• Journal of the Korean Electrochemical Society
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• v.17 no.3
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• pp.156-163
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• 2014

In this study, we tried to improve the cycling performance of lithium-ion batteries by suppressing decomposition of the electrolyte solution containing fluorsilane-based additive. Trifluoropropyltrimethoxysilane was electrochemically oxidized and reduced prior to the decomposition of the liquid electrolyte composed of lithium salt and carbonate-based organic solvent. Thus, the stable solid electrolyte interphase (SEI) layer on both negative electrode and positive electrode was formed, and it was confirmed that the cycling performance of lithium-ion batteries assembled with electrolyte solution containing 5 wt.% trifluoropropyltrimethoxysilane was the mostly enhanced. The products formed on electrodes were analyzed by the SEM and XPS analysis, and it was demonstrated that trifluoropropyltrimethoxysilane can be one of the promising SEI-forming additives.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2004.06a
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• pp.355-355
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• 2004

사용후핵연료 금속전환체는 세라믹형 사용후핵연료를 리튬용융염으로 금속전환하여 생성한 우라늄금속으로 상온에서도 표면산화가 진행될 정도로 매우 불안정한 상태이다. 이에 대한 저장 안정성 향상방안을 도출하기 위해 금속전환체의 주성분인 금속우라늄과 산화 안정화물질인 Nb을 첨가한 모의 금속전환체 합금을 제작하여 $200^{\circ}C~300^{\circ}C$ 온도구간에서 열중량분석기(TGA)를 이용해 순수 산소분위기로 산화시험을 수행하였다.(중략)

• Journal of Korean Society of Environmental Engineers
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• v.31 no.7
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• pp.505-514
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• 2009

Aqueous potassium salt of serine was proposed as an alternative $CO_2$ absorbent to monoethanolamine (MEA) and its $CO_2$ absorption characteristics were studied. The experiment has been conducted using screening test equipment with NDIR type gas analyzer and vapor-liquid equilibrium apparatus. $CO_2$ absorption/desorption rate and net amount of $CO_2$ absorbed in cyclic process are the criteria to assess the $CO_2$ absorption characteristics in this study. Effective $CO_2$ loading of potassium salt of serine and MEA are 0.425 and 0.230 respectively. Cyclic capacities are 0.354 and 0.298 for potassium salt of serine and MEA. The absorption rate of the potassium serinate decreased sharply at $CO_2$ loading is 0.1 and were maintained approximately at half of MEA. To enhance the absorption rate of aqueous potassium salt of serine, small quantities of rate promoters, namely piperazine and tetraethylenepentamine were blended, so that rich $CO_2$ loading were increased by 13.7% and 18.7% respectively. The rich $CO_2$ loading of potassium salt of serine was 29.2% and 35.0% higher than those of aqueous sodium and lithium salt of serine, respectively. The absorption rate of potassium salt of valine and isoleucine which have similar molecular structures to serine were lower than that of serine because of the presence of bulky side group. Precipitation phenomena during $CO_2$ absorption were discussed by the aid of literatures.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2003.11a
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• pp.447-452
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• 2003

We had clarified the reactions of the rare earth oxides($RE_2O_3$) with lithium oxide produced in lithium reduction process of oxide fuels. Oxides of scandium, yttrium, praseodymium, neodymium, samarium, europium, gadolinium, ytterbium and lutetium reacted with lithium oxide in the higher concentration than the respective certain critical concentration of lithium oxide and formed complex oxides($LiREO_2$). The critical lithium oxide concentrations for the formation of complex oxides of scandium, yttrium, praseodymium, neodymium, samarium, europium, gadolinium, ytterbium and lutetium oxide were respectively 0.1 wt%, 1.9 wt%, 5.3 wt%, 5.0 wt%, 3.0 wt%, 3.9 wt% 2.9 wt%, 2.6 wt% and 0.3 wt%. Cerium and lanthanum oxide did not react with lithium oxide. These complex oxides obtained from experiments have limited solubility in lithium chloride at $650^{\circ}C$.

• Journal of the Korean Electrochemical Society
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• v.14 no.2
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• pp.98-103
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• 2011

[ $Li[Ni_{0.8}Co_{0.15}Al_{0.05}]O_2$ ]cathode material for lithium secondary battery is obtained using co-precipitation method. To determine the optimal metal solution concentration value, the CSTR coprecipitation was carried out at various concentration values(1-2 mol/L). The surface morphology of coated samples was characterization by SEM(scanning electron microscope) and XRD (X-Ray Diffraction)analyses. Impedance analysis and cyclic voltammogram presented that internal resistance of the cell was dependent upon the concentration of metal solution. such data is very helpful in determining the optimal content of metal solution concentration to enhancing electrochemical property by adjusting powder size distribution and crystal structure.

