• Title, Summary, Keyword: Electrolyte

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Performance of molten carbonate fuel cell with Li-Na and Li-K carbonate electrolyte at extremely high-temperature condition

  • Lee, Ki-Jeong;Kim, Tae-Kyun;Koomson, Samuel;Lee, Choong-Gon
    • Korean Journal of Chemical Engineering
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    • v.35 no.10
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    • pp.2010-2014
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    • 2018
  • The cell performance of Li-K and Li-Na carbonate electrolytes was compared using a coin type molten carbonate fuel cell operated at the extremely high temperature of $800^{\circ}C$. It was an acceleration test to compare the performance in a short period. Electrochemical techniques such as steady state polarization (SSP) and impedance from the Nyquist plot were used in the cell performance analysis. The initial performance of both electrolytes was similar, but the performance of the Li-K electrolyte decreased drastically after 180 h. The results from SSP showed that the total overpotential of the Li-K electrolyte increased sharply, whereas that of Li-Na electrolyte had a continuous performance up to 340 h. The impedance analysis showed that the internal resistance of the Li-K electrolyte increased with time, but that of Li-Na electrolyte remained unchanged. The remaining amount of each electrolyte was determined, and it was observed that the electrolyte loss rate of the Li-K electrolyte was 0.0072 g/hr, and that of Li-Na electrolyte was 0.0028 g/hr. This implies that the electrolyte depletion rate of the Li-K electrolyte is about 1.5 times faster than that of the Li-Na electrolyte at the high-temperature condition. Thus, the cell of a Li-Na electrolyte containing MCFC according to the consumption of electrolyte is expected to be longer than one that uses Li-K electrolyte.

Effect of Electrolyte on Mechanical and Corrosion Properties of AZ91 Cast Magnesium Alloy Coated by Plasma Electrolytic Oxidation Method (플라즈마 전해 산화처리한 AZ91 주조마그네슘합금의 기계적 및 부식 특성에 미치는 전해질의 영향)

  • Kim, Bo-Sik;Lee, Du-Hyung;Chang, Si-Young
    • Journal of Korea Foundry Society
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    • v.29 no.5
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    • pp.233-237
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    • 2009
  • The effect of electrolyte on mechanical and corrosion properties of AZ91 magnesium alloy by plasma electrolytic oxidation (PEO) method was investigated. The coating layers formed in the silicate and the aluminate electrolytes showed porous structures. The small pores were randomly distributed on the coatings formed in aluminate electrolyte while the coatings formed in silicate electrolyte showed much bigger pores. In the aluminate electrolyte, the coatings were composed of Mg, MgO and $MgAl_2O_4$, whereas Mg, MgO, $MgAl_2O_4$ and $Mg_2SiO_4$ were identified in the coatings formed in silicate electrolyte. The hardness of coatings in the silicate electrolyte was higher than that of coating grown in the aluminate electrolyte. The AZ91 alloy coated in the silicate electrolyte had higher tensile strength and elongation than that coated in the aluminate electrolyte. In addition, the coatings formed in the silicate electrolyte showed much better corrosion resistance compared to the coatings formed in the aluminate electrolyte.

Modeling of Electrolyte Thermal Noise in Electrolyte-Oxide-Semiconductor Field-Effect Transistors

  • Park, Chan Hyeong;Chung, In-Young
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.16 no.1
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    • pp.106-111
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    • 2016
  • Thermal noise generated in the electrolyte is modeled for the electrolyte-oxide-semiconductor field-effect transistors. Two noise sources contribute to output noise currents. One is the thermal noise generated in the bulk electrolyte region, and the other is the thermal noise from the double-layer region at the electrolyte-oxide interface. By employing two slightly-different equivalent circuits for two noise current sources, the power spectral density of output noise current is calculated. From the modeling and simulated results, the bulk electrolyte thermal noise dominates the double-layer thermal noise. Electrolyte thermal noise are computed for three different concentrations of NaCl electrolyte. The derived formulas give a good agreement with the published experimental data.

