• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 춘계학술대회 논문집
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• pp.299-302
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• 2009

Oxygen ionic conductors of YSZ electrolyte in SOFC unit cell are applied to anode and cathode as well as electrolyte to have triple-phase-boundaries(TPB) of electrochemical reaction, and it is required to decrease the sintering temperature of anode-supported electrolyte by the nanoscale of YSZ powder.In this report, nanoscale YSZ powder was synthesized by the chemical co-precipitation method. The particle size, surface area and morphology of the powder were observed by SEM and BET. Thin film electrolyte of under 10㎛ was fabricated by tape casting using the synthesized YSZ powder, and ionic conductivity and gas permiability of electrolyte film were evaluated. Finally, the SOFC unit cell was fabricated using the anode-supported electrolyte prepared by a tape casting method and co-sintering. Electrochemical evauations of the SOFC unit cell, including measurements such as power density and impedance, were performed and analyzed.

• Bulletin of the Korean Chemical Society
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• 제30권4호
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• pp.783-786
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• 2009

Thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and ion chromatography(IC) were employed to analyze the thermal behavior of $Li_xCoO_2$ cathode material of lithium ion battery. The mass loss peaks appearing between 60 and 125 ${^{\circ}C}$ in TGA and the exothermic peaks with 4.9 and 7.0 J/g in DSC around 75 and 85 ${^{\circ}C}$ for the $Li_xCoO_2$ cathodes of 4.20 and 4.35 V cells are explained based on disruption of solid electrolyte interphase (SEI) film. Low temperature induced HF formation through weak interaction between organic electrolyte and LiF is supposed to cause carbonate film disruption reaction, $Li_2CO_3\;+\;2HF{\rightarrow}\;2LiF\;+\;CO_2\;+\;H_2O$. The different spectral DSC/TGA pattern for the cathode of 4.5 V cell has also been explained. Presence of ionic carbonate in the cathode has been identified by ion chromatography and LiF reported by early researchers has been used for explaining the film SEI disruption process. The absence of mass loss peak for the cathode washed with dimethyl carbonate (DMC) implies ionic nature of the film. The thermal behavior above 150 ${^{\circ}C}$ has also been analyzed and presented.

• 한국세라믹학회지
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• 제43권12호
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• pp.751-757
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• 2006

Recently, a new type of solid oxide fuel cells has been developed employing extremely thin oxide electrolyte. These fuel cells are expected to operate at significantly reduced temperature compared to conventional solid oxide fuel cells. Accordingly, they may resolve the stability and material selection issues of high temperature fuel cells. Furthermore, they may eliminate the limitations of polymer membrane fuel cells whose operation temperature is under $100^{\circ}C$. In this paper, we review the electrolytes for intermediate temperature operation. Then, we discuss the current development of thin film solid oxide fuel cells that possibly operated at low temperatures.

• 한국재료학회지
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• 제31권11호
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• pp.614-618
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• 2021

As the size of market for electric vehicles and energy storage systems grows, the demand for lithium-ion batteries (LIBs) is increasing. Currently, commercial LIBs are fabricated with liquid electrolytes, which have some safety issues such as low chemical stability, which can cause ignition of fire. As a substitute for liquid electrolytes, solid electrolytes are now being extensively studied. However, solid electrolytes have disadvantages of low ionic conductivity and high resistance at interface between electrode and electrolyte. In this study, Li₇La₃Zr₂O₁₂ (LLZO), one of the best ion conducting materials among oxide based solid electrolytes, is fabricated through RF-sputtering and various electrochemical properties are analyzed. Moreover, the electrochemical properties of LLZO are found to significantly improve with co-sputtered Li₂O. An all-solid thin film battery is fabricated by introducing a thin film solid electrolyte and an Li₄Ti₅O₁₂ (LTO) cathode; resulting electrochemical properties are also analyzed. The LLZO/Li₂O (60W) sample shows a very good performance in ionic conductivity of 7.3×10^-8 S/cm, with improvement in c-rate and stable cycle performance.

• 한국수소및신에너지학회논문집
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• 제17권2호
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• pp.204-211
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• 2006

The electrolyte in the solid oxide fuel cell must be dense enough to avoid gas leakage and thin enough to reduce the ohmic resistance. In order to manufacture the thin and dense electrolyte layer, 8 mol% $Y_2O_3$ stabilized-$ZrO_2$ (8YSZ) electrolyte layers were coated on the porous tubular substrate by the novel vacuum slurry dip-coating process. The effects of the slurry concentration, presintering temperature, and vacuum pressure on the thickness and the gas permeability of the coated electrolyte layers have been examined in the vacuum slurry coating process. The vacuum-coated electrolyte layers showed very low gas permeabilities and had thin thicknesses. The single cell with the vacuum-coated electrolyte layer indicated a good performance of $495\;mW/cm^2$, 0.7 V at $700^{\circ}C$. The experimental results show that the vacuum dip-coating process is an effective method to fabricate dense thin film on the porous tubular substrate.

