(266d) Molecular-Level Redesign of Solid Polymer Electrolytes to Enable High Ion Conductivity and Electrochemical Stability

Advancement in energy dense, yet safe batteries is essential for several applications including portable electronics and transportation. However, a major challenge in energy storage systems is the instability of electrolyte materials due to their limited chemical and electrochemical stability, as well as their flammability. We believe, solid-state polymer electrolytes can address the inherent problems of their liquid counterparts and simultaneously provide new avenues for battery development with unprecedented mechanical design. In this regard, polyether-based polymers have been the most widely studied solid electrolyte because of their ability of solvating metal salts for ion transport. However, conductivity of polyethers is highly temperature dependent because of their crystallinity and they have limited electrochemical stability due to the ease of electron extraction at high voltages (>3.8V vs Li/Li⁺). In this talk, I will discuss our recent work of redesigning monomer chemistry of ion conducting polymers by ab-initio calculations. Based on the theoretical predictions, we synthesized a new class of polymer electrolytes and evaluated their ion transport and rheological properties. We further utilized nuclear magnetic resonance (NMR), infrared spectroscopy (FTIR) coupled with molecular dynamics (MD) simulations to understand the solvation structure and ionic aggregations. Finally, we demonstrate the application of these rationally designed polymer electrolytes in a high-voltage lithium metal battery, under specific conditions where conventional polyether-based electrolytes fail to operate.