Electrolyte coating compatible with metal-supported anode and preparation method thereof

Abstract

The invention discloses an electrolyte coating compatible with a metal-supported anode and a preparation method of the electrolyte coating, and belongs to the technical field of solid oxide fuel cells. The electrolyte coating comprises a dopant and a matrix; wherein the matrix comprises at least one of YSZ and GDC; the doping agent comprises a composition of a nano oxide and at least one of Al2O3, Sc2O3, MgO, NiO, Co3O4 and Y2O3, the doping amount of the doping agent is 0.5 wt%-3.5 wt%, and the doping amount of the nano oxide is 0.35 wt%-0.45 wt%; and the difference between the thermal expansion coefficient of the electrolyte coating and the thermal expansion coefficient of the metal support anode is less than or equal to 3.5%. The thermal expansion coefficients of the electrolyte coating and the metal support anode are matched, the interface bonding quality can be remarkably improved, and the risk of thermal mismatch in the high-temperature operation and thermal cycle process is reduced.

Description

Technical Field

[0001] This application belongs to the field of solid oxide fuel cell technology, specifically relating to an electrolyte coating compatible with a metal-supported anode and its preparation method. Background Technology

[0002] SOFCs, as efficient and environmentally friendly energy conversion devices, have broad application prospects in distributed power generation, industrial waste heat utilization, and portable power supplies. Among their core components—anode, electrolyte, and cathode—metal-supported anodes (such as Ni-based or Fe-based alloys) have become a key structure for improving the engineering applicability of devices due to their combination of mechanical strength advantages and cost-effectiveness.

[0003] However, the coefficient of thermal expansion (CTE) of metal-supported anodes differs significantly from that of traditional electrolytes (such as those doped with zirconium oxide or cerium oxide), resulting in severe thermal stress during high-temperature operation and thermal cycling at 500℃~900℃. This thermal stress can lead to interface delamination, electrolyte coating cracking, and rapid battery performance degradation, severely limiting the long-term stability and commercial application of SOFCs. Specifically, the coefficient of thermal expansion of metal-supported anodes (11.5×10⁻⁶) differs significantly from that of traditional electrolytes (such as those doped with zirconium oxide or cerium oxide), resulting in severe thermal stress. -6 K -1 ~12.5×10 -6 K -1 ) and electrolytes (9×10 -6 K -1 ~11×10 -6 K -1 The CTE difference is usually more than 5%, and the resulting thermal stress exceeds the fracture strength threshold (≥60MPa) of the electrolyte material, causing microstructural failure.

[0004] Therefore, there is an urgent need for an electrolyte coating that can match the coefficient of thermal expansion of the metal-supported anode in order to optimize the interfacial bonding quality between the electrolyte and the anode. Summary of the Invention

[0005] The purpose of this application is to provide an electrolyte coating compatible with metal-supported anodes and its preparation method, which can solve the thermal mismatch problem caused by the difference in thermal expansion coefficients between metal-supported anodes and electrolytes in SOFCs.

[0006] To achieve the above objectives, this application provides an electrolyte coating compatible with a metal-supported anode, comprising a dopant and a substrate; wherein, The matrix includes at least one of YSZ and GDC; The dopant includes a composition of nano-oxide and at least one of Al2O3, Sc2O3, MgO, NiO, Co3O4 and Y2O3, with the doping amount of the dopant being 0.5wt%~3.5wt% and the doping amount of the nano-oxide being 0.35wt%~0.45wt%. The difference between the coefficient of thermal expansion of the electrolyte coating and the coefficient of thermal expansion of the metal-supported anode is ≤3.5%.

[0007] Among them, YSZ is 8 mol% Y2O3-doped zirconium oxide, and GDC is 20 mol% Gd2O3-doped cerium oxide.

[0008] Furthermore, the coefficient of thermal expansion of the electrolyte coating is 11.0 × 10⁻⁶. -6 K -1 ~11.8×10 -6 K -1 The thickness of the electrolyte coating is 15μm~25μm.

[0009] Furthermore, the electrolyte coating comprises 1.25 wt% Al2O3, 0.45 wt% Sc2O3, 0.35 wt% nano ZrO2, and the balance YSZ.

[0010] Furthermore, the electrolyte coating comprises 0.65 wt% Y2O3, 1.25 wt% MgO, 0.45 wt% nano CeO2, and the balance GDC.

[0011] Furthermore, the electrolyte coating comprises 1.3 wt% NiO, 0.25 wt% nano ZrO2, and a composite matrix comprising YSZ and GDC in a mass ratio of 2.3:1.

[0012] Furthermore, the metal support anode is a Ni-Cr alloy or an Fe-Cr alloy, with the Ni-Cr alloy containing 10wt% Cr and the Fe-Cr alloy containing 20wt% Cr.

[0013] Secondly, this application also provides a method for preparing an electrolyte coating compatible with a metal-supported anode, comprising the following steps: Prepare raw material powders for dopants and matrix; The raw material powder is deposited on the surface of the metal support anode by atmospheric plasma spraying or sol-gel method.

[0014] Furthermore, it also includes plasma etching and chemical roughening treatment of the metal support anode before deposition or spraying, so that the surface roughness of the metal support anode is 0.77μm~0.93μm and the contact angle is <25°. The plasma etching process involved a power of 160W and a time of 6-8 minutes; the chemical roughening process used a 0.1-0.3M nitric acid solution for 12-20 minutes and an ultrasonic frequency of 40kHz.

[0015] Furthermore, the atmospheric plasma spraying has a plasma power of 26kW~27kW, an argon to hydrogen flow ratio of 43:4.5, a spraying distance of 88.5mm~89.5mm, a powder feed rate of 35g / min, and a coating thickness of 22.3μm~23.7μm after atmospheric plasma spraying.

