@article {1165, title = {Scaleup and manufacturability of symmetric-structured metal-supported solid oxide fuel cells}, journal = {Journal of Power Sources}, volume = {489}, year = {2021}, pages = {229439}, abstract = {Metal-supported solid oxide fuel cells with symmetric architecture, having metal supports on both sides of the cell, are scaled up from button cell size to large 50~cm2 active area cell size. The cells remain flat after sintering assisted by the symmetric structure. Equivalent performance is achieved for button cells and large cells, and thermal cycling and redox cycling tolerance are demonstrated for the large cells. The catalyst infiltration process is improved to enable high-throughput manufacturing. The cumbersome lab-scale molten nitrate infiltration process is replaced with a room-temperature process in which a shelf-stable aqueous solution of nitrate salts is applied to the cell by spraying, painting, or other scalable techniques. A fast-ramp thermal conversion of the nitrate salts to the final oxide catalyst composition is implemented, allowing many infiltration cycles to be accomplished in a single work shift. Increasing the number of infiltration cycles from 5 to 10 led to an increase in peak power density from approximately 0.3 to 0.52~W~cm-2.}, keywords = {infiltration, Metal-supported, Scale up, SOFC}, issn = {0378-7753}, doi = {https://doi.org/10.1016/j.jpowsour.2020.229439}, url = {https://www.sciencedirect.com/science/article/pii/S0378775320317225}, author = {Emir Dogdibegovic and Yuan Cheng and Fengyu Shen and Ruofan Wang and Boxun Hu and Michael C. Tucker} } @article {1060, title = {Approaches for co-sintering metal-supported proton-conducting solid oxide cells with Ba(Zr,Ce,Y,Yb)O3-δ electrolyte}, journal = {International Journal of Hydrogen Energy}, volume = {44}, year = {2019}, month = {05/2019}, pages = {13768-13776}, abstract = {

Published on May 21st, 2019. Proton conducting oxide electrolyte materials could potentially lower the operating temperature of metal-supported solid oxide cells (MS-SOCs) to the intermediate range 400 to 600\ {\textdegree}C. The porous metal substrate provides the advantages of MS-SOCs such as high thermal and redox cycling tolerance, low-cost of structural materials, and mechanical ruggedness. In this work, the viability of co-sintering fabrication of metal-supported proton conducting solid oxide cells using BaZr1-x-yCexYyO3-δ (BZCY) is investigated. BZCY ceramics are sintered at 1450\ {\textdegree}C in reducing environment alone and supported on FeCr alloy metal support, and key characteristics such as Ba loss, sintering behavior, and chemical compatibility with metal support are determined. Critical challenges are identified for this fabrication approach, including: Contamination of the electrolyte with Si and Cr from the metal support, incomplete electrolyte sintering, and evaporation of electrolyte constituents. Various approaches to overcome these limitations are proposed, and preliminary assessment indicates that the use of barrier layers, low-Si-content stainless steel, and sintering aids warrant further development.

}, doi = {10.1016/j.ijhydene.2019.03.181}, url = {http://www.sciencedirect.com/science/article/pii/S0360319919312108}, author = {Ruofan Wang and Grace Y. Lay and Dong Ding and Tianli Zhu} } @article {1061, title = {Assessment of co-sintering as a fabrication approach for metal-supported proton-conducting solid oxide cells}, journal = {Solid State Ionics}, volume = {332}, year = {2019}, month = {04/2019}, pages = {25-33}, abstract = {

Published on April 1st, 2019. Proton conducting oxide electrolyte materials could potentially lower the operating temperature of metal-supported solid oxide cells (MS-SOCs) to the intermediate range 400 to 600 {\textdegree}C. The porous metal substrate provides the advantages of MS-SOCs such as high thermal and redox cycling tolerance, low-cost of structural materials, and mechanical ruggedness. In this work, viability of co-sintering fabrication of metal-supported proton conducting solid oxide cells is investigated. Candidate proton conducting oxides including perovskite oxides BaZr0.7Ce0.2Y0.1O3-δ, SrZr0.5Ce0.4Y0.1O3-δ, and Ba3Ca1.18Nb1.82O9-δ, pyrochlore oxides La1.95Ca0.05Zr2O7-δ and La2Ce2O7, and acceptor doped rare-earth ortho-niobate La0.99Ca0.01NbO4 are synthesized via solid state reactive or sol-gel methods. These ceramics are sintered at 1450 {\textdegree}C in reducing environment alone and supported on Fe-Cr alloy metal support, and their key characteristics such as phase formation, sintering property, and chemical compatibility with metal support are determined. Most electrolyte candidates suffer from one or more challenges identified for this fabrication approach, including: phase decomposition in reducing atmosphere, evaporation of electrolyte constituents, contamination of the electrolyte with Si and Cr from the metal support, and incomplete electrolyte sintering. In contrast, La0.99Ca0.01NbO4 is found to be highly compatible with the metal support and co-sintering processing in reducing atmosphere. A metal-supported cell is fabricated with La0.99Ca0.01NbO4 electrolyte, ferritic stainless steel support, Pt air electrode and nanoparticulate ceria-Ni hydrogen electrocatalyst. The total resistance is 50 Ω{\textperiodcentered}cm2 at 600 {\textdegree}C. This work clearly demonstrates the challenges, opportunities, and breakthrough of metal-supported proton-conducting solid oxide cells by co-sintering fabrication.

