The Chemistry of Membranes Used in Fuel Cells

Examines the important topic of fuel cell science by way of combining membrane design, chemical degradation mechanisms, and stabilization strategies

This book describes the mechanism of membrane degradation and stabilization, as well as the search for stable membranes that can be used in alkaline fuel cells. Arranged in ten chapters, the book presents detailed studies that can help readers understand the attack and degradation mechanisms of polymer membranes and mitigation strategies. Coverage starts from fundamentals and moves to different fuel cell membrane types and methods to profile and analyze them.

The Chemistry of Membranes Used in Fuel Cells: Degradation and Stabilization features chapters on: Fuel Cell Fundamentals: The Evolution of Fuel Cells and their Components; Degradation Mechanism of Perfluorinated Membranes; Ranking the Stability of Perfluorinated Membranes Used in Fuel Cells to Attack by Hydroxyl Radicals; Stabilization Mechanism of Perfluorinated Membranes by Ce(III) and Mn(II); Hydrocarbon Proton Exchange Membranes; Stabilization of Perfluorinated Membranes Using Nanoparticle Additives; Degradation Mechanism in Aquivion Perfluorinated Membranes and Stabilization Strategies; Anion Exchange Membrane Fuel Cells: Synthesis and Stability; In-depth Profiling of Degradation Processes in Nafion Due to Pt Dissolution and Migration into the Membrane; and Quantum Mechanical Calculations of the Degradation Mechanism in Perfluorinated Membranes.

• Brings together aspects of membrane design, chemical degradation mechanisms and stabilization strategies

• Emphasizes chemistry of fuel cells, which is underemphasized in other books

• Includes discussion of fuel cell performance and behavior, analytical profiling methods, and quantum mechanical calculations

The Chemistry of Membranes Used in Fuel Cells is an ideal book for polymer scientists, chemists, chemical engineers, electrochemists, material scientists, energy and electrical engineers, and physicists. It is also important for grad students studying advanced polymers and applications.

Inhalt

Preface xiii

About the Editor xvii

List of Contributors xix

**1 The Evolution of Fuel Cells and Their Components 1
**Thomas A. Zawodzinski, Zhijiang Tang, and Nelly Cantillo

1.1 Overview: A Personal Perspective of Recent Developments 1

1.2 Basics of Fuel Cell Operation 3

1.3 Types of Fuel Cells 5

1.3.1 Phosphoric Acid Fuel Cell 5

1.3.2 Molten Carbonate Fuel Cell and Solid Oxide Fuel Cell 5

1.3.3 Proton Exchange Membranes Fuel Cell 6

1.3.4 Alkaline Fuel Cell 6

1.3.5 Solid Acid Fuel Cell 8

1.4 Low Temperature Fuel Cells: Components 8

1.4.1 Membranes in PEM Systems 9

1.4.2 Electrocatalysts in PEM Systems 11

1.4.2.1 Catalyst Layer Structure in PEM Systems 13

1.5 Summary 16

Acknowledgments 16

References 16

**2 Degradation Mechanism of Perfluorinated Membranes 19
**Marek Danilczuk, Shulamith Schlick, and Frank D. Coms

2.1 Introduction 19

2.2 Fluoride Release Rate 22

2.3 Nuclear Magnetic Resonance 26

2.4 Fourier Transform Infrared Spectroscopy 30

2.5 Electron Spin Resonance 37

2.5.1 Direct ESR Radical Detection in Perfluorinated Membranes 37

2.5.2 Spin Trapping ESR 40

2.5.3 In Situ ESR Fuel Cell 41

2.5.4 Chemical Reactions and Crossover Processes in a Fuel Cell 43

2.5.5 Effect of Membrane Thickness 46

2.6 Conclusions 49

Acknowledgments 51

References 51

**3 Ranking the Stability of Perfluorinated Membranes to Attack by Hydroxyl Radicals 55
**Marek Danilczuk and Shulamith Schlick

3.1 Introduction 55

3.2 The Chemical Stability of Perfluorinated Ionomers 57

3.3 Electron Spin Resonance Studies of PFSAs Exposed to Hydroxyl Radicals 61

3.3.1 Spin?\Trapping ESR 61

3.3.2 Competitive Kinetics: Perfluorinated Ionomers as Competitors for HO• Radicals 62

3.3.3 Ce(III) as Competitor 68

3.4 Conclusions 70

Acknowledgments 72

References 72

**4 Stabilization of Perfluorinated Membranes Using Ce3+ and Mn2+ Redox Scavengers: Mechanisms and Applications 75
**Frank D. Coms, Shulamith Schlick, and Marek Danilczuk

4.1 Introduction 75

4.2 Oxidant Chemistry 76

4.3 Degradation Mechanisms of PFSA 79

4.4 Mitigation of Chemical Degradation by Redox Quenchers 81

4.4.1 Mitigation Mechanisms of Ce3+ and Mn2+ 82

4.4.1.1 Cerium Mitigation and Chain Scission Processes 89

4.4.2 ESR Spin Trapping Studies 89

4.4.3 Oxidative Stress and Ce3+ Mitigation 91

4.4.3.1 MEA Design 96

4.4.4 Cerium Distribution and Migration 97

4.4.5 CeO2 Mitigation 100

4.4.6 Synergistic Mitigation Strategies 101

4.5 Conclusions 103

Acknowledgments 104

References 104

**5 Hydrocarbon Proton Exchange Membranes 107
**Lorenz Gubler and Willem H. Koppenol

5.1 Introduction 107

5.2 Radical Intermediates in Fuel Cells 108

5.3 Hydrocarbon Membranes 114

5.4 Chemical Stabilization by Antioxidants 119

5.4.1 Regenerative Radical Scavenging in PFSA Membranes 119

5.4.2 Hydrocarbon Membranes Doped with Organic Antioxidants 121

5.4.3 Polymer?\Bound Antioxidants 122

5.5 The Challenge of Regeneration 125

5.5.1 Learnings from Mother Nature 125

5.5.2 Approaches for the Fuel Cell 126

5.6 Concluding Remarks 133

References 134

**6 Stabilization of Perfluorinated Membranes Using Nanoparticle Additives 139
**Guanxiong Wang, Javier Parrondo, and Vijay Ramani

6.1 Nanoparticle Additives as a Stabilizer for Perfluorinated Membranes 139

6.2 CeO2 and Modified CeO2 Nanoparticles as FRSs 141 6.3 Platinum?\Supported Cer...