• Journal of the Korean Ceramic Society
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• v.38 no.10
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• pp.894-900
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• 2001

The spinel $Li{Mn_2}{O_4}$ catalysts for $CO_2$ decomposition were synthesized by a sol-gel method using manganese acetate and lithium hydroxide as starting materials through drying at $150^{\circ}C$ for 12 hrs under oxygen atmosphere followed by heat treatment at $480^{\circ}C$ for 12 hrs. The synthesized $Li{Mn_2}{O_4}$ were reduced by hydrogen for 3 hrs at various temperatures and the decomposition rate of carbon dioxide was investigated at 300, 325, 350, 375 and $400^{\circ}C$ using the $Li{Mn_2}{O_4}$ reduced by hydrogen gases. As a result of experiment, the optimum temperature of hydrogen reduction and $CO_2$ decomposition was shown $350^{\circ}C$. The physicochemical properties of the spinel $Li{Mn_2}{O_4}$ the reduced $Li{Mn_2}{O_4}$ and the $Li{Mn_2}{O_4}$ after $CO_2$ decomposition were examined with XRD, SEM and TGA.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.10
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• pp.890-896
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• 2009

Li(Ni, Co, Mn)$O_2$ has been known as one of the most promising cathode materials for lithium secondary batteries. However, it has some problems to overcome for commercialization such as inferior rate capability and unstable thermal stability. In order to address these problems, surface modification of cathode materials by coating has been investigated. In the coating techniques, selection of coating material is a key factor of obtaining enhanced properties of cathode materials. In this work, we introduced solid electrolyte (Li-La-Ti-O) as a coating material on the surface of $Li[Ni_{0.3}Co_{0.4}Mn_{0.3}]O_2$ cathode. Specially, we focused on a rate performance of Li-La-Ti-O coated $Li[Ni_{0.3}Co_{0.4}Mn_{0.3}]O_2$ cathode. Both bare and Li-La-Ti-O 2 wt.% coated sample showed similar discharge capacity at 0.5C rate. However, as the increase of charge-discharge rate to 3C, the coated samples displayed better discharge capacity and cyclic performance than those of bare sample.

• Journal of the Korean Applied Science and Technology
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• v.18 no.3
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• pp.167-173
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• 2001

The spinel $LiMn_{2}O_{4}$ powders were synthesized at $480^{\circ}C$ for 12 h in air by a sol-gel method using manganese acetate and lithium hydroxide as starting material and the $Fe_{3}O_{4}$ powders were synthesized by the precipitation method using $0.2M-FeSO_{4}{\cdot}H_{2}O$ and 0.5M-NaOH. The synthesized $Fe_{3}O_{4}$ powders were mixed at portion of 5, 10, 15 and 20 wt% about $LiMn_{2}O_{4}$ powders through ball-milling followed by drying at room temperature for 48 h in air. The mixed catalysts were reduced at $350^{\circ}C$ for 3 h by hydrogen and the decomposition rate of carbon dioxide was measured at $350^{\circ}C$ using the reduced catalysts. As the results of $CO_{2}$ decomposition experiments, the decomposition rates of carbon dioxide were 85% in all catalysts but the initial decomposition rates of $CO_{2}$ were slightly high in the case of the $5%-Fe_{3}O_{4}$ added catalyst.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.64-65
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• 2008

3D microbattery에 사용할 수 있는 $LiMn_2O_4$ 3차원 박막전극을 제조하여 그 전기화학적 특성을 관찰하였다. 3차원 구조의 형성을 위하여 먼저 polystyrene(PS) microsphere를 platinum이 증착된 Si/$SiO_2$ 기판위에 dip-coating 방식으로 코팅시켜 template로 사용하였다. 그 위에 sol-gel법을 이용, 박막을 형성시킨 후 template 를 제거하는 방식으로 $LiMn_2O_4$ 3차원 박막전극을 형성하였는데 이때 solution은 Lithium acetylacetonate[$LiCH_3CO-CHCOCH_3$], Manganese(III) acetylacetonate [Mn$(CH_3COCHCOCH_3)_3$]를 source 물질로 1-butanol과 acetic acid를 solvent로 활용하여 제조하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.293-293
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• 2007

현재 활발하게 진행되고 있는 이차전지 양극 물질 중 저렴한 가격과 친환경성으로 각광받고 있는 $LiMn_2O_4$ spinel 산화물은 여러 장점에도 불구하고 용량 값이 기존 알려져 있던 Co-계 산화물에 비해 떨어지고 cycle 특성 역시 현저하게 이어진다. 이는 Mn이 전해액과의 반응에 있어 구조적인 안정성을 지니지 못하여 용출되어 나타나는 특성이다. 이번 연구에서는 Mn의 용출을 저지하고 용량의 향상을 이룰 수 있는 전이금속 중 Fe산화물을 치환하여 구조적 안정성을 갖도록 하였다. Fe산화물 치환을 통해 기본적 물성의 변화와 전기적 특성 변화를 측정하였고 공정에서의 온도 및 입도에 따른 영향도 확인하였다. Fe산화물은 Mn 자리의 3+와 4+의 자리에 치환되어 용량을 증대시키고 사이클 특성을 10회 기준으로 20%가량 향상시키는 효과를 가져왔다.

