DR. MARK WILD is Senior Production Manager at OXIS Energy, leading a diverse team manufacturing electrolytes and electrodes for Lithium Sulfur pouch cells, but involved in all aspects of developing this new technology. OXIS Energy is a UK SME devoted to the global commercialization of Lithium–Sulfur batteries.DR. GREGORY J. OFFER is Reader in the Department of Mechanical Engineering at Imperial College London. He leads a group of researchers working on understanding and using electrochemical devices.

• Preface xiiiPart I Materials 11 Electrochemical Theory and Physics 3Geraint Minton1.1 Overview of a LiS cell 31.2 The Development of the Cell Voltage 51.2.1 Using the Electrochemical Potential 71.2.2 Electrochemical Reactions 101.2.3 The Electric Double Layer 131.2.4 Reaction Equilibrium 151.2.5 A Finite Electrolyte 171.2.6 The Need for a Second Electrode 171.3 Allowing a Current to Flow 191.3.1 The Reaction Overpotential 201.3.2 The Transport Overpotential 211.3.3 General Comments on the Overpotentials 221.4 Additional Processes Which Define the Behavior of a LiS Cell 221.4.1 Multiple Electrochemical Reactions at One Surface 221.4.2 Chemical Reactions 231.4.3 Species Solubility and Indirect Reaction Effects 251.4.4 Transport Limitations in the Cathode 251.4.5 The Active Surface Area 261.4.6 Precipitate Accumulation 271.4.7 Electrolyte Viscosity, Conductivity, and Species Transport 271.4.8 Side Reactions and SEI Formation at the Anode 281.4.9 Anode Morphological Changes 291.4.10 Polysulfide Shuttle 291.5 Summary 30References 302 Sulfur Cathodes 33Holger Althues, Susanne Dörfler, Sören Thieme, Patrick Strubel and Stefan Kaskel2.1 Cathode Design Criteria 332.1.1 Overview of Cathode Components and Composition 332.1.2 Cathode Design: Role of Electrolyte in Sulfur Cathode Chemistry 342.1.3 Cathode Design: Impact on Energy Density on Cell Level 352.1.4 Cathode Design: Impact on Cycle Life and Self-discharge 362.1.5 Cathode Design: Impact on Rate Capability 372.2 Cathode Materials 372.2.1 Properties of Sulfur 372.2.2 Porous and Nanostructured Carbons as Conductive Cathode Scaffolds 392.2.2.1 Graphite-Like Carbons 392.2.2.2 Synthesis of Graphite-like Carbons 392.2.2.3 Carbon Black 402.2.2.4 Activated Carbons 412.2.2.5 Carbide-Derived Carbon 422.2.2.6 Hard-Template-Assisted Carbon Synthesis 422.2.2.7 Carbon Surface Chemistry 432.2.3 Carbon/Sulfur Composite Cathodes 432.2.3.1 Microporous Carbons 442.2.3.2 Mesoporous Carbons 452.2.3.3 Macroporous Carbons and Nanotube–based Cathode Systems 462.2.3.4 Hierarchical Mesoporous Carbons 472.2.3.5 Hierarchical Microporous Carbons 492.2.3.6 Hollow Carbon Spheres 502.2.3.7 Graphene 512.2.4 Retention of LiPS by Surface Modifications and Coating 512.2.4.1 Metal Oxides as Adsorbents for Lithium Polysulfides 562.3 Cathode Processing 572.3.1 Methods for C/S Composite Preparation 572.3.2 Wet (Organic, Aqueous) and Dry Coating for Cathode Production 582.3.3 Alternative Cathode Support Concepts (Carbon Current Collectors, Binder-free Electrodes) 592.3.4 Processing Perspective for Carbons, Binders, and Additives 592.4 Conclusions 59References 613 Electrolyte for Lithium–Sulfur Batteries 71Marzieh Barghamadi, Mustafa Musameh, Thomas Rüther, Anand I. Bhatt, Anthony F. Hollenkamp and Adam S. Best3.1 The Case for Better Batteries 713.2 Li–S Battery: Origins and Principles 723.3 Solubility of Species and Electrochemistry 743.4 Liquid Electrolyte Solutions 