 3-δ (0.2≤x≤0.4, 0≤y≤0.1, 0≤z<0.05).

[0014] Optionally, the amount of Co doping in the air-side functional layer is not less than the amount of Co doping in the fuel-side functional layer, and the amount of Zn doping in the air-side functional layer is higher than the amount of Zn doping in the fuel-side functional layer.

[0015] Optionally, the conductivity (σ) of the air-side functional layer in an air atmosphere at 800 °C AS The electrical conductivity (σ) of the fuel-side functional layer in air at 800 °C FS Satisfy: σ AS ≥ 1.1σ FS .

[0016] Optionally, the electrical conductivity (σ) of the fuel-side functional layer in a hydrogen atmosphere at 800 °C is... FS The conductivity (σ) of the air-side functional layer in a hydrogen atmosphere at 800 °C AS Satisfy: σ FS ≥ 1.1σ AS .

[0017] Optionally, the coefficient of thermal expansion (CTE) of the air-side functional layer AS The coefficient of thermal expansion (CTE) of the fuel-side functional layer FS Satisfying: CTE AS With CTE FS Difference ≤ 3 × 10 -6 K -1 .

[0018] In a second aspect, the present invention provides a method for preparing the asymmetric solid oxide fuel cell / electrolyte connector assembly described in the first aspect above, wherein the connector assembly is obtained by the following preparation method: According to the preset stoichiometric ratio, the metal precursor salts required to form the air-side functional layer and the fuel-side functional layer are weighed out respectively, dissolved, gelled, calcined and particle size homogenized to obtain the target phase powders corresponding to each functional layer. The target phase powders corresponding to each functional layer are laid in layers using a layer-by-layer powder spreading method. After dry pressing, a green body of the laminated structure connector is obtained. The green body of the laminated structure connector is then subjected to a first high-temperature sintering to obtain the connector assembly; or The target phase powders corresponding to each functional layer are mixed with an organic carrier to form a slurry. The two slurries are screen printed layer by layer to obtain a green body of the stacked structure connector. The green body of the stacked structure connector is then subjected to a second high-temperature sintering to obtain the connector assembly.

[0019] Optionally, the step of weighing the metal precursor salts required to form the air-side functional layer and the fuel-side functional layer according to a preset stoichiometric ratio, dissolving them, and then performing gelation, calcination, and particle size homogenization treatment includes: The metal precursor salts required for the air-side functional layer and the metal precursor salts required for the fuel-side functional layer are dissolved to form AS mixed solution and FS mixed solution, respectively. Citric acid and ethylene glycol are then added to the two mixed solutions, and the mixture is heated and stirred until a gel-like substance is formed. After drying, a dry gel is obtained. The homogenization process is completed after the dry gel is ground, calcined, and ball-milled.

[0020] Optionally, in the mixed solution system, the concentration ratio of citric acid, ethylene glycol, and total metal ions is 1:1:1.

[0021] Optionally, the calcination temperature is 700-900 ℃ and the time is 5-10 h.

[0022] Optionally, the particle size of the target phase powder is 0.05-5 μm.

[0023] Optionally, the pressure of the dry press is 100-300 MPa; The first high-temperature sintering temperature is 1300-1400 ℃, and the time is 2-4 h.

[0024] Optionally, the organic carrier is selected from at least one of ethanol, ethyl acetate, α-terpineol, ethyl cellulose, castor oil, polyvinylpyrrolidone, triethanolamine, polyvinyl butyral, and polyethylene glycol; The mass ratio of the target phase powder to the organic carrier is 1:1-1.3; The second high-temperature sintering temperature is 1350-1450 ℃, and the time is 4-8 h.

[0025] Thirdly, the present invention provides an asymmetric solid oxide fuel cell / electrolyte, comprising the asymmetric solid oxide fuel cell / electrolyte connector assembly described in the first aspect.

[0026] This invention provides an asymmetric solid oxide fuel cell / electrolyte connector assembly, comprising an air-side functional layer and a fuel-side functional layer. Both the air-side and fuel-side functional layers are composed of perovskite-type rare-earth chromates, with the chemical composition expressed as: La. 1-x A x Cr 1-y-z B y C z O 3-δ (0.2≤x≤0.4, 0≤y≤0.8, 0≤z≤0.1); wherein A is selected from Ca or Sr, B is selected from Co or Fe, and C is selected from Zn, Ti, or Cu; the sum of the doping amounts of B and C in the air-side functional layer is not less than the sum of the doping amounts of B and C in the fuel-side functional layer; compared with the prior art, the present invention has the following advantages: Excellent thermomechanical matching and structural reliability: This invention innovatively provides an asymmetric stacked structure connector composed of an air-side functional layer and a fuel-side functional layer through composition optimization and structural design. Its gradient-varying CTE can match the thermal expansion coefficient (CTE) of the fuel-side functional layer with that of the adjacent fuel electrode (anode), and at the same time match the CTE of the air-side functional layer with that of the adjacent air electrode (cathode). This can effectively alleviate the internal thermal stress generated by thermal cycling during battery preparation and operation, greatly reduce the risk of interface delamination, cracking or bending, and thus significantly improve the structural integrity and long-term operational reliability of the battery stack. High electrical conductivity and low ohmic loss: The asymmetric stacked interconnect structure provided by this invention is tailored to the actual service environment of oxidizing / reducing dual atmospheres. The fuel-side functional layer uses a material with high electronic conductivity in a reducing atmosphere, while the air-side functional layer uses a material with high electronic conductivity in an oxidizing atmosphere. This design enables the stacked interconnect structure to exhibit excellent conductivity in actual service environments, significantly reducing ohmic losses during current transmission, thereby contributing to improved power output and energy conversion efficiency of the entire solid oxide fuel cell / electrolyte.

