The Experts below are selected from a list of 1386 Experts worldwide ranked by ideXlab platform
Koichi Eguchi - One of the best experts on this subject based on the ideXlab platform.
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influence of la sr mno3 δ cathode composition on cathode electrolyte interfacial structure during long term operation of solid oxide fuel cells
Journal of Power Sources, 2013Co-Authors: Toshiaki Matsui, Hiroki Muroyama, Yuichi Mikami, Koichi EguchiAbstract:Abstract Time-dependent events during operation of SOFCs, i.e., performance enhancement and/or deterioration, can be readily observed for the cell composed of strontium-doped Lanthanum Manganite (LSM) cathode and yttria-stabilized zirconia (YSZ) electrolyte, concomitant with the change in interfacial structure of LSM/YSZ. The influence of LSM composition on the electrochemical properties and microstructure of LSM/YSZ interface during prolonged operation was investigated. Four different LSM cathodes were used and the change in microstructure, especially TPB-length, was evaluated quantitatively by a focused ion beam–scanning electron microscope (FIB–SEM). For LSM cathodes with A-site deficient compositions, the change in TPB-length had a minor contribution to the performance enhancement after 20 h of galvanostatic operation. On the other hand, for 100 h duration an increase in cathode overpotential was confirmed, accompanied with the formation of thin layer of LSM over YSZ electrolyte. A series of phenomena were triggered by the change in oxygen nonstoichiometry of LSM under polarized states. The mechanism for microstructural change was proposed and the long-term stability of LSM/YSZ interface was discussed.
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simulation of dynamic response of strontium doped Lanthanum Manganite under cathodic polarization
Journal of The Electrochemical Society, 2010Co-Authors: Jun Yang, Toshiaki Matsui, Hiroki Muroyama, Koichi EguchiAbstract:A numerical model was proposed to simulate the electrochemical behavior of strontium-doped Lanthanum Manganite (LSM) under cathodic polarization by assuming the transient variation of oxygen concentration and the defect chemistry of LSM. From the simulation, it was revealed that the dynamic response of cathodic potential proceeded in two steps with different time domains. A drastic change in cathodic potential occurred soon after the current loading. In addition, the oxygen nonstoichiometry in LSM changed simultaneously, resulting in an enhancement in the electrochemical performance of the LSM cathode. The simulated phenomenon was validated by experimental results.
S H Chan - One of the best experts on this subject based on the ideXlab platform.
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electrochemical behavior of la sr mno3 electrode under cathodic and anodic polarization
Solid State Ionics, 2004Co-Authors: X J Chen, K A Khor, S H ChanAbstract:Abstract Electrochemical behavior of the strontium doped Lanthanum Manganite (LSM) electrode under cathodic and anodic current treatment was investigated by a.c. impedance spectroscopy and cyclic voltammetry. The reversible behavior of the LSM electrode may be related to the partial reduction and oxidation of the Mn ions under cathodic and anodic polarization. The performance of the LSM electrode was found to depend on the oxygen vacancies at the LSM surface, which would promote the transport of oxygen intermediate species at LSM surface close to the three-phase boundary (TPB) region. Results show that the impedance resistance of LSM electrode reduces with the increase of cathodic DC bias. The exponential dependence of Q H and Q L on the cathodic overpotential suggests that the reaction processes associated with the high- and low-frequency arcs to be chemical or physical processes.
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identification of o2 reduction processes at yttria stabilized zirconia doped Lanthanum Manganite interface
Journal of Power Sources, 2003Co-Authors: Xinbing Chen, K A Khor, S H ChanAbstract:Abstract Oxygen reduction processes at a yttria stabilized zirconia|doped Lanthanum Manganite (LSM|YSZ) interface are investigated by ac impedance spectroscopy. Three semi-arcs are clearly observed at an oxygen partial pressure ( p O 2 ) of 0.001 atm. The constant-phase element of frequency arc and the p O 2 -dependence of 1/ R ( R : resistance) are correlated to interpret the reaction processes associated with the frequency arcs. It is found that at least five elementary steps are involved in oxygen reduction at the LSM|YSZ interface. Three of these steps are identified as the rate-determining steps, namely: (i) gas diffusion through the porous LSM electrode from the bulk to the reaction sites; (ii) surface diffusion of oxygen intermediate species along the LSM surface; (iii) incorporation of oxygen ions from the three phase boundary into the YSZ electrolyte lattice. The p O 2 -dependent exchange current density of the rate-determining step predicted by model is consistent with the experimental data, which further confirms the validity of the proposed oxygen reduction processes at the LSM|YSZ interface.
Yuefeng Song - One of the best experts on this subject based on the ideXlab platform.
