Ion pair dissociation effects of aza-based anion receptors on lithium salts in polymer electrolytes

摘要

The addition of aza-based anion receptors greatly increases the conductivity of polymer electrolytes based on LiCl and KI complexes with poly(ethylene oxide) (PEO). In some cases the conductivity increase is more than two orders of magnitude. Also the addition of the anion acceptors imparts a rubber like consistency to the normally stiff PEO salt films. Ion-ion, ion-polymer and anion-complex interactions were studied using Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy at the K and Cl K edges and at the I L(sub I) edge. The NEXAFS results show that Cl(sup (minus)) and I(sup (minus)) anions are complexed with the nitrogen groups of the anion receptors. The degree of complexation is related the chain length of the complexing agent and the number of R(double bond)CF(sub 3)SO(sub 2) groups that are used to substitute for the amine hydrogen atoms in these aza-ether compounds. NEXAFS spectra at potassium K edge provide supplemental evidence for the ion pair dissociation effects of the anion receptors. The results show that dissociated K(sup +) cations are complexed with oxygen atoms of the PEO chains.