[0016] Furthermore, the precursor concentration of the sol-gel method is 0.8M~0.9M, the sintering temperature is 1100℃~1150℃, and the holding time is 3.5h~4.5h; the coating thickness obtained by the sol-gel method is 18.5μm~19.5μm.

[0017] In summary, this application has the following advantages: The electrolyte coating of this application is compatible with the metal-supported anode, and the difference in thermal expansion coefficient between the two is ≤3.5%, which can effectively reduce thermal stress concentration. The interfacial adhesion between the electrolyte coating and the metal-supported anode is strong, which can reduce the risk of interfacial delamination or crack propagation during operation. Through the synergistic effect of thermal expansion coefficient matching and interface optimization, the probability of structural failure of SOFC during thermal cycling and long-term high-temperature (500℃~900℃) operation can be significantly reduced, thereby significantly improving the durability and reliability of the battery. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the interface bonding between the electrolyte coating and the Ni-based metal-supported anode in Example 1.

[0019] Figure 2 The graphs show the matching curves of the coefficient of thermal expansion of the electrolyte coating in Example 1 and the conventional YSZ electrolyte coating with the Ni-based metal-supported anode.

[0020] Figure 3 The graph shows a comparison of the interfacial bonding strength test results between the electrolyte coating of Example 1 and the conventional YSZ electrolyte coating and the Ni-based metal-supported anode.

[0021] Figure 4 The figures show a comparison of the thermal stress distribution after bonding the electrolyte coating of Example 1 and the conventional YSZ electrolyte coating to a Ni-based metal-supported anode. Figure 4 (a) is a thermal stress distribution diagram of the electrolyte coating and Ni-based metal supported anode in Example 1. Figure 4 (b) is a thermal stress distribution diagram after the traditional YSZ electrolyte coating is combined with the Ni-based metal support anode.

[0022] Figure 5 The graph shows a comparison of the thermal cycling test results of the fuel cell stacks using the electrolyte coating of Example 1 and the conventional YSZ electrolyte coating, respectively.

[0023] Figure 6 The graph shows a comparison of the electrical performance test results of the fuel cell stacks using the electrolyte coating of Example 1 and the conventional YSZ electrolyte coating, respectively. Detailed Implementation

[0024] The principles and features of this application are described below with reference to embodiments. The examples are for illustrative purposes only and are not intended to limit the scope of this application. Unless otherwise specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0025] Existing technologies address the thermal mismatch problem caused by the difference in the coefficient of thermal expansion (CTE) between the metal-supported anode and the electrolyte, and mainly adopt the following solutions: (1) Adjustment of electrolyte material composition: The CTE of the electrolyte can be adjusted by doping with elements such as yttrium (Y) and scandium (Sc) or by introducing composite materials to make it close to that of the metal anode. However, this method has significant drawbacks. For example, the optimization of the doping ratio requires a trade-off between ionic conductivity (e.g., the conductivity of YSZ at 800℃ needs to be ≥0.02S / cm) and mechanical strength (hardness ≥10GPa), and a single material system is difficult to match the complex thermal expansion behavior of the metal anode. (2) Introduction of intermediate transition layer: A porous ceramic or metal-ceramic composite buffer layer is added between the anode and the electrolyte to reduce thermal stress concentration. However, this approach will significantly increase the complexity of the preparation process and manufacturing cost, and may introduce additional interfacial resistance, thereby reducing battery efficiency; (3) Optimization of preparation process: Plasma spraying, sol-gel method and other technologies are used to improve the density and adhesion of electrolyte coating. However, the existing process is difficult to achieve the dual requirements of CTE matching and interface bonding strength optimization at the same time.

[0026] Based on this, in a first aspect, this application provides an electrolyte coating compatible with a metal-supported anode, comprising a dopant and a substrate; wherein the substrate comprises at least one of YSZ (8 mol% yttrium oxide-doped zirconium oxide) and GDC (20 mol% gadolinium oxide-doped cerium oxide), and the dopant comprises a composition of nano-oxide and at least one of aluminum oxide (Al2O3), scandium oxide (Sc2O3), magnesium oxide (MgO), nickel oxide (NiO), cobalt oxide (Co3O4), and yttrium oxide (Y2O3), the doping amount of the dopant is 0.5 wt% to 3.5 wt%, and the doping amount of the nano-oxide is 0.35 wt% to 0.45 wt%; the difference between the coefficient of thermal expansion of the electrolyte coating and the coefficient of thermal expansion of the metal-supported anode is ≤3.5%.

[0027] This application achieves precise control of the CTE difference between the electrolyte coating and the metal-supported anode within 5% through the fine-tuning of multi-component doping and composite material systems, significantly reducing thermal stress during high-temperature operation and thermal cycling. Compared to existing technologies where simply adjusting the electrolyte composition (e.g., doping with Y or Sc) fails to fully match the complex thermal expansion behavior, this application achieves precise CTE control through multi-component doping design, fundamentally reducing thermal stress during high-temperature operation and thermal cycling, avoiding problems such as interface delamination and electrolyte cracking, and improving battery structural stability. The introduced nano-oxides improve the interfacial compatibility between the coating and the metal anode. This application enhances the mechanical bonding and chemical compatibility between the coating and the anode through nanoscale dopants, reducing the risk of interface delamination while avoiding the introduction of additional resistance, thus ensuring battery efficiency.

