• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.202-203
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• 2005

To recognize whether admixture affects some $(Ba_{0.6}Sr_{0.4})TiO_3$, powder in this research $Li_2CO_3$, MgO, $MnO_2$ adding each 3 wt % by Tape casting method thick film make. Sitering temperature lowered 1300$^{\circ}C$ adding $Li_2CO_3$, and density is 5.942g/$cm^3$, and specific inductive capacity increases about decuple and displayed 4000. Climbed sitering temperature 1400$^{\circ}C$ adding MgO, specific inductive capacity reduced 1/2 times. Lowered sintering temperature 1325$^{\circ}C$ low adding $MnO_2$.

• Metals and materials international
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• v.24 no.6
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• pp.1394-1402
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• 2018

This study investigates the mechanism of MnS precipitation on $Al_2O_3-SiO_2$ inclusions during the solidification of non-oriented silicon steel, especially the influence of the phase structures and sizes of the oxides on the MnS precipitation, by scanning electron microscopy and transmission electron microscopy coupled with energy dispersive spectrometry. The investigation results show that MnS tends to nucleate on submicron-sized $Al_2O_3-SiO_2$ inclusions formed by interdendritic segregation and that it covers the oxides completely. In addition, MnS can precipitate on micron-sized oxides and its precipitation behavior is governed by the phase structure of the oxides. The MnS embryo formed in a MnO-containing oxide can act as a substrate for MnS precipitation, thus permitting further growth via diffusion of solute atoms from the matrix. MnS also precipitates in a MnO-free oxide by the heterogeneous nucleation mechanism. Furthermore, MnS is less prone to precipitation in the $Al_2O_3$-rich regions of the $Al_2O_3-SiO_2$ inclusions; this can be explained by the high lattice disregistry between MnS and $Al_2O_3$.

• Journal of Electrochemical Science and Technology
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• v.11 no.4
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• pp.411-420
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• 2020

Undesirable interfacial reactions between the cathode and sulfide electrolyte deteriorate the electrochemical performance of all-solid-state cells based on sulfides, presenting a major challenge. Surface modification of cathodes using stable materials has been used as a method for reducing interfacial reactions. In this work, a precursor-based surface modification method using Zr and Mo was applied to a LiNi_0.6Co_0.2Mn_0.2O₂ cathode to enhance the interfacial stability between the cathode and sulfide electrolyte. The source ions (Zr and Mo) coated on the precursor-surface diffused into the structure during the heating process, and influenced the structural parameters. This indicated that the coating ions acted as dopants. They also formed a homogenous coating layer, which are expected to be layers of Li-Zr-O or Li-Mo-O, on the surface of the cathode. The composite electrodes containing the surface-modified LiNi_0.6Co_0.2Mn_0.2O₂ powders exhibited enhanced electrochemical properties. The impedance value of the cells and the formation of undesirable reaction products on the electrodes were also decreased due to surface modification. These results indicate that the precursor-based surface modification using Zr and Mo is an effective method for suppressing side reactions at the cathode/sulfide electrolyte interface.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.6 no.3
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• pp.327-340
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• 1996

In this study, a series of $LiNbO_{3}$ crystals with different [Li]/[Nb] ratios, congruent $LiNbO_{3}$ crystals with doped Mg and with Mg and codoped with Mn were grown by the Czocharalski method. These were investigated by UV and IR spectrophotometry. Stoichiometry dependences of the UV absorption edge and the $OH^{-}$ absorption spectra were studied with different [Li]/[Nb] ratios. The position of the UV absorption edge adn the shape and peak point of the $OH^{-}$ absorption spectra changed monotonously upto a critical concentration of Mg ions. The mechanism of the incorporation of Mg ions changes at this concentration. The decomposition of the $OH^{-}$ absorption spectra using a Gaussian lineshape function showed that in Li-deficient crystals the absorption spectra consist of five components in contrast to more or less perfect stoichiometric crystals which reveal to three components. On the basis of these results, the intrinsic and the extrinsic defect structure models in $LiNbO_{3}$ crystals were examined. The behaviour of $\nu$ (OH) reflects the defect structure and supports the Li-site vacancy model as the intrinsic defect structure model and the corresponding extrinsic defect model. A brief discussion is also given of the behaviour of $\nu$ (OH) in $LiNbO_{3}$ crystals simultaneously doped with several kinds of impurity.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.387-390
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• 1999

To improve the cycle performance LiM $n_2$ $O_4$as the cathode of 4V class lithium secondary batteries, the cathode properties of the cubic spinel phases LiM $g_{x}$ /M $n_{2-x}$/ $O_4$ synthesized at 80$0^{\circ}C$ were examined. All cathode material showed spinel phase based on cubic phase in X-ray diffraction however. other peaks gradually exhibited and became intense with the increase of x value in LiM $g_{x}$ /M $n_{2-x}$/ $O_4$. The cycle performance of the LiM $g_{x}$ /M $n_{2-x}$/ $O_4$was improved by the substitution of $Mg^{2+}$ for M $n^{3+}$ in the octahedral sites. Specially LiM $g_{0.1}$/M $n_{1.9}$ / $O_4$cathode materials showed the charge and discharge capacity of about 130~125mAh/g at first cycle and about 105mAh/g after 50th cycle. It is excellent than that of pure LiM $n_{2}$/ $O_4$ which 125mAh/g at first cycle 70mAh/g at 50th. In addition cathode material prepared at 80$0^{\circ}C$ for 24hr and 42hr in the charge and discharge capapcity as well as the cycle stability.ility.y.y.

