• Journal of Powder Materials
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• v.31 no.1
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• pp.23-29
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• 2024

This study investigates the effect of the microstructure of Li_1.3Al_0.3Ti_1.7(PO₄)₃ (LATP), a solid electrolyte, on its ionic conductivity. Solid electrolytes, a key component in electrochemical energy storage devices such as batteries, differ from traditional liquid electrolytes by utilizing solid-state ionic conductors. LATP, characterized by its NASICON structure, facilitates rapid lithium-ion movement and exhibits relatively high ionic conductivity, chemical stability, and good electrochemical compatibility. In this study, the microstructure and ionic conductivity of LATP specimens sintered at 850, 900, and 950℃ for various sintering times are analyzed. The results indicate that the changes in the microstructure due to sintering temperature and time significantly affect ionic conductivity. Notably, the specimens sintered at 900℃ for 30 min exhibit high ionic conductivity. This study presents a method to optimize the ionic conductivity of LATP. Additionally, it underscores the need for a deeper understanding of the Li-ion diffusion mechanism and quantitative microstructure analysis.

• Korean Chemical Engineering Research
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• v.48 no.1
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• pp.1-9
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• 2010

Since carbon dioxide, $CO_2$, was revealed as a major greenhouse gas, techniques for its separation, capture, and storage have received increasing interest in recent years. Aqueous amines are the most widely accepted $CO_2$ absorbents, but they cause the problems such as high regeneration energy, thermal degradation, and loss of absorbents due to their volatility. Ionic liquids having high thermal stability, extremely low vapor pressure, and capability of selectively absorbing specific gases have been proposed as new $CO_2$ capturing solvents which may potentially replace aqueous amines. By reviewing the ionic liquids having capability to absorb $CO_2$ reported in previous papers, we seek to develop a comprehensive understanding on the factors that influence the $CO_2$ solubility in ionic liquids such as their structures, absorption temperature, pressure, water content, etc., and to estimate the potential of ionic liquids as $CO_2$ separating media.

• Korean Journal of Materials Research
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• v.22 no.5
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• pp.227-236
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• 2012

Ionomer is a thermoplastic that is composed of covalent bonds and ionic bonds. It is possible to use this material in processes such as injection molding or extrusion molding due to the material's high oil resistance, weatherproof characteristics, and shock resistance. In this study, a new ionomer having a multifunctional group was prepared by a stepwise neutralization system with the addition of acidic and salt additives. In step I, to increase the contents of the multifunctional group and the acid degree in ethylene acrylic acid (EAA), MGA was added to the ionomer resin (EAA). A new ionomer was prepared via the traditional preparation method of the ionic cross-linking process. In step II, metal salt was added to the mixture of EAA and MGA. The extrusion process was performed using a twin extruder (L/D = 40, size : ${\varphi}30$). Ionomer film was prepared for evaluation of gas permeability by using the compression molding process. The degree of neutralized and ionic cross-linked new ionomer was confirmed by FT-IR and XRD analysis. In order to estimate the neutralization of the new ionomer film, various properties such as gas permeation and mechanical properties were measured. The physical strength and anti-scratch property of the new ionomer were improved with increase of the neutralization degree. The gas barrier property of the new ionomer was improved through the introduction of an ionic site. Also, the ionic degree of cross-linking and gas barrier property of the ionomer membrane prepared by stepwise neutralization were increased.

• Applied Chemistry for Engineering
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• v.32 no.3
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• pp.277-282
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• 2021

Two hydrophobic imidazolium based ionic liquids including 1-benzyl-3-butylimidazolium hexafluorophosphate [BzBIM]PF₆ and 1-pentyl-3-butylimidazolium hexafluorophosphate [PBIM]PF₆ having the same anion and different cation parts were synthesized. The structural composition of these ionic liquids were confirmed with Fourier-transform infrared spectroscopy (FT-IR) and proton nuclear magnetic resonance (¹H-NMR). Their physiochemical properties such as viscosity, ionic conductivity and thermal stability alongside electrochemical potential window range for both ionic liquid electrolytes were characterized and compared to each other. The overall results revealed that [BzBIM]PF₆ has higher thermal and electrochemical stabilities and viscosity than that of [PBIM]PF₆ probably due to the presence of benzyl ring in the imidazolium cation providing strong intermolecular π-π interactions.

• Bulletin of the Korean Chemical Society
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• v.28 no.9
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• pp.1567-1572
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• 2007

New pyrrolidinium and piperidinium bis(trifluoromethanesulfonyl)imide (TFSI) ionic liquids (ILs) having allyl substituents were synthesized and characterized. All of them are liquid at room temperature and stable up to 300 oC. The pyrrolidinium-based ILs showed better conductivities and lower viscosities than the corresponding piperidinium-based ILs. Among them, 1-allyl-1-methylpyrrolidinium TFSI showed the lowest viscosity of 52 cP, the highest conductivity of 5.7 mS cm?1, and the most negative cathodic voltage window of ?3.2 V (vs. Fc/Fc+) on a platinum electrode, which are the improved results compared to the corresponding analogue having a saturated substituent, 1-methyl-1-propylpyrrolidinium TFSI.

