• Applied Chemistry for Engineering
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• v.10 no.4
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• pp.620-627
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• 1999

Electrochemical properties of the Al current collector being used in lithium ion batteries have been studied in the 4 different aprotic electrolytes(1 M $LiBF_4$ EC : DMC, 1 M $LiBF_4$ EC : EMC. 1 M $LiPF_6$ EC : DMC. 1 M $LiPF_6$ EC : EMC) employing cyclic voltammetry and impedance measurement. Al electrode showed a wide range of the electrochemical window(0.5~4.1 V vs. $Li/Li^{+}$). However, solid interfacial materials has been formed on the Al surface due to reduction of impurities($H_2O$, $O_2$, etc), lithium salts, and electrolytes at low applied potentials, and aluminum oxides in the highly oxidizing potential as well. Especially, Al current collector was susceptible to localized in consequence of impurities in electrolytes.

• Journal of the Microelectronics and Packaging Society
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• v.10 no.2
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• pp.13-17
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• 2003

In this study, new LTCC materials of $ZnWO_4$-LiF system were developed for the application to RF Module fabrication. Pure $ZnWO_4$ must be sintered above $1050^{\circ}C$ in order to obtain up to 98% of full density. The measured dielectric constant ($\epsilon_r$)quality factor ($Q{\times}f0$), and temperature coefficient of resonant frequency ($\tau_f$ were 15.5, 74000 GHz, and $-70ppm^{\circ}C$, respectively. LiF addition resulted in a liquid phase formation at 81$0^{\circ}C$ due to interaction between ZnWO$_4$ and LiF. Therefore, ZnWO$_4$ with 0.5∼1.5 wt% LiF could be densified at $850^{\circ}C$. In the given LiF addition range, the sintering shrinkage increased with increasing LiF content. Addition of LiF slightly lowered the dielectric constant from 15.5 to 14.2∼15 due to lower dielectric constant of LiF. Qxfo value decreased with increasing LiF content. This can be explained in terms of the interaction between LiF and $ZnWO_4$, and inhomogeneity of grain structure.

• 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.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2004.06a
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• pp.285-291
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• 2004

As a part of assessment of the structural material for the molten salt handling system, corrosion behavior of Inconel 718, X-750, Haynes 75 and Haynes 263 alloys in the molten salt of LiCl-Li$_2$O-O$_2$was investigated in the range of temperature; $650^{\circ}C$, time; 24~168h, $Li_2O$; 3wt%, mixed gas; Ar~10%$O_2$. In the molten salt of LiCl-$Li_2O-O_2$, the order corrosion rate was Haynes 263 ＜ Haynes 75 ＜ Inconel X-750 ＜ Inconel 718. Haynes 263 alloy showed the highest corrosion resistance among the examined alloys. Corrosion products of alloys were as fellows: Haynes 75: $Cr_2O_4$, $NiFe_2O_4$, $LiNiO_2$, $Li_2NiFe_2O_4$, Inconel 718; $Cr_2O_4$, $NiFe_2O_4$, Haynes 263; $Li(Ni,Co)O_2$, $NiCr_2O_4$, $LiTiO_2$, Inconel X-750; $Cr_2O_3$, $NiFe_2O_4$,$FeNi_3$, (Al,Nb,Ti)$O_2$. Haynes 263 showed local corrosion behavior and Haynes 75, Inconel 718 and Inconel X-750 showed uniform corrosion behavior.

• Journal of the Korean Institute of Gas
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• v.2 no.4
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• pp.47-52
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• 1998

Water vapor absorption performance of four components solution ($LiBr+LiNO_3+LiC1+H_2O$) which could be substituted for commonly used $LiBr/H_2O$ solution in water cooled abosorption chiller is tested using a vertical tube absorber. Inlet solution concentration, inlet solution temperature, solution flow rate and inlet temperature of cooling water is varied as experimental parameters. The results of the experiment of water vapor absorption performance show that four components solution should have $2\%$ higher concentration for equal absorption capacity of $LiBr/H_2O$. But considering that four components solution have higher solubility than LiBr solution about $3\%$ high oncentration, four components solution ($LiBr+LiNO_3+LiC1+H_2O$) have more absorption capacity than LiBr solution in actual absorption chiller and can be applied to a small or air cooled absorption chiller.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.11a
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• pp.109-112
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• 1996

