Systematic Studies of the Gas Humidification Effects on Spatial PEMFC Performance Distributions

Tatyana V. Reshetenko, Guido Bender, Keith Bethune, Richard Rocheleau

Research output: Contribution to journalArticlepeer-review

33 Scopus Citations

Abstract

The overall current density that is measured in a proton exchange membrane fuel cell (PEMFC) represents the average of the local reaction rates. The overall and local PEMFC performances are determined by several primary loss mechanisms, namely activation, ohmic, and mass transfer. Spatial performance and loss variabilities are significant and depend on the cell design and operating conditions. A segmented cell system was used to quantify different loss distributions along the gas channel to understand the effects of gas humidification. A reduction in the reactant stream humidification decreased cell performance and resulted in non-uniform distributions of overpotentials and performance along the flow field. Activation and ohmic overpotentials increased with a relative humidity decrease due to insufficient membrane and catalyst layer hydration. The relative humidity of the cathode had a strong impact on the mass transfer overpotential due to a lower oxygen permeability through the dry Nafion film covering the catalyst surface. The mass transfer loss distribution was non-uniform, and the mass transfer overpotential increased for the outlet segments due to the oxygen consumption at the inlet segments, which reduced the oxygen concentration downstream, and a progressive water accumulation from upstream segments. Electrochemical impedance spectroscopy (EIS) and an equivalent electric circuit (EEC) facilitated the analysis and interpretation of the segmented cell data.

Original languageAmerican English
Pages (from-to)220-229
Number of pages10
JournalElectrochimica Acta
Volume69
DOIs
StatePublished - 1 May 2012

NREL Publication Number

  • NREL/JA-5600-55811

Keywords

  • Current distribution
  • Humidification
  • PEMFC
  • Segmented cell
  • Spatial EIS

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