Table Of Content

Physics S O INTRODUCTION TO L “There is a definite need for a book of this type. … Very few books consider solid I state ionics in one complete volume. … The author can write and communicate D I N complex ideas very well indeed. I would like to have a copy on my bookshelf and T SOLID STATE IONICS I would certainly use the book in my advanced courses.” S R O —Professor Mike Lyons, School of Chemistry and CRANN, Trinity College Dublin, T D A Ireland U PHENOMENOLOGY AND APPLICATIONS T C Introduction to Solid State Ionics: Phenomenology and Applications pres- T E I ents a pedagogical, graduate-level treatment of the science and technology of O I N superionic conductors, also known as fast ion conductors or solid electrolytes. O T Suitable for physics, materials science, and engineering researchers and stu- O N dents, the text emphasizes basic physics and chemistry as well as applications of electrochemical energy materials. I C The book focuses on fundamental phenomenological aspects, including crystal S structure, phonon dispersion, electronic band structure, defects, disorder, non- stoichiometry, non-equilibrium thermodynamics, phase transitions, and statisti- cal mechanics of iono-electron transport. It explains how the design, synthesis, and characterization of materials aid in optimizing diffusion coefficients and ionic conductivities. The author also describes important applications of solid state ionics, including solid state batteries, fuel cells, and electrochemical sensors. C.S. Sunandana is an honorary professor in the School of Physics at the Univer- S sity of Hyderabad. He is a fellow of the Andhra Pradesh Academy of Sciences, U foundation member of the Materials Research Society of India, and a life mem- N ber of the Indian Physics Association. Dr. Sunandana has published more than A 150 research articles in peer-reviewed journals and coauthored three books. He N earned a PhD in physics from the Indian Institute of Technology. His research D interests encompass condensed matter physics and physics of materials. A N A C. S. SUNANDANA K22628 www.crcpress.com K22628_cover.indd 1 10/19/15 2:40 PM INTRODUCTION TO SOLID STATE IONICS PHENOMENOLOGY AND APPLICATIONS INTRODUCTION TO SOLID STATE IONICS PHENOMENOLOGY AND APPLICATIONS C. S. SUNANDANA UNIVERSITY OF HYDERABAD INDIA CRC Press Taylor & Francis Group 6000 Broken Sound Parkway NW, Suite 300 Boca Raton, FL 33487-2742 © 2016 by Taylor & Francis Group, LLC CRC Press is an imprint of Taylor & Francis Group, an Informa business No claim to original U.S. Government works Version Date: 20150603 International Standard Book Number-13: 978-1-4822-2971-4 (eBook - PDF) This book contains information obtained from authentic and highly regarded sources. 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Visit the Taylor & Francis Web site at http://www.taylorandfrancis.com and the CRC Press Web site at http://www.crcpress.com Contents Preface ......................................................................................................................................................xi Author .....................................................................................................................................................xiii 1. What Is Solid State Ionics?..............................................................................................................1 1.1 Perspectives .............................................................................................................................1 1.1.1 The (Un)common Salt ...............................................................................................2 1.1.2 Nature’s Brain Power Source ....................................................................................5 1.1.3 Electrolyte Balance in Human Body ........................................................................8 1.1.4 Mineralogy and History ............................................................................................9 1.1.5 Batterivity ................................................................................................................14 1.2 Ionic Solid State: Home of Defects and Disorders ................................................................17 1.2.1 Metals, Semiconductors, Insulators, and Fast Ion Conductors ................................18 1.2.2 Defects in Ionic Crystals .........................................................................................20 1.2.3 Open Structures, Stuffed Structures, and Sublattices ............................................21 1.2.4 Crystal Lattice, Reciprocal Lattice, and Brillouin Zones ......................................25 1.2.5 Einstein Solids and Debye Solids ...........................................................................30 1.2.6 Electronic Structure ................................................................................................33 1.3 Physics of Ionic Conduction .................................................................................................36 1.3.1 Ion Diffusion ...........................................................................................................37 1.3.2 Conductivity Basics: Ionic, Electronic, and Mixed Conductivities ........................38 1.3.3 Structure–Defect–Ion Dynamics Nexus .................................................................42 1.4 Scope of the Book .................................................................................................................44 1A.1 Appendix ...............................................................................................................................45 1A.1.1 Crystal Symmetry Means Point Groups and Space Groups ...................................45 Problems for Appendix 1A.1 ................................................................................................49 Problems ...........................................................................................................................................50 References .........................................................................................................................................51 2. Solid State Ionic Materials ............................................................................................................53 2.1 Preamble ...............................................................................................................................53 2.2 Perspectives ...........................................................................................................................54 2.3 Phase Diagrams and Phase Stability of Ionic Materials ......................................................57 2.3.1 Thermodynamics ....................................................................................................57 2.3.2 Phase Diagrams ......................................................................................................57 2.3.3 Phase Stability .........................................................................................................71 2.4 Classification