• Korean Journal of Materials Research
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• v.20 no.12
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• pp.669-675
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• 2010

One of the greatest challenges for our society is providing powerful electrochemical energy conversion and storage devices. Rechargeable lithium-ion batteries and fuel cells are among the most promising candidates in terms of energy and power density. As the starting material, $TiCl_4{\cdot}YCl_3$ solution and dispersing agent (HCP) were mixed and synthesized using ammonia as the precipitation agent, in order to prepare the nano size Y doped spherical $TiO_2$ precursor. Then, the $Li_4Ti_5O_{12}$ was synthesized using solid state reaction method through the stoichiometric mixture of Y doped spherical $TiO_2$ precursor and LiOH. The Ti mole increased the concentration of the spherical particle size due to the addition of HPC with a similar particle size distribution in a well in which $Li_4Ti_5O_{12}$ spherical particles could be obtained. The optimal synthesis conditions and the molar ratio of the Ti 0.05 mol reaction at $50^{\circ}C$ for 30 minutes and at $850^{\circ}C$ for 6 hours heat treatment time were optimized. $Li_4Ti_5O_{12}$ was prepared by the above conditions as a working electrode after generating the Coin cell; then, electrochemical properties were evaluated when the voltage range of 1.5V was flat, the initial capacity was 141 mAh/g, and cycle retention rate was 86%; also, redox reactions between 1.5 and 1.7V, which arose from the insertion and deintercalation of 0.005 mole of Y doping is not a case of doping because the C-rate characteristics were significantly better.

• Applied Chemistry for Engineering
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• v.10 no.1
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• pp.73-79
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• 1999

The superstructured $Li_{4/3}Ti_{5/3}O_4$ was prepared by sol-gel process using a mixed solution of lithium acetate (LA) and titanium n-butoxide (TNB). The gel phase was obtained by adding ammonia water ($NH_4OH/TNB$ mole ratio of 0.35) and water ($H_2O/TNH$ mole ratio of 3.5) into the clear sol that was prepared after mixing TNB/LA mole ratio of 5/4 with AA/TNB mole raio of 0.125. It was found that the most suitable $Li_{4/3}Ti_{5/3}O_4$ was obtained by heat treatment of xerogel at $600^{\circ}C$ for 30 hrs. The synthesized $Li_{4/3}Ti_{5/3}O_4$ showed an initial discharge capacity of 174 mAh/g and the capacity loss of about 27.3% during 25 cycles in Li/1M $LiClO_4(in\;PC)/Li_{4/3}Ti_{5/3}O_4$ at current density of $0.15mA/cm^2$ and the voltage range of 0.5~3.0 V.

• Journal of the Korean Chemical Society
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• v.32 no.1
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• pp.65-70
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• 1988

Synthesis and biological activity test are described for the (Z)-9-tetradecen-1-yl acetate(1) and (Z)-11-tetradecen-1-yl acetate(1) and (Z)-11-tetradecen-1-yl acetate(2), the sex pheromone of the summer fruit tortrix moth, Adoxophyes orana. 8-Bromoctan-l-ol THP ether was prepared from 8-bromoctan-l-ol. The lithium anion of 1-hexyne was alkylated with 8-bromoctan-l-ol THP ether gave 9-tetradecyn-l-ol THP ether. Catalytic hydrogenation over Pd/BaSO4 followed by deprotection afforded (Z)-9-tetradecen-l-ol. Acetylation gave (Z)-9-tetradecen-1-yl acetate(1). l0-Bromodecan-l-ol THP ether was obtained from l0-bromodecan-l-ol. In liquid ammonia with THF and HMPA as cosolvents, sodium acetylide could be alkylated with 10-bromodecan-l-ol THP ether to give 11-dodecyn-l-ol THP ether. 11-Dodecyn-l-ol THP ether was then treated with n-BuLi in THF to give the lithium acetylide, which was alkylated with bromoethane to afford 11-tetradecyn-l-ol THP ether. Catalytic hydrogenation, deprotection, and acetylative gave (Z)-11-tetradecen-1-yl acetate(2). The synthetic pheromone thus obtained was attractive to the males of the summer fruit tortrix in the field.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.259-259
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• 2007

