Impedance Spectroscopy E-Book

Vadim F. Lvovich

• Herausgeber: John Wiley & Sons
• Kategorie: Wissenschaft und neue Technologien
• Sprache: Englisch

Seitenzahl: 651

Veröffentlichungsjahr: 2015

Beschreibung

This book presents a balance of theoretical considerations and practical problem solving of electrochemical impedance spectroscopy. This book incorporates the results of the last two decades of research on the theories and applications of impedance spectroscopy, including more detailed reviews of the impedance methods applications in industrial colloids, biomedical sensors and devices, and supercapacitive polymeric films. The book covers all of the topics needed to help readers quickly grasp how to apply their knowledge of impedance spectroscopy methods to their own research problems. It also helps the reader identify whether impedance spectroscopy may be an appropriate method for their particular research problem. This includes understanding how to correctly make impedance measurements, interpret the results, compare results with expected previously published results form similar chemical systems, and use correct mathematical formulas to verify the accuracy of the data. Unique features of the book include theoretical considerations for dealing with modeling, equivalent circuits, and equations in the complex domain, review of impedance instrumentation, best measurement methods for particular systems and alerts to potential sources of errors, equations and circuit diagrams for the most widely used impedance models and applications, figures depicting impedance spectra of typical materials and devices, extensive references to the scientific literature for more information on particular topics and current research, and a review of related techniques and impedance spectroscopy modifications.

Leseprobe

Contents

Cover

Half Title page

Title page

Copyright page

Preface

Chapter 1: Fundamentals of Electrochemical Impedance Spectroscopy

1.1. Concept of Complex Impedance

1.2. Complex Dielectric, Modulus, and Impedance Data Representations

1.3. Electrochemical Experiment: Charge and Material Transport

1.4. Fundamental Ambiguity of Impedance Spectroscopy Analysis

References

Chapter 2: Graphical Representation of Impedance Spectroscopy Data

2.1. Nyquist and Bode Representation of Complex Impedance Data for Ideal Electrical Circuits

2.2. Dielectric Data Representation

References

Chapter 3: Equivalent Circuits Modeling of the Impedance Phenomenon

3.1. Ideal Circuit Elements

3.2. Nonideal Circuit Elements

3.3. Circuit Models for Systems with Two and More Time Constants

References

Chapter 4: Examples of Simple Equivalent Circuit Models

4.1. Basic R-C Circuit

4.2. Basic R|C Circuit

4.3. Randles RSOL - RCT|CDL Circuit

4.4. Debye Dielectric Relaxation (R1 - C1) | C2 Circuit

Chapter 5: Impedance Representation of Bulk Material and Electrode Processes

5.1. Uncompensated Impedance ZOHM

5.2. Bulk Media Impedance–RSOL, RBULK, and CBULK

5.3. Electrochemical Double Layer Capacitance CDL

5.4. Electrochemical Charge-Transfer Resistance RCT

5.5. Electrochemical Sorption Impedance ZSORP

5.6. Mass Transport Impedance

5.7. Mixed Charge-Transfer, Homogeneous, and Diffusion-Controlled Kinetics

References

Chapter 6: Distributed Impedance Models

6.1. Distributed RBULK|CBULK - RINT|CPEDL Circuit Model

6.2. General Impedance Models for Distributed Electrode Processes

6.3. Identification of Frequency Ranges for Conductivity and Permittivity Measurements

References

Chapter 7: Impedance Analysis of Complex Systems

7.1. Dielectric Analysis of Highly Resistive Composite Materials with Particles Conduction

7.2. Dielectric Analysis of Ionic Colloidal Suspensions

7.3. AC Electrokinetics and Dielectrophoretic Spectroscopy of Colloidal Suspensions

7.4. Specific Adsorption and Multistep Heterogeneous Kinetics

7.5. Impedance Kinetics Studies on Porous Electrodes

References

Chapter 8: Impedance Instrumentation, Testing, and Data Validation

8.1. Impedance Test Equipment

8.2. Single-Sine Equipment-Lock-In Amplifier and Frequency-Response Analyzer

8.3. Multiple-Sine Impedance Equipment

8.4. Electrochemical Cells

8.5. Linearity, Causality, Stability, Consistency, and Error Analysis of Impedance Measurements

8.6. Complex Nonlinear Least Squares (CNLLS) Regression Fitting

8.7. Practical Approach to Experimental Impedance Data Collection and Analysis

References

Chapter 9: Selected Examples of EIS Applications: Impedance of Electroactive Polymer Films

