• Proceedings of the Membrane Society of Korea Conference
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• 1993.10a
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• pp.63-64
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• 1993

레독스-흐름 2차전지는 발전소의 잉여전력, 태양전지 및 전기자동차 등 응용 분야가 넓은 유망한 에너지 저장 방법의 하나이다[1,2]. Fe-Cr계 2차전지와 비교하여 수소 가스의 발생이 없고 양쪽 액의 확산에의한 혼합으로 전지의 용량이 떨어지지 않고 rebalance의 필요가 없는 등 많은 장점을 가지고 있으며 조작이 간단하며 기전력 (1,4 V)과 에너지 밀도가 높기 때문에 compact화가 가능하다[1].

• Proceedings of the KIPE Conference
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• 2016.11a
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• pp.178-179
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• 2016

본 논문에서는 바나듐 레독스 플로우 배터리의 동작원리를 설명하고, C-rate에 따른 특성 분석을 하였다. 전해질 양이 18mL, 22mL일 때 0.1C, 0.3C, 0.5C, 0.7C, 0.9C, 1.0C로 전류의 크기에 변화를 주어 용량을 측정한 후 비교 분석하였다. 더불어 HPPC(Hybrid pulse power characterization) 실험에서 1.0C 일 때 잔존 용량(State-of-charge, SOC)의 변화에 따른 저항을 추출하였고 분석하였다. 그 결과 바나듐 레독스 플로우 배터리의 효율 분석을 위한 파라미터 값을 확인하였다.

• Membrane Journal
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• v.27 no.5
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• pp.415-424
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• 2017

Commonly cation exchange membranes have been used for vanadium redox flow batteries. However, a severe vanadium ion cross-over causes low energy efficiency. Thus in this study, we prepared 3 different anion exchange membranes to investigate the effect on the membrane properties such as vanadium ion cross-over and long term stability. The base membranes were prepared by an electrolyte pore filling technique using vinyl benzyl chloride (VBC), divinylbenzene (DVB) within a porous polyethylene (PE) substrate. Then 3 different functional amines were introduced into the base membranes, respectively. These resulting membranes were evaluated by physico-chemical properties such as ion exchange capacity, dimensional stability, vanadium ion cross-over and membrane area resistance. Conclusively, TEA-functionalized membrane showed longest term stability than other membranes although all the membranes are similar to coulombic efficiency.

• Journal of the Korean Electrochemical Society
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• v.24 no.4
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• pp.113-119
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• 2021

In this study, impurity free V^3.5+ electrolytes were prepared using formic acid as a reducing agent and PtD/C as a catalyst and it was applied to VRFB. The well-oriented 3D dendrite structure of the PtD/C catalyst showed high catalytic activity in formic acid oxidation reaction and vanadium reduction reaction. As a result, the conversion ratio of electrolyte using the PtD/C was 2.73 mol g^-1 h^-1, which was higher than that of 1.67 mol g^-1 h^-1 of Pt/C prepared by the polyol method. In addition, in the VRFB charging and discharging experiment, the V^3.5+ electrolyte produced by the catalytic reaction showed the same performance as the standard V^3.5+ electrolyte prepared by the electrolytic method, thus proving that it can be used as an electrolyte for VRFB.

• Journal of the Korean Electrochemical Society
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• v.19 no.1
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• pp.14-20
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• 2016

Vanadium redox flow battery (VRFB) is an energy conversion device in which charging and discharging are alternatively carried out by oxidation and reduction reactions of vanadium ions with different oxidation states. VRFB consists of electrolyte, electrode, ion-exchange membrane, etc. The role of ion-exchange membranes in VRFB separates anolyte and catholyte and provides a high conductivity to hydrogen ions. Recently much attention has been devoted to develop ideal ion-exchange membranes for VRFB. A number of developed ion-exchange membranes should be evaluated to find out ideal ion-exchange membranes for VRFB. Long-term durability test is a crucial characterization of ion-exchange membranes for commercialization, but is very time-consuming. In this study, the life time prediction protocol of ion-exchange membranes in VRFB cell tests was developed through short-term single cell performance evaluation (real total operation time, 87.5 hrs) at three different current densities. We confirmed a decrease in test time up to 96.2% of real durability tests (expected total operation time, 2,296 hrs) and 5~6% of relative error discrepancy between the predicted and the real life time in a unit cell.

