固体氧化物燃料电池复合阴极的多孔结构对气体扩散阻抗的影响规律

doi:10.15541/jim20250485

摘要/Abstract

摘要： 固体氧化物燃料电池(Solid Oxide Fuel Cell,SOFC)阴极通常是多孔结构的复合材料,以满足气体扩散要求。然而,电极结构与气体扩散阻抗的关系有待进一步揭示。本工作以典型复合阴极镧锶钴铁-掺杂氧化铈(La_0.6Sr_0.4Co_0.2Fe_0.8O_3-_δ-Sm_0.2Ce_0.8O_1.9,LSCF-SDC)为对象,结合交流阻抗(Electrochemical Impedance Spectroscopy,EIS)技术、弛豫时间分布(Distribution of Relaxation Times,DRT)分析与三维(Three-Dimensional,3D)重构方法,揭示阴极结构与气体扩散阻抗的关系。结果显示：在恒电流放电下,扩散阻抗随阴极厚度呈近线性增加;在1.0 A·cm^-2的大电流密度下,受集流体及外部滞流层对传质的限制作用,阻抗-厚度拟合出现了0.113 Ω·cm²的非零截距。微观结构分析表明,随着孔径主峰从~0.3 μm移至~1 μm,气体传输机制从Knudsen扩散向分子扩散根本性转变,导致扩散阻抗大幅降低。孔隙率增加虽有利于传质,却导致三相界面(Triple Phase Boundary,TPB)密度从233.5 μm·μm^-3降至196.7 μm·μm^-3,引起表面交换阻抗升高。综合权衡,添加15%(质量分数)草酸铵可以实现传质能力与反应活性之间的最佳平衡。本研究建立了包含孔隙率、曲折因子及孔径的定量扩散阻抗模型,为SOFC阴极微观结构设计提供了可验证的实验依据和理论支持。

关键词: 气体扩散阻抗, 扩散阻抗模型, 氧还原反应, LSCF-SDC复合阴极, 固体氧化物燃料电池

Abstract: Solid oxide fuel cell (SOFC) cathodes are typically composite materials with porous structure to meet gas diffusion requirements. However, the relationship between electrode structure and gas diffusion impedance remains to be further elucidated. Taking the typical composite cathode lanthanum strontium cobalt ferrite - doped ceria (La_0.6Sr_0.4Co_0.2Fe_0.8O_3-_δ-Sm_0.2Ce_0.8O_1.9, LSCF-SDC) as the research object, this study reveals the relationship between cathode structure and gas diffusion impedance by combining electrochemical impedance spectroscopy (EIS), distribution of relaxation times (DRT) analysis, and three-dimensional (3D) reconstruction methods. The results indicate that under galvanostatic discharge, the diffusion impedance increases nearly linearly with cathode thickness. Specifically, at a high current density of 1.0 A·cm⁻², a non-zero intercept of 0.113 Ω·cm² appears in the impedance-thickness fitting, attributed to the mass transfer limitations imposed by the current collector and the external stagnant layer. Microstructural analysis demonstrates that as the dominant pore size increases from ~0.3 μm to ~1 μm, a fundamental transition in the gas transport mechanism from Knudsen diffusion to molecular diffusion occurs, resulting in a substantial reduction in diffusion impedance. However, while the increased porosity facilitates mass transfer, it leads to a decrease in triple-phase boundary (TPB) density from 233.5 to 196.7 μm·μm^-3, thereby inducing an increase in surface exchange impedance. Comprehensive analysis demonstrates that addition of 15%(in mass) ammonium oxalate achieves an optimal balance between mass transport capability and reaction activity. In this work, a quantitative diffusion impedance model incorporating porosity, tortuosity, and pore size factor is established, providing verifiable experimental evidence and theoretical support for the microstructural design of SOFC cathodes.

