POLYMER ELECTROLYTES - STRUCTURE AND ELECTRODE PROCESSES

Citation
Pg. Bruce et al., POLYMER ELECTROLYTES - STRUCTURE AND ELECTRODE PROCESSES, Solid state ionics, 78(3-4), 1995, pp. 191-198
Citations number
23
Categorie Soggetti
Physics, Condensed Matter","Chemistry Physical
Journal title
ISSN journal
01672738
Volume
78
Issue
3-4
Year of publication
1995
Pages
191 - 198
Database
ISI
SICI code
0167-2738(1995)78:3-4<191:PE-SAE>2.0.ZU;2-M
Abstract
Two frequently neglected topics in the field of polymer electrolytes a re discussed, namely the structure of crystalline polymer:salt complex es and the redox electrochemistry at the metal electrode/polymer elect rolyte interface. The crystal structure of the PEO(3):LiCF3SO3 complex has been obtained from powder X-ray data. The PEO chains adopt a heli cal conformation with Li+ ions located in each turn of the helix and c oordinated by three ether oxygens plus one oxygen from each of two CF3 SO3- anions completing a trigonal bipyramidal coordination around the Lif ion. Each CF3SO3- anion bridges two adjacent Li+ ions along the ch ain, the -CF3 groups project into the interchain space. The polymer el ectrolyte may be regarded as an infinitely extended columnar coordinat ion complex with no ionic crosslinking between the helical columns. Cy clic voltammetry and ac impedance measurements have been carried out o n the Eu-3+/2+ couple in PEO at 80 degrees C. The voltammetric results are consistent with an EC mechanism, involving reduction of Eu3+ to E u2+ followed by a chemical step in which Eu2+ is consumed. Both electr on transfer and Eu3+ diffusion appear to be slow. Ac impedance suggest s that D-Eu3+ is approximately 4 X 10(-16) cm(2) s(-1).