• Title/Summary/Keyword: Ion Conductivity

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Electrochemical Method for Measurement of Hydroxide Ion Conductivity and CO2 Poisoning Behavior of Anion Exchange Membrane (음이온 교환막의 정확한 OH-전도도 및 CO2 피독 효과 분석을 위한 전기화학적 측정법)

  • Kim, Suyeon;Kwon, Hugeun;Lee, Hyejin;Jung, Namgee;Bae, Byungchan;Shin, Dongwon
    • Journal of the Korean Electrochemical Society
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    • v.25 no.2
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    • pp.88-94
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    • 2022
  • The anion exchange membrane used in alkaline membrane fuel cells transports hydroxide ions, and ion conductivity affects fuel cell performance. Thus, the measurement of absolute hydroxide ion conductivity is essential. However, it is challenging to accurately measure hydroxide ion conductivity since hydroxide ions are easily poisoned in the form of bicarbonate by carbon dioxide in the atmosphere. In this study, we applied electrochemical ion exchange treatment to measure the absolute hydroxide ion conductivity of the anion exchange membrane. In addition, we investigated the effect of carbon dioxide poisoning of hydroxide ions on electrochemical performance by measuring bicarbonate conductivity. Commercial anion exchange membranes (FAA-3-50 and Orion TM1) and polyphenylene-based block copolymer (QPP-6F) were used.

Analysis of Rainwater Samples in Cheju (제주도에서의 빗물 이온 농도 분석)

  • 심상규;강창희;김용표
    • Journal of Korean Society for Atmospheric Environment
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    • v.10 no.2
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    • pp.98-104
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    • 1994
  • Precipitation samples were collected at Kosan, Cheju Island over a period of 6 months An automatic rain sampler was manufactured domestically and installed at Kosan station. All samples were collected on a weekly basis. Samples were analyzed for S $O_4$$^{=}$, N $O_3$$^{[-10]}$ , C $l^{[-10]}$ , N $H_4$$^{+}$, N $a^{+}$, $K^{+}$, $Ca^{++}$, $Mg^{++}$, and pH and specific conductivity. The quality analysis of rain sample data were performed based on ion balance and specific conductivity. The pH of rain samples ranged between 4.6 to 6.6. Bicarbonate ion concentration were included in ion balance and specific conductivity calculations. The sum of cation concentrations were slightly greater than the sum of anion concentrations. Calculated specific conductivity was greater than measured specific conductivity. The most probable explanations for this discrepancy is "an anion too low or anion missing." Two criteria were used to identify outliners. They are 1) the difference between the sum of anion concentrations and cation concentration is more than 50 $\mu$eq./1 and 2) the difference between calculated and measured specific conductivity is more than 25%. Chemical analysis from several samples did not satisfy these quality control criteria. Volume weighted average concentrations were calculated. Dominant free acids in rain samples were N $a^{+}$, C $l^{[-10]}$ , S $O_4$$^{=}$, N $O_3$$^{[-10]}$ ions in order of abundance. Non-seasalt sulfate comprises 76% of total sulfate.sulfate.e.ate.e.

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Electric Conductivities of LaCl3-KCl Binary Melts (용융 LaCl3-KCl 2성분계 혼합염의 전기전도도)

  • Kim, Kiho
    • Journal of the Korean institute of surface engineering
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    • v.47 no.1
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    • pp.48-52
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    • 2014
  • Electric conductivities of $LaCl_3$-KCl binary melts have been measured by the Kohlausch bridge method over the range from their liquidus temperatures to about 1280 K. The electric conductivity increased with the content of KCl for all over the composition range of binary melts. The composition dependence of the electric conductivity and molar conductivity for the binary melt showed a non-linear relation from the additivity line, and the deviation showed a maximum value at about 60 mol.% KCl. The deviation implies the existence of complex ion of $LaCl^{4-}$ in the melt. Activation energy for electric conductivity of the binary melts decreased monotonously with increasing content of KCl.

