Korean Chemical Engineering Research

The Korean Institute of Chemical Engineers (한국화학공학회)
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Degradation of Polymer Electrolyte Membrane under OCV/Low Humidity Conditions

OCV / 저가습 조건에서 고분자전해질 막 열화

  • Kim, Taehee (Department of Chemical Engineering, Sunchon National University) ;
  • Lee, Junghun (Korea Institute of Energy Research) ;
  • Lee, Ho (Department of Chemical Engineering, Sunchon National University) ;
  • Lim, Tae Won (HMC Eco Technology Research Institute) ;
  • Park, Kwonpil (Department of Chemical Engineering, Sunchon National University)
  • 김태희 (순천대학교 화학공학과) ;
  • 이정훈 (한국에너지기술연구원) ;
  • 이호 (순천대학교 화학공학과) ;
  • 임태원 (현대자동차 환경기술연구소) ;
  • 박권필 (순천대학교 화학공학과)
  • Received : 2007.04.05
  • Accepted : 2007.04.12
  • Published : 2007.08.31
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Abstract

During PEMFC operation, OCV(open circuit voltage) and low humidity conditions accelerate the degradation of perfluorosulfonic acid membrane. There have been no studies that clearly explain why these conditions accelerate the membrane degradation. In this study, the hydrogen permeability through the membrane, I-V polarization of MEA, fluoride emission rate(FER) and $H_2O_2$ concentration in condensed water were measured during cell operation under OCV and low relative humidity(RH). The experimental results were evaluated with oxygen radical mechanism the most commonly known for membrane degradation. It seems that low RH of anode is a good condition for $H{\cdot}$ radical formation on the Pt catalyst and the OCV condition accelerate the $H{\cdot}$ to form $HO_2{\cdot}$ radical attacking the polymer membrane.

고분자전해질 연료전지를 OCV(open circuit voltage)나 저가습 조건하에서 운전하면 고분자전해질 막의 열화 (degradation)가 가속화된다. 그런데 왜 이러한 조건에서 막 열화가 심하게 되는지 명확히 규명한 연구결과들이 없다. 본 연구에서는 OCV/저가습 조건에서 운전 중 막의 수소 투과도, I-V 분극곡선 변화를 측정하고 응축수 내 불소이온 방출 속도(FER)와 셀 내 생성된 과산화수소 농도를 측정하였다. 그리고 기존의 과산화수소와 라디칼에 의한 고분자막 열화 메카니즘이 실험결과를 설명할 수 있는지 비교 검토하였다. OCV/저가습 조건에서 고분자 막 열화가 잘 되는 것은 건조한 anode의 Pt 촉매 상에서 Pt와 수소원자가 결합된 상태 즉 [PtH]로의 반응이 잘 일어나고 이 [PtH]가 OCV 조건에서는 $HO_2{\cdot}$를 형성할 수 있는 조건을 만족하기 때문으로 보인다.

Keywords

Acknowledgement

Supported by : 산업자원부

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