Impact of Li, Na and Zn metal cation concentration in EMIM-TFSI ionic liquids on ion clustering, structure and dynamics

Samanvitha Kunigal Vijaya Shankar (1) , Yann Claveau (1) , Tojo Rasoanarivo (1) , Chris Ewels (1) , Jean Le Bideau (1)

1 IMN - Institut des Matériaux de Nantes Jean Rouxel

We use molecular dynamics calculations to investigate the behavior of metal cations (Li, Na and Zn) within ionic liquids (ILs), specifically EMIM-TFSI, and their impact on key properties, particularly focusing on ion-ion correlations and their influence on diffusion and conductivity. The study explores the competition between metal cations and EMIM ions for binding to TFSI and analyzes ion pair dynamics, revealing that metal cation-TFSI pairs exhibit significantly longer lifetimes compared to TFSI-EMIM pairs. This competitive interaction and the increased stability of metal cation-TFSI pairs at higher concentrations leads to reduced ion exchange, resulting in decreased diffusion and conductivity. The observations underscore the importance of ion size and charge in determining their behavior regarding IL dynamics. Overall, this work provides valuable insights for designing ILs with customized properties, particularly in the context of optimizing conductivity and addressing energy storage challenges.

Mots clés: Ionic liquids; Ionic conductivity; Energy storage; EMIM TFSI; Molecular dynamics; Electrolyte

Domaines: Matière Molle [cond-mat.soft]; Matériaux; Science des matériaux [cond-mat.mtrl-sci]; Chimie-Physique [physics.chem-ph]; Physique Numérique [physics.comp-ph]

Samanvitha Kunigal Vijaya Shankar, Yann Claveau, Tojo Rasoanarivo, Chris Ewels, Jean Le Bideau. Impact of Li, Na and Zn metal cation concentration in EMIM-TFSI ionic liquids on ion clustering, structure and dynamics. Physical Chemistry Chemical Physics, 2024, 26, pp.7049-7059. ⟨10.1039/D3CP06315A⟩. ⟨hal-04455542⟩