[0027] Excellent sintering activity and compatibility with fabrication processes: The specific doped system connector material developed in this invention exhibits high sintering activity, enabling full densification at 1400 °C or lower. This characteristic allows the connector to be fabricated in a single step with the electrolyte layer (such as YSZ, GDC) and electrode layer via a co-sintering process. This method is suitable for fabricating high-strength, high-performance multi-section tandem SOC stacks and has promising prospects for industrial application. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 The microstructure and interface bonding of the connector assembly provided in the embodiment of the present invention are shown. Figure 2 The microstructure and interface bonding of a connector assembly provided in another embodiment of the present invention are shown. Figure 3 The microstructure and interface bonding of a connector assembly provided in another embodiment of the present invention are shown. Figure 4 The microstructure of the connector assembly provided in Comparative Examples 1-2 of the present invention is shown. Figure 5 The microstructure of the connector assembly provided in Comparative Example 3 of the present invention is shown. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention. Furthermore, all other embodiments obtained by those skilled in the art without inventive effort are within the protection scope of the present invention.

[0031] Specific experimental steps or conditions are not specified in the embodiments; they can be performed according to the conventional experimental steps or conditions described in the prior art. Reagents and other instruments used, unless otherwise specified, are all commercially available conventional reagent products. Furthermore, the accompanying drawings are merely illustrative diagrams of the embodiments of the present invention and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and therefore, repeated descriptions of them will be omitted. Some block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities.

[0032] Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of this specification.

[0033] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0034] Solid oxide fuel cells / electrolytes, as efficient and clean energy conversion devices, rely heavily on the electrical performance and reliability of their interconnects for stack performance. Currently, the most widely used ceramic interconnects include La-doped SrTiO3 (LST) and Sr or Ca-doped LaCrO3 (LSC or LCC). However, these materials all have significant drawbacks that hinder the performance improvement and industrialization of SOC stacks. 1) Low conductivity and high ohmic loss: Ceramic connectors actually operate in different atmospheres on the cathode and anode sides (oxidizing air atmosphere on the cathode side and reducing fuel atmosphere on the anode side). However, due to the intrinsic conductivity of LST, LSC, and LCC, the conductivity of these materials differs by orders of magnitude on both the cathode and anode sides. Specifically, LST has extremely low conductivity in the cathode atmosphere, while LSC or LCC has relatively low conductivity in the anode atmosphere. Therefore, when a single ceramic connector is used, this low conductivity in one atmosphere will lead to a significant increase in ohmic loss during current transmission, severely limiting the overall power output and energy conversion efficiency of the fuel cell stack.

[0035] 2) High sintering temperature and high manufacturing difficulty: LaCrO3-based materials have poor sintering activity. LSCs typically require densification temperatures exceeding 1700 ℃, and LCCs also need to be sintered at around 1600 ℃ to achieve the required density. When sintered in thin film form, the sintering temperature is even higher. These stringent sintering conditions not only lead to a significant increase in equipment energy consumption and production costs, but also significantly increase the difficulty of integrated co-sintering of batteries. For example, excessively high sintering temperatures can cause coarsening of Ni particles in Ni-based anodes, insufficient porosity in porous electrodes, and exacerbate unfavorable interfacial reactions between connectors and adjacent components. 3) Mismatched coefficients of thermal expansion and poor structural reliability: The SOC needs to undergo multiple high-temperature thermal cycles during its fabrication and operation. When a single structural connector is used, its CTE differs from that of the adjacent components on both sides, making it impossible to achieve a high degree of matching with the components on both sides simultaneously. This can lead to significant thermal stress between layers, easily causing interface delamination, cracking, or connector bending, severely shortening the long-term operating life of the fuel cell stack.

[0036] To address the three core problems of existing SOC ceramic connectors—low electrical conductivity, high sintering temperature, and mismatched coefficients of thermal expansion—this invention aims to provide an asymmetric multilayered connector structure that combines excellent comprehensive characteristics such as low-temperature densification, adaptation to thermal expansion properties, and high electrical conductivity under both oxidizing and reducing atmospheres. Simultaneously, it provides a process-compatible preparation method and a battery stack including the asymmetric solid oxide fuel cell / electrolyte connector assembly, ultimately improving the power output, structural reliability, and industrialization potential of the SOC stack. Specific implementation methods are as follows: In a first aspect, the present invention provides an asymmetric solid oxide fuel cell / electrolyte connector assembly, the connector assembly comprising an air-side functional layer and a fuel-side functional layer, wherein both the air-side functional layer and the fuel-side functional layer are composed of perovskite-type rare earth chromates, the chemical composition of which is expressed as: La 1-x A x Cr 1-y-z B y C z O3-δ (0.2≤x≤0.4, 0≤y≤0.8, 0≤z≤0.1); where A is selected from Ca or Sr, B is selected from Co or Fe, and C is selected from Zn, Ti, or Cu; The sum of the doping amounts of B and C in the air-side functional layer is not less than the sum of the doping amounts of B and C in the fuel-side functional layer.

[0037] In specific implementation, the connector assembly provided by this invention is an asymmetric stacked structure, breaking through the traditional design concept of a single homogeneous connector. The connector is divided into two functional layers: an air side and a fuel side, to adapt to the atmospheres on both sides. Specifically, the connector consists of an air-side functional layer (facing the SOC cathode, in contact with an oxidizing air atmosphere) and a fuel-side functional layer (facing the SOC anode, in contact with a reducing fuel atmosphere). Both functional layers are based on perovskite-type rare earth chromate design. Through element doping and composition gradient control, the performance customization of one side adapting to an oxidizing atmosphere and the other side adapting to a reducing atmosphere is achieved.

[0038] Specifically, both functional layers use perovskite-type rare-earth chromate (LaCrO3-based) as the substrate. By introducing dopants with unique electronic structures and chemical properties into specific lattice positions, the conductivity, thermal expansion coefficient, and other properties of the interconnect material can be flexibly controlled while ensuring high-temperature stability. The chemical formula of both functional layers is unified as La. 1- x A x Cr 1-y-z B y C z O 3-δ (0.2≤x≤0.4, 0≤y≤0.8, 0≤z≤0.1), where: A is an alkaline earth metal element, selected from Ca or Sr, which endows LaCrO3 with good electronic conductivity and sinterability; B and C are one or more of the transition metal elements Ti, Fe, Co, Cu, and Zn, which are used to optimize electronic conductivity, improve sintering activity and control the coefficient of thermal expansion.

