Electronic structure calculations on lithium battery electrolyte salts

Abstract

New lithium salts for non-aqueous liquid, gel and polymeric electrolytes are crucial due to the limiting role of the electrolyte in modern lithium batteries. The solvation of any lithium salt to form an electrolyte solution ultimately depends on the strength of the cation–solvent vs. the cation–anion interaction. Here, the latter is probed via HF, B3LYP and G3 theory gas-phase calculations for the dissociation reaction: LiX ⇔ Li⁺ + X⁻. Furthermore, a continuum solvation method (C-PCM) has been applied to mimic solvent effects. Anion volumes were also calculated to facilitate a discussion on ion conductivities and cation transport numbers. Judging from the present results, synthesis efforts should target heterocyclic anions with a size of ca. 150 ų molecule⁻¹ to render new highly dissociative lithium salts that result in electrolytes with high cation transport numbers.