Lewis Acid - Base Interactions in Fe3O4 Nanocomposite PEO Solid Polymer Electrolyte

J.R. Madi Reddy, S.R. Verravalli, V.R. Pendyala (India), and P.P. Chu (Taiwan)

Keywords

Nanocomposite polymer electrolyte; FT-IR; X-raydiffraction, Nanoparticle Fe3O4, Poly (ethylene oxide)(PEO)

Abstract

Fe3O4 nanocomposite of PEO: LiClO4 solid polymer electrolyte films have been prepared by means of solution casting method. FT – IR and X – RD methods have been employed to study structural changes and coordination within this Fe3O4 of PEO: LiClO4 nanocomposite polymer electrolyte. The COC vibrational mode observed in pure PEO around ~ 1100 cm-1 is found to be broadened in its width accompanying shift to higher wave number in nanocomposite of PEO: LiClO4: Fe3O4 electrolyte when compared to Pure PEO, and PEO: LiClO4 films. The two major ClO4 species with different conformations were found in PEO: LiClO4 electrolyte; one being free ClO4 ions with maxima at ~ 623 cm-1 and other ClO4 anion associates with the Li+ cation at ~ 635 cm-1((Li+…ClO4 (i.e., ion-pairing)). The intensity of ion pair formation is found to decrease with increasing of nanosized Fe3O4 composition to PEO: LiClO4. This could be the direct indication of a higher degree of LiClO4 salt dissociation by the addition of nanosized Fe3O4 to PEO: LiClO4 solid polymer electrolyte. Numerous interactions are possible in the nanocomposite PEO electrolyte, where nano Fe3O4 surface has a Lewis acidic group capable of interaction with Lewis base centers of PEO polymer. Thus, this nanosized Fe3O4 oxide may acts as physical cross-linking centers for the PEO chains, and also facilitated salt dissociation, where negatively charged oxygen of Fe3O4 interact with lithium ion.

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