[0039] This invention addresses the low conductivity issue exhibited by a single interconnect in either the cathode or anode atmosphere by controlling the B / C doping content in the two functional layers to achieve differentiated customization of conductivity. Through a layered design, the two functional layers are adapted to oxidizing (air) and reducing (fuel) atmospheres respectively; specifically, the sum of the B and C doping amounts (y+z) in the air-side functional layer is not less than the sum of the B and C doping amounts (y+z) in the fuel-side functional layer. At the typical SOC operating temperature (800 °C), the conductivity (σ) of the air-side functional layer in an air atmosphere at 800 °C is... AS The electrical conductivity (σ) of the fuel-side functional layer in air at 800 °C FS Satisfy: σ AS≥ 1.1 σ FS This ensures that the air-side functional layer conducts electricity efficiently in an oxidizing atmosphere; and that the fuel-side functional layer maintains high conductivity (σ) in a hydrogen atmosphere at 800 °C. FS The conductivity (σ) of the air-side functional layer in a hydrogen atmosphere at 800 °C AS Satisfy: σ FS ≥ 1.1 σ AS This ensures that the fuel-side functional layer conducts electricity efficiently in a reducing atmosphere.

[0040] Specifically, this invention adjusts the B / C doping content in the functional layers on both sides to reduce the coefficient of thermal expansion (CTE) of the air-side functional layer. AS ) and the coefficient of thermal expansion of the fuel-side functional layer (CTE) FS Satisfying: CTE AS With CTE FS Difference ≤ 3 × 10 -6 K -1 Simultaneously, by adjusting the doping content, the CTE of the air-side functional layer can be highly matched with that of the cathode, and the CTE of the fuel-side functional layer can be highly matched with that of the anode. This effectively alleviates interlayer thermal stress during thermal cycling and prevents interface delamination, cracking, or bending of the connectors.

[0041] In some embodiments, for the Sr-Fe-Ti doped system on a LaCrO3 matrix, the composition of the air-side functional layer and the fuel-side functional layer is determined to be La 1-x Sr x Cr 1-y-z Fe y Ti z O 3-δ (0.2≤x≤0.4, 0≤y≤0.8, 0≤z≤0.1). Among them, Sr and Fe doping can significantly improve electronic conductivity; Ti doping can improve the conductivity on the reducing atmosphere side while suppressing ionic conductivity, balancing the coefficient of thermal expansion, making the CTE of the fuel-side functional layer close to that of the anode (Ni-YSZ), and relieving thermal stress.

[0042] Furthermore, the Fe doping amount in the air-side functional layer is higher than the Fe doping amount in the fuel-side functional layer, and the Ti doping amount in the air-side functional layer is lower than the Ti doping amount in the fuel-side functional layer.

[0043] For the Sr-Fe-Ti doped system on the LaCrO3 matrix, the Fe and Ti doping amounts are inversely distributed on both sides of the functional layers (high Fe and low Ti on the air side; low Fe and high Ti on the fuel side). The high Fe content on the air side increases the electron-hole concentration through an electron compensation mechanism, thereby improving the electronic conductivity under an oxidizing atmosphere; the high Ti content on the fuel side... 4+ →Ti3+ The reduction process improves the electronic conductivity under a reducing atmosphere, while suppressing the ionic conductivity and CTE increase caused by the introduction of oxygen vacancies due to low-valence ion doping. This makes the fuel-side CTE more compatible with the anode, reducing the risk of thermal cycling cracking.

[0044] In some embodiments, the present invention targets a Sr-Co-Cu doped system on a LaCrO3 matrix. The determined composition of the air-side functional layer and the fuel-side functional layer is La. 1-x Sr x Cr 1-y-z Co y Cu z O 3-δ (0.2≤x≤0.4, 0≤y≤0.1, 0≤z<0.05). Both Co and Cu can significantly improve sintering activity; their synergistic effect allows LSCs to be densified at 1400 ℃ (the densification temperature of LSCs typically exceeds 1700 ℃), and also improves electronic conductivity. The amount of Co doping should not be too high, as excessive amounts will impair the mechanical properties of the linker and may induce Co... 3+ The spin-state transition leads to a sharp increase in the coefficient of thermal expansion. Furthermore, Cu doping can balance the coefficient of thermal expansion.

[0045] Furthermore, the amount of Co doping in the air-side functional layer is not less than the amount of Co doping in the fuel-side functional layer, and the amount of Cu doping in the air-side functional layer is higher than the amount of Cu doping in the fuel-side functional layer.

[0046] For the Sr-Co-Cu doped system on the LaCrO3 matrix, the total Co and Cu doping concentration in the air-side functional layer is higher than that in the fuel-side functional layer. This can increase the electron-hole concentration through an electronic compensation mechanism, thereby improving the electronic conductivity under oxidizing atmospheres. Furthermore, the total Co and Cu doping concentration in the fuel-side functional layer is lower than that in the air-side functional layer, avoiding excessive Cr... 4+ The reduction-induced decrease in electron-hole concentration, along with the accompanying generation of additional oxygen vacancies, can serve as scattering centers for electrons and holes, reducing the electronic conductivity loss of the interconnect under reducing atmospheres. The controlled Co and Cu doping levels in the functional layers on both sides allow the asymmetric interconnect assembly to exhibit excellent conductivity in actual service environments. Simultaneously, a higher Cu doping level on the air side can suppress Co... 3+ The spin state transition neutralizes the increase in the coefficient of thermal expansion.

[0047] In some embodiments, the present invention addresses the Ca-Co-Zn doped system on a LaCrO3 matrix, and the composition of the air-side functional layer and the fuel-side functional layer is determined to be La. 1-x Ca x Cr1-y-z Co y Zn z O 3-δ (0.2≤x≤0.4, 0≤y≤0.1, 0≤z<0.05). Among these, Ca-doped LaCrO3 exhibits superior sintering performance compared to Sr-doped LaCrO3. Both Co and Zn doping can further enhance sintering activity; their synergistic effect allows LCC to achieve densification at ≤1400 ℃ (the densification temperature of LCC is typically around 1600 ℃), and can also improve electronic conductivity. The amount of Co doping should not be too high, as excessive Co doping will impair the mechanical properties of the linker and may induce Co... 3+ The spin-state transition of Zn leads to a sharp increase in the coefficient of thermal expansion; in addition, Zn doping can also suppress Cr volatilization.

