• 한국표면공학회지
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• 제51권4호
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• pp.243-248
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• 2018

All solid state thin film batteries with two types of cell structure, Pt / $LiCoO_2$ / LiPON / Cu and Pt / $LiCoO_2$ / LiPON / $LiCoO_2$ / Cu, are prepared and their electrochemical performances are investigated to evaluate the effect of $LiCoO_2$ interlayer at the interface of LiPON / Cu. The crystallinity of the deposited $LiCoO_2$ thin films is confirmed by XRD and Raman analysis. The crystalline $LiCoO_2$ cathode thin film is obtained and $LiCoO_2$ as the interlayer appears to be amorphous. The surface morphology of Cu current collector after cycling of the batteries is observed by AFM. The presence of a 10 nm-thick layer of $LiCoO_2$ at the interface of LiPON / Cu enhances the interfacial adhesion and reduces the interfacial resistance. As a result, Li plating / stripping at the interface of LiPON / Cu during charge/discharge reaction takes place more uniformly on Cu current collector, while without the interlayer of $LiCoO_2$ at the interface of LiPON / Cu, the Li plating / stripping is localized on current collector. The thin film batteries with the interlayer of $LiCoO_2$ at the interface of LiPON / Cu exhibits enhanced initial coulombic efficiency, reversible capacity and cycling stability. The thickness of the anode current collector Cu also appears to be crucial for electrochemical performances of all solid state thin film batteries.

• 한국분말재료학회지
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• 제23권1호
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• pp.33-37
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• 2016

10 wt.% and 20 wt.%$Li-TiO_2$ composite powders are synthesized by a sol-gel method using titanium isopropoxide and $Li_2CO_3$ as precursors. The as-received amorphous 10 wt.%$Li-TiO_2$ composite powders crystallize into the anatase-type crystal structure upon calcination at $450^{\circ}C$, which then changes to the rutile phase at $750^{\circ}C$. The asreceived 20 wt%$Li-TiO_2$ composite powders, on the other hand, crystallize into the anatase-type structure. As the calcination temperature increases, the anatase $TiO_2$ phase gets transformed to the $LiTiO_2$ phase. The peaks for the samples obtained after calcination at $900^{\circ}C$ mainly exhibit the $LiTiO_2$ and $Li_2TiO_3$ phases. For a comparison of the photocatalytic activity, 10 wt.% and 20 wt.% $Li-TiO_2$ composite powders calcined at $450^{\circ}C$, $600^{\circ}C$, and $750^{\circ}C$ are used. The 20 wt.%$Li-TiO_2$ composite powders calcined at $600^{\circ}C$ show excellent efficiency for the removal of methylorange.

• Bulletin of the Korean Chemical Society
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• 제32권10호
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• pp.3682-3686
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• 2011

The electrochemical properties of lithium-sulfur batteries with binary electrolytes based on DME and DOL, TEGDME and DOL mixed solvent containing $LiClO_4$, LiTFSI, and LiTF salts were investigated. The ionic conductivity of 1M LiTFSI and $LiClO_4$ electrolytes based on TEGDME and DOL increased as the volume ratio of DOL solvent increased, because DOL effectively reduces the viscosity of the above electrolytes medium under the same salts concentration. The first discharge capacity of lithium-sulfur batteries in the DME and DOL-based electrolyte followed this order: LiTFSI (1,000 mAh/g) > LiTF (850 mAh/g) > $LiClO_4$ (750 mAh/g). In case of the electrolyte based on TEGDME and DOL, the first discharge capacity of batteries followed this order: $LiClO_4$ (1,030 mAh/g) > LiTF (770 mAh/g) > LiTFSI (750 mAh/g). The cyclic efficiency of lithium-sulfur batteries at 1M $LiClO_4$ electrolytes is higher than that of batteries at other lithium salts-based electrolytes. Lithium-sulfur battery showed discharge capacity of 550 mAh/g until 20 cycles at all electrolytes based on DME and DOL solvent. By contrast, the discharge capacity of batteries was about 450 mAh/g at 1M LiTFSI and LiTF electrolytes based on TEGDME and DOL solvent after 20 cycles.

