• 한국전기화학회:학술대회논문집
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• 2005.04a
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• pp.53-53
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• 2005

• Proceedings of the Korean Nuclear Society Conference
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• 2001.10a
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• pp.277.2-277
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• 2001

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 1998.05a
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• pp.112-112
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• 1998

• Journal of the Korean Electrochemical Society
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• v.2 no.3
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• pp.156-162
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• 1999

Various types of iron oxide based materials as a cathode of lithium secondary battery have been prepared and their electrochemical characteristics have been also observed. In order to understand the fundamental characteristics of iron oxide electrode, three kinds of iron oxides such as iron oxides formed by direct oxidation of iron plate or iron powders and FeOOH powders were tested with cyclic voltammetry. The oxidation and reduction peaks due to the reaction of intercalation and deintercalation were not observed for the iron oxide prepared with iron plate and FeOOH powders. In case of iron oxide prepared from iron powders, only one reduction peak was observed. A layered form of $LiFeO_2$ was synthesized directly from $FeCl_3\cdot6H_2O,\;NaOH\;and\;LiOH$ and LiOH by hydrothermal reaction. The effect of NaOH on the electrode performance was examined. When increasing NaOH, it provides the electrode with less discharge capacity and efficiency, however, decreasing rate of discharge capacity became smaller. $LiFeO_2$ synthesized with the molar ratio of $NaOH/FeCl_3/LiOH$, 2/1/7 showed the largest capacity, but the discharging efficiency was sharply decreased after 30 cycles.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.340-341
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• 2005

Lithium titanium oxide as anode material for energy storage prepared by novel synthesis method. $Li_4Ti_5O_{12}$ based spinel-framework structures are of great interest material for lithium-ion batteries. We describe here $Li_4Ti_5O_{12}$ a zero-strain insertion material was prepared by novel sol-gel method and by high energy ball milling (HEBM) of precursor to from nanocrystalline phases. According to the X-ray diffraction and scanning electron microscopy analysis, uniformly distributed $Li_4Ti_5O_{12}$ particles with grain sizes of 100nm were synthesized. Lithium cells, consisting of $Li_4Ti_5O_{12}$ anode and lithium cathode showed the 173 mAh/g in the range of 1.0 $\sim$ 3.0 V. Furthermore, the crystalline structure of $Li_4Ti_5O_{12}$ didn't transfer during the lithium intercalation and deintercalation process.

• Journal of Electrochemical Science and Technology
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• v.1 no.1
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• pp.57-62
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• 2010

The lithium ion concentration dependant ionic conductivity and thermal properties of poly(ethylene glycol) methyl ether methacrylate (PEGMA)/acrylonitrile-based copolymer electrolytes with $LiClO_4$ have been studied by differential scanning calorimetry (DSC), linear sweep voltammetry (LSV) and AC complex impedance measurements. In systems with 11 wt% of acrylonitrile all liquid electrolytes were obtained regardless of lithium ion concentration. Complex impedance measurements with stainless steel electrodes give ambient ionic conductivities $8.1\times10^{-6}\sim1.4\times10^{-4}S cm^{-1}$. On the other hand, a hard and soft films at ambient temperature were obtained in copolymer electrolyte system consists of 15 wt% acrylonitrile with 6 : 1 and 3 : 1 of [EO] : [Li] ratio, respectively. DSC measurements indicate the crystalline melting temperature of poly(PEGMA) disappeared completely after addition of $LiClO_4$ in this system due to the complex formation between ethylene oxide (EO) unit and lithium salt. As a result, free standing film with room temperature ionic conductivity of $1.7\times10^{-4}S cm^{-1}$ and high electrochemical stability up to 5.5V was obtained by controlling of acrylonitrile and lithium salt concentration.

