• 한국전기전자재료학회논문지
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• 제14권4호
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• pp.309-315
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• 2001

Crystallized $LiMn_{2-y}Mg_{y}O_4$ powder was prepared by calcing the mixture of LiOH.$H_2O$, $MnO_2$ and MgO at $800^{\circ}C$ for 36h in an air atmosphere. The structure of $LiMn_{2-y}Mg_{y}O_4$ crystallites was analyzed from powder X-ray diffraction data as a cubic spinel, space group Fd3m. Though all cathode material showed spinel phase based on cubic phase in X-ray diffraction, other peaks gradually exhibited and became intense with increasing y value in $LiMn_{2-y}Mg_{y}O_4$. However, ununiform which calculated by (111) face and (222) face was constant in spite of the increase of y value, except pure $LiMn_2O_4$. AC impedance of Li/$LiMn_{2-y}Mg_{y}O_4$ cells revealed the similar resistance of about $70\Omega$ before cycling. In addition, The impedance of Li/$LiMn_{1.9}Mg_{0.1}O_4$ cell changed during charge and discharge or after cycling.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집 Vol.3 No.2
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• pp.707-710
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• 2002

Spinel $LiMn_2O_4$ and $LiMn_{1.9}Mg_{0.05}Zn_{0.05}O_4$ powders were synthesized by solid-state method at $800^{\circ}C$ for 36h. Crystal structure and electrochemical properties were analyzed by X-ray diffraction, charge-discharge test, cyclic voltammetry and ac impedance to $LiMn_2O_4$ and $LiMn_{1.9}Mg_{0.05}Zn_{0.05}O_4/Li$. All cathode material showed spinel structure in X-ray diffraction. $LiMn_{1.9}Mg_{0.05}Zn_{0.05}O_4/Li$ cell substituted $Mg^{2+}$ and $Zn^{2+}$ showed excellent discharge capacities than other cells, which it presented about 120mAh/g at the 1st cycle and about 73mAh/g at the 250th cycle, respectively. AC impedance of $LiMn_{1.9}Mg_{0.05}Zn_{0.05}O_4/Li$ cells showed the similar resistance of about $65{\sim}110{\Omega}$ before cycling.

• 공업화학
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• 제9권5호
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• pp.774-780
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• 1998

스피넬 구조인 $LiMn_2O_4$의 안정성을 향상시키기 위해서 망간과 비슷한 이온반경을 갖는 여러 가지 금속원소, Mg, Fe, V, W, Cr, Mo들을 일부 치환하였으며 ($LiM_xMn_{2-x}O_4(0.05{\leq}x{\leq}0.02)$), 이 결과 $LiM_xMn_{2-x}O_4$ 정극은 정극물질로 사용할 경우 $LiMn_2O_4$보다 낮은 용량감소를 나타냈다. 그리고 화학확산계수의 측정 결과 $LiMg_{0.05}Mn_{1.9}O_4$와 $LiCr_{0.1}Mn_{1.9}O_4$의 화학확산계수는 $LiMn_2O_4$보다 약 10배 이상 크게 나타났다. 이러한 결과를 볼 때 $LiMn_2O_4$에 여러 가지 금속원소를 치환시킴으로 구조적인 안정화로 인한 전기화학적 성능을 향상시킬 수 있었다.

• 한국전기전자재료학회논문지
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• 제15권4호
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• pp.361-366
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• 2002

Spinel $LiMn_{2-y}M_yO_4$ and $LiMn_{2-y}M_yO_4$ (M=Mg, Zn) powders were synthesized by solid-state method at $800^{\circ}C$ for 37h. Crystal structure and electrochemical properties were analyzed by X-ray diffraction, charge-discharge test, cyclic voltammetry and ac impedance to $LiMn_{2-y}M_yO_4$. All cathode material showed spinel structure in X-ray diffraction. Ununiform distortion which calculated by (111) face and (222) face was almost constant in spite of the change of the kind and the substituting ratio of the metal cation in $LiMn_{2-y}M_yO_4$ (M=Mg, Zn). $LiMn_{1.9}Mg_{0.05}Zn_{0.05}O_4/Li$ cell substituted $Mg^{+2}$ and $Zn^{+2}$ showed excellent discharge capacities than other cells, which it presented about 120mAh/g at the 1st cycle and about 73mAh/g at the 250th cycle, respectively. AC impedance of $LiMn_{2-y}M_yO_4/Li$ cells showed the similar resistance of about 65~110$\Omega$ before cycling.

• 한국전기전자재료학회논문지
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• 제14권4호
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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.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.455-458
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• 2001

Spinel $LiMn_{2-y}$$M_{y}$ $O_4$powder was prepared solid-state method by calcining the mixture of LiOH - $H_2O$, Mn $O_2$, ZnO and MgO at 80$0^{\circ}C$ for 36h. To investigate the effect of substitution with Mg, Zn cation, charge-discharge experiments and initial impedance spectroscopy performed. The structure of $LiMn_{2-y}$$M_{y}$ $O_4$crystallites was analyzed from powder X-ray diffraction data as a cubic spinel, space group Fd3m. all cathode material showed spinel phase based on cubic phase in X-ray diffraction. Ununiform which calculated by (111) face and (222) face was constant in spite of the change of y value, except PUf\ulcorner LiM $n_2$ $O_4$. The discharge capacities of the cathode for the cation subbstitUtes $LiMn_{2-y}$$M_{y}$ $O_4$/Li cell at the 1st cycle and at the 40th cycle were about 120~124 and 108~112mAh/g except LiM $n_{1.9}$Z $n_{0.1}$ $O_4$/Li cell, respectively. This cell capacity is retained by 93% after 40th cycle. AC impedance of $LiMn_{2-y}$$M_{y}$ $O_4$/Li cells revealed the similar resistance of about 65~110$\Omega$ before cycling. before cycling.g.g.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 춘계학술대회 논문집 센서 박막재료
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• pp.18-22
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• 2001