753.5 Modified Liquid Electrolyte Solutions 913.5.1 Variation in Electrolyte Salt Concentration 913.5.2 Mixed Organic–Ionic Liquid Electrolyte Solutions 913.5.3 Ionic Liquid Electrolyte Solutions 933.6 Solid and Solidified Electrolyte Configurations 963.6.1 Polymer Electrolytes 963.6.1.1 Absorbed Liquid/Gelled Electrolyte 963.6.1.2 Solid Polymer Electrolytes 983.6.2 Non-polymer Solid Electrolytes 1003.7 Challenges of the Cathode and Solvent for Device Engineering 1023.7.1 The Cathode Loading Challenge 1023.7.2 Cathode Wetting Challenge 1043.8 Concluding Remarks and Outlook 108References 1114 Anode–Electrolyte Interface 121Mark Wild4.1 Introduction 1214.2 SEI Formation 1214.3 Anode Morphology 1224.4 Polysulfide Shuttle 1234.5 Electrolyte Additives for Stable SEI Formation 1234.6 Barrier Layers on the Anode 1254.7 A Systemic Approach 126References 126Part II Mechanisms 129Reference 1315 Molecular Level Understanding of the Interactions Between Reaction Intermediates of Li–S Energy Storage Systems and Ether Solvents 133Rajeev S. Assary and Larry A. Curtiss5.1 Introduction 1335.2 Computational Details 1355.3 Results and Discussions 1355.3.1 Reactivity of Li–S Intermediates with Dimethoxy Ethane (DME) 1365.3.2 Kinetic Stability of Ethers in the Presence of Lithium Polysulfide 1385.3.3 Linear Fluorinated Ethers 1405.4 Summary and Conclusions 144Acknowledgments 144References 1446 Lithium Sulfide 147Sylwia Walu´s6.1 Introduction 1476.2 Li2S as the End Discharge Product 1486.2.1 General 1486.2.2 Discharge Product: Li2S or Li2S2/Li2S? 1516.2.3 A Survey of Experimental andTheoretical Findings Involving Li2S and Li2S2 Formation and Proposed Reduction Pathways 1536.2.4 Mechanistic Insight into Li2S/Li2S2 Nucleation and Growth 1576.2.5 Strategies to Limit Li2S Precipitation and Enhance the Capacity 1606.2.6 Charge Mechanism and its Difficulties 1616.3 Li2S-Based Cathodes: Toward a Li Ion System 1646.3.1 General 1646.3.2 Initial Activation of Li2S – Mechanism of First Charge 1656.3.3 Recent Developments in Li2S Cathodes for Improved Performances 1716.4 Summary 176References 1767 Degradation in Lithium–Sulfur Batteries 185Rajlakshmi Purkayastha7.1 Introduction 1857.2 Degradation Processes Within a Lithium–Sulfur Cell 1907.2.1 Degradation at Cathode 1907.2.2 Degradation at Anode 1947.2.3 Degradation in Electrolyte 1977.2.4 Degradation Due to Operating Conditions: Temperature, C-Rates, and Pressure 2007.2.5 Degradation Due to Geometry: Scale-Up and Topology 2057.3 Capacity Fade Models 2097.3.1 Dendrite Models 2117.3.2 Equivalent Circuit Network Models 2137.4 Methods of Detecting and Measuring Degradation 2147.4.1 Incremental Capacity Analysis 2157.4.2 Differential Thermal Voltammetry 2157.4.3 Electrochemical Impedance Spectroscopy 2157.4.4 Resistance Curves 2167.4.5 Macroscopic Indicators 2177.5 Methods for Countering Degradation 2187.6 Future Direction 221References 222Part III Modeling 2278 Lithium–Sulfur Model Development 229Teng Zhang, Monica Marinescu and Gregory J. Offer8.1 Introduction 2298.2 Zero-Dimensional Model 2318.2.1 Model Formulation 2318.2.1.1 Electrochemical Reactions 2318.2.1.2 Shuttle and Precipitation 2328.2.1.3 Time Evolution of Species 2338.2.1.4 Model Implementation 2338.2.2 Basic Charge/Discharge Behaviors 2338.3 Modeling Voltage Loss in Li–S Cells 2368.3.1 Electrolyte Resistance 2378.3.2 Anode Potential 2388.3.3 Surface Passivation 2398.3.4 Transport Limitation 