• Journal of Electrochemical Science and Technology
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• 제2권3호
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• pp.180-185
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• 2011

The layered lithium-manganese oxide ($Li_2MnO_3$) as a cathode material of lithium ion secondary batteries was prepared and characterized the physico-chemical and electrochemical properties. The morphological and structural changes of MnO(OH) and $Li_2MnO_3$ are closely connected to the changes of electrochemical properties. The crystallinity of $Li_2MnO_3$ is enhanced as the annealing temperature increase, but its capacity is reduced due to the easier structural changes of less crystalline $Li_2MnO_3$ than highly crystalline one. Moreover, the addition of buffer material such as MnO(OH) into cathode causes to reduce the morphological and structural changes of layered $Li_2MnO_3$ and increase the discharge capacity and cycleability.

• 한국결정성장학회지
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• 제9권1호
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• pp.126-131
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• 1999

Hot-wall epitaxy법으로 $Cd_{1-x}Mn_xTe$박막을 GaAs (100) 기판위에 성장시켰다. XRD 측정으로부터 CdTe/GaAs(100) 박막은 기판과 같은 (100)면의 단결정 박막으로, $Cd_{1-x}Mn_xTe$박막은 Mn의 조성비 x가 증가함에따라 다결정 박막으로 성장되었으며, 박막의 격자상수는 x의 증가에 따라 덩어리 결정의 경우와 비슷한 기울기로 감소함을 확인하였다. x의 변화에 대한 $Cd_{1-x}Mn_xTe$ 박막의 PL 측정으로부터 받개와 퍼텐셜 요동에 의하여 포획된 엑시톤의 재결합 피크인 $L_1$과 $L_2$를 관측하였으며, $L_1$피크는 x=0.09 시료에서만 관측되었고 x값이 증가하면 사라졌다. x $\ge$0.2의 경우에는 $L_2$피크가 강하게 나타나고 x$\ge$ 0.4에서는 $Mn^{2+}$이온의 intra 천이에 의한 2.0eV 근처의 피크가 강하게 나타났다. x>0.4에서 $Mn^{2+}$이온에 의한 2.0eV 피크는 pinning이 일어나 변화가 거의 없이 일정하였다.

• Bulletin of the Korean Chemical Society
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• 제34권2호
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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.

• 한국세라믹학회지
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• 제42권7호
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• pp.503-508
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• 2005

A simple and effective method for the synthesis of LiMn$_{2}$O$_{4}$ powder as a cathode material for lithium secondary battery is reported. Micrometer size LiMn$_{2}$O$_{4}$ was prepared by combustion synthesis technique employing initial mixture of l.l LiNO$_{3}$ -1.3Mn-0.7MnO$_{2}$-1NaCl composition. Parametric study of the combustion process including molar ratio of Mn/MnO$_{2}$ and NaCl concentration were carried out under air atmosphere. The combustion products obtained were additionally heat treated at the temperature 900$^{\circ}C$ and the washed by distilled water. The results of charging-discharging characteristics revealed that LiMn$_{2}$O$_{4}$ cell synthesized in the presence of NaCl had a high capacity and much better reversibility than one formed without NaCl An approximate chemical mechanism for LiMn$_{2}$O$_{4}$ formation is proposed.

• 한국전기전자재료학회논문지
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• 제37권2호
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• pp.215-222
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• 2024

Ni-rich cathode materials have been developed as the most promising candidates for next-generation cathode materials for lithium-ion batteries because of their high capacity and energy density. In particular, the electrochemical performance of lithium-ion batteries could be enhanced by increasing the contents of nickel ion. However, there are still limitations, such as low structural stability, cation mixing, low capacity retention and poor rate capability. Herein, we have successfully developed the nanorod-type Ni-rich cathode materials by using co-precipitation method. Particularly, the nanorod-type primary particles of LiNi_0.7Co_0.15Mn_0.15O₂ could facilitate the electron transfer because of their longitudinal morphology. Moreover, there were holes at the center of secondary particles, resulting in high permeability of the electrolyte. Lithium-ion batteries using the prepared nanorod-type LiNi_0.7Co_0.15Mn_0.15O₂ achieved highly improved electrochemical performance with a superior rate capability during battery cycling.

• 한국재료학회:학술대회논문집
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• 한국재료학회 1999년도 추계학술발표강연 및 논문개요집
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• pp.21-21
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• 1999

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2004년도 International Symposium on Powder Materials and Processing
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• pp.106-106
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• 2004

• 한국재료학회:학술대회논문집
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• 한국재료학회 1999년도 춘계학술발표강연 및 눈문개요집
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• pp.79-79
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• 1999

• 전기화학회지
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• 제9권4호
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• pp.158-169
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• 2006

The present article is concerned with the overview of the chemically/surface modified cubic spinel $LiMn_2O_4$ as a cathode electrode far lithium ion secondary batteries. Firstly, this article presented a comprehensive survey of the cubic spinel structure and its correlated electrochemical behaviour of $LiMn_2O_4$. Subsequently, the various kinds of the chemically/surface modified $LiMn_2O_4$ and their electrochemical characteristics were discussed in detail. Finally, this article reviewed our recent research works published on the mechanism of lithium transport through the chemically/surface modified $Li_{1-\delta}Mn_2O_4$ electrode from the kinetic view point by the analyses of the experimental potentiostatic current transients and ac-impedance spectra.

• E2M - 전기 전자와 첨단 소재
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• 제14권12호
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• pp.7-10
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• 2001

Orthorhombic type LiCo$_{x}$Mn$_{1-x}$ O$_2$(0$\leq$x$\leq$0.14) oxides have been synthesized by hydrothermal treatment of (Co$_{x}$Mn$_{1-x}$ )$_3$O$_4$precursors and LiOH aqueous solution at 17$0^{\circ}C$. As-synthesized powders showed well-ordered $\beta$-MaMnO$_2$structures, and the products were single crystalline particle oxides from TEM observations. The particle size decreased with increasing the amount of Co substituent. Much more improved capacity upon 100 cyclings was clearly seen in orthorhombic LiCo$_{0.1}$Mn$_{0.9}$O$_2$, comparing to orthorhombic LiMnO$_2$./TEX>.EX>.