Local li coordination and ionic transport in methacrylate-based gel polymer electrolytes

Voigt N., Isken P., Lex-Balducci A., Van Wullen L.

Abstract

The local Li cation coordination motifs and the interactions between the hosting methacrylate-based polymer membrane and the liquid electrolyte [1 M LiPF6 in ethylene carbonate (EC)/dimethyl carbonate (DMC)] are studied by employing liquid and solid-state NMR spectroscopy. At low temperatures, two different coordination modes for Li cations are identified with the help of dipolar-based solid-state NMR techniques, one of which is the exclusive coordination by DMC molecules, while the other is a co-coordination by the polymer and DMC molecules. At room temperature, Li cations are found to be extremely mobile, coordinated by EC and DMC molecules as well as the copolymer, as found by liquid-state NMR spectroscopy. Li coordination in GPE: In gel polymer electrolytes (GPE), the interactions between the various constituents - polymer, electrolyte and Li solvent - delicately control the material's key performance, the Li ion conductivity. For an optimization of the material's performance, an extended understanding of these interactions is necessary. In this work, these are studied employing liquid and solid state NMR spectroscopy. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.