Metal-supported solid oxide battery nickel-iron support body, total battery and preparation method

Abstract

The invention belongs to the technical field of solid oxide batteries, and discloses a nickel-iron support body of a metal-supported solid oxide battery, a total battery and a preparation method. The nickel-iron supporting body of the metal-supported solid oxide battery is made of a nickel-iron alloy material in a reducing atmosphere, a gradient pore structure with gradient pore distribution is prepared and formed through a double-layer casting phase inversion process, and the gradient pore structure is a composite structure comprising a finger-shaped pore channel layer and a skin layer. Compared with a ceramic material, the composite material has higher mechanical strength and thermal conductivity, can better bear thermal shock and mechanical stress, is particularly suitable for high-temperature and rapid thermal cycle working environments, and can keep good structural stability under the rapid heating condition of 50 DEG C / min.

Description

Technical Field

[0001] The present invention belongs to the technical field of solid oxide batteries, and in particular relates to a nickel-iron support body of a metal-supported solid oxide battery, a full battery and a preparation method. Background Art

[0002] A solid oxide fuel cell (SOFC) is an electrochemical energy conversion device based on high-temperature redox reactions, capable of directly converting chemical energy into electrical energy. Its basic structure consists of a porous anode, a dense oxide electrolyte, and a porous cathode. With the increasing global demand for energy efficiency and low carbon emissions, SOFC technology holds broad application prospects in distributed energy systems, energy storage, and hydrogen production. As a low-emission, high-efficiency energy conversion technology, SOFC not only improves energy utilization but also provides important technical support for achieving sustainable energy development.

[0003] In the design of SOFCs, the fundamental role of the support is to provide mechanical support and ensure the stability of the cell's components. Currently, the design of the anode support is the mainstream research direction because it can provide this fundamental support function while simplifying the structural design and improving the overall performance and efficiency of the cell. The anode support not only needs to support the effective diffusion of the reactant gases but also has to possess high electronic conductivity to facilitate the smooth progress of the oxidation reaction. However, conventional anode supports typically have a low porosity and a relatively uniform pore size distribution. This results in low gas diffusion efficiency, particularly at high current densities, where concentration polarization is severe, which in turn affects cell performance. Furthermore, ceramic materials are highly brittle and cannot effectively withstand rapid temperature increases (>30°C / min) and the mechanical stresses experienced during operation, making the cell prone to cracking and limiting its reliability in practical applications. Summary of the Invention

[0004] To overcome the problems existing in the related art, the present invention discloses a nickel-iron support for a metal-supported solid oxide battery, a full battery, and a preparation method. The present invention aims to improve the battery's electrochemical performance and rapid thermal cycling performance by utilizing a nickel-iron alloy as the battery support and combining it with a tape-cast phase conversion process to enhance the mechanical strength and thermal stability of the support while optimizing the gas transmission path.

[0005] The technical solution is as follows: a metal-supported solid oxide battery nickel-iron support, which is made of nickel-iron alloy under a reducing atmosphere and is prepared through a double-layer tape-casting phase transformation process to form a gradient pore structure with a gradient pore distribution. The gradient pore structure is a composite structure comprising a finger-like pore layer and a skin layer.

[0006] The pore diameter of the finger-shaped pore layer is 5-100 μm; the thickness of the finger-shaped pore layer is 300-600 μm;

[0007] The skin layer has a thickness of 1-10 μm and serves as an electrochemical reaction active area.

[0008] The nickel-iron support has a thickness of 200-600 μm and a porosity of 50%-70%.

[0009] Another object of the present invention is to provide a method for preparing a nickel-iron support for a metal-supported solid oxide battery, wherein the method is used to prepare the nickel-iron support for the metal-supported solid oxide battery, and the method comprises the following steps:

[0010] S1, preparation of support casting slurry;

[0011] S2, graphite casting slurry preparation;

[0012] S3, tape casting;

[0013] S4, phase inversion treatment;

[0014] S5, sintering to form a metal-supported solid oxide battery nickel-iron support body with the graphite casting slurry layer removed.

[0015] In step S1, a support casting slurry is prepared, comprising: mixing NiO powder and Fe2O3 powder in a ratio of 3:7 to 7:3, and N-methylpyrrolidone NMP and polyvinylpyrrolidone PVP in a ratio of 36:1 to 20:1;

[0016] The above mixture is placed in a ball mill and ball-milled for 12-24 hours to ensure the uniformity of the slurry; 0.05-0.075% of polyvinyl butyral (PVB) accounting for the mixed fraction of NiO powder and Fe2O3 powder is added to the mixed slurry, and the mixture is placed in the ball mill again and ball-milled for 12-24 hours; the obtained mixture is placed in a degassing machine and degassed for 30-60 minutes, and then taken out to obtain a support body casting slurry.

[0017] In step S2, graphite casting slurry is prepared, including: adding N-methylpyrrolidone NMP and vinylpyrrolidone PVP in a ratio of 36:1 to 20:1 and graphite powder for mixing;

[0018] The mixture was placed in a ball mill and ball-milled for 12-24 hours to ensure the uniformity of the slurry; polyvinyl butyral (PVB) was added to the mixed slurry, and the mixture was placed in a ball mill again and ball-milled for 12-24 hours to obtain a graphite casting slurry;

[0019] In step S3, tape casting comprises: coating a graphite casting slurry on a casting belt, with the casting thickness controlled to be 50-150 μm; coating a support casting slurry on the graphite casting slurry layer, with the casting thickness controlled to be 700-1000 μm.

[0020] In step S4, a phase inversion treatment is performed, comprising: immersing the tape-cast support in deionized water to form a gradient pore structure through a phase inversion process, and removing the tape-cast support after 4-12 hours and drying it in a drying oven;

[0021] In step S5, sintering includes: removing the casting tape from the dried support body containing the casting tape, placing it in an electric furnace for calcination to remove the graphite casting slurry layer, the calcination temperature is 1000-1200° C., and the calcination time is 2-4 hours.