• 대한전자공학회논문지
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• 제4권2호
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• pp.16-21
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• 1967

이 보고는 처음에 Li drifted Ge 검출기에 관해서 이 Li drifted Ge 검출기에 의한 열중성자로부터의 Cl(n, r) 반응에서 생기는 r선 스텍트로를 보여준다. 이 Li drifted Ge 검출기의 에너지 분해능은 의 122KeV에서 4.5KeV, 의 1333KeV에서 10KeV이다.

• 한국결정성장학회지
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• 제6권2호
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• pp.166-176
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• 1996

새로운 비선형 광학결정으로 유망시되는 $CsLiB_{6}O_{10}$ 결정을 육성하기 위한 기초 조건을 조사하였다. 화학양론적으로 혼합된 $CsLiB_{6}O_{10}$ 조성으로부터 $600^{\circ}C$ 이상의 온도에서 같은 조성의 결정이 형성되었고, 이 결정은 $800^{\circ}C$까지 상변화를 나타내지 않았으며, $850^{\circ}C$에서 합치용융하였다. $CsLiB_{6}O_{10}$ 조성을 용융시킨 뒤, 융액을 $1~150^{\circ}C/hr$의 냉각 속도로 냉각시키면, 냉각 속도에 관계없이 유리가 생성되었다. 그러나 융액중에 $CsLiB_{6}O_{10}$ 결정 seed가 존재하는 경우에는 융액으로부터 $CsLiB_{6}O_{10}$ 결정이 직접 석출되었다. Seed 결정을 이용하여 온도 구배가 $100^{\circ}C/cm$인 일방향 전기로에서 0.06 mm/hr의 응고 속도로 투명한 $CsLiB_{6}O_{10}$ 단결정을 육성하였다. 육성된 결정의 구조 해석 결과, 이결정은 noncentrosymmetric tetragonal space group 142d에 속하고, unit cell dimensions은 $a=10.467(1)\;{\AA},\;c=8.972(1)\;{\AA}과\;V=983.0(2)\;{\AA}^3$이었다. 이 결정의 광학적 특성은 180mm에서 absorption edge를 가지고 300 nm이상의 파장 영역에서 70%의 광투과율(두께 0.5 mm)을 나타내었다.

• 방사성폐기물학회지
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• 제10권4호
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• pp.229-236
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• 2012

$Li_2O$-LiCl 용융염을 이용한 전해환원기술은 사용후핵연료로부터 우라늄 금속을 회수하기 위해 연구되고 있다. 이 전해환원기술에서는 $Li_2O$가 촉매로 이용되기 때문에 그 농도를 유지하는 것은 매우 중요한 운전인자이다. $ZrO_2$는 피복관의 주성분이 Zr이기 때문에 사용후핵연료에 불가피하게 함유되며, 본 연구에서는 $Li_2O$를 촉매로 이용하는 전해환원공정에서 $ZrO_2$의 거동을 살펴보았다. $Li_2O$와 $ZrO_2$의 화학반응과 전해환원공정 중에서의 생성물을 분석한 결과, $Li_2ZrO_3$와 $Li_4ZrO_4$가 주요하게 관찰되었고, 이는 $Li_2O$의 손실을 가져오는 원인이 된다. 즉, $ZrO_2$는 $Li_2O$를 소모하는 역할을 하며, 반응생성물은 전기화학적으로 안정하기 때문에 $Li_2O$의 손실이 불가피하게 된다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1998년도 추계학술대회 논문집
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• pp.121-124
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• 1998

