• Journal of the Korean Electrochemical Society
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• v.5 no.4
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• pp.192-196
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• 2002

Ionic liquids based on l-ethyl-3-methylimidazolium cation $(EMI^+)$ and inorganic or organic anions containing fluorine atoms were applied to electrolyte materials for double-layer capacitors. The double-layer capacitors composed of a pair of activated carbon electrodes and an ionic liquid selected from $EMIBF_4,\; EMINbF_6,\;EMITaF_6,\;EMICF_3SO_3,\;EMI(CF_3SO_2)_2N,\;and\;EMI(C_2F_5SO_2)_2N$ showed inferior low-temperature characteristics to those of a conventional nonaqueous electrolyte based on propylene carbonate (PC) solvent. On the other hand, the capacitor using $EMIF{\cdot}2.3HF$ showed excellent low-temperature characteristics due to its high conductivity at low temperatures, however, it had a lower working voltage $(\~2V)$ than the conventional nonaqueous counterpart $(\~3V)$.

• Journal of the Korean Wood Science and Technology
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• v.45 no.3
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• pp.268-277
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• 2017

In this study, lignocellulose nanofibrils (LCNFs) were prepared from Pussy willow wood powder by disk-milling after pretreatment using the cosolvent of 1-ethyl-3-methylimidazolium acetate ([EMIM]Ac) and N,N-dimethylformamide (DMF) with different mixing ratios for different time. All pretreated samples showed native cellulose I polymorph and cellulose crystallinity was lowest when cosolvent of DMF with 30% [EMIM]Ac was used. Average crystallite size of raw material and the pretreated product by MDF and its cosolvent with 10% [EMIM]Ac was found to be about 3.2 nm and decreased with increasing pretreatment time at the DMF cosolvent with 30% [EMIM]Ac. Defibrillation efficiency was improved by loosening wood cell wall structure by the pretreatment using co-solvent system of [EMIM]Ac and DMF.

• Membrane Journal
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• v.29 no.3
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• pp.164-172
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• 2019

In this work, we demonstrate a facile process to prepare an electrolyte membrane for the supercapacitor based on a graft copolymer consisting of starch and poly(acrylonitrile) (PAN). The graft copolymer (starch-g-PAN) was synthesized via free radical polymerization initiated by ceric ions. The starch-g-PAN was dissolved in ionic liquid, i.e. 1-ethyl-3-methylimidazolium dicyanamide (EMIM DCA) without any organic solvents at room temperature. The gelation of polymer electrolyte membranes occurred by applying high temperature, i.e. $100^{\circ}C$ for 1 hour. The resultant electrolyte membrane was flexible and thus applied to flexible solid supercapacitors. The performance of the supercapacitor based on starch-g-PAN graft copolymer electrolyte reached 21 F/g at a current density of 0.5 A/g. The cell also showed high cyclic stability with 86% of retention rate within 10,000 cycles. The preparation of starch-g-PAN based polymer electrolyte membrane provides opportunities for facile fabrication of flexible solid supercapacitors with good performance.

• Journal of the Korean Wood Science and Technology
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• v.48 no.3
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• pp.405-413
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• 2020

Recycling of ionic liquid (1-ethyl-3-methylimidazolium acetate, [EMIM]Ac) after the pretreatment of Salix gracilistyla Miq. was conducted and the effect of the recycling number on the enzymatic saccharification yield was investigated. Enzymatic saccharification was performed using an enzyme cocktail (Acremonium cellulase and Optimash BG) at 50 ℃ for 72 h. All recycled [EMIM]Ac samples showed a lower amount of water soluble fraction than pure [EMIM]Ac. On increasing the recycling number from 1 to 4, the amount of water soluble fraction decreased from 18% to 15%. The X-ray diffraction pattern of the products pretreated with recycled [EMIM]Ac showed cellulose I crystalline polymorph. The crystallinity of the product pretreated with recycled [EMIM]Ac was 47-49%, which was lower than 33% of that with pure [EMIM]Ac. The yields of glucose and xylose decreased in the pretreatment with recycled [EMIM]Ac compared to that with pure [EMIM]Ac.