[0022] Another object of the present invention is to provide a full battery based on a metal-supported solid oxide battery nickel-iron support, wherein the full battery is prepared using the metal-supported solid oxide battery nickel-iron support.

[0023] Another object of the present invention is to provide a method for preparing a full battery based on a metal-supported solid oxide battery nickel-iron support, the preparation method is used to prepare a full battery based on a metal-supported solid oxide battery nickel-iron support, the preparation method comprising the following steps:

[0024] Step 1, preparation of the anode functional layer: NiO and electrolyte powders are mixed in a ratio of 6:4, ethanol:ethylene glycol is in a volume ratio of 5:1, ethyl cellulose accounts for 0.1-0.2% of the mass of the mixed NiO and electrolyte powders, and graphite accounts for 0.1-0.2% of the mass of the mixed NiO and electrolyte powders, wherein ethanol accounts for 6-10% of the mass of the mixed NiO and electrolyte powders;

[0025] The mixture is placed in a ball mill and ball-milled for 1-4 hours to obtain an anode functional layer spin coating slurry; the anode functional layer spin coating slurry is spin-coated on the upper surface of the nickel-iron support of the metal-supported solid oxide battery using a desktop spin coater as the anode functional layer, and the coated anode functional layer is sintered at 1000-1200° C. for 2-4 hours to ensure that the materials are firmly bonded;

[0026] Step 2, preparation of the electrolyte layer: mixing electrolyte powder, ethanol, ethylene glycol, and ethyl cellulose, wherein ethyl cellulose accounts for 0.1-0.2% of the mass of the electrolyte powder, the volume ratio of ethanol to ethylene glycol is 5:1, and ethanol accounts for 6-10% of the mass of the electrolyte powder;

[0027] The mixture is placed in a ball mill and ball-milled for 1-4 hours to obtain an electrolyte spin-coating slurry; the electrolyte spin-coating slurry is spin-coated on the surface of the anode functional layer using a desktop spin coater, and sintered at 1300-1400° C. for 2-5 hours to form an electrolyte layer;

[0028] Step 3, preparing a barrier layer: mixing electrolyte powder, ethanol, triethanolamine, and polyvinyl butyral (PVB); placing the mixture in a ball mill and milling for 1-4 hours to obtain a barrier layer spray solution; spraying the barrier layer spray solution onto the electrolyte surface using a spray gun, and sintering at 1200-1400°C for 2-5 hours to form a barrier layer;

[0029] Step 4, preparation of the cathode layer: LSCF, electrolyte powder, ethylene glycol, isopropyl alcohol, and glycerol are mixed; the mixture is placed in a ball mill and ball milled for 1-4 hours to obtain a cathode spray solution; the cathode spray solution is sprayed on the surface of the barrier layer through a spray gun and sintered at 950-1100°C for 2-4 hours to form a cathode layer.

[0030] In steps 1 to 4, the electrolyte powder is selected from one or more of yttria-stabilized zirconia YSZ, scandia-stabilized zirconia ScSZ, gadolinia-stabilized ceria GDC, and samarium oxide-stabilized ceria SDC.

[0031] In combination with all the above technical solutions, the beneficial effects of the present invention are as follows:

[0032] (1) The present invention solves the shortcomings of traditional anode supports in terms of gas transmission efficiency, rapid thermal cycle stability and manufacturing process. Therefore, the present invention provides a nickel-iron support with excellent performance and a method for preparing a full battery. Compared with the existing technology, it has the following beneficial effects: the use of a casting process can achieve efficient preparation of a nickel-iron alloy support, and the pore structure of the support can be precisely controlled by phase transformation to form a gradient pore structure. This structure optimizes the gas transmission path and reduces the battery concentration polarization loss by forming a composite structure of finger-like channels and skin layers in the support. In addition, the nickel-iron alloy support has higher mechanical strength and thermal conductivity than ceramic materials, can better withstand thermal shock and mechanical stress, and is particularly suitable for high temperature and rapid thermal cycle working environments, so that it can maintain good structural stability under rapid heating conditions of 50°C / min.

[0033] (2) The metal-supported solid oxide battery support and its preparation method of the present invention, with its excellent electrochemical performance and thermal stability, can significantly improve the efficiency of fuel cells and high-temperature water electrolysis hydrogen production systems, meeting the demand for high-efficiency, low-emission energy conversion equipment in industrial applications. In particular, in the fields of distributed energy, hydrogen production, and energy storage, this invention will provide a market-competitive solution for the energy industry, and is expected to promote the widespread application of green energy technologies and create significant economic benefits and social value in terms of reducing production costs and improving energy utilization efficiency.

[0034] (3) The design of anode supports for solid oxide batteries still faces many technical challenges in terms of stability at high temperatures, gas transmission efficiency, and material adaptability. This invention, through the innovative combination of a nickel-iron alloy support and a gradient pore structure, effectively addresses the performance degradation problem of traditional materials in high-temperature environments and improves the battery's power output under high current density conditions.

[0035] (4) The key issues faced by traditional solid oxide batteries in practical applications include poor thermomechanical stability at high temperatures, rapid material aging, and large concentration polarization losses. This invention addresses these long-standing challenges by using an innovative nickel-iron alloy support and combining it with a gradient pore structure design to significantly improve the thermal stability and electrochemical performance of the battery, especially under rapid thermal cycling and high current density. This solution breaks through the limitations of traditional materials and provides a new technical path for the development of efficient and stable SOFC systems.

