• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.11a
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• pp.25-28
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• 1998

Lithiated cobalt and nickel oxides are becoming very attractive as active cathode materials for secondary lithium ion secondary battery. $LiCoO_2$ is easily synthesized from lithium cobalt salts, but has a relatively high oxidizing potential on charge. LiNiOz is synthesized by a more complex procedure and its nonstoichiometry significantly degraded the charge-discharge characteristics. But $LiNiO_2$ has a lower charge potential which increases the system stability. Lithiated cobalt and nickel oxides are iso-structure which make the preparation of solid solutions of $LiNi_{1-x}Co_xO_2$ for O$LiCoO_2 and LiNiO_2$ electrode. The aim of the presentb paper is to study the electrochemical behaviour, as weU as the possibilities for practical application of layered Iithiated nickel oxide stabilized by $Co^{3+}$ substitution as active cathode materials in lithium ion secondary battery.

• Journal of the Korean Ceramic Society
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• v.37 no.5
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• pp.466-472
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• 2000

As cathode materials of LiMn2O4-based lithium-ion secondary batteries, Li(Mn1-$\delta$M$\delta$)2O4 (M=Ni and Co, $\delta$=0, 0.05, 0.1 and 0.2) materials which Co and Ni are substituted for Mn, were syntehsized by the solid state reaction at 80$0^{\circ}C$ for 48 hours. No second phases were formed in Li(Mn1-$\delta$M$\delta$)2O4 system with substitution of Co. However, substitution of Ni caued to form a second phase of NiO when its composition exceeded over 0.2 of $\delta$ in Li(Mn1-$\delta$M$\delta$)2O4. As the results of charging-discharging test, the maximum capacity of Li(Mn1-$\delta$M$\delta$)2O4 appeared in $\delta$=0.1 for both Co and Ni. Also, Li(Mn1-$\delta$M$\delta$)2O4 electrode showed higher capacity and better cycle performance than LiMn2O4.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.348-349
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• 2006

$LiNi_{1/3}Mn_{1/3}Co_{1/3}O_2$ cathode material was synthesized by a mixed hydroxide methode. The surface of the $LiNi_{1/3}Mn_{1/3}Co_{1/3}O_2$ was coated with a carbon by using a sol-gel method to improve further its electrochemical properties. Electrochemical studies were performed by assembling 2032 coin cells with lithium metal as an anode. OSC (differential scanning calorimetry) data showed that exothermic reactions of charged to 4.3V vs. Li was suppressed in the carbon-coated materials. The carbon-coated $LiNi_{1/3}Mn_{1/3}Co_{1/3}O_2$ showed the improved rate capability and thermal stability.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.1
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• pp.64-70
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• 2006

In this study, the $LiCoO_2/LiNi_{1/3}Mn_{1/3}Co_{1/3}O_2$ mixed cathode electrodes were prepared and their electrochemical performances were measured in a high cut-off voltage. As the content of $LiNi_{1/3}Mn_{1/3}Co_{1/3}O_2$ increased in a mixed cathode, the reversible specific capacity and cycleability of the electrode enhanced, but the rate capability was deteriorated. On the contrary the rate capability of the cathode enhanced, but the reversible specific capacity and cycleability were deteriorated, increasing the content of $LiCoO_2$ in the mixed cathode. The cell of $LiCoO_2/LiNi_{1/3}Mn_{1/3}Co_{1/3}O_2$ ($50:50 wt\%$) mixed cathode delivered a discharge capacity of ca. 168 mAh/g at a 0.2 C rate. The capacity of the cell decreased with the current rate and a useful capacity of ca. 152 mAh/g was obtained at a 2.0 C rate. However, the cell showed very stable cycleability: the discharge capacity of the cell after 20th charge/discharge cycling maintains ca. 163 mAh/g.

• Journal of Electrochemical Science and Technology
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• v.3 no.1
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• pp.29-34
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• 2012

The structural changes of $Li_{1-x}Ni_{0.5}Co_{0.2}Mn_{0.3}O_2$ cathode material for lithium ion battery during the first charge was investigated in comparison with $Li_{1-x}Ni_{0.8}Co_{0.15}Al_{0.05}O_2$ using a synchrotron based in situ X-ray diffraction technique. The structural changes of these two cathode materials show similar trend during first charge: an expansion along the c-axis of the unit cell with contractions along the a- and b-axis during the early stage of charge and a major contraction along the c-axis with slight expansions along the a- and b-axis near the end of charge at high voltage limit. In $Li_{1-x}Ni_{0.5}Co_{0.2}Mn_{0.3}O_2$ cathode, however, the initial unit cell volume of H2 phase is bigger than that of H1 phase since the c-axis undergo large expansion while a- and b- axis shrink slightly. The change in the unit cell volume for $Li_{1-x}Ni_{0.5}Co_{0.2}Mn_{0.3}O_2$ during charge is smaller than that of $Li_{1-x}Ni_{0.8}Co_{0.15}Al_{0.05}O_2$. This smaller change in unit cell volume may give the $Li_{1-x}Ni_{0.5}Co_{0.2}Mn_{0.3}O_2$ cathode material a better structural reversibility for a long cycling life.

• Bulletin of the Korean Chemical Society
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• v.22 no.12
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• pp.1328-1332
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• 2001

The structure and electrochemical properties of the LixCoyNi1-yO2 (y=0.1, 0.3, 0.5, 0.7, 1.0) system synthesized by solid state reaction with various starting materials have been investigated to optimize the characteristics and synthetic conditions of the LixCoyNi1-yO2. The first discharge capacities of LixCoyNi1-yO2 are 60 mAh/g-180 mAh/g with synthetic conditions. Among them, the LixNi0.7Co0.3O2, which was prepared with LiOH, NiO, and Co3O4 at $850^{\circ}C$, had the best electrochemical properties. The first discharge capacity of the compound was 180 mAh/g.