• Journal of the Korean Electrochemical Society
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• v.5 no.4
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• pp.178-182
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• 2002

The electrochemical behavior of binder-free carbon anode, comprising of only artificial and natural graphite (AG and NG) particles, for intercalation and deintercalation of lithium ion $(Li^+)$ in aluminum chloride (AICI_3)-I-ethyl­3-methylimidazolium chloride (EMIC)-lithium chloride (LiCl)-thionyl chloride $(SOCI_2)$ room-temperature molten salt (RTMS) was studied. Binder-free carbon electrodes were fabricated using electrophoretic deposition (EPD) method. The binder-free carbon anodes provided a relatively flat charge and discharge potentials $(0\;to\;0.2V\;vs.\;Li/Li^+)$ and current capabilities $(250-340mAh{\cdot}g^{-1})$ for the intercalation and deintercalation of $Li^+$. Stability of the binder-free carbon anodes for intercalation and deintercalation of 50 cycles was confirmed.

• Nuclear Engineering and Technology
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• v.54 no.5
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• pp.1597-1605
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• 2022

A porous silica-based adsorbent was prepared by impregnating the pores of a silica support with the extractant 1,3-[(2,4-diethylheptylethoxy)oxy]-2,4-crown-6-calix[4]arene (Calix[4]arene-R14) and an additive agent 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (C₂mim ⁺ NTf^-₂) as the materials to remove cesium(I) (Cs⁺) ions from seawater. The as-prepared adsorbent showed excellent adsorption performance toward Cs⁺ ions, with adsorption equilibrium reached within 2 h and an adsorption amount of 0.196 mmol/g observed. The solution pH, temperature, and the presence of coexisting metal ions were found to have almost no effect on Cs⁺ adsorption. The adsorption mechanism was considered to proceed via ion exchange between Cs⁺ and C₂mim⁺. In addition, the particle-induced X-ray emission analysis results further clarified that the adsorbed Cs⁺ ion species on the adsorbent was in the form of both CsCl and CsBr.

• Journal of the Korean Electrochemical Society
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• v.5 no.4
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• pp.183-188
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• 2002

The structure of species formed in $NbCI_5-I-ethyl-3-methylimidazolium$ chloride (EMIC) room-temperature molten salt (RTMS) was examined with the Raman spectroscopic measurement and ab initio molecular orbital calculation. The equilibrium structures of $NbCl_5,\;NbCl_6^-,\;Nb_2CI_{10},\;Nb_2CI_{11}^-,\;Nb_3CI_6^-,\;NbCI_6^--EMI^+\;(in\;which\;NbCI_6^-$ anion approaches $EMI^+$ cation with strong interaction) and $Nb_2CI_{11}^--EMI^+$ were obtained with the HF/LANL2DZ level of calculation. The harmonic frequencies at each equilibrium structure were compared with Raman spectra. The harmonic frequencies of $NbCI_6^--EMI^+,\; Nb_2CI_{11}^--EMI^+,\;and\;Nb_2CI_{10}$ were in good agreement with the Raman spectra of RTMS melts. In the $NbCI_5-EMIC RTMS$, the main species were $NbCI_6^-\;and\;EMI^+$. In the $NbCl_5-EMIC$ RTMS added $NbCl_5\;over\;50mol\%$, small amount of $Nb_2CI_{11}^-\;and\; Nb_2CI_{10}$ were also formed. The structures of anions and cation in the RTMS distorted from free ions with Coulomb force.

• Journal of the Korean Electrochemical Society
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• v.14 no.1
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• pp.9-15
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• 2011

The composite membranes comprising of sulfonated polymers as matrix and ionic liquids as ion-conducting medium in replacement of water are studied to investigate the effect of annealing of the sulfonated polymers. The polymeric membranes are prepared on recast Nafion containing the ionic liquid, 1-ethyl-3-methylimidazolium tetrafluoroborate ($EMIBF_4$). The composite membranes are characterized by thermogravitational analyses, ion conductivity and small-angle X-ray scattering. The composite membranes annealed at $190^{\circ}C$ for 2 h after the fixed drying step showed better ionic conductivity, but no significant increase in thermal stability. The mean Bragg distance between the ionic clusters, which is reflected in the position of the ionomer peak (small-angle scattering maximum), is larger in the annealed composite membranes containing $EMIBF_4$ than the non-annealed ones. It might have been explained to be due to the different level of ion-clustering ability of the hydrophilic parts (i.e., sulfonic acid groups) in the non- and annealed polymer matrix. In addition, the ionic conductivity of the membranes shows higher for the annealed composite membranes containing $EMIBF_4$. It can be concluded that the annealing of the composite membranes containing ionic liquids due to an increase in ion-clustering ability is able to bring about the enhancement of ionic conductivity suitable for potential use in proton exchange membrane fuel cells (PEMFCs) at medium temperatures ($150-200^{\circ}C$) in the absence of external humidification.