• 한국산학기술학회논문지
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• 제1권1호
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• pp.27-32
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• 2000

인산염계 Ag₂OㆍLi₂OㆍCaOㆍTiO₂ㆍP₂O/sub 5/ 조성에 CuO를 0.05∼l.5 mole 첨가하여 다공성 글래스 세라믹스를 제조하였으며. 제조된 모유리는 최적 핵형성을 위해 610℃. 최고 결정성장을 위해 840℃에서 열처리하였다. 1N-HC1에서 β-Ca₃(PO₄)결정상만을 선택적으로 용출하였으며 LiTi₂(PO₄)₃상과 AgTi₂(PO₄)₃결정상이 존재하는 Glass Ceramics를 제조하였다. 다공성 글래스 세라믹스의 항균효과 및 특성을 평가하였다. Staphylococcus aureus와 Salmonella typhi 균이 본 연구에 사용되었으며, 탁월한 항균효과를 나타내는 것으로 평가되었다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 하계종합학술대회 논문집
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• pp.319-322
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• 1999

In this paper, we report characteristics of a internal chip of LiNbO$_3$ modulator with low-driving-voltage at 150nm wavelength. A Ti diffusion method for LiNbO$_3$ optical waveguide and a buffer layer for improving phase velocity mismatch between optical and microwave waves were employed. The traveling-wave coplanar waveguide electrode of 35mm is used for reducing the driving voltage. From this work, wideband modulation of 10㎓ and low-driving voltage of 3.9volts are realized.

• Bulletin of the Korean Chemical Society
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• 제33권7호
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• pp.2315-2319
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• 2012

To improve the performance of $LiFePO_4F$, a novel sol-gel process is developed. For comparison, ceramic process is also implemented. From X-ray diffraction results we know that each sample adopts a triclinic $P{\bar{1}}$ space group, and they are isostructural with amblygonite and tavorite. The scanning electron microscope images show that the homogeneous grains with the dimension of 300-500 nm is obtained by the sol-gel process; meanwhile the sample particles obtained by ceramic process are as big as 1000-3000 nm. By galvanostatic tests and at electrochemical impedance spectroscopy method, the sample obtained by sol-gel process presents better electrochemical properties than the one obtained by ceramic process.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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• pp.350-351
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• 2007

The $LiFePO_4$ as cathode materials for lithium ion batteries was synthesized by the solid-state reaction using ballmiller and employed one step heat treatment at $650^{\circ}C$. The influence of the heating time on the structure, particle size and cycle performance was investigated. $LiFePO_4$ heated at $650^{\circ}C$ for 3 h exhibited higher discharge capacity of 140 mAh/g and excellent cycle performance.

• 한국세라믹학회:학술대회논문집
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• 한국세라믹학회 2003년도 추계총회 및 연구발표회 초록집
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• pp.200.2-200
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• 2003

• 전기화학회지
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• 제13권3호
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• pp.157-162
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• 2010

The electrodes comprising nano-sized $LiFePO_4$, carbon black and binder are prepared with two different Al current collectors. One is the generally used normal Al foil and the other is the chemically etched Al foil. Surface characteristics of each Al foil and electrochemical performance of the cathodes using each foil are investigated. The electrode from the etched Al foil exhibits better physical and electrochemical properties as compared to those of the normal Al foil because the etched Al foil has rough surface with sub-micron pores which improve the adhesion between the electrode materials and the substrate. The electrode on the etched Al foil has such a strong peel strength that the impedance is smaller than that of normal one. Indeed the $LiFePO_4$ electrode from the etched Al foil exhibits a better rate capability and remains intact even after storage for 1 week at the charged state at the elevated temperature $60^{\circ}C$.

