• Korean Journal of Soil Science and Fertilizer
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• v.46 no.4
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• pp.260-269
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• 2013

Two single-crystals of fully dehydrated, partially $Li^+$-exchanged zeolites X (Si/Al = 1.09, crystal 1) and Y (Si/Al = 1.56, crystal 2), were prepared by flow method using 0.1 M $LiNO_3$ at 393 K for 48 h, respectively, followed by vacuum dehydration at 673 K and $1{\times}10^{-6}$ Torr. Their structures were determined by single-crystal X-ray diffraction techniques in the cubic space group $Fd\bar{3}$ and $Fd\bar{3}m$ at 100(1) K for crystals 1 and 2, respectively. They were refined to the final error indices $R_1/wR_2$ = 0.065/0.211 and 0.043/0.169 for crystals 1 and 2, respectively. In crystal 1, about 53 $Li^+$ ions per unit cell are found at three distinct positions; 9 at site I', 19 at another site I', and the remaining 25 at site II. The residual 25 $Na^+$ ions occupy three equipoints; 2 are at site I, 7 at site II, and 16 at site III'. In crystal 2, about 31 $Li^+$ ions per unit cell occupy sites I' and II with occupancies at 22 and 9, respectively; 3, 4, 23, and 3 $Na^+$ ions are found at sites I, I', II, and III', respectively. The extent of $Li^+$ ion exchange into zeolite X (crystal 1) is higher than that of zeolite Y (crystal 2), ca. 73% and 56% in crystals 1 and 2, respectively.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.4
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• pp.316-322
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• 2001

Cathode materials $LiMn_{2-y}$$M_{y}$ $O_4$(M=Zn and Mg) were obtained by reacting the mixture of LiOH.$H_2O$, Mn $O_2$ and MgO ar ZnO at 80$0^{\circ}C$ for 36h in an air atmosphere. These materials showed an extended cycle life in lithium-anode cells working at room temperatue in a 3.0 to 4.3V potential window. Among these materials, LiM $n_{1.9}$M $g_{0.1}$ $O_4$ showed the best cycle performance in terms of the capacity and cycle life. The discharge capacities of the cathode for the Li/LiM $n_{1.9}$ $M_{0.1}$ $O_4$ cell at the 1st cycle and at the 70th cycle were about 120 and 105mAh/g, respectively. This cell capacity is retained by 88% after 70th cycle. In cyclic voltammetry measurement, all cells revealed tow oxidation peaks and reduction peaks. However, Li/$LiMn_{2-y}$$M_{y}$ $O_4$ cell substituted with Zn and Mg showed new reaction peak during reduction reaction.eaction.ion.ion.

• Journal of the Korean Chemical Society
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• v.35 no.4
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• pp.324-328
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• 1991

The Li$_2SO_4$ system containing various mol${\%}$ of CaSO$_4$ were synthesized. The structure and the electrical conduction of these system were studied at the temperature from 20 to 700$^{\circ}C$. In the region of CaSO$_4$ mol ratio higher than 0.05, it could be confirmed that Li$_2SO_4-CaSO_4$ system does not form solid solution. Due to the substituted Ca$^{2+}$, the transition temperature (monoclinic to cubic) is shifted to the low temperature. The ionic conduction of monoclinic Li$_2SO_4-CaSO_4$ increased with increasing lithium vacancy which was produced by substituted Ca$^{2+}$, but that fcc Li$_2SO_4-CaSO_4$ was not influenced by the substituted Ca$^{2+}$ ion.

• Korean Chemical Engineering Research
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• v.51 no.4
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• pp.460-464
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• 2013

A series of Mn compound were prepared by seed-assisted method. The seed used in this reaction was manufactured by calcination of $MnCO_3$ at various temperatures and effects of the calcination temperature on seed-assisted reaction were investigated. With increase of the calcination temperature, CMD (${\gamma}-MnO_2$) was recovered after seed-assisted reactions. LMO used as cathode active material in the Li-ion batteries were synthesized from Mn source obtained in the seed-assisted reaction and the electrochemical properties (rate capability, cycle life performance and specific capacity) of the LMO were investigated. The LMO synthesized from the CMD which is obtained by the reaction with seed prepared by calcination of $MnCO_3$ more than $350^{\circ}C$ shown good electrochemical properties.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.6 no.1
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• pp.44-55
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• 1996

Emerald (3BeO{\cdot}Al$_{2}$O_{3}{\cdot}6SiO_2 : Cr^{3+}$) single crystals were grown by flux method of $Li_2O-MoO_3 - V_2O_5$ system. The composition of starting materials were 1, 3, 5 mole ratio of $MoO_3 - V_2O_5/$Li_2O$, 20 - 15% of emerald content to flux composition and 1% of $Cr_2O_3$ colordopant to emerald composition. After mixing those were melted at $1100^{\circ}C$ in Pt crucible of electric furnace. Single crystal growth was cooled down slowly rate of $3^{\circ}C$/hr from $1100^{\circ}C$ to $650^{\circ}C$, for the cooling period it was controlled and prevented the nucleation of microcrystallite from variation of each thermal fluctuation range. Specially it has been obtained plenty of large emerald single crystal when thermal fluctuation was treated for cooling period at $1050 ~ 950^{\circ}C$, in 3 mole ratio of $V_2O_5 - MoO_3/Li_2O$ flux. Emerald single crystal growing effect and $Cr_{+3}$ ion of substitutional solid solution effect for $Al_{+3}$ ion was good than mole ratio of 5. Emerald single crystals were c (0001) hexagonal rystal face of preferencial direction and m (1010) post side. Emerald was hexagonal columnar greenish transparent and 2.65 ~ 2.66 of specific gravity.

