• 한국표면공학회지
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• 제30권5호
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• pp.333-346
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• 1997

Plasma spray processes for functional coatings of tubular SOFC ( Soild oxide Fuel Cell).consisting of air electrode, oxide electrolyte, an fuel electrode, are optimized by fully saturated fractional factorial testing. Material and electric characteristics of each coating are analtsed by the implementation of SEM and optical microscope for evaluating microstructure and porosity, X-ray diffraction method for investigating compositional change between raw powder and sprayed coating, and Van der Pauw method for measuring electrical conductivity. LSM ($La_{0.65}Sr_{0.35}MnO_3$air electrode and Ni-YSL fuel electrode coatings have porosities of around 23~30% sufficient for effective fuel and oxidant gas supply to electrochemical reaction interfaces and electrical conductivities of around 90 S/cm and 1000 S/cm, respectively, enough for acting as current collecting electrodes. YSZ($ZrO_2-8mol%Y_2O_3$) electrolyte film has a high ionic conductivities of 0.05~0.07 S/cm at $1000^{\circ}C$ in air atmosphere, but appears to be somewhat too porous to reduce the thickness. for enhancing the cell efficiency. A unit tubular SOFC has beem fabricated by the optimized plasma spray processes for each functional coating and the cell. Its electrochemical chracteristics are investigated by measuring voltage-current and power density with variation of operationg temperature, radio of fuel to air gas flowrates, and total gas flowrate of reactants.

• 한국재료학회지
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• 제11권5호
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• pp.339-344
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• 2001

코발트 산화물 박막을 전극으로 하여 Pt/Ti/Si 기판위에 Co$_3$O$_4$/LiPON/Co$_3$O$_4$로 구성된 전고상의 박막형 슈퍼캐패시터를 제작하였다. 각각의 Co$_3$O$_4$박막은 반응성 dc 마그네트론 스퍼터를 이용하여 $O_2$/[Ar+O$_2$] 비를 증가 시키며 성장시켰고, 비정질 LiPON 고체전해질 박막은 순수한 질소분위기 하에서 rf 스퍼터링으로 성장시켰다. 비록 벌크 타입의 슈퍼캐패시터에 비해 낮은 전기용량 (5-25mF/$\textrm{cm}^2$-$\mu\textrm{m}$)을 가졌지만, Co$_3$O$_4$/LiPON/Co$_3$O$_4$ 구조로 제작된 전고상 박막형 슈퍼캐패시터는 벌크 타입과 비슷한 거동을 나타내었다 0-2V의 전압구간, 50$\mu\textrm{A}/\textrm{cm}^2$의 전류밀도에서 약 400사이클 까지 안정한 방전용량을 유지함을 관찰할 수 있었다 이러한 전고상 박막형 슈퍼캐패시터의 전기화학적 특성은 $O_2$/[Ar+O$_2$] 비에 의존하는데, 이러한 의존성을 구조적, 전기적 특성 및 표면특성을 분석하여 설명하였다.

• 한국수소및신에너지학회논문집
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• 제7권1호
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• pp.29-37
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• 1996

Alkaline water electrolysis has been commercialized as the only large-scale method for a long time to produce hydrogen and the technology is superior to other methods such as photochemical, thermochemical water splitting, and thermal decomposition method in view of efficiency and related technical problem. However, such conventional electrolyzer do not have high electric efficiency and productivity to apply to large scale hydrogen production for energy or chemical feedstocks. Solid polymer electrolyte water electrolysis using a perfluorocation exchange membrane as an $H^+$ ion conductor is considered to be a promising method, because of capability for operating at high current densities and low cell voltages. So, this is a good technology for the storage of electricity generated by photovoltaic power plants, wind generators and other energy conversion systems. One of the most important R&D topics in electrolyser is how to minimize cell voltage and maximize current density in order to increase the productivity of the electrolyzer. A commercialized technology is the hot press method which the film type electrocatalyst is hot-pressed to soild polymer membrane in order to eliminate the contact resistance. Various technologies, electrocatalyst formed over Nafion membrane surface by means of nonelectrolytic plating process, porous sintered metal(titanium powder) or titanium mesh coated with electrocatalyst, have been studied for preparation of membrane-electrocatalyst composites. In this study some experiments have been conducted at a solid polymer electrolyte water electrolyzer, which consisted of single cell stack with an electrode area of $25cm^2$ in a unipolar arrangement using titanium mesh coated with electrocatalyst.