[0036] (5) Many researchers believe that the difference in thermal expansion of metal supports at high temperatures is an unavoidable technical problem, making it difficult to achieve a good thermal match with the electrolyte material. In addition, traditional metal support materials often have difficulty ensuring sufficient pore structure to support gas diffusion and electrochemical reactions while meeting the requirements of high strength and conductivity. The present invention breaks this technical prejudice by introducing nickel-iron alloy and innovating the phase conversion casting process, successfully achieving the thermal expansion matching of the material and the optimization of the pore structure, ensuring that the battery can still operate stably in a high-temperature environment, improving the overall performance, and overcoming the limitations of industry technology development. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present disclosure and, together with the description, serve to explain the principles of the present disclosure;

[0038] Figure 1 This is a flow chart of a method for preparing a nickel-iron support for a metal-supported solid oxide battery provided by an embodiment of the present invention;

[0039] Figure 2The XRD diffraction patterns of the nickel-iron support body prepared by the present invention in the sintered state and the reduced state;

[0040] Figure 3 The cross-section SEM images of the nickel-iron support and the finger-shaped hole produced by the present invention, (a) is a cross-section SEM image of the nickel-iron support, and (b) is a cross-section SEM image of the nickel-iron finger-shaped hole;

[0041] Figure 4 The load-displacement diagram of the nickel-iron support body produced by the present invention in the sintered state and the reduced state after sintering at 1350°C;

[0042] Figure 5 The pore wall micro-SEM images of the nickel-iron support body made by the present invention before and after reduction, (a) is a micro-SEM image of the pore wall skeleton of the nickel-iron support body before reduction, and (b) is a micro-SEM image of the pore wall skeleton of the nickel-iron support body after reduction;

[0043] Figure 6 These are SEM images of the microscopic cross-section and electrolyte surface of the nickel-iron supported solid oxide full battery produced in the present invention. (a) is a microscopic cross-section SEM image of the anode, electrolyte and cathode of the full battery, and (b) is a surface SEM image of the sintered electrolyte.

[0044] Figure 7 The power density diagram of the nickel-iron supported solid oxide battery produced by the present invention at various temperatures;

[0045] Figure 8 These are the AC impedance spectra of the nickel-iron supported solid oxide battery produced in the present invention at various temperatures.

[0046] Figure 9 The power density diagram of each stage under rapid thermal cycling of the nickel-iron supported solid oxide battery produced by the present invention;

[0047] Figure 10 These are the AC impedance spectra of the nickel-iron supported solid oxide battery produced in this invention at various stages under rapid thermal cycling. DETAILED DESCRIPTION

[0048] To make the above-mentioned objects, features, and advantages of the present invention more readily apparent, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings. The following description sets forth numerous specific details to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art may make similar modifications without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0049] The innovation of this invention lies in the fact that the nickel-iron support proposed in this invention addresses the technical bottlenecks of traditional anode supports in terms of gas transmission efficiency, thermal cycle stability, and structural control. By combining the nickel-iron alloy material system, gradient pore structure design, and phase transformation double-layer casting process, a metal support with multi-scale through-hole channels and dense interface integration is constructed. This support not only achieves the coordinated optimization of long-range gas diffusion channels and three-phase reaction interfaces in structure, but also exhibits good electrical conductivity and thermomechanical stability at high temperatures, significantly improving the output performance and stability of the full battery under high temperature and high current density conditions.

[0050] The preparation process of this invention maintains structural continuity and compactness while exhibiting excellent controllability and reproducibility, making it suitable for low-energy sintering and mass production. This provides an effective path for the engineering of metal-supported SOFC devices. Electrochemical performance testing and rapid thermal cycling evaluation demonstrate that the prepared metal support exhibits stable and reliable performance in applications such as fuel cells and high-temperature electrolysis, demonstrating broad engineering application prospects and potential for widespread adoption.

[0051] Example 1: The present invention provides a nickel-iron support for a metal-supported solid oxide battery.

[0052] The nickel-iron support of the metal-supported solid oxide battery is prepared by a double-layer tape-casting phase conversion process and has a gradient pore distribution. The gradient pore structure includes a finger-like pore layer and a skin layer.

[0053] The finger-shaped channel layer has a larger pore size (5-100 μm) and a higher porosity. The skin layer is much thinner (1-10 μm) than the finger-shaped channel layer (300-600 μm) and has smaller pores that serve as electrochemical reaction active areas.

[0054] The thickness of the nickel-iron support of the metal-supported solid oxide battery should be 200-600 μm, and the porosity should be 50%-70%. Under a reducing atmosphere, the nickel-iron support of the metal-supported solid oxide battery is made of nickel-iron alloy (Ni-Fe).

[0055] Example 2, as Figure 1 As shown, the nickel-iron support of the metal-supported solid oxide battery is prepared according to the following method:

[0056] S1, preparation of support casting slurry;

[0057] Mix NiO powder and Fe2O3 powder in a ratio of 3:7 to 7:3, and N-methylpyrrolidone NMP and polyvinylpyrrolidone PVP in a ratio of 36:1 to 20:1;

[0058] The above mixture is placed in a ball mill and ball-milled for 12-24 hours to ensure the uniformity of the slurry; 0.05-0.075% of polyvinyl butyral (PVB) accounting for the mixed fraction of NiO powder and Fe2O3 powder is added to the mixed slurry, and the mixture is placed in the ball mill again and ball-milled for 12-24 hours; the obtained mixture is placed in a degassing machine and degassed for 30-60 minutes, and then taken out to obtain a support body casting slurry.

[0059] Exemplarily, the ratio of NiO powder to Fe2O3 powder is determined by the electrolyte material, and the mass ratio ranges from (3:7) to (7:3).

