Cobalt-based modified fine-particle-size solid oxide fuel cell cathode material
Through the composite and interface design of modified cathode material and electrolyte, the stability and preparation complexity of SOFC cathode material during high temperature operation are solved, and efficient and stable battery performance is achieved.
Patent Information
- Application Number
- CN202510361736.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-26
- Publication Date
- 2025-07-08
AI Technical Summary
The existing SOFC cathode materials have problems such as poor interface stability, mismatch of thermal expansion coefficients and complex preparation processes during high-temperature operation, which limit their application in medium and high-temperature solid oxide fuel cells.
LaCo0.6Ni0.4O3-δ (LCN) is used as the cathode active material, and the microstructure and interface design are optimized to simplify the preparation process by recombining it with a fine-grain SDC framework and introducing a GDC barrier layer.
It improves oxygen reduction reaction activity, reduces polarization resistance, enhances interface stability, reduces thermal stress, simplifies the production process, and improves battery efficiency and stability.
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Figure CN120280499A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of solid oxide fuel cells (SOFCs), and more particularly, to a cobalt-based modified fine-particle-size solid oxide fuel cell cathode material. Background Art
[0002] In SOFCs, the cathode plays a crucial role. It is responsible for the oxygen reduction reaction (ORR), which involves the transport of oxygen ions through the electrolyte, adsorption on the cathode surface, and subsequent electron transfer to form water. This multi-step process is affected by the electronic and ionic conductivities of the cathode and its electrocatalytic activity.
[0003] Perovskite oxides have been shown to have both stable structural strength properties and good mixed conductivity properties in high-temperature working environments and are widely used as materials for preparing high-temperature cathodes. Typical ones are cobalt-based perovskites La 1-x Sr x Co 1-y Fe y O 3-δ (LSCF), Ba 1-x Sr x Co 1-y Fe y O 3-δ (BSCF), and PrBaCo2O 5+δ (PBC). These cathode materials can provide excellent ORR activity; however, currently available high-temperature cathode materials usually interact with yttria-stabilized zirconia (YSZ), a high-quality electrolyte with wide application and commerciality. Therefore, research on simultaneously ensuring good cathode activity and a dense and stable electrolyte layer has been successively carried out, and a variety of relatively mature methods have been proposed for modifying the cathode. It is basically centered around selecting materials with good ionic conductivity and good physical and chemical compatibility with YSZ as a buffer to achieve the smooth composite of the active cathode and the electrolyte and low resistance on the electrochemical reaction path, such as selecting gadolinium-doped ceria (GDC), samarium-doped ceria (SDC), and other materials. The composite means are roughly the following methods:
[0004] (1) Mechanical mixing method
[0005] By mixing the cathode active material powder with GDC / SDC and preparing it into an electrode slurry, it is subsequently coated on the battery substrate. The mechanical mixing compensates for the low ionic conductivity of the perovskite oxide and significantly solves the problem of reduced electrode stability caused by poor mechanical compatibility during continuous high-temperature use of the cathode. However, it still has general performance due to the side reaction between the perovskite oxide and YSZ and the relatively few three-phase reaction interfaces. Reference: Kongfa Chen, Zhe Lü, Xiangjun Chen, Na Ai, Xiqiang Huang, Xiaobo Du, Wenhui Su, Development of LSM-based cathodes for solid oxide fuel cells based on YSZ films, Journal of Power Sources, Volume 172, Issue 2, 2007, Pages 742-748.
[0006] (2) Skeleton impregnation method
[0007] Taking the example of Zhao et al. sintering a porous SDC skeleton on an SDC substrate and impregnating LSC, the unique structure (figure) produced by its preparation achieved strong thermal stability. After more than 20 thermal cycles of 500-800 °C and 10 thermal cycles from room temperature to 800 °C, no increase in ASR was observed. However, this simple structure is only applicable to the scenario where the perovskite oxide and the electrolyte have good high-temperature stability, and there are side reactions for combining LCN (cathode active material) and YSZ (electrolyte) that are widely used commercially at the same time. Reference: Fei Zhao, Ranran Peng, Changrong Xia, A La0.6Sr0.4CoO3-δ-based electrode with high durability for intermediate temperature solid oxide fuel cells, Materials Research Bulletin, Volume 43, Issue 2, 2008, Pages 370-376.
