검색결과

검색조건
좁혀보기
검색필터
결과 내 재검색

간행물

    분야

      발행연도

      -

        검색결과 16

        1.
        2004.05 구독 인증기관 무료, 개인회원 유료
        Electrodes were fabricated based on activated carbon powder BP-20, conducting agent such as Super P, vapor grown carbon fiber (VGCF) and acetylene black (AB), and the mixed binders of flexible poly(vinylidenefluoridehexafluoropropylene) [P(VdF-co-HFP)] and cross linking dispersion agent of polyvinylpyrrolidone (PVP) to increase mechanical strength. According to impedance measurement of the electrode with the addition of conducting agent, we found that it was possible to charge rapidly by the fast steady-state current convergence due to low equivalent series resistance (AC-ESR, fast charge transfer rate at interface between electrode and electrolyte and low RC time constant. The self-discharge of unit cell showed that diffusion process was controlled by the ion concentration difference of initial electrolyte due to the characteristics of Electric Double Layer Capacitor (EDLC) charged by ion adsorption in the beginning, but this by current leakage through the double-layer at the electrode/electrolyte interface had a minor effect and voltages of curves were remained constant regardless of electrode material. We found that the 2.3V/230F grade EDLC would be applied to industrial safety usage such as uninterrupted power supply (UPS) because of the constant DC-ESR by IR drop regardless of discharge current.
        4,200원
        2.
        2003.11 구독 인증기관 무료, 개인회원 유료
        The optimum polymer gel electrolyte composition ratio was 23 : 66 : 11 wt% of P(VdF-co-HFP) : PVP =20 : 3), (PC: EC =44 : 22) and TEABF4. And the optimal thickness of polymer gel electrolyte was 50um . The electrochemical characteristics result of unit cell were 31.41 Fig of specific capacitance, and 3.21x10-3 S/cm of ion conductivity. Ion conductivity of polymer gel electrolytes decreased according to added PVP through impedance analysis, and it was higher in 7 wt%, but electrochemical characteristics of unit cell were better in 3 wt% PVP. And for excellent ion conductivity of polymer gel electrolytes, the use of a thin layer electrolyte(20um) was an effective method, but with unit cell application, the best thickness was 50um . Unit cell showed higher capacitance and more stable electrochemical performance when hot pressed between polymer gel electrolyte and electrode. This results from enhancement of the physical contact between the electrode and the polymer gel electrolyte and good accessibility of the liquid electrolyte to the electrode surface.
        4,000원
        3.
        2003.11 구독 인증기관 무료, 개인회원 유료
        The best Ppy weight ratio was 7 wt% and the optimal electrode composition ratio was 78 : 17 : 5 wt.% of (MSP-20 : BP-20 =1 : 1), (Super P : Ppy =10 : 7) and P(VdF-co-HFP). Implantation of Ppy as the conducting agents have led to superior electrochemical characteristics because of the low of internal resistance and faradaic capacitance. The result of unit cell with Ppy 7 wt% were as follows: 28.02 Fig of specific capacitance, 1.34 Ω of DC-ESR and 0.36 Ω of AC-ESR. Unit cell showed a good stability up to 200 charge-discharge cycles, retaining 82% of their original capacity at 200 cycles. From the analysis of impedance, the electrodes with Ppy 7 wt% showed low ESR, low charge transfer resistance and quick reaction rate. It was inferred that quick charge-discharge was possible. As compared with the specific capacitance (rectangular shape) of CV, it was also concluded that the specific capacitance originated from thecompound phenomena of the faradaic capacitance by oxidation and reduction of Ppy and the non-faradaic capacitance by adsorption-desorption of activated carbon.
        4,000원
        4.
