• 생물환경조절학회지
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• 제4권2호
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• pp.188-194
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• 1995

야마자키 토마토용 배양액을 이용하여 토마토를 담액 재배할 경우, pH 7.5 정도인 수돗물을 용수로 한 배양액에 NH$_4$H$_2$PO$_4$를 사용하므로써 배양액의 pH를 안정시키는 동시에, 적정 식물생장을 유도할 수 있는 NH$_4$H$_2$PO$_4$농도를 찾고자 실험을 수행하였다. 그 결과 NH$_4$H$_2$PO$_4$의 농도를 증가시킴에 따라 배양액의 pH가 감소하는 경향을 보였으며, EC는 반대의 경향을 보였다. NH$_4$-N 8/3 me/$\ell$ 처리구에서는 식물체에 황화현상이 나타났다. NH$_4$-N이 4/3 me/$\ell$ 혹은 5/3 me/$\ell$인 처리구에서 pH와 EC를 안정적으로 유지할 수 있었다. 엽장이나 줄기직경은 NH$_4$-N 2/3 me/$\ell$처리구에서 큰 값을 나타냈고, 과실의 당도는 NH$_4$-N 5/3 me/$\ell$ 처리구에서 가장 높았다. 이상의 결과로부터, 토마토의 담액 재배시 수확기 이전에는 NH$_4$-N을 2/3 me/$\ell$로 하고, 수확기에는 NH$_4$-N을 4/3-5/3 me/$\ell$로 하는 것이 바람직한 것으로 사료되었다.

• 전기화학회지
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• 제13권4호
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• pp.246-250
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• 2010

In this study, nano-crystallized $Al_2O_3$ was coated on the surface of $LiFePO_4$ powders via a novel dry coating method. The influence of coated $LiFePO_4$ upon electrochemical behavior was discussed. Surface morphology characterization was achieved by transmission electron microscopy (TEM), clearly showing nano-crystallized $Al_2O_3$ on $LiFePO_4$ surfaces. Furthermore, it revealed that the $Al_2O_3$-coated $LiFePO_4$ cathode exhibited a distinct surface morphology. It was also found that the $Al_2O_3$ coating reduces capacity fading especially at high charge/discharge rates. Results from the cyclic voltammogram measurements (2.5-4.2 V) showed a significant decrease in both interfacial resistance and cathode polarization. This behavior implies that $Al_2O_3$ can prevent structural change of $LiFePO_4$ or reaction with the electrolyte on cycling. In addition, the $Al_2O_3$ coated $LiFePO_4$ compound showed highly improved area-specific impedance (ASI), an important measure of battery performance. From the correlation between these characteristics of bare and coated $LiFePO_4$, the role of $Al_2O_3$ coating played on the electrochemical performance of $LiFePO_4$ was probed.

• 전기화학회지
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• 제15권2호
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• pp.101-108
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• 2012

본 연구에서는 탄소를 첨가하여 $Li_3V_2(PO_4){_3}$의 낮은 전기전도도를 개선시켜서 고율 방전특성, 충 방전 사이클 특성을 향상시키는 것을 목적으로 하고 있다. 탄소 첨가제로는 글루코스와 CNT (carbon nano tube)를 사용하였으며, 탄소의 첨가 여부와 탄소 원료의 종류에 따라 합성된 $Li_3V_2(PO_4){_3}$의 구조적 그리고 전기화학적 특성에 대해 연구를 하였다. $Li_3V_2(PO_4){_3}$와 $Li_3V_2(PO_4){_3}$/C의 $Li_3V_2(PO_4){_3}$/CNT의 합성방법으로는 고상법을 이용하였다. 합성된 물질을 수소환원방법을 통하여 600, 700, 800, $900^{\circ}C$에서 소성해주었다. 합성된 물질로 양극 집전판을 제작하여 상대전극을 리튬메탈로 한 Coin 2032 cell을 만들어 전기화학적 특성분석을 진행하였다. 전지테스트는 정전류법을 이용하여 3.0~4.8 V까지 충 방전 실험을 하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 추계학술대회 논문집
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• pp.132-132
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• 2009

Phospho-olivine $LiFePO_4$ cathode materials were prepared by hydrothermal reaction. In this study, Multi-walled carbon nanotube (MWCNT) and Carbon black was added to enhance the electrical conductivity of $LiFePO_4$. $LiFePO_4$, $LiFePO_4$-MWCNT and $LiFePO_4$-C particles were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM) transmission electron microscope (TEM). $LiFePO_4/SPE/Li$, $LiFePO_4$-MWCMT/SPE/Li and $LiFePO_4$-C/SPE/Li cells were characterized electrochemically by charge/discharge experiments at a constant current density of $0.1mA\;cm^{-2}$ in a range between 2.5 and 4.3 V vs. $Li/Li^+$ and cyclic voltammetry (CV).

