Lithium transport in a macrocyclic electrolyte

We have carried out nuclear magnetic resonance (NMR) studies on a new class of electrolyte consisting of a lithium salt (LiMPSA) and a macrocycle ([2.2.2] cryptand). NMR diffusion coefficient measurements have determined the motion of lithium cations (formula presented) polyatomic anions (MPSA) (formula presented) and encapsulating macrocycles (formula presented) with the striking result that they are equal over a large temperature range. Diffusion coefficients as low as (formula presented) (formula presented) have been measured through the use of a 42 T/m fringe-field gradient. The magnitudes of the anion and cryptand diffusion were found to be consistent with a free-volume picture for translational diffusion. The transport of the lithium cations was interpreted as taking place mainly through association with large anions (MPSA) and encapsulating macrocycles ([2.2.2] cryptand), with averaged residence time fractions of 77 and 23 %, respectively. NMR spin-lattice relaxation time measurements of (formula presented) and (formula presented) spins have also been performed.