[0048] Furthermore, the amount of Co doping in the air-side functional layer is not less than the amount of Co doping in the fuel-side functional layer, and the amount of Zn doping in the air-side functional layer is higher than the amount of Zn doping in the fuel-side functional layer.

[0049] For the Ca-Co-Zn doped system on the LaCrO3 matrix, the total doping concentration of Co and Zn in the air-side functional layer is higher than that in the fuel-side functional layer, which can improve the electronic conductivity under oxidizing atmosphere through an electronic compensation mechanism. Conversely, the total doping concentration of Co and Zn in the fuel-side functional layer is lower than that in the air-side functional layer, avoiding excessive Cr... 4+ The reduction-induced decrease in electron-hole concentration, along with the accompanying generation of additional oxygen vacancies, can serve as scattering centers for electrons and holes, reducing the electronic conductivity loss of the interconnect under reducing atmospheres. The controlled amount of Co and Zn doping in the functional layers on both sides allows the asymmetric interconnect assembly to exhibit excellent conductivity under actual service conditions. Simultaneously, a higher Zn doping level on the air side can suppress Cr volatilization, reduce the poisoning of adjacent components—the cathode—and improve the long-term operational stability of the stack.

[0050] In a second aspect, the present invention provides a method for preparing the asymmetric solid oxide fuel cell / electrolyte connector assembly described in the first aspect above, wherein the connector assembly is obtained by the following preparation method: According to the preset stoichiometric ratio, the metal precursor salts required to form the air-side functional layer and the fuel-side functional layer are weighed out respectively, dissolved, gelled, calcined and particle size homogenized to obtain the target phase powders corresponding to each functional layer. The target phase powders corresponding to each functional layer are laid in layers using a layer-by-layer powder spreading method. After dry pressing, a green body of the laminated structure connector is obtained. The green body of the laminated structure connector is then subjected to a first high-temperature sintering to obtain the connector assembly; or The target phase powder corresponding to each functional layer is mixed with an organic carrier to form a slurry. The two slurries are screen printed layer by layer to obtain a layered structure connector green body. The layered structure connector green body is then subjected to a second high-temperature sintering to obtain the connector assembly.

[0051] In specific implementation, La 1-x Sr x Cr 1-y-z Fe y Ti z O 3-δ Taking the system with (0.2≤x≤0.4, 0≤y≤0.8, 0≤z≤0.1) as an example, the required metal precursor salts can be La(NO3)3·6H2O, Sr(NO3)2, Cr(NO3)3·9H2O, Fe(NO3)3·9H2O, Ti(OC4H9)4; taking La 1-x Sr x Cr 1-y-z Co y Cu z O 3-δ Taking the system (0.2≤x≤0.4, 0≤y≤0.1, 0≤z<0.05) as an example, the required metal precursor salts can be La(NO3)3·6H2O, Sr(NO3)2, Cr(NO3)3·9H2O, Co(NO3)2·6H2O, Cu(NO3)2·3H2O; taking La 1-x Ca x Cr 1-y-z Co y Zn z O 3-δ Taking the system (0.2≤x≤0.4, 0≤y≤0.1, 0≤z<0.05) as an example, the required metal precursor salts can be La(NO3)3·6H2O, Ca(NO3)2·4H2O, Cr(NO3)3·9H2O, Co(NO3)2·6H2O, or Zn(NO3)2·6H2O.

[0052] In specific implementation, the embodiments of the present invention preferably provide two preparation processes: layer-by-layer powder spreading and dry pressing method and screen printing method, to adapt to diverse production needs. Both processes are mature technologies in the ceramic field, require no special equipment, and can be directly connected to existing production lines, thus reducing the industrialization threshold.

[0053] It should be noted that, in addition to the two preparation processes of layer-by-layer powder dry pressing and screen printing, other preparation methods can also be used to obtain the connector, such as thermal spraying, slurry spraying, brushing, impregnation, etc.

[0054] In some embodiments, the step of weighing the metal precursor salts required to form the air-side functional layer and the fuel-side functional layer according to a preset stoichiometric ratio, dissolving them, and then performing gelation, calcination, and particle size homogenization treatment includes: The metal precursor salts required for the air-side functional layer and the metal precursor salts required for the fuel-side functional layer are dissolved to form AS mixed solution and FS mixed solution, respectively. Citric acid and ethylene glycol are then added to the two mixed solutions, and the mixture is heated and stirred until a gel-like substance is formed. After drying, a dry gel is obtained. The homogenization process is completed after the dry gel is ground, calcined, and ball-milled.

[0055] In specific implementation, this invention employs a sol-gel method, using citric acid as a complexing agent to form stable complexes with metal ions. During subsequent calcination, citric acid undergoes a vigorous redox reaction with metal nitrates, releasing a large amount of heat and gas, which facilitates the formation of loose, porous powder. Ethylene glycol acts as a crosslinking and dispersing agent, promoting the formation of a three-dimensional gel network, thereby dispersing and fixing the metal ions. The sol-gel process ensures uniform mixing of metal ions at the atomic level, avoiding the compositional inhomogeneity problems easily caused by solid-phase methods, thus ensuring the consistency of the single-sided functional layer. Furthermore, the gelation process inhibits precursor aggregation, resulting in fine-grained powder particles after calcination and significantly improved sintering activity, laying the foundation for subsequent low-temperature sintering (1300-1450 ℃). Moreover, the aforementioned organic compounds are completely decomposed during subsequent sintering, without affecting the various properties of the synthesized material. This method yields precisely composed, finely granulated, and uniformly distributed linker powders.

[0056] Furthermore, in the mixed solution system, the concentration ratio of citric acid, ethylene glycol, and total metal ions is 1:1:1. At this ratio, the metal ions and citric acid are fully complexed, while the ethylene glycol and citric acid undergo sufficient esterification polymerization.

[0057] Furthermore, the calcination temperature is 700-900 °C, and the time is 5-10 h; temperatures above 700 °C ensure complete decomposition of citric acid and ethylene glycol (decomposition temperature approximately 400-600 °C), preventing residual organic matter from generating gas and causing porosity during subsequent sintering. The selected calcination temperature range is sufficient to form a pure perovskite phase, avoiding insufficient activity during subsequent sintering due to excessively high calcination temperatures.

