Undoing lithium ion association in ionic liquids through the complexation by oligoethers
journal contribution
posted on 2010-12-09, 00:00authored byPaul Bayley, G Lane, L Lyons, D MacFarlane, Maria ForsythMaria Forsyth
Tetraglyme (TG) and the recently developed trimethylsilyl capped analogue (1NM3) when used as additives in a N-methyl-N-propylpyrrolidinium bis(trifluoromethylsulfonyl) amide [C3mpyr][NTf2]/0.65 M LiNTf2 electrolyte have been shown to dramatically enhance the transport properties of this electrolyte. In fact, at a concentration of 20 mol % tetraglyme (leading to a ratio of~1:1 ether molecule per lithium ion), viscosity, conductivity, and the diffusion coefficients of the C3mpyr+ and NTf2− are practically reinstated to the values observed in the absence of lithium, thereby negating the structuring effects of the lithium ion. The 7Li T1 relaxation times also indicate that these additives strongly interact with the lithium ions. Furthermore, although TG has twice the viscosity of 1NM3, the greatest improvement in transport properties was observed for TG.