• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 하계종합학술대회 논문집(2)
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• pp.76-79
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• 2000

The 3$\mu\textrm{m}$-thick PVDF (Polyvinyiidene fluoride) thin film have been prepared using physical vapor deposition with electric field, and its FT-IR specrum, dielectric property and electric conduction phenomenon have been investigated. Since the characteristic peaks ate detected at 509.45 and 1273.6〔cm〕 in the FT-IR spectrum, we are confirmed that the ${\beta}$ -phase is dominant in the PVDF thin film. In the results of dielectric properties, the PVDF thin film shows anomalous dispersion, i.e. gradual decrease of dielectric constant with increase of frequency, and also that the dielectric absorption point changes from 200Hz to 7000Hz with increasing temperature of thin film, which is consistent with the Debye's theory. The activation energy (ΔH) obtained from temperature dependence of dielectric loss is 21.64 ㎉/㏖. We confirm that the electric conduction mechanism of PVDF thin film is dominated by ionic conduction by investigating the dependence of the leakage current of the thin film on the temperature and the electric field.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 하계학술대회 논문집 A
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• pp.12-15
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• 1993

The correlation between electrical conduction and dielectric relaxation properties of copper ion conducting glasses is discussed. The glasses were prepared in the system $CuI-Cu_2S-Cu_2O-MoO_3$ using rapid quenching technique. These glasses have high ionic conductivities at room temperature in the range of $10^{\circ}$[S/m], and the conductivities increase with increasing CuI content. The activation energies for conduction are 0.26 - 0.57 eV. The dielectric relaxation times are 1 - 10uS, and the activation energy for ion jumping are 0.18 - 0.41eV. It is shown that the tendency of conduction properties depending on composition of the glass is similar those of dilectric relaxation.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 추계학술대회 논문집
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• pp.149-149
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• 2009

Generally, Nafion ionomer is used in the polymer electrolyte fuel cell (PEFC) electrodes to achieve high power density. At the high temperature operation of PEFC, however, ionic conductivity of Nafion remarkably decreased due to the evaporation of water in Nafion polymer. Recently, many researchers have focused on using the Ionic Liquids(ILs) instead of water in Nafion polymer. ILs have intrinsic properties such as good electrochemical stability, high ionic conductivity, and non-flammability. Especially, ILs play a crucial role in proton conduction by the Grottuss mechanism and act as water in water-free Nafion polymer. However, it was found that the ILs was leached out of the polymer matrix easily. In this study, we prepared membrane electrode assemblies with various contents of ILs. The effect of ILs in the electrode of each designed was investigated by a cyclic voltammetry measurement and the cell performance obtained through a single cell test using H2/Air gases. Electrodes with different contents of ILs in catalyst layer were examined at high temperature and low humidified condition.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 추계학술대회 논문집
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• pp.147-148
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• 2009

The water-like ionic liquids have been widely used to enable the proton conduction in ionic liquid based membranes at high temperature and anhydrous PEFCs. In this study, we synthesized various kinds of composite membranes based on hydrocarbon polymers having good thermal and mechanical stabilities at high temperatures and ionic liquids. The composite membrane consisting of hydrocarbon polymer and ionic liquid was characterized by thermogravimetric analyzer (TGA) and impedance spectroscopy. Consequently the non-aqueous composite membranes of a variety of hydrocarbon polymer and ionic liquids have good conductivity and thermal stability at high temperature conditions.