The purpose of this study is to research and develop solid polymer electrolyte(SPE) for all-stolid-state lithium battery. We investigated conductivity, electrochemical properites and impedence spectroscopy of poly(ethylene oxide)[PEO]/poly(vinylidene fluoride)[PVOF] blend electrolytes and charge/discharge cycling of LiCoO$_2$/SPE/Li cell. By adding PVDF and plasticizer to PEO-LICIO$_4$electrolyte, its condustivity was higher than that of PEO-LiCIO$_4$electrolyte. Also PEO$_4$PVDF$_4$LiClO$_4$PC$_{5}$EC$_{5}$ remains stable up to 4.4V vs Li/Li. The discharge capacity of the LiCoO$_2$composite cathode was 92mAh/g based on LiCoO$_2$.EX>.

• 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 the Korean Ceramic Society
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• v.55 no.1
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• pp.21-35
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• 2018

Spinel $LiNi_{0.5}Mn_{1.5}O_4$ has received great attention as one of the most outstanding cathode materials for Li-ion batteries (LIBs) because of its high energy density resulting from the operating voltage of ~ 4.7 V (vs. $Li^+/Li$) based on the $Ni^{2+}/Ni^{4+}$ redox reaction. However, $LiNi_{0.5}Mn_{1.5}O_4$ is known to suffer from undesirable side reactions with the electrolyte at high voltage as well as Mn dissolution from the structure. These issues prevent the realization of the optimal electrochemical performance of $LiNi_{0.5}Mn_{1.5}O_4$. Extensive research has been conducted to overcome these issues. This review presents an overview of the various surface-modification methods available to improve the electrochemical properties of $LiNi_{0.5}Mn_{1.5}O_4$ and provides perspectives on further research aimed at the application of $LiNi_{0.5}Mn_{1.5}O_4$ as a cathode material in commercialized LIBs.

• Applied Chemistry for Engineering
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• v.7 no.3
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• pp.433-442
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• 1996

Electrochemical characteristics and physical properties of polymer electrolyte which immobilized lithium salts such as $LiClO_4$ and $LiCF_3SO_3$ and plasticizers such as ethylene carbonate(EC) and propylene carbonate(PC) in high molecular weight poly(ethylene oxide)[PEO] polymer was investigated. PEO-Li based polymer electrolyte with plasticizers showed ionic conductivity of $10^{-4}S/cm$ at room temperature and high electrochemical stability up to 4.5 V(vs. $Li^+/Li$), so it can be applied to lithium secondary battery. The crystallinity of PEO decreased with the addition of lithium salts and plasticizers, especially $LiClO_4$ and PC showed more effective than and $LiCF_3SO_3$ and EC. Glass transition temperature($T_g$) of polymer electrolyte increased with increasing lithium salt concentration whereas melting temperature ($T_m$) decreased. Polymer electrolyte with plasticizers crystallized at $6^{\circ}C$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.5
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• pp.398-402
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• 2012

Synthesis of $Li_2MnSiO_4$ was attempted by the conventional solid-state reaction method, and the phase formation behavior according to the change of the calcination condition was investigated. When the mixture of the three source materials, $Li_2O$, MnO and $SiO_2$ powders, were used for calcination in air, it was difficult to develop the $Li_2MnSiO_4$ phase because the oxidation number of $Mn^{2+}$ could not be maintained. Therefore, two-step calcination was applied: $Li_2SiO_3$ was made from $Li_2O$ and $SiO_2$ at the first step, and $Li_2MnSiO_4$ was synthesized from $Li_2SiO_3$ and MnO at the second step. It was easy to make $Li_2MnSiO_3$ from $Li_2O$ and $SiO_2$. $Li_2MnSiO_4$ single phase was developed by the calcination at $900^{\circ}C$ for 24 hr in Ar atmosphere as the oxidation of $Mn^{2+}$ was prevented. However, the $Li_2MnSiO_4$ was ${\gamma}-Li_2MnSiO_4$, one of the polymorph of $Li_2MnSiO_4$, which could not be used as the cathode materials in Li-ion batteries. By applying the additional low temperature annealing at $400^{\circ}C$, the single phase ${\beta}-Li_2MnSiO_4$ powder was synthesized successfully through the phase transition from ${\gamma}$ to ${\beta}$ phase.