2408.4 Higher Dimensional Models 2428.4.1 One-Dimensional Models 2428.4.2 Multi-Scale Models 2448.5 Summary 245References 2469 Battery Management Systems – State Estimation for Lithium–Sulfur Batteries 249Daniel J. Auger, Abbas Fotouhi, Karsten Propp and Stefano Longo9.1 Motivation 2499.1.1 Capacity 2499.1.2 State of Charge (SoC) 2519.1.3 State of Health (SoH) 2519.1.4 Limitations of Existing Battery State Estimation Techniques 2529.1.4.1 SoC Estimation from “Coulomb Counting” 2529.1.4.2 SoC Estimation from Open-Circuit Voltage (OCV) 2539.1.5 Direction of Current Work 2539.2 Experimental Environment for Li–S Algorithm Development 2549.2.1 Pulse Discharge Tests 2559.2.2 Driving Cycle Tests 2559.3 State Estimation Techniques from Control Theory 2569.3.1 Electrochemical Models 2579.3.2 Equivalent Circuit Network (ECN) Models 2589.3.3 Kalman Filters and Their Derivatives 2599.4 State Estimation Techniques from Computer Science 2619.4.1 ANFIS as a Modeling Tool 2619.4.2 Human Knowledge and Fuzzy Inference Systems (FIS) 2639.4.3 Adaptive Neuro-Fuzzy Inference Systems 2669.4.4 State-of-Charge Estimation Using ANFIS 2689.5 Conclusions and Further Directions 269Acknowledgments 270References 270Part IV Application 27310 Commercial Markets for Li–S 275Mark Crittenden10.1 Technology Strengths Meet Market Needs 27510.1.1 Weight 27510.1.2 Safety 27610.1.3 Cost 27610.1.4 Temperature Tolerance 27610.1.5 Shipment and Storage 27710.1.6 Power Characteristics 27710.1.7 Environmentally Friendly Technology (Clean Tech) 27810.1.8 Pressure Tolerance 27810.1.9 Control 27810.2 Electric Aircraft 27810.3 Satellites 28010.4 Cars 28010.5 Buses 28210.6 Trucks 28310.7 Electric Scooter and Electric Bikes 28410.8 Marine 28510.9 Energy Storage 28510.10 Low-Temperature Applications 28610.11 Defense 28610.12 Looking Ahead 28610.13 Conclusion 28711 Battery Engineering 289Gregory J. Offer11.1 Mechanical Considerations 28911.2 Thermal and Electrical Considerations 289References 29212 Case Study 293Paul Brooks12.1 Introduction 29312.2 A Potted History of Eternal Solar Flight 29312.3 Why Has It Been So Difficult? 29512.4 Objectives of HALE UAV 29712.4.1 Stay Above the Cloud 29812.4.2 Stay Above the Wind 29812.4.3 Stay in the Sun 29912.4.4 Year-Round Markets 30012.4.5 Seasonal Markets 30312.4.6 How Valuable Are These Markets and What Does That Mean for the Battery? 30312.5 Worked Example – HALE UAV 30312.6 Cells, Batteries, and Real Life 30512.6.1 Cycle Life, Charge, and Discharge Rates 30512.6.2 Payload 30612.6.3 Avionics 30612.6.4 Temperature 30612.6.5 End-of-Life Performance 30612.6.6 Protection 30612.6.7 Balancing – Useful Capacity 30712.6.8 Summary of Real-World Issues 30712.7 A Quick Aside on Regenerative Fuel Cells 30812.8 So What Do We Need from Our Battery Suppliers? 30912.9 The Challenges for Battery Developers 31012.10 The Answer to the Title 31012.11 Summary 310Acknowledgments 311References 311Index 313

DR. MARK WILD is Senior Production Manager at OXIS Energy, leading a diverse team manufacturing electrolytes and electrodes for Lithium Sulfur pouch cells, but involved in all aspects of developing this new technology. OXIS Energy is a UK SME devoted to the global commercialization of Lithium–Sulfur batteries.DR. GREGORY J. OFFER is Reader in the Department of Mechanical Engineering at Imperial College London. He leads a group of researchers working on understanding and using electrochemical devices.

