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Identifier

000434035

Title

Effect of molecular weight and star shaped architecture on conductivity of poly(ethylene oxide) electrolytes

Alternative Title

Επίδραση μοριακού βάρους και αστεροειδούς αρχιτεκτονικής στην αγωγιμότητα ηλεκτρολυτών πολυ(αιθυλενοξειδίου)

Author

Χατζογιαννάκης, Δημήτριος Γ.

Thesis advisor

Ανασταστιάδης, Σπύρος
Γλυνός, Εμμανουήλ

Reviewer

Σακελλαρίου, Γεώργιος
Χαρμανδάρης, Ευάγγελος

Abstract

Throughout this MSc Thesis, we try to understand the effect of linear poly (ethylene oxide), PEO, molecular weight (M_w) and star-shaped macromolecular architecture on the thermal and electrical properties of polymer electrolytes. The starting point of this work is the design, the fabrication and the evaluation/optimization of a custom-, home-made environmental chamber for the measurement of ion-conductivity of the polymer electrolytes under consideration in controlled atmosphere and temperature. Several different electrolytes were prepared having different molar ratios of the lithium salt, r = [Li⁺]/[EO]. To gain insight on the effects PEO macromolecular characteristics on the structure-property relationship of polymer electrolytes, the ion conductivity measurements were combined with differential scanning calorimetry, Raman spectroscopy, and rheology. In the case of linear PEO polymer electrolytes, the ion-conductivity was shown to decrease with molecular weight, reaching a plateau for M_w larger than around 2 kg/mol. Notably, star-shaped PEO with larger number of arms based electrolytes showed five orders of magnitude increase in their mechanical properties (zero shear viscosity) while the ion-conductivity was less than an order of magnitude lower than the corresponding linear electrolytes. Because the design of mechanical robust electrolytes with superior ion conductivity at room temperature has been the subject of research for other energy-related applications, like anion exchange membranes for fuel cells, or efficient active layers in dye-sensitized solar cells, we believe our findings are of great interest to the corresponding scientific community.

Language

English

Subject

Crystallization

Ionic conductivity

Lithium batteries

Poly(ethyleneoxide)

Solid polymer electrolytes

Ιοντική αγωγιμότητα

Κρυσταλλικότητα

Μπαταρίες λιθίου

Πολυ(αιθυλενοξείδιο)