Electric Conductivities of LaC $l_3$-LiCl Binary Melts (용융 LaC $l_3$-LiCl 2성분계 혼합염의 전도도)

  • Kim Ki-Ho
    • Journal of the Korean institute of surface engineering
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    • v.37 no.5
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    • pp.301-306
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    • 2004
  • Electric Conductivities of $LaCl_3$-LiCl binary melts have been measured by the Kohlausch bridge method over the range of their liquidus temperatures to about 1200 K. The electric conductivity increases with the content of LiCl for all over the composition range of binary melts. Composition dependence of the electric conductivity and molar conductivity for the binary melt shows a non-linear relation from the additivity line, and the deviations displays a maximum value at about 60 mol % LiCl. This suggest the existence of the complex ion of$ LaCl_{4}^{-}$ in the melt. Activation energy for electric conductivity of the binary melts decrease monotonously with increasing content of LiCl.l.

UNCERTAINTIES INVOLVED IN THE IONOSPHERIC CONDUCTIVITY ESTIMATION (전리층 전기전도도의 추정과 관련된 불확실성)

  • 곽영실;안병호
    • Journal of Astronomy and Space Sciences
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    • v.19 no.4
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    • pp.243-254
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    • 2002
  • Various uncertainties involved in ionospheric conductivity estimation utilizing the electron density profile obtained from the Sondrestrom incoherent scatter radar are examined. First, we compare the conductivity which is based on raw electron density and the one based on corrected electron density that takes into account the effects of the difference between the electron and ion temperatures and the Debye length. The corrected electron density yields higher Pedersen and Hall conductivities than the raw electron density does. Second, the dependence of collision frequency model on the conductivity estimation is examined. Below 110 km conductivity does not depend significantly on collision frequency models. Above 110 km, however, the collision models affect the conductivity estimation. Third, the influence of the electron and ion temperatures on the conductivity estimation is examined. Electron and ion temperatures carrying an error of about 10% do not seem to affect significantly the conductivity estimation. Fourth, also examined is the effect of the choice of the altitude range of integration in calculating the height-integrated conductivity, conductance. It has been demonstrated that the lower and upper boundaries of the integration are quite sensitive to the estimation of the Hall and Pedersen conductances, respectively.

Electrical Conductivity Properties of the Vacuum Forming Packing Materials by Ion Implantation (이온주입에 의한 진공성형 포장재의 전기전도 특성)

  • 이재형;이찬영;길재근
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.16 no.11
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    • pp.1055-1061
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    • 2003
  • A study has been made of surface modification of various organic materials by ion implantation to increase the surface electrical properties. The substrate used were PP(polypropylene), PET(polyethylene teraphthalate), ECOP(ethylene copolyester), PS(polystyrene). N$_2$, Ar ion implantation was performed at energies of 40 and 50keV with fluences from 5${\times}$ 10$\^$15/ to 7${\times}$10$\^$16/ ions/$\textrm{cm}^2$ with and without H$_2$O gas environment. Surface resistance decrease of implanted polymers was affected by ion implantation energy, ion species, atmosphere of chamber and kind of polymer. In result, surface conductivity of polymers irradiated with atmosphere gas H$_2$O was 10 times more higher than normal vacuum atmosphere, but after 90 hours, surface conductivity returned to the without H$_2$O gas atmosphere condition caused by aging effect. After vacuum forming, surface resistance value was changed to over 10$\^$16/$\Omega$/$\square$, because creation of surface cracks.

