Eiichi Yasumoto

Operating Properties of Solid Oxide Fuel Cells Using BaCe0.8Gd0.2 O 3 − α Electrolyte

The performance and the long-term operating properties of solid oxide fuel cells (SOFCs) using BaCeo 0.8 GdO 0.2 O 3-α (BCG) ceramics as the electrolyte have been investigated. A hydrogen-air fuel cell using BCG electrolyte with a thickness of 0.5 mm exhibited good performance at 800°C. Its short-circuit current was 0.9 A cm -2 , and there was hardly any degradation of BCG electrolyte in 1600 h of operation. When a quasi-fuel gas containing 8% CO 2 , which was expected by the reformation of the city gas (CH 4 ) at 800°C, was supplied to this cell, its short-circuit current was 0.63 A cm -2 and the cell worked stably under the discharge current density of 100 mA cm -2 for 2500 h. Some sintered metals (Fe, Co, Ni) were examined as a anode material for this electrolyte. Ni is a promising anode material for BCG electrolyte from the point of view of performance and durability.

Sensing Properties of an Oxygen Sensor Using BaCe0.8Gd0.2 O 3 − α Ceramics as Electrolytes

Limiting-current-type oxygen sensors using BaCe{sub 0.8}Gd{sub 0.2}O{sub 3{minus}{alpha}} (BCG) ceramics as electrolytes were constructed on a trial basis and their sensing properties investigated in order to develop a new oxygen sensor to replace the zirconia type. BCG ceramics exhibited high conductivity in the temperature range 200--1,000 C, and it was verified that the oxide ion could be a conductive carrier in BCG in oxygen at low temperatures (300 C). The oxygen sensors using BCGs worked at 300 C, and their output currents linearly increased with an increase in oxygen concentration in the range 1--22%. They could respond within 30 s between 1 and 21%, and humidity only slightly affected sensing performance. BCG seems to be a promising electrolyte material for an oxygen sensor operating at low temperatures (300 C).

Operating properties of solid oxide fuel cells using BaCe{sub 0.8}Gd{sub 0.2}O{sub 3{minus}{alpha}} electrolyte

The performance and the long-term operating properties of solid oxide fuel cells (SOFCs) using BaCeo 0.8 GdO 0.2 O 3-α (BCG) ceramics as the electrolyte have been investigated. A hydrogen-air fuel cell using BCG electrolyte with a thickness of 0.5 mm exhibited good performance at 800°C. Its short-circuit current was 0.9 A cm -2 , and there was hardly any degradation of BCG electrolyte in 1600 h of operation. When a quasi-fuel gas containing 8% CO 2 , which was expected by the reformation of the city gas (CH 4 ) at 800°C, was supplied to this cell, its short-circuit current was 0.63 A cm -2 and the cell worked stably under the discharge current density of 100 mA cm -2 for 2500 h. Some sintered metals (Fe, Co, Ni) were examined as a anode material for this electrolyte. Ni is a promising anode material for BCG electrolyte from the point of view of performance and durability.

The Exchange Current Density of Oxide Cathodes in Molten Carbonates

The exchange current density (i 0 ) for oxygen reduction has been measured by using a potential step technique on nonporous oxide electrodes in an Li/K(62/38 mole percent) carbonate eutectic melt at 923 K. Nonporous oxides were fabricated by a hot isostatic pressing method to be as dense as possible to study the kinetic parameters of the oxygen reduction on smooth oxide electrodes. However, the nonporous oxides had slightly rough surfaces. Accordingly, to allow for electrode roughness, the area of the nonporous oxide electrodes were corrected from the double-layer capacity values to make a comparison between our nonporous oxide electrodes and those used by other researchers

Particle growth behaviour of LiAlO2 containing ZrO2 in Li/Na carbonate electrolytes

Abstract The growth of particles of lithium aluminate (LiAlO 2 ) as an electrolyte retention material in molten carbonates leads to a decrease in the electrolyte retention ability, and so the performance of the fuel cell deteriorates. We have studied how to improve the material in order to maintain the electrolyte retention ability for a long term in Li/Na carbonates. As a result, we found that zirconia powder added to lithium aluminate keeps the electrolyte retention ability constant for over 7000 h in the alkaline carbonate in a P CO 2 =0.1 atmosphere.

Sensing properties of an oxygen sensor using BaCe{sub 0.8}Gd{sub 0.2}O{sub 3{minus}{alpha}} ceramics as electrolytes

Limiting-current-type oxygen sensors using BaCe{sub 0.8}Gd{sub 0.2}O{sub 3{minus}{alpha}} (BCG) ceramics as electrolytes were constructed on a trial basis and their sensing properties investigated in order to develop a new oxygen sensor to replace the zirconia type. BCG ceramics exhibited high conductivity in the temperature range 200--1,000 C, and it was verified that the oxide ion could be a conductive carrier in BCG in oxygen at low temperatures (300 C). The oxygen sensors using BCGs worked at 300 C, and their output currents linearly increased with an increase in oxygen concentration in the range 1--22%. They could respond within 30 s between 1 and 21%, and humidity only slightly affected sensing performance. BCG seems to be a promising electrolyte material for an oxygen sensor operating at low temperatures (300 C).