• 한국전기전자재료학회논문지
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• 제19권6호
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• pp.519-523
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• 2006

$LiFePO_4$ has been received attention as a potential cathode material for the lithium secondary batteries. In our study, $LiFePO_4$ cathode active materials were synthesized by a solid-state reaction. It was modified by coating $TiO_2$ and carbon in order to enhance cyclic performance and electronic conductivity. $TiO_2$ and carbon coatings on $LiFePO_4$ materials enhanced the electronic conductivity and its charge/discharge capacity. For lithium polymer battery applications, $LiFePO_4$/solid polymer electrolyte (SPE)/Li and $LiFePO_{4}-TiO_{2}/SPE/Li$ cells were characterized by a cyclic voltammetry and charge/discharge cycling. The electrode with $LiFePO_{4}-carbon-TiO_{2}$ in PVDF-PC-EC-$LiClO_{4}$ electrolyte showed promising capacity of above 100 mAh/g at 1C rate.

• Transactions on Electrical and Electronic Materials
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• 제8권1호
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• pp.41-45
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• 2007

Phospho-olivine $LiFePO_4$ cathode materials were prepared by hydrothermal reaction. Carbon black was added to enhance the electrical conductivity of $LiFePO_4$. The structural and morphological performance of $LiFePO_4$ and $LiFePO_4$-C powders were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). $LiFePO_4$/Li and $LiFePO_4$-C/Li cells were characterized electrochemically by cyclic voltammogram (CV), charge/discharge experiments and ac impedance spectroscopy. The results showed that the discharge capacity of $LiFePO_4$/Li cell was 147 mAh/g at the first cycle and 118 mAh/g after 30 cycles, respectively. The discharge capacity of $LiFePO_4$-C/Li cell with 5 wt% carbon black was the largest among $LiFePO_4$-C/Li cells, 133 mAh/g at the first cycle and 128 mAh/g after 30 cycles, respectively. It was demonstrated that cycling performance of $LiFePO_4$-C/Li cell with 5 wt% carbon black was better than that of $LiFePO_4$/Li cell.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 추계학술대회 논문집 광주전남지부
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• pp.48-52
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• 2006

Phospho-olivine $LiFePO_4$ cathode materials were prepared by hydrothermal reaction. Carbon black was added to enhance the electrical conductivity' of $LiFePO_4$. The structural and morphological performance of $LiFePO_4$ and $LiFePO_4$-C powders were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). $LiFePO_4$/Li and $LiFePO_4-C$/Li cells were characterized electrochemically by cyclic voltammogram (CV), charge/discharge experiments and ac impedance spectroscopy. The results showed that the discharge capacity of $LiFePO_4$/Li cell was 147 mAh/g at the first cycle and 118 mAh/g after 30 cycles, respectively. The discharge capacity of $LiFePO_4-C$/Li cell with 5wt% carbon black was the largest among $LiFePO_4-C$/Li cells, 133 mAh/g at the first cycle and 128 mAh/g after 30 cycles, respectively. It was demonstrated that cycling performance of $LiFePO_4-C$/Li cell with 5wt% carbon black was better than that of $LiFePO_4$/Li cell.

• 마이크로전자및패키징학회지
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• 제26권4호
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• pp.83-88
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• 2019

화학양론적 조성과 비화학양론적 조성을 갖는 LiBaPO₄:Eu²⁺ 계 형광체를 고상반응으로 제조한 후 환원 분위기에서 열처리한 다음 분말의 결정구조와 광 특성을 X선 회절 분석과 발광 분석을 통하여 조사하였다. XRD 분석 결과, 900℃에서 중간상으로서 Ba₃(PO₄)₂ 상이 주 결정상 LiBaPO₄와 함께 나타났다. 1,100℃에서 낮은 농도의 유로피움이 도핑된 조성의 결정구조는 삼방정(trigonal) 구조에 속하는 반면, 4 mol% Eu²⁺ 이상의 조성에서는 단사정(monoclinic) 계를 나타내었다. 4 mol% 이상의 Eu²⁺이 첨가된 비화학양론적 조성에서는 단일상의 LiBaPO₄가 형성되었다. 단일상의 LiBaPO₄:Eu²⁺ 계 형광체는 480nm에서의 청록색 발광스펙트럼을 나타내었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
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• pp.368-369
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• 2006

The pure $LiFePO_4$, carbon added $LiFePO_4(LiFePO_4/C$) and pyrene added $LiFePO_4(LiFePO_4/P$) are synthesized by using solid-state reaction. XRD patterns show no impurity phase in the three kinds of the cathode materials. The 10wt% pyrene added $LiFePO_4$ shows around 140mAh/g of discharge capacity at 3rd cycle compared to the pure $LiFePO_4$. The carbon added $LiFePO_4$ shows 145mAh/g of discharge capacity at 3rd cycle and stable cycle-life compared to the others.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 춘계학술대회 논문집
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• pp.5-9
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• 2005

$LiFePO_4$ is a potential candidate for the cathode material of the lithium polymer batteries. $LiFePO_4$ cathode active materials were synthesized by coating on the $LiFePO_4$ was tried using $TiO_2$ and corbon in oreder to increase cyclic performance and electronic conductivity. Highly dispersed on the particles enhances the electronic conductivity and increases the capacity. For lithium polymer battery applications, $LiFePO_4$/SPE/Li and $LiFePO_4$-$TiO_2$/SPE/Li 'cells were characterized electrochemically by cyclic volatammetry and charge/discharge cycling. The $LiFePO_4$-carbon-$TiO_2$ cathode in PVDF-PC-EC-$LiCIO_4$ electrolyte showed high capacity at high current density.