This process of solvent exchange is found to be directly correlated to the making and breaking of structures between the lithium-ion and the anion and, consequently, to the conduction mechanism. Additionally, a picosecond time scale process is observed and assigned to the coordination and decoordination of solvent molecules from a lithium-ion solvation shell. Time-resolved studies reveal similar and fast dynamics for the structural motions of solvent molecules in electrolytes composed of linear molecules, while the electrolyte made of cyclic solvent molecules shows slower structural changes as a result of the dimer formation. However, the cyclic carbonate-based electrolyte presents an additional interaction as a result of dimer formation. Our results suggest that the overall structure and the speciation of the three high concentration electrolytes are similar.
In this article, the interactions and motions involved in lithium bis(trifluoromethanesulfonyl)imide in carbonyl-containing solvents are investigated using linear and time-resolved vibrational spectroscopies and computational methods. However, the molecular level knowledge of the structure and dynamics of such an electrolyte system is limited, especially for electrolytes based on typical organic carbonates. Recent studies have shown that limiting the free solvent molecules in the electrolytes prevents the degradation of the battery electrodes.
High concentration lithium electrolytes have been found to be good candidates for high energy density and high voltage lithium batteries.
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