• Korean Chemical Engineering Research
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• 제57권3호
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• pp.408-412
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• 2019

본 연구에서는 urea를 이용해 질소 도핑된 카본 펠트 전극을 제조하고 이를 바나듐 레독스 흐름 전지용 전극으로 적용하였다. Urea는 암모니아 보다 취급이 용이할 뿐 아니라 고온 열분해를 통해 $NH_2$ 라디칼이 발생하여 탄소 표면에 질소 작용기를 만들고 이는 바나듐 이온의 산화/환원 반응을 향상시키는 활성점(active site)로 작용한다. Urea로 활성화된 카본 펠트 전극은 $150mA/cm^2$의 전류 밀도에서 14.9 Ah/L의 방전 용량을 보였으며 이는 산소작용기로 활성화된 카본 펠트(OGF) 및 비활성화 카본 펠트(GF)보다 각각 23% 및 187% 더 높았다. 이러한 결과는 urea로 활성화된 카본 펠트 전극이 레독스 흐름 전지용 전극 소재로 사용될 수 있는 가능성을 보여준다.

• 전기화학회지
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• 제21권1호
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• pp.1-5
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• 2018

본 연구에서는 수소화 붕소 나트륨 ($NaBH_4$)를 이용하여 고온에서 이산화탄소 ($CO_2$)를 환원시켜 붕소가 도핑된 카본을 제조하였고, 이를 카본 펠트에 코팅하여 바나듐 레독스 흐름전지용 전극으로 적용하였다. 전기화학적 성능 평가 결과, 순수 카본펠트 대비 붕소 도핑된 카본으로 코팅된 카본펠트의 가역성이 약 20% 향상되었고 전하 전달 저항이 60% 감소하였다. 충/방전 결과에서는, 에너지 밀도와 에너지 효율이 각각 21%와 12.4% 향상되었다. 이러한 결과는 $CO_2$를 환원시켜 제조한 탄소가 레독스 흐름전지용 전극소재로 사용될 수 있는 가능성을 보여준다.

• 한국수소및신에너지학회논문집
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• 제28권2호
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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.

• 한국수소및신에너지학회논문집
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• 제27권4호
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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.

• 한국수소및신에너지학회논문집
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• 제32권4호
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• pp.256-262
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• 2021

A carbon felt electrode was prepared using ozone and ammonia sequential treatment and applied as an electrode for a vanadium redox flow battery (VRFB). The physical and electrochemical analyses demonstrate that the oxygen groups facilitate nitrogen doping in the carbon felt. Carbon felt (J5O3+NH3), which was subjected to ammonia heat treatment after ozone treatment, showed higher oxygen and nitrogen contents than carbon felt (J5NH3+O3), which was subjected to ammonia heat treatment first and then ozone treatment. From the charging/discharging of VRFB, the J5O3+NH3 carbon felt electrode showed 14.4 Ah/L discharge capacity at a current density of 150 mA /cm², which was 15% and 33% higher than that of J5NH3+O3 and non-activated carbon felt (J5), respectively. These results show that ozone and ammonia sequential treatment is an effective carbon felt activation method to increase the performance of the vanadium redox flow battery.

• 에너지공학
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• 제24권3호
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• pp.89-95
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• 2015

레독스흐름전지의 전극으로 사용하기 위해 (주)CNF에서 제조한 탄소펠트를 여러 가지 온도에서 열처리하여 실험하였다. 열처리 조건에 따른 탄소펠트의 물성특성을 파악하기 위하여 BET(비표면적)와 무게감소를 측정하였고 표면특성을 살펴보기 위하여 주사전자현미경(SEM)과 XPS 분석을 실시하였다. 또한 전기저항, CV(cyclic voltammetry), RFB 충방전 성능 통해 열처리 조건에 따른 전극특성에 미치는 영향을 살펴보았다. SEM, BET분석을 통하여 탄소펠트 표면의 물성 변화를 확인하였고, XPS 분석을 통해 $550^{\circ}C$에서 1시간 열처리한 탄소펠트의 표면에 산소 관능기가 가장 많이 부가된 것을 확인하였다. CV 실험을 수행한 결과 $550^{\circ}C$ 열처리 전극의 활성면적이 가장 컸다. $400^{\circ}C$, $500^{\circ}C$, $550^{\circ}C$에서 열처리한 탄소펠트를 이용하여 바나듐 레독스흐름전지를 구성하고 충-방전 실험을 실시한 결과 충-방전 에너지효율이 $400^{\circ}C$ 열처리 전극의 경우 72.9%, $500^{\circ}C$ 열처리 전극의 경우 79.8%, $550^{\circ}C$ 열처리 전극의 경우 79.8%로 $550^{\circ}C$ 열처리 전극이 가장 우수하였다.

• 한국수소및신에너지학회논문집
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• 제26권4호
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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.

• 한국수소및신에너지학회논문집
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• 제22권5호
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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.