of Solid State Ionic Materials ........................................................................77 2.4.1 Li Family .................................................................................................................78 2.4.1.1 Lithium-Ion Composites .........................................................................83 2.4.1.2 Li-Based Glassy Polymers ......................................................................85 2.4.1.3 Li-Ion Glasses and Glass Ceramics ........................................................90 2.4.2 Na Family ................................................................................................................91 2.4.3 Noble Metal Family ................................................................................................93 2.4.4 Oxygen Family ........................................................................................................96 2.4.5 Halogen Family .......................................................................................................98 2.4.6 Proton Family .......................................................................................................105 2.4.7 Mg Family ..............................................................................................................110 v vi Contents 2.5 Phase Transition as a Paradigm of Solid State Ionics ..........................................................110 2.6 Summary ..............................................................................................................................111 Problems ..........................................................................................................................................111 References .......................................................................................................................................114 3. Materials Synthesis .......................................................................................................................119 3.1 Preamble ..............................................................................................................................119 3.2 Bulk Solid State Ionic Materials .........................................................................................120 3.2.1 High-Temperature Solid State Synthesis ..............................................................120 3.2.2 Temperature-Controlled Precipitation as a Strategy for SSI Materials Synthesis .......................................................................................120 3.2.3 Sol–Gel Combustion or Solvothermal Synthesis ..................................................123 3.2.4 Mechanochemical Reaction Synthesis .................................................................125 3.2.5 Hydrothermal Synthesis .........................................................................................132 3.2.6 Microwave Synthesis or Microwave-Assisted Synthesis ......................................139 3.3 Thin-Film Synthesis Technologies ......................................................................................141 3.3.1 Physical Vapor Deposition .....................................................................................141 3.3.1.1 Resistive Thermal Evaporation or Thermal Evaporation by Resistive Heating ...................................................................................141 3.3.1.2 Electron Beam Physical Vapor Deposition ...........................................142 3.3.1.3 RF Magnetron Sputtering .....................................................................144 3.3.1.4 Pulsed Laser Deposition ........................................................................147 3.3.2 Chemical Vapor Deposition ...................................................................................148 3.3.3 Ion-Beam-Assisted Deposition of Thin Films ......................................................150 3.4 Fabrication of the Li-Ion Battery .........................................................................................152 3.4.1 Coin Battery ...........................................................................................................152 3.4.2 Thin-Film Battery Fabrication ...............................................................................152 3.5 Summary .............................................................................................................................154 Problems ..........................................................................................................................................155 References .......................................................................................................................................155 4. Materials Characterization .........................................................................................................157 4.1 Motivation ...........................................................................................................................157 4.1.1 Crystal Structure and Microstructure ...................................................................157 4.1.1.1 EXAFS ..................................................................................................162 4.1.1.2 Neutron Diffraction or Elastic Neutron Scattering ..............................164 4.1.1.3 Electron Microscopy and Diffraction ...................................................174 4.1.1.4 Atomic Force Microscopy ....................................................................180 4.1.2 Diffusion ...............................................................................................................180 4.1.2.1 Basics ....................................................................................................180 4.1.2.2 Conductivity ..........................................................................................188 4.1.2.3 Dielectric Constant Measurement ........................................................190 4.1.2.4 Thermal Conductivity ..........................................................................192 4.1.2.5 Elastic Property Measurements ............................................................195 4.1.3 Thermal Characterization .....................................................................................198 4.1.3.1 Heat Capacity and Thermal Expansion ................................................198 4.1.3.2 Seebeck Coefficient and Hall Coefficient .............................................212 4.1.4 Spectroscopic Characterization .............................................................................215 4.1.4.1 Impedance Spectroscopy .......................................................................215 4.1.4.2 EIS Spectrum Analyzer Software ........................................................220 4.1.4.3 UV–Visible Optical Spectroscopy ........................................................225 Contents vii 4.1.4.4 Photoacoustic Spectroscopy .................................................................230 4.1.4.5 Fourier Transform Infrared (FTIR) Spectroscopy ...............................233 4.1.4.6 Raman Spectroscopy ............................................................................235 4.1.5 Resonance Spectroscopies ....................................................................................239 4.1.5.1 Nuclear Magnetic Resonance (NMR) Spectroscopy ...........................239 4.1.5.2 Electron Paramagnetic Resonance (EPR) Spectroscopy .....................246 4.1.5.3 Mossbauer Spectroscopy or Nuclear Gamma Resonance ....................252 4.2 Devices ................................................................................................................................256 4.2.1 Electrochemical Characterization of the Li-Ion Battery ......................................256 4.2.2 Electrochemical Characterization of Supercapacitors ...........................................261 4.2.3 Characterization of (a) SOFC and (b) Electrochemical Sensor ............................263 4.2.3.1 SOFC Characterization ........................................................................263 4.2.3.2 Sensor Characterization .......................................................................265 4.3 Summary .............................................................................................................................267 Problems .........................................................................................................................................267 References ......................................................................................................................................273 5. Phase Transitions in Solid State Ionic Materials ......................................................................277 5.1 Introduction .........................................................................................................................277 5.2 Models and Theories...........................................................................................................279 5.2.1 O’Reilly Theory of First-Order Superionic Phase Transitions .............................279 5.2.2 Mezrin’s Approach to the Faraday Transition ......................................................282 5.2.3 Coulomb-Driven Transitions in Fluorites .............................................................287 5.2.4 Random Variable Theory of Phase Transitions in AgI .........................................289 5.2.5 Other Models .........................................................................................................291 5.3 Athermal Phase Transitions ................................................................................................292 5.4 Order–Disorder Phase Transitions in Li-Transition Metal Oxides .....................................296 5.4.1 LiCoO and LiMnO .............................................................................................296 2 2 5.4.2 LiMn O ................................................................................................................298 2 4 5.4.2.1 Pressure-Induced Phase Transitions .....................................................302 5.5 Summary .............................................................................................................................305 Problems .........................................................................................................................................305 References ......................................................................................................................................307 6. Phonons .........................................................................................................................................309 6.1 Motivation ...........................................................................................................................309 6.2 Interionic Potential and Force: Basis for Lattice Dynamics ...............................................309 6.3 Phonon Dispersion in Typical Solid State Ionic Materials ..................................................319 6.3.1 Inelastic Scattering of Neutrons ............................................................................320 6.3.2 Basic Lattice Dynamics ........................................................................................323 6.3.3 Lattice Dynamics of Ag and Cu Halides in the Quadrupolar Deformability Model ............................................................................................328 6.3.4 Phonon Dispersion in Li Battery Electrode Materials..........................................340 6.4 Anharmonicity and Its Consequences ................................................................................346 6.5 Optical Phonons in AgI-Type Compounds .........................................................................348 6.5.1 Phonon-Assisted Superionic Conduction ..............................................................356 6.6 The Kramers Problem .........................................................................................................359 6.7 Soft Modes ...........................................................................................................................361 6.8 Summary .............................................................................................................................364 6A.1 Appendix .............................................................................................................................365 Problems .........................................................................................................................................367 References ......................................................................................................................................370 viii Contents 7. Electronic Structure .....................................................................................................................373 7.1 Perspectives .........................................................................................................................373 7.2 Nature of the Superionic Bond ............................................................................................374 7.3 Bond Fluctuations and Phase Transitions ...........................................................................380 7.4 Critical Ionicity Marginal Covalency and Electronic Structure.........................................384 7.4.1 Critical Ionicity and Pseudopotentials ..................................................................384 7.4.2 Marginal Covalency: Tight-Binding Approximation ...........................................393 7.4.3 Electronic Structure in the Tight-Binding Approximation ...................................401 7.5 D ensity Functional Theory of Electronic Structure of Superionic Conductors .................409 7.6 Electron Relaxation in LiFePO ..........................................................................................416 4 7.7 Role of Electronic Structure in 2D and 3D Li and Na Insertion Compounds ....................422 