• Korean Journal of Metals and Materials
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• v.49 no.2
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• pp.174-179
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• 2011

We investigated the surface morphology changes of a lithium/sulfur battery using multi-walled canbon nanotube added sulfur electrode during charge-discharge cycling. The Li/S cell showed the first discharge capacity of 1286 mAh/g-S, which utilized is 71% of the theoretical value. It decreased to 328 mAh/g-S at the 100th cycle, which corresponds to about 19% utilization of the total sulfur in the cathode. The spherical lumps of the reaction product were observed on the surface of the sulfur electrode. This material was verified as lithium sulfide by X-ray diffraction measurement. The pores in the separator were filled with reaction product. Thus the diffusion of the $Li^+$ ion decreased, which resulted in the decreased capacity of the Li/S cell.

• Korean Journal of Metals and Materials
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• v.48 no.3
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• pp.262-267
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• 2010

$LiNi_{1-x}Mg_xO_2$(x=0, 0.025, 0.05, 0.075, 0.1) samples were synthesized by the solid-state reaction method. The crystal structure was analyzed by X-ray powder diffraction and Rietveld refinement. $LiNi_{1-x}Mg_xO_2$samples give single phases of hexagonal layered structures with a space group of R-3m. The calculated cation-anion distances and angles from the Rietveld refinement were changed with Mg contents in $LiNi_{1-x}Mg_xO_2$. The thicknesses of $NiO_2$ slabs were increased and the distances between the $NiO_2$ slabs were decreased with the increase in Mg contents in the samples. The electrical conductivities of sintered $LiNi_{1-x}Mg_xO_2$ samples were around $10^{-2}$ S/cm at room temperature. The electrochemical performances of $LiNi_{1-x}Mg_xO_2$were evaluated by coin cell test. Compared to $LiNiO_2$, $LiNi_{0.95}Mg_{0.05}O_2$ exhibited improved high-rate capability and cyclability due to the well-ordered layered structure by doping of Mg ion.

• Resources Recycling
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• v.21 no.2
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• pp.3-8
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• 2012

In the points of the environmental conservation and the recirculating utilization of limited resources, it is very important to recover valuable metals like Au, Ag, Pd, Cu, Sn, Ni, Co, and Li used as industrial raw materials from urban ores. From now, many processes have been developed for recovering the valuable metals contained in urban ores and some of them have been operated commercially. In the paper, pyrometallurgical processes developed for reclaiming valuable metals from urban ores will be briefly introduced.

• Journal of the Korean Ceramic Society
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• v.37 no.5
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• pp.466-472
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• 2000

As cathode materials of LiMn2O4-based lithium-ion secondary batteries, Li(Mn1-$\delta$M$\delta$)2O4 (M=Ni and Co, $\delta$=0, 0.05, 0.1 and 0.2) materials which Co and Ni are substituted for Mn, were syntehsized by the solid state reaction at 80$0^{\circ}C$ for 48 hours. No second phases were formed in Li(Mn1-$\delta$M$\delta$)2O4 system with substitution of Co. However, substitution of Ni caued to form a second phase of NiO when its composition exceeded over 0.2 of $\delta$ in Li(Mn1-$\delta$M$\delta$)2O4. As the results of charging-discharging test, the maximum capacity of Li(Mn1-$\delta$M$\delta$)2O4 appeared in $\delta$=0.1 for both Co and Ni. Also, Li(Mn1-$\delta$M$\delta$)2O4 electrode showed higher capacity and better cycle performance than LiMn2O4.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.452-452
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• 2009

HEV용 리튬 이차전지의 양극물질로서 $LiMn_2O_4$는 일반적으로 사용되고 있는 $LiCoO_2$에 비해 값이 저렴하고 독성이 낮으며, 높은 전압과 좋은 율 특성을 갖는 물질이다. 하지만 고온에서 전이금속인 Mn이 전해액으로 용출되어 급격한 용량감소로 인한 짧은 수명의 단점을 가지고 있다. 흔히 전구체로 쓰이는 $MnO_2$, $Mn_3O_4$, MnOOH등은 전기 분해법을 이용한 EMD가 주로 이용된다. 본 연구에서는 출발 물질로 $KMnO_4$와 $Mn(NO_3)_2$를 수용액 반응을 시켜서 농도, 온도변화에 따른 입자 형상 및 크기와 결정상의 변화를 관찰하고, 화학적 방법으로 얻어진 $MnO_2$와 LiOH를 합성하여 각각의 $LiMn_2O_4$를 비교 분석하고자한다.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.26-26
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• 2003

