Quantifying phosphoric acid in high-temperature polymer electrolyte fuel cell components by X-ray tomographic microscopy.

Synchrotron-based X-ray tomographic microscopy is investigated for imaging the local distribution and concentration of phosphoric acid in high-temperature polymer electrolyte fuel cells. Phosphoric acid fills the pores of the macro- and microporous fuel cell components. Its concentration in the fuel cell varies over a wide range (40-100 wt% H3PO4). This renders the quantification and concentration determination challenging. The problem is solved by using propagation-based phase contrast imaging and a referencing method. Fuel cell components with known acid concentrations were used to correlate greyscale values and acid concentrations. Thus calibration curves were established for the gas diffusion layer, catalyst layer and membrane in a non-operating fuel cell. The non-destructive imaging methodology was verified by comparing image-based values for acid content and concentration in the gas diffusion layer with those from chemical analysis.

[1]  D. I. MacDonald,et al.  Density, electrical conductivity, and vapor pressure of concentrated phosphoric acid , 1969 .

[2]  Werner Lehnert,et al.  Redistribution of Phosphoric Acid in Membrane Electrode Assemblies for High Temperature Polymer Electrolyte Fuel Cells , 2009 .

[3]  G. G. Stokes.  "J." , 1890, The New Yale Book of Quotations.

[4]  I. Manke,et al.  Measuring device for synchrotron X-ray imaging and first results of high temperature polymer electro , 2011 .

[5]  T. Schmidt,et al.  Durability and Reliability in High-Temperature Reformed Hydrogen PEFCs , 2006 .

[6]  Der-Tau Chin,et al.  On the conductivity of phosphoric acid electrolyte , 1989 .

[7]  John Banhart,et al.  Synchrotron X-ray tomography for investigations of water distribution in polymer electrolyte membrane fuel cells , 2011 .

[8]  Christoph Hartnig,et al.  On a new degradation mode for high-temperature polymer electrolyte fuel cells: How bipolar plate degradation affects cell performance , 2011 .

[9]  Anders Kaestner,et al.  Evaluation of Neutron Imaging for Measuring Phosphoric Acid Distribution in High Temperature PEFCs , 2014 .

[10]  R. Reed,et al.  Design and Analysis Data—Density of Aqueous Solutions of Phosphoric Acid Measurements at 25°C. , 1955 .

[11]  F. Marone,et al.  Investigation of the Representative Area of the Water Saturation in Gas Diffusion Layers of Polymer Electrolyte Fuel Cells , 2013 .

[12]  Chao-Yang Wang,et al.  Quantification of Liquid Water Saturation in a PEM Fuel Cell Diffusion Medium Using X-ray Microtomography , 2006 .

[13]  M. Mathias,et al.  Measurement of Catalyst Layer Electrolyte Resistance in PEFCs Using Electrochemical Impedance Spectroscopy , 2005 .

[14]  Marco Stampanoni,et al.  Investigation of liquid water in gas diffusion layers of polymer electrolyte fuel cells using X-ray tomographic microscopy , 2011 .

[15]  M. Stampanoni,et al.  Regridding reconstruction algorithm for real-time tomographic imaging , 2012, Journal of synchrotron radiation.

[16]  R. Abela,et al.  Trends in synchrotron-based tomographic imaging: the SLS experience , 2006, SPIE Optics + Photonics.

[17]  S. Wilkins,et al.  Simultaneous phase and amplitude extraction from a single defocused image of a homogeneous object , 2002, Journal of microscopy.

[18]  E. H. Brown,et al.  Vapor Pressure of Phosphoric Acids , 1952 .

[19]  A. Venkatnathan,et al.  Molecular dynamics simulation of phosphoric acid doped monomer of polybenzimidazole: a potential component polymer electrolyte membrane of fuel cell. , 2012, The journal of physical chemistry. B.

[20]  D. Stolten,et al.  Correlation of Synchrotron X-ray Radiography and Electrochemical Impedance Spectroscopy for the Investigation of HT-PEFCs , 2012 .

[21]  Andrew G. Glen,et al.  APPL , 2001 .

[22]  F. Marone,et al.  Progress in In Situ X-Ray Tomographic Microscopy of Liquid Water in Gas Diffusion Layers of PEFC , 2011 .

[23]  Detlef Stolten,et al.  Fuel Cell Science and Engineering, Materials, Processes, Systems and Technology , 2012 .

[24]  J. Banhart,et al.  In-situ synchrotron X-ray radiography on high temperature polymer electrolyte fuel cells , 2010 .

[25]  T. Wydeven.  Electrical Conductivity of Concentrated Phosphoric Acid from 25° to 60° C. , 1966 .

[26]  Brian C. Benicewicz,et al.  Durability Studies of PBI‐based High Temperature PEMFCs , 2008 .

[27]  J. Banhart,et al.  Cross-sectional insight in the water evolution and transport in polymer electrolyte fuel cells , 2008 .