• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.33 no.5
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• pp.411-417
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• 2020

In this study, we introduce a Na β"-alumina composite thick film as a solid electrolyte, to reduce the resistance of electrolyte for a Na/S battery. An alumina/zirconia composite material was used to enhance the mechanical properties of the electrolyte. A solid electrolyte of about 40 ㎛ thick was successfully fabricated through the conversion and tape-casting methods. In order to investigate the effect of the surface treatment process of the solid electrolyte on the battery performance, the electrolyte was polished by dry and wet processes, respectively, and then the Na/S batteries were prepared for analyzing the battery characteristics. The battery with the dry process performed much better than the battery made with the wet process. As a result, the battery manufactured by the dry process showed excellent performance. Therefore, it is confirmed that the surface treatment process of the solid electrolyte has an important effect on the battery capacity and coulombic efficiency, as well as the interface reaction.

• Journal of the Korean Ceramic Society
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• v.40 no.3
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• pp.293-300
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• 2003

It was investigated that effect of suspension and electrolyte concentrations on zeta potential of alumini suspension and Iso-Electric Point(I.E.P.). The alumina powders in 0.1∼l $\mu\textrm{m}$ particle size distribution, and the electrolyte NH$_4$NO$_3$ were used for preparing the suspension and electrophoresis method was used for measuring zeta potential in this work. As the concentration of suspension was increased, zeta potential and the I.E.P. were increased, respectively. On the other hand, as the electrolyte concentration was increased, the I.E.P. was decreased. As a result of this work, the best condition for measuring zeta potential was the 0.01 wt% and 10 mM of the suspension and the electrolyte concentration, respectively.

• Journal of Electrochemical Science and Technology
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• v.10 no.1
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• pp.55-60
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• 2019

Herein, the effect of counter anions on the formation of a solid electrolyte interphase (SEI) in a propylene carbonate (PC)-based electrolyte solution was investigated. Although the reversible capacities were different, reversible intercalation and de-intercalation of lithium ions occurred in the graphite negative electrode in the PC-based electrolyte solutions containing 1 M $LiClO_4$, $LiPF_6$, $LiBF_4$, and $LiCF_3SO_3$ at low temperature ($-15^{\circ}C$). This indicated that the surface films acted as an effective SEI to suppress further co-intercalation and decomposition reactions at low temperature. However, the SEIs formed at the low temperature were unstable in 1 M $LiPF_6$ and $LiBF_4/PC$ at room temperature ($25^{\circ}C$). On the other hand, increasing reversible capacity was confirmed in the case of $LiCF_3SO_3/PC$ at room temperature, because the SEI formed at the low temperature was still maintained. These results suggest that counter anions are an important factor to consider for the formation of effective SEIs in PC-based electrolyte solutions.

• YAKHAK HOEJI
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• v.20 no.3
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• pp.156-161
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• 1976

The salting in and salting out of Octoxynol, N.F., a nonionic polyoxyethylated surfactant by n-alkylamine hydrochlorides ws investigated by measuring their effect on the cloud point of the surfactant at various salt concentrations. The carbon number of the alkyl chain was varied from zero to twelve. Ammonium chloride, methylamine hydrochloride and ethylamine hydrochloride tended to salt out the surfactant, lowering its cloud point in proportion to the salt concentration. n-Ankylamine and n-butylamine hydrochlorides showed salting-out effect at low concentrations of the electrolyte, while their effects were leveled off and showed rather salting-in trend at higher concentrations of the electrolyte. These salting-in effect was ascribed to the formation of a hydrotropy of the n-alky lammonium cations with the surfactant. The higher homolog compounds of n-alkylamine hydrochlorides showed extraordinarily high salting-in effect at very low oncentrations of the electrolyte. These large salting-in effects were more drastic as the chain length was getting longer. These large increases of the cloud point of the surfactant were attributed to the formation of mixed micelles of n-alkylammonium cations with the polyoxyethylated surfactant.