[0060] S2, graphite casting slurry preparation;

[0061] N-methylpyrrolidone NMP and vinylpyrrolidone PVP are mixed in a ratio of 36:1 to 20:1, and graphite powder is added;

[0062] The mixture was placed in a ball mill and ball-milled for 12-24 hours to ensure the uniformity of the slurry; polyvinyl butyral (PVB) was added to the mixed slurry, and the mixture was placed in a ball mill again and ball-milled for 12-24 hours to obtain a graphite casting slurry;

[0063] S3, tape casting;

[0064] Graphite casting slurry is coated on the casting belt, and the casting thickness is controlled to be 50-150 μm; support casting slurry is coated on the graphite casting slurry layer, and the casting thickness is controlled to be 700-1000 μm.

[0065] S4, phase inversion treatment;

[0066] The tape-cast support containing the tape is immersed in deionized water to form a gradient pore structure through a phase inversion process. After 4-12 hours, the tape-cast support is taken out and dried in a drying oven at a temperature of 25-45 degrees Celsius.

[0067] S5, sintering to form a metal-supported solid oxide battery nickel-iron support body with the graphite casting slurry layer removed.

[0068] The dried support containing the casting tape is removed from the casting tape, and is placed in an electric furnace for calcination to remove the graphite casting slurry layer. The calcination temperature is 1000-1200°C and the calcination time is 2-4 hours to preliminarily form a metal-supported solid oxide battery nickel-iron support with the graphite casting slurry layer removed.

[0069] Due to the high-temperature calcination process, the lower graphite layer of the nickel-iron support of the metal-supported solid oxide battery is removed, exposing the gradient pores of the nickel-iron support of the metal-supported solid oxide battery, and the lower surface of the nickel-iron support of the metal-supported solid oxide battery presents an open straight pore morphology.

[0070] Example 3, the present invention also provides a full battery based on a metal-supported solid oxide battery nickel-iron support.

[0071] The present invention also provides a method for preparing a full battery based on a metal-supported solid oxide battery nickel-iron support, which specifically comprises the following steps:

[0072] Step 1, preparation of the anode functional layer: NiO, electrolyte powder, ethanol, ethylene glycol, graphite, and ethyl cellulose are mixed in a certain ratio, the ratio of NiO: electrolyte powder is 6:4, ethyl cellulose accounts for 0.1-0.2% of the mass of the mixed powder of NiO and electrolyte, graphite accounts for 0.1-0.2% of the mass of the mixed powder of NiO and electrolyte, the volume ratio of ethanol: ethylene glycol is 5:1, and ethanol accounts for 6-10% of the mass of the mixed powder of NiO and electrolyte.

[0073] The mixture is placed in a ball mill and ball-milled for 1-4 hours to obtain an anode functional layer spin-coating slurry. The anode functional layer spin-coating slurry is spin-coated onto the upper surface of the nickel-iron support of the metal-supported solid oxide battery using a desktop spin coater as the anode functional layer. The coated anode functional layer is sintered at 1000-1200°C for 2-4 hours to ensure a strong bond between the materials.

[0074] Step 2, preparation of the electrolyte layer: electrolyte powder, ethanol, ethylene glycol, and ethyl cellulose are mixed in a certain proportion, the proportion being: ethyl cellulose accounts for 0.1-0.2% of the mass of the electrolyte powder, the volume ratio of ethanol to ethylene glycol is 5:1, and ethanol accounts for 6-10% of the mass of the electrolyte powder.

[0075] The mixture is placed in a ball mill and ball milled for 1-4 hours to obtain an electrolyte spin coating slurry. The electrolyte spin coating slurry is spin coated on the surface of the anode functional layer using a desktop spin coater and sintered at 1300-1400°C for 2-5 hours to form an electrolyte layer.

[0076] Step 3, preparation of barrier layer: electrolyte powder, ethanol, triethanolamine and polyvinyl butyral (PVB) are mixed in a certain proportion, wherein the proportion is: polyvinyl butyral (PVB) accounts for 0.04-0.1% of the mass of the electrolyte powder, triethanolamine accounts for 0.15-0.25% of the mass of the electrolyte powder, and ethanol accounts for 14-18% of the mass of the electrolyte powder.

[0077] The mixture is placed in a ball mill and ball-milled for 1-4 hours to obtain a barrier layer spray solution, which is sprayed onto the electrolyte surface using a spray gun and sintered at 1200-1400° C. for 2-5 hours to form a barrier layer.

[0078] Step 4, preparation of the cathode layer: lanthanum strontium cobalt iron powder (LSCF), electrolyte powder, ethylene glycol, isopropyl alcohol, and glycerol are mixed in a certain proportion, the ratio being: LSCF: electrolyte powder = 7:3, isopropyl alcohol: ethylene glycol: glycerol volume ratio = 12.5:2.5:1, and isopropyl alcohol accounts for 10-15% of the mass ratio of LSCF and electrolyte mixed powder.

[0079] The mixture is placed in a ball mill and ball-milled for 1-4 hours to obtain a cathode spray solution. The cathode spray solution is sprayed on the surface of the barrier layer through a spray gun and sintered at 950-1100° C. for 2-4 hours to form a cathode layer.

[0080] Exemplarily, in steps 1 to 4, the electrolyte powder is selected from one or more of yttria-stabilized zirconia (YSZ), scandia-stabilized zirconia (ScSZ), gadolinia-stabilized ceria (GDC), and samarium oxide-stabilized ceria (SDC).

[0081] Example 4: Preparation of nickel-iron support by tape casting phase conversion method.

[0082] First, prepare the nickel-iron support casting slurry: the solute is mainly NiO powder and Fe2O3 powder, and weigh 20g of each powder (mass ratio 1:1) and add them into the ball mill.

[0083] Next, 0.6 g of PVP as a dispersant and 16 g of NMP as a solvent were weighed and added to the above ball mill jar, and the mixture was placed in a ball mill for 12 h at a speed of 400 rpm to ensure that the slurry was evenly mixed.