The purpose of this study is to research and develop solid polymer electrolyte(SPE) for Li secondary battery. This paper describes temperature dependence of conductivity, impedance spectroscopy, electrochemical properties of PVDF electrolytes as a function of a mixed ratio. Polyvinylidene(PVDF) based polymer electrolyte films were prepared by thermal gellification method of preweighed PVDF, plasticizer and Li salt. The conductivity of PVDF electrolytes was 10$\^$-3/S/cm. 25PVDFPC$\_$10/EC$\_$10/LiClO$_4$ electrolyte shows the better conductivity of the others. 25PVDFPC$\_$10/EC$\_$10/LiClO$_4$electrolyte remains stable up to 4.7V vs. Li/Li$\^$+/. Steady state current method and ac impedance used for the determination of transference numbers in PVDFD electrolyte film. The transference number of 25PVDFPC$\_$10/EC$\_$10/LiClO$_4$electrolyte is 0.58.

• 한국세라믹학회지
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• 제41권5호
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• pp.388-394
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• 2004

균일하게 혼합된 LiNO$_3$와 Co 금속분말을 알곤 분위기 하에서 SHS 공정으로 리튬이차전지용 양극활물질인 LiCoO$_2$분말을 합성하였다. 여러 가지 반응변수에 따라 제조된 분말의 특성과 전기화학적 특성평가를 수행하였는데, 반응온도 및 속도와 제조된 분말의 입도는 각각 Li/Co 몰비와 시료의 냉각속도 변화로 제어 가능하였다. Li/Co 몰비가 1.05일 때 최대방전용량인 145 mAh/g을 나타냈으며, 10회 충ㆍ방전 실험 후 6.4%의 낮은 용량감소를 갖는 비교적 안정된 cycling 특성을 보였다.

• Bulletin of the Korean Chemical Society
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• 제32권3호
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• pp.836-840
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• 2011

This study examines the effects of a carbon coating on the electrochemical performances of $LiFePO_4$. The results show that the capacity of bare $LiFePO_4$ decreased sharply, whereas the $LiFePO_4$/C shows a well maintained initial capacity. The Li ion diffusivity of the bare and carbon coated $LiFePO_4$ is calculated using cyclic voltammetry (CV) to determine the correlation between the electrochemical performance of $LiFePO_4$ and Li diffusion. The diffusion constants for $LiFePO_4$ and $LiFePO_4$/C measured from CV are $6.56{\times}10^{-16}$ and $2.48{\times}10^{-15}\;cm^2\;s^{-1}$, respectively, indicating considerable increases in diffusivity after modifications. The Li ion diffusivity (DLi) values as a function of the lithium content in the cathode are estimated by electrochemical impedance spectroscopy (EIS). The effects of the carbon coating as well as the mechanisms for the improved electrochemical performances after modification are discussed based on the diffusivity data.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 추계학술대회 초록집
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• pp.137.2-137.2
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• 2011

Poly (sodium 4-styrenesulfonate) (PSS) is ionomer based on polystyrene that is electrical conductivity and isoviscosity. LiFePO4 has been a promising electrode material however its poor conductivity limits practical application. To enhance the electronic conductivity of LiFePO4, in this study we prepared LiFePO4- PSS composite by the hydrothermal method. LiFePO4 was heated at $170^{\circ}C$ for 12h and then different wt% PSS (0%, 2.91%, 4.75%, 7.36%, 10%) are added to LiFePO4 and milled at 300rpm for 10h. And then the obtained powders were subsequently heated at $500^{\circ}C$ for 1h under argon flow. The cathode electrode were made from mixtures of LiFePO4-PSS: SP-270- PVDF in a weighting ratio 75%: 25%:5%. The electrochemical properties of LiFePO4- PSS/Li batteries were analyzed by cyclic voltammetry and charge/discharge tests. LiFePO4-C/Li battery with 4.75 wt% PSS displays discharge capacity of 128 mAh g-1 at room temperature that is considerably higher than pure LiFePO4/Li battery ( 113.48 mAhg-1).