• 전기화학회지
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• 제13권3호
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• pp.186-192
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• 2010

흑연과 1-buthyl-2,3-dimethylimidazolium(BDMI)계 이온성 액체의 계면 반응을 이해하기 위하여 lithium bis(fluorosulfonyl)imide(LiTFSI)가 용해된 BDMI-TFSI 용액 중에서 전기화학 원자간력 현미경(electrochemical atomic force microscopy, ECAFM)을 이용하여 순환 전압전류법 전후에 있어서의 고배향성 열분해 흑연(highly oriented pyrolytic graphite, HOPG)의 표면을 in-situ로 관찰하였다. HOPG 전극에서 리튬의 가역적인 삽입과 탈리반응은 진행되지 않았으며, $BDMI^+$ 양이온의 삽입에 의한 blister의 형성 및 그라펜 층의 파괴만이 관찰되었다. 한편, $BDMI^+$ 양이온의 삽입 반응은 농도가 4.90 mol/kg인 LiTFSI-propylene carbonate(PC)를 15 wt% 함유하고 있는 BDMI-TFSI계에서는 일어나지 않았으며, 이 경우에는 가역적인 리튬의 삽입과 탈리반응이 진행 되었다. ECAFM 결과는 고농도의 PC계 용액이 solid electrolyte interface(SEI)를 형성함으로 인해 $BDMI^+$ 양이온의 삽입을 막는 매우 효과적인 첨가제임을 나타내었다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.237.2-237.2
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• 2013

ReRAM cell, also known as conductive bridging RAM (CBRAM), is a resistive switching memory based on non-volatile formation and dissolution of conductive filament in a solid electrolyte [1,2]. Especially, Chalcogenide-based ReRAM have become a promising candidate due to the simple structure, high density and low power operation than other types of ReRAM but the uniformity of switching parameter is undesirable. It is because diffusion of ions from anode to cathode in solid electrolyte layer is random [3]. That is to say, the formation of conductive filament is not go through the same paths in each switching cycle which is one of the major obstacles for performance improvement of ReRAM devices. Therefore, to control of nonuniform conductive filament formation is a key point to achieve a high performance ReRAM. In this paper, we demonstrated the enhanced repeatable bipolar resistive switching memory characteristics by spreading the Ag nanocrystals (Ag NCs) on amorphous GeSe layer compared to the conventional Ag/GeSe/Pt structure without Ag NCs. The Ag NCs and Ag top electrode act as a metal supply source of our devices. Excellent resistive switching memory characteristics were obtained and improvement of voltage distribution was achieved from the Al/Ag NCs/GeSe/Pt structure. At the same time, a stable DC endurance (>100 cycles) and an excellent data retention (>104 sec) properties was found from the Al/Ag NCs/GeSe/ Pt structured ReRAMs.

• 전기전자학회논문지
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• 제26권4호
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• pp.705-709
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• 2022

Poly(vinylidene fluoride-trifluoroethylene)(P(VDF-TrFE)) 고체 전해질 층의 어닐링 온도가 고분자 멤리스터의 전기적 특성에 미치는 영향을 분석하였다. 형태적 분석에서 100℃ 어닐링 온도를 갖는 P(VDF-TrFE) (100P(VDF-TrFE)) 박막 대비 200℃ 어닐링 온도를 갖는 P(VDF-TrFE) (200P(VDF-TrFE)) 박막의 표면 거칠기가 약 5배 크고 두께는 약 20% 작은 것으로 나타났다. 100P(VDF-TrFE)를 갖는 멤리스터 (M100) 대비 200P(VDF-TrFE) 멤리스터 (M200)의 set voltage는 약 50% 감소하였고, reset voltage의 크기는 약 30% 증가하였다. 또한, M200이 M100보다 더 나은 메모리 유지 특성을 갖는 것으로 나타났다. 이러한 차이는 M100 대비 M200 내부의 강한 국소 전기장 때문인 것으로 판단된다. 본 연구는 고분자 멤리스터의 어닐링 온도의 중요성을 제시함에 의의가 있다.

