• Title, Summary, Keyword: 카본 펠트

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Development of Carbon Felt Electrode Using Urea for Vanadium Redox Flow Batteries (Urea를 이용한 바나듐 레독스 흐름 전지용 카본 펠트 전극 개발)

  • Kim, So Yeon;Kim, Hansung
    • Korean Chemical Engineering Research
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    • v.57 no.3
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    • pp.408-412
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    • 2019
  • In this study, nitrogen doped carbon felt was prepared by pyrolysis of urea at high temperature and applied as an electrode for vanadium redox flow cell. Urea is easier to handle than ammonia and forms $NH_2$ radicals at higher temperatures, creating a nitrogen functional group on the carbon surface and acting as an active site in the vanadium redox reaction. Therefore, the discharge capacity of activated carbon felt electrodes using urea was 14.9 Ah/L at a current density of $150mA/cm^2$, which is 23% and 187% higher than OGF and GF, respectively. These results show the possibility that activated carbon felt electrode using urea can be used as electrode material for redox flow battery.

Development of Boron Doped Carbon Using CO2 Reduction with NaBH4 for Vanadium Redox Flow Battery (수소화 붕소 나트륨 (NaBH4) 과 이산화탄소의 환원을 이용한 바나듐 레독스 흐름전지용 탄소 촉매 개발)

  • Han, Manho;Kim, Hansung
    • Journal of the Korean Electrochemical Society
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    • v.21 no.1
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    • pp.1-5
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    • 2018
  • In this study, boron - doped carbon was prepared by reducing carbon dioxide ($CO_2$) at high temperature by using sodium borohydride ($NaBH_4$). The boron - doped carbon was coated on carbon felt and applied as an electrode for a vanadium redox battery cell. As a result of electrochemical performance evaluation, reversibility of carbon felt coated with boron doped carbon compared to pure carbon felt was improved by about 20% and charge transfer resistance was reduced by 60%. In the charge / discharge results, energy density and energy efficiency were improved by 21% and 12.4%, respectively. These results show that carbon produced by reduction of $CO_2$ can be used as electrode material for redox flow battery.

Electrochemical Enhancement of Carbon Felt Electrode for Vanadium Redox Flow Battery with Grephene Oxide (산화그레핀을 이용한 바나듐레독스흐름전지용 카본펠트전극의 표면개질을 통한 전기화학적 활성개선)

  • LEE, KEON JOO;KIM, SUNHOE
    • Transactions of the Korean hydrogen and new energy society
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    • v.28 no.2
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    • pp.206-211
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    • 2017
  • Carbon felt electrode for the vanadium redox-flow battery (VRFB) has been studied to see the effect of grephene oxide (GO) treatment on the surface of the carbon felt electrode. In this paper, surface of carbon felt electrodes were treated with various concentrations of grephene oxide. Electrochemical analysis, cyclic voltammetry (CV), was performed to investigate redox characteristics as electrode for VRFB. Also the effect of GO on the introduction of functional group on the surface of carbon felt electrodes were investigated using X-ray photoelectron spectroscopy (XPS), which discovered increase in the overall functional group content on the surface of carbon felts.

Surface Treatment with Alkali Solution of Carbon Felt for Vanadium Redox Flow Battery (바나듐레독스흐름전지용 카본펠트전극의 알칼리용액을 이용한 표면개질)

  • KIM, SUNHOE;LEE, KEON JOO
    • Transactions of the Korean hydrogen and new energy society
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    • v.27 no.4
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    • pp.372-377
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    • 2016
  • The carbon felt used as the electrode of vanadium redox flow battery (VRFB) requires imprived electrochemical activity for better battery performance and efficiencies. Many efforts have been tried to improve electrochemical activity of the carbon felt as electrodes. In this study the alkali solution, KOH, is applied on surface treatment of the carbon felt electrode. The carbon felts were treated with KOH under room temperature and $80^{\circ}C$. The isopropyl alcohol was applied to improve wettability of the carbon felt during KOH treatment. The KOH treated carbon felt was analyzed by using the X-ray photoelectron spectroscopy (XPS). The XPS analysis of carbon felt electrode revealed on increase in the overall surface oxygen content of the carbon felts after KOH treatment. Also, cyclic voltametry tests showed electrochemical characteristics enhancement of the carbon felt.

