Tailoring Ion Transport Properties of Block Copolymer Electrolytes with End-functionalized Homopolymer Addition

Block copolymer electrolytes based on poly(ethylene oxide) (PEO) have been regarded as promising candidates for solid-state lithium batteries, attributed to the good lithium salt-solvating ability of PEO chains and their high ionic conductivity. However, the inherent crystallinity of PEO is tied to a drastic reduction in ionic conductivity at room temperature, limiting its uses in practically viable batteries. In this study, we report a new means of controlling PEO crystallinity of block copolymers by blending end-group functionalized PEO homopolymers. It has been found that the ionic conductivity and morphology of the resultant blends are related to the type and number of terminal moieties in embedded PEO homopolymers. This result suggests that chain folding of PEO is largely modulated by the end-group-driven intermolecular interactions in PEO phases. It has further shown that ion transport properties of blend electrolytes can be improved by this blend approach.