Solid State Proton Conductors

Philippe Knauth is Professor and Director of the Laboratoire Chimie Provence, University of Provence, Marseille, France.He has published 6 books, 2 European and 2 US patents, 200 publications, including 95 papers in international journals and 35 invited/plenary talks at international conferences.Maria Luisa Di Vona is Assistant Professor in Chemistry at the Dipartimento di Scienze e Tecnologie Chimiche, Universita Degli Studi di RomaTor Veragata, Rome, Italy. She is also Visiting Professor at the University of Provence.Author of 100 publications, including 67 in international journals, 2 book chapters , 1 book (Electroceramics VIII-2002).Di Vona and Knauth were organizers of the 2009 E-MRS symposium "Materials for Polymer Electrolyte Membrane Fuel Cells".

• Preface xi About the Editors xiiiContributing Authors xv1 Introduction and Overview: Protons, the Nonconformist Ions 1Maria Luisa Di Vona and Philippe Knauth1.1 Brief History of the Field 21.2 Structure of This Book 2References 42 Morphology and Structure of Solid Acids 5Habib Ghobarkar, Philippe Knauth and Oliver Sch€af2.1 Introduction 52.1.1 Preparation Technique of Solid Acids 52.1.2 Imaging Technique with the Scanning Electron Microscope 62.2 Crystal Morphology and Structure of Solid Acids 82.2.1 Hydrohalic Acids 82.2.2 Main Group Element Oxoacids 102.2.3 Transition Metal Oxoacids 202.2.4 Carboxylic Acids 22References 243 Diffusion in Solid Proton Conductors: Theoretical Aspects and Nuclear Magnetic Resonance Analysis 25Maria Luisa Di Vona, Emanuela Sgreccia and Sebastiano Tosto3.1 Fundamentals of Diffusion 253.1.1 Phenomenology of Diffusion 263.1.2 Solutions of the Diffusion Equation 353.1.3 Diffusion Coefficients and Proton Conduction 373.1.4 Measurement of the Diffusion Coefficient 383.2 Basic Principles of NMR 403.2.1 Description of the Main NMR Techniques Used in Measuring Diffusion Coefficients 423.3 Application of NMR Techniques 473.3.1 Polymeric Proton Conductors 473.3.2 Inorganic Proton Conductors 583.4 Liquid Water Visualization in Proton-Conducting Membranes by Nuclear Magnetic Resonance Imaging 623.5 Conclusions 66References 674 Structure and Diffusivity in Proton-Conducting Membranes Studied by Quasielastic Neutron Scattering 71Rolf Hempelmann4.1 Survey 714.2 Diffusion in Solids and Liquids 734.3 Quasielastic Neutron Scattering: A Brief Introduction 764.4 Proton Diffusion in Membranes 824.4.1 Microstructure by Means of SAXS and SANS 824.4.2 Proton Conductivity and Water Diffusion 894.4.3 QENS Studies 904.5 Solid State Proton Conductors 954.5.1 Aliovalently Doped Perovskites 964.5.2 Hydrogen-Bonded Systems 1014.6 Concluding Remarks 104References 1045 Broadband Dielectric Spectroscopy: A Powerful Tool for the Determination of Charge Transfer Mechanisms in Ion Conductors 109Vito Di Noto, Guinevere A. Giffin, Keti Vezzu`, Matteo Piga and Sandra Lavina5.1 Basic Principles 1105.1.1 The Interaction of Matter with Electromagnetic Fields: The Maxwell Equations 1105.1.2 Electric Response in Terms of e*m ðoÞ, s*m ðoÞ, and Z*mðoÞ 1115.2 Phenomenological Background of Electric Properties in a Time-Dependent Field 1145.2.1 Polarization Events 1145.3 Theory of Dielectric Relaxation 1275.3.1 Dielectric Relaxation Modes of Macromolecular Systems 1295.3.2 A General Equation for the Analysis in the Frequency Domain of s(o) and e(o) 1325.4 Analysis of Electric Spectra 1325.5 Broadband Dielectric Spectroscopy Measurement Techniques 1415.5.1 Measurement Systems 1425.5.2 Contacts 1585.5.3 Calibration 1655.5.4 Calibration in Parallel Plate Methods 1655.5.5 Measurement Accuracy 1725.6 Concluding Remarks 180References 1806 Mechanical and Dynamic Mechanical Analysis of Proton-Conducting Polymers 185Jean-Franc¸ois Chailan, Mustapha Khadhraoui and Philippe Knauth6.1 Introduction 1856.1.1 Molecular Configurations: The Morphology and Microstructure of Polymers 1856.1.2 Molecular Motions 1876.1.3 Glass Transition and Other Molecular Relaxations 1886.2 Methodology of Uniaxial Tensile Tests 1916.2.1 Elasticity and Young’s Modulus E 1926.2.2 Elasticity and Shear Modulus G 1956.2.3 Elasticity and Cohesion Energy 1966.3 Relaxation and Creep of Polymers 1976.3.1 Stress Relaxation of Polymers 1986.3.2 Creep of Polymers 1996.4 Engineering Stress–Strain Curves of Polymers 2016.4.1 True Stress–Strain Curve for Plastic Flow and Toughness of Polymers 2036.4.2 Behavior of Composite Membranes 2046.4.3 Behavior in