Effect of the redox flow battery and electrode characteristics according to the heat treatment temperature of a carbon felt (탄소펠트의 열처리 온도에 따른 레독스흐름전지와 전극 특성에 미치는 영향)

  • Yoo, Hyosung;You, Hyunjin;Yu, Kihyun;Kang, Junyoung;Park, Hongsik;Choi, Woonghwi;Yoo, Dong Jin
    • Journal of Energy Engineering
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    • v.24 no.3
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    • pp.89-95
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    • 2015
  • Carbon felts manufactured by (Co)CNF were subjected to heat treatment under different temperatures to use for the electrode of a redox-flow battery. BET and weight loss were tested to investigate the physical properties of the carbon felt according to the heat treatment conditions. SEM and XPS were also analyzed to characterize their surface area. In addition, electrical resistance, CV (cyclic voltammetry) and RFB charge on the electrode properties were examined in accordance with the heat treatment conditions with the discharge performance. The changes of physical properties on the carbon felt surface was confirmed via SEM and BET analysis, The most addition of oxygen functional groups on the carbon felt surface was obtained when one hour heat treatment at $550^{\circ}C$ and it was confirmed by XPS analysis. After resulting the CV tests, the active area of the electrode was the largest at $550^{\circ}C$ heat treatment. The heat treatment experiment of vanadium redox flow battery using the carbon felts were tested at $400^{\circ}C$, $500^{\circ}C$ and $550^{\circ}C$. As a result, the charge-discharge energy efficiency of the heat treatment electrode was 72.9% and 79.8%, at $400^{\circ}C$ and $500^{\circ}C$, respectively. The efficiency of the heat treatment electrode at $550^{\circ}C$ was the best as 79.8% at $550^{\circ}C$.

Effect of Electrolyte Flow Rates on the Performance of Vanadium Redox Flow Battery (바나듐레독스흐름전지 전해질 유량에 따른 성능변화)

  • LEE, KEON JOO;KIM, SUNHOE
    • Transactions of the Korean hydrogen and new energy society
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    • v.26 no.4
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    • pp.324-330
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    • 2015
  • The electrolyte flow rates of vanadium redox flow battery play very important role in terms of ion transfer to electrolyte, kinetics and pump efficiency in system. In this paper a vanadium redox flow battery single cell was tested to suggest the optimization criteria of electrolyte flow rates on the efficiencies. The compared electrolyte circulation flow rates in this experimental work were 15, 30 and 45 mL/min. The charge/discharge characteristics of the flow rate of 30 mL/min was the best out of all flow rates in terms of charging and discharging time. The current efficiencies, voltage efficiencies and energy efficiencies at the flow rate of 30 mL/min were the best. The IR losses obtained at thd current density of $40mA/cm^2$, at the flow rates of 15, 30 and 45 mL/min were 0.085 V, 0.042 V and 0.115 V, respectively. The charge efficiencies at the current density of $40mA/cm^2$ were 96.42%, 96.45% and 96.29% for the electrolyte flow rates of 15, 30 and 45 mL/min, respectively. The voltge efficiencies at the current density of $40mA/cm^2$ were 77.34%, 80.62% and 76.10% for the electrolyte flow rates of 15, 30 and 45 mL/min, respectively. Finally, the energy efficiencies at the current density of $40mA/cm^2$ were 74.57%, 77.76% and 73.27% for the electrolyte flow rates of 15, 30 and 45 mL/min, respectively. The optimum flow rates of electrolytes were 20 mL/min in most of operating variables of vanadium redox flow battery.

Electrochemical Oxidation of Carbon Felt for Redox Flow Battery (Redox flow battery용 carbon felt 전극의 전기화학적 산화)

  • Jung, Young-Guan;Hwang, Gab-Jin;Kim, Jae-Chul;Ryu, Cheol-Hwi
    • Transactions of the Korean hydrogen and new energy society
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    • v.22 no.5
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    • pp.721-727
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    • 2011
  • All vanadium redox-flow battery (VRFB) has been studied actively as one of the most promising electrochemical energy storage systems for a wide rage of applications such as electric vehicles, photovoltaic arrays, and excess power generated by electric power plants at night time. In this study, carbon felt electrodes were treated by electrochemical oxidation with KOH, and the cyclic voltammetry were studied in order to investigate redox reactivity of vanadium ion species with carbon felt electrodes. Besides the effect of electrochemical oxidation on the surface chemistry of carbon felt electrodes were investigated using the X-ray photoelectron spectroscopy (XPS). After electrochemical oxidation, XPS analysis of PAN based GF20-3 carbon felt electrode revealed on increase in the overall surface oxygen content of the carbon felts after electrochemical oxidation. Redox reaction characteristics using cyclic voltammetry (CV) were ascertained that the electrochemical treated electrode were more reversible than the untreated electrode.