Influence Of Confinement On Polymer-Electrolyte Relaxational Dynamics
- PDF / 168,350 Bytes
- 10 Pages / 612 x 792 pts (letter) Page_size
- 29 Downloads / 201 Views
P9.2.1
INFLUENCE OF CONFINEMENT ON POLYMER-ELECTROLYTE RELAXATIONAL DYNAMICS J.-M. Zanotti1,2, L.J. Smith3, D.L. Price 4,2 and M.-L. Saboungi 5 1
Laboratoire Léon Brillouin (CEA-CNRS), CEA Saclay, 91191 Gif/Yvette cedex, France Intense Pulsed Neutron Source, Argonne Nat. Lab., Argonne, IL 60439, USA 3 Clark University, 950 Main Street Worcester, MA 01610, USA 4 CRMHT (CNRS), Avenue de la Recherche Scientifique, 45071 Orléans, France 5 CRMD(CNRS), Avenue de la Recherche Scientifique, 45071 Orléans, France 2
ABSTRACT Conception and industrial production of viable high specific energy/power batteries is a central issue for the development of non-polluting vehicles. In terms of stored energy and safety, solid-state devices using polymer electrolytes are highly desirable. One of the most studied systems is PEO (polyethylene oxide) complexed by Li salts. Polymer segmental motions and ionic conductivity are closely related. Bulk PEO is actually a biphasic system where an amorphous and a crystalline state (Tg ≈ 213 K, Tm ≈ 335 K) coexist. To improve ionic conduction in those systems requires a significant increase of the amorphous phase fraction where lithium conduction is known to mainly take place. Confinement strongly affects properties of condensed matter and in particular the collective phenomena inducing crystallization. Confinement of the polymer matrix is therefore a possible alternative route to the impractical use of high temperature. Results of a quasi-elastic incoherent neutron scattering study of the influence of confinement on polyethylene oxide (PEO) and (PEO)8Li+[(CF3SO2)2N]- (or (POE)8LiTFSI) dynamics are presented. The nano-confining media is Vycor, a silica based hydrophilic porous glass (characteristic size of the 3D pore network ≈ 50 Å). As expected, the presence of Li salt slows down the bulk polymer dynamics. The confinement also affects dramatically the apparent mean-square displacement of the polymer. Local relaxational PEO dynamics is described KWW model. We also present an alternate model and show how the detailed polymer dynamics (correlation times and local geometry of the motions) can be described without the use of such stretched exponentials so as to access a rheology-related meaningful physical quantity: the monomeric friction coefficient.
INTRODUCTION Up to date many studies have shown the interest and the feasibility of hybrid battery [1] cells where organic and inorganic components are used. One of the most studied systems is PEO (polyethylene oxide) complexed by Li salts. Bulk PEO is actually a biphasic system where an amorphous and a crystalline state (Tg ≈ 213 K, Tm ≈ 335 K) coexist. Confinement is known to strongly affect properties of condensed mater and in particular the collective phenomena inducing crystallization [2]. A possible alternative solution to this high temperature mode is the confinement of the polymer matrice.
P9.2.2
Structure of polymer chains confined in Vycor porous glass [3,4] have already been reported [5] and found in agreement with theoretical predictions
Data Loading...