• Bulletin of the Korean Chemical Society
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• v.16 no.5
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• pp.416-421
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• 1995

The approximate rates and stoichiometry of the reaction of excess lithium gallium hydride with selected organic compounds containing representative functional groups were examined under the standard conditions (diethyl ether, 0 $^{\circ}C)$ in order to compare its reducing characteristics with lithium aluminum hydride and lithium borohydride previously reported, and enlarge the scope of its applicability as a reducing agent. Alcohols, phenol, and amines evolve hydrogen rapidly and quantitatively. However lithium gallium hydride reacts with only one active hydrogen of primary amine. Aldehydes and ketones of diverse structure are rapidly reduced to the corresponding alcohols. Conjugated aldehyde and ketone such as cinnamaldehyde and methyl vinyl ketone are rapidly reduced to the corresponding saturated alcohols. p-Benzoquinone is mainly reduces to hydroquinone. Caproic acid and benzoic acid liberate hydrogen rapidly and quantitatively, but reduction proceeds slowly. The acid chlorides and esters tested are all rapidly reduced to the corresponding alcohols. Alkyl halides and epoxides are reduced rapidly with an uptake of 1 equiv of hydride. Styrene oxide is reduced to give 1-phenylethanol quantitatively. Primary amides are reduced slowly. Benzonitrile consumes 2.0 equiv of hydride rapidly, whereas capronitrile is reduced slowly. Nitro compounds consumed 2.9 equiv of hydride, of which 1.9 equiv is for reduction, whereas azobenzene, and azoxybenzene are inert toward this reagent. Cyclohexanone oxime is reduced consuming 2.0 equiv of hydride for reduction at a moderate rate. Pyridine is inert toward this reagent. Disulfides and sulfoxides are reduced slowly, whereas sulfide, sulfone, and sulfonate are inert under these reaction conditions. Sulfonic acid evolves 1 equiv of hydrogen instantly, but reduction is not proceeded.

• Journal of Electrochemical Science and Technology
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• v.2 no.4
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• pp.204-210
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• 2011

Thin film electrodes have been intensively studied for active materials and current collectors to enhance the electrochemical performance. Here, porous structures of nickel-based oxide films, consisting of nickel oxide and copper (II) oxide, which was derived from the copper substrate during the annealing process, were deposited on metallic copper foils. The half-cell tests revealed excellent capacity retention after $80^{th}$ charge/discharge cycles. Some films showed an excess of the theoretical capacity of nickel oxides, which mainly originate from partially oxidized copper substrates during annealing. These results exhibit that both a preparation method of an active materials and partially oxidized current collectors could be important roles to apply thin film electrodes.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.19 no.2
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• pp.225-231
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• 2021

The reaction between Li₂CO₃ and Cl₂ was investigated to verify its occurrence during a carbon-anode-based oxide reduction (OR) process. The reaction temperature was identified as a key factor that determines the reaction rate and maximum conversion ratio. It was found that the reaction should be conducted at or above 500℃ to convert more than 90% of the Li₂CO₃ to LiCl. Experiments conducted at various total flow rate (Q) / initial sample weight (W_i) ratios revealed that the reaction rate was controlled by the Cl₂ mass transfer under the experimental conditions adopted in this work. A linear increase in the progress of reaction with an increase in Cl₂ partial pressure (pCl₂) was observed in the pCl₂ region of 2.03-10.1 kPa for a constant Q of 100 mL·min^-1 and W_i of 1.00 g. The results of this study indicate that the reaction between Li₂CO₃ and Cl₂ is fast at 650℃ and the reaction is feasible during the OR process.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.14 no.6
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• pp.267-271
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• 2004

Lithium cobalt oxide $(LiCoO_2)$ cathode powders for rechargeable battery have been successfully prepared using urea hydrolysis method. The obtained hydrolysis-derived precursors with different Li/Co molar ratio were calcined at various temperatures. Low temperature phase $(LT-LiCoO_2)$ and high temperature phase $(HT-LiCoO_2)$ were obtained after calcination at $500^{\circ}C$ for 2 hr, and phase transformation from $LT-LiCoO_2{\;}to{\;}HT-LiCoO_2$ was completely occurred over $700^{\circ}C$. The layered structure of $LiCoO_2$ was well developed with a rise in the calcination temperature. Charge-discharge test show that the lithium cobalt oxide with 1.2 molar ratio prepared at $800^{\circ}C$ has an initial discharge capacity as high as 152 mAh/g, and the relatively stable cycling characteristic with 9.2 % of capacity fading was obtained after 40th charge-discharge test.