• Polymer(Korea)
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• v.31 no.4
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• pp.297-301
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• 2007

In this work, polymer/(layered silicate) nanocomposites (PLSN) based on poly (ethylene oxide) (PEO), ethylene carbonate (EC) as a plasticizer, lithium salt ($LiClO_4$), and sodium montmorillonite ($Na^+-MMT$) or organic montmorillonite (organic MMT) clay were fabricated. And the effects of organic MMT on the polymer matrix were investigated as a function of ionic conductivity. For the application to electrolytes an Li batteries, polymer electrolytes containing the organic nanoclays were used in this work. As a result, the spacing between layers and hydrophobicity of the organic nanoclays were increased, affecting on the exfoliation behaviors of the MMT layers in clay/PEO nanocomposites. From ion-conductivity results, the organic-MMT showed higher values than those of $Na^+-MMT$, and the MMT-20A sample that was treated by methyl dihydrogenated tallow ammonium, showed the highest conductivity in this system.

• Korean Chemical Engineering Research
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• v.47 no.4
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• pp.476-480
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• 2009

A polymer composite electrolyte of a blend of poly(methyl methacrylate)(PMMA) and poly(ethylene oxide) (PEO) as a host polymer, the ethylene carbonate as a solvent, and $LiClO_4$ as a salt was studied. The crystallinity of the polymer electrolytes was evaluated using differential scanning calorimeter(DSC). The ionic conductivity of the polymer electrolytes was measured by frequency response analyzer(FRA) method. The effect of PEO/PMMA blend ratios on the ionic conduction in these electrolytes was investigated. The electrolyte films showed a phase separation due to immiscibility of the PMMA with the PEO. The PMMA-rich phase and the PEO-rich phase were produced during a film casting. The ionic conductivity of blend electrolyte was dependent on the content of PMMA and showed the highest value at 20 wt.%. However, when PMMA content exceeds 20 wt.%, the ionic conductivity was decreased due to the slow ionic transport through the PMMA-rich phase.

• Resources Recycling
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• v.11 no.3
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• pp.10-16
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• 2002

In the leaching of $LiCoO_2$with a strong acid such as sulfuric and nitric acid, an additional step was needed to recover cobalt and lithium separately from spent lithium ion batteries (LIBs). The leaching of $LiCoO_2$in an oxalic acid solution was investigated to recover cobalt selectively using a low solubility of cobalt oxalate at low pH. Leaching efficiency of 95% of lithium and less than 1% of cobalt were obtained when pure $LiCoO_2$powder was leached in 3M oxalic acid at $80^{\circ}C$ and 50 g/L pulpdensity. Under the above leaching conditions, complete dissolution of lithium was accomplished with mere 0.25% of cobalt in the solution when the cathodic active material collected from spent LIBs was employed. The lithium in the leaching solution can be recovered as a form of carbonate or hydroxide depending on the addition of $Na_2$$CO_3$or LiOH.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.32 no.2
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• pp.61-67
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• 2022

A metal salt solution was prepared from valuable metals (Ni, Co, Mn) recovered from a scrap of waste lithium secondary batteries, and an NCM811 precursor was synthesized from the solution. The effect on precursor formation according to reaction time was confirmed by SEM, PSA, and ICP analysis. Based on the analysis results, the electrochemical properties of the synthesized NCM811 precursor and the commercial NCM811 precursor were investigated. The Galvano charge-discharge cycle, rate performance, and Cycle performance were compared, and as a result, there was no significant difference from commercial precursors.

• Journal of the Korean Electrochemical Society
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• v.7 no.4
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• pp.183-188
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• 2004

In order to develop polymer electrolyte for lithium/sulfur batteries, highly microporous P(VdF-HFP) membranes were prepared by phase inversion method. Porous structure was controlled by extracting NMP with mixture of deionized water and methanol. Porous structure of the membranes was observed with SEM. Polymer electrolytes were prepared by soaking the porous membranes in 1M $LiCF_3SO_3-TEGDME/EC$. The ionic conductivity of polymer electrolyte was found to be at high as $2\times10^{-3}S/cm$ when the polymer membrane extracted by $80\%$ methanol was used. The microporous polymer electrolyte optimized in this work displayed high ionic conductivity, uniform pore size, low interfacial resistance and stable ionic conductivity with storage time. The ionic conductivity of polymer electrolytes was measured with various lithium salts, and the conductivity showed $3.3\times10^{-3}S/cm$ at room temperature when $LiPF_6$ was used as a lithium salt.