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improving the performance of solid oxide electrolysis cell with gold nanoparticles modified lsm ysz anode
Journal of Energy Chemistry, 2019Co-Authors: Yuefeng Song, Xiaomin Zhang, Yingjie Zhou, Houfu Lv, Weicheng Feng, Guoxiong WangAbstract:Abstract Gold, as the common current collector in solid oxide electrolysis cell (SOEC), is traditionally considered to be inert for oxygen evolution reaction at the anode of SOEC. Herein, gold nanoparticles were loaded onto conventional strontium doped Lanthanum Manganite-yttria stabilized zirconia (LSM-YSZ) anode, which evidently improved the performance of oxygen evolution reaction at 800 °C. The current densities at 1.2 V and 1.4 V increased by 60.0% and 46.9%, respectively, after loading gold nanoparticles onto the LSM-YSZ anode. Physicochemical characterizations and electrochemical measurements suggested that the improved SOEC performance was attributed to the accelerated electron transfer of elementary process in anodic polarization reaction and the newly generated triple phase boundaries in gold nanoparticles-loaded LSM-YSZ anode.
M A Garcia - One of the best experts on this subject based on the ideXlab platform.
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preparation thermal and phase evolution and functional properties of non stoichiometric strontium doped Lanthanum Manganite perovskite ceramics
Journal of The European Ceramic Society, 2017Co-Authors: M T Colomer, Angel L Ortiz, Victor Lopezdominguez, Jose M Alonso, M A GarciaAbstract:Abstract Powders of (La 0.85 Sr 0.15 ) 0.98 MnO 3-δ (LSM85) and (La 0.80 Sr 0.20 ) 0.98 MnO 3-δ (LSM80) perovskites have been synthesized and characterized in detail, and then sintered to evaluate their electrical and magnetic properties at low temperatures and at near room temperature. Microstructural observations/analyses after the dilatometric essays show that the perovskites have compositions that deviate from the nominal ones. Furthermore, magnetic characterization of both samples reveals a ferromagnetic behavior with a Curie temperature above 300 K for LSM80 and of 260 K for LSM85. In addition, LSM85 is insulator from 15 up to 300 K, whereas LSM80 is metallic up to 160 K and insulator up to 300 K. This significant discrepancy of behaviour is attributable to structural and compositional differences between the two perovskites.
Jooho Moon - One of the best experts on this subject based on the ideXlab platform.
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effect of starting particulate materials on microstructure and cathodic performance of nanoporous lsm ysz composite cathodes
Journal of Power Sources, 2007Co-Authors: Hwa Seob Song, Sanghoon Hyun, Jooho MoonAbstract:Abstract Nano-scale LSM–YSZ composite electrodes are prepared from a mixture of yttria stabilized zirconia (YSZ) and strontium-doped Lanthanum Manganite (LSM) particles. Commercial YSZ particles are mixed with polymerizable complex method-driven LSM powders of two different particle sizes, namely, 81 and 210 nm. Then, the correlations between the properties of the starting particles, sintering temperature, microstructure and cell performance are studied. Use of smaller LSM particles in the composite electrode induces extensive grain growth. This significantly reduces the triple phase boundary (TPB) and leads to an increase in the polarization resistance. The composite cathode derived from larger LSM particles exhibits a lower total polarization resistance (∼0.31 Ω cm 2 at 800 °C) and, subsequently, better maximum cell power (∼630 mA cm −2 ). By contrast, larger resistance and lower cell power are observed for electrodes composed of smaller LSM particles.
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fabrication and characterization of anode supported electrolyte thin films for intermediate temperature solid oxide fuel cells
Journal of Power Sources, 2005Co-Authors: Sanghoon Hyun, Jooho Moon, Rakhyun SongAbstract:Abstract Anode-supported electrolyte thin films for improving the solid oxide fuel cell (SOFC) performance at intermediate temperature (IT) have been manufactured by a wet-chemical process, and their microstructures, gas permeabilities, and electrical performances have been investigated. NiO–YSZ anode supports of a flat tube type were prepared by the extrusion method, and their surfaces were modified via slurry coating of fine NiO–YSZ particles for controlling the surface roughness and the pore size. An anode-supported yttria-stabilized zirconia (YSZ) electrolyte was fabricated by dip-coating YSZ slurry (viscosity 4.5 cP, solid contents 2.7 vol.%) onto the modified anode support, then it was coated with YSZ sol (viscosity 2.5 cP), and sintered at 1400 °C. The cathode consisted of three consecutive layers of LSM–YSZ composite, strontium-doped Lanthanum Manganite (LSM), and La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF). After each successive slurry layer was applied it was co-fired at 1200 °C. The thickness of YSZ electrolyte layers could be controlled below 15 μm, and the YSZ layers’ acceptability as an electrolyte film for an SOFC was estimated from the result of the gas impermeability ranging below 2 bar. The unit cells fabricated in this work showed a good electrical performance of 550 mW cm−2 at 850 °C. This is attributed to the reduced resistance through the thin YSZ electrolyte.
