Papers by Keyword: IT-SOFC

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Authors: Francesca Zurlo, Elisabetta di Bartolomeo, A. d’Epifanio, Valeria Felice, Isabella Natali Sora, S. Licoccia
Abstract: A “cobalt free” cathode material with stoichiometric composition La0.8Sr0.2Fe0.8Cu0.2O3 (LSFCu) was specifically developed for La0.8Sr0.2Ga0.8Mg0.2O3 (LSGM) electrolyte. The chemical stability with LSGM electrolyte was investigated by structural and morphological analysis. The electrochemical properties of LSFCu dense pellets were investigated in the temperature range 600–750°C by electrochemical impedance spectroscopy (EIS). LSFCu/LSGM/LSFCu symmetrical cells were prepared and Area Specific Resistance (ASR) values, directly depending on the rate limiting step of the oxygen reduction reaction, were evaluated. Fuel cells were prepared using LSFCu as cathode material on LSGM pellet and electrochemical tests were performed and compared to similar fuel cells prepared by using commercial La0.6Sr0.4Fe0.8Co0.2O3(LSFCo). The maximum current density and power density recorded for LSFCu and LSFCo were comparable demonstrating that Cu can be used as substitutes Co.
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Authors: Jie Zhao, Ling Long Kong, Chen Li, Yong Chang Ma
Abstract: To develop novel cathode materials with high electrical performances for intermediate temperature solid oxide fuel cells (IT-SOFCs) and optimize the preparation process, perovskite-type oxides Pr1-x-ySrxCayCo1-zFezO3-δ (x=0.1, 0.2; y=0.1, 0.2; z=0.2, 0.3, 0.4; denoted as PSCCF-81182, PSCCF-72173 and PSCCF-62264) were prepared by solid state reaction. The formation process, phase structure and microstructure of the prepared samples were measured using TG-DTA, FT/IR, XRD and SEM techniques. The mixed conductivity of the samples was measured using DC four-terminal method in the range of 150-950 °C. Chemical state of the elements was measured by XPS experiments. The results show that the prepared samples PSCCF-81182, PSCCF-72173 and PSCCF-62264 exhibit a single phase with cubic perovskite structure after sintered at 1200 °C for 6 h. The mixed conductivity of the samples increases with temperature up to a maximum value, and then decreases. At lower temperature, the conductivity follows small polaron hopping mechanism. The negative temperature dependence occurring at higher temperature is due to the creation of oxygen vacancies for charge balance. At intermediate temperature (600-800 °C), the mixed conductivity values of the prepared samples are all much higher than 100 S•cm-1,and can meet the demand of cathode materials for IT-SOFC. XPS tests show that Co and Fe elements in PSCCF-72173 are all of + 3 and + 4 valence. Absorbed oxygen can also be found from the XPS patterns, which is related to the concentration of oxygen vacancies in the perovskite-type oxides.
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Authors: Jun Fang Yang, Ji Gui Cheng, Qiu Mei Jiang, Jian Feng Gao
Abstract: Pr1.2Sr0.8NiO4 (PSNO) and Sm0.2Ce0.8O1.9 (SCO) powders were synthesized by a glycine-nitrate process and a gel-casting process, respectively. Pr1.2Sr0.8NiO4-x Sm0.2Ce0.8O1.9 (x=0, 25, 50) composite cathode materials were prepared by mechanically mixing the two powders. The particle size of the synthesized PSNO and SCO powders is about 100nm and 50nm, respectively. PSNO and SCO have a good chemical compatibility. Area specific resistance value for the Pr1.2Sr0.8NiO4-x Sm0.2Ce0.8O1.9 (x=25, 50) composite cathode on SCO electrolyte is 0.087 and 0.076Ωcm2 at 750°C, which indicates Pr1.2Sr0.8NiO4-Sm0.2Ce0.8O1.9 composite materials may be a promising cathode material for intermediate temperature solid oxide fuel cell (IT-SOFC).
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Authors: Rui Li, Xiu Hua Chen, Wen Hui Ma, Jie Xing, Jian Jun Yang, Jie Yu
Abstract: The LSCM (La0.7Sr0.3Cr0.5Mn0.5O3-δ) powders were synthesized by glycine-nitrate process (GNP). An anode functional layer (AFL) LSCM was fabricated on an porous NiO-LSCM anode substrate by slurry spin coating. The effect of pore-former, sintering temperature and sintering time on the quality of thin film was investigated. The film with good apparent morphology was obtained when the operating parameters were fixed as follows: the pore-former is ethyl cellulose, the content of ethyl cellulose is 5 wt.%, the sintering temperature is 1000 °C and the sintering time is 4 h.
