• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.241-242
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• 2006

In this work, the $LiFePO_4-LiCoO_2$ mixed cathode electrodes were prepared and their electrochemical performances were measured in different current density. The cell of $LiFePO_4-LiCoO_2$ observed two voltage plateau regions at 3.4 and 3.9V. The cell of $LiFePO_4-LiCoO_2$ (90:10 wt%) mixed cathode delivered a discharge capacity of ca. 139.8 mAh/g at a 0.2C rate. The capacity of the cell decreased with the current rate and a useful capacity of ca 85.7mAh/g was obtained at a 2C rate.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.5
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• pp.298-302
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• 2016

In this work, $LiMn_2O_4$ and $LiNi_{1/3}Mn_{1/3}Co_{1/3}O_2$ cathode materials are mixed by some specific ratios to enhance the practical capacity, energy density and cycle performance of battery. At present, the most used cathode material in lithium ion batteries for EVs is spinel structure-type $LiMn_2O_4$. $LiMn_2O_4$ has advantages of high average voltage, excellent safety, environmental friendliness, and low cost. However, due to the low rechargeable capacity (120 mAh/g), it can not meet the requirement of high energy density for the EVs, resulting in limiting its development. The battery of $LiMn_2O_4-LiNi_{1/3}Mn_{1/3}Co_{1/3}O_2$ (50:50 wt%) mixed cathode delivers a energy density of 483.5 mWh/g at a current rate of 1.0 C. The accumulated capacity from $1^{st}$ to 150th cycles was 18.1 Ah/g when the battery is cycled at a current rate of 1.0 C in voltage range of 3.2~4.3 V.

• Journal of Electrochemical Science and Technology
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• v.3 no.2
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• pp.63-67
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• 2012

We prepared various $LiNi_{0.8}Co_{0.15}Al_{0.05}O_2-LiFePO_4$ mixed-cathode electrodes by changing the content of $LiNi_{0.8}Co_{0.15}Al_{0.05}O_2$ and $LiFePO_4$ used, and we analyzed the electrochemical characteristics of the cathodes. We found that the reversible specific capacity of the cathodes increased and that the capacity retention ratios of the cathodes decreased during cycling as the content of $LiNi_{0.8}Co_{0.15}Al_{0.05}O_2$ increased. Conversely, we found that although the reversible specific capacity of the cathodes decreased because of the material composition, the cycle property of the cathodes increased when the $LiFePO_4$ content increased. We analyzed the thermal stability of the $LiNi_{0.8}Co_{0.15}Al_{0.05}O_2-LiFePO_4$ mixed-material cathodes by differential scanning calorimetry and found that it increased as the $LiFePO_4$ content increased.

• Journal of Hydrogen and New Energy
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• v.24 no.2
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• pp.186-192
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• 2013

In order to reduce the costs and to improve the durability of solid oxide fuel cell (SOFC), the operating temperature should be decreased while the power density is maintained as much as possible. However, lowering the operating temperature increases the cathode interfacial polarization resistances dramatically, limiting the performance of low-temperature SOFC at especially purely electronic conducting cathode. To improve cathode performance at low temperature, the number of reaction sites for the oxygen reduction should be increased by using a mixed ionic and electronic conducting (MIEC) material. In this study, anode-supported fuel cells with two different thicknesses of the MIEC cathode were fabricated and tested at various operating temperatures. The anode supported cell with $32.5{\mu}m$-thick BSCFZn-LSCF cathode layer showed much lower polarization resistance than that with $3.2{\mu}m$ thick cahtode and higher power density especially at low temperature. The effects of cathode layer thickness on the electrochemical performance are discussed with analysis of impedance spectra.