[0058] Furthermore, if the particle size of the target phase powder is too small, it is prone to agglomeration, leading to uneven density of the green body; if the particle size is too large, the sintering activity is low, requiring higher temperatures for densification. Through extensive experimental research, this invention has shown that after grinding, calcining, and ball milling, the particle size of the target phase powder is maintained at 0.05-5 μm. The 0.05-5 μm target phase powder has a strong sintering driving force, ensuring densification at 1300-1450 ℃. Simultaneously, the powder within this particle size range has good flowability, allowing for the formation of a uniform green body layer during layer-by-layer spreading or screen printing, avoiding voids or cracks between layers, and resulting in uniform grain size after sintering.

[0059] Furthermore, the dry pressing pressure is 100-300 MPa to ensure that the green body density reaches 50%-60% of the theoretical density, laying the foundation for subsequent sintering densification; Furthermore, the first high-temperature sintering temperature is 1300-1400 ℃, and the time is 2-4 h. The sintering temperature of 1300-1400 ℃ is significantly lower than that of LSC and LCC, reducing energy consumption by 30%-40%, and the 2-4 h time can ensure sufficient densification (density > 95%), while avoiding over-sintering that leads to coarse grains and elemental segregation; moreover, this sintering temperature can achieve co-sintering with typical electrolytes (such as GDC and YSZ, sintering temperature 1350-1450 ℃), reducing preparation steps and improving production efficiency.

[0060] Furthermore, the organic carrier is selected from at least one of ethanol, ethyl acetate, α-terpineol, ethyl cellulose, castor oil, polyvinylpyrrolidone, triethanolamine, polyvinyl butyral, and polyethylene glycol; the mass ratio of the target phase powder to the organic carrier is 1:1-1.3; the 1:1-1.3 ratio controls the slurry viscosity at 5000-15000 cP, which is suitable for screen printing (too low viscosity easily leads to ink bleeding, too high viscosity easily leads to screen clogging), and can prepare functional layers with uniform thickness (0.01-0.3 mm).

[0061] Furthermore, the second high-temperature sintering temperature is 1350-1450 ℃, and the time is 4-8 h. The sintering temperature of 1350-1450 ℃ can achieve co-sintering with typical electrolytes (such as GDC and YSZ, with a sintering temperature of 1350-1450 ℃), thereby simplifying the preparation process and making it suitable for industrial applications.

[0062] Thirdly, the present invention provides an asymmetric solid oxide fuel cell / electrolyte, comprising the asymmetric solid oxide fuel cell / electrolyte connector assembly described in the first aspect.

[0063] To enable those skilled in the art to more clearly understand the present invention, the following embodiments are provided to illustrate in detail the asymmetric solid oxide fuel cell / electrolyte connector assembly, preparation method, and solid oxide fuel cell / electrolyte of the present invention.

[0064] Example 1 (1) Preparation of Sr-Fe-Ti doped powder: Air-side functional layer (AS): Select La 0.6 Sr 0.4 Cr 0.4 Fe 0.6 O 3-δ La(NO3)3·6H2O, Sr(NO3)2, Cr(NO3)3·9H2O, and Fe(NO3)3·9H2O were weighed according to the preset stoichiometric ratio. The four metal nitrates were dissolved separately in deionized water, and after complete dissolution, they were mixed to obtain solution A, which was then stirred in an 80 ℃ water bath. The corresponding amounts of citric acid and ethylene glycol were weighed according to the ratio of total metal ions:citric acid:ethylene glycol = 1:1:1. The citric acid was dissolved in deionized water, and after complete dissolution, it was added to solution A. Finally, ethylene glycol was added directly to solution A to obtain solution B (AS mixed solution). Solution B was continuously stirred until the solvent evaporated to form a gel, and then placed in a 200 ℃ oven overnight to obtain a fluffy precursor dry gel. This gel was thoroughly ground and calcined at 800 ℃ for 5 h to obtain a well-crystallized AS layer powder. Finally, the powder was wet-ball-milled for 48 h and dried to achieve particle size uniformity.

[0065] Fuel-side functional layer (FS): Select La 0.6 Sr 0.4 Cr 0.5 Fe 0.4 Ti 0.1 O 3-δ La(NO3)3·6H2O, Sr(NO3)2, Cr(NO3)3·9H2O, Fe(NO3)3·9H2O, and Ti(OC4H9)4 were weighed according to a preset stoichiometric ratio. The four metal nitrates were dissolved separately in deionized water, and after complete dissolution, they were mixed to obtain solution A, which was then stirred in an 80 ℃ water bath. The corresponding amounts of citric acid and ethylene glycol were weighed according to a total metal ion:citric acid:ethylene glycol ratio of 1:1:1. Ti(OC4H9)4 was dissolved in ethylene glycol to obtain solution B. Solution B and citric acid were added sequentially to solution A to obtain solution C (FS mixed solution). Solution C was continuously stirred until the solvent evaporated to form a gel, and then placed in a 200 ℃ oven overnight to obtain a fluffy precursor dry gel. This gel was thoroughly ground and calcined at 800 ℃ for 5 h to obtain a well-crystallized FS layer powder. Finally, the powder was wet-ball-milled for 48 h and dried to achieve particle size uniformity.

[0066] (2) Preparation of laminated connectors 0.25 g of AS and FS layer powders were weighed separately and pressed into circular green bodies with a diameter of 12.7 mm under a pressure of 200 MPa using a layer-by-layer powder spreading method (first spreading FS layer powder, then spreading AS layer powder). The AS / FS layered green bodies were heated to 1400 ℃ at a rate of 2 ℃ / min and sintered for 4 h to obtain a dense and well-bonded integrated structure, i.e., a layered connector.

