Internal mobilities and diffusion in an ionic liquid mixture

Céline Merlet (1) , Paul A. Madden (1) , Mathieu Salanne (2)

1 University of Oxford
2 PHENIX - PHysicochimie des Electrolytes et Nanosystèmes InterfaciauX

The internal mobility gives the rate at which one ionic species moves relative to the other species present in an ionic mixture, it mirrors the differential strength of the interactions between different ionic species. In this work we examine the dependence of the internal mobilities of the Li+ and K+ ions on the composition in molten mixtures of LiF and KF. We compare them to the behaviour of the individual diffusion coefficients and the self-exchange velocities, which measure the rate at which an ion separates from its nearest-neighbour coordination shell. The examination is made using molecular dynamics simulations with polarizable, first-principles parameterised interaction potentials which are shown to reproduce the limited available experimental data on the transport properties of these mixtures extremely well. The results confirm that the composition-dependence of the internal mobilities in LiF/KF follows the unusual type-II behaviour, which is not reflected in that of the diffusion coefficients or the self-exchange velocities.

Domaines: Chimie; Chimie théorique et/ou physique

Céline Merlet, Paul A. Madden, Mathieu Salanne. Internal mobilities and diffusion in an ionic liquid mixture. Physical Chemistry Chemical Physics, 2010, 12 (42), pp.14109. ⟨hal-01985971⟩