[0008] (3) Multi-round alternating impregnation method
[0009] By alternately impregnating perovskite oxides and GDC / SDC to achieve compatibility matching, a very large number of triple-phase reaction interfaces (TCP) are introduced, resulting in extremely excellent electrochemical performance. However, compared with other methods, the preparation process is cumbersome and has higher requirements for the preparation environment, making it difficult to meet possible production needs to a certain extent. Reference: Nanqi Duan, Jiajun Yang, Minrui Gao, Bowen Zhang, Jing-Li Luo, Yanhai Du, Minghou Xu, Lichao Jia, Bo Chi, Jian Li, Multi-functionalities enabled fivefold applications of LaCo0.6Ni0.4O3-δ in intermediate temperature symmetrical solid oxide fuel / electrolysis cells, Nano Energy, Volume 77, 2020, 105207.
[0010] (4) Introduce a barrier layer
[0011] By adding a barrier layer prepared by SDC / GDC in advance between the electrolyte and the cathode material to achieve the matching of physical and chemical compatibility, the stability of the cathode in the high-temperature continuous use environment is greatly improved, and at the same time, a good overall resistance performance can be achieved. However, side reaction phases will also appear at the contact interface between the perovskite oxide and GDC during the operation of the battery, resulting in an increase in the area specific resistance. This is also the part that needs to be improved in this preparation method. Reference: De Vero, J.C., Bagarinao, K.D.-, Kishimoto, H., Ishiyama, T., Yamaji, K., Horita, T., & Yokokawa, H. (2017). Effect of Gd-Doped Ceria Interlayer Microstructure on the Interdiffusion Behavior Between La0.6Sr0.4Co0.2Fe0.8O3-δ Cathodes and Yttria-Stabilized Zirconia Electrolytes. ECS Transactions, 78(1), 971–981.
[0012] In summary, although existing cathode modification methods have achieved certain results in improving the compatibility between perovskite oxides and YSZ electrolytes and reducing the area specific resistance, it is still difficult to balance productivity and the long-term performance of the battery. Therefore, a new solution for optimizing the cathode composition, microstructure, and interface design is needed to achieve efficient and stable cathode performance and meet relatively simple preparation requirements. Summary of the Invention
[0013] (1) Technical Problems to be Solved by the Invention
[0014] Existing SOFC cathode materials (such as LSCF, BSCF, etc.) have problems such as poor interface stability, mismatch of thermal expansion coefficient with the electrolyte, and complex preparation processes during high-temperature operation, which limit their practical applications in medium- and high-temperature (700 - 800 °C) solid oxide fuel cells.
[0015] Therefore, the present invention aims to solve the following technical problems:
[0016] Improve the oxygen reduction reaction (ORR) activity of the cathode material, reduce the cathode polarization resistance, and thus improve the overall efficiency of the battery.
[0017] Improve the interface stability between the cathode and the electrolyte, reduce interface side reactions, and improve the long-term stability of the battery.
[0018] Optimize the thermal expansion coefficient of the cathode material to match that of the electrolyte material and reduce thermal stress during high-temperature operation.
[0019] Simplify the preparation process, reduce production costs, and improve the practical production adaptability of the material.
[0020] (2) Technical Solutions for Solving the Technical Problems
[0021] The present invention achieves the above objectives through the following technical solutions:
[0022] On the one hand, the present invention provides a cobalt-based modified fine-particle-size solid oxide fuel cell cathode material.
[0023] Material Selection: The present invention selects LaCo 0.6 Ni 0.4 O 3-δ (LCN) as the cathode active material and optimizes its electronic and ionic conductivity through element doping (such as Ni, Fe, etc.).
[0024] Microstructure Design: The impregnation method is used to composite LCN with a fine-particle-size SDC (samarium-doped ceria) skeleton to form a cathode structure with a wide three-phase boundary (TPB), significantly increasing the electrochemical active surface area.
[0025] Interface stability optimization: Introduce a GDC (gadolinium-doped ceria) barrier layer between the cathode and the YSZ electrolyte to optimize the interface structure, reduce interfacial side reactions, and improve the chemical stability between the cathode and the electrolyte.
[0026] Thermal expansion coefficient matching: By adjusting the composition and microstructure of the cathode material, make its thermal expansion coefficient match that of the YSZ electrolyte to reduce thermal stress during high-temperature operation.
[0027] In a second aspect, the present invention provides a method for preparing the cobalt-based modified fine-particle-size solid oxide fuel cell cathode material described in the first aspect.
[0028] SDC skeleton preparation: Prepare a porous SDC skeleton by screen printing.
[0029] Impregnation method for composite: Immerse the LCN precursor solution in the SDC skeleton, and after drying, calcination and other treatments, form an LCN-SDC composite cathode.
[0030] Barrier layer introduction: Coat a layer of GDC slurry between the cathode and the YSZ electrolyte, and form a barrier layer after sintering.