층상구조의 전이금속 산화물($LiMO_2$, M=Co, Ni, Mn)은 리튬이차전지용 양극재료로 활발한 연구가 진행되고 있다. 차세대 리튬이차전지 시스템의 개발 및 고성능화를 위해서는 전지의 용량을 결정하는 핵심 부품인 양극재료의 고용량화 및 고안정화는 필수 불가결하다. 따라서 본 연구에서는 상업적으로 큰 장점이 있는 고상반응 공정을 이용하여 리튬이차전지용 양극소재를 제조하고, 소재의 전기화학적, 구조적인 특성을 평가하였으며, 다음과 같은 주제를 가지고 연구를 진행하였다. $LiCoO_2$ 양극재료는 리튬이온전지로 널리 사용되고 있다. 높은 에너지 밀도의 리튬이온전지를 얻기 위해서는 $LiCoO_2$ 양극재료가 고용량화 및 고밀도화를 가져야 한다. 여기서 $LiCoO_2$ 분말이 irregular particle morphology를 가지면 tap density가 $2.2-2.4gcm^{-3}$로 에너지 밀도가 낮으나, 구형 $LiCoO_2$의 정극재료는 tap density가 $2.6-2.8gcm^{-3}$로 상대적으로 energy density가 높아지는 효과가 있다. 구형 $LiCoO_2$ 양극재료를 합성하기 위해서는 chelating agent를 이용한 "controlled crystallization" 침전법을 사용하여 합성한 구형 코발트 수화물을 사용하고 있다. "controlled crystallization" 침전법에서 사용되는 chelating agent로는 주로 ammonia가 이용되고 있다. 본 연구에서는 chelating agent로 ethylene diamine을 사용하여 sodium hydroxides를 precipitation으로 침전 반응하여 구형 코발트 수화물을 합성하였다. 상기 방법으로 합성된 코발트 수화물과 리튬 수화물($LiOH{\cdot}H_2O$-고순도화학(高殉道化學))을 사용하여 고상법을 통하여 $LiCoO_2$를 합성하였다. 제조된 분말의 결정구조와 전기화학적 특성분석은 X-선 회절분석 및 리트벨트 구조정산, 그리고 충/방전 싸이클링을 수행하였으며, 분말의 미세구조 변화를 SEM을 이용하여 분석하였다.

• Journal of the Korean Chemical Society
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• v.31 no.6
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• pp.576-581
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• 1987

Synthesis and Biological activity test are described for the (E)-11-tetradecen-1-yl acetate and (Z)-11-tetradecen-1-yl acetate, the sex pheromone of the Asiatic leafroller moth (Archippus breviplicanus Walsingham). 10-Bromodecan-1-ol THP ether was prepared from 10-bromodecan-1-ol. In liquid ammonia with THF and HMPA as cosolvents, sodium acetylide could be alkylated with 10-bromodecan-1-al THP ether to give 11-dodecyn-1-ol THP ether. 11-Dodecyn-1-ol THP ether was then treated with n-Buli in THF to give the lithium acetylide, which was alkylated with bromoethane to afford 11-tetradecyn-1-ol THP ether. 11-Tetradecyn-1-ol THP ether was then reduced over $Pd/BaSO_4$ and with Na in liquid $NH_3$ to give (Z)-11-tetradecen-1-ol THP ether and (E)-11-tetradecen-1-ol THP ether, respectively. (Z)-and (E)-11-Tetradecen-1-ol THP ether thus obtained were deprotected by refluxing in the presence of PPTS and ethanol. (Z)-and (E)-11-tetradecen-1-ol were acetylated with acetic anhydride to afford the final products, (Z)-11-tetradecen-1-yl acetate (1) and (E)-11-tetradecen-1-yl acetate (2), respectively. The synthetic pheromone thus obtained was attractive to the males of the Asiatic leafroller moth in the field.