• Journal of the Korean Chemical Society
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• v.57 no.1
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• pp.12-19
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• 2013

The single-crystal structure of fully dehydrated partially $Li^+$-exchanged zeolite Y, ${\mid}Li_{50}Na_{25}{\mid}[Si_{117}Al_{75}O_{384}]$-FAU, was determined by single-crystal synchrotron X-ray diffraction techniques in the cubic space group $Fd\bar{3}m$ at 100(1) K. Ion exchange was accomplished by flowing stream of 0.1 M aqueous $LiNO_3$ for 2 days at 293 K, followed by vacuum dehydration at 623 K and $1{\times}10^{-6}$ Torr for 2 days. The structure was refined using all intensities to the final error indices (using only the 801 reflections with ($F_o$ > $4{\sigma}(F_o)$) $R_1/R_2=0.043/0.140$. The 50 $Li^+$ ions per unit cell are found at three different crystallographic sites. The 19 $Li^+$ ions occupy at site I' in the sodalite cavity: the $Li^+$ ions are recessed 0.30 ${\AA}$ into the sodalite cavity from their 3-oxygens plane (Li-O = 1.926(5) ${\AA}$ and $O-Li-O=117.7(3)^{\circ}$). The 20 $Li^+$ ions are found at site II in the supercage, being recessed 0.23 ${\AA}$ into the supercage (Li-O = 2.038(5) ${\AA}$ and $O-Li-O=118.7(3)^{\circ}$). Site III' positions are occupied by 11 $Li^+$ ions: these $Li^+$ ions bind strongly to one oxygen atom (Li-O = 2.00(8) ${\AA}$). About 25 $Na^+$ ions per unit cell are found at four different crystallographic sites: 4 $Na^+$ ions are at site I, 5 at site I', 12 at site II, and the remaining 4 at site III'.

• Bulletin of the Korean Chemical Society
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• v.34 no.2
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• pp.433-436
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• 2013

Carbon-coated $Li_3V_2(PO_4)_3-LiMnPO_4$ composite cathode materials are first reported in this work, prepared by the mechanochemical process with a complex metal oxide as the precursor and sucrose as the carbon source. X-ray diffraction pattern of the composite material indicates that both olivine $LiMnPO_4$ and monoclinic $Li_3V_2(PO_4)_3$ co-exist. We further investigated the electrochemical properties of our $Li_3V_2(PO_4)_3-LiMnPO_4$ composite cathode materials using galvanostatic charging/discharging tests, where our $Li_3V_2(PO_4)_3-LiMnPO_4$ composite electrode materials exhibit the charge/discharge efficiency of 91.9%, while $Li_3V_2(PO_4)_3$ and $LiMnPO_4$ exhibit the efficiency of 87.7 and 86.7% in the first cycle. The composites display unique electrochemical performances in terms of overvoltage and cycle stability, displaying a reduced gap of 141.6 mV between charge and discharge voltage and 95.0% capacity efficiency after $15^{th}$ cycles.

• Journal of IKEEE
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• v.23 no.1
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• pp.1-8
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• 2019

In this paper, the electrical characteristics with various C-rates are tested with a high power series battery pack comprised of 18650 cylindrical nickel cobalt aluminum(NCA) lithium-ion battery. The electrical characteristics of discharge capacity test with 14S1P battery pack and electric vehicle (EV) cycle test with 4S1P battery pack are compared and analyzed by the various of C-rates. Multiple linear regression is used to estimate voltage imbalance of 14S1P and 4S1P battery packs with various C-rates based on experimental data. The estimation accuracy is evaluated by root mean square error(RMSE) to validate multiple linear regression. The result of this paper is contributed that to use for estimating the voltage imbalance of discharge capacity test with 14S1P battery pack using multiple linear regression better than to use the voltage imbalance of EV cycle with 4S1P battery pack.

• Composites Research
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• v.35 no.6
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• pp.365-370
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• 2022

According to the rapid growth of electric vehicle (EVs) and E-mobility market, Li-ion batteries are one of the most progressive technologies. The demand of LIBs with high energy capacity, rate performance and fast charging is continuously increasing, hence high-performance LIBs should be developed. Si is considered as the most promising anode material to improve energy density because of its high theoretical capacity. However, Si suffers large volume chances during the charging and discharge process, leading to the fast degradation of cycle performance. Therefore, polymeric binders play a key role in electrochemical performance of Si anode by efficiently enduring the Si expansion and maintaining the binding networks in electrode. In this review, we explain the role of polymeric binders in electrode and introduce the anode binders with enhanced mechanical and chemical properties which can improve electrochemical performances of Si-based anode.

• Journal of IKEEE
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• v.26 no.1
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• pp.10-18
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• 2022

Accurate SOC estimation is an important indicator of battery operation strategies, and many studies have been conducted. The simulation method which was mainly used in previous studies, is difficult to conduct real-time SOC estimation like real BMS environment. Therefore, this paper aims to implement a real-time battery SOC estimation embedded system and analyze problems that can arise during the verification process. In environment consisting of two Raspberry Pi boards, SOC estimation with the EKF uses data measured by the Simscape battery model. Considering that the operating characteristics of the battery vary depend on the temperature, the results were analyzed at various ambient temperatures. It was confirmed that accurate SOC estimation was performed even when offset fault and packet loss occurred due to communication or sensing problems. This paper proposes a guide for embedded system strategies that enable real-time SOC estimation with errors within 5%.