• 한국분말재료학회지
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• 제23권5호
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• pp.379-383
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• 2016

A thick film of $Li_7La_3Zr_2O_{12}$ (LLZO) solid-state electrolyte is fabricated using the tape casting process and is compared to a bulk specimen in terms of the density, microstructure, and ion conductivity. The final thickness of LLZO film after sintering is $240{\mu}m$ which is stacked up with four sheets of LLZO green films including polymeric binders. The relative density of the LLZO film is 83%, which is almost the same as that of the bulk specimen. The ion conductivity of a LLZO thick film is $2.81{\times}10^{-4}S/cm$, which is also similar to that of the bulk specimen, $2.54{\times}10^{-4}S/cm$. However, the microstructure shows a large difference in the grain size between the thick film and the bulk specimen. Although the grain boundary area is different between the thick film and the bulk specimen, the fact that both the ion conductivities are very similar means that no secondary phase exists at the grain boundary, which is thought to originate from nonstoichiometry or contamination.

• 한국세라믹학회지
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• 제41권8호
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• pp.593-598
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• 2004

1 $\mu$m이하의 전고상 리튬 박막전지의 구현을 위해 펄스 레이저 증착법을 이용하여 Pt/TiO$_2$/SiO$_2$/Si 기판위에 LiCoO$_2$정극을 증착온도와 Li/Co 간의 몰 비율을 변화시켜가며 성장시켰다. 특히, Li/Co=1.2의 조성을 갖는 LiCoO$_2$를 50$0^{\circ}C$의 증착온도에서 성장시킬 경우 53 $\mu$Ah/$cm^2$-$\mu$m의 높은 초기 용량값을 가지며 100 싸이클 후에도 67.6%의 용량값을 유지하였다. LiCoO$_2$/Pt/TiO$_2$/SiO$_2$/Si위에 고체 전해질인 (Li, La)TiO$_3$를 비정질상으로 하여 PLD방법으로 낮은 온도대역에서 증착온도를 다양하게 하여 증착하였다. 10$0^{\circ}C$의 증착온도에서 LiCoO$_2$Pt/TiO$_2$/SiO$_2$/Si위에 성장시킨 (Li, La)TiO를 가지고 LiClO$_4$ in PC 안에서 Li anode와 충$.$방전 측정 결과 약 51$\mu$Ah/$cm^2$-$\mu$m의 초기 용량값을 나타내었으며 100싸이클 후에도 90%의 훌륭한 방전용량의 보존력을 나타내었다. 비정질상의 (Li, La)TiO$_3$ 고체 전해질은 전고상 박막전지로의 구현이 가능하다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 추계학술대회 논문집
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• pp.164-164
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• 2007

Photodiffusion of silver into chalcogenide thin film is one of the most interesting effects that occurs in chalcogenide glass as it theatrically changes the properties of the initial material and forms a ternary. Programmable Metallization Cell(PMC) Randon Access Memory use for photodiffusion of mobile metal is based on the electrochemical growth and removal of nanoscale metallic pathway in thin film of solid electrolyte. This paper investigates the annling properties on Ag-doped $Ge_{25}Se_{75}$ thin film structure and describes the electrical characteristics of PMC-RAM. The composition of the intercalation products containing Ag is confirmed using X-ray diffraction which shows the formation of Ag-doped $Ge_{25}Se_{75}$.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 추계학술대회 초록집
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• pp.84.2-84.2
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• 2011

In this research, two thin film deposition techniques, Atomic Layer Deposition and Sputtering are carried out for the fabrication of Yittria Stabilized Zirconia electrolyte for thin film Solid Oxide Fuel Cell. Zirconium to Yittrium ratio for both cases is about 1/8. Scanning Electron Microscope(SEM) image shows that the growth rate per hour for Atomic Layer Deposition is faster than for sputtering. X-ray Photo-electron Spectroscopy(XPS) shows that the peaks of both Zirconia and Yittria shift towards higher bending energy for the case of Atomic Layer deposition and thus are more strongly attached to the substrate. Later, Nyquist plot was used to compare the conductivity of Yittria Stabilized Electrolyte for both cases. The conductivity at $300^{\circ}C$ for Atomic Layer Deposited Yittria Stabilized Zirconia is found to be $5{\times}10^{-4}S/cm$ while that for sputtered Yittria Stabilized Zirconia is $2{\times}10^{-5}S/cm$ at the same temperature. The reason for better performance for Atomic Layered YSZ is believed to be the Nano-structured layer fabrication that aids in along the plane conduction as compared to the columnarly structured Sputtered YSZ.

• 마이크로전자및패키징학회지
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• 제23권3호
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• pp.31-35
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• 2016

본 논문은 원자층 증착법을 이용해 증착된 YSZ 박막을 산화 세륨계 전해질 기반 고체 산화물 연료전지의 연료극 중간층으로 적용한 결과를 보여준다. $500^{\circ}C$ 이상의 고온에서는 산화 세륨계 전해질의 전기전도도가 상승하여 이를 전해질로 사용한 고체 산화물 연료전지의 개회로 전압이 하강하고 성능이 저하된다. 원자층 증착법을 이용해 연료극 측 전해질 표면에 증착된 YSZ 박막은 얇은 두께(60 nm)에도 불구하고 산화 세륨계 전해질 표면을 완벽하게 도포함으로써, 전해질을 관통하는 전자의 흐름을 막아 개회로 전압을 최대 20%까지 상승시켰다. 이를 통해 $500^{\circ}C$에서의 최대 전력 밀도는 52%가 상승하였다.