• Bulletin of the Korean Chemical Society
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• v.33 no.1
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• pp.65-68
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• 2012

Novel type $Li_{1.1}V_{0.9-2x}W_xMo_xO_2$ powders were prepared by a solid-state reaction of $Li_2CO_3$, $V_2O_3$, $WO_2$ and $MoO_2$ precursors in a nitrogen atmosphere containing 10 mol % hydrogen gas, and assessed as anode materials in lithium-ion batteries. The specific charge and discharge capacities of the $Li_{1.1}V_{0.9-2x}W_xMo_xO_2$ anodes were higher than those of the bare $Li_{1.1}V_{0.9}O_2$ anode. The cyclic efficiency of these anodes was approximately 73.3% at the first cycle, regardless of the presence of W and Mo doping. The composite anode, which was composed of $Li_{1.1}V_{0.75}W_{0.075}Mo_{0.075}O_2$ (20 wt %) and natural graphite (80 wt %), demonstrated reasonable specific capacity, high cyclic efficiency, and good cycling performance, even at high rates without capacity fading.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.8 no.1
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• pp.71-76
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• 2010

The electrorefining process, one of main processes which are composed of pyroprocess to recover the useful elements from spent fuel, and the domestic development of electrorefiner have been reviewed. The electrorefiner is composed of an anode basket containing reduced spent fuel such as uranium, transuranic and rare earth elements, and a solid cathode, which are in LiCl-KCl eutectic electrolyte. Oxidation (dissolution) reaction occurs on the anode and a pure uranium is electrochemically reduced (deposited) on the solid cathode. By application of graphite cathode, which has a self-scrapping characteristics for the uranium deposits, and a recovery of the fallen deposits by a screw conveyer, a high-throughput continuous electrorefiner with a capacity of 20 kgU/day has been developed.

• Journal of the Korean Ceramic Society
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• v.45 no.4
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• pp.245-249
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• 2008

The SiC and ZrC are critical and essential materials in TRISO coated fuel particles since they act as protective layers against diffusion of metallic and gaseous fission products and provides mechanical strength for the fuel particle. However, SiC and ZrC have critical disadvantage that SiC loses chemical integrity by thermal dissociation at high temperature and mechanical properties of ZrC are weaker than SiC. In order to complement these problems, we made new combinations of the coating layers that the ZrC layers composed of SiC. In this study, after Silicon carbide(SiC) were chemically vapor deposited on graphite substrate, Zirconium carbide(ZrC) were deposited on SiC/graphite substrate by using Zr reaction technology with Zr sponge materials. The different morphologies of sub-deposited SiC layers were correlated with microstructure, chemical composition and mechanical properties of deposited ZrC films. Relationships between deposition pressure and microstructure of deposited ZrC films were discussed. The deposited ZrC films on SiC of faceted structure with smaller grain size has better mechanical properties than deposited ZrC on another structure due to surface growth trend and microstructure of sub-deposited layer.

• Resources Recycling
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• v.9 no.4
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• pp.3-15
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• 2000

Reduction of Electric Arc Furnace dust with carbon (graphite) was studied at the temperature range of $800^{\circ}C$ to $1100^{\circ}C$ in Ar gas atmosphere. The briquetted dust with graphite powder was heated in a vertical tube furnace for given reaction time and Quenched in Ar gas atmosphere. It was found that initially the reduction of Zn was chemically controlled and the activation energy was about 120 KJ/mole. Because the almost all of Pb was removed with Cl in the form of $PbCl_2$, it is considered that Pb is removed by chloride reduction. Cu was vaporized as a chloride up to 30% of its original content, but the remaining of Cu would be accumulated with the reduced iron. and also, Cd was removed completely within 15 min. at $1000^{\circ}C$.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.80-80
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• 2010

Graphene has attracted tremendous attention for the last a few years due to it fascinating electrical, mechanical, and chemical properties. Up to now, several methods have been developed exclusively to prepare graphene, which include micromechanical cleavage, polycrystalline Ni employing chemical vapor deposition technique, solvent thermal reaction, thermal desorption of Si from SiC substrates, chemical routes via graphite intercalation compounds or graphite oxide. In particular, polycrystalline Ni foil and conventional chemical vapor deposition system have been widely used for synthesis of large-area graphene. [1-3] In this study, synthesis of mono-layer graphene on a Ni foil, the mixing ratio of hydrocarbon ($CH_4$) gas to hydrogen gas, microwave power, and growth time were systemically optimized. It is possible to synthesize a graphene at relatively lower temperature ($500^{\circ}C$) than those (${\sim}1000^{\circ}C$) of previous results. Also, we could control the number of graphene according to the growth conditions. The structural features such as surface morphology, crystallinity and number of layer were investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM), transmission electron microscopy (TEM) and resonant Raman spectroscopy with 514 nm excitation wavelength. We believe that our approach for the synthesis of mono-layer graphene may be potentially useful for the development of many electronic devices.

• Journal of the Korean Recycled Construction Resources Institute
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• v.12 no.1
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• pp.40-46
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• 2024

A novel approach is presented to address issues associated with the use of strong acidic solutions for the leaching of magnesium oxide (MgO) from spent magnesia-carbon refractories. An ultrasonic flotation and separation process is employed, with a mildly acidic solvent, acetic acid, used to selectively chelate MgO from the spent refractories. When using 2 M acetic acid as a solvent, the recovery of the graphite exhibited 99.7 % with high purity of 72.7 %, showing a significant improvement compared to using water as the solvent. Furthermore, the technology presented in this study offers a method for producing magnesium acetate through the reaction of MgO in spent refractory with acetic acid, providing a means for the purification and separation of graphite.

