| Increasing global energy demand is driving the development of renewable electrical energy sources such as solar and wind power. The implementation of these renewable yet intermittent energy sources necessitates advances in electrical energy storage for both stationary and portable consumption. While electrochemical devices such as fuel cells and lithium ion batteries will likely play a large role in these endeavors, their reliability hinges crucially on improving their constituent electrolyte materials. Polymeric single-ion conductors (PSICs), in which one ion is immobilized on a polymeric scaffold with a mobile charge-balancing counterion, have garnered substantial attention as high performance electrolytes. In this thesis, we describe our efforts to synthesize and to understand the fundamental structure-property relationships that govern ion transport in next generation PSICS. Through the modular synthesis and physical characterization of two series of poly(4-vinylbenzyl(alkyl)imidazolium) polymerized ionic liquid (POIL) homopolymers, we observe two different conduction mechanisms for solvated versus solvent-free polymers. Whereas ion transport in solvent-free polymers depends sensitively on polymer segmental dynamics, solvated polymers exhibit ion transport mediated by the solvent. We extend these studies to microphase separated POIL block copolymers to investigate the effects of nanoscale morphology on ionic conductivity. We find that morphological defects in copolymers that form cylindrical ion-conducting channels in an insulating matrix suffer from poor conductivities. The second part of this thesis focuses on lithium PSICs as new electrolytes for lithium ion batteries. We demonstrate the efficient and scalable synthesis of a lithium bis(malonato)borate-containing monomer and polymerize it by acyclic diene metathesis. This polymer exhibits high lithium conductivity in propylene carbonate, and it oxidizes to form a robust solid-electrolyte interphase with a wide electrochemical stability window. Finally, we describe the thiol-ene crosslinking polymerization syntheses of a series of lithium single-ion conducting network gels, as next-generation lithium ion battery electrolyte candidates. Using this polymeric platform, we study the effects of crosslink density on the mechanical attributes and the ionic conductivities of these hybrid separator/electrolytes. |