• 한국세라믹학회지
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• 제32권12호
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• pp.1357-1368
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• 1995

Nasigels of composition Na0.75Zr2PSi2O12 and Na3Zr2PSi2O12 have been synthesized by the sol-gel technique using metal alkoxide precursors. The monolithic dry gels of Na0.75Zr2PSi2O12 with no crack have been prepared by the control of the shrinkage rte, but gels of Na3Zr2PSi2O12 were impossible to prepare without cracking. The gels treated up to 80$0^{\circ}C$ led to the formtion of glass but the glasses were converted to the crystalline phases at above this temperature. Crystaline phases precipitated from the Na0.75Zr2PSi2O12 glass were NASICON-like phase, Na2Si2O5, and free Zirconia. Phase that precipitated from the Na3Zr2PSi2O12 was only rhombohedral NASICON. For Na0.75Zr2PSi2O12 gels, framework of PO4 tetrahedra and SiO4(PO4) tetrahedra formed at low temperature but changed to that of SiO4 and SiO4(PO4) tetrahedras as it were crystallized. In the case of Na3Zr2PSi2O12 gel, framework of isolated PO4 and SiO4 tetrahedras formed at low temperature but changed to SiO4(PO4) tetrahedra framework which usually formed in the NASICON crystal after crystallization at high temperature. The gels treated up to 80$0^{\circ}C$ contained the residual water. The ionic conduction was attributed to the motion of proton and Na+ ion at low (up to 150~20$0^{\circ}C$) and high temperatures, respectively. As the temperature of heat treatment increased, ionic conductivity gradaully increased with the extent of precipitation of crystalline phase.

• Korean Chemical Engineering Research
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• 제47권4호
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• pp.476-480
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• 2009

본 연구는 리튬 이차전지용 고분자 전해질 복합재료에 관한 것으로, 고분자는 poly(ethylene oxide)(PEO)와 poly(methyl methacrylate) (PMMA) 블렌드를 사용하고, 용매로는 Ethylene carbonate(EC), 그리고 $LiClO_4$를 리튬염으로 하는 전해질 복합체 필름을 제조하였으며, PMMA의 함유량에 따른 고분자 전해질의 전기화학적 특성을 관찰하였다. 제조된 고분자 전해질의 결정화도와 이온전도도는 시차주사열량계(DSC)와 주파수반응분석기(FRA)로 분석하였다. 그 결과 PMMA의 함량을 증가시킴에 따라서, PEO의 결정 영역이 감소하고 이온전도도가 증가하였다. 또한, PMMA의 함량이 20 wt.% 이상인 경우, 고분자 블렌드필름에서 상분리되는 현상을 관찰하였다. 즉, SEM 분석결과에 의해서, PMMA 주성분 영역과 PEO 주성분 영역의 구분이 가능하였다. 고분자 전해질의 이온전도도는 20 wt.% 첨가한 경우 가장 큰 이온전도도를 가지며, 함유량이 20 wt.% 이상에서는 PMMA 상의 증가로 인해 다소 감소된 이온전도도 변화를 나타내었다.

• 한국세라믹학회지
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• 제44권4호
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• pp.219-223
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• 2007

The ionic conductivity of $Li_2O-ZrO_2-SiO_2$ glasses has been designed and analyzed on the basis of a mixture design experiment with constraints. Fitted models for the activation energy and the ionic conductivity are as follows: $Q(kJ/moi)=54.8565x_1+144.825x_2+133.846x_3-170.908x_1x_3-334.338x_2x_3$ $log{\sigma}(300K)=-5.00245x_1-1.17876x_2-15.5173x_3+17.4522x_1x_3$. The electrical properties are very sensitive to the ratio of $Li_2O/SiO_2$. The effect of $ZrO_2$ is less than that of this ratio but $ZrO_2$ component attributes to the reduction of the activation energy. The optimal composition for best ionic conduction based on these fitted models is $55Li_2O{\cdot}10ZrO_2{\cdot}35SiO_2$. Its activation energy and ionic conductivity at 300 K are 46.98 kJ/mol and $1.08{\times}10^{-5}{\Omega}^{-1}{\cdot}cm^{-1}$, respectively.