}, issn = {0167-2738}, doi = {10.1016/j.ssi.2019.01.004}, url = {http://www.sciencedirect.com/science/article/pii/S0167273818309263}, author = {Ruofan Wang and Conor Byrne and Michael C. Tucker} } @article {1185, title = {Ferritic stainless steel interconnects for protonic ceramic electrochemical cell stacks: Oxidation behavior and protective coatings}, journal = {International Journal of Hydrogen Energy}, volume = {44}, year = {2019}, pages = {25297-25309}, abstract = {Protonic ceramic fuel or electrolysis cells (PCFC/PCEC) have shown promising performance at intermediate temperatures. However, these technologies have not yet been demonstrated in a stack, hence the oxidation behavior of the metallic interconnect under relevant operating environments is unknown. In this work, ferritic stainless steels 430 SS, 441 SS, and Crofer 22 APU were investigated for their use as interconnect materials in the PCFC/PCEC stack. The bare metal sheets were exposed to a humidified air environment in the temperature range from 450~{\textdegree}C to 650~{\textdegree}C, to simulate their application in a PCFC cathode or PCEC anode. Breakaway oxidation with rapid weight gain and Fe outward diffusion/oxidation was observed on all the selected stainless steel materials. A protective coating is deemed necessary to prevent the metallic interconnect from oxidizing. To mitigate the observed breakaway oxidation, state-of-the-art protective coatings, Y2O3, Ce0.02Mn1.49Co1.49O4, CuMn1.8O4 and Ce/Co, were applied to the stainless steel sheets and their oxidation resistance was investigated. Dual atmosphere testing further validated the effectiveness of the protective coatings in realistic PCFC/PCEC environments, with a hydrogen gradient across the interconnect. Several combinations of metal and coating material were found to be viable for use as the interconnect for PCFC/PCEC stacks.}, keywords = {Dual atmosphere, Interconnect oxidation, Oxidation, Protective coatings, Protonic ceramic electrolysis cell, Protonic ceramic fuel cell}, issn = {0360-3199}, doi = {https://doi.org/10.1016/j.ijhydene.2019.08.041}, url = {https://www.sciencedirect.com/science/article/pii/S0360319919329581}, author = {Ruofan Wang and Zhihao Sun and Jung-Pyung Choi and Soumendra N. Basu and Jeffry W. Stevenson and Michael C. Tucker} } @article {1191, title = {Progress in Metal-Supported Solid Oxide Fuel Cells and Electrolyzers with Symmetric Metal Supports and Infiltrated Electrodes}, journal = {ECS Transactions}, volume = {91}, year = {2019}, month = {07/2019}, pages = {877{\textendash}885}, abstract = {The LBNL metal-supported solid oxide cell architecture contains zirconia electrolyte and porous backbones co-sintered between porous stainless steel supports. Advantages of this design include low-cost structural materials, mechanical ruggedness, excellent tolerance to redox cycling, and extremely fast start-up capability. With infiltrated catalysts, high performance is also achieved: 1.5 W/cm2 with hydrogen fuel and 1.3 W/cm2 with internal reforming of ethanol fuel at 700 {\textdegree}C; 2.6 A/cm2 electrolysis current density at 1.3V and 50\% steam/50\% hydrogen at 700{\textdegree}C. Recent approaches to mitigating catalyst coarsening and Cr deposition within the cathode stabilize the microstructure during operation. The degradation rate is improved to 2.3\% kh-1 at 700{\textdegree}C in fuel cell mode. Electrolysis operation, however, results in higher degradation rate. Preliminary effort to fabricate metal-supported cells with proton conducting electrolyte is successful for La0.99Ca0.01NbO4 electrolyte, and specific challenges for BaZr0.7Ce0.2Y0.1O3-δ electrolyte are determined.}, keywords = {BaZr0.7Ce0.2Y0.1O3-δ electrolyte, HTE, La0.99Ca0.01NbO4 electrolyte, SOEC}, doi = {10.1149/09101.0877ecst}, url = {https://doi.org/10.1149/09101.0877ecst}, author = {Emir Dogdibegovic and Fengyu Shen and Ruofan Wang and Ian Robinson and Grace Y Lau and Michael C Tucker} }