• Preface xiiiPart I Materials 11 Electrochemical Theory and Physics 3Geraint Minton1.1 Overview of a LiS cell 31.2 The Development of the Cell Voltage 51.2.1 Using the Electrochemical Potential 71.2.2 Electrochemical Reactions 101.2.3 The Electric Double Layer 131.2.4 Reaction Equilibrium 151.2.5 A Finite Electrolyte 171.2.6 The Need for a Second Electrode 171.3 Allowing a Current to Flow 191.3.1 The Reaction Overpotential 201.3.2 The Transport Overpotential 211.3.3 General Comments on the Overpotentials 221.4 Additional Processes Which Define the Behavior of a LiS Cell 221.4.1 Multiple Electrochemical Reactions at One Surface 221.4.2 Chemical Reactions 231.4.3 Species Solubility and Indirect Reaction Effects 251.4.4 Transport Limitations in the Cathode 251.4.5 The Active Surface Area 261.4.6 Precipitate Accumulation 271.4.7 Electrolyte Viscosity, Conductivity, and Species Transport 271.4.8 Side Reactions and SEI Formation at the Anode 281.4.9 Anode Morphological Changes 291.4.10 Polysulfide Shuttle 291.5 Summary 30References 302 Sulfur Cathodes 33Holger Althues, Susanne Dörfler, Sören Thieme, Patrick Strubel and Stefan Kaskel2.1 Cathode Design Criteria 332.1.1 Overview of Cathode Components and Composition 332.1.2 Cathode Design: Role of Electrolyte in Sulfur Cathode Chemistry 342.1.3 Cathode Design: Impact on Energy Density on Cell Level 352.1.4 Cathode Design: Impact on Cycle Life and Self-discharge 362.1.5 Cathode Design: Impact on Rate Capability 372.2 Cathode Materials 372.2.1 Properties of Sulfur 372.2.2 Porous and Nanostructured Carbons as Conductive Cathode Scaffolds 392.2.2.1 Graphite-Like Carbons 392.2.2.2 Synthesis of Graphite-like Carbons 392.2.2.3 Carbon Black 402.2.2.4 Activated Carbons 412.2.2.5 Carbide-Derived Carbon 422.2.2.6 Hard-Template-Assisted Carbon Synthesis 422.2.2.7 Carbon Surface Chemistry 432.2.3 Carbon/Sulfur Composite Cathodes 432.2.3.1 Microporous Carbons 442.2.3.2 Mesoporous Carbons 452.2.3.3 Macroporous Carbons and Nanotube–based Cathode Systems 462.2.3.4 Hierarchical Mesoporous Carbons 472.2.3.5 Hierarchical Microporous Carbons 492.2.3.6 Hollow Carbon Spheres 502.2.3.7 Graphene 512.2.4 Retention of LiPS by Surface Modifications and Coating 512.2.4.1 Metal Oxides as Adsorbents for Lithium Polysulfides 562.3 Cathode Processing 572.3.1 Methods for C/S Composite Preparation 572.3.2 Wet (Organic, Aqueous) and Dry Coating for Cathode Production 582.3.3 Alternative Cathode Support Concepts (Carbon Current Collectors, Binder-free Electrodes) 592.3.4 Processing Perspective for Carbons, Binders, and Additives 592.4 Conclusions 59References 613 Electrolyte for Lithium–Sulfur Batteries 71Marzieh Barghamadi, Mustafa Musameh, Thomas Rüther, Anand I. Bhatt, Anthony F. Hollenkamp and Adam S. Best3.1 The Case for Better Batteries 713.2 Li–S Battery: Origins and Principles 723.3 Solubility of Species and Electrochemistry 743.4 Liquid Electrolyte Solutions 753.5 Modified Liquid Electrolyte Solutions 913.5.1 Variation in Electrolyte Salt Concentration 913.5.2 Mixed Organic–Ionic Liquid Electrolyte Solutions 913.5.3 Ionic Liquid Electrolyte Solutions 933.6 Solid and Solidified Electrolyte Configurations 963.6.1 Polymer Electrolytes 963.6.1.1 Absorbed Liquid/Gelled Electrolyte 963.6.1.2 Solid Polymer Electrolytes 983.6.2 Non-polymer Solid Electrolytes 1003.7 Challenges of the Cathode and Solvent for Device Engineering 1023.7.1 The Cathode Loading Challenge 1023.7.2 Cathode Wetting Challenge 1043.8 Concluding Remarks and Outlook 108References 1114 Anode–Electrolyte Interface 121Mark Wild4.1 Introduction 1214.2 SEI Formation 1214.3 Anode Morphology 1224.4 Polysulfide Shuttle 1234.5 Electrolyte Additives for Stable SEI Formation 1234.6 Barrier Layers on the Anode 1254.7 A Systemic Approach 126References 126Part II Mechanisms 129Reference 