Electrochemical studies of nano-scale solid electrolyte powder prepared by chemical synthesis process (화학적합성법에 의한 나노 고체 전해질 분말 합성 및 전기화학적 평가)

  • Kim, Young-Mi;Shin, Yu-Cheol;Kim, Ho-Sung
    • 한국신재생에너지학회:학술대회논문집
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    • pp.295-298
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    • 2009
  • Oxygen ionic conductors of CeScSZ electrolyte in SOFC unit cell are applied to anode and cathode as well as electrolyte to have the triple-phase-boundaries of electrochemical reaction, and it is required to decrease the sintering temperature of anode-supported electrolyte by the nanoscale of CeScSZ electrolyte powder. In this report, nanoscale CeScSZ electrolyte powder was synthesized by chemical synthesis method. The particle size, surface area and morphology of the powder were observed by SEM and BET. Thin film electrolyte of under $10{\mu}m$ was fabricated by tape casting using the synthesized CeScSZ electrolyte powder, and ionic conductivity and gas permeability 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, in which the active layer, measuring $20{\mu}m$, was introduced in the anode layer to provide a more efficient reaction. Electrochemical evaluations of the SOFC unit cell, including measurements such as power density and impedance, were performed and analyzed.

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Study on the Electrolyte for Zn-Br Redox Flow Battery (Zn-Br 레독스 흐름 전지용 전해액에 관한 연구)

  • Choi, Ho-Sang;Oh, Yong-Hwan;Ryu, Cheol-Hwi;Hwang, Gab-Jin
    • Transactions of the Korean hydrogen and new energy society
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    • v.24 no.4
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    • pp.347-352
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    • 2013
  • Four types of electrolyte were tested for the application as an electrolyte in the Zn-Br redox flow battery. Electrolyte was consist of $ZnBr_2$ (electrolyte number 1), $ZnBr_2+KCl$ (electrolyte number 2), $ZnBr_2+KCl+NH_4Br$ (electrolyte number 3) and $ZnBr_2+KCl+EMPBr(C_7H_{16}BF_4N)$ (electrolyte number 4). The each electrolyte property was measured by CV (cyclic voltammetry) method. The different between the potential of anodic and cathodic maximum current density in a CV experiment (${\Delta}E_P$) was 0.89V, 0.89V, 1.06V and 0.61V for the electrolyte number 1, 2, 3 and 4, respectively. The electrolyte involved KCl increased conductivity which was appeared by anodic and cathodic maximum current density in a CV experiment. It was estimated that the electrolyte of number 3 ($ZnBr_2+KCl+NH_4Br$) and number 4 ($ZnBr_2+KCl+EMPBr$) could be suitable as an electrolyte in the Zn-Br redox flow battery with non-appeared bubble, non-Br formation and high anodic-cathodic maximum current density.

Fabrication Characteristics and Electrochemical Studies of SOFC Unit Cell using ScSZ-based Electrolyte Powder prepared by Co-precipitation Synthesis (공침법에 의한 고체산화물연료전지용 ScSZ계 전해질의 제조공정 특성 및 전기화학적 평가)

  • Kang, Ju Hee;Lee, Ho Jae;Kim, Ho-Sung;Jeong, Jong Ho
    • 한국신재생에너지학회:학술대회논문집
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    • pp.138.2-138.2
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    • 2010
  • Scandium-doped zirconium, ScSZ-based electrolyte, provides higher oxygen conductivity than YSZ and nano-based electrolyte materials are ideal for fabricating thin film electrolyte membrane of SOFC unit cell. Moreover, it may be applied to anode and cathode as well as electrolyte as ionic conductor. In this report, nano-based ScSZ-based electrolyte powder was prepared by co-precipitation synthesis. The particle size, surface area and morphology of the powder were observed by SEM and BET. Thin film electrolyte of under $10{\mu}m$ was fabricated by tape casting and co-firing using the synthesized ScSZ-based powders, and ionic conductivity and gas permeability 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 evaluations of the SOFC unit cell, including measurements such as power density and impedance, were performed and analyzed.

