• Applied Chemistry for Engineering
• /
• v.25 no.6
• /
• pp.559-563
• /
• 2014

It is well known that $CO_2$ can be dissolved easily in imidazolium-based room temperature ionic liquids (RTILs). Because of the high $CO_2$ solubility in RTILs, membranes containing RTILs can separate easily gas mixtures such as $CO_2/N_2$ and $CO_2/CH_4$. In this study, we prepared poly(vinylidene fluoride)-hexafluoropropyl copolymer (PVDF-HFP) gel membranes with several RTILs and measured permeabilities of several gases. When the anion of ionic liquids was tetrafluoroborate($BF{_4}^-$), both $CO_2$ permeability and selectivities decreased as the carbon number of the cation increased. When the cation of ionic liquids was 1-ethyl-3-methylimidazolium[emim], $CO_2$ permeability of gel membranes containing bis(trifluoromethane) sulfoneimide($Tf_2N^-$) anion was double compared to those containing tetrafluoroborate($BF{_4}^-$) anion. However, $CO_2/N_2$ and $CO_2/CH_4$ selectivities of the $Tf_2N^-$ case were decreased, whereas the $H_2$ selectivity was almost the same for two cases.

• Journal of the Korean Electrochemical Society
• /
• v.18 no.2
• /
• pp.51-57
• /
• 2015

We report the effect of the impurities including water and bromide in the propylmethylpyrrolidinium bis(trifluoromethanesulfonyl)imide (PMPyr-TFSI) on the electrochemical performance of lithium ion batteries. The several kinds of PMPyr-TFSI electrolytes with different amount of impurities are applied as the electrolyte to the cell with the high potential electrode, $LiNi_{0.5}Mn_{1.5}O_4$ spinel. It is found that the impurities in the electrolytes cause the detrimental effect on the cell performance by tracing the cycleability, voltage profile and Coulombic efficiency. Especially, the polarization and Coulombic efficiency go to worse by both impurities of water and bromide, but the cycleability was not highly influenced by bromide impurity unlike the water impurity.

• Journal of the Korean Electrochemical Society
• /
• v.3 no.3
• /
• pp.169-172
• /
• 2000

A new gel polymer electrolyte based on the modified polyacrylonitrile (PAN), polyacrylonitrile-co-bis[2-(2-methoxyethoxy)ethyl]itaconate (abbreviated as PANI) copolymer was synthesized in expectation of enhanced trapping ability of liquid electrolytes. PAN and PANI blend was complexed with organic solvents, ethylene carbonate (EC) and dimethyl carbonate (DMC), and $LiClO_4$ salt. The highest room temperature conductivity of $2\times10^{-3}\;Scm^{-1}$ was found for a film of 25PAN+10PANl+50EC/DMC+$15LiClO_4$. The solvent-rich crystalline part decreases due to the blending of PANI and therefore number of charge carriers increases giving higher ionic conductivity. The addition of PAM as a host polymer in the PAN-based gels has beneficial effects such as higher ionic conductivity, better thermal characteristics, better miscibility with solvent, wider electrochemical stability, and better interfacial stability with lithium electrode, though it exhibits slightly less mechanical rigidity.

• Polymer(Korea)
• /
• v.34 no.4
• /
• pp.357-362
• /
• 2010

Poly(ethyleneglycol diacrylate)(PEGDA) or 2-ethylhexyl acrylate(2EHA)-based gel polymer electrolytes(GPEs) which have a solid content in the range of 8～54 wt% were synthesized and their ionic conductivity and electrochemical properties were measured at room temperature. It was observed that the ionic conductivity over $1\times10^{-3}$ S/cm was obtained in a homogeneous PEGDA-based GPE with 21 wt% of solid content. However the electrochemical stability of the GPE was lower than that of a liquid electrolyte. The presence of AIBN initiator which can produce a N2 gas during polymerization process might be the reason of this low oxidation decomposition potential. As an alternative, benzoyl peroxide was used as an initiator and GPE with enhanced electrochemical stability was obtained. Finally, the formation of stable solid electrolyte interphase on a graphite anode was evidenced by cyclic voltammetry measurement.

• Membrane and Water Treatment
• /
• v.9 no.2
• /
• pp.79-85
• /
• 2018

In this work, batch adsorption of anionic dye acid green-25 (AG-25) from aqueous solution has been carried out at room temperature using anion exchange membrane (DF-120B) as a noval adsorbent. The effect of various experimental parameters such as contact time, membrane dosage, ionic strength and temperature on the adsorption of dye were investigated. Kinetic models namely pseudo-first-order, pseudo-second-order, Elovich, liquid film diffusion, Bangham and modified freundlich models were employed to evaluate the experimental data. Parameters like adsorption capacities, rate constant and related correlation coefficients for every model are calculated and discussed. It showed that adsorption of AG-25 onto DF-120B followed pseudo-first-order rate expression. Thermodynamic study indicates that adsorption of AG-25 onto DF-120B is an exothermic and spontaneous process.