[0067] (3) Performance testing: According to ISO 23331:2021 "Fine ceramics (advanced ceramics, advanced technical ceramics) — Test method for total electrical conductivity of conductive fine ceramics", the conductivity of AS layer and FS layer samples was tested using the DC four-terminal method. The test temperature was 800 ℃, and the test atmospheres were air, hydrogen, and air / hydrogen dual atmosphere, with a heating rate of 5 ℃ / min. The conductivity test method for AS / FS stacked samples was the same as above, but the test atmosphere was only air / hydrogen dual atmosphere. According to GB / T 16535-2008 "Test Method for Linear Thermal Expansion Coefficient of Fine Ceramics - Top Rod Method", the linear thermal expansion coefficient of AS layer and FS layer samples were tested using a high-temperature vertical dilatometer. The test temperature range was 50-1000 ℃, the test atmosphere was air, the heating rate was 5 ℃ / min, and the sample length was 35 mm.

[0068] According to QB / T 1548-2015 "Method for Determination of Linear Shrinkage Rate of Ceramic Body Clay", the linear shrinkage rate of AS layer, FS layer and AS / FS stacked samples was tested, and the density was evaluated in combination with the microstructure.

[0069] Figure 1 The microstructure and interface bonding of the connector assembly provided in Embodiment 1 of the present invention are shown; for example Figure 1 As shown, the interface area of ​​the stacked interconnect is defect-free and structurally continuous. The FS layer and AS layer are mechanically interlocked after high-temperature sintering to achieve a high-strength bond, which has a certain service reliability. Moreover, the overall morphology of the FS layer and AS layer is free of pores and highly dense, which meets the density requirements of the interconnect in the high-temperature segmented series tubular SOC stack.

[0070] Example 2 (Sr-Co-Cu system) (1) Powder preparation: Air-side functional layer (AS): Select La0.8 Sr 0.2 Cr 0.87 Co 0.1 Cu 0.03 O 3-δ According to the preset stoichiometric ratio, La(NO3)3·6H2O, Sr(NO3)2, Cr(NO3)3·9H2O, Co(NO3)2·6H2O, and Cu(NO3)2·3H2O were weighed. The five metal nitrates were dissolved separately in deionized water, and after complete dissolution, they were mixed to obtain solution A, which was then stirred in an 80 ℃ water bath. The corresponding amounts of citric acid and ethylene glycol were weighed according to the ratio of total metal ions:citric acid:ethylene glycol = 1:1:1. The citric acid was dissolved in deionized water, and after complete dissolution, it was added to solution A. Finally, ethylene glycol was added directly to solution A to obtain solution B (AS mixed solution). Solution B was continuously stirred until the solvent evaporated to form a gel, and then placed in a 200 ℃ oven overnight to obtain a fluffy precursor dry gel. After thorough grinding, it was calcined at 800 ℃ for 5 h to obtain a well-crystallized AS layer powder. Finally, the powder was wet ball-milled for 48 hours and dried to achieve uniform particle size.

[0071] Fuel-side functional layer (FS): Select La 0.8 Sr 0.2 Cr 0.89 Co 0.1 Cu 0.01 O 3-δ Weigh out La(NO3)3·6H2O, Sr(NO3)2, Cr(NO3)3·9H2O, Co(NO3)2·6H2O, and Cu(NO3)2·3H2O according to the preset stoichiometric ratio. The remaining steps are the same as the AS layer powder preparation process.

[0072] (2) Preparation of laminated connectors 0.25 g of AS and FS layer powders were weighed separately and pressed into circular green bodies with a diameter of 12.7 mm under a pressure of 200 MPa using a layer-by-layer powder spreading method (first spreading FS layer powder, then spreading AS layer powder). The AS / FS layered green bodies were heated to 1400 ℃ at a rate of 2 ℃ / min and sintered for 4 h to obtain a dense and well-bonded integrated structure, i.e., a layered connector.

[0073] (3) Performance testing: The performance testing method is the same as in Example 1.

[0074] Figure 2 The microstructure and interface bonding of the connector assembly provided in Embodiment 2 of the present invention are shown; for example Figure 2As shown, the interface area of ​​the stacked interconnect is defect-free and structurally continuous. The FS layer and AS layer are mechanically interlocked after high-temperature sintering to achieve a high-strength bond, which has a certain service reliability. Moreover, the overall morphology of the FS layer and AS layer is free of pores and highly dense, which meets the density requirements of the interconnect in the high-temperature segmented series tubular SOC stack.

[0075] Example 3 (1) Preparation of Ca-Co-Zn doped powder system: Air-side functional layer (AS): Select La 0.8 Ca 0.2 Cr 0.94 Co 0.05 Zn 0.01 O 3-δ According to the preset stoichiometric ratio, La(NO3)3·6H2O, Ca(NO3)2·4H2O, Cr(NO3)3·9H2O, Co(NO3)2·6H2O, and Zn(NO3)2·6H2O were weighed. The five metal nitrates were dissolved separately in deionized water, and after complete dissolution, they were mixed to obtain solution A, which was then stirred in an 80 ℃ water bath. The corresponding amounts of citric acid and ethylene glycol were weighed according to the ratio of total metal ions:citric acid:ethylene glycol = 1:1:1. The citric acid was dissolved in deionized water, and after complete dissolution, it was added to solution A. Finally, ethylene glycol was added directly to solution A to obtain solution B (AS mixed solution). Solution B was continuously stirred until the solvent evaporated to form a gel, and then placed in a 200 ℃ oven overnight to obtain a fluffy precursor dry gel. After thorough grinding, it was calcined at 800 ℃ for 5 h to obtain a well-crystallized AS layer powder. Finally, the powder was wet ball-milled for 48 hours and dried to achieve uniform particle size.

[0076] Fuel-side functional layer (FS): Select La 0.7 Ca 0.3 CrO 3-δ Weigh La(NO3)3·6H2O, Ca(NO3)2·4H2O, and Cr(NO3)3·9H2O according to the preset stoichiometric ratio. The remaining steps are the same as the AS layer powder preparation process.

[0077] (2) Preparation of laminated connectors 0.25 g of AS and FS layer powders were weighed separately and pressed into circular green bodies with a diameter of 12.7 mm under a pressure of 200 MPa using a layer-by-layer powder spreading method (first spreading FS layer powder, then spreading AS layer powder). The AS / FS layered green bodies were heated to 1400 ℃ at a rate of 2 ℃ / min and sintered for 4 h to obtain a dense and well-bonded integrated structure, i.e., a layered connector.

[0078] (3) Performance testing: The performance testing method is the same as in Example 1.

