Modulating Ion Transport and Self-Assembly of Polymer Electrolytes via End-Group Chemistry

Abstract

We report a rational design of solid-state dry polymer electrolytes with high conductivity, high mechanical strength, and improved cation transference number. Thiol–ene click chemistry provided orthogonal control over the type and number of end groups in poly(styrene-b-ethylene oxide) (PS-b-PEO) block copolymers. This approach permitted the synthesis of PEO chains with reduced crystallinity, reminiscent of PEO oligomers, thereby playing a key role in improving the room temperature conductivity. Intriguingly, the incorporation of diol or dicarboxylic acid end groups in PS-b-PEO produced a well-defined gyroid structure, leading to order of magnitude improvements in the storage modulus. Out of the various samples examined, the electrolytes bearing terminal diol displayed the highest ionic conductivity and a 2-fold increase in lithium transference number. The improvements in performance are attributed to the reduced interchain aggregation and the anion stabilization mediated by the terminal diol group. The fa...