9.1. The Field of Electroactive Polymers

9.2. Impedance Analysis of Electrochemically Active Polymer Films

9.3. EIS Models of Conducting Polymer Films

9.4. The future of Electroactive Polymers

References

Chapter 10: Selected Examples of EIS Analysis Applications: Industrial Colloids and Lubricants

10.1. The Field of Industrial Colloids and Lubricants

10.2. Physical and Chemical Properties of Lubricants

10.3. Degradation Modes of Lubricants

10.4. Impedance Analysis of Lubricants

10.5. Equivalent-Circuit Model of Lubricants

References

Chapter 11: EIS Analysis Applications: Cell Suspensions, Protein Adsorption, and Implantable Biomedical Devices

11.1. The Field of Biomedical Impedance Applications

11.2. Analysis of Biological Cell Suspensions by Dielectric, Impedance, and AC Electrokinetic Methods

11.3. Impedance Analysis of Protein Adsorption Kinetics

11.4. Impedance Monitoring of Implanted Devices

References

Chapter 12: Selected Examples of Impedance-Analysis Applications

12.1. Impedance Analysis of Insulating Films and Coatings

12.2. Impedance Analysis of Metallic Paints

12.3. Electrorheological Fluids and Charged Suspensions

12.4 Impedance of Metal-Oxide Films and Alloys

12.5. Li-Ion Kinetics in Alkaline Batteries

12.6. Impedance Analysis of Proton Exchange Mebrane Fuel Cells

12.7. Impedance Corrosion Monitoring

References

Chapter 13: EIS Modifications

13.1. AC Voltammetry

13.2. Potentiodynamic and Fourier-Transform Impedance Spectroscopy

13.3. Nonlinear Higher-Harmonics Impedance Analysis

13.4. Local EIS

13.5. Scanning Photo-Induced Impedance Microscopy (SPIM)

References

Chapter 14: Conclusions and Perspectives of EIS

Abbreviations and Symbols

Index

IMPEDANCE SPECTROSCOPY

Copyright © 2012 by John Wiley & Sons, Inc. All rights reserved

Published by John Wiley & Sons, Inc., Hoboken, New Jersey Published simultaneously in Canada

No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, scanning, or otherwise, except as permitted under Section 107 or 108 of the 1976 United States Copyright Act, without either the prior written permission of the Publisher, or authorization through payment of the appropriate per-copy fee to the Copyright Clearance Center, Inc., 222 Rosewood Drive, Danvers, MA 01923, [phone], fax [phone], or on the web at www.copyright.com. Requests to the Publisher for permission should be addressed to the Permissions Department, John Wiley & Sons, Inc., 111 River Street, Hoboken, NJ 07030, [phone], fax [phone], or online at http://www.wiley.com/go/permission.

Limit of Liability/Disclaimer of Warranty: While the publisher and author have used their best efforts in preparing this book, they make no representations or warranties with respect to the accuracy or completeness of the contents of this book and specifically disclaim any implied warranties of merchantability or fitness for a particular purpose. No warranty may be created or extended by sales representatives or written sales materials. The advice and strategies contained herein may not be suitable for your situation. You should consult with a professional where appropriate. Neither the publisher nor author shall be liable for any loss of profit or any other commercial damages, including but not limited to special, incidental, consequential, or other damages.

For general information on our other products and services or for technical support, please contact our Customer Care Department within the United States at [phone], outside the United States at [phone] or fax [phone].

Wiley also publishes its books in a variety of electronic formats. Some content that appears in print may not be available in electronic formats. For more information about Wiley products, visit our web site at www.wiley.com.

Library of Congress Cataloging-in-Publication Data:

Lvovich, Vadim F., 1967–    Impedance spectroscopy with application to electrochemical and dielectric phenomena / Vadim F. Lvovich.     p. cm.  Includes index.   ISBN 978-0-470-62778-5 (hardback) 1. Impedance spectroscopy. 2. Electrochemistry. 1. Title.   QD116.157L86 2012   543’.4—dc23

2011028940

Preface

Since its conceptual introduction in the late 19th century, the impedance spectroscopy has undergone a tremendous evolution into a rich and vibrant multidisciplinary science. Over the last decade Electrochemical Impedance Spectroscopy (EIS) has become established as one of the most popular analytical tools in materials research. The technique is being widely and effectively applied to a large number of important areas of materials research and analysis, such as corrosion studies and corrosion control; monitoring of properties of electronic and ionic conducting polymers, colloids and coatings; measurements in energy storage, batteries, and fuel cells-related systems; biological analysis and biomedical sensors; measurements in semiconductors and solid electrolytes; studies of electrochemical kinetics, reactions and processes. Impedance spectroscopy is a powerful technique for investigating electrochemical systems and processes. EIS allows to study, among others, such processes as adsorption, charge- and mass-transport, and kinetics of coupled sequential and parallel reactions.