[0084] Then, 2.8g of PVB is added as a binding agent in the mixed slurry, and it is again placed in a ball mill and ball-milled for 24h. When the nickel-iron support casting slurry is prepared, the preparation of the sacrificial layer graphite casting slurry is carried out. 3g of graphite powder, 0.3g of PVP, and 8g of NMP are also weighed and added to a ball mill. After the ball mill is placed in a ball mill and ball-milled for 12h, 1.35g of PVB is added and ball-milled again for 24h. So far, the nickel-iron support and the graphite sacrificial layer casting slurry are obtained. Before carrying out the slurry casting, the nickel-iron support casting slurry needs to be put into a deaerator and degassed for 30min. This is to be able to remove a large amount of bubbles that the slurry contains inside during the ball milling mixing process to a certain extent, and the graphite layer can be pyrolyzed during the subsequent sintering molding process. Internal bubbles have no effect on the support morphology, so the deaeration procedure is not carried out.

[0085] After the above process is completed, the double-layer casting of the nickel-iron support is started: first, the scraper height is adjusted to 120μm to ensure the thickness of the graphite layer, then the graphite casting slurry is poured on the casting belt and cast, and immediately after the end, the support casting slurry is cast on the graphite layer, and the scraper height is adjusted to 1000μm. The above-mentioned cast support is immersed in deionized water for 4h of phase inversion treatment. At this time, the support will form an asymmetric three-layer structure from bottom to top, a skin layer formed in direct contact with deionized water, a finger-like pore layer with a larger thickness in the middle and vertically parallel gradient pores, and a sponge layer in direct contact with the casting belt, and the position of the sponge layer is replaced by graphite.

[0086] The process of preparing a finger-like pore support by the phase inversion method is essentially to trigger a phase change of the system through the dynamic exchange of solvent and non-solvent, and finally form a multi-level pore structure with a functional gradient. Example 1 PVB is used as the polymer skeleton material, NMP is used as the solvent, and deionized water is used as the non-solvent to form a ternary system. When the cast support is immersed in an aqueous gel bath, the strong mutual solubility of NMP and water triggers a rapid solvent exchange: NMP molecules diffuse from the inside of the solution into the water, while water molecules reversely penetrate into the polymer system. This bidirectional diffusion initially maintains a relative balance, and the solution still presents a uniform state, but as the NMP concentration decreases sharply, the PVB segments begin to aggregate locally, and the system gradually approaches the thermodynamic instability critical point. In this process, PVP plays a key role as a dispersant. The polar groups in its molecules inhibit the excessive aggregation of PVB segments through the steric effect, ensuring the controllability of the phase separation process.

[0087] When the NMP / water exchange rate reaches a certain level, the system becomes thermodynamically unstable, and phase separation occurs, entering the demixing stage. The boundary between the PVB-rich and depleted phases rapidly forms on the microscale. The kinetics of the phase separation process directly determine the pore structure morphology. Due to the instantaneous and massive release of NMP at the NMP / water interface, the PVB concentration suddenly increases, and PVB molecules rapidly accumulate and solidify at the gas-liquid interface, forming a dense cortex with a thickness of approximately hundreds of nanometers to several microns. Within the support, a distributed phase transition occurs due to the differential NMP / water diffusion gradient, forming a composite pore structure with coexisting finger-like and sponge-like pores. Near the surface, the rapid intrusion of deionized water triggers instantaneous phase separation, forming vertically penetrating finger-like macroporous channels. Deeper regions, due to increased diffusion resistance, undergo delayed phase separation, forming interconnected micron-scale sponge-like pores.

[0088] The support body after the phase transformation is taken out and placed in a forced air drying oven for drying at a temperature of 30°C. After drying, several support body original sheets with a diameter of 15 mm are cut out with a slicer and placed in a box-type electric furnace for sintering at a sintering temperature of 1100°C and a sintering time of 2 hours to initially form a nickel-iron support body.

[0089] After high-temperature sintering of the nickel-iron support, organic materials such as PVB and PVP decompose under the heat, leaving behind a three-dimensional pore network that, together with the metal oxide particles, forms a rigid skeleton. The dense surface structure transforms into a functional interface with dual ionic and electronic conductivity. The gradient pore system not only provides a low-resistance path for gas transport but also effectively mitigates thermal stress concentration through gradual changes in pore size.

[0090] The morphology of the nickel-iron support was observed using an Apreo S scanning electron microscope. Figure 3 Figure (a) is a cross-sectional SEM image of the nickel-iron support. Figure 5 Figure (a) is a microscopic SEM image of the pore wall skeleton of the nickel-iron support before reduction. Figure 3 The overall structural morphology of the gradient hole in Figure (a) Figure 5 The microscopic dense skeleton and strong pore wall in Figure (a) show that the support has a finger-like pore structure perpendicular to the substrate.

[0091] The smooth pore walls and optimized pore structure help reduce resistance and improve conductivity, while the dense skeleton and strong pore walls provide sufficient mechanical support to resist thermal cycling and mechanical stress, extending the service life of the support. Furthermore, during the high-temperature calcination process, the lower graphite layer decomposes due to heat, thereby removing the bottom sponge layer, exposing the gradient porosity of the nickel-iron support and presenting an open straight pore morphology on the lower surface of the support. The relatively dense skin layer increases the electrode / electrolyte contact area with smaller pores, enhancing the reactivity of the three-phase interface reaction. Figure 3 Figure (b) is the SEM image of the cross section of nickel-iron finger-shaped pores. Figure 3 The cross-section of the finger-like pores in Figure (b) has a uniform pore structure, providing sufficient gas diffusion channels while maintaining the necessary mechanical strength. The uniform pore size distribution and regular pore shape facilitate uniform diffusion of the fuel gas and reduce concentration polarization.