[0028] In this application, YSZ is 8 mol% Y₂O₃-doped zirconium oxide with a CTE coefficient of 10.5 × 10⁻⁶. -6 K -1 GDC is 20 mol% gadolinium oxide (Gd₂O₃) doped cerium oxide with a CTE coefficient of 12.0 × 10⁻⁶. -6 K -1 The nano-oxides include nano-zirconia (ZrO2) or nano-cerium oxide (CeO2), abbreviated as nano-ZrO2 and nano-CeO2, with a particle size of 5nm~7nm. This application introduces nano-scale oxides into the electrolyte, enhancing the mechanical toughness and thermal stability of the coating through the interfacial effect of nanoparticles. The nano-reinforcing phase can suppress excessively rapid grain growth at high temperatures, controlling the grain size to 0.3μm~1.3μm, resulting in a coating porosity of less than 1.2%, significantly improving the long-term stability of the electrolyte coating and its application in SOFC stacks.

[0029] In some optional embodiments of this application, the metal support anode is a Ni-Cr alloy or an Fe-Cr alloy, wherein the Cr content in the Ni-Cr alloy is 10wt% and the Cr content in the Fe-Cr alloy is 20wt%. Using Ni-Cr (10wt% Cr content) and Fe-Cr (20wt% Cr content) alloys as metal support anodes, through optimized design of the Cr content, achieves multiple balances in terms of thermal expansion matching, high-temperature oxidation resistance, mechanical strength, and cost control. This forms a synergistic effect with the electrolyte coating of this application, effectively solving the problems of thermal expansion coefficient mismatch and reliability of existing SOFC metal support anodes, and providing technical support for commercial applications.

[0030] In some optional embodiments of this application, the coefficient of thermal expansion of the electrolyte coating is 11.0 × 10⁻⁶. -6 K -1 ~11.8×10 -6 K -1The thickness of the electrolyte coating is 15μm~25μm.

[0031] In a preferred embodiment of this application, the electrolyte coating comprises 1.25 wt% Al₂O₃, 0.45 wt% Sc₂O₃, 0.35 wt% nano-ZrO₂, and the balance YSZ, with a coefficient of thermal expansion of 11.25 × 10⁻⁶. -6 K -1 Compared with Ni-Cr alloy (11.5×10⁻⁶), -6 K -1 The CTE coefficient of the metal-supported anode is matched. More precise CTE matching is achieved by introducing Al2O3, Sc2O3 and nano-reinforcing phases, while maintaining the high ionic conductivity of the electrolyte.

[0032] In a preferred embodiment of this application, the electrolyte coating comprises 0.65 wt% Y₂O₃, 1.25 wt% MgO, 0.45 wt% nano-CeO₂, and the balance GDC, with a coefficient of thermal expansion of 11.75 × 10⁻⁶. -6 K -1 , with Fe-Cr alloy (12.5×10 -6 K -1 The CTE coefficient of the metal-supported anode is matched.

[0033] In a preferred embodiment of this application, the electrolyte coating comprises 1.3 wt% NiO, 0.25 wt% nano-ZrO2, and a composite matrix. The composite matrix comprises YSZ and GDC in a mass ratio of 2.3:1, and has a coefficient of thermal expansion of 11.45 × 10⁻⁶. -6 K -1 The ionic conductivity is 0.035 S / cm (800℃), and the fracture toughness is 1.8 MPa·m. 1 / 2 .

[0034] Secondly, based on the same inventive concept, this application also discloses a method for preparing an electrolyte coating compatible with a metal-supported anode, comprising the following steps: S1. Prepare raw material powders for dopants and matrix with a particle size passing through a 200-mesh sieve; S2. The raw material powder is deposited on the surface of the metal support anode by atmospheric plasma spraying or sol-gel method.

[0035] This application significantly improves the interfacial adhesion between the electrolyte coating and the metal-supported anode through chemical composition adjustment, microstructure regulation, and anode surface pretreatment processes. Through multi-dimensional synergistic optimization, it also enhances the interfacial shear strength.

[0036] In step S1, the preparation of dopant and matrix raw material powders with a particle size passing through a 200-mesh sieve includes: weighing the raw material powders according to the formula, ball milling at 300 rpm to 500 rpm for 8 to 12 hours to obtain a mixed powder. The mixed powder is then vacuum dried at 75°C to 85°C for 12 to 18 hours and passed through a 200-mesh sieve. This application utilizes the high-speed shear force of mechanical ball milling to fully disperse the dopant and matrix powders, avoiding component segregation. The uniform component distribution ensures the consistency of the thermal expansion coefficient of the electrolyte coating, keeping the CTE difference between it and the metal-supported anode ≤ 3.5%, thereby reducing thermal stress during high-temperature operation.

[0037] In step S2, the metal support anode is first subjected to plasma etching and chemical roughening treatment before deposition or spraying, resulting in a surface roughness of 0.77 μm to 0.93 μm and a contact angle < 25°. The plasma etching treatment uses a power of 160 W for 6 to 8 minutes; the chemical roughening treatment uses a 0.1 M to 0.3 M nitric acid solution for 12 to 20 minutes, with an ultrasonic frequency of 40 kHz. This application achieves a micron-level rough surface by performing plasma etching and chemical roughening (acid pickling) on ​​the metal support anode surface, enhancing the mechanical interlocking ability between the metal support anode and the electrolyte coating, thus optimizing the interface. Furthermore, a high-precision coating deposition process (APS or sol-gel method) is combined to form a dense interface, further reducing interfacial resistance and suppressing performance degradation during long-term operation.

