Enhancing performance and stability of Sm_0.2Ce_0.8O_1.9-decorated La_0.6Sr_0.4CoO_3−δ composite cathode in flat-tube solid oxide fuel cell

Abstract

The commercialization of solid oxide fuel cells depends on the cathode, which possesses both high catalytic activity and a thermal-expansion coefficient (TEC) that aligns with the electrolyte. Although the cobalt-based cathode La_0.6Sr_0.4CoO₃ (LSC) offers excellent catalytic performance, its TEC is significantly larger than that of the electrolyte. In this study, we mechanically mix Sm_0.2Ce_0.8O_2−δ (SDC) with LSC to create a composite cathode. By incorporating 50wt% SDC, the TEC decreases significantly from 18.29 × 10⁻⁶ to 13.90 × 10⁻⁶ K⁻¹. Under thermal-shock conditions ranging from room temperature to 800°C, the growth rate of polarization resistance is only 0.658% per cycle, i.e., merely 49% that of pure LSC. The button cell comprising the LSC-SDC composite cathode operates stably for over 900 h without Sr segregation, with a voltage growth rate of 1.11%/kh. A commercial flat-tube cell (active area: 70 cm²) comprising the LSC-SDC composite cathode delivers 54.8 W at 750°C. The distribution of relaxation-time shows that the non-electrode portion is the main rate-limiting step. This study demonstrates that the LSC-SDC mixture strategy effectively improves the compatibility with the electrolyte while maintaining a high output, thus rendering it a promising commercial cathode material.

Keywords

solid oxide fuel cell / composite cathode / lanthanum strontium cobalt oxide / samarium-doped cerium oxide / thermal expansion / flat tube

References

[1] Fan LD, Luo WY, Fan QX, et al.. Status and outlook of solid electrolyte membrane reactors for energy, chemical, and environmental applications. Chem. Sci., 2025, 16(166620

[2] Han S, Wei T, Wang SJ, et al.. Recent progresses in the development of tubular segmented-in-series solid oxide fuel cells: Experimental and numerical study. Int. J. Miner., Metall. Mater., 2024, 31(3427

[3] Jang I, Carneiro JSA, Crawford JO, et al.. Electrocatalysis in solid oxide fuel cells and electrolyzers. Chem. Rev., 2024, 124(138233

[4] Liu SM, Deng ZF, Xu GZ, Li BR, Song PX, Wang SR. Commercialization and future development of the solid oxide fuel cell (SOFC) in Europe. Chin. J. Eng., 2020, 42(3278

[5] Wachsman ED, Singhal SC. Solid oxide fuel cell commercialization, research, and challenges. Electrochem. Soc. Interface, 2009, 18(338

[6] Chen RY, Gao Y, Gao JT, et al.. From concept to commercialization: A review of tubular solid oxide fuel cell technology. J. Energy Chem., 2024, 97: 79

[7] Panthi D, Hedayat N, Du YH. Densification behavior of yttria-stabilized zirconia powders for solid oxide fuel cell electrolytes. J. Adv. Ceram., 2018, 7(4325

[8] Ndubuisi A, Abouali S, Singh K, Thangadurai V. Recent advances, practical challenges, and perspectives of intermediate temperature solid oxide fuel cell cathodes. J. Mater. Chem. A, 2022, 10(52196

[9] Kim JH, Baek SW, Lee CB, Park K, Bae J. Performance analysis of cobalt-based cathode materials for solid oxide fuel cell. Solid State Ionics, 2008, 179(27–321490

[10] Hansen KK. A study of La_1−xSr_xCoO_3−δ SOFC cathodes using cone-shaped electrodes and EIS. Int. J. Electrochem. Sci., 2020, 15(1212030

[11] Hayashi H, Saitou T, Maruyama N, Inaba H, Kawamura K, Mori M. Thermal expansion coefficient of yttria stabilized zirconia for various yttria contents. Solid State Ionics, 2005, 176(5–6613

[12] R.V. Kumar and A.P. Khandale, A review on recent progress and selection of cobalt-based cathode materials for low temperature-solid oxide fuel cells, Renewable Sustainable Energy Rev., 156(2022), art No. 111985.

[13] T. Ghorbani-Moghadam, A. Kompany, and M. Golmohammad, The comparative study of doping Cu and Fe on the cathodic properties of La_0.7Sr_1.3CoO₄ layered perovskite compound: to be used in IT-SOFC, J. Alloy. Compd, 926(2022), art No. 166928.

