목차

Chapter 1. Introduction 1
1.1 Background 1
1.2 Literature Review 3
1.2.1 Measurement of oxygen transport resistance 3
1.2.2 Analysis of oxygen transport characteristic considering the liquid water saturation 7
1.2.3 Design of the gas diffusion layer for water management 12
1.3 Objective 16
Chapter 2. Oxygen transport and water management in a PEM fuel cell 18
2.1 Oxygen transport 18
2.1.1 Oxygen diffusion in the gas diffusion layer and catalyst layer 18
2.1.2 Oxygen permeation through the ionomer film 21
2.2Water management 31
2.2.1 Under/Over-saturated region criterion 31
2.2.2 Electro-osmosis drag and back diffusion through the membrane 32
2.2.3 Capillary pressure gradient between porous layers 33
Chapter 3. Analysis of oxygen transport resistance at each component of a PEM fuel cell by limiting current method 36
3.1 Experimental method 36
3.1.1 Method to measure the oxygen transport resistance 36
3.1.2 Experimental strategy to separate each component of a PEM fuel cell 37
3.1.3 Experimental condition 38
3.2 Experimental results 45
3.2.1 Calculation of the total oxygen transport resistance 45
3.2.2 Dissection of molecular diffusion 45
3.2.3 Dissection of Knudsen diffusion and ionomer permeation 47
3.2.4 Separation of the oxygen transport resistance in the MPL 48
3.2.5 Separation of the molecular diffusion in the substrate and catalyst layer 49
3.2.6 Contribution on the oxygen transport resistance of the components of a PEM fuel cell 50
3.2.7 Analysis of tortuosity and pore diameter based on the calculated oxygen transport resistance 52
Chapter 4. Analysis of mass transport resistance by electrochemical impedance spectroscopy considering the water condensation 63
4.1 Experimental method 63
4.1.1 Experimental condition 63
4.1.2 Method to analyze the experimental result of electrochemical impedance spectroscopy 64
4.2 Experimental result 73
4.2.1 Electrochemical impedance change with different operating conditions 73
4.2.2 Effect of the MPL on the electrochemical impedance 77
Chapter 5. Effect of pore-size gradient in the substrate of a GDL on the oxygen transport characteristics 88
5.1 Design of gas diffusion layers 88
5.1.1 Design concept for the pore-size gradient structure 88
5.1.2 Visualization of the pore-size gradient structure 89
5.2 Effects of pore-size gradient in the substrate of GDL 97
5.2.1 Change of the oxygen transport resistance 97
5.2.2 Change of the mass transport resistance 97
Chapter 6. Conclusion 105
6.1 Summary 105
6.2 Contribution 108
Bibliography 110
국문초록 119