(632d) Solid Polymer Electrolyte Networks Via the Active Monomer Mechanism for Lithium Ion Conduction

We report on the synthesis, properties, and ion conductivity of solid polymer electrolytes via an active monomer mechanism that facilitates the reaction of the native hydroxyl and epoxide end-groups of linear polyethers and epoxy molecules, respectively. Their copolymerization is induced via visible light photocuring, which rapidly and cost-effectively produces solid, crosslinked materials. The samples were loaded with different quantities of lithium salts and evaluated by electrochemical impedance spectroscopy (EIS) to determine their ionic conductivity. An increase in lithium salt loading leads to an increase in ionic transport, reaching competitive conductivities of up to 10^-3 S/cm at temperatures typical for battery operation. Analysis reveals the samples are amorphous, with minimal crystallinity, thereby favoring optimal conductivity. Thermal analysis confirms an amorphous structure and the high thermal stability (30-90°). Mechanical analysis shows the materials possess suitable stiffness for applications. The results demonstrate a new synthetic route to tunable crosslinked networks for a broad range of chemical building blocks to achieve high lithium ion conduction and desirable thermal and mechanical properties.