        2003.11 구독 인증기관 무료, 개인회원 유료
        In the electrode fabrication of unit cell, it was ascertained that electrochemical characteristics were greatly increased with 90 wt.% of BP-20, 5 wt.% of Super P and 5 wt.% of mixed binder [P(VdF-co-HFP) : PVP =7 : 3] The self-discharge of unit cell showed that diffusion process was controlled by the ion concentration difference of initial electrolyte due to the characteristics of Electric Double Layer Capacitor (EDLC) charged by ion adsorption in the beginning, but this by current leakage through the double-layer at the electrode/electrolyte interface had a minor effect and voltages of curves were remained constant regardless of electrode material. The electrochemical characteristics of 2.3 V/3,000 F grade EDLC were as follows: 0.35 m of DC-ESR (100 A discharge), 0.14 mof AC-ESR (AC amplitude 100 mV), 2.80 Wh/kg (3.73 Wh/L) of energy density and 4.64 kW /kg (6.19 kW/L) of power density. Power output was compatible with electric vehicle applications, uninterrupted power supply and engine starter, in due consideration of Ragone relations.
        4,000원
        5.
        2002.11 구독 인증기관 무료, 개인회원 유료
        All-vanadium redox flow battery(VRFB) has been studied actively as one of the most promising electrochemical energy storage systems for a wide range of applications such as electric vehicles, photovoltaic arrays, and excess power generated by electric power plants at night time. CPCS has been shown to have the characteristics as an excellent current collector for VRFB and electrochemical properties of specific resistivity 0.31 Ω cm, which were composed of G-1028 80 wt%, PVC 10 wt%, DBP 5 wt% and FS 5 wt%. Energy efficiencies of VRFB with the CPCE and the existing electrode assembly were 84.14 % and 77.24 % respectively, in charge/discharge experiments at constant current of 200 mA, and the CPCE was confirmed to be suitable as the electrode of VRFB.
        4,000원
        6.
        2002.11 구독 인증기관 무료, 개인회원 유료
        In the electrode fabrication of unit cell, we found that optimal the electrochemical characteristics were obtained with at 90 wt.% of activated carbon(BP-20), 5 wt.% of conducting agent(Ppy, Super P) and 5 wt.% of P(VdF-co-HFP)/PVP mixed binder. The electrochemical characteristics of unit cell with Ppy improver were as follows : 37.6 F/g of specific capacitance, 0.98 Ω of AC-ESR, 2.92 Wh/kg and 6.05 Wh/L of energy density, and 754 W/kg and 1,562 W/L of power density. It was confirmed that internal resistance were reduced due to the increase of electrical conductivity and filling density by the introduction of conductivity agent, and content of conducting agent was suitable in the range of 4~6 wt.%. According to the impedance measurement of the electrode with conductivity agent, we found that it was possible to charge rapidly by the fast steady-state current convergence due to low equivalent series resistance(AC-ESR), fast charge transfer rate at interface between electrode and electrolyte, and low RC time constant.
        4,000원
        7.
        2001.11 구독 인증기관 무료, 개인회원 유료
        The electrodes were fabricated by compounding the commercial activated carbons and additives of conducting polymer with PVdF mono binder and PVdF-PVP mixed binders. The best performance of the electrodes fabricated with activated carbon(BP-20) and PVdF-PVP mixed binders showed in 88wt. % BP-20. 7wt. % conducting polymer and 5wt.% PVdF-PVP mixed binder. The electrode exhibited excellent electrochemical characteristics having 8.16 W.h/kg of energy density, 34.77 F/g of specific capacitance, 0.67Ω of ESR.
        3,000원
        8.
