Estimation of water layer thickness at the cathode catalyst layer surface of polymer electrolyte fuel cells from diffusion impedance analysis

Takuya Hoshiko, Hironori Nakajima, Toshiaki Konomi, Tatsumi Kitahara

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

We have analysed the diffusion impedance of a polymer electrolyte fuel cell (PEFC) by electro-chemical impedance spectroscopy (EIS). As a result, we derive oxygen diffusion distance δ adjacent to the cathode electrode (catalyst layer) assuming planar oxygen diffusion in a thin water layer unlike the conventional flooded-agglomerate model and gas phase diffusion model in a gas diffusion layer. The experimental results and their analyses show that δ agrees with a value reported from our previous ex-situ measurement. Moreover, δ gives reasonable concentration overpotentials. Increasing current density and gas humidification brings about the growth of δ. It supports that δ corresponds to the thickness of the accumulated product water in liquid state at the cathode electrode. Thus EIS analysis of the diffusion impedance can be used to diagnose the water accumulation at the cathode electrode. This result enables the prediction of the flooding and drying-up of PEFCs and assures their stable operation.

Original languageEnglish
Pages (from-to)1176-1182
Number of pages7
JournalNihon Kikai Gakkai Ronbunshu, B Hen/Transactions of the Japan Society of Mechanical Engineers, Part B
Volume74
Issue number5
Publication statusPublished - May 1 2008

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fuel cells
Fuel cells
surface layers
Cathodes
cathodes
Electrolytes
electrolytes
impedance
catalysts
Catalysts
polymers
Polymers
water
Water
Electrochemical impedance spectroscopy
Electrodes
electrodes
Oxygen
gaseous diffusion
Diffusion in gases

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Mechanical Engineering

Cite this

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abstract = "We have analysed the diffusion impedance of a polymer electrolyte fuel cell (PEFC) by electro-chemical impedance spectroscopy (EIS). As a result, we derive oxygen diffusion distance δ adjacent to the cathode electrode (catalyst layer) assuming planar oxygen diffusion in a thin water layer unlike the conventional flooded-agglomerate model and gas phase diffusion model in a gas diffusion layer. The experimental results and their analyses show that δ agrees with a value reported from our previous ex-situ measurement. Moreover, δ gives reasonable concentration overpotentials. Increasing current density and gas humidification brings about the growth of δ. It supports that δ corresponds to the thickness of the accumulated product water in liquid state at the cathode electrode. Thus EIS analysis of the diffusion impedance can be used to diagnose the water accumulation at the cathode electrode. This result enables the prediction of the flooding and drying-up of PEFCs and assures their stable operation.",
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T1 - Estimation of water layer thickness at the cathode catalyst layer surface of polymer electrolyte fuel cells from diffusion impedance analysis

AU - Hoshiko, Takuya

AU - Nakajima, Hironori

AU - Konomi, Toshiaki

AU - Kitahara, Tatsumi

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N2 - We have analysed the diffusion impedance of a polymer electrolyte fuel cell (PEFC) by electro-chemical impedance spectroscopy (EIS). As a result, we derive oxygen diffusion distance δ adjacent to the cathode electrode (catalyst layer) assuming planar oxygen diffusion in a thin water layer unlike the conventional flooded-agglomerate model and gas phase diffusion model in a gas diffusion layer. The experimental results and their analyses show that δ agrees with a value reported from our previous ex-situ measurement. Moreover, δ gives reasonable concentration overpotentials. Increasing current density and gas humidification brings about the growth of δ. It supports that δ corresponds to the thickness of the accumulated product water in liquid state at the cathode electrode. Thus EIS analysis of the diffusion impedance can be used to diagnose the water accumulation at the cathode electrode. This result enables the prediction of the flooding and drying-up of PEFCs and assures their stable operation.

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