Entity

Time filter

Source Type


Tsushima S.,Tokyo Institute of Technology | Ikeda T.,Tokyo Institute of Technology | Koido T.,Honda Research and Development Co. | Hirai S.,Tokyo Institute of Technology
Journal of the Electrochemical Society | Year: 2010

An environmentally controlled magnetic resonance imaging (MRI) system was developed to investigate the effects of relative humidity (RH) and current density on the transverse water content profile in a membrane under fuel cell operation at a practical fuel cell (PEMFC) operating temperature. The MRI visualization revealed that in a dry condition (40% RH), the water content in the membrane (membrane hydration number, λ) was ∼3, and the water content profile was flat because the diffusion process in the membrane was dominant in the water transport. In a standard condition (80% RH), a water content of ∼8 in the membrane and partial dehydration at the anode were observed at a current density of 0.2 A/ cm2, indicating that electro-osmosis was influential. In a wet condition (92% RH), a higher water content of around λ=15 was observed than that at 80% RH, suggesting that the generated water in the cathode catalyst layer was transported to the membrane at 92% RH. A larger water concentration gradient was observed at 0.1 A/ cm2 with 92% RH than that at 80% RH, suggesting that the larger water content in the membrane induced a greater electro-osmotic drag as the electro-osmosis coefficient was positively correlated with the water content. © 2010 The Electrochemical Society. Source


Nakayama S.,Niihama National College of Technology | Higuchi Y.,Honda Research and Development Co. | Sugawara M.,Honda Research and Development Co. | Makiya A.,Nagaoka University of Technology | And 2 more authors.
Ceramics International | Year: 2014

The c-axis-oriented apatite-type lanthanum silicate, La10Si 6O27, ceramic was successfully fabricated by an application of a high magnetic field followed by a sintering process. Degree of an orientation in the La10Si6O27 ceramic sintered at 1700 C was 48.1% along (00l) on the Lotgering scale. Conductivity of the c-axis-oriented La10Si6O27 ceramic is about 0.5 orders of magnitude higher than that of the non-oriented La 10Si6O27 ceramic. The higher conductivity is caused by an orientation of oxide ions in the grains composing the ceramic, which are located along the c-axis and responsible for the ionic conduction. © 2013 Elsevier Ltd and Techna Group S.r.l. All rights reserved. Source


Nakayama S.,Niihama National College of Technology | Ikesue A.,World Laboratory Co. | Higuchi Y.,Honda Research and Development Co. | Sugawara M.,Honda Research and Development Co. | Sakamoto M.,Yamagata University
Journal of the European Ceramic Society | Year: 2013

A hexagonal apatite-type La 9.33Si 6O 26 single crystal as an oxide ionic conductor has been successfully prepared by a method which is based on the single crystallization of the sintered polycrystalline La 9.33Si 6O 26 ceramic on the surface of seed single crystal without their melt. The anisotropy in its conductivity was observed: conductivity component parallel to the c-axis was ca. 100 times higher than the perpendicular component. © 2012 Elsevier Ltd. Source


Higuchi Y.,Honda Research and Development Co. | Sugawara M.,Honda Research and Development Co. | Onishi K.,Niihama National College of Technology | Sakamoto M.,Yamagata University | Nakayama S.,Niihama National College of Technology
Ceramics International | Year: 2010

Electrical properties of LaxM6O12+1.5x (M = Si, Ge) as an electrolyte for solid oxide fuel cell (SOFC) have been investigated. In LaxSi6O12+1.5x and LaxGe6O12+1.5x of x = 8-11, the highest conductivities were achieved at x = 9.7 (La9.7Si6O26.55) and x = 9.0 (La9.0(GeO4)6O1.5), respectively. The conductivity of La9.0(GeO4)6O1.5 was higher than that of La9.7Si6O26.55 in a temperature region higher than 700 °C, and the conductivity (2.4 × 10-3 S cm-1) of La9.7Si6O26.55 at 400 °C was higher than that (8.3 × 10-5 S cm-1) of La9.0(GeO4)6O1.5. The power densities of SOFC (H2 | Pt | electrolyte (thickness: 1 mm) | Pt | O2) using La9.0(GeO4)6O1.5 as an electrolyte were 14.3 mW cm-2 (700 °C) and 24.0 mW cm-2 (800 °C). The corresponding SOFC using La9.7Si6O26.55 was found to work even at lower temperatures of 400 and 500 °C with power densities of 0.011 and 0.12 mW cm-2. The SOFC (H2 | Ni-Sm0.2Ce0.8O1.9 | electrolyte | Ba0.5Sr0.5Co0.8Fe0.2O2.5 | air) using 0.3 mm thickness La9.7Si6O26.55 electrolyte gave the 3.4 mW cm-2 power density at 500 °C. © 2009 Elsevier Ltd and Techna Group S.r.l. Source

Discover hidden collaborations