Lithium storage electrodes for rechargeable batteries require mixed electronic-ionic conduction at the particle scale in order to deliver desired energy density and power density characteristics at the device level. Recently, lithium transition metal phosphates of olivine and Nasicon structure type have become of great interest as storage cathodes for rechargeable lithium batteries due to their high energy density, low raw materials cost, environmental friendliness, and safety. However, the transport properties of this family of compounds, and especially the electronic conductivity, have not generally been adequate for practical applications. Recent work in the model olivine LiFePO$_4$, showed that control of cation stoichiometry and aliovalent doping results in electronic conductivity exceeding 10$^{-2}$ S/cm, in contrast to ~10$^{-9}$ S/cm for high purity undoped LiFePO$_4$. The increase in conductivity combined with particle size refinement upon doping allows current rates of >6 A/g to be utilized while retaining a majority of the ion storage capacity. These properties are of much practical interest for high power applications such as hybrid electric vehicles. The defect mechanism controlling electronic conductivity, and understanding of the microscopic mechanism of lithiation and delithiation obtained from combined electrochemical and microanalytical techniques, will be discussed

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2012.03a
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• pp.110-110
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• 2012

아라미드 섬유소재는 고강도, 고내열성의 소재로 다양한 용도전개가 가능하나, 일광 및 부식에 의한 내광성 및 내후성이 급격하게 저하되는 단점이 있다. 자외선의 광화학적 작용에 의해 변퇴, 경화, 취하, 강도저하가 일어나는 단점을 보완하기 위해 내광성 및 내화학성이 우수한 전이금속산화물 소재와의 복합화를 통해 내광성 및 내화학성 개선에 대하여 연구하였다. zinc acetate 수화물과 수산화리튬을 무수에탄올로 용해시킨 용액을 강하게 교반하여 나노 산화아연 졸을 제조하였다. 제조된 나노크기의 zinc oxide 입자의 형상과 입자분포 등 제조특성을 입도분석기, FE-SEM 및 EDS 분석을 통하여 고찰하였으며, 제조된 나노졸을 아라미드 섬유에 침지시켜 Xenon-arc 내후성시험기에서 80시간 동안 노출시켜 노출시간에 따른 물성변화를 분석하였다. 나노졸을 5~20% 픽업으로 패딩한 후 광에 노출된 아라미드의 인장강도는 나노졸을 처리하지 않은 아라미드 섬유보다 20~30% 개선된 인장강도를 나타내었다.

• Korean Journal of Environmental Agriculture
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• v.13 no.2
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• pp.191-198
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• 1994

2-Thiophenyltriisopropoxytitanium was prepared in situ by trans-metallization of 2-thiophenyllithium and chlorotitaniumtriisopropoxide. It could be isolated at room temperature and preserved at $-10{\circ}C$ for weeks. The reactivity of 2-thiophenyltriisopropoxytitanium to carbonyl compounds proved to be high. Complete aldehyde-selectivity was observed in competition reactions of 2-thiophenyl-triiso-propoxytitanium with a 1 : 1 mixture of aldehyde and ketone. In the competitive reaction of 2-thiophenyl-triisopropoxytitanium to ketone-ester function, ketone adduct was perfectly obtained.

• Journal of Powder Materials
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• v.21 no.2
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• pp.131-136
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• 2014

Cathode materials and their precursors are prepared with transition metal solutions recycled from the the waste lithium-ion batteries containing NCM (nickel-cobalt-manganese) cathodes by a $H_2$ and C-reduction process. The recycled transition metal sulfate solutions are used in a co-precipitation process in a CSTR reactor to obtain the transition metal hydroxide. The NCM cathode materials (Ni:Mn:Co=5:3:2) are prepared from the transition metal hydroxide by calcining with lithium carbonate. X-ray diffraction and scanning electron microscopy analyses show that the cathode material has a layered structure and particle size of about 10 ${\mu}m$. The cathode materials also exhibited a capacity of about 160 mAh/g with a retention rate of 93~96% after 100 cycles.

• Journal of the Korean Chemical Society
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• v.30 no.3
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• pp.327-332
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• 1986

Spatial (radial and height) distribution of electron number density is measured for an inductively coupled plasma under five operating conditions: (1) no carrier gas, (2) carrier gas without aerosel, (3) carrier gas with aerosol, (4) carrier gas with desolvated aerosol, and (5) carrier gas with aerosol and excess lithium. A complete RF power mapping of electron density is obtained. The plasma electrons for a typical analytical torch are observed to be hollow at the radial center in the region close to the induction coil, but diffuse rapidly toward the center in the higher region of the plasma. The presence of excess Li makes no significant change in the electron density profiles. The increases in the RF power levels increase the values of electron density uniformly across the radial coordinate.