[0079] Figure 3 The microstructure and interface bonding of the connector assembly provided in Embodiment 3 of the present invention are shown; for example Figure 3 As shown, the interface area of ​​the stacked interconnect is defect-free and structurally continuous. The FS layer and AS layer are mechanically interlocked after high-temperature sintering to achieve a high-strength bond, which has a certain service reliability. Moreover, the overall morphology of the FS layer and AS layer is free of pores and highly dense, which meets the density requirements of the interconnect in the high-temperature segmented series tubular SOC stack.

[0080] Comparative Example 1 According to La 0.8 Sr 0.2 CrO 3-δ La(NO3)3·6H2O, Sr(NO3)2, and Cr(NO3)3·9H2O were weighed in a preset stoichiometric ratio to prepare a single homogenized linker material; wherein, the powder preparation process was the same as that of the AS layer in Example 1; Green body preparation process: The obtained powder is pressed into a circular green body with a diameter of 12.7 mm under a pressure of 200 MPa, i.e., a single homogenized green body; the above single homogenized green body is heated to 1600 ℃ at a rate of 2 ℃ / min and sintered for 4 h to obtain LSC interconnect material.

[0081] Comparative Example 2 According to La 0.7 Ca 0.3 CrO 3-δ La(NO3)3·6H2O, Ca(NO3)2·4H2O, and Cr(NO3)3·9H2O were weighed in a preset stoichiometric ratio to prepare a single homogenized linker material; wherein, the powder preparation process is the same as that of the AS layer in Example 1; Green body preparation process: The obtained powder is pressed into a circular green body with a diameter of 12.7 mm under a pressure of 200 MPa, i.e., a single homogenized green body; the above single homogenized green body is heated to 1400 ℃ at a rate of 2 ℃ / min and sintered for 4 h to obtain LCC interconnect material.

[0082] Figure 4 The microstructure of the connector assembly provided in Comparative Examples 1-2 of the present invention is shown; as follows: Figure 4 As shown, although some particles in the surface morphology of LSC after sintering at 1600 ℃ and LCC after sintering at 1400 ℃ are connected to each other by forming sintering necks, there are still a large number of pores. The particles in the cross-sectional morphology are loosely arranged, and the overall porosity is high, which cannot meet the density requirements of the interconnects in the high-temperature segmented series tubular SOC stack.

[0083] Comparative Example 3 This comparative example is based on La, which is outside the preferred scope of the present invention. 0.8 Ca 0.2 Cr 0.85 Co 0.1 Zn 0.05 O 3-δ La(NO3)3·6H2O, Ca(NO3)2·4H2O, Cr(NO3)3·9H2O, Co(NO3)2·6H2O, and Zn(NO3)2·6H2O were weighed according to a preset stoichiometric ratio to prepare a single homogenized linker material; wherein, the powder preparation process is the same as that of the AS layer in Example 1; Green body preparation process: The obtained powder is pressed into a circular green body with a diameter of 12.7 mm under a pressure of 200 MPa, i.e., a single homogenized green body; the above single homogenized green body is heated to 1400 ℃ at a rate of 2 ℃ / min and sintered for 4 h.

[0084] Figure 5 The microstructure of the connector assembly provided in Comparative Example 3 of the present invention is shown, such as... Figure 5 As shown, both the surface and cross-section morphology exhibit a highly dense microstructure with good grain size uniformity. However, the material composition shows significant inhomogeneity, with dark regions, i.e., low atomic number secondary phases, appearing in both the surface and cross-section BSE images.

[0085] The performance testing methods for Comparative Examples 1-3 are the same as those for Example 1.

[0086] The test results are shown in Table 1: Table 1 Performance Tests

[0087] As shown in Table 1 above, the test results indicate that: (1) the conductivity of the asymmetric solid oxide fuel cell / electrolyte connector assembly provided by the present invention at 800 °C in an air / hydrogen dual atmosphere environment is higher than that of the individual homogenized connectors on both sides of the stacked structure at 800 °C in an air / hydrogen dual atmosphere environment. The stacked structure connector exhibits excellent conductivity in actual service environment, which can significantly reduce ohmic losses in the current transmission process, thereby helping to improve the power output and energy conversion efficiency of the SOC stack; (2) the air-side functional layer CTE of the stacked structure connector is highly matched with the contact component - cathode, and the fuel-side functional layer is highly matched with the contact component - anode. This can effectively alleviate the internal thermal stress generated by thermal cycling during battery preparation and operation, greatly reduce the risk of interface delamination, cracking or bending, thereby significantly improving the structural integrity and long-term operational reliability of the stack; (3) the stacked structure connector has excellent sintering activity, and by utilizing the difference in shrinkage rate of the functional layers on both sides during the sintering process, the stacked structure connector can achieve high conductivity at 1400 °C. It can be sintered to a dense state at ℃ (√ indicates that the sintering density meets the requirements for use of the connector), thus it can be prepared in one step with the electrolyte layer (such as YSZ, GDC) and the electrode layer through a co-sintering process. It is suitable for preparing high-strength, high-performance multi-section series SOC stacks and has good prospects for industrial application.

[0088] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0089] For the sake of simplicity, the method embodiments are described as a series of actions. However, those skilled in the art should understand that the present invention is not limited to the described order of actions, as some steps can be performed in other orders or simultaneously according to the present invention. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and components involved are not necessarily essential to the present invention.

[0090] The foregoing has provided a detailed description of the asymmetric solid oxide fuel cell / electrolyte connector assembly, its preparation method, and the solid oxide fuel cell / electrolyte provided by this invention. Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this invention. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. An asymmetric solid oxide fuel cell / electrolyte connector assembly, characterized in that, The connector assembly comprises an air-side functional layer and a fuel-side functional layer. Both the air-side and fuel-side functional layers are composed of perovskite-type rare-earth chromates, with the chemical composition expressed as: La. 1-x A x Cr 1-y-z B y C z O 3-δ (0.2≤x≤0.4, 0≤y≤0.8, 0≤z≤0.1); where A is selected from Ca or Sr, B is selected from Co or Fe, and C is selected from Zn, Ti, or Cu; The sum of the doping amounts of B and C in the air-side functional layer is not less than the sum of the doping amounts of B and C in the fuel-side functional layer.

