Li$+$ transport in poly(ethylene oxide) based electrolyte: A combined study of neutron scattering, dielectric spectroscopy, and MD simulation

Dynamics of Li$+$ transport in polyethylene oxide (PEO) and lithium bis(trifluoromethanesulfonyl)imde (LiTFSI) mixtures are investigated by combining various experimental techniques (neutron spin-echo and dielectric spectroscopy) with molecular dynamics (MD) simulations. Our results suggest that the characteristic live times within the cages formed by oxygens are mainly determined by the alpha-relaxation which corresponds to local segmental motions of polymers, to a much lesser extent by the main chain relaxation, and not at all by the beta-relaxation or any other faster processes. The significant contribution of Li$+$ hopping process to the ion conductivity is also identified. Subsequently, detailed characteristic length and time scales of various Li$+$ transport processes in solid polymer electrolytes are presented and interpreted.