Interaction of PEO with LiI/NaI: a density functional approach

The first-principles study of alkali halides dispersed in polyethylene chains is performed, the dispersion of salts modifies the bond lengths of atoms, bending of polymer chains is occurred, and Li/Na cations are found to be attracted towards oxygen anions; it causes to the reduction in crystallinity. Charge density analysis exhibits partially ionic and covalent bonds between C and O atoms of all PEO systems, and ionic bonds between Li and O and between Na and O atoms. There is sp hybridization in all polymer systems; the forbidden energy gap reduces gradually by increasing dispersed salt molecules and is smaller in PEO10–4NaI. The formation of the concentration of Na cations is higher than Li cations in polymer salts. The stability of PEO10–4LiI is larger and that of PEO5–LiI is smaller, and the bond breaking energy is higher in PEO10–4NaI and lower in PEO10–2NaI.