• Journal of Electrical Engineering and Technology
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• 제10권3호
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• pp.1102-1106
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• 2015

A hybrid supercapacitor (HS) is an energy storage device used to enhance the low weight energy density (Wh/kg) of a supercapacitor. On the other hand, a sudden decrease in capacity has been pointed out as a reliability problem after many charge/discharge cycles. The reliability problem of a HS affects the early aging process. In this study, the capacity performance of a HS was observed after charge/discharge. For detailed analysis of the initial charge/discharge cycles, the charge and discharge curve was measured at a low current density. In addition, a solid electrolyte interphase (SEI) layer was confirmed after the charge/discharge. A HC composed of a lithium titanate (LTO) anode and active carbon cathode was used. The charge/discharge efficiency of the first cycle was lower than the late cycles and the charge/discharge rate was also lower. This behavior was induced by SEI layer formation, which consumed Li ions in the LTO lattice. The formation of a SEI layer after the charge/discharge cycles was confirmed using a range of analysis techniques.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 추계학술대회 논문집
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• pp.159-162
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• 1999

All solid state thin film micro-batteries consisting of lithium metal anode, an amorphous LiPON electrolyte and cathode of vanadium oxide have been fabricated and characterized, which were fabricated with cell structure of Li/LiPON/V$_2$O$\sub$5/Pt. The vanadium oxide thin films were formed by d.c. reactive sputtering on Pt current collector. After deposition of vanadium oxide films, in-situ growths of lithium phosphorus oxynitride film were conducted by r.f. sputtering of Li$_3$PO$_4$ target in mixture gas of N$_2$ and O$_2$. The pure metal lithium film was deposited by thermal evaporation on thin film LiPON electrolyte. The cell capacity was about 45${\mu}$Ah/$\textrm{cm}^2$ $\mu\textrm{m}$ after 200 cycle. No appreciable degradation of the cell capacity could be observed after 50 cycles .

• 한국분말재료학회지
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• 제29권6호
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• pp.485-491
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• 2022

Lithium lanthanum titanium oxide (LLTO) is a promising ceramic electrolyte because of its high ionic conductivity at room temperature, low electrical conductivity, and outstanding physical properties. Several routes for the synthesis of bulk LLTO are known, in particular, solid-state synthesis and sol-gel method. However, the extremely low ionic conductivity of LLTO at grain boundaries is one of the major problems for practical applications. To diminish the grain boundary effect, the structure of LLTO is tuned to nanoscale morphology with structures of different dimensionalities (0D spheres, and 1D tubes and wires); this strategy has great potential to enhance the ion conduction by intensifying Li diffusion and minimizing the grain boundary resistance. Therefore, in this work, 0D spherical LLTO is synthesized using ultrasonic spray pyrolysis (USP). The USP method primarily yields spherical particles from the droplets generated by ultrasonic waves passed through several heating zones. LLTO is synthesized using USP, and the effects of each precursor and their mechanisms as well as synthesis parameters are analyzed and discussed to optimize the synthesis. The phase structure of the obtained materials is analyzed using X-ray diffraction, and their morphology and particle size are analyzed using field-emission scanning electron microscopy.

• 한국전기화학회:학술대회논문집
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• 한국전기화학회 2003년도 추계총회 및 학술발표회
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• pp.71-71
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• 2003

• 한국세라믹학회지
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• 제42권6호
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• pp.425-431
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• 2005

Line Shaped Solid Oxide Fuel Cell (SOFC) with multilayered structure has been fabricated via direct-writing process. The cell is electrolyte of Ni-YSZ cermet anode, YSZ electrolyte and LSM cathode. They were processed into pastes for the direct writing process. Syringe filled with each electrode and electrolyte paste was loaded into the computer-controlled robe-dispensing machine and the paste was dispensed through cylindrical nozzle of 0.21 mm in diameter under the air pressure of 0.1 tow onto a moving plate with 1.22 mm/s. First of all, the anode paste was dispensed on the PSZ porous substrate, and then the electrolyte paste was dispensed. The anode/electrolyte and the PSZ substrate were co-fired at $1350^{\circ}C$ in air atmosphere for 3 h. The cathode layer was similarly dispensed and sintered at $1200^{\circ}C$ for 1 h. All the electrode/electrolyte lines were visually aligned during the direct writing process. The effective reaction area of fabricated SOFC was $0.03 cm^2$, and the thickness of anode, electrolyte and cathode was 20 $\mu$m, 15 $\mu$m, and 10 $\mu$m, respectively. The single line-shaped SOFC fabricated by direct-writing process exhibited OCV of 0.95 V and maximum power density of $0.35W/cm^2$ at $810^{\circ}C$.