• Journal of the Korean Electrochemical Society
• /
• v.14 no.1
• /
• pp.1-8
• /
• 2011

Ionic liquids are room-temperature molten salts, composed of organic mostly of organic ions that may undergo almost unlimited structural variation. We approach the new aspects of ionic liquids in applications where the semiconductor nanoparticles used as sensitizers of solar cells. We studied the effects of ionic liquids as capping ligand and/or solvent, on the morphology and phase of the CdSe/ZnS nanoparticles. Colloidal CdSe/ZnS nanoparticles were synthesized using a series of imidazolium ionic liquids; 1-R-3-methylimidazolium bis(trifluoromethylsulfonyl) imide ([RMIM][TFSI]), where R = ethyl ([EMIM]), butyl ([BMIM]), hexyl ([HMIM]), octyl ([OMIM]). The average size of nanoparticles was 8~9 nm, and both zinc-blende and wurtzite phase was produced. We also synthesized the nanoparticles using a mixture of trihexyltetradecylphosphonium bis(trifluoromethylsulfonyl)imide ([$P_{6,6,6,14}$][TFSI]) and octadecene (ODE). The CdSe/ZnS nanoparticles have a smaller size (5.5 nm) than that synthesized using imidazolium, and with a controlled phase from zinc-blende to wurtzite by increasing the volume ratio of [$P_{6,6,6,14}$][TFSI]. For the first time, the phase and size control of the CdSe/ZnS nanoparticles was successfully demonstrated using those ionic liquids.

• Applied Chemistry for Engineering
• /
• v.1 no.1
• /
• pp.23-29
• /
• 1990

The effect of a rapid freeze pretreatment of organic ion exchange resins on their grinding properties was studied. It was found that the structure of ion exchange resins was defected by freezing pressure formed in the process of rapid freezing. The defected resins didn't recover their own structure after thawing and those could be easy to be broken at room temperature by small force. Therefore, organic ion exchange resins could be ground readily at room temperature after rapid-freezing the fully swelled resins using by solid carbon dioxide, or liquid nitrogen. The rapid freeze pretreatment of cation exchange resins was very effective on grinding in particular. However, the effect of the pretreatment of anion exchange resins on grinding was less than that of cation exchange resins. In case of anion exchange resins, the ionic form of affected the grindability remarkably.

• 한국신재생에너지학회:학술대회논문집
• /
• 2009.06a
• /
• pp.24-27
• /
• 2009

Solid-state dye-sensitized solar cells (DSSCs) have been constructed employing supramolecular electrolytes with multiple hydrogen bonding. A supramolecule was facilely synthesized by one-pot reaction between the amines of methyl isocytosine (MIC) and the epoxy groups of poly(ethylene glycol diglycidyl ether) (PEGDGE) to produce quadruple hydrogen bonding units. Hydrogen bonding interactions and dissolution behavior of salt in supramolecular electrolytes are investigated. The ionic conductivity of the supramolecular electrolytes with ionic liquid, i.e. 1-methyl-3-propylimidazolium iodide (MPII) reaches $8.5{\times}10^{-5}$ S/cm at room temperature, which is higher than that with metal salt (KI). A worm-like morphology is observed in the FE-SEM micrographs of $TiO_2$ nanoporous layer, due to the connection of $TiO_2$ nanoparticles resulting from adequate coating by electrolytes. DSSCs employing the supramolecular electrolytes with MPII and KI exhibit an energy conversion efficiency of 2.5 % and 0.5 %, respectively, at 100 $mW/cm^2$, indicating the importance of the cation of salt. Solar cell performances were further improved up to 3.7 % upon introduction of poly(ethylene glycol dimethyl ether) (PEGDME) with 500 g/mol.

• Polymer(Korea)
• /
• v.33 no.6
• /
• pp.544-550
• /
• 2009

In this study, we have designed [Epoxy/PEG] polymer gel electrolyte systems by thermal curing the mixtures of epoxy, PEG, imidazole catalyst, and a plasticizer of 1:1 ethylene carbonate and propylene carbonate in the presence of $LiPF_6$ salt. In order to enhance the poor mechanical property of the Corresponding [Epoxy/PEG] gel electrolyte PVdF-HFP was incorporated into the system. The ionic conductivities of the polymer gel electrolytes were related to the amount of PVdF-HFP in blends as well as the amount of liquid electrolyte. The optimized gel system showed room-temperature conductivities of $2.56\times10^{-3}S/cm$.

• Journal of the Korean Electrochemical Society
• /
• v.15 no.4
• /
• pp.230-235
• /
• 2012

Polymer electrolytes consisted of $BF_3LiMA$ and 300 (PEGMA300) or 1100 (PEGMA1100) g $mol^{-1}$ of PEGMA were prepared and the electrochemical properties were characterized. Interestingly, the AC-impedance measurement shows $1.22{\times}10^{-5}S\;cm^{-1}$ of room temperature ionic conductivity from PEGMA1100 based solid polymer electrolytes while $8.54{\times}10^{-7}S\;cm^{-1}$ was observed in PEGMA300 based liquid polymer electrolytes. The more suitable coordination between lithium ion and ethylene oxide (EO) unit might be the reason of higher ionic conductivity which can be possible in PEGMA1100 based electrolytes since it has 23 EO units in monomer. The lithium ion transference number was found to be 0.6 due to the side reactions between $BF_3$ and lithium metal expecially for longer time but 0.9 was observed within 3000 seconds of measuring time which is strong evidence of a single-ion conductor.