1315 Molecular Level Understanding of the Interactions Between Reaction Intermediates of Li–S Energy Storage Systems and Ether Solvents 133Rajeev S. Assary and Larry A. Curtiss5.1 Introduction 1335.2 Computational Details 1355.3 Results and Discussions 1355.3.1 Reactivity of Li–S Intermediates with Dimethoxy Ethane (DME) 1365.3.2 Kinetic Stability of Ethers in the Presence of Lithium Polysulfide 1385.3.3 Linear Fluorinated Ethers 1405.4 Summary and Conclusions 144Acknowledgments 144References 1446 Lithium Sulfide 147Sylwia Walu´s6.1 Introduction 1476.2 Li2S as the End Discharge Product 1486.2.1 General 1486.2.2 Discharge Product: Li2S or Li2S2/Li2S? 1516.2.3 A Survey of Experimental andTheoretical Findings Involving Li2S and Li2S2 Formation and Proposed Reduction Pathways 1536.2.4 Mechanistic Insight into Li2S/Li2S2 Nucleation and Growth 1576.2.5 Strategies to Limit Li2S Precipitation and Enhance the Capacity 1606.2.6 Charge Mechanism and its Difficulties 1616.3 Li2S-Based Cathodes: Toward a Li Ion System 1646.3.1 General 1646.3.2 Initial Activation of Li2S – Mechanism of First Charge 1656.3.3 Recent Developments in Li2S Cathodes for Improved Performances 1716.4 Summary 176References 1767 Degradation in Lithium–Sulfur Batteries 185Rajlakshmi Purkayastha7.1 Introduction 1857.2 Degradation Processes Within a Lithium–Sulfur Cell 1907.2.1 Degradation at Cathode 1907.2.2 Degradation at Anode 1947.2.3 Degradation in Electrolyte 1977.2.4 Degradation Due to Operating Conditions: Temperature, C-Rates, and Pressure 2007.2.5 Degradation Due to Geometry: Scale-Up and Topology 2057.3 Capacity Fade Models 2097.3.1 Dendrite Models 2117.3.2 Equivalent Circuit Network Models 2137.4 Methods of Detecting and Measuring Degradation 2147.4.1 Incremental Capacity Analysis 2157.4.2 Differential Thermal Voltammetry 2157.4.3 Electrochemical Impedance Spectroscopy 2157.4.4 Resistance Curves 2167.4.5 Macroscopic Indicators 2177.5 Methods for Countering Degradation 2187.6 Future Direction 221References 222Part III Modeling 2278 Lithium–Sulfur Model Development 229Teng Zhang, Monica Marinescu and Gregory J. Offer8.1 Introduction 2298.2 Zero-Dimensional Model 2318.2.1 Model Formulation 2318.2.1.1 Electrochemical Reactions 2318.2.1.2 Shuttle and Precipitation 2328.2.1.3 Time Evolution of Species 2338.2.1.4 Model Implementation 2338.2.2 Basic Charge/Discharge Behaviors 2338.3 Modeling Voltage Loss in Li–S Cells 2368.3.1 Electrolyte Resistance 2378.3.2 Anode Potential 2388.3.3 Surface Passivation 2398.3.4 Transport Limitation 2408.4 Higher Dimensional Models 2428.4.1 One-Dimensional Models 2428.4.2 Multi-Scale Models 2448.5 Summary 245References 2469 Battery Management Systems – State Estimation for Lithium–Sulfur Batteries 249Daniel J. Auger, Abbas Fotouhi, Karsten Propp and Stefano Longo9.1 Motivation 2499.1.1 Capacity 2499.1.2 State of Charge (SoC) 2519.1.3 State of Health (SoH) 2519.1.4 Limitations of Existing Battery State Estimation Techniques 2529.1.4.1 SoC Estimation from “Coulomb Counting” 2529.1.4.2 SoC Estimation from Open-Circuit Voltage (OCV) 2539.1.5 Direction of Current Work 2539.2 Experimental Environment for Li–S Algorithm Development 2549.2.1 Pulse Discharge Tests 2559.2.2 Driving Cycle Tests 2559.3 State Estimation Techniques from Control Theory 2569.3.1 Electrochemical Models 2579.3.2 Equivalent Circuit Network (ECN) Models 2589.3.3 Kalman Filters and Their Derivatives 2599.4 State Estimation Techniques from Computer Science 2619.4.1 ANFIS as a Modeling Tool 2619.4.2 Human Knowledge and Fuzzy Inference Systems (FIS) 2639.4.3 Adaptive Neuro-Fuzzy Inference Systems 2669.4.4 State-of-Charge Estimation Using ANFIS 2689.5 Conclusions and Further Directions 269Acknowledgments 270References 270Part IV Application 27310 Commercial Markets for Li–S 275Mark