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Improvement of Open Circuit Voltage (OCV) depending on Thickness of GDC Electrolyte of LT-SOFCs (저온형 SOFC용 GDC 전해질 두께에 따른 Open Circuit Voltage 향상)

  • Ko, Hyun-Jun;Lee, Jong-Jin;Hyun, Sang-Hoon
    • Journal of the Korean Ceramic Society
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    • v.47 no.2
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    • pp.195-198
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    • 2010
  • 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 mol% 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 $1200^{\circ}C$. And then, GDC electrolyte material was dip-coated on the anode and sintered at $1400^{\circ}C$. Finally the LSCF-GDC cathode material was screen-printed on the electrolyte and sintered at $1000^{\circ}C$. Electrolyte thickness was controlled by the number of dip-coating times. Open circuit voltage was measured depending on electrolyte thickness at $650^{\circ}C$ and found that the thicker GDC electrolyte was, the better OCV was.

Characteristics of Matrix Retaining Electrolyte in a Phosphoric Acid Fuel Cell Analyzed by A.C. Impedance Spectroscopy (복소임피던스법에 의한 인산형 연료전지용 전해질 매트릭스 특성)

  • 윤기현;장재혁;허재호;김창수;김태희
    • Journal of the Korean Ceramic Society
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    • v.32 no.2
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    • pp.189-196
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    • 1995
  • Materials retaining electrolyte of a phosphoric acid fuel cell (PAFC) have been prepared with SiC powder to SiC whisker mixing ratios of 1:1, 1:2, 1:3, 1:4, 0:1 by a tape casting method. When 3wt% dispersant (sorbitan monooleate) is added to a matrix, the porosity of the matrix decreases a little while the bubble pressure and area of the matrix increase remarkably in comparison with no dispersant content. Effect of the electrolyte resistance and the polarization resistance on perfomance of a PAFC has been investigated using A.C. impedance spectroscopy. With the increase of whisker content, the electrolyte resistance decreases due to the increase of porosity and acid absorbancy, and the polarization resistance increases due to the increase of surface roughness. The polarization resistance affects current density predominantly at the higher potential than 0.7V becuase the polarization resistance is considrably larger than the electrolyte resistance. Both the electrolyte resistance and the polarization resistance affect current density near 0.7V of the fuel cell operating potential because they have similar values. The electrolyte resistance affects current density predominantly at the lower potential than the fuel cell operating potential because the electrolyte resistance is larger than the polarization resistance.

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Study for Photovoltaic Characteristics of Gel Type Dye Sensitized Solar Cells (젤형 염료 태양전지의 광전변환 특성에 관한 연구)

  • Park, Byung-Wook;Kwak, Dong-Joo;Sung, Youl-Moon
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.23 no.2
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    • pp.168-174
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    • 2009
  • In this paper Gel polymer electrolyte using Poly(Vdf-HFP) was fabricated and compared with liquid type electrolyte. The chemical structure and ingredients of fabricated gel electrolyte was investigated and identified to gel polymer electrolyte by FTIR, gel electrolyte was verified to polymer state by SEM From the experiment result, the better component ratio of Propylene carbonate and Diethyl carbonate for gel type electrolyte was 5 : 5. The conversion efficiency of fabricated DSCs using gel electrolyte was $3{\sim}4[%]$, expected to alternate with liquid type electrolyte.

Deposition of Electrolyte for Intermediate Temperature Solid Oxide Fuel Cells by Combined Thin Film Deposition Techniques (복합 박막 증착 공정을 이용한 중저온 고체산화물 연료전지용 전해질 증착)

  • Ha, Seungbum;Jee, Sanghoon;Tanveer, Waqas Hassan;Lee, Yoonho;Cha, Suk Won
    • 한국신재생에너지학회:학술대회논문집
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    • pp.84.1-84.1
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    • 2011
  • Typical solid oxide fuel cells (SOFCs) have limited applications because they operate at high temperature due to low ionic conductivity of electrolyte. Thin film solid oxide fuel cell with yttria stabilized zirconia (YSZ) electrolyte is developed to decrease operating temperature. Pt/YSZ/Pt thin film SOFC was fabricated on anodic aluminum oxide (AAO). The crystalline structure of YSZ electrolyte by sputter is heavily depends on the roughness of porous Pt layer, which results in pinholes. To deposit YSZ electrolyte without pinholes and electrical shortage, it is necessary to deposit smoother and denser layer between Pt anode layer and YSZ layer by sputter. Atomic Layer Deposition (ALD) technique is used to deposit pre-YSZ layer, and it improved electrolyte quality. 300nm thick Bi-layered YSZ electrolyte was successfully deposited without electrical shortage.

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