• KEPCO Journal on Electric Power and Energy
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• v.7 no.2
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• pp.309-316
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• 2021

For the detection of the state of charge in VRFB-ESS, the analyses of UV-Visible spectrometry and the measurements of potential between the anolyte and catholyte were used in parallel. This paper includes the production of 4-valant ion from VOSO4 powder, 3- and 5-valant ions from electrochemical charge of 4-valant ion and 2-valant ion from 3-valant ion. It also includes the analyses of these valance ions and unknown electrolyte at any time using UV-Visible spectrometry. Through the analyses of the valance ions in samples, the SOCs of the samples at any charge-discharge times were verified.

• Journal of Electrochemical Science and Technology
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• v.8 no.2
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• pp.155-161
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• 2017

Carbon felts were prepared under various thermal conditions to improve the electrochemical properties of vanadium redox flow batteries. The number of C-O and/or C-OH functional groups on the surface of the electrodes treated under airless conditions was much larger than that of the untreated and partially oxygen-treated electrodes. The carbon felt treated under airless conditions had the lowest surface area. The overall kinetic properties of the redox reaction were greatly improved for the carbon felt treated under airless conditions; i.e., the reversibility of the anodic and cathodic reactions associated with the $VO_2{^+}/VO^{2+}$ couple became more reversible. Single-cell tests indicated that the carbon felt exhibited an excellent discharge capacity of $3.1Ah{\cdot}g^{-1}$ at $40mA{\cdot}cm^{-2}$, and the corresponding Coulombic, voltage, and energy efficiencies were 89.5%, 91.8%, and 82.2%, respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.6
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• pp.80-85
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• 2019

Vanadium dioxide is a well-known metal-insulator phase transition material. Lots of researches of vanadium redox flow batteries have been researched as large scale energy storage system. In this study, vanadium oxide($VO_x$) thin films were applied to cathode for lithium ion battery. The $VO_x$ thin films were deposited on Si substrate($SiO_2$ layer of 300 nm thickness was formed on Si wafer via thermal oxidation process), quartz substrate by RF magnetron sputter system for 60 minutes at $500^{\circ}C$ with different RF powers. The surface morphology of as-deposited $VO_x$ thin films was characterized by field-emission scanning electron microscopy. The crystallographic property was confirmed by Raman spectroscopy. The optical properties were characterized by UV-visible spectrophotometer. The coin cell lithium-ion battery of CR2032 was fabricated with cathode material of $VO_x$ thin films on Cu foil. Electrochemical property of the coin cell was investigated by electrochemical analyzer. As the results, as increased of RF power, grain size of as-deposited $VO_x$ thin films was increased. As-deposited thin films exhibit $VO_2$ phase with RF power of 200 W above. The transmittance of as-deposited $VO_x$ films exhibits different values for different crystalline phase. The cyclic performance of $VO_x$ films exhibits higher values for large surface area and mixed crystalline phase.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.10
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• pp.598-602
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• 2018

This study examined the characteristics of the waste catalyst used in the petroleum refinery operations. The total pore volume, specific surface area, and average pore size of the spent catalyst used in the petroleum refinery operations were 3.96cc/g, 13.81m2/g, and 1.15A, respectively. The weight loss observed in the range from $25^{\circ}C-700^{\circ}C$ for the spent catalysts using TG and DTA was approximately 23 wt. %. EDS analysis of the waste catalyst sample showed that the five major components were vanadium, nickel, manganese, iron, and copper. The extraction system is attractive for liquid-liquid extraction. In this study, Cynex 272 was used to extract vanadium from waste catalyst. The electrochemical characteristics of the extracted vanadium solution were measured by cyclic voltammetry (CV). As a result, an oxidation / reduction peak appeared, indicating the potential of an electrolytic solution.

• Proceedings of the KIPE Conference
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• 2018.07a
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• pp.231-233
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• 2018

바나듐 산화 환원 유동 배터리는 긴 수명주기와 높은 에너지효율로 리튬 이온 배터리를 대체할 차세대 배터리로 주목받고 있다. 에너지가 저장되는 전해질을 순환시키면서 충전 과방전이 이루어진다는 이차전지 인 만큼 유지 보수 비용을 획기적으로 절감할 수 있고 사용자의 요구조건에 따라 출력과 에너지 용량을 매우 쉽게 조절할 수 있다는 장점이 있다. 하지만, 바나듐 산화 환원 유동 배터리를 다양한 어플리케이션에 적용하기 위하여 바나듐 배터리 운용에서 여러 가지 요소들을 고려하여야 한다. 본 논문에서는 충전 및 방전을 지속했을 때의 용량 감소하는 바나듐 산화 환원 유동 배터리의 특성을 고려하여 가장 까다로운 문제 중 하나인 휴지 기간에서의 자가 방전에 대해 온도와 SOC에 따라 특성 분석을 실시하였다.