the Glassy Regime 2056.4.4 Influence of the Rate of Deformation 2066.4.5 Effect of Temperature on Mechanical Properties 2096.4.6 Thermal Strain 2106.5 Stress–Strain Tensile Tests of Proton-Conducting Ionomers 2116.5.1 Influence of Heat Treatment and Cross-Linking 2126.5.2 Behavior of Composites 2146.5.3 Conclusions 2156.6 Dynamic Mechanical Analysis (DMA) of Polymers 2176.6.1 Principle of Measurement 2176.6.2 Molecular Motions and Dynamic Mechanical Properties 2186.6.3 Experimental Considerations: How Does the Instrument Work? 2196.6.4 Parameters of Dynamic Mechanical Analysis 2206.7 The DMA of Proton-Conducting Ionomers 2226.7.1 Perfluorosulfonic Acid Ionomer Membranes 2226.7.2 Nonfluorinated Membranes 2256.7.3 Organic–Inorganic Composite (or Hybrid) Membranes 230Glossary 235References 2367 Ab Initio Modeling of Transport and Structure of Solid State Proton Conductors 241Jeffrey K. Clark II and Stephen J. Paddison7.1 Introduction 2417.2 Theoretical Methods 2447.2.1 Ab Initio Electronic Structure 2447.2.2 Ab Initio Molecular Dynamics (AIMD) 2487.2.3 Empirical Valence Bond (EVB) Models 2497.3 Polymer Electrolyte Membranes 2517.3.1 Local Microstructure 2517.3.2 Proton Dissociation, Transfer, and Separation 2587.4 Crystalline Proton Conductors and Oxides 2797.4.1 Crystalline Proton Conductors 2797.4.2 Oxides 2847.5 Concluding Remarks 290References 2908 Perfluorinated Sulfonic Acids as Proton Conductor Membranes 295Giulio Alberti, Riccardo Narducci and Maria Luisa Di Vona8.1 Introduction on Polymer Electrolyte Membranes for Fuel Cells 2958.2 General Properties of Polymer Electrolyte Membranes 2968.2.1 Ion Exchange of Polymers Electrolytes in H þ Form 2978.3 Perfluorinated Membranes Containing Superacid –SO3H Groups 3038.3.1 Nafion Preparation 3048.3.2 Nafion Morphology 3048.3.3 Nafion Water Uptake in Liquid Water at Different Temperatures 3068.3.4 Water-Vapor Sorption Isotherms of Nafion 3078.3.5 Curves T/nc for Nafion 117 Membranes in H þ Form 3088.3.6 Water Uptake and Tensile Modulus of Nafion 3118.3.7 Colligative Properties of Inner Proton Solutions in Nafion 3138.3.8 Thermal Annealing of Nafion 3158.3.9 MCPI Method 3158.3.10 Proton Conductivity of Nafion 3198.4 Some Information on Dow and on Recent AquivionIonomers 3218.5 Instability of Proton Conductivity of Highly Hydrated PFSA Membranes 3218.6 Composite Nafion Membranes 3238.6.1 Silica-Filled Ionomer Membranes 3238.6.2 Metal Oxide-Filled Nafion Membranes 3248.6.3 Layered Zirconium Phosphate- and Zirconium Phosphonate-Filled Ionomer Membranes 3248.6.4 Heteropolyacid-Filled Membranes 3258.7 Some Final Remarks and Conclusions 326References 3279 Proton Conductivity of Aromatic Polymers 331Baijun Liu and Michael D. Guiver9.1 Introduction 3319.2 Synthetic Strategies of the Various Acid-Functionalized Aromatic Polymers with Proton Transport Ability 3329.2.1 Sulfonated Poly(arylene ether)s 3329.2.2 Sulfonated Polyimides 3419.2.3 Other Aromatic Polymers as PEMs 3449.3 Approaches to Enhance Proton Conductivity 3499.3.1 Nanophase-Separated Microstructures Containing Proton-Conducting Channels 3499.3.2 Replacement of –Ph-SO3H by –CF2 –SO3H 3539.3.3 Synthesis of High-IEC PEMs 3559.3.4 Composite Membranes 3569.4 Balancing Proton Conductivity, Dimensional Stability, and Other Properties 3589.5 Electrochemical Performance of Aromatic Polymers 3619.5.1 PEMFC Performance 3629.5.2 DMFC Performance 3639.6 Summary 363References 36510 Inorganic Solid Proton Conductors 371Philippe Knauth and Maria Luisa Di Vona10.1 Fundamentals of Ionic Conduction in Inorganic Solids 37110.1.1 Defect Concentrations 37210.1.2 Defect Mobilities 37310.1.3 Kr€oger–Vink Nomenclature 37310.1.4 Ionic Conduction in the Bulk: Hopping Model 37610.2 General Considerations on Inorganic Solid Proton Conductors 37810.2.1 Classification of Solid Proton Conductors 37910.3 Low-Dimensional Solid Proton Conductors: Layered and Porous Structures 38110.3.1 b- and b00-Alumina-Type 38110.3.2 Layered Metal Hydrogen Phosphates 38210.3.3 Micro- and Mesoporous Structures 38410.4 Three-Dimensional Solid Proton Conductors: “Quasi-Liquid” Structures 38510.4.1 Solid Acids 38510.4.2 Acid Salts 38510.4.3 Amorphous and Gelled Oxides and Hydroxides 38710.5 Three-Dimensional Solid Proton Conductors: Defect Mechanisms in Oxides 38710.5.1 Perovskite-Type Oxides 38810.5.2 Other Structure Types 39310.6 Conclusion 394References 395Index 399

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