Crittenden10.1 Technology Strengths Meet Market Needs 27510.1.1 Weight 27510.1.2 Safety 27610.1.3 Cost 27610.1.4 Temperature Tolerance 27610.1.5 Shipment and Storage 27710.1.6 Power Characteristics 27710.1.7 Environmentally Friendly Technology (Clean Tech) 27810.1.8 Pressure Tolerance 27810.1.9 Control 27810.2 Electric Aircraft 27810.3 Satellites 28010.4 Cars 28010.5 Buses 28210.6 Trucks 28310.7 Electric Scooter and Electric Bikes 28410.8 Marine 28510.9 Energy Storage 28510.10 Low-Temperature Applications 28610.11 Defense 28610.12 Looking Ahead 28610.13 Conclusion 28711 Battery Engineering 289Gregory J. Offer11.1 Mechanical Considerations 28911.2 Thermal and Electrical Considerations 289References 29212 Case Study 293Paul Brooks12.1 Introduction 29312.2 A Potted History of Eternal Solar Flight 29312.3 Why Has It Been So Difficult? 29512.4 Objectives of HALE UAV 29712.4.1 Stay Above the Cloud 29812.4.2 Stay Above the Wind 29812.4.3 Stay in the Sun 29912.4.4 Year-Round Markets 30012.4.5 Seasonal Markets 30312.4.6 How Valuable Are These Markets and What Does That Mean for the Battery? 30312.5 Worked Example – HALE UAV 30312.6 Cells, Batteries, and Real Life 30512.6.1 Cycle Life, Charge, and Discharge Rates 30512.6.2 Payload 30612.6.3 Avionics 30612.6.4 Temperature 30612.6.5 End-of-Life Performance 30612.6.6 Protection 30612.6.7 Balancing – Useful Capacity 30712.6.8 Summary of Real-World Issues 30712.7 A Quick Aside on Regenerative Fuel Cells 30812.8 So What Do We Need from Our Battery Suppliers? 30912.9 The Challenges for Battery Developers 31012.10 The Answer to the Title 31012.11 Summary 310Acknowledgments 311References 311Index 313

DR. MARK WILD is Senior Production Manager at OXIS Energy, leading a diverse team manufacturing electrolytes and electrodes for Lithium Sulfur pouch cells, but involved in all aspects of developing this new technology. OXIS Energy is a UK SME devoted to the global commercialization of Lithium–Sulfur batteries.DR. GREGORY J. OFFER is Reader in the Department of Mechanical Engineering at Imperial College London. He leads a group of researchers working on understanding and using electrochemical devices.

• Preface xiiiPart I Materials 11 Electrochemical Theory and Physics 3Geraint Minton1.1 Overview of a LiS cell 31.2 The Development of the Cell Voltage 51.2.1 Using the Electrochemical Potential 71.2.2 Electrochemical Reactions 101.2.3 The Electric Double Layer 131.2.4 Reaction Equilibrium 151.2.5 A Finite Electrolyte 171.2.6 The Need for a Second Electrode 171.3 Allowing a Current to Flow 191.3.1 The Reaction Overpotential 201.3.2 The Transport Overpotential 211.3.3 General Comments on the Overpotentials 221.4 Additional Processes Which Define the Behavior of a LiS Cell 221.4.1 Multiple Electrochemical Reactions at One Surface 221.4.2 Chemical Reactions 231.4.3 Species Solubility and Indirect Reaction Effects 251.4.4 Transport Limitations in the Cathode 251.4.5 The Active Surface Area 261.4.6 Precipitate Accumulation 271.4.7 Electrolyte Viscosity, Conductivity, and Species Transport 271.4.8 Side Reactions and SEI Formation at the Anode 281.4.9 Anode Morphological Changes 291.4.10 Polysulfide Shuttle 291.5 Summary 30References 302 Sulfur Cathodes 33Holger Althues, Susanne Dörfler, Sören Thieme, Patrick Strubel and Stefan Kaskel2.1 Cathode Design Criteria 332.1.1 Overview of Cathode Components and Composition 332.1.2 Cathode Design: Role of Electrolyte in Sulfur Cathode Chemistry 342.1.3 Cathode Design: Impact on Energy Density on Cell Level 352.1.4 Cathode Design: Impact on Cycle Life and Self-discharge 362.1.5 Cathode Design: Impact on Rate Capability 372.2 Cathode Materials 372.2.1 Properties of Sulfur 372.2.2 Porous and Nanostructured Carbons as Conductive Cathode Scaffolds 392.2.2.1 Graphite-Like Carbons 392.2.2.2 Synthesis