Electrochemical Components

This book focuses on the methods of storage commonly used in hybrid systems. After an introductory chapter reviewing the basics of electrochemistry, Chapter 2 is given over to the storage of electricity in the form of hydrogen. Once hydrogen has been made, we have to be able to convert it back into electricity on demand. This can be done with another energy converter: a fuel cell, the subject of Chapter 3. Such a system is unable to deliver significant dynamics in terms of storage and release of electricity and needs to be supplemented with another solution: a detailed study of supercapacitors is provided in Chapter 4.While the storage systems touched upon in the previous three chapters (hydrogen batteries and supercapacitors) both exhibit advantageous characteristics, at present they are still relatively costly. Thus, the days of the electrochemical accumulator by no means appear to be numbered just yet. This will therefore be the topic of Chapter 5. Finally, on the basis of the elements laid down in the previous chapters, Chapter 6 will focus on electrical hybridization of these storage systems, with a view to enhancing the performance (in terms of energy, lifetime, cost, etc.) of the newly formed system. Aimed at an audience of researchers, industrialists, academics, teachers and students, many exercises, along with corrected solutions, are provided throughout the book. Contents 1. Basic Concepts of Electrochemistry used in Electrical Engineering. 2. Water Electrolyzers. 3. Fuel Cells. 4. Electrical Energy Storage by Supercapacitors. 5. Electrochemical Accumulators. 6. Hybrid Electrical System. About the Authors Marie-Cécile Péra is a Full Professor at the University of Franche-Comte in France and Deputy Director of the FEMTO-ST Institute (CNRS). Her research activities include modeling, control and diagnosis of electric power generation systems (fuel cells – PEMFC and SOFC, supercapacities, batteries) for transportation and stationary applications. She has contributed to more than 180 articles in international journals and conferences. Daniel Hissel is Full Professor at the University of Franche-Comte in France and Director of the Fuel Cell Lab Research Federation (CNRS). He also leads a research team devoted to hybrid electrical systems in the FEMTO-ST Institute (CNRS). He has published more than 250 research papers on modeling, control, diagnostics and prognostics of hybrid electrical systems. Hamid Gualous is Full Professor at the University of Caen Lower Normandy in France and director of the LUSAC laboratory. His current research interests include power electronics, electric energy storage, power and energy systems and energy management. Christophe Turpin is Full Researcher at the CNRS (French National Center for Scientific Research). He is responsible for hydrogen activities within the Laboratory LAPLACE, Toulouse, France. His research activities include the characterization and modeling of fuel cells and electrolyzers, the state of health of these components, and their hybridization with other electrochemical components (ultracapacitors, batteries) within optimized energy systems for stationary and aeronautical applications.

Table of Contents:
Preface xi Chapter 1. Basic Concepts of Electrochemistry used in Electrical Engineering 1 1.1. Introduction 1 1.2. Brief description and principles of operation of electrochemical components 1 1.2.1. Principle of operation 1 1.2.2. Brief description of groups of components 4 1.3. Redox reaction 7 1.4. Chemical energy 9 1.4.1. Enthalpy, entropy and free energy 9 1.4.2. Enthalpy, entropy and free energy of formation 10 1.5. Potential or voltage of an electrode 10 1.6. Reversible potential of a cell 11 1.7. Faradaic current density and the Butler–Volmer equation 13 1.8. Butler–Volmer equation for a whole cell 15 1.9. From the Butler–Volmer equation to the Tafel equation 17 1.10. Faraday’s law 19 1.11. Matter transfer model: Nernst model 20 1.12. Concept of limit current 22 1.13. Expression of the polarization curve 24 1.14. Double-layer capacity 27 1.15. Electrochemical impedance 27 1.16. Reagents and products in the gaseous phase: total pressure, partial pressure, molar fraction and mixture 30 1.17. Corrected exercises 31 1.17.1. Calculation of the variation in enthalpy during the formation of a mole of water 31 1.17.2. Calculation of the variation in entropy for the formation of a mole of water 34 1.17.3. Calculation of the variation in free energy during the formation of a mole of water 36 1.17.4. Calculation of the Nernst potential for a cell in a PEM fuel cell (PEMFC) 38 1.17.5. Faraday equations for a Pb accumulator 39 1.17.6. Calculation of the mass of water consumed by an electrolysis cell  40 Chapter 2. Water Electrolyzers 41 2.1. Introduction 41 2.2. Principles of operation of the main water electrolyzers 44 2.3. History of water electrolysis 46 2.4. Technological elements 51 2.4.1. Alkaline technology 51 2.4.2. PEM technology 56 2.4.3. SO technology 61 2.4.4. Comparison of the three water electrolyzer technologies 64 2.4.5. Specifications of a commercial electrolyzer 65 2.5. Theoretical approach to an electrolyzer 67 2.5.1. Energy-related elements 67 2.5.2. Electrical behavior in the quasi-static state 80 2.5.3. Electrical behavior in the dynamic state with a large signal 95 2.5.4. Electrical behavior in a dynamic state with a small signal (impedance) 100 2.6. Experimental characterization of the electrical behavior of an electrolyzer 104 2.6.1. Polarization curve (quasi-static characterization) 106 2.6.2. Impedance spectroscopy (dynamic small-signal characterization) 108 2.6.3. Current steps 110 2.6.4. Current sweeping (large-signal dynamic characterization) 111 2.6.5. Combining the approaches to characterization (advanced approach) 111 2.7. Procedures for parameterizing the models 112 2.7.1. Minimal combinatorial approach to experimental characterizations 113 2.7.2. Multiple impedance spectra approach 114 2.7.3. Low-frequency multi-sweeping approach 114 2.7.4. Toward an optimal and systematic combinatorial exploitation of the experimental characterizations 115 2.8. Combination with a fuel cell. Concept of the “hydrogen battery” 116 2.8.1. General considerations 117 2.8.2. Static characteristics of an H2/O2 battery 119 2.8.3. Deadband of an H2/O2 battery 120 2.8.4. Brief overview of situation with industrial developments 122 2.9. A few examples of applications for electrolyzers 123 2.9.1. Points about industrial hydrogen production by electrolysis 124 2.9.2. State of the art on applications coupling solar photovoltaic and hydrogen; close examination of the French projects MYRTE, PEPITE and JANUS 126 2.10. Some points about the storage of hydrogen 135 2.11. Conclusions and perspectives 137 2.12. Exercises 137 Chapter 3. Fuel Cells 151 3.1. Introduction 151 3.2. Classification of fuel cell technologies 152 3.2.1. Classification on the basic of the acid/basic medium 153 3.2.2. Classification on the basis of the operating temperature 154 3.2.3. Classification on the basis of the type of electrolyte 154 3.3. Proton Exchange Membrane Fuel Cells (PEMFCs) 157 3.3.1. Constitution 157 3.3.2. Characteristics 160 3.4. Solid Oxide Fuel Cells (SOFCs) 168 3.5. Fuel-cell systems 171 3.5.1. General points 171 3.5.2. PEMFC systems 173 3.5.3. SOFC systems 179 3.6. Applications for fuel cells 180 3.6.1. Mobile applications 181 3.6.2. Stationary applications 183 3.6.3. Applications in transport 184 3.7. Corrected exercises 190 3.7.1. Calculation of the cost of platinum for an electrode 190 3.7.2. Dimensions of a “standard” fuel cell module 191 3.7.3. Calculation of the flowrate of reactant gases entering the cell 191 3.7.4. Calculation of the water content of the air upon input and output of the cell. Calculation of the dew point at the cell output 193 3.7.5. Calculation of the yield of a PEMFC 197 3.7.6. Autonomy of an exploration submarine 198 3.7.7. Power supply to an isolated farm site 199 3.7.8. Fuel-cell generator for a private vehicle 204 Chapter 4. Electrical Energy Storage by Supercapacitors 209 4.1. Introduction 209 4.2. Operation and energy characteristics of EDLCs 211 4.2.1. Structure and operation of supercapacitors 211 4.2.2. Electrical and energetic characterization of supercapacitors 214 4.3. Supercapacitor module sizing 219 4.3.1. Power-based design 220 4.3.2. Dimension design based on the energy stored by the supercapacitor 222 4.3.3. Balancing the supercapacitors 224 4.4. Supercapacitor modeling 226 4.5. DC/DC converter associated with a supercapacitor module 233 4.6. Thermal behavior of supercapacitors 234 4.6.1. Thermal modeling of supercapacitors 235 4.6.2. Modeling by thermal/electrical analogy 237 4.7. Hybrid electricity storage device: the LIC (Lithium Ion Capacitor) 238 4.8. Exercises – statements 240 Chapter 5. Electrochemical Accumulators 253 5.1. Introduction 253 5.2. Lead accumulators 253 5.2.1. Operational principle 253 5.2.2. Advantages and disadvantages to this technology 254 5.3. Nickel accumulators 255 5.3.1. Nickel-Cadmium (Ni-Cd) accumulator 255 5.3.2. Nickel Metal Hydride (Ni-MH) accumulator 256 5.3.3. Nickel-Zinc accumulator 258 5.4. Lithium accumulators 259 5.4.1. Why lithium? 259 5.4.2. Principle of their function 259 5.4.3. Advantages and disadvantages to these technologies 260 5.4.4. Lithium-ion technology 261 5.4.5. Lithium-metal-polymer technology 262 5.4.6. Other technologies 263 5.5. Characteristics of an accumulator or battery 264 5.5.1. Capacity 264 5.5.2. Internal resistance 266 5.5.3. Voltages 267 5.5.4. Energy 268 5.5.5. State of charge of a battery 268 5.6. Modeling of a battery 269 5.6.1. Thévenin model 269 5.6.2. Improved Thévenin model 270 5.6.3. FreedomCar model 271 5.7. Aging of batteries 272 5.8. Exercises 273 Chapter 6. Hybrid Electrical System 277 6.1. Introduction 277 6.2. Definitions 277 6.2.1. General points 277 6.2.2. Particular case of a hybrid electric vehicle 278 6.2.3. Hybrid electric system 279 6.3. Advantages to hybridization 279 6.3.1. Ragone plot 280 6.3.2. Different types of energy? 284 6.3.3. Taking account of non-energy-related criteria in the choice of a hybrid electricity storage solution 287 6.4. Management of the energy flows in a hybrid system 289 6.4.1. Optimization-based strategies 290 6.4.2. Rule-based strategies 291 6.4.3. Criteria for the supervision of the energy flows 292 6.5. Example of application in the domain of transport: the ECCE platform (Evaluation des Composants d’une Chaine de traction Electrique – Evaluation of the Components in an Electric Powertrain) 293 6.6. Corrected exercises 296 6.6.1. Ragone plot of an ideal battery 296 6.6.2. Ragone plot of an ideal capacitor 299 6.6.3. Design of an electric vehicle 302 6.6.4. Energy management in an electric vehicle 306 Bibliography 309 Index 321