[0038] In step S2, the plasma power for atmospheric plasma spraying is 26kW~27kW, the argon to hydrogen flow ratio is 43:4.5, the spraying distance is 88.5mm~89.5mm, the powder feed rate is 35g / min, the coating thickness after atmospheric plasma spraying is 22.3μm~23.7μm, and the spraying temperature is 600℃~800℃. It can be seen that this application, through plasma spraying, can ensure that the YSZ / GDC matrix and dopant powder are fully melted but not decomposed, avoiding increased coating porosity due to insufficient melting or lattice distortion caused by overheating.

[0039] In step S2, the precursor concentration for the sol-gel method is 0.8 M to 0.9 M, the sintering temperature is 1100 °C to 1150 °C, and the holding time is 3.5 h to 4.5 h; the coating thickness obtained by the sol-gel method is 18.5 μm to 19.5 μm. It can be seen that this application utilizes the sol-gel method to achieve more uniform mixing of the liquid precursor, resulting in a highly consistent coating composition, making it more suitable for the dispersion of nanoscale dopants.

[0040] The technical solutions described above in this application will be explained in detail below with reference to specific embodiments.

[0041] Example 1 This embodiment provides an electrolyte coating compatible with a metal-supported anode, comprising: (1) Raw materials High-purity 8 mol% Y₂O₃-doped zirconium oxide, purity > 99.98%, D50 = 22 μm ~ 28 μm, supplied by Tosoh Corporation. Al₂O₃ (purity > 99.9%), Sc₂O₃ (purity > 99.95%), and nano-ZrO₂ (nano-ZrO₂, particle size 5 nm ~ 7 nm, purity > 99.95%).

[0042] Impurities (Fe, Si, etc. <0.005wt%) were detected by inductively coupled plasma mass spectrometry (ICP-MS, Thermo Fisher iCAP RQ), and particle size distribution deviation was ensured to be <3% by a laser particle size analyzer (Horiba LA-960).

[0043] (2) Raw material ratio control YSZ-Al2O3-Sc2O3-nano-ZrO2 composite powder was prepared with the following proportions: 1.25wt% Al2O3, 0.45wt% Sc2O3, and 0.35wt% nano-ZrO2, with the balance being YSZ. The powder was ball-milled using a high-energy planetary ball mill (Retsch PM 400, 360 rpm, ball-to-powder ratio 15:1, grinding for 10 hours, ZrO2 ball media). After mixing, the powder was vacuum-dried (80℃, 15 hours) and passed through a 200-mesh sieve.

[0044] The CTE of the composite powder was adjusted to 11.25 × 10⁻⁶. -6 K -1 Matching Ni-based anodes (CTE is 11.5 × 10⁻⁶) -6 K -1 The difference is ≤3.5%. Figure 2 Matching curves of the CTE of the electrolyte coating and the metal-supported anode are shown, illustrating the trend of CTE variation with temperature (25℃~1000℃) for different electrolyte coating formulations and metal-supported anodes. Among them, the conventional electrolyte layer (YSZ, CTE 10.5×10⁻⁶) -6 K -1 In all conventional designs of this application, YSZ is used as the electrolyte, which results in a large deviation (difference as high as 8.7%) from the metal-supported anode. In this embodiment, the CTE deviation of the YSZ system with the Ni-based anode is ≤3.5% over the entire temperature range. The matching effect is particularly significant in the SOFC operating temperature range (600℃~800℃) (difference of 2.89%~3.1%), proving that the electrolyte coating of this application effectively reduces thermal stress.

[0045] (3) Quality control A high-temperature dilatometer (Linseis L75 Platinum, accuracy ±0.03×10⁻⁶) was used. -6 K -1 The CTE (Crystal Traceability) was tested (25°C~1000°C, heating rate 3°C / min, argon atmosphere), with a repeatability error of <1%. After testing, the CTE deviation of the YSZ system in this embodiment was <1% after 400 thermal cycles, and the crack rate was <0.3%.

[0046] Differential scanning calorimetry (DSC, Netzsch STA 449 F5) was used to analyze thermal stability (25°C~1300°C), confirming the absence of phase change or thermal decomposition. A high-temperature dilatometer combined with DSC was used to analyze the phase change behavior of the material during thermal cycling. Test results showed that the CTE stability of Example 1 deviated by less than 1% after 400 thermal cycles, ensuring reliable matching.

[0047] X-ray diffraction (XRD, Rigaku SmartLab, Cu Kα radiation) verified the crystal structure. YSZ is a cubic phase (space group Fm-3m), without impurities, and the grain size is 0.3μm~1.3μm.

[0048] Mechanical properties were tested using a nanoindenter (Hysitron TI 950). The YSZ system showed a hardness of 12 GPa and a 20% improvement in fracture toughness.

[0049] (4) Electrolyte coating process The surface of the metal-supported anode is pretreated: Ni-based (Ni-10wt%Cr, CTE 11.5×10⁻⁶) anode is pretreated. -6 K -1 The anode was subjected to plasma etching (160W power, Ar / N2 mixed atmosphere, 7 min), followed by ultrasonic cleaning with 0.2M HNO3 solution (15 min, 40 kHz) to form a uniformly rough surface (Ra = 0.85 ± 0.08 μm). The surface morphology was verified by atomic force microscopy (AFM, Asylum Research MFP-3D), with a roughness deviation of <1.5%. Contact angle testing (Dataphysics OCA 25) showed improved surface hydrophilicity (contact angle 25° ± 2°), which is beneficial for coating adhesion.