7.8 Summary .............................................................................................................................425 Problems .........................................................................................................................................425 References ......................................................................................................................................430 8. The All Solid State Battery ...........................................................................................................433 8.1 Perspective ...........................................................................................................................433 8.2 Nature’s Own Battery and the Car Battery ..........................................................................435 8.2.1 Nature’s Own Battery ............................................................................................435 8.2.2 Car Battery ............................................................................................................438 8.3 Li+-Ion Physics and Battery Components ...........................................................................441 8.3.1 Cathode .................................................................................................................441 8.3.2 Electrolyte .............................................................................................................444 8.3.2.1 Liquid Electrolytes ...............................................................................444 8.3.2.2 Solid Electrolytes ..................................................................................444 8.3.3 Anode ....................................................................................................................447 8.3.4 Separator ...............................................................................................................449 8.4 Li–Air (Li–Oxygen) Battery ...............................................................................................450 8.5 Thin Film Battery ................................................................................................................453 8.6 The Na+-Ion Battery ............................................................................................................454 8.7 Li+ Polymer Battery ............................................................................................................456 8.8 Advanced Lithium-Ion Battery Technology .......................................................................457 8.9 Batteries for Electrical Vehicles .........................................................................................459 8.10 Summary .............................................................................................................................463 Problems .........................................................................................................................................463 References ......................................................................................................................................466 9. Fuel Cells and Sensors .................................................................................................................467 9.1 Perspective ..........................................................................................................................467 9.2 Fuel Cells ............................................................................................................................467 9.2.1 Chemical to Electrical Energy Converter .............................................................467 9.2.2 Basics of Conversion Process ...............................................................................468 9.2.3 Solid Oxide Fuel Cells ...........................................................................................471 9.2.4 Polymer Electrolyte Membrane Fuel Cells ............................................................476 9.3 Electrochemical Supercapacitors .........................................................................................478 9.4 Electrochemical Sensors .....................................................................................................480 9.5 Outlook ...............................................................................................................................487 9.6 Summary .............................................................................................................................487 Problems .........................................................................................................................................487 References ......................................................................................................................................488 Contents ix 10. Nanoionics .....................................................................................................................................489 10.1 Motivation ...........................................................................................................................489 10.2 What Is Nanoionics? ...........................................................................................................490 10.3 Structure Defects and Conductivity ....................................................................................492 10.4 Thermodynamics and Electrostatics...................................................................................495 10.5 Phase Transitions in Nanoionics .........................................................................................497 10.6 Physics for Devices .............................................................................................................500 10.7 Nanobatteries ......................................................................................................................501 10.8 Superionic Superlattices .....................................................................................................502 10.9 Outlook ...............................................................................................................................506 10A.1 Appendix: Nanothermodynamics or Nonextensive Thermodynamics ..............................508 Problems ..........................................................................................................................................511 References .......................................................................................................................................512 11. In Lieu of an Epilogue ..................................................................................................................515 Ions’ Meet........................................................................................................................................515 Index .......................................................................................................................................................517