        2001.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Resource recovery and recycling of materials and products, including polyurethanes is viewed as a necessity in today's society. Most urethane polymers are made from a polyol and a diisocyanate. these and be chemicals such as water, diamines or diols that react with isocyanate groups and add to the polymer backbone. The problems of recycling polyurethane wastes has major technological, economic and ecological significance because polyurethane itself is relatively expensive and its disposal whether by burning is also costly. In general, the recycling methods for polyurethane could be classified as mechanical, chemical and feedstock. In the chemical recycling method, there are hydrolysis, glycolysis, pyrolysis and aminolysis. This study, the work was carried out glycolysis using sonication ant catalyzed reaction. Different kinds of recycled polyols were produced by current method(glycolysis), catalyzed reaction and sonication as decomposers and the chemical properties were analyzed. The reaction results in the formation of polyester urethane diols, the OH value which is determined by the quantity of diol used for the glycolysis conditions. The glycolysis rates by sonication for the various glycols, increased as fallows: PPG <PEG < DEG < EG. The recycled polyol of sonication reaction had much higher OH value, much lower decomposition temperature and time than the recycled polyol of current method in which same glycols and catalyst were used.
        4,000원
        9.
        2001.05 구독 인증기관 무료, 개인회원 유료
        High surface area and high pore volume activated carbon was prepared by KOH activation of rice hull. The electrodes were fabricated by compounding the commercial and rice hull activated carbons with PVdF and PVdF-PVP mixed binders without addition of conductivity improver. The electrodes fabricated with rice hull activated carbon and PVdF-PVP mixed binders showed the best performance because the PVP played as a pore-forming agent. The electrode exhibited excellent electrochemical characteristics having 7.9 W.h/kg of energy density, 33.5 F/g of speific capacitance, 0.7 Ω of ESR and good efficiency of self-discharge compared with that fabricated with commercial activated carbons.
        4,000원
        10.
        2000.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Electrochemical charateristics of activated carbon fiber cloth(ACFC) electrode were studied with propylene carbonate(PC), γ-butyrolactone(GBL) and N,N-dimethyl-formamide(DMF) as a solvent and tetraethylammoniumtetrafluoroborate(TEABF4), tetraethylammoniumhexafluorophosphate(TEABF6), tetrabutylammoniumtetrafluoroborate(TBABF4) and tetrabutylammonium hexafluorophosphate(TBAPF6) as an electrolytes(active material). The concentrations of electrolytes were in the range of 0.2~1.2 N, the volume ratios of PC and DMF as a mixed solvent system, were 90:10, 80:20, 70:30, 60:40, 50:50, and 40:60 vol%. Electrochemical characteristics such as electric conductivity, internal resistance, and electric capacitance of fabricated unit cells were measured after the moisture of activated material was removed with molecular sieve. Electrochemical characteristics were better in mixed solvents system than in mono solvent system. The mono solvent system of 1.0 N electrolyte of GBL/TEABF4 with activated carbon cloth electrodes showed better result but the mixed solvent system with PC and DMF/TEABF4(50:50 vol%) and the concentration of 1.0 N electrolyte showed the best characteristics. Internal resistance was 3.47 Ω and specific capacitance was 19.1 F/g respectively.y.
        4,600원
        11.
