High-Temperature Electrolysis: From Fundamentals to Applications

Description

This reference text provides a detailed guide to high-temperature electrolysis, including the fundamental and materials aspects of solid oxide and protonic ceramic electrolysis cells, considerations at stack and system levels, recent developments, and important combinations of high-temperature electrolysis with other processes. PRELIMS.pdf Preface Editor biographies Werner Sitte Rotraut Merkle List of contributors CH001.pdf Chapter 1 High-temperature electrolysis—general overview 1.1 The need for energy conversion and the storage of sustainable energy 1.1.1 From fossil fuels to sustainable energy 1.1.2 Potential conversion and storage technologies 1.2 Electrolysis cells 1.2.1 Thermodynamics of the electrolysis of H2O and CO2 1.2.2 Types of electrolysis cell 1.3 Useful electrochemical concepts for SOC cells 1.3.1 Example of SOC structure and materials 1.3.2 Types of potentials in SOCs 1.3.3 Non-recognized overpotential types in composite electrodes and MIECs 1.4 Recommendations for future work 1.4.1 Stoichiometry of materials 1.4.2 Impurities and segregations 1.4.3 Leaks 1.5 Outlook Acknowledgments References CH002.pdf Chapter 2 Electrolyte materials for solid oxide electrolysis cells 2.1 Introduction 2.1.1 Definition of a solid oxide electrolysis electrolyte 2.1.2 Requirements for the electrolyte component 2.2 Materials in common use 2.2.1 Zirconia-based electrolytes 2.2.2 Ceria-based electrolytes 2.2.3 Lanthanum gallate-based perovskite electrolytes 2.2.4 New electrolyte compositions 2.3 Electrolyte degradation mechanisms 2.4 Concluding remarks References CH003.pdf Chapter 3 Anode materials for solid oxide electrolysis cells 3.1 Solid oxide electrolysis cell anodes 3.2 Perovskites: a material scientist’s playground 3.2.1 Crystal structure of perovskites 3.2.2 The influence of different A- and B-site ions on selected materials properties 3.3 Diffusion in the solid state 3.3.1 Definitions of diffusion coefficients 3.3.2 Measurement of diffusion coefficients and ionic conductivity 3.3.3 Diffusion coefficients of relevant positrode materials 3.4 Compatibility with electrolyte materials 3.5 Layered rare-earth nickelates 3.5.1 Introduction 3.5.2 Crystal structure 3.5.3 First-order Ruddlesden–Popper phases 3.5.4 Compatibility with electrolyte materials 3.5.5 Higher-order Ruddlesden–Popper phases 3.5.6 SOEC positrode performance 3.6 Concluding remarks Acknowledgments References CH004.pdf Chapter 4 Cathode materials for solid oxide electrolysis cells 4.1 Fuel electrode processes and requirements 4.2 Ni–YSZ cermet electrodes 4.3 Ceramic electrodes 4.3.1 Ceria 4.3.2 Lanthanum chromites 4.3.3 Ferrite oxides 4.3.4 Strontium titanates 4.3.5 Integration of nanostructured electrocatalysts by infiltration 4.3.6 Integration of nanostructured electrodes by exsolution 4.4 Concluding remarks: from the state of the art to advanced materials design References CH005.pdf Chapter 5 Interconnects and coatings 5.1 Introduction 5.2 Theory and characterization methods used to evaluate metallic interconnects 5.2.1 High-temperature oxidation 5.2.2 Volatilization of Cr 5.2.3 Electrical conductivity 5.3 Degradation of interconnects in SOEC atmospheres 5.3.1 Oxygen-rich atmospheres 5.3.2 Hydrogen and hydrogen–steam atmospheres 5.3.3 CO2–CO atmospheres 5.3.4 Other forms of interconnect degradation 5.4 Concluding remarks Acknowledgment References CH006.pdf Chapter 6 Electrode kinetics 6.1 Introduction 6.1.1 Reaction pathways 6.1.2 Model-type thin-film electrodes as a tool to identify reaction pathways 6.2 Three-phase boundary active electrodes 6.2.1 Ni/YSZ as the fuel electrode 6.2.2 Pt/YSZ in an oxygen-containing atmosphere 6.2.3 LaMnO3-based electrodes for oxygen reduction 6.3 Surface active electrodes 6.3.1 The role of electrode defect chemistry in electrode reactions 6.3.2 The meaning of the electrochemical overpotential in the case of mixed-conducting electrodes 6.3.3 Effect of the electrochemical overpotential on a possible surface potential step 6.3.4 Mechanistic picture of oxygen exchange on MIEC oxide electrodes 6.3.5 The effect of chemical evolution of the electrode surface 6.4 Methods used for the characterization of electrode kinetics 6.4.1 Current–voltage curves 6.4.2 Impedance spectroscopy 6.5 Concluding remarks References CH007.pdf Chapter 7 Cell architectures 7.1 Cell geometries 7.1.1 Introduction 7.1.2 Planar cells 7.1.3 Tubular cells 