A Homogeneous Hexagonal-Structured Polymer Electrolyte Framework for High-Performance Polymer-Based Lithium Batteries Applicable at Room Temperature.

In polymer-based lithium batteries, polymer electrolytes (PEs) exhibit limited ionic conductivity at room temperature (25 °C). To address this issue, this paper describes a hexagonal-structure-based single-ion conducting gel polymer electrolyte (-SICGPE) framework with a robust and efficient cross-linked polymer network, applicable to polymer-based batteries even at 25 °C. The proposed cross-linked polymer network backbone of the -SICGPE, as a semisolid-state thin film type, has the homogeneous honeycomb structure incorporating anion receptor(s) inside each of its hexagonal closed cells and is obtained by cross-linking between trimethylolpropane tris(3-mercaptopropionate) and poly(ethylene glycol) diacrylate in a newly synthesized anion-receptor solution. The excellent structural capability of the -SICGPE incorporating Li/TFSI can enhance ionic conductivity and electrochemical stability by suppressing crystallinity and expanding free volume. Further, the anion receptor in its free volume helps to effectively increase the lithium-ion transference number by immobilizing counter-anions. Experimental results demonstrate dramatically superior performance at 25 °C, such as ionic conductivity (2.46 mS cm), oxidative stability (4.9 V vs. Li/Li), coulombic efficiency (97.65%), and capacity retention (88.3%). These results confirm the developed -SICGPE as a promising polymer electrolyte for high-performance polymer-based lithium batteries operable at 25 °C.