Spinel $LiMn_{2-y}Mn_{y}O_4$ powder was prepared solid-state method by calcining the mixture of $LiOH{\cdot}H_2O$, $MnO_2$ and MgO at $800^{\circ}C$ for 36h. To investigate the effect of temperature for cycle behaviour of cathode material during cycling, charge-discharge experiments and initial impedance spectroscopy performed by the condition of the charge-discharge temperature. Initial charge-discharge capacity was gradually increased by rising charge-discharge temperature. However, capacity was suddenly decreased at high temperature during cycling. Capacity at low temperature was almost constant during cycling. It confirmed because Mn dissolution is more serious at high temperature than at low temperature.

• Journal of Electrochemical Science and Technology
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• 제4권3호
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• pp.102-107
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• 2013

The electrochemical properties of Mg-doped $LiFe_{0.48}Mn_{0.48}Mg_{0.04}PO_4$ and pure $LiFe_{0.5}Mn_{0.5}PO_4$ olivine cathodes are examined and the lattice parameters are refined by Rietveld analysis. The calculated atomic parameters from the refinement show that $Mg^{2+}$ doping has a significant effect in the olivine $LiFeMnPO_4$ structure. The unit cell volume is 297.053(2) ${\AA}^3$ for pure $LiFe_{0.5}Mn_{0.5}PO_4$ and is decreased to 296.177(1) ${\AA}^3$ for Mg-doped $LiFe_{0.48}Mn_{0.48}Mg_{0.04}PO_4$ sample. The doping of $Mg^{2+}$ cation with atomic radius smaller than $Mn^{2+}$ and $Fe^{2+}$ ion induces longer Li-O bond length in $LiO_6$ octahedra of the olivine structure. The larger interstitial sites in $LiO_6$ octahedra facilitate the lithium ion migration and also enhance the diffusion kinetics of olivine cathode material. The $LiFe_{0.48}Mn_{0.48}Mg_{0.04}PO_4$ sample with larger Li-O bond length delivers higher discharge capacities and also notably increases the rate capability of the electrode.

• 한국결정성장학회지
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• 제9권5호
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• pp.447-453
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• 1999

Czochralski법으로 congruent한 조성(48.6 mol% $LiNbO_2$)과 $LiNbO_3$: Mg(4.5, 6.0, 10.0, 20.0mol%), $LiNbO_3$ : Mn(0.1 mol%), $LiNbO_3$: Fe(0.05 mol%), $LiNbO_3$ : (Mg(4.5)+Mn(0.1), Fe(0.05 mol%)), LiNbO3 : (Mg(20.0)+Mn(0.1), Fe(0.05 mol%))인 융액으로부터 결정을 c-축 방향으로 성장시켰다. 이 결정들은 상온에서의 XRD pattern과 상온~$1230^{\circ}C$의 온도영역과 100Hz~10MHz의 주파수영역에서의 유전상수, 상온에서의 UV_VIS, IR 스펙트럼, 결정내의 Mn2+, Fe3+ 이온에 대한 ESR 스펙트럼 등을 측정하였는데 XRD pattern과 상전이 온도, UV 흡수단, OH- 이온에 의한 스펙트럼, ESR 스펙트럼 등의 Mg첨가량 의존성으로부터 Mg가 첨가된 $LiNbO_3$ 결정의 결함구조에 대해서 논의하였다. congruent한 $LiNbO_3$결정과 Mg를 첨가한 $LiNbO_3$ 결정에서의 Mn2+ 이온은 Mg의 첨가량에 관계없이 Li+을 치환한다. 그러나 congruent한 $LiNbO_3$ 결정과 Mg를 첨가한 $LiNbO_3$ 결정에서의 Fe3+ 이온은 Mg가 4.5 mol% 첨가된 결정에서는 Li+ 자리를 Mg가 6.0 mol% 이상 첨가된 결정에서는 {{{{ { Nb}`_{Li } ^{5+ } }}}} 자리를 치환한다.

• 한국전기전자재료학회논문지
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• 제14권8호
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• pp.663-669
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• 2001

Spinel LiM $n_2$ $O_4$ and LiM $n_{1.9}$M $g_{0.1}$ $O_4$ power was synthesized with solid-state method by calcining the mixture of LiOH.$H_2O$, Mn $O_2$ and MgO at 80$0^{\circ}C$ for 36 h in an air atmosphere. To investigate the effect of temperature on he cycle performance of cathode material during cycling, charge-discharge experiments and ac impedance measurement were performed. Initial discharge capacity was gradually increased with the increase of charge-discharge temperature. Discharge capacity at high temperature was suddenly decreased during cycling. On the other hand, discharge capacity at low temperature was almost constant during cycling. It confirmed that Mn dissolution is serious at high temperature than at low temperature. LiM $n_2$ $O_4$ and LiM $n_{1.9}$M $g_{0.1}$ $O_4$ showed the best capacity and stability at room temperature.ure.ure.