Unraveling Ion Dynamics and Interactions in an Ionic Liquid Electrolyte with a Protonated Anion for Lithium Batteries

The ion associations in two ionic liquid (IL) electrolytes based on the novel asymmetric anion (difluoromethanesulfonyl) (trifluoromethanesulfonyl)imide (DFTFSI) are probed in detail using a combination of nuclear magnetic resonance (NMR) methods [heteronuclear overhauser enhancement spectroscopy (HOESY), relaxation, and diffusion] and molecular dynamics (MD) simulations. The Li HOESY NMR technique and MD simulations give insights into the lithium interactions with the IL anions and cations, while the measured HOESY cross-relaxation rates and MD simulations indicate that the Li-H (anion) proximity disrupts the hydrogen bonding interaction previously observed between the DFTFSI anion and the ether oxygen of the N-methyl-N-methoxyethylpyrrolidinium (C mpy) cation in the pure IL. Preliminary electrochemical behavior shows excellent Li compatibility of the C3mpyr DFTFSI-based IL electrolyte for future lithium-battery applications.

Automated summary

This study investigates ion associations in two ionic liquid electrolytes based on the novel asymmetric anion DFTFSI. The results show that the proximity of Li-H( anion) disrupts the hydrogen bonding interaction between the anion and cation in the IL electrolyte. Additionally, the C3mpyr DFTFSI-based IL electrolyte demonstrates excellent Li compatibility for future lithium-battery applications.