FACTORS AFFECTING X-RAY ABSORPTION FINE-STRUCTURE OF ZINC IN OXYGEN-PLUS-HALIDE ENVIRONMENTS WITHIN POLYMER ELECTROLYTES

The general features of polymer electrolytes formed from polymer/salt systems suitable for EXAFS studies are discussed. Complications arisin g from mixed morphology and the use of different drying procedures are addressed. The difficulties of detecting local structure contribution s from the polymer chains in the presence of powerful anion and/or cat ion backscatterers are considered. Results are presented for bromine K -edge EXAFS spectra of PEO(n):ZnBr2 (n = 4, 8) for samples subjected t o three different drying regimes. Comparison of these results with pre vious studies of cation local structure strongly indicates the presenc e of ZnBr2 entities that interact only modestly with the surrounding p olymer, in contrast to the observed behavior for nickel and other diva lent polymer electrolytes. Further results for bromine local structure in the amorphous regions (i) between salt-containing spherulites, and (ii) within a large spherulite in the intergranular zones of PEO4:ZnB r2 show no difference in the EXAFS contribution from zine nearest neig hbors and a detectable small change in Br-O distance.