Structural characterization of single-ion conducting polymer blend electrolytes

Single-ion conducting polymers have become one of the promising electrolyte candidates for next-generation lithium batteries due to their better electrochemical stability and high cation transference numbers. Although there have been previous studies on the ion transport properties of blends of single-ion conducting polymers, their phase behavior and microstructure have not been extensively studied. A novel class of electrolytes, single-ion conducting polymer blend electrolytes (SIPBE), was prepared by blending two distinct classes of polymers, together to generate miscible electrolytes. In this study, we will focus on blends of poly(ethylene oxide) (PEO) with a LiTFSI-containing poly(methyl methacrylate) (PMTFSI-Li). The miscibility was preliminarily characterized using differential scanning calorimetry, wherein only one single glass-transition temperature appearing. The microstructure of the SIPBE was further characterized using small-angle X-ray and neutron scattering techniques to investigate the effect of polymer molecular weights and salt concentrations on phase behavior. The results will help develop a molecular-level understanding of thermodynamics and ion transport mechanism in SIPBE's.