[0092] Figure 2 The XRD diffraction patterns of nickel-iron support in sintered and reduced states are shown in Figure 2. Figure 2 It can be seen that before reduction, the nickel-iron support is mainly in the form of oxides, mainly including NiO and NiFe2O4, among which NiFe2O4 is a typical spinel structure formed by the solid-phase reaction between the original nickel-iron oxide NiO and Fe2O3 during the high-temperature sintering process, providing good structural stability and electrochemical performance at high temperatures.

[0093] The battery was placed in a tubular atmosphere furnace and reduced with pure H₂ gas at 700°C for 2 hours to obtain a reduced support. During the reduction process, the NiO and NiFe₂O₄ in the nickel-iron support were gradually reduced to a Ni-Fe alloy structure by the H₂. Comparing the XRD patterns before and after reduction clearly shows the disappearance of the NiO and NiFe₂O₄ diffraction peaks, while the characteristic peaks of the Ni-Fe alloy appear, indicating that the NiO and NiFe₂O₄ completely transformed into the metallic phase during the reduction process.

[0094] In order to obtain the fracture strength of the support body before and after reduction, the experiment used a coaxial ring force method and a universal material testing machine to test the strength. Figure 4 The load displacement diagram of the battery before and after reduction. Fracture strength is the ability of a material to withstand external stress or thermal stress without breaking or cracking. Figure 4 It can be seen that the fracture strength of the support body in the oxidized state is 43.95MPa, but the displacement is small, only 187μm, which indicates that the material exhibits good rigidity and low plastic deformation when subjected to external stress. At this time, the support body is mainly composed of NiO and NiFe2O4. The dense skeleton and strong pore wall can provide strong mechanical support. After reduction, the fracture strength of the support body dropped to 38.35MPa, while the displacement increased significantly to 323μm, indicating that the plastic deformation ability of the material under external force increased and the rigidity decreased. This reduction in rigidity is because during the reduction process, the NiO and NiFe2O4 in the support body are reduced to form a Ni-Fe alloy structure. Although this leads to an increase in grain strength and an increase in alloy strength, it also causes an increase in porosity and changes in the internal structure of the material.

[0095] Figure 5 Figure (b) is a microscopic SEM image of the pore wall skeleton after the nickel-iron support body is reduced. Figure 5 Figure (a) and Figure 5 From the comparison in Figure (b), it can be seen that the original pore structure of the support has been changed, and more nanopores have been formed during the reduction process, which reduces the stiffness of the material when subjected to stress, resulting in a decrease in strength. Although the overall strength of the support has decreased, the reduced Ni-Fe alloy has improved the plasticity and ductility of the material, allowing the support to maintain good structural stability under larger displacements. Moreover, although the fracture strength of the reduced nickel-iron support has decreased when facing rapid thermal cycles, the improvement in its plasticity and ductility compensates for this disadvantage, enabling the material to effectively cope with thermal expansion and thermal stress, and helping to avoid cracks and structural failure during thermal cycling.

[0096] In general, the strength change of the nickel-iron support after reduction is a balance between strength and plasticity, and the ductility and thermal stability of the nickel-iron support are enhanced to a certain extent.

[0097] Example 5: Preparation of a full nickel-iron supported solid oxide battery.

[0098] First, prepare the anode functional layer: 1.2g of NiO powder and 0.8g of YSZ powder, respectively, in a mass ratio of 6:4, are weighed and added to a ball mill. Then, 0.2g of ethyl cellulose as a binder, 0.2g of graphite as a pore-forming agent, 20ml of ethanol, and 4ml of ethylene glycol as solvents and dispersants are added to the same ball mill. The mixture is then ball-milled for 3 hours at 400 rpm to ensure uniform mixing. A nickel-iron support is attached to the stage of a tabletop spin coater using a vacuum pump. The milled anode functional layer slurry is then drop-coated onto the support surface. The spin coater is set to 6000 rpm and started. Spin coating is repeated three times for 30 seconds, ensuring a total weight of approximately 0.1g. After air drying, the coated battery is sintered at 1050°C for 2 hours to ensure a secure bond.

[0099] Secondly, prepare the electrolyte layer: the electrolyte is also prepared by spin coating. Weigh 2g of YSZ powder, 0.2g of ethyl cellulose, 20ml of ethanol and 4ml of ethylene glycol and add them to a ball mill jar and mix them. Place them in a ball mill and mill for 3h. The ball mill speed is 400rpm to ensure that the slurry is evenly mixed. The spin coating process is the same as the above-mentioned anode functional layer spin coating operation, but the glue machine spins at a speed of 3000rpm for 15s and then increases the speed to 6000rpm for 20s. Repeat twice to ensure that the weight of the spin-coated slurry is about 0.1g. After air drying, the coated battery is sintered at 1350℃ for 3h, with a heating rate of 4℃ / min from 0-1000℃ and 2℃ / min above 1000℃.

[0100] Figure 6 Figure (b) shows a surface SEM image of the sintered electrolyte. The image shows a tight connection between the grains, with no obvious closed or open pores. This indicates that sufficient grain rearrangement and sintering neck growth occurred within the material during the sintering process, ultimately forming a highly densified structure. This structure effectively prevents gas leakage, improves the battery's open circuit voltage (OCV), and ensures the integrity of the unidirectional migration path of oxygen ions, helping to achieve a lower electrolyte ohmic impedance and improve electrochemical efficiency.

[0101] After sintering, spray the barrier layer: Weigh 1.25g of GDC powder, 20g of ethanol, 0.1g of PVB, and 0.4g of triethanolamine in a ball mill and mill for 3 hours to obtain a barrier layer spray solution. Place the half-cell on a heating plate at 150°C and spray the solution onto the electrolyte surface using a spray gun. Repeat the spraying process six times after the cell surface dries, ensuring a spray weight of approximately 0.03g. Sinter the sprayed cell at 1300°C for 2 hours to form the barrier layer.