• Bulletin of the Korean Chemical Society
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• v.32 no.5
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• pp.1635-1639
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• 2011

An efficient and novel positive charge-doping on the sidewalls of multi-walled carbon nanotubes has been achieved in the presence of tetrahydrofuran as a dopant and Lewis acidic ionic liquids, [bmim]$Sb_nF_{5n+1}$ (n ${\geq}$ 2; bmim = 1-butyl-3-methylimidazolium), as an activator, leaving air-stable derivatives having positively charged sidewalls and the counter anions, [MWCNT$^{y+}$][SbF$_6^-$]$_y$ (MWCNT = multi-walled carbon nanotube). The derivatization took place very fast in one-pot and under mild reaction conditions. The ionic structure enabled a tunable dissolution of the derivatives in various solvents through anion exchange.

• Bulletin of the Korean Chemical Society
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• v.31 no.7
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• pp.1937-1940
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• 2010

Ionic liquids with halide anions were prepared and the dependency of halide anions on the $SO_2$ solubility of ILs was investigated. The study shows that the $SO_2$ solubility of ionic liquids lies in the range 1.91~2.22 $SO_2$/ILs mol ratio. $SO_2$ solubility in ionic liquids with varying halide anions follows the order Br > Cl > I. Theoretical investigation was also conducted at the B3LYP level using the Gaussian 03 program. From the theoretical consideration of the interaction between $SO_2$ and [EMIm]X (where X = Cl, Br, and I), it has been proposed that primary interaction of halide occurs with $C_2$-H of the imidazolium and S of $SO_2$. Experimental results further shows that the absorption and desorption process of $SO_2$ in ILs was reversible by the three cycles of the absorption at $50^{\circ}C$ and desorption at $140^{\circ}C$. The reversibility of $SO_2$ absorption was confirmed by FT-IR studies.

• Korean Chemical Engineering Research
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• v.44 no.5
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• pp.453-459
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• 2006

D-tryptophan and N-CBZ-D-phenylalanine were separated using ionic liquid as additives for the mobile phase in high performance liquid chromatography (HPLC). The ionic liquid of 1-butyl-3- methylimidazolium tetrafluoroborate (${[BMIm]}^+{[BF_4]}^-$) was used. Mobile phases were 65％, 70％, and 80％ methanol in water with addition of different concentrations (0.5, 1.0, 1.5, 2.0, 4.0, 6.0, 8.0, 10.0, 12.0, and 15.0 mmol/L) of the ionic liquid. The experiments were performed on stainless steel column, $3.9{\times}300mm$ i.d., packed with $15{\mu}m$ octadecyl-bonded silica gel at laboratory.The retention factor of D-tryptophan was not negligibly changed while that of N-CBZ-D-phenylalanine was decreased. The resolution between the two components were affected by the contents of methanol and ionic liquid in the mobile phase. With the small content of methanol and the high concentration of ionic liquid, the resolution was improved.

• Journal of Environmental Science International
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• v.28 no.8
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• pp.689-700
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• 2019

The adsorption and leaching characteristics of five ionic pesticides including four acidic pesticides (2,4-D, dicamba, MCPA, and MCPP) and one amphoteric pesticide (imazaquin) in agricultural soils were investigated. Soils around spring waters that were heavily affected by pesticide run-off and soils around wells considering the regional characteristics in Jeju Island were collected at 24 stations. The Freundlich constant, $K_F$ value, which is a measure of the adsorption capacity, decreased in the order of 2,4-D > MCPA > MCPP > dicamba > imazaquin. The adsorption capacity of these ionic pesticides decreased with increasing pH owing to the effects of ionization of pesticides and different ionizable functional groups of soils. The leaching of ionic pesticides in the soil column showed a reverse relationship with their adsorption in soils, namely, the ionic pesticides were leached more quickly for the pesticides with lower adsorption capacity. The groundwater contamination potential of the ionic pesticides was evaluated in the order of imazaquin > MCPA > MCPP > dicamba > 2.4-D according to the groundwater ubiquity score based on soil Koc and the half-life of the pesticide.

• Applied Chemistry for Engineering
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• v.16 no.5
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• pp.595-602
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• 2005

Ionic liquids (ILs) are the ionic salts pertaining to liquid-state at lower temperature than $100^{\circ}C$. ILs have attracted attention as new media because of their peculiar chemical, physical or electrical properties such as low volatility, nonflammability, liquid-phase stability at high temperature, high ability in solvating organic, inorganic or polymeric materials, and high ionic conductivity. Since the properties can be modified by assembling the pair using various anions and cations, ILs are often called designer solvents. In addition, ILs have been expected as new green media to replace the volatile organic solvents, which have been widely used in chemical, energy, material, and electronic industries, as well as to enhance the reaction activity and selectivity. In this review paper, the structures, properties, applications, and technology trend of ILS are introduced.