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Tunable ion transport properties in solid polymer electrolytes for lithium-ion batteries
Date
2025
Authors
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Journal ISSN
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Publisher
University of Delaware
Abstract
Lithium-ion batteries (LiBs) are one of the most widely used energy storage systems; however, the liquid electrolytes in commercial LiBs face safety and performance concerns, including leakage, high flammability, thermal runaway, and lithium dendrite formation that reduces battery efficiency and lifespan. Solid polymer electrolytes (SPEs) are attractive candidates for mitigating the above-mentioned issues, but their slow ion transport significantly hinders practical use. In this dissertation work, three strategies were explored to enhance ion conduction in SPEs. In the first strategy, a blend electrolyte consisting of a single-ion-conducting polymer – poly[lithium sulfonyl(trifluoromethane sulfonyl)imide-methacrylate] (PLiMTFSI) and an ion-conducting polymer – poly(oligo-oxyethylene methyl ether methacrylate) (POEM) was developed. The free volume, generated by PLiMTFSI packing frustration and easily tuned by molecular weight and ion concentration, was leveraged to tailor the ion transport mechanism (segmental-relaxation-dependent vs. hopping motion). The blend electrolyte displayed hopping motion and demonstrated superionic transport with conductivities comparable to a commercialized SPE. In the second strategy, commercially available small-molecule lithium salts were incorporated into the blend system used in the first strategy. The anion chemistry and volume were varied to tune the cation-anion and ion-polymer interaction strengths and the selective cationic transport. Ternary blend electrolyte systems incorporating a bulkier, more delocalized anion facilitated ion hopping by weakening anion–cation and anion–polymer interactions, thereby improving conductivity while maintaining highly selective cation transport. Finally, a lignin-inspired polymer component was blended or copolymerized with POEM. The lignin-inspired polymer effectively restricted the anion motion through anion–dipole and anion–π interactions. In comparison to the phase-mixed copolymer electrolyte, the phase-separated blends exhibited enhanced ion conduction due to the preservation of the POEM-rich domain. Overall, the findings in this dissertation can guide the design of next-generation SPEs in high- performance lithium-ion batteries.
Description
"At the request of the author or degree granting institution, this graduate work is not available to view or purchase until January 05 2027."--Proquest abstract/details page.
Keywords
Lithium-ion batteries, Solid polymer electrolytes, Ion transport mechanism, Energy storage systems