[0050] The coating was obtained by atmospheric plasma spraying: An Oerlikon Metco 7MB spraying system was used with optimized parameters to spray YSZ-Al2O3-Sc2O3-nano-ZrO2 composite powder onto the surface of a Ni-based metal-supported anode. The coating thickness was controlled at 23±0.7μm, with a density of 98.5% and a thickness deviation ≤1.2%. The optimized parameters included: plasma power 26.5kW, Ar / H2 flow ratio 43:4.5, spraying distance 89mm, powder feed rate 35g / min, spraying speed 600mm / s, and spraying temperature 800℃. After spraying, sintering was performed in a Nabertherm HT 16 / 18 furnace at 1100℃ for 4 hours in an atmosphere of 5% H2 / N2 with an oxygen partial pressure <10. -7 atm.

[0051] An integrated high-precision laser rangefinder (Micro-Epsilon ILD2300, accuracy ±0.2μm) and infrared thermal imager (Teledyne FLIR T860, accuracy ±0.8℃) were used to monitor coating thickness and spraying temperature (600℃~800℃) in real time. An adaptive control algorithm (PID control) was employed to optimize power (±0.3kW) and distance (±0.8mm). Scanning electron microscopy (SEM, FEI Quanta 650) revealed that the thickness of the coating-anodine interface transition zone was <1.2μm, with no pores or microcracks. Figure 1 This diagram illustrates the interfacial bonding between the electrolyte coating and the metal-supported anode. In this embodiment, the electrolyte coating and the Ni-based metal anode achieve a tight bond via CTE (Continuous Transition). The thickness of the interfacial transition zone is <1.2 μm, and the grain size in the interfacial transition zone is 0.03 μm to 0.06 μm (totaling 800 grains). The minimum grain size in the interfacial transition zone is fixed at 0.03 μm (numbering 100 grains, concentrated in the interfacial transition zone). It can be seen that the grain distribution is concentrated in the interfacial transition zone, highlighting the uniformity and coordination of the microstructure. The CTE difference is less than 3.5%, thus effectively reducing thermal stress. The interfacial shear strength (ASTM D4541) reaches 64 MPa, an 83% improvement compared to the traditional design (35 MPa). Figure 3 As shown. Raman spectroscopy (Horiba LabRAM HR Evolution) confirmed that the coating did not undergo a stress-induced phase transition.

[0052] A coating defect detection system based on convolutional neural networks (CNN, ResNet-50) was developed to identify pores / cracks (with an accuracy of 96.5%) and provide real-time feedback to optimize spraying parameters, reducing the defect rate to 0.4%. Continuous production was achieved using an automated spraying line (FanucM-710iC), with a single coating time of only 9 minutes.

[0053] (5) Performance verification 1) Thermal stress and durability testing Simulation: A thermal cycle of 500°C to 900°C was simulated using COMSOL Multiphysics 6.0 (400 cycles, heating / cooling rate 3.5°C / min). Input parameters: YSZ elastic modulus 212 GPa, Ni-based anode 168 GPa, CTE difference ≤3.5%, thermal conductivity (YSZ: 2.2 W / m·K, Ni-based anode: 15 W / m·K). The maximum thermal stress in this embodiment is 88 MPa, which is 57% lower than the traditional design (205 MPa). Figure 4 As shown, the thermal stress distribution range of this application is 50MPa~88MPa, the stress at the center point is significantly reduced and the distribution is more uniform, while the stress range of traditional design is 120MPa~205MPa, the stress at the center point is higher and shows obvious stress concentration.

[0054] Verification: The electrolyte coating underwent 400 cycles in a thermal cycling furnace (Lindberg / Blue M TF55035A) with strain measured using an ultra-high precision strain gauge (Kyowa KFRP-5-120-C1, accuracy ±0.03με). The experimental stress and simulation error were <5%. TEM analysis of the interface after 400 cycles showed that the crack width of the electrolyte coating in this application was <0.15μm, while the traditional design exhibited a crack width of 6μm~8μm. The electrolyte coating in this application only showed microcracks without significant delamination, while the traditional design showed obvious cracks and delamination. EDS (Bruker Quantax 400) confirmed that the electrolyte coating in this application showed no Ni / Fe / Cr diffusion and excellent interfacial chemical stability. Nanoindentation testing showed that the hardness of the electrolyte coating in this application remained at 11.5GPa with a decay of <5%.

[0055] 2) Electrochemical performance testing SOFC performance was tested at 800°C using an electrochemical workstation (CH Instruments CHI760E) (H2 flow rate 160 mL / min, purity 99.999%, air flow rate 400 mL / min). The electrolyte coating, compatible with the metal-supported anode provided in this embodiment, was applied to the SOFC stack. The stack used in this application employs the same structure, including a planar metal-supported design composed of multiple stacked single-cell units separated and connected by interconnects. Each single-cell unit includes a metal-supported anode, an electrolyte coating, and a cathode, forming a sandwich structure. The stack is externally equipped with a gas manifold (fuel and air passages), sealing material (ceramic fiber), and clamping device (stainless steel frame, pressure 10 MPa~20 MPa). Structural optimization ensures thermal expansion matching, with a CTE difference ≤3.5%, to reduce thermal stress. The anode material is a Ni-Cr alloy (Cr content 10 wt%) with a thickness of 200 μm, providing mechanical support and electronic conduction. Surface pretreatment enhances adhesion with the electrolyte coating. The cathode material is either strontium-doped lanthanum cobalt iron oxide (LSCF) or strontium-doped lanthanum iron oxide (LSF), with a thickness of 20 μm, providing oxygen reduction reaction activity. The LSCF was chosen based on its high electronic / ionic mixed conductivity (>100 S / cm at 800℃) and compatibility with YSZ / GDC, and was deposited via atmospheric plasma spraying or screen printing. The interconnect material is ceramic-coated stainless steel (Crofer 22 APU, 1 mm thick), with a surface-coated anti-oxidation layer (Mn-Co spinel, 10 μm thick) to prevent Cr evaporation and gas leakage. The interconnect design includes gas channels (2 mm wide) to ensure uniform distribution of fuel (H2 / CO mixture) and oxidant (air). The number of cells per cell depends on the stack power output; a typical configuration includes 10-20 cells per 1 kW stack (each cell area 50 cm²). 2 ~100cm 2 Power density 1.3W / cm³ 2 The 20kW fuel cell stack contains 100-200 units; the 100kW stack contains 500-1000 units. The unit stack uses a repeating "anode-electrolyte-cathode-interconnector" pattern, with thermal management submodules installed every 5-10 layers to optimize the temperature gradient (<50℃). The overall stack size is adjusted according to power (1kW: 200×200×100mm; 100kW: 1000×1000×500mm). Operating temperature is 600℃-900℃, fuel utilization is 70%-80%, and system efficiency is 45%-50%. Sealing uses glass-ceramic (CTE matching, thickness 0.1mm-0.2mm). These parameters were verified through finite element simulation (ANSYS software) with thermal stress <100MPa and thermal cycle life >400 cycles.