• Bulletin of the Korean Chemical Society
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• 제29권9호
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• pp.1737-1741
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• 2008

The electrochemical and thermal stability of $LiNi_{0.8}Co_{0.16}Al_{0.04}O_2$ were studied before and after $Co_3(PO_4)_2$ coating. Different to conventional coating material such as $ZrO_2$ or AlPO4, the coating layer was not detected clearly by TEM analysis, indicating that the $Co_3(PO_4)_2$ nanoparticles effectively reacted with surface impurities such as $Li_2CO_3$. The coated sample showed similar capacity at a low C rate condition. However, the rate capability was significantly improved by the coating effect. It is associated with a decrease of impedance after coating because impedance can act as a major barrier for overall cell performances in high C rate cycling. In the DSC profile of the charged sample, exothermic peaks were shifted to high temperatures and heat generation was reduced after coating, indicating the thermal reaction between electrode and electrolyte was sucessfully suppressed by $Co_3(PO_4)_2$ nanoparticle coating.

• Journal of Electrochemical Science and Technology
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• 제14권4호
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• pp.320-325
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• 2023

In Li-ion batteries, a thick electrode is advantageous for lowering the inactive current collector portion and obtaining a high energy density. One of the critical failure mechanisms of thick electrodes is inhomogeneous lithiation and delithiation owing to the axial location of the electrode. In this study, it was confirmed that the top layer of the composite electrode contributes more to the charging step owing to the high ionic transport from the electrolyte. A high-loading multilayered electrode containing LiFePO₄ (LFP) and LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811) was developed to overcome the inhomogeneous electrochemical reactions in the electrode. The electrode laminated with LFP on the top and NCM811 on the bottom showed superior cyclability compared to the electrode having the reverse stacking order or thoroughly mixed. This improvement is attributed to the structural and interfacial stability of LFP on top of the thick electrode in an electrochemically harsh environment.

• 한국수소및신에너지학회논문집
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• 제22권5호
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• pp.728-734
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• 2011

$LiFePO_4$ is a promising cathode material for secondary lithium batteries due to its high energy density, low cost and safety. $LiFePO_4$ was synthesized by the citrate process under reductive, neutral, and oxidative, atmospheres and the crystal structure was analyzed by X-ray powder diffraction. The samples synthesized under $N_2$ and $H_2$ atmosphere showed a single phase of a olivine structure, where the samples synthesized under $O_2$ atmosphere exhibited second phase of $Fe2O_3$. All the samples synthesized at 400, 600 and $800^{\circ}C$ under $N_2$ atmosphere presented a single phase of olivine. Residual organic material was observed for the sample synthesized at $400^{\circ}C$. There was nearly no intensity difference between the samples synthesized at $600^{\circ}C$ and $800^{\circ}C$. The electrochemical characteristic of the $LiFePO_4$ synthesized at $600^{\circ}C$ in the $N_2$ atmosphere was analyzed. The result exhibited an high discharge capacity of 160 mAh/g at the first cycle, and 155-160 mAh/g after 45 cycles.

• 한국재료학회지
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• 제19권4호
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• pp.220-223
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• 2009

Lithium dihydrogen phosphate ($LiH_2PO_4$) powder was purchased from Aldrich Chemical Co. From the scanning electron microscope (SEM) observation, these polycrystals have dimensions in the range of $25-250{\mu}m$. The electrical conductivity was measured at a measuring frequency of 1 kHz on heating polycrystalline lithium dihydrogen phosphate ($LiH_2PO_4$) from room temperature to 493 K. Two anomalies appeared at 451 K ($T_{p1}$) and 469 K ($T_{p2}$). The electrical conductivity reached the magnitude of the superprotonic phases: $3{\times}10^{-2}{\Omega}^{-1}cm^{-1}$ at 451 K ($T_{p1}$) and $1.2{\times}10{\Omega}^{-1}cm^{-1}$ at 469 K ($T_{p2}$). It is uncertain whether the superprotonic phase transformations are due to polymorphic transitions in the bulk, surface transitions, or chemical reactions (thermal decomposition) at the surface. Considering several previous thermal studies (differential scanning calorimetry and thermogravimetry), our experimental results seem to be related to the last case: chemical reactions (thermal decomposition) at the surface with the progressive solid-state polymerization.