II. THEORY 5 2.1 Raman spectroscopy 5 2.1.1 Determination of the coordination/solvation numbers 5 2.2 Dielectric relaxation spectroscopy (DRS) 6 2.2.1 Dielectric measurement 6 2.2.2 Spectra analysis 10 2.2.3 Deriving the concentration of ion species 12 2.2.4 Complimentary information to the Raman 14 2.3. Self-diffusivity of the salt 15 2.3.1 Derivation of Dsalt and improved conductivity parameter 15 2.4 Ion conduction mechanism 17 2.4.1 Walden plot 17 2.4.2 Vehicular and hopping conduction 17 2.5 References 19
III. EXPERIMENT 24 3.1 Materials 24 3.2 Ionic conductivity and viscosity 24 3.3 Raman spectroscopy 24 3.4 Dielectric relaxation spectroscopy (DRS) 25 3.5 Pulsed-field Gradient Nuclear magnetic resonance (PFG-NMR) 26 3.6 Density Function Theory (DFT) calculation 27 3.7 References 29
IV. RESULT and DISCUSSION 30 4.1 Single carbonates electrolyte DMC vs. DEC 30 4.1.1 Ionic conductivity, viscosity, and Walden plot 30 4.1.2 Ion speciation by Raman spectroscopy 33 4.1.3 Dielectric properties of solutions 34 4.1.4 Solvent speciation 35 4.1.5 Density functional theory (DFT) calculation 41 4.1.6 Conclusion 46 4.2 Mixed Carbonate electrolytes 47 4.2.1 Ionic conductivity and viscosity 49 4.2.2 A degree of salt dissociation 51 4.2.3 Ion speciation by DRS 55 4.2.4 Solvent speciation 59 4.2.5 Density functional theory (DFT) calculation 62 4.2.6 Conclusion 65 4.3 DMSO-based electrolytes 67 4.3.1 Ionic conductivity, viscosity, and Walden plot 67 4.3.2 Ionic speciation 69 4.3.3 Solvent speciation 75 4.3.4 Ionic conduction 78 4.3.5 Conclusion 82 4.4 Li-ion hopping conduction in Acetonitrile (AN) 83 4.4.1 Ionic conductivity and viscosity 83 4.4.2 Self-diffusion coefficient 84 4.4.3 Solvent and ion speciation 86 4.4.4 Ion conduction mechanism 89 4.4.5 Rate performance in Li-ion batteries 94 4.4.6 Conclusion 97 4.5 References 99