[0056] like Figure 5 As shown, a comparison of the stability of fuel cell stacks under thermal cycling conditions (400 cycles, 500℃~900℃) reveals that the power density of traditionally designed fuel cell stacks is 1.15 W / cm². 2 Attenuation to 0.95 W / cm 2 The attenuation rate is relatively high; the power density of the fuel cell stack designed in this application is 1.38 W / cm³. 2 It only decayed to 1.35 W / cm 2 The decay rate was reduced by approximately 85%, demonstrating higher stability. This indicates that this application significantly reduces microstructural damage (such as cracks and delamination) caused by thermal cycling through optimized thermal expansion coefficient matching (CTE difference <3.5%) and interfacial bonding strength (up to 64 MPa), thereby improving the long-term stability of the fuel cell stack.

[0057] like Figure 6 As shown, the voltage decay rate of the fuel cell stack using the electrolyte coating of this application was 0.25% / 1000h during long-term operation testing (8000 hours, 800°C), while the decay rate of the conventional design under the same conditions was 1.6% / 1000h. This indicates that the present application can improve durability by 6.4 times. Figure 6 Further analysis shows that the electrolyte coating application of this application reduces the stack voltage decay rate by 84% and increases the stack power density by 20%. AC impedance spectroscopy (EIS, frequency range 0.1Hz-100kHz) also verifies that the electrolyte resistance of this application is 0.09 Ω·cm. 2 Electrode polarization resistance 0.15 Ω·cm 2 This application demonstrates that by optimizing the matching of thermal expansion coefficients (CTE difference <3.5%) and interfacial bonding strength (up to 64 MPa), it significantly improves the power density of the fuel cell stack and reduces voltage decay, exhibiting the advantage of long-term stability.

[0058] Meanwhile, 3000 hours of operation testing showed that the voltage of the fuel cell stack using the electrolyte coating of this application decreased from 1.09V to 1.08V, with a decay rate of 0.35% / 1000h (calculated as: [(1.09-1.08) / 1.09]×1000 / 3≈0.35% / 1000h), while the decay rate of the traditional design is 1.2% / 1000h. This indicates that the electrolyte coating of this application can improve durability by 3.4 times.

[0059] (6) Environmental adaptability test 1) The power density was tested under different fuel conditions, and the power density fluctuation was <2.5%; the fuels included H2, H2 / CO mixture and CH4 partially oxidized gas (CO content 10%~30%).

[0060] 2) Parameters were tested under different humidity (10%~60%RH) and temperature (500℃~950℃) conditions, and the interface strength was maintained at >60MPa and the electrolyte resistance fluctuation was <5%.

[0061] 3) Real-world case: In a 10kW SOFC distributed generation system (operating temperature 800℃, fuel H2 / CO=7:3), the stack life of the electrolyte coating applied in this embodiment reached 10,000 hours, with power decay of <3%.

[0062] Using the electrolyte coating of this embodiment, the raw material cost can be reduced to 30 USD / kg, automated production reduces labor costs by 30%, the total cost is reduced by 22%, the energy consumption of a single SOFC production unit is <0.5 kWh, and the production efficiency is increased by 40%.

[0063] All CTE tests involved in this application were conducted using a high-temperature dilatometer, with a target deviation of <3.5% and a batch pass rate >99.5%; density tests were conducted using the mercury indentation method (Porosimeter Micromeritics 9500), with a target of >98.5%; interfacial strength tests were conducted using tensile testing (Instron 5982), with a target of >62MPa; electrochemical performance was performed using a sampling method (10% of batches) to ensure a power density ≥1.38W / cm³. 2 The attenuation rate is ≤0.25% / 1000h.

[0064] Example 2 This embodiment provides an electrolyte coating compatible with a metal-supported anode, comprising: (1) Raw materials High-purity 20mol% Gd2O3 doped cerium oxide, purity >99.95%, D50 = 28μm~32μm, supplier is FuelCellMaterials.

[0065] (2) Raw material ratio control A GDC-Y₂O₃-MgO-nano-CeO₂ composite powder was prepared, comprising 0.65 wt% Y₂O₃, 1.25 wt% MgO, and 0.45 wt% nano-CeO₂, with the balance being GDC. The powder was ball-milled using the method described in Example 1, yielding a CTE of 11.75 × 10⁻⁶. -6 K -1 The composite powder is suitable for Fe-based anodes (CTE is 12.5 × 10⁻⁶). -6 K -1 The difference is ≤3.5%.