[0102] Finally, prepare the cathode layer: Weigh 0.7g of LSCF, 0.3g of GDC powder, 2ml of ethylene glycol, 10ml of isopropyl alcohol, and 0.8ml of glycerol into a ball mill, mix, and mill for 3 hours to obtain the cathode spray solution. The spraying process is the same as for the barrier layer, but repeat eight times to ensure a spray weight of approximately 0.1g. The sprayed cell is sintered at 950°C for 2 hours to form the cathode layer.

[0103] At this point, the nickel-iron supported solid oxide battery is fully prepared, Figure 6 Figure (a) is a microscopic cross-sectional SEM image of the anode, electrolyte and cathode of the full battery. Figure 6 As can be seen in Figure (a), the contact surfaces of the various layers of the full battery are relatively flat and tightly bonded, which can effectively reduce the interface contact resistance. Among them, the thickness of the anode layer is about 20μm and presents an obvious porous structure, which can provide a large number of reaction areas during the reaction while ensuring gas diffusion. The electrolyte layer presents a dense structure between the anode and the cathode, which can effectively prevent gas leakage and ensure ion transmission. In addition, there are no obvious cracks or defects in the electrolyte layer, which indicates that the temperature during the sintering process is properly controlled, the internal stress of the material is effectively released, and the overall structural stability of the electrolyte layer is enhanced.

[0104] Figure 7 The polarization curve test results of nickel-iron supported solid oxide battery at different temperatures are shown. At the test temperatures of 700℃, 750℃ and 800℃, the maximum power density of the battery is 0.777W·cm -2 , 0.951W·cm -2 and 1.054 W·cm -2. From these data, it can be seen that as the temperature increases, the power density of the battery gradually increases, which shows that temperature has a significant effect on battery performance, and high temperature helps to improve the output power of the battery. This is because as the temperature increases, the migration rate of oxygen ions in the electrolyte material YSZ increases, resulting in an increase in the current density of the battery. Therefore, the increase in power density brought about by the increase in temperature is a direct manifestation of the accelerated battery reaction rate. In addition, at test temperatures of 700°C, 750°C and 800°C, the open circuit voltage (OCV) of the battery was 0.954V, 0.951V, and 0.938V, respectively. As the temperature increases, the open circuit voltage shows a gradual downward trend. Although the voltage decreases slightly, the increase in current density compensates for the decrease in voltage, thereby improving the power density.

[0105] Figure 8 The electrochemical impedance spectroscopy test results of the battery show that the ohmic impedance of the battery is 0.118Ω·cm at test temperatures of 700℃, 750℃, and 800℃, respectively. 2 , 0.105Ω·cm 2 and 0.098Ω·cm 2 As the temperature increases, the ohmic resistance gradually decreases. This is because oxygen ions can be more easily transported through YSZ, and the electronic conductivity of the electrode material at high temperature is also improved, making the transmission of electrons smoother, thereby reducing the internal impedance of the battery. In addition, as the temperature increases, the battery polarization resistance also shows a gradual downward trend. The polarization impedance of the battery is 0.285Ω·cm 2 , 0.243Ω·cm 2 , 0.226Ω·cm 2 This is because at high temperatures, the electrode material has stronger catalytic activity and can interact with the reactants more effectively, promoting their adsorption, dissociation, and recombination processes, thereby reducing the electrochemical resistance (i.e., polarization resistance) during the electrode reaction.

[0106] Figure 9 、 Figure 10 This is a graph showing the rapid thermal cycling performance test results of a nickel-iron-supported battery. The battery was subjected to five deep thermal cycles in a hydrogen fuel atmosphere at a heating rate of 50°C / min. Each thermal cycle temperature ranged from 300-750°C, with electrochemical testing performed at 750°C each time. The nickel-iron-supported solid oxide battery exhibited good stability to accommodate the rapid heating rate, with the ohmic impedance decreasing from only 0.201Ω·cm to 0.5Ω·cm after five thermal cycles. 2 Increased to 0.211Ω·cm 2 , indicating that the ionic conductivity of the electrolyte remains stable during thermal cycling. In addition, the electrolyte structure does not suffer obvious damage. The maximum power density of the battery after five thermal cycles is 0.645W·cm -2, 0.636W·cm -2 , 0.600W·cm -2 , 0.577W·cm -2 , 0.544W·cm -2 After multiple rapid temperature increases and decreases, the maximum power density of the battery gradually decreases. This decrease in power output reflects a decline in the electrode reaction activity and interface conduction efficiency under continuous thermal stress. However, it still maintains a high level, and the temperature increase is at a rate of 50°C / min, indicating that the support structure has good thermal cycling tolerance.

[0107] In the above embodiments, the description of each embodiment has its own focus. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant description of other embodiments.

[0108] The above description is only a preferred specific implementation method of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with this technical field within the technical scope disclosed by the present invention and within the spirit and principles of the present invention should be covered by the scope of protection of the present invention.

Claims

1. A nickel-iron support for a metal-supported solid oxide battery, characterized in that: The nickel-iron support is made of nickel-iron alloy under a reducing atmosphere and is prepared through a double-layer tape-casting phase conversion process to form a gradient pore structure with a gradient pore distribution. The gradient pore structure is a composite structure including a finger-like pore layer and a skin layer.

2. The nickel-iron support for metal-supported solid oxide batteries according to claim 1, characterized in that: The pore diameter of the finger-shaped pore layer is 5-100 μm; the thickness of the finger-shaped pore layer is 300-600 μm; The skin layer has a thickness of 1-10 μm and serves as an electrochemical reaction active area.

3. The nickel-iron support for metal-supported solid oxide batteries according to claim 1, characterized in that: The nickel-iron support has a thickness of 200-600 μm and a porosity of 50%-70%.