• 한국재료학회지
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• 제18권11호
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• pp.617-622
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• 2008

In this study, the additivity factors of compositions to density and glass transition point ($T_g$) in a $xLi_2O-(1-x)[(1-y)TeO_2-yZnO]$ (0$T_g$ was discussed. As a method for predicting the relation between glass structure and ionic conductivity, density was measured by the Archimedes method. The glass transition point was analyzed to predict the relation between ionic conductivity and the bonding energy between alkali ions and non-bridge oxygen (NBO). The relation equations showing the additivity factor of each composition to the two properties are as follows: Density(g/$cm^3$) = $2.441x_1\;＋\;5.559x_2\;＋\;4.863x_3\;T_g(^{\circ}C)$ = $319x_1\;＋\;247x_2\;＋\;609x_3\;－\;1950x_1x_3$ ($x_1$ : fraction of $Li_2O$, $x_2$ : fraction of $TeO_2$, $x_3$ : fraction of ZnO) The density decreased as $Li_2O$ content increased. This was attributed to change of the $TeO_2$ structure. From this structural result, the electric conductivity of the glass samples was predicted following the ionic conduction mechanism. Finally, it is expected that electric conductivity will increase as the activation energy for ion movement decreases.

• 대한화학회지
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• 제31권4호
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• pp.301-307
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• 1987

600~$1050^{\circ}C$와 $1{\times}10^{-6}\~\1{\times}10^2\;torr$에서 고순도의 $La_2O_3$의 전기전도도가 연구되었다. 결합구조 및 반도체형이 온도 및 산소분압의 함수로 연구되었으며 위의 온도 및 산소압력의 영역에서 $La_2O_3$의 전도도값은 $1{\times}10^{-9}\~\1{\times}10^{-3}\(ohm{-}cm)^{-1}$ 로 나타났다. 전기전도도의 산소압력의존성은 $700^{\circ}C$에서 5.7, $1,000^{\circ}C$에서 5.3이며 $700^{\circ}C$이하의 낮은 오도영역에서는 9~14의 값은 나타내었다. 온도 감소에 따른 n값의 증가는 ${\alpha}-La_2O_3$의 전기전도가 단순한 전도메카니즘을 나타내지 않는다는 사실을 보여준다. 낮은 산소압력에서 전기운반체는 금속공위가 아니라 산소이온이다. 또한 낮은 온도영역에서 전기전도는 이온성을 띄며 높은 온도영역에서는 전자전도성을 나타낸다.

• 전기화학회지
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• 제23권2호
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• pp.47-55
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• 2020

고에너지 밀도의 리튬이온 이차전지를 구성하기 위하여 고로딩 LiCoO₂ 양극을 구성하였으며, 이의 전극설계를 다르게 하며 전기화학적 특성을 비교하였다. 기준로딩을 적용한 전극의 경우 약 2.2 mAh/㎠의 로딩값을 가지도록 하고, 고로딩 전극의 경우 약 4.4 mAh/㎠의 로딩값을 가지도록 전극을 제조하였다. 이때 도전재인 카본블랙의 함량과 전극의 기공도를 다르게 구성하여 전극 내의 전자전도도와 이온전도도가 고로딩 전극의 성능에 주는 영향을 비교하였다. 도전재의 함량이 증가할수록 전기화학적 성능이 향상될 것으로 기대하였으나, 도전재의 함량이 7.5 질량%까지 증가하게 되면 오히려 성능의 저하가 발생하였다. 이는 도전재가 충분히 제공된 경우에는, 동일한 로딩의 전극구성에서 활물질인 LiCoO₂ 구성비의 감소로 인해 전극두께가 증가하기 때문에 이로 인한 분극증가가 원인으로 판단된다. 그리고 전극의 기공도를 증가시키게 되면 이온전달의 경로는 확장될 수 있으나, 입자들 간의 접촉이 저하되고 전극의 두께가 증가하기 때문에 전극 내 전자전달은 불리하게 된다. 따라서, 전극의 압착을 강하게 하여 기공도를 낮출수록 전자전달이 개선되어 전지의 성능이 향상되었다. 고로딩 전극의 제조에 있어서는 전자전달의 경로를 충분히 확보하면서 전극두께를 감소시키는 전극설계가 필요하다.