Dielectric Properties of Ionic Liquids

Preface

Contents

1 Introduction to Ionic Liquids

Abstract

1.1 Synthetic Ways to Ionic Liquids as Source for Possible Impurities

1.2 Liquid Range of Ionic Liquids

1.3 Viscosity of Ionic Liquids

1.4 Density of Ionic Liquids

1.5 Polarity of Ionic Liquids

1.6 New Polymer Materials Derived from Ionic Liquids

References

2 Rotational and Translational Diffusion in Ionic Liquids

Abstract

2.1 Introduction

2.2 Experimental Details

2.3 Results and Discussion

2.3.1 Charge Transport and Dynamic Glass Transition in Ionic Liquids

2.3.2 Elucidating the Correlation Between Characteristic Hopping Lengths and Molecular Volumes of Ionic Liquids

2.4 Conclusions

Acknowledgments

References

3 Femto- to Nanosecond Dynamics in Ionic Liquids: From Single Molecules to Collective Motions

Abstract

3.1 Introduction

3.2 Broadband Dielectric Spectra of Ionic Liquids

3.3 Translation or Rotation—Comparison to Computational Results

3.4 Local Versus Global Dielectric Response—Comparison to Solvation Response

3.5 Balanced Sensitivities—Comparison to Optical Kerr Effect Spectroscopy

3.6 Adding Molecular Specificity—Comparison to Ultrafast Infrared Spectroscopy

3.7 Conclusions

Acknowledgments

References

4 High-Pressure Dielectric Spectroscopy for Studying the Charge Transfer in Ionic Liquids and Solids

Abstract

4.1 Conductivity Measurements Under High-Pressure Conditions. How to Exert Pressure on the Sample?

4.2 Pressure Sensitivity of Ion Dynamics. How Much Pressure Do We Need to “Supercool” Ionic System?

4.3 Thermal and Density Fluctuations to the Temperature Dependence of ?dc at Ambient and Elevated Pressure

4.4 Density Scaling of Ionic Systems

4.5 Relation Between Ion Dynamics and Structural Relaxation at Ambient and Elevated Pressure

4.5.1 Are the Stockes–Einstein and Walden Laws Always Satisfied?

4.5.2 How to Quantify Decoupling Between the Charge Transfer and Structural/Segmental Relaxation in Ionic Conductors?

4.5.3 How to Control the Time Scale Separation Between Charge and Mass Diffusion?

4.6 Conclusions and Perspectives

Acknowledgement

References

5 Glassy Dynamics and Charge Transport in Polymeric Ionic Liquids

Abstract

5.1 Introduction

5.2 Experimental Details

5.3 Results and Discussion

5.4 Conclusion

Acknowledgments

References

6 Ionic Transport and Dielectric Relaxation in Polymer Electrolytes

Abstract

6.1 Introduction

6.2 Dielectric Relaxation in Polymer Electrolytes

6.2.1 Analysis of Dielectric Spectra of Polymer Electrolytes

6.2.1.1 Spectrum Analysis Protocols

6.2.1.2 Analysis of Electrode Polarization: Ion Number Density and Diffusivity

6.2.2 Low Salt Concentration: Emergence of Ionic Mode

6.2.2.1 Pressure Dependence of the Ionic Mode

6.2.2.2 Slow Segmental Relaxation

6.2.2.3 Nature of the Ionic Mode

6.2.3 Emergence of Additional Relaxation Modes at Higher Salt Concentrations

6.3 Ionic Transport in Polymer Electrolytes

6.3.1 Theory of Ionic Mobility in Electrolyte Solutions

6.3.2 Models of Ionic Transport in Polymer Electrolytes

6.3.2.1 Free-Volume Model

6.3.2.2 Dynamic Bond Percolation Model

6.3.3 Coupling and Decoupling Between Conductivity and Polymer Relaxation

6.3.3.1 Observation of Decoupling in Polymer Electrolytes

6.3.3.2 Walden Plot Analysis

6.4 Summary

Acknowledgments

References

7 Electrochemical Double Layers in Ionic Liquids Investigated by Broadband Impedance Spectroscopy and Other Complementary Experimental Techniques

Abstract

7.1 Broadband Impedance Spectroscopy

7.1.1 Introduction

7.1.2 Theory of Impedance Spectroscopy

7.1.3 Practical EIS Pitfalls

7.1.3.1 Cell Design for Three-Electrode Measurements

7.1.3.2 Non-stationary Electrochemical Systems

7.1.3.3 Fitting Algorithms

7.1.4 Application to Metal | IL Interfaces

7.1.4.1 Introduction

7.1.4.2 [Pyrr1,4]FAP

7.1.4.3 [EMIm]FAP

7.1.4.4 Conclusion

7.2 Scanning Tunneling Microscopy

7.2.1 Introduction

7.2.2 Application to Metal | IL Interfaces

7.3 X-Ray Reflectivity

7.3.1 Introduction

7.3.2 Application to Solid | IL Interfaces

7.4 Atomic Force Microscopy

7.4.1 Introduction

7.4.2 AFM for the Investigation of Solid | IL Interfaces

7.5 Surface Force Apparatus

7.5.1 Introduction

7.5.2 SFA Studies of Solid | IL Interfaces

7.6 Surface-Enhanced Raman Spectroscopy (SERS) and Shell-Isolated Nanoparticle-Enhanced Raman Spectroscopy (SHINERS)

7.7 Sum-Frequency Generation (SFG) Vibrational Spectroscopy

References

8 Dielectric Properties of Ionic Liquids at Metal Interfaces: Electrode Polarization, Characteristic Frequencies, Scaling Laws

Abstract

8.1 Introduction

8.2 Materials and Methods

8.2.1 Materials

8.2.2 Methods

8.3 Dielectric Properties of Ionic Liquids: Characteristic Frequencies and Universal Scaling Laws

8.4 Electrode Polarization and Ionic Charge Transport at Metal Interfaces: Theoretical Model

8.4.1 Analytical Calculations

8.4.1.1 The Onset and the Full Development of Electrical Polarization Effects

8.4.1.2 The Inflection Point Fi

8.4.1.3 Electrode Polarization: The Asymptotic Behavior for x ? 0

8.4.1.4 Gradients of Local Dielectric Properties

8.5 The Complex Dielectric Function of Ionic Liquids in the Interfacial Layers at Metal Electrodes

8.6 Conclusions

References

9 Decoupling Between Structural and Conductivity Relaxation in Aprotic Ionic Liquids

Abstract

9.1 Introduction

9.2 Heat Capacity Spectroscopy

9.3 Results

9.3.1 [C6MIm][NTf2]

9.3.2 [C4MIm][NTf2]

9.3.3 [C8MIm][NTf2]

9.4 Summary

Acknowledgment

References

Index