Segmental dynamics in PEO-based polymer electrolytes doped with ionic liquid

This study investigates model electrolytes based on a short chain block copolymer of poly(ethylene oxide)-polyethylene (PEO-PE) doped with ionic liquids (ILs), focusing on the influence of mono- and divalent cations on polymer chain relaxation. Movement of ions as charge carrying components in the system is tied with the polymer chain dynamic. Using quasi-elastic neutron scattering (QENS), the governing diffusion mechanism of hydrogen atoms can be used to investigate segmental relaxation. Jump diffusion better explains the dynamics in the PEO-PE block copolymer, while pure PEO segmental relaxation follows Fickian diffusion. Also, PE block segmental motion tends to be Fickian in all conditions. The results suggest that IL or salts can slow PEO-PE hops and make IL appear more Fickian. Most fitted diffusion coefficients for hydrogen atom in samples fall in the 10⁻¹⁰ m²·s⁻¹ range, which is consistent across systems, that is inline with findings in the literature.