• Journal of the Korean Ceramic Society
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• v.38 no.6
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• pp.515-521
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• 2001

출발 물질로서 L $i_2$C $O_3$, NiC $O_3$, CoC $O_3$를 사용하고 조성과 합성 온도를 변화시켜, 고온 고상법에 의하여 LiN $i_{1-y}$ $Co_{y}$ $O_2$(y=0.1, 0.3, 0.5)를 합성하였다. 합성과 시료들의 결정구조, 미세구조 그리고 전기화학적 특성을 조사하였다. 80$0^{\circ}C$와 8$50^{\circ}C$에서 제조한 L $i_{x}$N $i_{1-y}$ $Co_{y}$ $O_2$는, 삼방정계(space group: R3m)의 $\alpha$-NaFe $O_2$구조로 결정화되어 있는 층상 구조를 형성하였다. LiN $i_{1-y}$ $Co_{y}$ $O_2$(y=0.1, 0.3, 0.5)는 Co의 양이 증가함에 따라 a축과 c축의 크기가 감소하였는데, 이는 코발트 이온의 크기가 니켈 이온의 크기보다 작은데 기인하는 것이다. 그러나 c축과 a축의 크기의 비(c/a)가 증가하였음은 이차원적 구조가 잘 발달됨을 보여준다. 니켈에 대한 코발트의 치환량에 따른 리튬 이온의 삽입/추출 가역성은 코발트의 치환량이 증가하면서 증가하여 y=0.3인 LiN $i_{0.9}$ $Co_{0.1}$ $O_2$에서 대체로 우수하였고 그 이상으로 y값이 증가하면 가역성이 나빠졌다. 80$0^{\circ}C$에서 합성한 LiN $i_{0.9}$ $Co_{0.1}$ $O_2$가 가장 큰 초기 방전 용량 146 mAh/g을 나타내었으며, 싸이클링 성능도 비교적 우수하였다. 8$50^{\circ}C$에서 합성한 LiN $i_{0.9}$ $Co_{0.1}$ $O_2$와 LiN $i_{0.7}$ $Co_{0.3}$ $O_2$가 우수한 싸이클링 성능을 보였다.다. 싸이클링 성능을 보였다.다.보였다.다.

• Journal of the Korean Electrochemical Society
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• v.11 no.3
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• pp.197-210
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• 2008

The cathode materials for lithium ion battery have been developed in accordance with the battery performance. $LiCoO_2$ initially adapted at lithium ion battery is going to be useful even at the charging voltage of 4.3 V by surface treatment or doping which drastically improved the performance of $LiCoO_2$. On the other hand, the complicate and multiple functions of recent electronic equipments required higher operational voltage and higher capacity than ever, which is going to be driving force for developing new cathode materials. Some of them are $LiNi_{1-x}{M_xO_2}$, $Li[Ni_{x}Mn_{y}Co_{z}]O_{2}$, $Li[{Ni}_{1/2}{Mn}_{1/2}]O_{2}$. Other new type of cathode materials having high safety is also developed to apply for HEV (hybrid electrical vehicle) and power tool applications. ${LiMn}_{2}{O}_{4}$ and $LiFePO_4$ are famous for highly stable material, which are expected to give contribution to make safer battery. In near future, the various materials having both capacity and safety will be developed by new technology, such as solid solution composite.

• Journal of the Korean Chemical Society
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• v.66 no.6
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• pp.451-458
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• 2022

Through the crystal alignment research based on the magnetic properties of LiNi_xMn_yCo_1-(x+y)O₂ such as magnetic susceptibility and related anisotropy, a crystal aligned LiNi_0.6Mn_0.2Co_0.2O₂ electrode is obtained, in which the (00l) plane is frequently oriented perpendicular to the surface of a current collector. The crystal aligned LiNi_0.6Mn_0.2Co_0.2O₂ electrode steadily exhibits low electrode polarization properties during the charge/discharge process in a lithium-ion battery, thus affording an improved capacity compared to a pristine LiNi_0.6Mn_0.2Co_0.2O₂ electrode. The aligned LiNi_0.6Mn_0.2Co_0.2O₂ electrode may have an appropriate structural nature for fast lithium-ion transport due to the oriented (00l) plane, and thus it contributes to enhancing the battery performance. This enhancement is analyzed in terms of various electrochemical theories and experiment results; thus, it is verified to occur because of the considerably fast lithium-ion transport in the aligned LiNi_0.6Mn_0.2Co_0.2O₂ electrode.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.5
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• pp.443-449
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• 2007

The structural and thermal stability of $Li[Co_{0.1}Ni_{0.15}Li_{0.2}Mn_{0.55}]O_2$ electrode during cycling process was studied. The sample was prepared by simple combustion method. Although there were irreversible changes on the initial cycle, O3 stacking for $Li[Co_{0.1}Ni_{0.15}Li_{0.2}Mn_{0.55}]O_2$ structure was retained during the first and subsequent cycling process. Impedance of the test cell was decreased after the first charge-discharge process, which would be of benefit to intercalation and deintercalation of lithium ion on subsequent cycling. As expected, cycling test for 75 times increased impedance of the cell a little, instead, thermal stability of $Li[Co_{0.1}Ni_{0.15}Li_{0.2}Mn_{0.55}]O_2$ was improved. Moreover, based on DSC analysis, the initial exothermic peak was shifted to high temperature range and the amount of heat was also decreased after cycling test, which displayed that thermal stability was not deteriorated during cycling.