Key words: gas diffusion impedance, diffusion impedance model, oxygen reduction reaction, LSCF-SDC composite cathode, solid oxide fuel cell

中图分类号:

TM911

杨艺文, 潘宁, 蒋玉楠, 蒋学鑫, 夏长荣. 固体氧化物燃料电池复合阴极的多孔结构对气体扩散阻抗的影响规律[J]. 无机材料学报, DOI: 10.15541/jim20250485.

YANG Yiwen, PAN Ning, JIANG Yunan, JIANG Xuexin, XIA Changrong. Influence of Porous Structure of Composite Cathode on Gas Diffusion Impedance in Solid Oxide Fuel Cells[J]. Journal of Inorganic Materials, DOI: 10.15541/jim20250485.

参考文献

[1] HAUCH A, KÜNGAS R, BLENNOW P, ,et al. Recent advances in solid oxide cell technology for electrolysis. Science. Recent advances in solid oxide cell technology for electrolysis. Science, 2020, 370(6513): eaba6118.
[2] LI J, CHENG J, ZHANG Y,et al. Advancements in solid oxide fuel cell technology: bridging performance gaps for enhanced environmental sustainability. Advanced Energy and Sustainability Research, 2024, 5(11): 2400132.
[3] KHANAFER K, AL-MASRI A, VAFAI K,et al. Heat up impact on thermal stresses in SOFC for mobile APU applications: thermo-structural analysis. Sustainable Energy Technologies and Assessments, 2022, 52: 102159.
[4] XU A, HUAN D, DAI P,et al. An acidity-regulated double perovskite cathode for efficient and durable power generation of intermediate-temperature solid oxide fuel cells. Journal of Materials Chemistry A, 2024, 12: 19392.
[5] JACOBSON A J.Materials for solid oxide fuel cells.Chemistry of Materials, 2010, 22(3): 660.
[6] STEELE B C H, HEINZEL A. Materials for fuel-cell technologies.Nature, 2001, 414(6861): 345.
[7] PAN N, HAN H, ZHANG Y, XIA C.Study on CO₂ reduction reaction on the surface of Sr₂Fe_1.5Mo_0.5O₆-δ-Sm_0.2Ce_0.8O_1.9 porous composite materials. Journal of Power Sources, 2025, 647: 237364.
[8] HAN H, HU X, ZHANG B,et al. Method to determine the oxygen reduction reaction kinetics via porous dual-phase composites based on electrical conductivity relaxation. Journal of Materials Chemistry A, 2023, 11(5): 2460.
[9] WANG Y, HU B, ZHU Z,et al. Electrical conductivity relaxation of Sr₂Fe_1.5Mo_0.5O₆-δ-Sm_0.2Ce_0.8O_1.9 dual-phase composites. Journal of Materials Chemistry A, 2014, 2(1): 136.
[10] HUSSAIN J, ALI R, AKHTAR M N,et al. Modeling and simulation of planar SOFC to study the electrochemical properties. Current Applied Physics, 2020, 20(5): 660.
[11] GOEL V, COX D, BARNETT S A, THORNTON K.Simulation of the electrochemical impedance in a three-dimensional, complex microstructure of solid oxide fuel cell cathode and its application in the microstructure characterization.Frontiers in Chemistry, 2021, 9: 627699.
[12] ADLER S B, LANE J A, STEELE B C H. Electrode kinetics of porous mixed‐conducting oxygen electrodes.Journal of The Electrochemical Society, 1996, 143(11): 3554.
[13] ZHENG K, LI L, NI M.Investigation of the electrochemical active thickness of solid oxide fuel cell anode.International Journal of Hydrogen Energy, 2014, 39(24): 12904.
[14] SIVASANKARAN V, COMBEMALE L, FRANÇOIS M, CABOCHE G. Ce_0.9Gd_0.1O₂-_x for intermediate temperature solid oxide fuel cells: influence of cathode thickness and anode functional layer on performance. Energies, 2020, 13(17): 4400.
[15] KIM H, EPTING W K, ABERNATHY H W,et al. Advantages of ionic conductors over electronic conductors as infiltrates in solid oxide fuel cell cathodes. International Journal of Hydrogen Energy, 2024, 59: 764.