• 한국재료학회지
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• 제11권4호
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• pp.283-289
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• 2001

50/50 vol% LSM-YSZ (La$_{1-x}$Sr$_{x}$MnO$_3$-yttria stabilized zirconia)의 복합공기극이 콜로이드 증착법에 의해 연마된 YSZ 전해질상에 증착되었다. 그 전극 특성은 주사전자현미경, X선회절과 임피던스 분석기에 의해 연구되어졌다. 90$0^{\circ}C$에서 공기/LSM -YSZ/YSZ/Pt/공기 셀에 대해 측정된 전형적인 임피던스 스펙트럼들은 2개의 불완전한 호(depressed arc)로 구성되었다. LSM 전극에 대한 YSZ의 첨가는 전극내의 삼상계(TPB) 영역을 증가시켰으며, 이것이 LSM-YSZ 복합공기극의 비저항을 감소시켰다. 또한 전해질 표면의 불순물 제거와 TPB 길이의 증가를 위한 전해질 표면연마는 공기극의 비저항을 훨씬 더 감소시켰다. LSM-YSZ 공기극의 비저항은 작동온도, 공기극의 조성과 입자크기, 인가전류 및 전해질의 표면거칠기에 의해 큰 영향을 받았다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 Techno-Fair 및 추계학술대회 논문집 전기물성,응용부문
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• pp.123-124
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• 2008

In this study, we studied the nature of thin films formed by photodoping chalcogenide materials with for use in programmable metallization cell devices, a type of ReRAM. We investigated the resistance of Ag-doped chalcogenide thin films varied in the applied voltage bias direction from about $1M{\Omega}$ to several hundreds of ${\Omega}$. As a result of these resistance change effects, it was found that these effects agreed with PMC-RAM. The results imply that a Ag-rich phase separates owing to the reaction of Ag with free atoms from the chalcogenide materials.

• Journal of Electrochemical Science and Technology
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• 제11권1호
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• pp.41-49
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• 2020

In this study poly(carbazole) films deposited on stainless steel have been investigated as electrode material for supercapacitor applications. Poly(carbazole) films were electrodeposited using cyclic voltammetry in presence of lithium, sodium and tetrabutylammonium perchlorate salts. Poly(carbazole) films doped with perchlorate anions having different counter cations were characterized by SEM, ATR-FTIR and solid state conductivity measurements. Capacitive behaviours of PCz coated steel electrodes were tested by cyclic voltammetry, charge-discharge analysis and electrochemical impedance spectroscopy. It was found that counter cation of the dopant is significantly effective on the capacitive performance on the obtained PCz films and the PCz film synthesized from lithium perchlorate has the better capacitive performance than the poly(carbazole)s synthesized from sodium perchlorate and tetrabutylammonium perchlorate salts.

• 한국세라믹학회지
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• 제34권10호
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• pp.1067-1073
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• 1997

The yttria doped ceria (YDC) thin films were fabricated by electrochemical vapor deposition on the porous $\alpha$-Al2O3 substrate. The growth rates of the films obeyed a parabolic rate law, which constant was 259.0 $m^2$/hr at 120$0^{\circ}C$. As deposition temperature (above 110$0^{\circ}C$) increased, dense thin films were enhanced. Mole fraction of XYC13 had an effect upon surface morphologies. Electrical conductivity was increased with deposition temperature. The conductivity of YDC film prepared at XYC13=7.9$\times$10-2 was about 0.097 S/cm at 104$0^{\circ}C$ and the activation energy of conduction was calculated to be 26.6 kcal/mol.