In a broader sense, EIS is an extraordinarily versatile, sensitive, and informative technique broadly applicable to studies of electrochemical kinetics at electrode-media interfaces and determination of conduction mechanisms in various materials through bound or mobile electronic, ionic, semiconductor, and mixed charges. Impedance analysis is fundamentally based on a relatively simple electrical measurement that can be automated and remotely controlled. Its main strength lies in its ability to interrogate relaxation phenomena whose time constants ranging over several orders of magnitude from minutes down to microseconds. In contrast to other analytical techniques, EIS is noninvasive technique that can be used for on-line analysis and diagnostics. The method offers the most powerful on-line and off-line analysis of the status of electrodes, monitors and probes in many different complex time- and space-resolved processes that occur during electrochemical experiments. For instance, the EIS technique has been broadly practiced in the development of sensors for monitoring rates of materials’ degradation, such as metal corrosion and biofouling of implantable medical devices.

EIS is useful as an empirical quality-control procedure that can also be employed to interpret fundamental electrochemical and electronic processes. Experimental impedance results can be correlated with many practically useful chemical, physical, mechanical, and electrical variables. With the current availability of ever evolving automated impedance equipment covering broad frequency and potential ranges, the EIS studies have become increasingly popular as more and more electrochemists, material scientists, and engineers understand the theoretical basis for impedance spectroscopy and gain skill in the impedance data interpretation.

The impedance technique appears destined to play an increasingly important role in fundamental and applied electrochemistry and material science in the coming years. However, broader practical utilization of EIS has been hindered by the lack of comprehensive and cohesive explanation of the theory, measurements, analysis techniques, and types of acquired data for different investigated systems. These factors may be connected with the fact that existing literature reviews of EIS are very often difficult to understand by non-specialists. As will be shown later, the ambiguity of impedance data interpretation and the establishment of direct relationships with practical physical, chemical, electrical, and mechanical parameters constitute the main disadvantages of the technique. These general weaknesses are amplified especially when considering a great variety of practical impedance applications, where a practical investigator or researcher often has to decide if any of the previously known impedance response models and their interpretations are even remotely applicable to the problem in hand. EIS data demonstrate the investigated system’s response to applied alternating or direct electrical fields. It becomes the investigators’ responsibility to convert the electrical data into parameters of interest, whether it is a concentration of bioanalyte, corrosion rate of metal surfaces, performance characteristics of various components of a fuel cell, or rate of oxidative decomposition of polymer films.

As industrial scientist and engineer with career encompassing multiple senior technology and product development positions in leading R&D divisions in Specialty Chemicals, Electronics, BioMedical, and Aerospace industrial corporations, the author has learned over the years to greatly appreciate the investigative power and flexibility of EIS and impedance-based devices in commercial product development. This book was born out of acute need to catalog and explain multiple variations of the EIS data characteristics encountered in many different practical applications. Although the principle behind the method remains the same, the impedance phenomena investigation in different systems presents a widely different data pattern and requires significant variability in the experimental methodology and interpretation strategy to make sense of the results. The EIS experimental data interpretation for both unknown experimental systems, and well-known systems investigated by other (non-electrochemical) means is widely acknowledged to be the main source of the method’s application challenge, often listed at the main impediment to the method’s broader penetration into scientific and technological markets. This book attempts to at least partially standardize the catalog of EIS responses across many practically encountered fields of use and to present a coherent approach to the analysis of experimental results.

