Influence of the Anion on the Formation of Amorphous Ionically Conducting Lithium Salt Complexes with 18-C-6 and 2.2.2-Cryptand Macrocycles

Abstract

Complexes of lithium salts LiCF3SO3, LiI, LiCH3CO2, LiBF4, LiSCN, and Li[R−NSO2CF3] with the macrocyclic ligands 18-C-6 and 2.2.2-cryptand were examined by differential scanning calorimetry, infrared and Raman spectroscopy, and complex impedance. The formation of an amorphous phase appears to be facilitated by the presence of an unsymmetrical anion containing an ether oxygen of the type [R−NSO2CF3]-. An X-ray crystal structure was determined for Li[CF3SO2N(CH2)2OCH3]; these data and that for the previously reported Li[CF3SO2N(CH2)3OCH3] structure was correlated with the physical properties of their 18-C-6 and 2.2.2-cryptand complexes.

Criteria for solvate ionic liquids

“…The chelate effect is more pronounced for crown ethers having higher K complex values than those of glymes, whereas the melting points of their complexes with Li + ions are frequently higher than those of the corresponding glyme complexes with Li + ions and increase to values above 100 1C. [26][27][28][29] However, a 1 : 1 mixture of 18-crown-6 ether and Li[TFSA] yields a low-melting complex, [Li(18-crown-6) 1 ][TFSA], which melts at approximately 40 1C. 28 Similarly to [Li(G3) 1 ][TFSA] and [Li(G4) 1 ][TFSA], the diffusion coefficients of the Li + ions and the ligand molecules measured using pulsed-field-gradient NMR spectroscopy were identical in the liquid [Li(18-crown-6) 1 ][TFSA]: D Li + = 1.39 Â 10 À8 cm 2 s À1 and D 18-crown-6 = 1.39 Â 10 À8 cm 2 s À1 at 30 1C (supercooled), D Li + = 1.12 Â 10 À7 cm 2 s À1 and D 18-crown-6 = 1.12 Â 10 À7 cm 2 s À1 at 60 1C, respectively.…”

“…[Li(12-crown-4) 1 ][TFSA] and many other complexes of 12-crown-4 ether and Li salts do not melt at temperatures under 100 1C, [26][27][28][29] and so they do not satisfy the definition of an IL. For the same reason, the reported glyme-Li salt complexes, [Li(G3) 1 ]AsF 6 and [Li(G3) 1 ][BPh 4 ], 32 and a number of crown ether-based complexes are not classified as ''solvate ILs'' but as ''solid chelate complexes'' instead at ambient temperatures or as ''molten solvate complexes'' above their melting temperatures even though they satisfy the other criteria in the liquid state.…”

“…À are covalent ones. Mixtures of metal salts and crown-ethers or cryptands are also typical examples of well-defined solvate complex cations, [26][27][28][29] as many of these complexes melt at temperatures much higher than room temperature (usually 4100 1C). The coordinating structures in glyme-Li salt 1 : 1 complexes have also been widely studied as models for poly(ethylene oxide) (PEO)-based polymer electrolytes in crystalline states [30][31][32][33][34] and using ab initio calculations.…”

Poly[bis(acetonitrile-κN)bis[μ3-bis(trifluoromethanesulfonyl)imido-κ4O,O′:O′′:O′′′]dilithium]

“…For a related structure of LiN(SO 2 CF 3 ) 2 , see: Henderson et al (2005); Davidson et al (2003); Brouillette et al (2002); Dillon et al (2001). For the structure of CH 3 CN with lithium salts, see: Klapö tke et al (2006); Brooks et al (2002); Yokota et al (1999); Raston et al (1989).…”

I?3/I? Redox Behavior of Alkali-metal Iodide Complexes with Crown Ether/Cryptand Macrocycles and Their Applications to Dye-sensitized Solar Cells

“…Although there are some researches on electrolytes containing macrocyclic ligands 14,15 used in other kinds of batteries, the employment of alkali-metal iodide complexes with crown ether and cryptand macrocycles in DSC has not been reported yet.…”