Degradation of Polymer-Electrolyte Membranes in Fuel Cells I. Experimental

cRussian Academy of Sciences, Moscow, Russia In this work, chemical degradation is studied using highly controlled measurements of the fluoride ion release from subscale cells in degrading environments using perfluorosulfonic-acid-based membrane electrode assemblies, primarily with cast, 25 m 1m il thick membranes. Effects of key variables, such as oxygen concentration, relative humidity RH, temperature, and membrane thickness on the fluoride ion emission rate FER are described under open-circuit decay conditions. Some of the observed trends are expected or consistent with previous observations, such as decreasing FER with decreasing temperature and increasing RH. Other trends observed are not expected, such as a logarithmic decrease of FER with oxygen concentration and increasing FER with increasing membrane thickness. Cross-sectional transmission electron microscopy analysis of decayed membranes indicates a surprisingly homogeneous distribution of small Pt particles 3 to 20 nm in diameter, presumably from dissolution and migration from the cathode. The experimental results are consistent with radical generation at these Pt particles from crossover hydrogen and oxygen, subsequent radical migration, and polymer attack. The response of the FER to new experimental conditions in this study suggests that the attack can exist at any plane within the membrane, not just the “Xo” plane of maximum Pt precipitation.

[1]  Kazuhiko Shinohara,et al.  Membrane Degradation Behavior during Open-Circuit Voltage Hold Test , 2007 .

[2]  M. Hein,et al.  In-situ spin trap electron paramagnetic resonance study of fuel cell processes , 2004 .

[3]  Hubert A. Gasteiger,et al.  Instability of Pt ∕ C Electrocatalysts in Proton Exchange Membrane Fuel Cells A Mechanistic Investigation , 2005 .

[4]  Michael H. Santare,et al.  Stresses in Proton Exchange Membranes Due to Hygro-Thermal Loading , 2006 .

[5]  James M. Fenton,et al.  Membrane Degradation Mechanisms in PEMFCs , 2006, ECS Transactions.

[6]  James M. Fenton,et al.  Effect of Catalyst Properties on Membrane Degradation Rate and the Underlying Degradation Mechanism in PEMFCs , 2006 .

[7]  Eiji Endoh,et al.  Degradation study of MEA for PEMFCs under low humidity conditions , 2004 .

[8]  V. Atrazhev,et al.  The potential of catalytic particle in ion exchange membrane , 2007 .

[9]  D. Wilkinson,et al.  Degradation of polymer electrolyte membranes , 2006 .

[10]  Matt Crum,et al.  Effective Testing Matrix for Studying Membrane Durability in PEM Fuel Cells: Part 2. Mechanical Durability and Combined Mechanical and Chemical Durability , 2006 .

[11]  E. Endoh.  Progress of Highly Durable MEA for PEMFC Under High Temperature and Low Humidity Conditions , 2008 .

[12]  Göran Sundholm,et al.  In-situ measurements of gas permeability in fuel cell membranes using a cylindrical microelectrode , 2002 .

[13]  Eiji Endoh,et al.  Degradation study of MEA for PEMFCs under low humidity conditions , 2004 .

[14]  Hartmut Wendt,et al.  Tecnologia de células a combustível , 2000 .

[15]  Hubert A. Gasteiger,et al.  Aspects of the Chemical Degradation of PFSA Ionomers used in PEM Fuel Cells , 2005 .

[16]  Minoru Inaba,et al.  Gas crossover and membrane degradation in polymer electrolyte fuel cells , 2006 .

[17]  James M. Fenton,et al.  Is H2O2 Involved in the Membrane Degradation Mechanism in PEMFC , 2006 .

[18]  Hubert A. Gasteiger,et al.  Determination of Catalyst Unique Parameters for the Oxygen Reduction Reaction in a PEMFC , 2006 .

[19]  Thomas F. Fuller,et al.  PEM Fuel Cell Pt ∕ C Dissolution and Deposition in Nafion Electrolyte , 2007 .

[20]  D. Curtin,et al.  Advanced materials for improved PEMFC performance and life , 2004 .

[21]  Sergei F. Burlatsky,et al.  Aspects of PEMFC Degradation , 2006 .

[22]  Wen Liu,et al.  In Situ Detection of Hydrogen Peroxide in PEM Fuel Cells , 2005 .

[23]  Matt Crum,et al.  Effective Testing Matrix for Studying Membrane Durability in PEM Fuel Cells: Part I. Chemical Durability , 2006 .

[24]  Hubert A. Gasteiger,et al.  Effect of hydrogen and oxygen partial pressure on Pt precipitation within the membrane of PEMFCs , 2007 .

[25]  V. Atrazhev,et al.  Direct Mechanism of OH Radicals Formation in PEM Fuel Cells , 2008 .

[26]  Hubert A. Gasteiger,et al.  Handbook of Fuel Cells , 2010 .

[27]  T. Okada,et al.  Degradation of Perfluorinated Ionomer Membranes for PEM Fuel Cells during Processing with H2O2 , 2006 .

[28]  Hubert A. Gasteiger,et al.  Oxygen reduction on a high-surface area Pt/Vulcan carbon catalyst: a thin-film rotating ring-disk electrode study , 2001 .

[29]  J. Anzai,et al.  Degradation Mechanism of the PFSA Membrane and Influence of Deposited Pt in the Membrane , 2007 .

[30]  K. Reifsnider,et al.  Mechanical Endurance of Polymer Electrolyte Membrane and PEM Fuel Cell Durability , 2006 .

[31]  H. Gasteiger,et al.  Activity benchmarks and requirements for Pt, Pt-alloy, and non-Pt oxygen reduction catalysts for PEMFCs , 2005 .

[32]  F. Maillard,et al.  Detection of Pt z + Ions and Pt Nanoparticles Inside the Membrane of a Used PEMFC , 2007 .

[33]  Robert M. Darling,et al.  Kinetic Model of Platinum Dissolution in PEMFCs , 2003 .

[34]  M. De Francesco,et al.  Nafion degradation in PEFCs from end plate iron contamination , 2003 .