7.2 SOEC configurations 7.2.1 Introduction 7.3 Range of operating conditions 7.4 Mechanical properties 7.5 Concluding remarks References CH008.pdf Chapter 8 Metal-supported cells 8.1 Background and motivation 8.2 The manufacture of metal-supported cells 8.2.1 Materials and processing of metal substrates 8.2.2 The manufacture of metal-supported cells 8.3 Operational statuses of MS-SOECs 8.4 Operational statuses of MS-PCECs 8.5 Specific degradation issues of metal-supported cells 8.5.1 Oxidation of the metal substrate 8.5.2 Interdiffusion 8.5.3 Ni migration 8.5.4 Chromium poisoning of the oxygen electrode 8.6 Concluding remarks Acknowledgments References CH009.pdf Chapter 9 Advanced data analysis 9.1 Introduction 9.2 Electrochemical characterization of SOECs 9.2.1 SOEC testing in general 9.2.2 Electrochemical impedance spectroscopy 9.3 Microstructural analysis and reconstruction 9.3.1 FIB-SEM and μCT 9.3.2 Image processing, segmentation, and reconstruction 9.4 Impedance data analysis 9.4.1 Validity of impedance data 9.4.2 Equivalent circuit modeling 9.4.3 Impedance data deconvolution approaches 9.4.4 DRT-based equivalent circuit modeling and simulation 9.4.5 Correlation of impedance and physicochemically meaningful parameters 9.5 Concluding remarks References CH010.pdf Chapter 10 Long-term stack tests 10.1 Introduction 10.2 General overview of the degradation tests of SOEC stacks 10.3 Long-term SOEC stack tests 10.3.1 Stacks of ESC cells 10.3.2 Stacks of FSC cells 10.4 Degradation mechanisms 10.4.1 Oxidation of the interconnect 10.4.2 Degradation of the YSZ electrolyte 10.4.3 Degradation of the LSC(F) air electrode 10.4.4 Degradation of the Ni-based electrode 10.4.5 Degradation due to contact in stacks 10.5 Concluding remarks References CH011.pdf Chapter 11 Proton and mixed proton/hole-conducting materials for protonic ceramic electrolysis cells 11.1 Introduction 11.2 Proton-conducting oxides 11.2.1 Proton incorporation reaction and thermodynamics 11.2.2 Proton transport 11.2.3 Electronic defects in proton-conducting materials 11.2.4 Grain-boundary properties and processing issues 11.2.5 Material examples 11.3 Mixed proton/hole-conducting materials 11.3.1 Proton incorporation reactions and thermodynamics, defect interactions 11.3.2 Proton transport in triple-conducting perovskites 11.3.3 Electronic conductivity, conflicting trends 11.3.4 Surface oxygen exchange kinetics and mechanism 11.3.5 Materials examples 11.4 Concluding remarks Acknowledgments References CH012.pdf Chapter 12 Thermodynamics, transport, and electrochemistry in protonic ceramic electrolysis cells 12.1 Introduction 12.1.1 SOEC function 12.1.2 PCEC function 12.1.3 Practical tradeoffs 12.2 Electrolyte and electrode compositions 12.3 Faradaic and energy efficiencies 12.4 Electrolyte membrane performance 12.4.1 BCZYYb equilibrium defect chemistry 12.4.2 Defect and charge transport 12.4.3 Half-cell reversible potential and cell voltage 12.4.4 BCZYYb membrane transport performance 12.5 Electrochemical cells 12.5.1 Pore phase gas-phase transport 12.5.2 Charge conservation within the electron-conducting phase 12.5.3 Defect-incorporation chemistry 12.5.4 Charge-transfer chemistry 12.5.5 Parameter fitting 12.5.6 Defect-incorporation rates 12.6 Concluding remarks Acknowledgments References and additional reading CH013.pdf Chapter 13 Tubular protonic ceramic electrolysis cells and direct hydrogen compression 13.1 Introduction 13.1.1 PCEC operating principles 13.1.2 Cell geometries for pressurized operation 13.2 The thermodynamics and kinetics of pressurized PCECs 13.2.1 Cell-level thermodynamics of pressurized operation 13.2.2 Thermodynamics and kinetics of cell components 13.3 Materials, cell architectures, and assembly 13.3.1 Materials for pressurized operation 13.3.2 Tubular cell fabrication and assemblies 13.4 Status of tubular PCEC technology 13.4.1 Ambient-pressure cell testing 13.4.2 Pressurized tubular PCEs 13.4.3 Future prospects for pressurized tubular PCECs 13.5 Concluding remarks Acknowledgments References CH014.pdf Chapter 14 Planar protonic ceramic electrolysis cells for H2 production and CO2 conversion 14.1 H2 production and CO2 conversion in PCECs 14.1.1 PCECs for H2 production 14.1.2 CO2 conversion in PCECs 14.1.3 Thermodynamics of H2O electrolysis and CO2 conversion in PCECs 14.1.4 Advantages of employing PCECs for H2 production and CO2 conversion 14.2 Current progress in the field of PCECs for H2 production and CO2 conversion 