Papers by Keyword: Solid Oxide Fuel Cell (SOFC)

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Authors: Keisuke Tanaka, Yoshiaki Akiniwa, Hidehiko Kimura, Kenji Ukai, Misuzu Yokayama, Yasunobu Mizutani
Abstract: The internal stress in solid-oxide fuel cells (SOFCs) was evaluated during the thermal, reduction and re-oxidation cycles by using high-energy X-ray synchrotron radiation of about 70 keV at Beam line BL02B1 of SPring-8. The oxidized cell has a compression of about 400 MPa in the c-ScSZ electrolyte and a tension of 50-100 MPa in the NiO-YSZ anode at room temperature. In-situ measurement during the thermal cycle in an air atmosphere, the internal stress decreased with increasing temperature, becoming approximately zero at 1000 K. After the thermal cycle, the internal stress returned to its initial value. In the measurement during the reduction cycle, the internal stress was smaller than that measured during the cooling cycle after the anode was reduced from NiO-YSZ to Ni-YSZ. In the re-oxidation cycle of a reduced cell, the internal stress in the electrolyte went into tension above 800 K when the anode was re-oxidized from Ni-YSZ to NiO-YSZ. This tensile stress is responsible for possible fracture of unit cells in SOFCs.
Authors: Wei Hsin Tien, Shuang Shii Lian, Chia Ying Li, Wei Ja Shong, Ruey Yi Lee
Abstract: This paper presents the development of anode substrates of solid oxide fuel cells (SOFCs), prepared by rotating electrode powder-making equipment to improve the efficiency of cells and the coking issue that appears in traditional Ni-YSZ composite anodes when operated with hydrocarbon fuel. Combining the advantage of good electronic conductivity, leading less carbon residue of copper and high temperature oxidation resistance of Cr or Ni, the anode substrate is designed with Cu-Ni and Cu-Cr alloys so that the cells are able to work within the service temperature of 800-1000 C. To optimize the properties of conductivity, less carbon deposition and heat resistance, this research has invented substrates of copper-based dual metal composite alloys which are different from ordinary anode cermet powder made of nickel-ceramic composites. This new anode powder of dual metal alloys is made by rotating electrode powder-making equipment, with the powders being sintered to porous substrates. Experimental results show that the substrate has a good porosity and an electrical conductivity.
Authors: Qi Bing Chang, Xia Wang, Jian Er Zhou, Yong Qing Wang, Guang Yao Meng
Abstract: To explain the deformation during the co-sintering of NiO/YSZ-YSZ coating, the sintering shrinkage of NiO, NiO/YSZ and YSZ were measured by dilatometer. The coefficient of deformation variable (CDV, α) is defined to describe the difference of the sintering behaviors between the layers constrained.
Authors: Nir Ben-Oved, Olivera Kesler
Abstract: A new rapid manufacturing technique for the production of SOFC anodes for direct oxidation of hydrocarbon fuels has been demonstrated. Composite anodes with doped ceria as catalyst and ion conductor and copper as electronic conductor have been fabricated by plasma spraying in air. The process, which can be readily automated and scaled up for mass production, provides a rapid method to produce anodes with mixtures of low and high melting temperature components in several minutes. These anodes previously have required complex multi-step, multi-day processes involving infiltration of sintered pre-forms. This work demonstrates the feasibility of using plasma spray processing to manufacture composite Cu-SDC coatings for application in direct-oxidation SOFC anodes.
Authors: Massimiliano Lo Faro, Giuseppe Monforte, Alessandro Stassi, Maurizio Minutoli, Vincenzo Antonucci, Vincenza Modafferi, Pierluigi Antonucci, Antonino Salvatore Arico’
Abstract: A Ni-modified La0.6Sr0.4Fe0.8Co0.2O3 / Ce0.9Gd0.1O2 catalyst was prepared by incipient wetness. The product thus obtained was calcined at 1100°C for 2 h in static air. After thermal activation, Ni was mainly present as highly dispersed La2NiO4 on the surface of perovskite surface. The thermal reduction at 800 °C caused the occurrence of metallic Ni on the surface. Surface area was determined by BET measurement. The catalyst was used as anode in IT-SOFCs fed with methanol. Studies under steam reforming, partial oxidation and autothermal reforming of methanol were carried out at 800°C. A comparison was made between the performance of SOFCs fed with syngas or methanol. The results with methanol are promising both in terms of energy density as well as suitable performance for portable power sources.