        2000.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In consideration that a high tensile strength and ion exchange capacity are maintained as the swℓing of membrane is controlled by the coagulation of PSf with the introduction of ion exchange groups and PPSS without the introduction of ion exchange groups, the block copolymer of PSf and PPSS were synthesized. The cation exchange membrane was prepared by sulfonation with CSA and casted. The synthesized block copolymer and cation exchange membrane were characterized by FT-IR and their thermal stability was confirmed by TGA. The optimum sulfonation could be accomplished at a mole ratio of BPSf to CSA 1:3. The best electrochemical properties obtained by the optimal condition were area resistance of 4.37 Ωㆍtextrmcm2, ion exchange capacity of 1.71 meq/g dry membrane, water content of 0.2941 g H2O/g dry membrane, and fixed ion concentration of 5.81 meq/g H2O. When GBL was used as an additive, area resistance was increased by 13.7 % and ion exchange capacity was increased by 14.6%. When the membrane was fabricated in a form of composite using non woven cloth as a support. the tensile strength of membrane could be improved, but the electrochemical characteristics were not influenced.
        4,000원
        13.
        1999.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        운반체(감응물질)로 제 4급 인산염을 사용하여 PVC를 지지체로 하여 과염소산이온의 농도 10-6 M까지 선형적인 이온선택성 전극을 제작하였다. 운반체의 화학적구조와 함량 가소제의 종류 및 막 두께에 따른 전극의 기울기 선형응답범위 및 한계측정농도 등 전극전위특성을 고려하여 최적의 과염소산 이온선택성 PVC막 전극을 제조한 다음 측정 가능한 pH 범위 선택계수 및 전극의 교류임피던스 특성을 비교 검토하였다 운반체로 tetraoctyl-phosphonium perchlorate(TOPP) tetraphenylphosphonium perchlorate(TPPP) 및 tetrabutylphosponium perchlorate (TBPP) 등의 제 4급 인산염의 과염소산 이온 치환체를 사용하였다 알킬기의 탄소고리 수가 증가할수록 전극특성은 TBPP, 선형응답범위 10-1×10-6 M 및 한계측정농도는 9.66×10-7 M 이었으며 시판되고 있는 Orion 전극특성보다 좋은 결과를 나타내었다 전극전위는 pH3~11범위에서 ph의 영향을 받지 않았으며 CIO4 에 대한 방해이온의 선택계수 서열은 SO24 < F < Br < I 이었다 임피던스 측정결과 TOPP의 경우 등가회로는 용액저항 이중층용량과 벌크저항의 병렬 및 Warburg 임피던스의 직렬이었다 이 경우 용액저항은 거의 나타나지 않았고 확산에 의한 Warburg 임피던스는 크게 나타났으며 Warburg 계수는 1.32×1074 Ω cdot cm2/s1/2이었다.
        4,000원
        14.
        1999.11 구독 인증기관 무료, 개인회원 유료
        A new type of capacitor named "Super Capacitor" has been developed, in which the properties of electric double layer formed at the interface of activated carbon electrode- liquid organic electrolyte is applied. This capacitor is small In size, light in weight, wide In temperature range(-25~70℃), large in charge-discharge capability and good in voltage preservation. And this super capacitor is applied as a power back-up for electricity failure in volatile memory devices etc., a power source for a short time and a power source for operating actuators. At present the development of high power back-up types of the capacitor system and improvement of their characteristics are being actively conducted in order to find wider applications.lications.
        4,000원
        15.
        1995.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구에서는 복합막의 합성을 위한 기초연구로 상용막에 대한 전기화학적 물성과 레독스-흐름전지의 충방전실험을 통해 셀저항과 막저항을 특정하였다. 셀저항율과 막저항율은 충전할 때보다 방전할 때가 더 높았으며 동일한 막에서는 충전심도가 커질수록 저항율이 커짐을 알 수 있었다. hydrocarbon type인 Selemion CMV막이 perfluoro type인 nafion 117, 551막보다 저항율이 작음을 알 수 있었으며 2N 염산수용액에서 충전심도가 0%일 때 셀 저항율과 막저항율이 각각 12.864Ωcm2 , 8.751Ωcm2 였다.
        4,000원
        16.
        1993.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        감응물질로 제4급 암모늄염을 사용하여 PVC를 지지체로 과염소산이온의 농도 10-6M까지 측정가능한 이온 선택성 전극을 제작하였다. 감응물질의 화학적 구조와 함량, 가소제의 종류 및 막 두께에 따른 선형응답 범위와 Nernst의 기울기 등 전극특성을 검토하여, 최적 막조건을 구한 다음 측정가능 pH범위와 여러 방해이온에 대한 선택계수를 비교 검토하였다. 과염소산 이온선택성 전극에서 감응물질의 화학적 구조 즉, 알킬기의 탄소고리수가 증가할수록 선형응답 범위 등 전극 특성은 Aliquat 336P, TOAP, TDAP 및 TDDAP의 순서로 좋아졌다. 가소제는 DBP가 가장 좋았고, 감응물질의 양은 최적 함량 이상에서 적을수록 좋았다. 최적 막 조성은 TDDAP 9.09, PVC 30.3 및 DBP 60.61wt%이었고, 막두께 0.45mm이었다. 이 조건에서 선형응답 범위 10-1~1.2 × 10-6M, 검출한계 5.1×10-7M 및 Nernst기울기 57mV/pClO4이었다. 막전위는 pH 4~11 범위에서 pH의 영향을 받지 않았으며, 선택계수 서열은 다음과 같았다. SCN->I->NO3->Br->ClO3->F->Cl->SO42-
        4,000원