[0066] (3) Quality control A high-temperature dilatometer (Linseis L75 Platinum, accuracy ±0.03×10⁻⁶) was used. -6 K -1 The CTE (Current Thermal Effect) was tested (25°C~1000°C, heating rate 3°C / min, argon atmosphere), with a repeatability error of <1%. After testing, the CTE of the GDC system in this embodiment was <1.5% after 400 thermal cycles.

[0067] Differential scanning calorimetry (DSC, Netzsch STA 449 F5) was used to analyze thermal stability (25°C~1300°C), confirming the absence of phase change or thermal decomposition.

[0068] X-ray diffraction (XRD, Rigaku SmartLab, Cu Kα radiation) verified the crystal structure. GDC has a fluorite structure (space group Fm-3m), no impurity phases, and a grain size of 0.3μm~1.3μm.

[0069] Mechanical properties were tested using a nanoindenter (Hysitron TI 950) at 10 GPa in the GDC system, resulting in a 20% improvement in fracture toughness.

[0070] (4) Electrolyte coating process Surface pretreatment of the metal-supported anode: Fe-based (Fe-20wt%Cr, CTE 12.5×10⁻⁶) anode was applied. -6 K -1 The anode was subjected to plasma etching (160W power, Ar / N2 mixed atmosphere, 7 min), followed by ultrasonic cleaning with 0.2M HNO3 solution (15 min, 40 kHz) to form a uniformly rough surface (Ra = 0.85 ± 0.08 μm). The surface morphology was verified by atomic force microscopy (AFM, Asylum Research MFP-3D), with a roughness deviation of <1.5%. Contact angle testing (Dataphysics OCA 25) showed improved surface hydrophilicity (contact angle 25° ± 2°), which is beneficial for coating adhesion.

[0071] The sol-gel method was used to obtain the coating: a precursor solution containing Zr, Y, Mg, Gd, and Ce (concentration 0.85 mol / L, pH=3.1) was prepared according to the specified ratio, and 0.7 wt% polyvinylpyrrolidone (PVP) and 0.1 wt% polyethylene glycol (PEG) were added as dispersants and binders. Spin coating was performed at 3400 rpm for 40 s (Chemat Technology kW-4A spin coater), controlling the single-layer thickness at 2.1 μm, repeated 10 times, resulting in a coating with a total thickness of 19 ± 0.4 μm. The coating was then applied under a reducing atmosphere (5% H2 / N2, oxygen partial pressure <10). -7The coating was obtained by programmed heating (heating to 1100°C at a rate of 2°C / min and holding for 4 hours) under a temperature program. The crystal phase of the coating was monitored by in-situ XRD (Panalytical X'Pert Pro) and it was confirmed that the coating was a single-phase cubic GDC with a grain size of 0.3μm~1.3μm.

[0072] SEM analysis showed that the coating porosity was <1.2% and the interfacial bonding strength was 62 MPa. Transmission electron microscopy (TEM, Thermo Fisher Talos F200X) showed that the interface was atomically bonded with no grain boundary defects.

[0073] The remaining steps are the same as in Example 1.

[0074] Example 3 This embodiment provides an electrolyte coating compatible with a metal-supported anode, comprising: (1) Raw materials High-purity 8 mol% Y2O3-doped zirconium oxide, purity >99.98%, D50 = 22 μm~28 μm, supplier is Tosoh Corporation.

[0075] High-purity 20mol% Gd2O3 doped cerium oxide, purity >99.95%, D50 = 28μm~32μm, supplier is FuelCellMaterials.

[0076] (2) Raw material ratio control The composite powder for the YSZ-GDC composite system comprises YSZ and GDC in a mass ratio of 2.3:1, and 1.3wt% NiO and 0.25wt% nano-ZrO2. The mass fractions of 1.3wt% NiO and 0.25wt% nano-ZrO2 are calculated based on the total mass of the composite powder (containing YSZ, GDC, NiO and nano-ZrO2).

[0077] The CTE was obtained by ball milling using the method described in Example 1. -6 K -1 The composite powder has an ionic conductivity of 0.035 S / cm (800℃) and a fracture toughness of 1.8 MPa·m. 1 / 2 .

[0078] The coating preparation method was the same as the sol-gel method in Example 2, and the remaining steps were the same as in Example 1. The coating thickness obtained in this example was 18.5 μm, and the CTE coefficient was 11.45 × 10⁻⁶. -6 K -1In this embodiment, the maximum thermal stress is 85 MPa, the failure probability is 2.8%, and the power density after 8000 hours is 1.36 W / cm³. 2 The decay rate is 0.35% / 1000h (voltage drops from 1.09V to 1.08V) over 3000 hours.

[0079] The electrolyte coating compatible with metal-supported anodes proposed in this application has at least the following advantages: (1) Significantly reduces thermal stress and improves structural stability By precisely matching the CTE between the electrolyte coating and the metal-supported anode, the thermal stress was reduced from 190 MPa to 100 MPa, a decrease of 47%, compared to the traditional YSC coating. (Comparison of finite element analysis results and thermal stress distribution is provided.) Figure 4 As shown, the stress concentration area of ​​the electrolyte coating in Embodiment 1 of this application is significantly reduced, and the stress distribution is more uniform. This low-stress characteristic effectively prevents electrolyte cracking and interface peeling, and enhances the structural integrity of SOFC during thermal cycling at 600°C to 900°C.

[0080] (2) Significantly improves the quality of interface bonding and enhances durability. The optimized electrolyte has the following main benefits: Improved interface strength: The interface shear strength has been increased from 35MPa in the traditional design to 58MPa~60MPa, an increase of 65%.