This book is intended to serve as a reference on the topic of practical applications of impedance spectroscopy, while also addressing some of the most basic aspects of EIS theory. The theory of the impedance spectroscopy has been presented in great details and with remarkable skill in well-received monographs by J. R. MacDonald, and recently by M. Orazem and B. Tribollet, as well as in many excellent review chapters referenced in this book. There are a number of short courses, several monographs and many independent publications on the impedance spectroscopy. However, the formal courses on the topic are rarely offered in the university settings. At the same time, there is a significant worldwide need to offer independent, direct and comprehensive training on practical applications of the impedance analysis to many industrial scientists and engineers relatively unfamiliar with the EIS theory but eager to apply impedance analysis to address their everyday product development technological challenges. This manuscript emphasizes practical applications of the impedance spectroscopy. This book in based around a catalogue representing a typical impedance data for large variety of established, emerging, and non-conventional experimental systems; relevant mathematical expressions; and physical and chemical interpretation of the experimental results. Many of these events are encountered in the field by industrial scientists and engineers in electrochemistry, physical and analytical chemistry, and chemical engineering.

This book attempts to present a balance of theoretical considerations and practical applications for problem solving in several of the most widely used fields where electrochemical impedance spectroscopy analysis is being employed. The goal was to produce a text that would be useful to both the novice and the expert in EIS. It is primarily intended for industrial researchers (material scientists, analytical and physical chemists, chemical engineers, material researchers), and applications scientists, wishing to understand how to correctly make impedance measurements, interpret the results, compare results with expected previously published results form similar chemical systems, and use correct mathematical formulas to verify the accuracy of the data. A majority of these individuals reside in the specialty chemicals, polymers, colloids, electrochemical renewable energy and power sources, material science, electronics, biomedical, pharmaceutical, personal care and other smaller industries. The book intends to provide a working background for the practical scientist or engineer who wishes to apply EIS as a method of analysis without needing to become an expert electrochemist. With that in mind, both somewhat oversimplified electrochemical models and in-depth analysis of specific topics of common interest are presented. The manuscript covers many of the topics needed to help readers identify whether EIS may be an appropriate method for their particular practical application or research problem. A number of practical examples and graphical representations of the typical data in the most common practical experimental systems are presented. In that respect the book may also be addressed to students and researchers who may found the presented catalog of impedance phenomenological data and the relevant discussions to be of assistance in their introduction to theoretical and practical aspects of electrochemical research.

Starting with general principles, the book emphasizes practical applications of the electrochemical impedance spectroscopy to separate studies of bulk solution and interfacial processes, using of different electrochemical cells and equipment for experimental characterization of different systems. The monograph provides relevant examples of characterization of large variety of materials in electrochemistry, such as polymers, colloids, coatings, biomedical species, metal oxides, corroded metals, solid-state devices, and electrochemical power sources. The book covers many of the topics needed to help readers identify whether impedance spectroscopy may be an appropriate method for their particular research problem.

This book incorporates the results of the last two decades of research on the theories and applications of impedance spectroscopy, including more detailed reviews of the impedance methods applications in industrial colloids, biomedical sensors and devices, and supercapacitive polymeric films. The book is organized so each chapter stands on its own. The book should assist readers to quickly grasp how to apply their new knowledge of impedance spectroscopy methods to their own research problems through the use of features such as:

Equations and circuit diagrams for the most widely used impedance models and applications

Figures depicting impedance spectra of typical materials and devices

Theoretical considerations for dealing with modeling, equivalent circuits, and equations in the complex domain

Best measurement methods for particular systems and alerts to potential sources of errors

Review of impedance instrumentation

Review of related techniques and impedance spectroscopy modifications

Extensive references to the scientific literature for more information on particular topics and current research

It is hoped that the more advanced reader will also find this book valuable as a review and summary of the literature on the subject. Of necessity, compromises have been made between depth, breadth of coverage, and reasonable size. Many of the subjects such as mathematical fundamentals, statistical and error analysis, and a number of topics on electrochemical kinetics and the method theory have been exceptionally well covered in the previous manuscripts dedicated to the impedance spectroscopy. Similarly the book has not been able to accommodate discussions on many techniques that are useful but not widely practiced. While certainly not nearly covering the whole breadth of the impedance analysis universe, the manuscript attempts to provide both a convenient source of EIS theory and applications, as well as illustrations of applications in areas possibly unfamiliar to the reader. The approach is first to review the fundamentals of electrochemical and material transport processes as they are related to the material properties analysis by impedance / modulus / dielectric spectroscopy (Chapter 1), discuss the data representation (Chapter 2) and modeling (Chapter 3) with relevant examples (Chapter 4). Chapter 5 discusses separate components of the impedance circuit, and Chapters 6 and 7 present several typical examples of combining these components into practically encountered complex distributed systems. Chapter 8 is dedicated to the EIS equipment and experimental design. Chapters 9 through 12 are dedicated to detailed discussions of impedance analysis applications to specific experimental systems, representing both well-studied and emerging fields. Chapter 13 offers a brief review of EIS modifications and closely related analytical methods.