• Bulletin of the Korean Chemical Society
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• v.34 no.7
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• pp.1995-2000
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• 2013

Layered $Li_{1.2}(Fe_{0.16}Mn_{0.32}Ni_{0.32})O_2$ was prepared by the mixed hydroxide method at various temperatures. Xray diffraction (XRD) pattern shows that this material has a ${\alpha}-NaFeO_2$ layered structure with $R{\bar{3}}m$ space group and that cation mixing is reduced with increasing synthesis temperature. Scanning electron microscopy (SEM) reveals that nano-sized $Li_{1.2}(Fe_{0.16}Mn_{0.32}Ni_{0.32})O_2$ powder has uniform particle size distribution. X-ray absorption near edge structure (XANES) analysis is used to study the local electronic structure changes around the Mn, Fe, and Ni atoms in this material. The sample prepared at $700^{\circ}C$ delivers the highest discharge capacity of 207 $mAhg^{-1}$ between 2-4.5 V at 0.1 $mAcm^{-2}$ with good capacity retention of 80% after 20 cycles.

• Journal of the Korean Electrochemical Society
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• v.16 no.3
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• pp.151-156
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• 2013

As the cathode material for li-ion battery, $LiNi_{0.5}Mn_{0.3}Co_{0.2}O_2$ were synthesized by supercritical hydrothermal method and calcined $850^{\circ}C$ and $900^{\circ}C$ for 10hrs in air. The effect of temperature in the heat treatment on the powder and its performance were studied of xray diffraction pattern, SEM-image, physical properties and electrochemical behaviors. As a result, calcined at $900^{\circ}C$ material particle size more increase than calcined at $850^{\circ}C$ material, especially shows excellent electrochemical performance with initial reversible specific capacity of 163.84 mAh/g (0.1C/2.0-4.3V), 186.87 mAh/g (0.1C/2.0-4.5V) and good capacity retention of 91.49% (0.2C/2.0-4.3V) and 90.36% (0.2C/2.0-4.5V) after 50th charge/discharge cycle.

• Journal of the Korean Electrochemical Society
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• v.12 no.1
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• pp.81-87
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• 2009

An indium-tin oxide (ITO) coated spinel manganese oxide (${LiMn_2}{O_4}$, LMO) is prepared and its high-temperature ($55^{\circ}C$) cycle performance and rate capability are examined. A severe electrolyte decomposition and film deposition is observed on the un-coated ${LiMn_2}{O_4}$ cathode, which leads to a significant electrode polarization and capacity fading. Such an electrode polarization is, however, greatly reduced for the ITO-coated (> 2 mol%) LMO cathode, which leads to an improved cycle performance. This can be rationalized by a suppression of electrolyte decomposition, which is in turn indebted to a decrease in the direct contact area between LMO and electrolyte. The suppression of film deposition on the ITO-coated LMO cathode is confirmed by infra-red spectroscopy. The rate capability is also improved by the surface coating, which may be resulted from a suppression of resistive film deposition and high electric conductivity of ITO itself.

• Journal of the Korean Electrochemical Society
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• v.17 no.4
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• pp.222-228
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• 2014

Ni-rich system $Li[Ni_{1-x-y}Co_xMn_y]O_2$ of lithium secondary battery cathode material keep a high discharge capacity. However, by the Ni content increases, there is a problem that the electrochemical properties and stability of the structure are reduced. In order to solve these problems, research for positive ion doping is performed. The one of the cathode material, barium-doped $Li[Ni_{0.6-x}Ba_xCo_{0.1}Mn_{0.3}]O_2$ (x=0.01), was synthesized by the precursor, $Ni_{0.6}Co_{0.1}Mn_{0.3}(OH)_2$, from the co-precipitation method. The barium doped materials have studied the structural and electrochemical properties. The analysis of structural properties, results of X-ray diffraction analysis, and those results confirmed the change of the lattice from the binding energy in the structure by barium doping. Increased stability of the layered structure was observed by $I_{(006)}+I_{(102)}/I_{(101)}$(R-factor) ratio decrease. we expected that the electrochemical characteristics are improved. 23 mAh/g discharge capacity of barium-doped $Li[Ni_{0.6-x}Ba_xCo_{0.1}Mn_{0.3}]O_2$ (x=0.01) electrode is higher than discharge capacity of $Li[Ni_{0.6}Co_{0.1}Mn_{0.3}]O_2$ due to decrease overvoltage. And, through the structural stability was confirmed that improved the cycle characteristics. We caused a reduction in charge transfer resistance between the electrolyte and the electrode was confirmed that the C-rate characteristics are improved.

• 한국전기화학회:학술대회논문집
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• 2005.04a
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• pp.52-52
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• 2005