Understanding Lithium Solvation in Ionic Liquids from First Principles Molecular Dynamics Simulations 

Wednesday, October 14, 2015: 12:00
Borein A (Hyatt Regency)
A. Kachmar (Qatar Environment and Energy Research Institute) and M. A. Carignano (Qatar Environment and Energy Research Institute)
Ionic liquids are being considered as an alternative electrolyte for Li-ion batteries. The main reason behind this application is the non-flammability of many ionic liquids that will eliminate one of the major safety issues affecting this technology. In this particular case, we investigate the solvation of lithium (Li) in Ethylammonium Nitrate (EAN). The study relies on a combination of classical, and first principles molecular dynamics simulations using the Gromacs and CP2K software packages, respectively [1,2]. Starting with an existing force field we initially performed a classical simulation in order to obtain a molecular arrangement that was then used as the starting configuration for the first principles simulations. We found that the first principles results give a lower Li-Oxygen average coordination number when compared to recently reported classical simulations [3]. The issue of the discrepancy between classical and first principles predictions for the coordination has been already discussed in the literature for cations solvated in water [4,7]. In particular, our ab-initio simulations conclusively show that only three nitrate molecules solvate the lithium ion in a planar arrangement, namely, the Li ion is located on or very close to the plane defined by the three nitrogen atoms corresponding to nitrate molecules.

[1] http://www.gromacs.org

[2] CP2K, http://www.cp2k.org/

[3] Méndez-Morales, Trinidad and Carrete, Jesús and Cabeza, "scar and Russina, Olga and Triolo, Ales- sandro and Gallego, Luis J. and Varela, Luis M. J. Phys. Chem. B, 2014, 118, 761-770.

[4] Bakó, I. and Hutter, J. and Pálinkás, G. J. Chem. Phys, 2002, 117, 9838-9843.

[5] Bakó, I. and Hutter, J. and Pálinkás, G. J. Phys. Chem. A, 2006, 110, 2188-2194.

[6] Ikeda, T. and B, Mauro, T, Kiyoyuki J. Chem. Phys. 2007, 126, 034501-9.

[7] Ikeda, T. and B, Mauro J. Chem. Phy. 2012, 137, 041101-4.