• Journal of Electrochemical Science and Technology
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• v.9 no.2
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• pp.99-108
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• 2018

Proton exchange membrane (PEM) water electrolysis systems offer several advantages over traditional technologies including higher energy efficiency, higher production rates, and more compact design. In this study, all the experiments were performed with a self-designed PEM electrolyser operated at 1 atm and $25^{\circ}C$. Two types of electrolyte were used: (i) potassium hydroxide (KOH), and (ii) sulfuric acid ($H_2SO_4$). In the experiments, the voltage, current, and time were measured. The concentration of the electrolyte significantly affected the electrolyser performance. Overall the best case was with 15 wt% $H_2SO_4$ at the anode channel and 20 wt% at the cathode channel with. In addition, increasing the difference in concentration of the sulfuric acid had an effect on the diffusion. The diffusion flux became larger when the difference in concentration became larger, increasing electrolyser efficiency without the addition of extra energy.

• Journal of Electrochemical Science and Technology
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• v.14 no.2
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• pp.145-151
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• 2023

Planer-type electrolyte substrates are often utilized for stack manufacturing of electrolyte-supported solid oxide fuel cells (ES-SOFCs) to fulfill necessary requirements such as a high mechanical strength and redox stability. This work did an electrochemical analysis of ES-SOFC with different NiO-YSZ anode thicknesses to find the optimal value for the high performance of the fuel cell. The cell resistivities were constant at anode thickness between 25-58 ㎛, but a thick anode (74 ㎛) caused a high electrode resistivity leading to a dramatic reduction in cell performance. A stability test was performed for 50 hours at 700℃, and the results showed a degradation rate of 0.3% per 1000 h by extrapolated fitting.

• Journal of the Korean Society of Safety
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• v.13 no.4
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• pp.206-212
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• 1998

The water permeation in protective coatings, which may greatly influence the corrosion protective property of these coatings, was studied using the electrochemical impedance spectroscopy technique. During the absorption of water in protective coatings immersed in electrolyte solution, the change of coating capacitance with concentration of electrolyte was determined from impedance measurements. When water absorption or desorption of coatings occured by exposing the coatings to electrolyte solutions of different concentration, increase in impedance caused by desorption of water was found to be higher in the case of thicker film. The amount of water absorbed in coatings changed with concentration of electrolyte. The water taken up in coatings from the solution of lower electrolyte concentration was deserted by contact with the solution of higher concentration. The uptake of water in protective coatings varied depending on the type of coating ingredient especially binder.

• Korean Journal of Materials Research
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• v.17 no.5
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• pp.244-249
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• 2007

The properties of anodized films on aluminum 6061 alloy in single electrolyte of sulfuric acid and mixed electrolyte of sulfuric-boric acid and sulfuric-boric-nitric acid have been studied. Polarization tests in NaC solution were used to investigate the corrosion performance. Characteristics of film formation and surface morphology were examined by optical microscopy, FE-SEM and EDS. The results obtained have indicated that oxide films growth have been promoted by nitric acid and anodized films in mixed electrolyte have superior corrosion resistance. In case of anodic films formed in mixed electrolyte, some grooves and numerous crazings were also observed at the surface.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.617-620
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• 1999

To reduce the consumption of chemicals and ultra pure water(UPW) in cleaning process used in device manufacturing, we proposed wet processes that use electrolytic ionized water(EIW), which is generated by electrolysis of a diluted electrolyte solution or UPW and systemically investicate the EIW\`s characteristics. EIW\`s pH values are increased in cathode chamber and decreased in anode chamber according to the electrolysis time and its varied ratio is reduced with time increasement. The variation of pH and ORP is increased accordin to the applied voltage until critical voltage. But more than that voltage, the variation is decreased because of ion\`s scattering effect. When electrolyte is added, the effects of electrolysis is increased because electrolyte acts as catalyst. But when the density of electrolyte is increased more than critical value, ion\`s flowage is obstructed and the effects of electrolysis is decreased.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.5
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• pp.384-393
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• 1998

A mixed powder of electrolyte and matrix support materials with a proper proportion was used for the fabrication of an electrolyte matrix sheet. The purpose of this study is to reduce the large change in MCFC cell thickness occurring in the initial start-up period when separate sheets of electrolyte and support are used. A focus was put on how small the carbonate particles could be made. The particle size of the carbonate powder was controlled by ball milling and the distribution was measured using a particle size analyser. The thickness change was reduced to 20% by this approach, which could be compared to 27% observed in a conventional cell. The thickness changes of electrolyte matrix have linear relation sizes of carbonate powders.