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Sanghoon Ji,WeonJae Kim,Sangjong Han,Seokhun Jeong,Taehyun Park 한국정밀공학회 2023 International Journal of Precision Engineering and Vol.10 No.4
The dry reformate and wet reformate operations of solid oxide fuel cell (SOFC) with 200 nm-thick, nanoporous Ni thin-film anode were investigated in terms of power performance at 500°C. The initial power density of the SOFC fueled with dry reformate (H2 75%, CO 10%, CO2 10%, CH4 5%) was 5% lower than that of the SOFC fueled with H2, which was almost similar to that of the SOFC fueled with wet reformate humidified by water bubbling at room temperature. The reduction rate in power density of the SOFC fueled with the dry reformate was as high as 6%/hr; the reduction rate in power density of the SOFC fueled with the wet reformate was decreased by 55% through carbon poisoning alleviation of the Ni thin-film anode.
Sanghoon Ji 한국정밀공학회 2020 International Journal of Precision Engineering and Vol.21 No.6
The thickness of an ultrathin blocking layer for anodic aluminum oxide (AAO)-supported thin-fi lm solid oxide fuel cells is determined. The atomic layer-deposited (ALD) ultrathin yttria-stabilized zirconia (YSZ) blocking layer for gadolinia-doped ceria (GDC) electrolyte cell is deposited on 300 nm-thick Pt anode-coated AAO substrates. The surface of AAO substrates is examined to be non-uniform in terms of pore size and bump inclination by fi eld emission scanning electron microscopic analysis. While the average pore size is 130 nm, the pore size ranges from 36 to 207 nm. While the average slope angle is 42°, the slope angle ranges from 9° to 79°. A growth modelling result considering the pore sizes and the slope angles presents that highly reliable ALD-deposited YSZ blocking layers need to be thicker than 93 nm. This prediction well corresponds to the evolution of open circuit voltages for 400 nm-thick GDC electrolyte cells with 60 nm-thick and 120 nm-thick ALDdeposited YSZ blocking layers.
Sanghoon Ji,Jihwan An,Dong Young Jang,Youngseok Jee,Joon Hyung Shim,Suk Won Cha 한국물리학회 2016 Current Applied Physics Vol.16 No.3
The electrical conductivity of ~200 nm-thick gadolinium-doped ceria (GDC) thin films deposited at various substrate temperatures by radio-frequency sputtering was evaluated in a temperature range of 400 Ce550 C as an electrolyte for solid oxide fuel cells operated at low temperatures. Morphological, chemical, and crystalline properties were discussed to determine the electrical conductivity; in particular, the electrical conductivity of GDC thin film deposited at 300 C was appreciably lower than that of GDC thin film deposited at 150 C. The columnar grain boundaries and the reduced ceria formed during the sputtering process are considered as the major factors leading to the measured results.
Ji, Sanghoon,Cho, Gu Young,Yu, Wonjong,Su, Pei-Chen,Lee, Min Hwan,Cha, Suk Won American Chemical Society 2015 ACS APPLIED MATERIALS & INTERFACES Vol.7 No.5
<P>Nanoscale yttria-stabilized zirconia (YSZ) electrolyte film was deposited by plasma-enhanced atomic layer deposition (PEALD) on a porous anodic aluminum oxide supporting substrate for solid oxide fuel cells. The minimum thickness of PEALD-YSZ electrolyte required for a consistently high open circuit voltage of 1.17 V at 500 °C is 70 nm, which is much thinner than the reported thickness of 180 nm using nonplasmatic ALD and is also the thinnest attainable value reported in the literatures on a porous supporting substrate. By further reducing the electrolyte thickness, the grain size reduction resulted in high surface grain boundary density at the cathode/electrolyte interface.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2015/aamick.2015.7.issue-5/am508710s/production/images/medium/am-2014-08710s_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/am508710s'>ACS Electronic Supporting Info</A></P>