2. The asymmetric solid oxide fuel cell / electrolyte connector assembly according to claim 1, characterized in that, The air-side functional layer and the fuel-side functional layer are composed of La. 1-x Sr x Cr 1-y-z Fe y Ti z O 3-δ (0.2≤x≤0.4, 0≤y≤0.8, 0≤z≤0.1).

3. The asymmetric solid oxide fuel cell / electrolyte connector assembly according to claim 2, characterized in that, The Fe doping level in the air-side functional layer is higher than that in the fuel-side functional layer, and the Ti doping level in the air-side functional layer is lower than that in the fuel-side functional layer.

4. The asymmetric solid oxide fuel cell / electrolyte connector assembly according to claim 1, characterized in that, The air-side functional layer and the fuel-side functional layer are composed of La. 1-x Sr x Cr 1-y-z Co y Cu z O 3-δ (0.2≤x≤0.4, 0≤y≤0.1, 0≤z<0.05).

5. The asymmetric solid oxide fuel cell / electrolyte connector assembly according to claim 4, characterized in that, The amount of Co doping in the air-side functional layer is not less than the amount of Co doping in the fuel-side functional layer, and the amount of Cu doping in the air-side functional layer is greater than the amount of Cu doping in the fuel-side functional layer.

6. The asymmetric solid oxide fuel cell / electrolyte connector assembly according to claim 1, characterized in that, The air-side functional layer and the fuel-side functional layer are composed of La. 1-x Ca x Cr 1-y-z Co y Zn z O 3-δ (0.2≤x≤0.4, 0≤y≤0.1, 0≤z<0.05).

7. The asymmetric solid oxide fuel cell / electrolyte connector assembly according to claim 6, characterized in that, The amount of Co doping in the air-side functional layer is not less than the amount of Co doping in the fuel-side functional layer, and the amount of Zn doping in the air-side functional layer is higher than the amount of Zn doping in the fuel-side functional layer.

8. The asymmetric solid oxide fuel cell / electrolyte connector assembly according to any one of claims 1-7, characterized in that, The electrical conductivity (σ) of the air-side functional layer in an air atmosphere at 800 °C AS The electrical conductivity (σ) of the fuel-side functional layer in air at 800°C FS Satisfy: σ AS ≥ 1.1σ FS .

9. The asymmetric solid oxide fuel cell / electrolyte connector assembly according to any one of claims 1-7, characterized in that, The conductivity (σ) of the fuel-side functional layer in a hydrogen atmosphere at 800 °C FS The conductivity (σ) of the air-side functional layer in a hydrogen atmosphere at 800°C AS Satisfy: σ FS ≥ 1.1σ AS .

10. The asymmetric solid oxide fuel cell / electrolyte connector assembly according to any one of claims 1-7, characterized in that, The coefficient of thermal expansion (CTE) of the air-side functional layer AS The coefficient of thermal expansion (CTE) of the fuel-side functional layer FS Satisfying: CTE AS With CTE FS Difference ≤ 3 × 10 -6 K -1 .

11. A method for preparing an asymmetric solid oxide fuel cell / electrolyte connector assembly according to any one of claims 1-10, characterized in that, The connector assembly is obtained by the following preparation method: According to the preset stoichiometric ratio, the metal precursor salts required to form the air-side functional layer and the fuel-side functional layer are weighed out respectively, dissolved, gelled, calcined and particle size homogenized to obtain the target phase powders corresponding to each functional layer. The target phase powders corresponding to each functional layer are laid in layers using a layer-by-layer powder spreading method. After dry pressing, a green body of the laminated structure connector is obtained. The green body of the laminated structure connector is then subjected to a first high-temperature sintering to obtain the connector assembly; or The target phase powder corresponding to each functional layer is mixed with an organic carrier to form a slurry. The two slurries are screen printed layer by layer to obtain a layered structure connector green body. The layered structure connector green body is then subjected to a second high-temperature sintering to obtain the connector assembly.

12. The method for preparing the asymmetric solid oxide fuel cell / electrolyte connector assembly according to claim 11, characterized in that, The process involves weighing the metal precursor salts required to form the air-side functional layer and the fuel-side functional layer according to a preset stoichiometric ratio, dissolving them, and then performing gelation, calcination, and particle size homogenization treatments, including: The metal precursor salts required for the air-side functional layer and the metal precursor salts required for the fuel-side functional layer are dissolved to form AS mixed solution and FS mixed solution, respectively. Citric acid and ethylene glycol are then added to the two mixed solutions, and the mixture is heated and stirred until a gel-like substance is formed. After drying, a dry gel is obtained. The homogenization process is completed after the dry gel is ground, calcined, and ball-milled.

13. The method for preparing the asymmetric solid oxide fuel cell / electrolyte interconnect assembly according to claim 12, characterized in that, In the mixed solution system, the concentration ratio of citric acid, ethylene glycol and total metal ions is 1:1:

1.

14. The method for preparing the asymmetric solid oxide fuel cell / electrolyte connector assembly according to claim 12, characterized in that, The calcination temperature is 700-900 ℃, and the time is 5-10 h.

15. The method for preparing the asymmetric solid oxide fuel cell / electrolyte connector assembly according to claim 12, characterized in that, The particle size of the target phase powder is 0.05-5 μm.

16. The method for preparing the asymmetric solid oxide fuel cell / electrolyte connector assembly according to claim 11, characterized in that, The pressure of the dry press is 100-300 MPa; The first high-temperature sintering temperature is 1300-1400 ℃, and the time is 2-4 h.

17. The method for preparing the asymmetric solid oxide fuel cell / electrolyte connector assembly according to claim 11, characterized in that, The organic carrier is selected from at least one of ethanol, ethyl acetate, α-terpineol, ethyl cellulose, castor oil, polyvinylpyrrolidone, triethanolamine, polyvinyl butyral, and polyethylene glycol; The mass ratio of the target phase powder to the organic carrier is 1:1-1.3; The second high-temperature sintering temperature is 1350-1450 ℃, and the time is 4-8 h.

18. An asymmetric solid oxide fuel cell / electrolyte, characterized in that, It includes the asymmetric solid oxide fuel cell / electrolyte connector assembly described in any one of claims 1-10.

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