14.2.1 PCECs for H2 production 14.2.2 PCECs for CO2 conversion 14.3 Challenges and opportunities of H2 production in protonic ceramic electrochemical cells 14.3.1 Faradaic efficiency of PCECs for H2 production 14.3.2 Long-term durability 14.4 Concluding remarks Acknowledgments References CH015.pdf Chapter 15 Co-solid oxide electrolysis and methanation 15.1 Power-to-Gas as an option for chemical storage of renewable energy 15.2 The fundamentals of catalytic methanation 15.2.1 Methanation reactors 15.2.2 Methanation catalysts 15.2.3 Methanation kinetics 15.3 Thermodynamics of catalytic methanation 15.4 Requirements for the successful methanation of co-SOEC syngas 15.5 Energetic efficiency and the socioeconomic impact of co-SOEC syngas methanation 15.6 Promising plant designs for efficient SNG production 15.7 Concluding remarks References CH016.pdf Chapter 16 CO2 electrolysis 16.1 Introduction and fundamentals 16.1.1 Thermodynamics 16.1.2 Electrode kinetics and cell performance 16.1.3 History 16.2 Degradation 16.2.1 Carbon deposition 16.2.2 Impurities 16.3 Applications 16.3.1 Renewable CO2-to-hydrocarbon fuels and other chemicals 16.3.2 Carbon monoxide production 16.3.3 Oxygen production on Mars (MOXIE) 16.4 Concluding remarks References CH017.pdf Chapter 17 Power-to-ammonia for fertilizers, chemicals, and as an energy vector 17.1 Introduction 17.2 Ammonia’s properties 17.3 Conventional ammonia production today 17.4 Electrified ammonia plant based on low-temperature electrolysis 17.5 Solid-oxide-electrolyzer-based ammonia production 17.6 Novel electrified ammonia plant without an air separation unit 17.7 Techno-economic studies 17.8 The future use of ammonia as an energy vector 17.9 Concluding remarks Appendix A References CH018.pdf Chapter 18 SOEC-based production of e-fuels via the Fischer–Tropsch route 18.1 Power-to-X from a systems perspective 18.2 SOEC-based options for syngas generation for Fischer–Tropsch-based PtL plants 18.2.1 Fischer–Tropsch synthesis process alternatives 18.2.2 Syngas generation by SOEC and rWGS 18.2.3 Syngas generation by co-SOEC 18.2.4 Comparative assessment 18.3 Process integration in SOEC-based PtL plants 18.3.1 Potential CO2 sources 18.3.2 Thermal integration between FT and co-SOEC 18.3.3 Thermal integration in DAC-based PtL plants using co-SOEC for syngas generation 18.3.4 Options for FT crude refining 18.4 Modular technologies that enable decentralized PtL production 18.4.1 Load-adaptable operation of low-temperature DAC in a PtL plant 18.4.2 Load-adaptable operation of SOECs in a PtL plant 18.4.3 Load-adaptable operation of Fischer–Tropsch synthesis reactors 18.4.4 Simplified FT crude refining to synthetic paraffinic kerosene 18.4.5 Integrated PtL plant based on a 250 kW co-SOEC at KIT’s energy lab 2.0 18.5 Concluding remarks Acknowledgments References and additional reading CH019.pdf Chapter 19 Reversible solid oxide cell systems as key elements of achieving flexibility in future energy systems 19.1 Introduction 19.2 The state of research into rSOC systems 19.3 Methodology 19.3.1 Choice of system layouts 19.3.2 Modeling 19.3.3 Round-trip operation of an rSOC system 19.4 Results and discussion of rSOC system behavior 19.4.1 Operational parameters for high efficiency in EC and FC mode 19.4.2 Evaluation of measures to increase efficiency 19.4.3 Round-trip operation and the design of heat exchangers 19.5 Concluding remarks Message I. Understanding the combined influence of operational parameters on the system performance: Message II. Determining the best operating points for the best system performance in different operational modes: Message III. Quantification of efficiency-increasing measures for different system flowsheets: Message IV. Determination of the best system flowsheets, for the use cases of the energy sector and the industry sector, to meet the flexibility demand with best system performance: References CH020.pdf Chapter 20 Economic aspects of power-to-gas 20.1 Market perspectives 20.1.1 Hydrogen and power-to-gas 20.1.2 High-temperature (co-)electrolysis 20.2 Technology cost-reduction potentials 20.2.1 Economies of manufacturing scale 20.2.2 Economies of unit scale 20.2.3 Cost-reduction potentials for high-temperature electrolysis 20.3 Product generation costs 20.3.1 Electricity costs and efficiency impact 20.3.2 Exploitation of by-products and synergy effects 20.3.3 Carbon costs and circular economies 20.4 Concluding remarks Acknowledgment References