Structural and dynamical properties of polymer electrolytes PPO-LiClO4

The structure and dynamics of a prototype of polymer electrolytes, PPO-LiClO4, have been investigated using neutron diffraction and quasi-elastic neutron scattering (QENS). The aim is to gain insights into microscopic structures and processes that may be of importance for the ionic conductivity mechanism. The diffraction experiments reveal large structural changes on an intermediate length scale, 4-10 Angstrom, as the polymer is doped with salt. The effects may partly be explained by local segmental ordering of the polymer ether-oxygens around the solvated cations. The QENS results indicate that the segmental motions, which have been discussed to be of vital importance for the ionic mobility, slow down considerably when coordinated to cations. The results are discussed in relation to proposed models for the structure and the conductivity mechanism.