(383a) A Neutron Scattering Study of Ion-Conduction Mechanisms in Nanocomposite Polymer Electrolytes

Polymer Electrolytes are the key to light-weight and energy-dense lithium ion batteries but suffer from low room temperature ion conductivities. Spherical ceramic fillers are known to improve ion conductivity and mechanical properties but are still orders of magnitude away from commercialization. Understanding the ion conduction mechanism enables better design of the electrolyte system. Two important factors that govern ion conduction include electrolyte microstructure and polymer dynamics. While electron microscopy and small angle neutron scattering (SANS) provide structural information, quasi-elastic neutron scattering (QENS) examines polymer dynamics. QENS probes two processes: segmental dynamics of polymer chains and rotation of highly-conductive crystalline channels. While the former process remains unaffected by presence of particles, the latter becomes more restricted. Based on this information, polymer electrolytes were designed with high aspect ratio fillers to enable further stabilization of the highly conducting channels. This results in one-order of magnitude improvement in lithium ion-conduction over spherical fillers.