[0031] Cell assembly and sintering: Assemble the prepared cathode, YSZ electrolyte, Ni-YSZ anode, etc. into a single cell, and after subsequent treatments such as sintering, obtain a high-performance SOFC single cell.
[0032] In a third aspect, the present invention provides a solid oxide fuel cell, including the cobalt-based modified fine-particle-size cathode material described in the first aspect of the present invention, and a matched YSZ electrolyte and Ni-YSZ anode.
[0033] (3) Beneficial effects
[0034] The cobalt-based modified fine-particle-size cathode material and its preparation method of the present invention have the following beneficial effects:
[0035] Improve ORR activity: By optimizing the electronic and ionic conductivity of the cathode material and constructing a wide three-phase boundary (TPB), the oxygen reduction reaction activity of the cathode is significantly improved, the cathode polarization resistance is reduced, and the overall efficiency of the cell is improved.
[0036] Enhance interface stability: Introducing a GDC barrier layer effectively solves the chemical compatibility problem between the cathode material and the YSZ electrolyte, reduces interfacial side reactions, and improves the long-term stability of the cell.
[0037] Optimize thermal expansion coefficient matching: By adjusting the composition and microstructure of the cathode material, optimize its thermal expansion coefficient, reduce thermal stress during high-temperature operation, and enhance the thermal / mechanical stability of the cell.
[0038] Simplified preparation process: By using simple preparation methods such as the impregnation method, good contact between the cathode active material and the electrolyte is achieved, improving the electrochemical performance of the battery, having high production feasibility, and reducing production costs.
[0039] Enhanced battery performance: Under medium and high temperature (700 - 800 °C) conditions, the power density, electrolysis current density, and stability of the battery are significantly improved, meeting the actual application requirements of distributed power generation, combined heat and power systems, etc. Description of the drawings
[0040] Figure 1 is a schematic diagram of the cathode structure of the present invention
[0041] In the figure: 1. GDC barrier layer; 2. SDC cathode skeleton; 3. LCN impregnation modification layer. Detailed implementation manners
[0042] In order to make the objectives, technical solutions, and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.
[0043] Figure 1 Shows a basic implementation manner of the present invention. This embodiment provides a preparation method and a schematic structure diagram of a cobalt-based modified fine-particle solid oxide fuel cell (SOFC) cathode material. As Figure 1 shown, the cathode material consists of the following parts:
[0044] GDC barrier layer 1: A layer of GDC (gadolinium-doped ceria) barrier layer is introduced between the cathode and the YSZ electrolyte to optimize the interface stability and reduce interfacial side reactions.
[0045] SDC skeleton layer 2: As the support structure of the cathode, a porous SDC (samarium-doped ceria) skeleton prepared by the screen printing method has good ionic conductivity and thermal stability.
[0046] Cobalt-based active material layer 3: By impregnating the LaCo 0.6 Ni 0.4 O 3-δ (LCN) precursor solution into the SDC skeleton, and after drying and calcination treatments, a uniformly distributed cobalt-based active material layer is formed, which has excellent oxygen reduction reaction (ORR) activity.
[0047] Example 1: Preparation of cobalt-based modified fine-particle SOFC cathode material
[0048] (1) Integrated preparation of the anode support and the YSZ electrolyte layer
[0049] An integrated structure of an anode support and a YSZ electrolyte layer is prepared by the tape-casting method. NiO powder and YSZ powder are mixed in a certain proportion (such as 60% NiO + 40% YSZ), and deionized water and organic additives (such as PVB-98 or PVA and other similar substances) are added. At the same time, an appropriate amount of YSZ powder is uniformly mixed with the above mixture to ensure the uniform distribution of the electrolyte layer. After being uniformly mixed by ball milling, a green body with a thickness of about 1.2 mm is prepared by tape-casting, and the thickness of the YSZ electrolyte layer is about 20 μm. The green body is dried at 80 °C for 12 hours and then sintered at 1400 °C for 4 hours to obtain an integrated structure of the anode support and the YSZ electrolyte layer. The sintered structure has good conductivity, mechanical strength, and ionic conductivity.
[0050] (2) Preparation of the GDC barrier layer
[0051] A layer of GDC slurry is coated on the surface of the sintered YSZ electrolyte layer. The GDC slurry is composed of GDC powder, a small amount of ethanol, and organic additives (such as polyethylene glycol, triethanolamine, dibutyl phthalate, etc.). The GDC slurry is uniformly coated on the surface of the YSZ electrolyte layer by screen printing to form a GDC barrier layer with a thickness of about 6 μm. After coating, it is sintered at 1000 °C for 1 hour. This barrier layer effectively optimizes the interfacial stability between the cathode and the YSZ electrolyte and reduces interfacial side reactions.
