Hyun Jun Ko
Yonsei University
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Publication
Featured researches published by Hyun Jun Ko.
Journal of The Korean Ceramic Society | 2010
Hyun Jun Ko; Jong Jin Lee; Sang-Hoon Hyun
It has been considered to apply GDC (Gd 0.1 Ce 0.9 O 1-X ) for low-temperature SOFC electrolytes because it has higher ionic conductivity than YSZ at low temperature. However, open circuit voltage with using GDC (Gd 0.1 Ce 0.9 O 1-X ) electrolyte in SOFCs, becomes lower than using YSZ (8 ㏖% Yttria stabilized Zirconia) electrolyte because GDC has electronic conductivity. In this work, the effect of changing GDC electrolyte thickness on the open circuit voltage has been investigated. Ni-GDC anode-supported unit cells were fabricated as follows. Mixed NiO-GDC powders were pressed and pre-sintered at 1200℃. And then, GDC electrolyte material was dip-coated on the anode and sintered at 1400℃. Finally the LSCF-GDC cathode material was screen-printed on the electrolyte and sintered at 1000℃. Electrolyte thickness was controlled by the number of dip-coating times. Open circuit voltage was measured depending on electrolyte thickness at 650℃ and found that the thicker GDC electrolyte was, the better OCV was.
Electrochemical and Solid State Letters | 2010
Hyun Jun Ko; Jong-Jin Lee; Sang-Hoon Hyun
It has been considered to apply Od 0.1 Ce 0.9 0 1―x (GDC) to low temperature solid oxide fuel cell (SOFC) electrolytes at a low temperature. However, ceria cannot be efficiently used with hydrogen and wet hydrocarbon fuels because its structure change Ce4 + → Ce 3+ ) causes a decline of mechanical strength under a reducing atmosphere. In this work, the structural stability test of the GDC electrolyte was investigated under H 2 and dry CH 4 atmospheres depending on the fuels at 650°C. This study clearly confirmed from the scanning electron microscopy, X-ray photoelectron spectroscopy, and mechanical strength data that many more Ce 4+ ions transform into Ce 3+ ions under the reducing (H 2 ) atmosphere [J. Alloys Compd., 408―412, 628 (2006); Solid State Sci., 7, 539 (2005)].
International Journal of Hydrogen Energy | 2012
Jae-ha Myung; Hyun Jun Ko; Hae-Gu Park; Moon Hwan; Sang-Hoon Hyun
International Journal of Hydrogen Energy | 2012
Hyun Jun Ko; Jae-ha Myung; Ji-Hwan Lee; Sang-Hoon Hyun; Jong Shik Chung
International Journal of Hydrogen Energy | 2014
Jae Ha Myung; Hyun Jun Ko; Chang Hyeok Im; Jooho Moon; Sang Hoon Hyun
Journal of Applied Electrochemistry | 2012
Hyun Jun Ko; Jae-ha Myung; Sang-Hoon Hyun; Jong Shik Chung
Archive | 2011
Jae-ha Myung; Hyun Jun Ko; Jong-Jin Lee; Sang-Hoon Hyun
216th ECS Meeting | 2009
Jong Jin Lee; Jae-ha Myung; Hyun Jun Ko; Sang-Hoon Hyun
Archive | 2012
Hyun Jun Ko; Jae-ha Myung; Ji-Hwan Lee; Sang-Hoon Hyun; Jong Shik Chung
Meeting Abstracts | 2012
Jae-ha Myung; Hyun Jun Ko; Ji-Hwan Lee; Sang-Hoon Hyun