[14] Tai LW, Nasrallah MM, Anderson HU, Sparlin DM, Sehlin SR. Structure and electrical properties of La_1−xSr_xCo_1−yFe_yO₃. Part 2. The system La_1−xSr_xCo_0.2Fe_0.8O₃. Solid State Ionics, 1995, 76(3–4273

[15] Ascolani-Yael J, Montenegro-Hernández A, Liu Q, Barnett SA, Mogni L. Study of La_0.6Sr_0.4Co_1−xFe_xO_3−δ (x = 0.2 & 0.8) electrochemical response as SOFC cathodes and its relation with microstructure. J. Electrochem. Soc., 2019, 166(16F1301

[16] Fukunaga H, Koyama M, Takahashi N, Wen C, Yamada K. Reaction model of dense Sm_0.5Sr_0.5CoO₃ as SOFC cathode. Solid State Ionics, 2000, 132(3–4279

[17] Yang S, He TM, He Q. Sm_0.5Sr_0.5CoO₃ cathode material from glycine-nitrate process: Formation, characterization, and application in LaGaO₃-based solid oxide fuel cells. J. Alloy. Compd., 2008, 450(1–2400

[18] Long QY, Sha R, Wang RH, et al.. Research progress of composite cathode materials for Solid oxide fuel cells. Prog. Nat. Sci.: Mater. Int., 2023, 33(3267

[19] Zhao F, Peng RR, Xia CR. A La_0.6Sr_0.4CoO_3−δ-based electrode with high durability for intermediate temperature solid oxide fuel cells. Mater. Res. Bull., 2008, 43(2370

[20] Liu Y, Zha SW, Liu ML. Nanocomposite electrodes fabricated by a particle-solution spraying process for low-temperature SOFCs. Chem. Mater., 2004, 16(183502

[21] Choi J, Kim B, Shin D. Performance evaluation of Sm_0.5Sr_0.5CoO_3−δ fibers with embedded Sm_0.2Ce_0.8O_1.9 particles as a solid oxide fuel cell composite cathode. J. Eur. Ceram. Soc., 2013, 33(122269

[22] Qi HY, Zhang TH, Qiu P, Liu D, Tu BF, Cheng MJ. Comparison of nanostructured composite cathodes synthesized by liquid self-assembly and nanosolid mechanical-mixing for solid oxide fuel cell. Int. J. Hydrogen Energy, 2022, 47(3515721

[23] Du ZH, Li KY, Zhao HL, Dong X, Zhang Y, Świerczek K. A SmBaCo₂O_5+δ double perovskite with epitaxially grown Sm_0.2Ce_0.8O_2−δ nanoparticles as a promising cathode for solid oxide fuel cells. J. Mater. Chem. A, 2020, 8(2814162

[24] Kim YT, Shikazono N. Investigation of La_0.6Sr_0.4CoO_3−δ-Gd_0.1Ce_0.9O_2−δ composite cathodes with different volume ratios by three dimensional reconstruction. Solid State Ionics, 2017, 309: 77

[25] Zhu CJ, Liu XM, Yi CS, et al.. High-performance PrBaCo₂O_5+δ-Ce_0.8Sm_0.2O_1.9 composite cathodes for intermediate temperature solid oxide fuel cell. J. Power Sources, 2010, 195(113504

[26] Fan HP, Liu ZJ, Wu Y, et al.. Electrochemical performance of La_0.6Sr_0.4CoO_3−δ–Ce_0.9Gd_0.1O_1.95 composite cathode for IT - SOFCs. Int. J. Appl. Ceram. Technol., 2024, 21(1289

[27] Liu M, He CR, Wang WG, Wang JX. Synthesis and characterization of 10Sc1CeSZ powders prepared by a solid–liquid method for electrolyte-supported solid oxide fuel cells. Ceram. Int., 2014, 40(45441

[28] Y. Zhou, T.K. Ye, N.C. Xia, et al., The application of cobalt-free spinel Ni_1.4Mn_1.6O₄ as a cathode in intermediate temperature solid oxide fuel cells, J. Alloy. Compd., 1024(2025), art No. 180288.

[29] Liu AZ, Wang JX, He CR, Miao H, Zhang Y, Wang WG. Synthesis and characterization of Gd_0.1Ce_0.9O_1.95 nanopowder via an acetic-acrylic method. Ceram. Int., 2013, 39(66229

[30] Hu H, Liu ZJ, Huang ZF, et al.. Synthesis of high-performance La_0.6Sr_0.4CoO_3−δ nano-powder prepared via an acetic-acrylic method. J. Ceram. Soc. Jpn., 2023, 131(10837

[31] Y. Zheng, C.H. Zhao, T. Wu, et al., Enhanced oxygen reduction kinetics by a porous heterostructured cathode for intermediate temperature solid oxide fuel cells, Energy AI, 2(2020), art No. 100027.