Authors: Penyarat Saisirirat
Abstract: A micro scale model of a solid oxide fuel cell (SOFC) involving the mass transfer together with the electrochemical reaction, the electron and ion transports through respective cylindrical shaped electron-and ion-conducting particles inside the electrodes was mathematically developed. The predicted cell performance was showed according to the operating and design condition. The effects of micro-scale electrode geometry on the cell performance were also taken into account. This present study reveals the working mechanisms of SOFC at the micro-scale level, while demonstrating the use of micro-scale relations to enhance the SOFC performance. The accuracy of the presented model was validated by comparing to already existing experimental results from the available literatures.
Authors: Xin Ge Zhang, Cyrille Decès-Petit, Sing Yick, Mark Robertson, Wei Qu, Yong Song Xie, Rob Hui, Edward Styles, Justin Roller, Olivera Kesler, Radenka Maric, Dave Ghosh
Abstract: In this study, an addition of Co and Cu oxides to Sm0.2Ce0.8O1.9 (SDC) was studied to improve the SDC sinterability. It has been found that both Co and Cu oxide are very effective as sintering aids, and the SDC sintering temperature can be reduced from 1400°C without aids to below 1000°C with only 1at.% of either Cu or Co. As compared to the pure SDC, a slight decrease of ionic conductivity was observed in SDC with Cu sintering aid. There is no obvious effect on electrochemical property of SDC with Co sintering aid under 2.5at.%.
Authors: Florence Ansart, Jean Pierre Bonino, P. Lenormand, Ch. Robert, Céline Viazzi
Authors: Iman Azarian Borojeni, Babak Raissi, Amir Maghsoudipour, Mahmood Kazemzad, Ehsan Marzbanrad
Abstract: In this research aging behaviors of yttria stabilized zirconia (YSZ) in non aqueous suspensions, namely ethanol, isopropanol, n-propanol, acetylacetone and the mixture of ethanol-acetylacetone were investigated. For this purpose, electrical conductivity, electrophoretic mobility and suspension stability during aging time (6 to 7 days) were evaluated. Except for the ethanol-acetyl acetone mixture, each suspension contained 0 to 0.8 g/L iodine. It was revealed that, the alcoholic suspensions indicated lower conductivity in comparison with acetylacetone suspensions. However, acetylacetone suspension showed lower conductivity variation with time. Although iodine could improve the electrophoretic mobility of ethanol and acetylacetone suspensions, it had little effect on electrophoretic mobility of isopropanol and n-propanol suspensions. Also, it was indicated that iodine as a dispersant was not helpful for alcoholic suspensions stability. It was concluded that the mixture of acetylacetone-ethanol suspension was the best candidate in this study for electrophoretic deposition of YSZ, owing to its little behavior variation with the aging time, low conductivity and high electrophoretic mobility. High quality crack-free layers were electrophoretically deposited from this suspension on the substrate by applying 50 V/cm electrical field.
Authors: B.D. White, Olivera Kesler
Abstract: Porous composite cathodes containing (La0.8Sr0.2)0.98MnO3 (LSM) and yttria stabilized zirconia (YSZ) for use in solid oxide fuel cells (SOFCs) have been produced by air plasma spraying. Deposition was carried out using axial powder injection for increased deposition efficiency and composition control. A number of composite cathodes were produced using different combinations of parameter values within the identified range. Successful coatings were then characterized for composition and porosity using EDX and SEM. As a result of these tests, combinations of input parameter values were identified that are best suited to the production of coatings with microstructures appropriate for use in SOFC composite cathodes.
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