[0081] Microstructure stability: After thermal cycling (150 cycles, 600℃~800℃), the interface cracking rate of the electrolyte coating in Example 1 of this application is less than 1%, while the interface cracking rate of the conventional YSC coating is 15%.

[0082] The electrolyte coating of this application extends the mean time between failures (MTTF) of SOFC from 2,800 hours to 6,000 hours, improving durability by 114% and significantly extending battery life.

[0083] (3) Maintain excellent electrochemical performance This application optimizes CTE and interface without sacrificing electrochemical performance. Tests show that the SOFC with the electrolyte coating applied in this application achieves a power density of 1.3 W / cm³ at 800 °C. 2 Compared to the power density of traditional YSC-coated SOFCs (1.15 W / cm²), 2 The voltage has been improved by 13%, and the open-circuit voltage has been stabilized at 1.06V. During long-term operation (2000 hours), the voltage decay rate is only 0.4% / 1000h, which is better than the 1.3% / 1000h of the traditional design, ensuring efficient energy conversion.

[0084] (4) Reduce the risk of thermal mismatch failure and improve reliability The failure probability was quantified using the Weibull model and Monte Carlo simulation. The failure probability of the electrolyte coating in this application is 3.8%, compared to 18% in conventional designs. Figure 4 and Figure 5 The analysis of thermal stress distribution and microstructure further verified the significant reduction in thermal mismatch risk, indicating that the electrolyte coating of this application provides a guarantee for the long-term stable operation of SOFC.

[0085] (5) Support industrialized production and reduce costs The electrolyte coating in this application uses high-purity YSZ / GDC powder (cost reduced to 40 USD / kg) and automated processes (APS deposition efficiency 15m). 2 This reduces production costs by 15% (per hour). A quality control system (CTE testing, density testing, interface strength testing) ensures batch-to-batch performance deviations of <5%, making it adaptable to different metal anodes (Ni-Cr, Fe-Cr) and operating conditions (500℃~900℃), with broad application prospects. Furthermore, the electrolyte coating of this application can extend SOFC life and improve efficiency, reducing SOFC maintenance and replacement costs, and lowering energy consumption and carbon emissions.

[0086] While specific embodiments of this application have been described in detail, this should not be construed as limiting the scope of protection of this application. Various modifications and variations that can be made by those skilled in the art without inventive effort within the scope described in the claims still fall within the scope of protection of this application.

Claims

1. An electrolyte coating compatible with a metal supported anode, characterized in that, comprising a dopant and a matrix; wherein, the matrix comprises at least one of YSZ and GDC; the dopant comprises a combination of nano-oxide and at least one of Al2O3, Sc2O3, MgO, NiO, Co3O4 and Y2O3, the doping amount of the dopant being 0.5wt%-3.5wt%, the doping amount of the nano-oxide being 0.35wt%-0.45wt%; the difference between the thermal expansion coefficient of the electrolyte coating and the thermal expansion coefficient of the metal-supported anode is ≤3.5%.

2. The electrolyte coating compatible with a metal-supported anode of claim 1, wherein, The coefficient of thermal expansion of the electrolyte coating is 11.0 x 10 -6 K -1 -11.8 x 10 -6 K -1 , and the thickness of the electrolyte coating is 15 μm to 25 μm.

3. The electrolyte coating compatible with metal-supported anodes of claim 1, wherein, the electrolyte coating comprises 1.25wt% Al2O3, 0.45wt% Sc2O3, 0.35wt% nano-ZrO2 and the rest YSZ.

4. The electrolyte coating compatible with metal-supported anodes of claim 1, wherein, the electrolyte coating comprises 0.65wt% Y2O3, 1.25wt% MgO, 0.45wt% nano-CeO2 and the rest GDC.

5. The electrolyte coating compatible with metal-supported anodes of claim 1, wherein, the electrolyte coating comprises 1.3wt% NiO, 0.25wt% nano-ZrO2 and a composite matrix comprising YSZ and GDC in a mass ratio of 2.3:

1.

6. The electrolyte coating compatible with metal-supported anodes of claim 1, wherein, the metal-supported anode is a Ni-Cr alloy or a Fe-Cr alloy, the Cr content in the Ni-Cr alloy being 10wt%, the Cr content in the Fe-Cr alloy being 20wt%.

7. A method of producing an electrolyte coating compatible with a metal- supported anode according to any one of claims 1 to 6, characterized in that comprising the following steps: preparing raw material powders of the dopant and the matrix; depositing the raw material powders on the surface of the metal-supported anode by atmospheric plasma spraying or sol-gel method.

8. The preparation method according to claim 7, characterized in that, further comprising subjecting the metal-supported anode to plasma etching treatment and chemical roughening treatment before deposition or spraying, so that the surface roughness of the metal-supported anode is 0.77μm-0.93μm and the contact angle is <25°; wherein the power of the plasma etching treatment is 160W and the time is 6min-8min; the solution of the chemical roughening treatment is 0.1M-0.3M nitric acid solution, the time is 12min-20min and the ultrasonic frequency is 40kHz.

9. The preparation method according to claim 7, characterized in that, the plasma power of the atmospheric plasma spraying is 26kW-27kW, the flow ratio of argon to hydrogen is 43:4.5, the spraying distance is 88.5mm-89.5mm, the powder feeding rate is 35g / min, and the coating thickness after the atmospheric plasma spraying is 22.3μm-23.7μm.

10. The preparation method according to claim 7, characterized in that, the precursor concentration of the sol-gel method is 0.8M-0.9M, the sintering temperature is 1100℃-1150℃, and the holding time is 3.5h-4.5h; the coating thickness obtained by the sol-gel method is 18.5μm-19.5μm.

Images