[32] J. Liu, Z.Y. Hou, Q. Li, G.W. Peng, and Z.T. Tao, Sn-doped cobalt containing perovskite as the cathode for highly active SOFCs, J. Electroanal. Chem., 972(2024), art No. 118643.

[33] Bai JH, Han ZY, Zhou DF, et al.. Preparation of Pr₂NiO_4+δ-La_0.6Sr_0.4CoO_3−δ as a high-performance cathode material for SOFC by an impregnation method. Int. J. Hydrogen Energy, 2023, 48(156076

[34] Cervera RB, Oyama Y, Miyoshi S, Oikawa I, Takamura H, Yamaguchi S. Nanograined Sc-doped BaZrO₃ as a proton conducting solid electrolyte for intermediate temperature solid oxide fuel cells (IT-SOFCs). Solid State Ionics, 2014, 264: 1

[35] Wang HC, Zhu WF, Gong J, et al.. Effect of octahedral occupancy of bimetal-doping and CO₂-induced surface reconstruction on oxygen reduction reaction of cobalt-based perovskite oxides. Chem. Eng. J., 2024, 485: 149770

[36] Joo S, Kim J, Shin J, Lim TH, Kim G. Investigation of a layered perovskite for IT-SOFC cathodes: B-site Fe-doped YBa_0.5Sr_0.5Co_2−xFe_xO_5+δ. J. Electrochem. Soc., 2016, 163(14F1489

[37] Huggins RA. Simple method to determine electronic and ionic components of the conductivity in mixed conductors a review. Ionics, 2002, 8(3300

[38] S.P. Jiang, Solid-state electrochemistry and solid oxide fuel cells: Status and future prospects, Electrochem. Energy Rev., 5(2022), No. 1, art No. 21.

[39] Z.P. Li, Y.F. Ge, Y.H. Xiao, et al., Fabrication and performance investigation of high entropy perovskite (Sr_0.2Ba_0.2Bi_0.2La_0.2Pr_0.2)FeO₃ IT-SOFC cathode material, J. Alloy. Compd., 989(2024), art No. 174357.

[40] Hussain S, Li YP. Review of solid oxide fuel cell materials: Cathode, anode, and electrolyte. Energy Transitions, 2020, 4(2113

[41] Z.W. Lyu, H.Y. Li, Y.G. Wang, and M.F. Han, Performance degradation of solid oxide fuel cells analyzed by evolution of electrode processes under polarization, J. Power Sources, 485(2021), art No. 229237.

[42] Y.J. Gao, M.M. Zhang, L.L. Fan, and Z.T. Tao, Enhancing chemical stability and performance in proton-conducting solid oxide fuel cells through novel composite cathode design, J. Power Sources, 583(2023), art No. 233576.

[43] He S, Saunders M, Chen KF, et al.. A FIB-STEM study of strontium segregation and interface formation of directly assembled La_0.6Sr_0.4Co_0.2Fe_0.8O_3−δ cathode on Y₂O₃-ZrO₂ electrolyte of solid oxide fuel cells. J. Electrochem. Soc., 2018, 165(7F417

[44] Robson JD, Haigh SJ, Davis B, Griffiths D. Grain boundary segregation of rare-earth elements in magnesium alloys. Metall. Mater. Trans. A, 2016, 47(1522

[45] Koo B, Seo J, Kim JK, Jung W. Isovalent doping: A new strategy to suppress surface Sr segregation of the perovskite O₂-electrode for solid oxide fuel cells. J. Mater. Chem. A, 2020, 8(2713763

[46] M. Ghamarinia, A. Babaei, C. Zamani, and H. Aslannejad, Application of the distribution of relaxation time method in electro-chemical analysis of the air electrodes in the SOFC/SOEC devices: A review, Chem. Eng. J. Adv., 15(2023), art No. 100503.

[47] Yang X, Du ZH, Zhang Q, et al.. Effects of operating conditions on the performance degradation and anode microstructure evolution of anode-supported solid oxide fuel cells. Int. J. Miner., Metall. Mater., 2023, 30(61181

[48] J. Xia, C. Wang, X.F. Wang, L. Bi, and Y.X. Zhang, A perspective on DRT applications for the analysis of solid oxide cell electrodes, Electrochim. Acta, 349(2020), art No. 136328.

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