분산특성이 향상된 고효율 염료감응형 태양전지

김은미,박경희,구할본,박복기,Jin, En-Mei,Park, Kyung-Hee,Gu, Hal-Bon,Park, Bok-Kee 한국전기전자재료학회 2009 전기전자재료학회논문지 Vol.22 No.6

$TiO_2$ nano-particle paste was prepared by ethyl cellulose, $\alpha$-terpineol and bis(2-ethylhexyl) phthalate (dioxcyl phthalate) for dye-sensitized solar cells (DSSCs). Dispersion and absorbance of $TiO_2$ photoanode films was controlled by adding different amount of ethyl cellulose and $\alpha$-terpineol. The morphology of prepared $TiO_2$ films was studied by field emission scanning electron microscopy (FE-SEM) and the optical properties of $TiO_2$ films were measured by UV/vis spectra. Photovoltaic-current density was observed to determine the electrochemical response of DSSCs. Energy conversion efficiency was obtained about 7.1% at ethyl cellulose and $\alpha$-terpineol at optimal mixed ratio (as ethyl cellulose: 0.1 g; $\alpha$-terpineol: 1.5 ml) under illumination with AM 1.5($100\;Wcm^{-2}$) simulated sunlight.

MnO₂-HCS 복합체를 이용한 슈퍼커패시터의 전기화학적 특성

김은미,정상문,Jin, En Mei,Jeong, Sang Mun 한국청정기술학회 2018 청정기술 Vol.24 No.3

Hollow carbon spheres (HCS) and carbon spheres (CS) were prepared by a hydrothermal reaction and they were introduced as a substrate for the deposition of $MnO_2$ nanoparticles. The $MnO_2$ nanoparticles were deposited on the carbon surface by a chemical redox deposition method. After deposition, the $MnO_2$ nanoparticles were uniformally distributed on the carbon surface in a slit-shape, and sparse $MnO_2$ slits appeared on the HCS surface. The $MnO_2-HCS$ showed an initial specific capacitance of $164.1F\;g^{-1}$ at scan rate of $20mv\;s^{-1}$, and after 1,000 cycles, the specific capacitance was maintained to $141.3F\;g^{-1}$. The capacity retention of $MnO_2-HCS$ and $MnO_2-CS$ were calculated to 86% and 78% in the cycle performance test up to 1,000 cycles, respectively. $MnO_2-HCS$ showed a good cycle stability due to the mesoporous hollow structure which can cause a faster diffusion of the electrolyte and can easily adsorb and desorb $Na^+$ ions on the surface of the electrode.

MnO₂-HCS 복합체를 이용한 슈퍼커패시터의 전기화학적 특성

김은미(En Mei Jin),정상문(Sang Mun Jeong) 한국청정기술학회 2018 청정기술 Vol.24 No.3

상용 고용량 리튬이온이차전지용 NCA 양극활물질의 전기화학적 특성

김은미 ( En Mei Jin ),이가을 ( Ga-eul Lee ),나병기 ( Byuong-ki Na ),정상문 ( Sang Mun Jeong ) 한국화학공학회 2017 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.55 No.2

In order to investigate the electrochemical properties and the particle size effect of LiNi_1-x-yCo_xAl_yO₂ (x=0.15, y=0.045 or 0.05, NCA) for lithium ion batteries (LIBs), two commercial NCA cathode materials (NCA#1, NCA#2) were used as cathode materials for LIB. The average particle size of the NCA#1 which consisted of uniform spherical particles was found to be approximately 5 μm. NCA#2 consisted of particles with bimodal size distribution of approximately 5 μm and 11 μm. From the results of charge-discharge performance test, a high initial discharge capacity of 197.0 mAh/g was obtained with NCA#2, which is a higher value than that with NCA#1. The cycle retentions of NCA#1 and NCA#2 up to 30 cycles were 92% and 94%, respectively.

염료감응 태양전지의 염료 흡착 특성 향상에 관한 연구

김은미 ( En Mei Jin ),구할본 ( Hal Bon Gu ) 조선대학교 공학기술연구원 2011 공학기술논문지 Vol.4 No.2

The acid treatment have been used for nanocrystalline TiO2 particles. It ha been observed that nitric acid treatment can enhance transparency of thin films a well as higher level of dispersion of nanoparticles. HNO3 treated surfaces has showed higher surface area and increase in hydroxy functional groups at TiO2 photoelectrode film surfaces was observed. This process has allowed to increase the conversion efficiency of solar cell which is possibly due to higher amount of dye adsorption. These process have significantly enhanced the efficiency of DSCs for developing high sensitivity. The efficiency increased upto 11 8% and this is observed at non nitric acid treatment of TiO2 photoelectrode.