• Macromolecular Research
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• 제9권5호
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• pp.292-295
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• 2001

A cross-linked solid polymer electrolyte was prepared by copolymerizing photochemically acrylonitrile (AN), oligo(ethylene glycol ethyl ether) methacrylate, oligo(ethylene glycol) dimethacrylate in the presence of lithium perchlorate as a lithium salt, ethylene carbonate-propylene carbonate as a mixed plasticizer, and poly(ethylene oxide) as a polymer matrix. The maximum ionic conductivity of the polymer electrolyte was 2.35$\times$10$\^$-3/ S/cm. The interface resistance of the polymer electrolyte was very low compared to that of the polymer electrolyte without AN. The former electrolyte was stable up to 4.3 V and the Ah efficiency was nearly 100% during the charge-discharge cycle.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1998년도 춘계학술대회 논문집
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• pp.159-162
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• 1998

The new type polymer electrolyte composed of polyacrylonitrile(PAN) baed polymer electrolyte contain LiClO$_4$-EC/PC and LiPF$\sub$6/-EC/PC were developed for the weightless and long or life time of lithium polymer battery system with using polyaniline electrode. The gel type electrolytes were prepared by PAN at different lithium salts in the glove box. We prepared for polymer electrolyte with knife casting method. The minimum thickness of PAN gel electrolyte for the slim type is about <400∼500$\mu\textrm{m}$. These gel electrolytes showed good compatibility with lithium electrode. The test cell of Li/polymer electrolyte/Lithium cobalt oxide solid state cell which was prepared by different lithium salt was researched by electrochemical technique. Resistance of polymer electrolyte which consist of LiClO$_4$ is more less than that of LiPF$\sub$6/ and cycle life is more longer than that of LiPF$\sub$6/.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 추계학술대회 논문집
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• pp.374-377
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• 1999

The purpose of this study is to research and develop solid polymer electrolyte(SPE) for Li polymer battery. This paper describes temperature dependence of conductivity, impedance spectroscopy, electrochemical properties of PVDF/PAN electrolytes as a function of a mixed ratio. PVDF/PAN based polymer electrolyte films were prepared by thermal gellification method of preweighed PVDF/PAN, plasticizer and Li salt. The conductivity of PVDF/PAN electrolytes was 10-3S/cm. 20PVDF5PANLiCIO$_4$PC$\sub$10//EC$\sub$10/ electrolyte shows the better conductivity of the others. 20P7DF5PANLiCI$_4$PC$\sub$10//EC$\sub$10/ electrolyte remains stable up to 5V vs. Li/Li$\^$+/. Steady state current method and ac impedance used for the determination of transference numbers in PVDF/PAN electrolyte film. The transference number of 20PVDF5ANLICIO$_4$/PC $\sub$10//EC$\sub$10/ electrolyte is 0.48

• 한국세라믹학회지
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• 제47권2호
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• pp.195-198
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• 2010

It has been considered to apply GDC ($Gd_{0.1}Ce_{0.9}O_{1-X}$) for low-temperature SOFC electrolytes because it has higher ionic conductivity than YSZ at low temperature. However, open circuit voltage with using GDC ($Gd_{0.1}Ce_{0.9}O_{1-X}$) electrolyte in SOFCs, becomes lower than using YSZ (8 mol% Yttria stabilized Zirconia) electrolyte because GDC has electronic conductivity. In this work, the effect of changing GDC electrolyte thickness on the open circuit voltage has been investigated. Ni-GDC anode-supported unit cells were fabricated as follows. Mixed NiO-GDC powders were pressed and pre-sintered at $1200^{\circ}C$. And then, GDC electrolyte material was dip-coated on the anode and sintered at $1400^{\circ}C$. Finally the LSCF-GDC cathode material was screen-printed on the electrolyte and sintered at $1000^{\circ}C$. Electrolyte thickness was controlled by the number of dip-coating times. Open circuit voltage was measured depending on electrolyte thickness at $650^{\circ}C$ and found that the thicker GDC electrolyte was, the better OCV was.

• Transactions on Electrical and Electronic Materials
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• 제15권4호
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• pp.189-192
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• 2014

Yttria-stablized zirconia (YSZ) is the most commonly used electrolyte material, but the reduction in working temperature leads to insufficient ionic conductivity. Ceria based electrolytes (GDC) are more attractive in terms of conductivity at low temperature, but these materials are well known to be reducible at very low oxygen partial pressure. The reduction of electrolyte resistivity is necessary to overcome cell performance losses. So, thin YSZ/GDC bilayer technology seems suitable for decreasing the electrolyte resistance at lower operating temperatures. Bilayer electrolytes composed of a galdolinium-doped $CeO_2$ ($Ce_{0.9}Gd_{0.1}O_{1.95}$, GDC) layer and yttria-stabilized $ZrO_2$ (YSZ) layer with various thicknesses were deposited by RF sputtering and E-beam evaporation. The bilayer electrolytes were deposited between porous Ni-GDC anode and LSM cathode for anode-supported single cells. Thin film structure and surface morphology were investigated by X-ray diffraction (XRD), using $CuK{\alpha}$-radiation in the range of 2ce morphol$^{\circ}C$. The XRD patterns exhibit a well-formed cubic fluorite structure, and sharp lines of XRD peaks can be observed, which indicate a single solid solution. The morphology and size of the prepared particles were investigated by field-emission scanning electron microscopy (FE-SEM). The performance of the cells was evaluated over $500{\sim}800^{\circ}C$, using humidified hydrogen as fuel, and air as oxidant.