• Journal of the Korean Electrochemical Society
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• v.19 no.3
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• pp.69-79
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• 2016

Lithium ion battery with high energy density is expanding its application area to electric automobile and electricity storage field beyond existing portable electric devices. Such expansion of an application field is demanding higher characteristic and stable long life characteristic of an anode material, the natural graphite that became commercialized in lithium ion battery. This thesis produced cathode by using natural graphite anode material, analyzed creation of the cathode SEI film created due to initial reaction by using electrolyte additives, VC (vinylene carbonate), VEC (vinyl ethylene carbonate), and FEC (fluoroethylene carbonate), and considered correlation with the accompanying electrochemical transformation. This study compared and analyzed the SEI film variation of natural graphite cathode according to the electrolyte additive with SEI that is formed at the time of initial filling and cathode of $60^{\circ}C$ life characteristic. At the time of initial filling, the profile showed changes due to the SEI formation, and SEI was formed in No-Additive in approximately 0.9 V through EVS, but for VC, VEC, and FEC, the formation reaction was created above 1 V. In $60^{\circ}C$ lifespan characteristic evaluation, the initial efficiency was highest in No-Additive and showed high contents percentage, but when cycle was progressed, the capacity maintenance rate decreased more than VC and FEC as the capacity and efficiency at the time of filling decreased, and VEC showed lowest performance in efficiency and capacity maintenance rate. Changes of SEI could not be verified through SEM, but it was identified that as the cycle of SEI ingredients was progressed through FT-IR, ingredients of Alkyl carbonate ($RCO_2Li$) affiliation of the $2850-2900cm^{-1}$ was maintained more solidly and the resistance increased as cycle was progressed through EIS, and specially, it was identified that the resistance due to No-Additive and SEI of VEC became very significant. Continuous loss of additives was verified through GC-MS, and the loss of additives from partial decomposition and remodeling of SEI formed the non-uniform surface of SEI and is judged to be the increase of resistance.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2002.05a
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• pp.29-34
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• 2002

[ $Nb/MoSi_2-ZrO_2$ ] laminate composites have been successfully fabricated by alternately stacking $MoSi_2-ZrO_2$ powder layer and Nb sheet, followed by hot pressing in a graphite mould. The fabricating parameters were selected as hot press temperatures. The instrumented Charpy impact test was carried out at the room temperature in order to investigate the relationship between impact properties and fabricating temperatures. The interfacial shear strength between $MoSi_2-ZrO_2$ and Nb, which is associated with the fabricating temperature and the growth of interfacial reaction layer, is also discussed. The plastic deformation of Nb sheet and the interfacial delamination were macroscopically observed. The $Nb/MoSi_2-ZrO_2$ laminate composites had the maximum impact value when fabricated at 1623K, accompanying the increase of fracture displacement and crack propagation energy. The interfacial shear strength of $Nb/MoSi_2-ZrO_2$ laminate composites increased with the growth of interfacial reaction layer, which resulted from the increase of fabricating temperature. there is an appropriate interfacial shear strength for the enhancement of impact value of $Nb/MoSi_2-ZrO_2$ laminate composites. A large increase of interfacial shear strength restrains the plastic deformation of Nb sheet.

• Journal of the Korean Ceramic Society
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• v.36 no.2
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• pp.172-177
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• 1999

Graphite and carbonaceous materials showed an excellent capability as a negative electrode in Li-ion batteries because Li-ion can be intercalated and de-intercalated reversibly within most carbonaceous materials of layered structure. Also, the electrochemical potential of Li-intercalated carbon anode is almost identical with that of Li metal. In the present study, mesocarbon microbeads(MCMB) were used as anode electrode and its properties of charge/discharge and interfacial reaction with electrolyte were studied by Potentiostat/Galvanostat test, FT-IR analysis, XRD and SEM. The passivation film of solid-state was formed as the interface between electrode and electrolyte as the cell reaction began and, once formed, became thicker with repeated charge/discharge process. Also, the relationship between the passivation film formed at the electrode interface and storage capacity was discussed.

• Journal of the Korean Chemical Society
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• v.16 no.5
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• pp.271-283
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• 1972

The rate Constants and energies of activation for the Combustion reaction of Korean anthracites have obtained by DTA method using the following rate equation derived by authors. $K=\frac{C_3{\cdot}W_0}{{\Delta}H{\cdot}{\Delta}C{\cdot}M{\cdot}S_A}(\frac{dy}{dt}+A(y-y_3))$ The anthracites of various ranks were treated at the different temperatures in the furnace. The probable combustion reaction mechanisms have discussed with the results obtained by the X-ray diffraction method, IR spectroscophic analysis, and gas chromatography. By the intensity of d(002) Values, it was confirmed that a parts of the amorphous carbon was converted to graphite form by heat treatment. The appreciable amounts of CO gas were expelled in the combustion process and it appeared that a little amount of the gas came from the catalytic decomposition of anthracites, The functional groups such as -OH, -SH, -NH, $-CH_2-CH_3,$ -CO, -COC-. and polycondensed aromatic rings in anthracites have observed by IR spectrophotometric analysis.