of Graphite-like Carbons 392.2.2.3 Carbon Black 402.2.2.4 Activated Carbons 412.2.2.5 Carbide-Derived Carbon 422.2.2.6 Hard-Template-Assisted Carbon Synthesis 422.2.2.7 Carbon Surface Chemistry 432.2.3 Carbon/Sulfur Composite Cathodes 432.2.3.1 Microporous Carbons 442.2.3.2 Mesoporous Carbons 452.2.3.3 Macroporous Carbons and Nanotube–based Cathode Systems 462.2.3.4 Hierarchical Mesoporous Carbons 472.2.3.5 Hierarchical Microporous Carbons 492.2.3.6 Hollow Carbon Spheres 502.2.3.7 Graphene 512.2.4 Retention of LiPS by Surface Modifications and Coating 512.2.4.1 Metal Oxides as Adsorbents for Lithium Polysulfides 562.3 Cathode Processing 572.3.1 Methods for C/S Composite Preparation 572.3.2 Wet (Organic, Aqueous) and Dry Coating for Cathode Production 582.3.3 Alternative Cathode Support Concepts (Carbon Current Collectors, Binder-free Electrodes) 592.3.4 Processing Perspective for Carbons, Binders, and Additives 592.4 Conclusions 59References 613 Electrolyte for Lithium–Sulfur Batteries 71Marzieh Barghamadi, Mustafa Musameh, Thomas Rüther, Anand I. Bhatt, Anthony F. Hollenkamp and Adam S. Best3.1 The Case for Better Batteries 713.2 Li–S Battery: Origins and Principles 723.3 Solubility of Species and Electrochemistry 743.4 Liquid Electrolyte Solutions 753.5 Modified Liquid Electrolyte Solutions 913.5.1 Variation in Electrolyte Salt Concentration 913.5.2 Mixed Organic–Ionic Liquid Electrolyte Solutions 913.5.3 Ionic Liquid Electrolyte Solutions 933.6 Solid and Solidified Electrolyte Configurations 963.6.1 Polymer Electrolytes 963.6.1.1 Absorbed Liquid/Gelled Electrolyte 963.6.1.2 Solid Polymer Electrolytes 983.6.2 Non-polymer Solid Electrolytes 1003.7 Challenges of the Cathode and Solvent for Device Engineering 1023.7.1 The Cathode Loading Challenge 1023.7.2 Cathode Wetting Challenge 1043.8 Concluding Remarks and Outlook 108References 1114 Anode–Electrolyte Interface 121Mark Wild4.1 Introduction 1214.2 SEI Formation 1214.3 Anode Morphology 1224.4 Polysulfide Shuttle 1234.5 Electrolyte Additives for Stable SEI Formation 1234.6 Barrier Layers on the Anode 1254.7 A Systemic Approach 126References 126Part II Mechanisms 129Reference 1315 Molecular Level Understanding of the Interactions Between Reaction Intermediates of Li–S Energy Storage Systems and Ether Solvents 133Rajeev S. Assary and Larry A. Curtiss5.1 Introduction 1335.2 Computational Details 1355.3 Results and Discussions 1355.3.1 Reactivity of Li–S Intermediates with Dimethoxy Ethane (DME) 1365.3.2 Kinetic Stability of Ethers in the Presence of Lithium Polysulfide 1385.3.3 Linear Fluorinated Ethers 1405.4 Summary and Conclusions 144Acknowledgments 144References 1446 Lithium Sulfide 147Sylwia Walu´s6.1 Introduction 1476.2 Li2S as the End Discharge Product 1486.2.1 General 1486.2.2 Discharge Product: Li2S or Li2S2/Li2S? 1516.2.3 A Survey of Experimental andTheoretical Findings Involving Li2S and Li2S2 Formation and Proposed Reduction Pathways 1536.2.4 Mechanistic Insight into Li2S/Li2S2 Nucleation and Growth 1576.2.5 Strategies to Limit Li2S Precipitation and Enhance the Capacity 1606.2.6 Charge Mechanism and its Difficulties 1616.3 Li2S-Based Cathodes: Toward a Li Ion System 1646.3.1 General 1646.3.2 Initial Activation of Li2S – Mechanism of First Charge 1656.3.3 Recent Developments in Li2S Cathodes for Improved Performances 1716.4 Summary 176References 1767 Degradation in Lithium–Sulfur Batteries 185Rajlakshmi Purkayastha7.1 Introduction 1857.2 Degradation Processes Within a Lithium–Sulfur Cell 1907.2.1 Degradation at Cathode 1907.2.2 Degradation at Anode 1947.2.3 Degradation in Electrolyte 1977.2.4 Degradation Due to Operating Conditions: Temperature, C-Rates, and Pressure 2007.2.5 Degradation Due to Geometry: Scale-Up and Topology 2057.3 Capacity Fade Models 2097.3.1 Dendrite Models 