수열합성한 TiO2을 이용한 염료감응형 태양전지의 전기화학적 특성

김은미 ( En Mei Jin ),왕만림 ( Wan Lin Wang ),구할본 ( Hal Bon Gu ) 조선대학교 공학기술연구원 2013 공학기술논문지 Vol.6 No.1

In this study, the TiO2 was prepared by hydrothermal reactions; and 0.5 M, 1.0 M and 2.0 M TTIP were added. The different contents of TTIP added TiO2 are studied by X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), and photocurrent density-voltage test. The photovoltaic properties under illumination with AM 1.5 simulated under sunlight. In the results, the XRD patterns index to single-phase material having an anatage structure and the particle size of 1.0 M TTIP added TiO2 is 7.61 nm. Using the 1.0 M TTIP added TiO2 demonstrates a higher solar conversion efficiency than the other samples. We got 114% and 131% enhanced power conversion efficiency when the optimal content of TTIP.

TiO2 광전극의 광산란 특성을 이용한 염료감응형 태양전지

김은미 ( En Mei Jin ),박경희 ( Kyung Hee Park ),구할본 ( Hal Bon Gu ) 조선대학교 공학기술연구원 2010 공학기술논문지 Vol.3 No.2

In this study, we increase the solar conversion efficiency of DSSC (dye-sensitized solar cell) using nanocrystalline TiO2 semiconductor. We preparation of TiO2 photoelectrode, assembly the DSSC and put a focus in analyses electrochemical properties of DSSC by using quartz glass powder in TiO2 photoelectrode to increase light scattering effect and improved conversion efficiency. Morphology of the photoelectrode was investigate using field emission scanning electron microscopy (FE-SEM) and photovoltaic properties was examined under illumination with AM 1.5 simulated sunlight. The results showed 146% power conversion efficiency when the optimal content of quartz glass powder was 5 wt.% than another content.

리튬 폴리머 전지용 정극활물질 LiFePO4 및 LiM(x)Fe(1-x)PO4의 전기화학적 특성

김은미 ( En Mei Jin ),박경희 ( Kyung Hee Park ),구할본 ( Hal Bon Gu ) 조선대학교 공학기술연구원 2009 공학기술논문지 Vol.2 No.2

Phospho-olivine LiFePO4 and LiTi0.1Fe0.9PO4 calhode materials were prepared by the solid-state reaction at the different temperature (550, 600 and 650℃). To improve conductivity carried out Ti2+ doped LiFeP04 and we studied the effect of electrochemical performance. At the different heating temperature resulted in the didn``t appearance of impurity phase which was shown by high resolution X-ray diffraction and perepared by 600℃ temperature``s discharge performance results exhibited an excellent high capacity of 140 mAh/g at the first cycle, and 139 mAh/g after 50 cycles. The Ti2+ doped LiFeP04 started 3.36 V of flat voltage on discharge curve and showed a gentle decline in the curve compared to undoped LiFeP04 without great changes of capacity. And so, we could achieve to improve electrochemical performance as reversible, cycle life. Similarly, LiFePO4 doping with Ti2+ showed the effect of dopant which is the improved discharge capacity as 140 mAh/g and good cycling performance.

리튬 이온 이차전지용 LiCr(x)Mn(1-x)O2 정극활물질의 전기 화학적 특성

김은미 ( En Mei Jin ),전연수 ( Yeon Su Jeon ),백형렬 ( Hyoung Ryoul Beak ),구할본 ( Hal Bon Gu ),손명모 ( Myung Mo Son ) 한국전기전자재료학회 2005 한국전기전자재료학회 하계학술대회 논문집 Vol.2005 No.0

o-LiMnO2 is known to have poor cycle performance causing the irreversible phase transformation on cycling. In this paper, the effect of chemical substitution on improving cycle performance of o-LiMnO2 was studied at the compositions of LiCr(x)Mn(1-x)O2 (x=0, 0.1, 0.2, 0.4). XRD is showed that structure of LiCr(x)Mn(1-x)O2 transformed from orthorhombic to spinel according to the increase of substitute degree. For lithium ion battery applications, LiCr(x)Mn(1-x)O2/Li cell were characterized electrochemically by charge/discharge cycling.

수열법을 이용한 LiFePO4의 전기화학적 특성

김은미 ( En Mei Jin ),전대규 ( Dea Gue Jun ),한정희 ( Zhen Ji Han ),백형렬 ( Hyoung Ryoul Beak ),구할본 ( Hal Bon Gu ),박복기 ( Bok Kee Park ),손명모 ( Myung Mo Son ) 한국전기전자재료학회 2006 한국전기전자재료학회 하계학술대회 논문집 Vol.2006 No.1

Olivine LiFePO4 cathode materials were synthesized by hydrothermal reaction, and coated by carbon black. The powders were characterized by the X-ray diffraction. LiFePO4/Li cells were characterized electrochemically by charge/discharge experiments and ac impedance spectroscopy. The result showed the discharge capacity of LiFePO4/Li cell was 133 mAh/g at the first cycle, and 128 mAh/g at the 30th cycle, respectively.