[16] KIM J W, VIRKAR A V, FUNG K Z,et al. Polarization effects in intermediate temperature, anode‐supported solid oxide fuel cells. Journal of The Electrochemical Society, 1999, 146(1): 69.
[17] WU Z, ZHU P, HUANG Y,et al. A comprehensive review of modeling of solid oxide fuel cells: from large systems to fine electrodes. Chemical Reviews, 2025, 125(4): 2184.
[18] HE A, KIM Y, SHIKAZONO N.Three-dimensional numerical simulation of solid oxide fuel cell cathode based on lattice Boltzmann method with sub-grid scale models.International Journal of Hydrogen Energy, 2017, 42(34): 21886.
[19] HAN H, GUO G, ZHANG S,et al. Reduced surface area for the oxygen reduction reaction in porous electrode via electrical conductivity relaxation. Chemistry, 2024, 30(68): e202402785.
[20] JIANG Y, HUAN D, XIA C.A robust tubular solid oxide fuel cell through bifunctional praseodymium oxide nanocatalyst infiltration.Ceramics International, 2024, 50(7): 12489.
[21] CHEN X J, KHOR K A, CHAN S H.Identification of O₂ reduction processes at yttria stabilized zirconia|doped lanthanum manganite interface.Journal of Power Sources, 2003, 123(1): 17.
[22] LU X, TJADEN B, BERTEI A,et al. 3D Characterization of diffusivities and its impact on mass flux and concentration overpotential in SOFC anode. Journal of The Electrochemical Society, 2017, 164(4): F188.
[23] GUO Y, HE X, HUANG W, WANG M.Microstructure effects on effective gas diffusion coefficient of nanoporous materials.Transport in Porous Media, 2019, 126(2): 431.
[24] ZHANG Y, YAN M, WAN Y,et al. High-throughput 3D reconstruction of stochastic heterogeneous microstructures in energy storage materials. npj Computational Materials, 2019, 5: 11.
[25] ZHANG Y, YAN F, YAN M,et al. High-throughput, super-resolution 3D reconstruction of nano-structured solid oxide fuel cell electrodes and quantification of microstructure-property relationships. Journal of Power Sources, 2019, 427: 112.
[26] RAJ B S, GNANASUNDARAM S, KRISHNAMURTHY B.Modeling the concentration profiles of CO and CO₂ in a direct carbon solid oxide fuel cell—effect of cathode and electrolyte design parameters.Ionics, 2020, 27(2): 729.
[27] TABISH A N, PATEL H C, CHUNDRU P,et al. An SOFC anode model using TPB-based kinetics. International Journal of Hydrogen Energy, 2020, 45(51): 27563.
[28] HUANG K.Gas-diffusion process in a tubular cathode substrate of a SOFC: II: identification of gas-diffusion process using AC impedance method.Journal of The Electrochemical Society, 2004, 151(5): H117.
[29] UR REHMAN H S, COPPOLA N, SINGH A,et al. Gadolinium-doped ceria room-temperature sputtered thin barrier layers in large-area solid oxide fuel cells: influence of their thickness and thickness gradient on the cathodic processes. ACS Applied Energy Materials, 2025, 8(7): 4281.
[30] CAYAN F N, PAKALAPATI S R, ELIZALDE-BLANCAS F,et al. On modeling multi-component diffusion inside the porous anode of solid oxide fuel cells using Fick's model. Journal of Power Sources, 2009, 192(2): 467.
[31] DŽIUGYS A, MAHMOUDI A H, MISIULIS E,et al. Fractal dependence of the packed bed porosity on the particles size distribution. Chaos, Solitons & Fractals, 2022, 159: 112144.
[32] ZHAO F, VIRKAR A V.Dependence of polarization in anode-supported solid oxide fuel cells on various cell parameters.Journal of Power Sources, 2005, 141(1): 79.