4. A method for preparing a nickel-iron support for a metal-supported solid oxide battery, characterized in that: The preparation method is used to prepare the nickel-iron support of the metal-supported solid oxide battery according to any one of claims 1 to 3, and the preparation method comprises the following steps: S1, preparation of support casting slurry; S2, graphite casting slurry preparation; S3, tape casting; S4, phase inversion treatment; S5, sintering to form a metal-supported solid oxide battery nickel-iron support body with the graphite casting slurry layer removed.

5. The method for preparing a nickel-iron support for a metal-supported solid oxide battery according to claim 4, wherein: In step S1, a support casting slurry is prepared, comprising: mixing NiO powder and Fe2O3 powder in a ratio of 3:7 to 7:3, and N-methylpyrrolidone NMP and polyvinylpyrrolidone PVP in a ratio of 36:1 to 20:1; The above mixture is placed in a ball mill and ball-milled for 12-24 hours to ensure the uniformity of the slurry; 0.05-0.075% of polyvinyl butyral (PVB) accounting for the mixed fraction of NiO powder and Fe2O3 powder is added to the mixed slurry, and the mixture is placed in the ball mill again and ball-milled for 12-24 hours; the obtained mixture is placed in a degassing machine and degassed for 30-60 minutes, and then taken out to obtain a support body casting slurry.

6. The method for preparing a nickel-iron support for a metal-supported solid oxide battery according to claim 4, wherein: In step S2, graphite casting slurry is prepared, including: adding N-methylpyrrolidone NMP and vinylpyrrolidone PVP in a ratio of 36:1 to 20:1 and graphite powder for mixing; The mixture was placed in a ball mill and ball-milled for 12-24 hours to ensure the uniformity of the slurry; polyvinyl butyral (PVB) was added to the mixed slurry, and the mixture was placed in a ball mill again and ball-milled for 12-24 hours to obtain a graphite casting slurry; In step S3, tape casting comprises: coating a graphite casting slurry on a casting belt, with the casting thickness controlled to be 50-150 μm; coating a support casting slurry on the graphite casting slurry layer, with the casting thickness controlled to be 700-1000 μm.

7. The method for preparing a nickel-iron support for a metal-supported solid oxide battery according to claim 6, wherein: In step S4, a phase inversion treatment is performed, comprising: immersing the tape-cast support in deionized water to form a gradient pore structure through a phase inversion process, and removing the tape-cast support after 4-12 hours and drying it in a drying oven; In step S5, sintering includes: removing the casting tape from the dried support body containing the casting tape, placing it in an electric furnace for calcination to remove the graphite casting slurry layer, the calcination temperature is 1000-1200° C., and the calcination time is 2-4 hours.

8. A full battery based on a metal-supported solid oxide battery nickel-iron support, characterized in that: The full battery is prepared using any one of claims 1-3 based on the nickel-iron support of a metal-supported solid oxide battery.

9. A method for preparing a full battery based on a metal-supported solid oxide battery nickel-iron support, characterized in that: The preparation method is used to prepare the full battery based on the nickel-iron support of the metal-supported solid oxide battery according to claim 8, and the preparation method comprises the following steps: Step 1, preparation of the anode functional layer: NiO and electrolyte powders are mixed in a ratio of 6:4, ethanol:ethylene glycol is in a volume ratio of 5:1, ethyl cellulose accounts for 0.1-0.2% of the mass of the mixed NiO and electrolyte powders, and graphite accounts for 0.1-0.2% of the mass of the mixed NiO and electrolyte powders, wherein ethanol accounts for 6-10% of the mass of the mixed NiO and electrolyte powders; The mixture is placed in a ball mill and ball-milled for 1-4 hours to obtain an anode functional layer spin coating slurry; the anode functional layer spin coating slurry is spin-coated on the upper surface of the nickel-iron support of the metal-supported solid oxide battery using a desktop spin coater as the anode functional layer, and the coated anode functional layer is sintered at 1000-1200° C. for 2-4 hours to ensure that the materials are firmly bonded; Step 2, preparation of the electrolyte layer: mixing electrolyte powder, ethanol, ethylene glycol, and ethyl cellulose, wherein ethyl cellulose accounts for 0.1-0.2% of the mass of the electrolyte powder, the volume ratio of ethanol to ethylene glycol is 5:1, and ethanol accounts for 6-10% of the mass of the electrolyte powder; The mixture is placed in a ball mill and ball-milled for 1-4 hours to obtain an electrolyte spin-coating slurry; the electrolyte spin-coating slurry is spin-coated on the surface of the anode functional layer using a desktop spin coater, and sintered at 1300-1400° C. for 2-5 hours to form an electrolyte layer; Step 3, preparing a barrier layer: mixing electrolyte powder, ethanol, triethanolamine, and polyvinyl butyral (PVB); placing the mixture in a ball mill and milling for 1-4 hours to obtain a barrier layer spray solution; spraying the barrier layer spray solution onto the electrolyte surface using a spray gun, and sintering at 1200-1400°C for 2-5 hours to form a barrier layer; Step 4, preparation of the cathode layer: LSCF, electrolyte powder, ethylene glycol, isopropyl alcohol, and glycerol are mixed; the mixture is placed in a ball mill and ball milled for 1-4 hours to obtain a cathode spray solution; the cathode spray solution is sprayed on the surface of the barrier layer through a spray gun and sintered at 950-1100°C for 2-4 hours to form a cathode layer.

10. The full battery based on the nickel-iron support of the metal-supported solid oxide battery according to claim 9, characterized in that: In steps 1 to 4, the electrolyte powder is selected from one or more of yttria-stabilized zirconia YSZ, scandia-stabilized zirconia ScSZ, gadolinia-stabilized ceria GDC, and samarium oxide-stabilized ceria SDC.

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