• 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.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.11a
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• pp.383-386
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• 1999

The importance of rechargeable lithium cells has been emphasized. So a large variety of materials has been discovered and evaluated for use as reversible cathodes and electroyltes. This paper examines the charge/discharge properties and the charge/discharge cycling life of Li$_2$O-P$_2$O-V$_2$O$_{5}$Li cells. In audition, DTA tests were carried out on Li$_2$O-P$_2$O-V$_2$O$_{5}$ glass. As a result the best performance was achieved when 0.3Li$_2$O-0.1P$_2$O$_{5}$-0.6V$_2$O$_{5}$Li cells was mixed with SP270. that is discharge capacity of 240mAh/g have been achieved. In addition this battery exhibited good cycling performance. Considering these results we expected utilization of the Li$_2$O-P$_2$O-V$_2$O$_{5}$ glass as a cathode material in a secondary battery.y battery.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.318-319
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• 2005

본 연구에서는 $LiCoO_2/LiNi_{1/3}Mn_{1/3}Co_{1/3}O_2$ 혼합 정극활물질로 사용하여 전극을 제작하고 성능을 평가하였다. $LiCoO_2/LiNi_{1/3}Mn_{1/3}Co_{1/3}O_2$와 $LiCoO_2$의 혼합비에 따른 충방전 거동 및 임피던스 변화를 측정하였다. 각 조성에서의 초기용량은 160 ~ 170 mAh/g 정도였으며, $LiNi_{1/3}Mn_{1/3}Co_{1/3}O_2$의 첨가 비율이 증가함에 따라 비용량이 증가하였으나 고율에서의 방전용량은 낮았다.

• Journal of the Korean Ceramic Society
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• v.51 no.1
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• pp.51-56
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• 2014

Mixed ionic and electronic conducting $K_2NiF_4$-type oxide, $Nd_{2-x}Sr_xNiO_{4+\delta}$ (x = 0, 0.4, 0.6) powders were synthesized by a solid-state reaction technique and solid oxide fuel cells consisting of a $Nd_{2-x}Sr_xNiO_{4+\delta}-GDC$ cathode, a Ni-YSZ anode and 8YSZ as an electrolyte were fabricated. The effect of strontium substitution for neodymium on the electrical and electrochemical properties was examined. The electrical conductivity increased with an increase in the Sr doping content, while it appears that the excess oxygen (${\delta}$) decreased. Sr doping into $Nd_2NiO_{4+\delta}$ resulted in an increase in the cathode polarization resistance and an decrease in the power density of the cell. These phenomena may be associated with the decreased amount of excess oxygen noted in the $Nd_{2-x}Sr_xNiO_{4+\delta}$ cathode.

• The Korean Journal of Ceramics
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• v.5 no.3
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• pp.250-254
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• 1999

Synthesis of the spinel $LiMn_2O_4$ by emulsion method was investigated. $LiOH.H_2O \;and \;Mn(NO_3)_2.6H_2O$ were used as starting materials to prepare mixed aqueous solution (0.5 mol/$\ell$ for the $LiMn_2O_4$). Kerosene, paraffin oil and span 80 were used for organic phase. The aqueous solutioin and organic phase were mixed in the ratio of 2:1 and emulsified at the speed of 4000 rpm for 5 min. The prepared emulsions were dropped into the petroleum heated at $170^{\circ}C$ to evaporate water in the silicon oil bath, dried at $120^{\circ}C$ in the oven the remove petroleum and calcined at temperature ranges from 600 to $900^{\circ}C$ for 48 hrs. The characteristics of powders were investigated by XRD, SEM, BET and electrochemical properties of synthesized cathode materials were measured with Galvanostatic system. $Li_{1.05}Mn_2O_4$ calcined at $800^{\circ}C$ for 48 hrs showed initial discharge capacity of 125.9mAH/g.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.04a
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• pp.31-32
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• 2008

The structure of OLEDs with conventional heterostructure consists of anode, hole injection layer, hole transport layer, light-emitting layer, electron transport layer, electron injection layer, and cathode. NPB used as a hole transport layer and DPVBi used as a blue light emitting layer were graded-mixed at selected ratio. Interface at heterojunction between the hole transport layer and the elecrtron transport layer restricts device's stability. Mixing of the hole transport layerand the emitting layer removes abrupt interface between the hole transport. layer and the electron transport layer. The stability of OLED with graded mixed-layer developed in this study was improved.