Relation between structural and conductivity relaxation in PEO and PEO based electrolytes
Artikel i vetenskaplig tidskrift, 2014

The effect of a lithium salt on the general polymer dynamics of poly( ethylene oxide) (PEO) and how these dynamical alterations affect the ionic conductivity and structural relaxations in (PEO)(4):LiClO4 have been investigated. The study was based on differential scanning calorimetry (DSC) and dielectric relaxation studies. The DSC studies indicated an increased glass transition temperature of (PEO)(4):LiClO4 as compared to that of PEO. The polymer-salt complex exhibited enhanced conductivity of sigma(D.C). = 3.2 x 10(-7) S . cm(-1) at room temperature (298 K) due to the presence of mobile Li+ ions. Impedance data have been scaled and analyzed under conductivity and modulus formalisms over wide ranges of frequency and temperature for both PEO and (PEO)(4):LiClO4. For PEO, the analysis of the scaled formalisms indicates that both the conductivity and the structural relaxation mechanisms are temperature-independent above the melting point of PEO. However, below the melting point, the nucleation and growth of spherulites and also the formation of 'interphase' regions in PEO result in a hindered long range D.C. conductivity, which, in turn, leads to a decoupling of the D.C. conductivity and the structural relaxation. However, for (PEO)(4):LiClO4, by comparing the conductivity relaxation data with the calorimetric glass transition and analysis of scaled formalisms, a direct coupling between Li+ ion motions and polymer segmental dynamics is observed for the polymer electrolyte.

Författare

Benson Koch Money

Chalmers, Teknisk fysik, Kondenserade materiens fysik

K. Hariharan

Indian Institute of Technology, Madras

Jan Swenson

Chalmers, Teknisk fysik, Kondenserade materiens fysik

Solid State Ionics

0167-2738 (ISSN)

Vol. 262 785-789

Ämneskategorier

Den kondenserade materiens fysik

DOI

10.1016/j.ssi.2013.09.033