2117.3.2 Equivalent Circuit Network Models 2137.4 Methods of Detecting and Measuring Degradation 2147.4.1 Incremental Capacity Analysis 2157.4.2 Differential Thermal Voltammetry 2157.4.3 Electrochemical Impedance Spectroscopy 2157.4.4 Resistance Curves 2167.4.5 Macroscopic Indicators 2177.5 Methods for Countering Degradation 2187.6 Future Direction 221References 222Part III Modeling 2278 Lithium–Sulfur Model Development 229Teng Zhang, Monica Marinescu and Gregory J. Offer8.1 Introduction 2298.2 Zero-Dimensional Model 2318.2.1 Model Formulation 2318.2.1.1 Electrochemical Reactions 2318.2.1.2 Shuttle and Precipitation 2328.2.1.3 Time Evolution of Species 2338.2.1.4 Model Implementation 2338.2.2 Basic Charge/Discharge Behaviors 2338.3 Modeling Voltage Loss in Li–S Cells 2368.3.1 Electrolyte Resistance 2378.3.2 Anode Potential 2388.3.3 Surface Passivation 2398.3.4 Transport Limitation 2408.4 Higher Dimensional Models 2428.4.1 One-Dimensional Models 2428.4.2 Multi-Scale Models 2448.5 Summary 245References 2469 Battery Management Systems – State Estimation for Lithium–Sulfur Batteries 249Daniel J. Auger, Abbas Fotouhi, Karsten Propp and Stefano Longo9.1 Motivation 2499.1.1 Capacity 2499.1.2 State of Charge (SoC) 2519.1.3 State of Health (SoH) 2519.1.4 Limitations of Existing Battery State Estimation Techniques 2529.1.4.1 SoC Estimation from “Coulomb Counting” 2529.1.4.2 SoC Estimation from Open-Circuit Voltage (OCV) 2539.1.5 Direction of Current Work 2539.2 Experimental Environment for Li–S Algorithm Development 2549.2.1 Pulse Discharge Tests 2559.2.2 Driving Cycle Tests 2559.3 State Estimation Techniques from Control Theory 2569.3.1 Electrochemical Models 2579.3.2 Equivalent Circuit Network (ECN) Models 2589.3.3 Kalman Filters and Their Derivatives 2599.4 State Estimation Techniques from Computer Science 2619.4.1 ANFIS as a Modeling Tool 2619.4.2 Human Knowledge and Fuzzy Inference Systems (FIS) 2639.4.3 Adaptive Neuro-Fuzzy Inference Systems 2669.4.4 State-of-Charge Estimation Using ANFIS 2689.5 Conclusions and Further Directions 269Acknowledgments 270References 270Part IV Application 27310 Commercial Markets for Li–S 275Mark Crittenden10.1 Technology Strengths Meet Market Needs 27510.1.1 Weight 27510.1.2 Safety 27610.1.3 Cost 27610.1.4 Temperature Tolerance 27610.1.5 Shipment and Storage 27710.1.6 Power Characteristics 27710.1.7 Environmentally Friendly Technology (Clean Tech) 27810.1.8 Pressure Tolerance 27810.1.9 Control 27810.2 Electric Aircraft 27810.3 Satellites 28010.4 Cars 28010.5 Buses 28210.6 Trucks 28310.7 Electric Scooter and Electric Bikes 28410.8 Marine 28510.9 Energy Storage 28510.10 Low-Temperature Applications 28610.11 Defense 28610.12 Looking Ahead 28610.13 Conclusion 28711 Battery Engineering 289Gregory J. Offer11.1 Mechanical Considerations 28911.2 Thermal and Electrical Considerations 289References 29212 Case Study 293Paul Brooks12.1 Introduction 29312.2 A Potted History of Eternal Solar Flight 29312.3 Why Has It Been So Difficult? 29512.4 Objectives of HALE UAV 29712.4.1 Stay Above the Cloud 29812.4.2 Stay Above the Wind 29812.4.3 Stay in the Sun 29912.4.4 Year-Round Markets 30012.4.5 Seasonal Markets 30312.4.6 How Valuable Are These Markets and What Does That Mean for the Battery? 30312.5 Worked Example – HALE UAV 30312.6 Cells, Batteries, and Real Life 30512.6.1 Cycle Life, Charge, and Discharge Rates 30512.6.2 Payload 30612.6.3 Avionics 30612.6.4 Temperature 30612.6.5 End-of-Life Performance 30612.6.6 Protection 30612.6.7 Balancing – Useful Capacity 30712.6.8 Summary of Real-World Issues 30712.7 A Quick Aside on Regenerative Fuel Cells 30812.8 So What Do We Need from Our Battery Suppliers? 30912.9 The Challenges for Battery Developers 31012.10 The Answer to the Title 31012.11 Summary 310Acknowledgments 311References 311Index 313