• Korean Journal of Crystallography
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• v.8 no.2
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• pp.149-153
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• 1997

ZnO varistor based on ZnO-Bi2O3-Co3O4-MnCO3-Cr2-O3-Sb2O3 system with Sb2O3 contents were studied for grain size variation and microstructure properties. The composition of pure ZnO varistor was observed composition was inhibited owing to formation of Zn7Sb2O12 spinel phase and did not observed abnrmal grain growth. With Sb2O3 contents, the grain sizes of ZnO varistor were remarkably decreased and the microstructure had the distribution of dense and homogeneous grains.

• 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.

• Journal of the Korean Electrochemical Society
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• v.10 no.1
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• pp.48-51
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• 2007

In order to investigate the effects of particle size and specific surface area(BET area) of spinel powder, $LiMn_2O_4$ were synthesized using metal oxide precursor by co-precipitation method(CoP) and solid state reaction (SSR) .X-ray diffraction(XRD) patterns revealed that the both prepared powder has a well developed spinel structure with Fd3m space group. The $LiMn_2O_4$ prepared by co-precipitation showed spherical morphology with narrow size distribution. However, the $LiMn_2O_4$ prepared by solid state reaction showed relatively smaller particles with irregular shape. The measured BET areas of the powers are $0.8m^2g^{-1}$ (CoP) and $3.6m^2g^{-1}$(SSR). The electrochemical performance of the Prepared $LiMn_2O_4$ powders was evaluated using coin type cells(CR2032) at elevated temperature ($55^{\circ}C$). The $LiMn_2O_4$ prepared by co-precipitation showed the better cycling performance(82.3%capacity retention at $50^{th}$ cycle) than that of the $LiMn_2O_4$(68.3%) prepared by solid state reaction at elevated temperature.

• Journal of the Korean Electrochemical Society
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• v.16 no.4
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• pp.191-197
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• 2013

The one of the cathode material, $Li(Ni_{0.5}Co_{0.2}Mn_{0.3})O_2$, was synthesized by the precursor, $Ni_{0.5}Co_{0.2}Mn_{0.3}(OH)_2$, from the co-precipitation method and the morphologies of the primary particle of precursors were flake and needle-shape by controlling the precipitation parameters. Identical powder properties, such as particle size, tap density, chemical composition, were obtained by same process of lithiation and heat-treatment. The relation between electrochemical performances of $Li(Ni_{0.5}Co_{0.2}Mn_{0.3})O_2$ and the primary particle morphology of precursors was analyzed by SEM, XRD and EELS. In the $Li(Ni_{0.5}Co_{0.2}Mn_{0.3})O_2$ cathode from the needle-shape precursor, the primary particle size was smaller than that from flake-shape precursor and high Li concentration at grain edge comparing grain center. The cycle and rate performances of the cathode from needle-shape precursor shows superior to those from flake-shape precursor, which might be attributed to low charge-transfer resistance by impedance measurement.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.12
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• pp.2263-2273
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• 2000

Catalytic wet air oxidation of acetic acid over Mn-Ce based catalysts deposited on various supports ($SiO_2$, $TiO_2$, $ZrO_2$), $ZrSiO_4$, $ZrO_2(10wt%)/TiO_2$) have been carried out in high pressure microreactors. Also, promotional effects by small addition(O.5~1.0 wt%) of p-type semiconductors (CoO, $Ag_2O$, SnO) have been investigated. From the screening tests for initial activity ranking, both Mn(2.8)-Ce(7.2 wt%) and Ru(O.4)Mn(2.7)-Ce(6.9 wt%) supported on $TiO_2$ were selected as the promising reference candidates. In $Mn-Ce/TiO_2$ reference catalyst, addition of small amount of each p-type semiconductor (Co, Sn and Ag) resulted in activity promotional effect and the degree of the increase was in the following order: Co> Ag > Sn. Especially, $Mn-Ce/TiO_2$ promoted with 0.5 wt% Co gave the 2.6 folds activity increase compared to the reference case attributing to the surface area increase as well as synergy effect. In $Ru-Mn-Ce/TiO_2$ reference catalyst, only Co(1.0 wt%) promoted case showed a little reaction rate increase.