Berlin 2018 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 62: Charged Soft Matter, Polyelectrolytes and Ionic Liquids III
CPP 62.3: Vortrag
Donnerstag, 15. März 2018, 10:00–10:15, C 243
Salt and Polymer Dynamics in PPG based Polymer Electrolytes: A 1H and 7Li NMR study — •Manuel Becher, Simon Becker, Lukas Hecht, and Michael Vogel — TU Darmstadt Condensed Matter Physics, Darmstadt, Germany
Facing an increasing need for safe and mechanically stable devices for energy storage, solid-state (lithium)-ion conducting batteries are in the focus of current research. As one of the central components, the electrolyte determines desirable features like high energy density, light weight and high ion conductivity. Polymer electrolytes (salts dissolved in polymers) are already used in portable devices, but suffer from lower electric conductivity as compared to other alternatives. Hence, it is of great interest to enhance the ion diffusivity in the polymer matrix. For this purpose, a fundamental understanding of the transport mechanisms is necessary, but still not available. Here, we focus on amorphous polypropylene glycol (PPG) lithium-salt mixtures, comparing different salts and salt concentrations. We combine several nuclear magnetic resonance (NMR) experiments, namely diffusometry, relaxometry, spectroscopy and exchange studies to ascertain ion and polymer dynamics over a wide range of length and time scales. Selectively investigating cation, anion and polymer host dynamics (7Li, 19F and 1H measurements, respectively) yields a strong correlation between polymer reorientation and ion diffusion. Moreover, we show that the ion transport is strongly affected by a structural inhomogeneity of the mixtures which depends on the solubility of the salts. In this context, we discuss the differences in conductivity of LiClO4 and LiTFSI salts.