수소극 Dead-End 모드 고분자 전해질 연료전지의 실험적 연구
지상훈(Sanghoon Ji),황용신(Yong-Sheen Hwang),최종원(Jong Won Choi),이대영(Dae-Young Lee),박준호(Joonho Park),장재혁(Jae Hyuk Jang),김민수(Min Soo Kim),차석원(Suk Won Cha) 대한기계학회 2010 大韓機械學會論文集B Vol.34 No.6
출구부가 폐쇄된 데드앤드 모드 운전은 연료이용률이 높고, 부가장치 소모동력이 작기 때문에 소형 연료전지 분야에 널리 적용되고 있다. 하지만 수증기나 질소 등과 같은 불순물의 축적으로 인해 성능이 저하되는 단점을 가지고 있다. 본 논문에서는 이러한 성능 저하의 요인 중 수분 축적의 영향을 알아보기 위해 부하 방식에 따른 거동, 퍼징 전후 분극 성능, 수분 축적 분포, 공기극 상대습도에 따른 성능을 알아보았다. 본 실험에 적용된 운전 조건에서의 성능 거동은 정전압 부하(0.4V)보다 정전류밀도 (600㎃/㎠)부하에서 보다 안정적으로 나타났다. 가시화 창을 통해 수소극에 축적된 대부분의 수분은 출구부에 가까운 부분에 분포함을 알 수 있었다. 또한 공기극 상대습도(0.15, 0.4, 0.75 RH)가 높아질수록 성능 유지 시간은 감소한 반면 성능 감소율은 증가하였다. 특히, 상대습도 0.15 에서의 성능 기준으로 평균출력밀도는 51% 증가하였고, 평균성능유지시간은 25% 감소하였다. Portable fuel cells are commonly operated in the dead-end mode because of such as high fuel utilization. However, the performance of such systems deteriorates continuously with an increase in the amount of by-products such as water vapor and nitrogen. In this study, to verify the effect of water vapor on Proton Exchange Membrane Fuel Cells (PEMFCs), constantload experiments were carried out for a current density of 600 ㎃/㎠ and a voltage of 0.4 V, respectively. The performance of the cell was more stable under constant voltage conditions than under constant current density conditions. Condensed water accumulated in the anode channel near the cell outlet. The experimental results show how the relative humidity (RH = 0.15, 0.4 and 0.75) of air at the cathode side affect the performance of PEMFCs with dead-end anode. At RH values higher than 0.15, the mean power density increased by up to 51% and the mean purge duration decreased by up to 25% compared to the corresponding initial values.
해외 수소에너지 저명학회를 통해 살펴본 연료전지 혁신기술
지상훈(Sanghoon Ji) 대한기계학회 2019 대한기계학회 논문집. Transactions of the KSME. C, 산업기술과 혁신 Vol.7 No.1
본 논문에서는, 수소에너지의 전 과정을 전반적으로 논의하는, Fuel Cell Seminar & Energy Exposition 2017에서 발표된 연료전지 관련 혁신기술들을 검토한다. 검토 분야는 연료 전처리, 재료 가공, 부품 생산/연결, 시스템 설계, 작동 제어로 나눠진다. 검토된 혁신기술들의 주요 내용은 다음과 같다. 1) 수동 흡착 시스템은 탈황 공정의 복잡성을 대폭 낮추어준다. 2) 단열 연화 과정을 통한 고속 성형은 금속 분리판의 생산 비용을 대폭 낮추어준다. 3) 기능성 재료를 이용한 코팅은 금속 분리판의 내구성 이슈를 해결해준다. 4) 저 응력 기밀제를 사용하는 것은 고온 연료전지와의 양립성을 증대시켜준다. 5) 가역 연료전지 시스템은 연료전지/전기분해 시스템의 구성을 간소화한다. 6) 주기적인 전류차단은 직접 탄화수소 공급형 저온 연료전지의 지속적 작동을 가능하게 한다. In this paper, we review the fuel cell innovative technologies announced at Fuel Cell Seminar & Energy Exposition 2017, where the whole process of hydrogen energy is discussed. Reviewing area is listed as follows: fuel pre-treatment, material processing, component production/connection, system design, and operation control. The main contents of reviewed innovative technologies are as follows. 1) Passive sorbent systems provide a simple solution for desulfurization. 2) High velocity forming through adiabatic softening cuts manufacturing cost of metal bipolar plates. 3) Coating using functional materials solves the durability issue of metals bipolar plates. 4) Using low sealing stress compression gasket enhances compatibility with high-temperature fuel cells. 5) Regenerative fuel cell system simplifies the configuration of fuel cell and electrolysis systems. 6) Periodic current interruption enables the sustainable operation of direct hydrocarbon-fueled low-temperature fuel cells.