Controlling Defects in Graphene Film for Enhanced-Quality Current Collector of Zinc-Ion Batteries with High Performance (고성능 아연-이온 전지의 고품질 집전체를 위한 그래핀 필름의 결함 제어)

  • Young-Geun Lee;Geon-Hyoung An
    • Korean Journal of Materials Research
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    • v.33 no.4
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    • pp.159-163
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    • 2023
  • Zinc-ion Batteries (ZIBs) are currently considered to be effective energy storage devices for wearable electronics because of their low cost and high safety. Indeed, ZIBs show high power density and safety compared with conventional lithium ion batteries (LIBs) and exhibit high energy density in comparison with supercapacitors (SCs). However, in spite of their advantages, further current collector development is needed to enhance the electrochemical performance of ZIBs. To design the optimized current collector for high performance ZIBs, a high quality graphene film is suggested here, with improved electrical conductivity by controlling the defects in the graphene film. The graphene film showed improved electrical conductivity and good electron transfer between the current collector and active material, which led to a high specific capacity of 346.3 mAh g-1 at a current density of 100 mA g-1, a high-rate performance with 116.3 mAh g-1 at a current density of 2,000 mA g-1, and good cycling stability (68.0 % after 100 cycles at a current density of 1,000 mA g-1). The improved electrochemical performance is firmly because of the defects-controlled graphene film, leading to improved electrical conductivity and thus more efficient electron transfer between the current collector and active material.

Electrical Properties of PET(polyethylene teraphthalate) by Ion Implantation (이온주입에 의한 PET(polyethylene teraphthalate)의 표면결합상태 변화와 표면전기전도도 특성)

  • 이재형;길재근
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.53 no.7
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    • pp.382-386
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    • 2004
  • A study has been made of surface modification of organic materials by ion implantation to increase the surface electrical properties. The substrate used were PET(polyethylene teraphtalate). N$^{+}$, Ar$^{+}$ implantation was peformed at energies of 40 keV and 50 keV with fluences from $5{\times}10^{15}$, $1{\times}10^{16}$,$7{\times}10^{16}$, $1{\times}10^{17}$/ ions/$cm^2$. UV/Vis, FT-IR and XPS spectroscopy measured for surface structure changes. Surface resistance decrease of implanted polymers was affected by ion implantation energy, ion species and ion dose rate. Surface conductivity of PET increased $2{\times}10^{9}$/∼$2{\times}10^{10}$/$\Omega$/sq by ion implantation. Result of various spectroscopy analysis, the cause of increasing PET surface conductivity was expected to breaking C=O bonds. It was formation carbon network structure by promote cross-linking and create C-C, C=C bonds.

Effect of Li3BO3 Additive on Densification and Ion Conductivity of Garnet-Type Li7La3Zr2O12 Solid Electrolytes of All-Solid-State Lithium-Ion Batteries

  • Shin, Ran-Hee;Son, Sam-Ick;Lee, Sung-Min;Han, Yoon Soo;Kim, Yong Do;Ryu, Sung-Soo
    • Journal of the Korean Ceramic Society
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    • v.53 no.6
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    • pp.712-718
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    • 2016
  • In this study, we investigate the effect of the$Li_3BO_3$ additive on the densification and ionic conductivity of garnet-type $Li_7La_3Zr_2O_{12}$ solid electrolytes for all-solid-state lithium batteries. We analyze their densification behavior with the addition of $Li_3BO_3$ in the range of 2-10 wt.% by dilatometer measurements and isothermal sintering. Dilatometry analysis reveals that the sintering of $Li_7La_3Zr_2O_{12}-Li_3BO_3$ composites is characterized by two stages, resulting in two peaks, which show a significant dependence on the $Li_3BO_3$ additive content, in the shrinkage rate curves. Sintered density and total ion conductivity of the system increases with increasing $Li_3BO_3$ content. After sintering at $1100^{\circ}C$ for 8 h, the $Li_7La_3Zr_2O_{12}-8$ wt.% $Li_3BO_3$ composite shows a total ionic conductivity of $1.61{\times}10^{-5}Scm^{-1}$, while that of the pure $Li_7La_3Zr_2O_{12}$ is only $5.98{\times}10^{-6}Scm^{-1}$.