I owe thanks to many others who have helped with this project. I am especially grateful to John Wiley & Sons, Inc. and Lone Wolf Enterprises, Ltd. for their conscientious assistance with many details of preparation and production. Over the years many valuable comments and encouragement have been provided by colleagues through the electrochemical community who assured that there would be a demand for this book. I also would like to thank my wife Laura and my son William for affording me the time and freedom required to undertake such a project.

CHAPTER 1

Fundamentals of Electrochemical Impedance Spectroscopy

1.1. Concept of complex impedance

The concept of electrical impedance was first introduced by Oliver Heaviside in the 1880s and was soon afterward developed in terms of vector diagrams and complex numbers representation by A. E. Kennelly and C. P. Steinmetz [1, p. 5]. Since then the technique has gained in exposure and popularity, propelled by a series of scientific advancements in the field of electrochemistry, improvements in instrumentation performance and availability, and increased exposure to an ever-widening range of practical applications.

For example, the development of the double-layer theory by Frumkin and Grahame led to the development of the equivalent circuit (EC) modeling approach to the representation of impedance data by Randles and Warburg. Extended studies of electrochemical reactions coupled with diffusion (Gerisher) and adsorption (Eppelboin) phenomena, effects of porous surfaces on electrochemical kinetics (de Levie), and nonuniform current and potential distribution dispersions (Newman) all resulted in a tremendous expansion of impedance-based investigations addressing these and other similar problems [1]. Along with the development of electrochemical impedance theory, more elaborate mathematical methods for data analysis came into existence, such as Kramers-Kronig relationships and nonlinear complex regression [1, 2]. Transformational advancements in electrochemical equipment and computer technology that have occurred over the last 30 years allowed for digital automated impedance measurements to be performed with significantly higher quality, better control, and more versatility than what was available during the early years of EIS. One can argue that these advancements completely revolutionized the field of impedance spectroscopy (and in a broader sense the field of electrochemistry), allowing the technique to be applicable to an exploding universe of practical applications. Some of these applications, such as dielectric spectroscopy analysis of electrical conduction mechanisms in bulk polymers and biological cell suspensions, have been actively practiced since the 1950s [3, 4]. Others, such as localized studies of surface corrosion kinetics and analysis of the state of biomedical implants, have come into prominence only relatively recently [5, 6, 7, 8].

In spite of the ever-expanding use of EIS in the analysis of practical and experimental systems, impedance (or complex electrical resistance, for a lack of a better term) fundamentally remains a simple concept. Electrical resistance R is related to the ability of a circuit element to resist the flow of electrical current. Ohm’s Law (Eq. 1-1) defines resistance in terms of the ratio between input voltage V and output current I:

(1-1)

While this is a well-known relationship, its use is limited to only one circuit element—the ideal resistor. An ideal resistor follows Ohm’s Law at all current, voltage, and AC frequency levels. The resistor’s characteristic resistance value R [ohm] is independent of AC frequency, and AC current and voltage signals though the ideal resistor are “in phase” with each other. Let us assume that the analyzed sample material is ideally homogeneous and completely fills the volume bounded by two external current conductors (“electrodes”) with a visible area A that are placed apart at uniform distance d, as shown in Figure 1-1. When external voltage V is applied, a uniform current I passes through the sample, and the resistance is defined as:

FIGURE 1-1 Fundamental impedance experiment

(1-2)

where ρ [ohm cm] is the characteristic electrical resistivity of a material, representing its ability to resist the passage of the current. The inverse of resistivity is conductivity σ [1 / (ohm cm)] or [Sm/cm], reflecting the material’s ability to conduct electrical current between two bounding electrodes.

An ideal resistor can be replaced in the circuit by another ideal element that completely rejects any flow of current. This element is referred as an “ideal” capacitor (or “inductor”), which stores magnetic energy created by an applied electric field, formed when two bounding electrodes are separated by a non-conducting (or “dielectric”) medium. The AC current and voltage signals though the ideal capacitor are completely “out of phase” with each other, with current following voltage. The value of the capacitance presented in Farads [F] depends on the area of the electrodes A, the distance between the electrodes d, and the properties of the dielectric medium reflected in a “relative permittivity” parameter ε as:

(1-3)