Tuning Ion and Polymer Dynamics of Single-Ion Polymer Electrolytes by Crystalline Plasticizers or Cross-linking Nanoparticles

Dielectric relaxation spectroscopy (DRS) and oscillatory shear are used to investigate ion dynamics of a series of poly(lithium acrylate) (PLiA)-based single-Li⁺ conducting polymer electrolytes, where PLiA is either copolymerized with poly(ethylene glycol) methyl ether methacrylate in N-methylacetamide for non-aqueous polymer electrolytes or cross-linked with vinyl silica nanoparticles in water for aqueous polymer electrolytes. To deduce the mechanism of ion transport in these single-ion conducting gel polymer electrolytes (SGPEs), the Macdonald and Onsager models are used to separately determine the number density of conducting ions and their mobility and to understand mobile isolated dipole motions, from analysis of electrode polarization and dielectric constant in DRS. The electrochemical performance is also explored in the SGPE assembled with electrodes, as supercapacitors or lithium-metal batteries. These fundamental results can provide insights into the design of fast Li⁺ conducting solid-state polymer electrolytes for energy storage devices.