[0052] (3) Preparation of the SDC skeleton layer
[0053] A porous SDC skeleton is prepared by screen printing. SDC powder is mixed with deionized water and organic additives (such as ethyl cellulose - turpentine alcohol and other similar substances), and after being uniformly mixed by ball milling, an SDC slurry is prepared. The SDC slurry is uniformly coated on the surface of the GDC barrier layer by screen printing to form a porous SDC skeleton with a thickness of about 50 μm. After coating, it is sintered at 1200 °C for 2 hours to obtain an SDC skeleton with good ionic conductivity and thermal stability.
[0054] (4) Impregnation of the cobalt-based active material
[0055] The LaCo 0.6 Ni 0.4 O 3-δ (LCN) precursor solution (such as nitrate solution) is uniformly impregnated into the SDC skeleton for 1 hour. Subsequently, the impregnated skeleton is dried at 80 °C for 12 hours to remove organic solvents. The dried skeleton is calcined at 800 °C for 2 hours to convert the LCN precursor into an active cobalt-based material, forming a uniformly distributed cobalt-based active material layer.
[0056] (5) Performance testing
[0057] The test results show that the maximum power density of the battery reaches 1.3 W / cm² at 750 °C 2 , and after continuous operation for 100 hours, the performance degradation rate is less than 5%.
[0058] Example 2: Comparison of SDC skeletons with different particle sizes
[0059] To verify the influence of the fine-particle-size SDC skeleton on the cathode performance, skeletons were prepared using SDC powders with particle sizes of 0.5 μm and 1.5 μm, respectively. Through the same impregnation, drying, and calcination processes, two cathode materials with different particle sizes were prepared.
[0060] The test results show that the maximum power density of the cathode material with a fine-particle-size (0.5 μm) SDC skeleton is 1.46 W / cm² at 750 °C 2 , while the maximum power density of the cathode material with a coarse-particle-size (1.5 μm) SDC skeleton is only 1.22 W / cm² 2 . The fine-particle-size SDC skeleton significantly increases the electrochemically active surface area of the cathode, thus improving the overall performance of the battery.
Claims
1. A cobalt-based modified fine-particle-size solid oxide fuel cell cathode material, characterized in that, The cathode material includes: Cobalt-based active material LaCo 0.6 Ni 0.4 O 3-δ , where δ is the oxygen vacancy concentration; Fine-grained SDC framework: composed of samarium-doped ceria, with a particle size range of 0.1 - 1.0 microns; GDC barrier layer: composed of gadolinium-doped ceria, with a thickness of 5 - 20 microns, located between the cathode and the electrolyte.
2. The cobalt-based modified fine-particle-size solid oxide fuel cell cathode material according to claim 1, characterized in that, The particle size range of the SDC framework is 0.3 - 0.8 microns.
3. The cobalt-based modified fine-particle-size solid oxide fuel cell cathode material according to claim 1, characterized in that, The thickness of the GDC barrier layer is 10 - 15 microns.
4. The cobalt-based modified fine-particle-size solid oxide fuel cell cathode material according to claim 1, characterized in that, The cobalt-based active material is uniformly distributed in the SDC framework by the impregnation method, and the impregnation time is 0.5 - 2 hours.
5. The preparation method of the cobalt-based modified fine-particle-size solid oxide fuel cell cathode material according to claim 1, wherein, It includes the following steps: Prepare the SDC framework: Mix SDC powder with deionized water and an organic additive, and prepare a porous SDC framework by screen printing. The sintering temperature is 1000 - 1300 °C, and the sintering time is 1 - 4 hours; Impregnating cobalt-based active material: uniformly impregnating the LaCo 0.6 Ni 0.4 O 3-δ precursor solution into the SDC framework, drying, and then calcining at 700 - 900 °C for 1 - 3 hours; Coat the GDC barrier layer: Coat the GDC slurry on the surface of the calcined SDC framework. The sintering temperature is 900 - 1100 °C, and the sintering time is 0.5 - 2 hours.
6. The preparation method according to claim 5, characterized in that, In the preparation process of the SDC framework, the organic additive is terpineol.
7. The preparation method according to claim 5, characterized in that, The GDC slurry is composed of GDC powder, deionized water, and ethanol.
8. A solid oxide fuel cell, characterized in that, It includes the cobalt-based modified fine-grained cathode material described in any one of claims 1 - 4, and a YSZ electrolyte and a Ni-YSZ anode that cooperate with it.