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Authors: Flávia M. Aquino, Fernando M.B. Marques, Dulce M.A. Melo, Daniel A. de Macedo, Aleksey A. Yaremchenko, Filipe M. Figueiredo
Abstract: The development of electrochemical devices towards clean energy generation has been intensified in the last years. In this context, fuel cells, and especially intermediate temperature solid oxide fuel cells (IT-SOFC) have received much attention. Perovskite type materials of composition Ba1-xSrxCo1-yFeyO3-δ, doped or not with rare earth ions, have been quite promising because they have good ionic conductivity and operate at relatively low temperatures (500 750 °C). In this study, powders of compositions (BaSr)0.5Sm0.5Co0.8Fe0.2O3-δ (BSSCF) and (BaSr)0.5Nd0.5Co0.8Fe0.2O3-δ (BSNCF) were prepared using commercial gelatin powder as a polymerizing agent for its use as cathode. The as-prepared powders were calcined at 1000 oC and characterized by X-ray diffraction and scanning electron microscopy. Screen-printed symmetrical cells were sintered 1150 °C and studied by electrochemical impedance spectroscopy in order to assess the cathode kinetics for the oxygen reduction reaction. The best area specific resistance was found for the BSSCF cathode sintered at 1150 °C for 4 h (0.157 Ω.cm2 at 750 °C), demonstrating that this novel composition is suitable for application as SOFC cathode material. key words: Cathode, microstructure, impedance spectroscopy, IT-SOFC.
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Authors: Charusporn Mongkolkachit, Suda Wanakitti
Abstract: The La0.56Sr0.4Co0.2Fe0.8O3-δ (LSCF) perovskite cathode, substituted by Sr and Fe at the A and B sites, respectively, is a good candidate for intermediate temperature solid oxide fuel cell (IT-SOFC) applications. The powders were prepared by sol-gel method using various metal nitrates as starting materials. The adipic acid was used as a chelating agent and ethylene glycol as a dispersant. The gel precursor was heated at 700 °C for 4 h to obtain LSCF cathode powders. X-ray diffraction pattern showed the single phase of the perovskite structure. The microstructure of LSCF materials was observed by scanning electron microscopy which was loosely aggregated and could be ground easily into fine powders. The average particle size of the powders was found to be around 80-200 nm. TGA/DTA techniques exhibited the weight loss after high temperature process. It was found that no weight loss after 550 °C suggests the completion of combustion process.
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Authors: Sruthi Kattamanchi, Rathinam Vasudevan, Ramasamy Jayavel, Singaravelu Ganesan
Abstract: The Gd substituted BaCe0.8Y0.1O3-δ nanocomposites were prepared by a modified Pechini route and then the prepared material was subjected to conventional sintering at 1400°C. The powder XRD results show that the material exhibit orthorhombic crystalline structure and the mean particle size were calculated to be ~40 nm. SEM micrographs indicate that the particle sizes were observed in the nanometer range with dense microstructure, which leads to increase in the densification of the material. FT-IR result confirms the presence of metal bondings in the material. DTA peaks observed at 725°C and 880°C show the crystallization of the material and the corresponding weight loss was recorded in the TG spectrum. I-V & I-P results show that the maximum open cell voltage (OCV) was measured at 1.1V and the maximum power density of about 801mWcm2 was observed which may be due to the substitution of Gd ions into the BaCeYO3 sites showing an improved electrochemical performance of IT-SOFC electrolytes.
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Authors: Rui Li, Xiu Hua Chen, Wen Hui Ma, Jie Xing, Jian Jun Yang, Jie Yu
Abstract: Perovskite-structure La0.7Sr0.3Cr0.5Mn0.5O3-δanode powder was prepared by glycine nitrate process. The result of characterization indicated that the pore morphology and mechanical property of anode support pellets using starch as pore-forming agent are superior to that of using activated carbon. The maximum value of porosity and specific surface area are 40%, 1.256m2/mg at 10MPa, respectively. The conductive mechanism is small-polaron conductive mechanism at low temperature, but it is metalloid conductive mechanism at high temperature.
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