Styrenic BAB Triblock Copolymers Functionalized with Lithium (N-Tetrafluorophenyl)trifluoromethanesulfonamide as Solid Single-Ion Conducting Electrolytes

Abstract

Solid single-ion conducting electrolytes based on well-defined block copolymers show great potential for use in lithium batteries. Here, we report on triblock copolymers with an ion-conductive poly(ethylene oxide) (PEO) center block and two flanking blocks of poly(lithium 2,3,5,6-tetrafluorostyrene-4-trifluoromethanesulfonamide). The copolymers were prepared through atom transfer radical polymerization (ATRP) of pentafluorostyrene using a bidirectional PEO macroinitiator, followed by quantitative nucleophilic aromatic substitution of p-fluorine atoms with sodium trifluoromethanesulfonamide. The ionic content of the copolymers was readily regulated by controlling the monomer feed ratio in the ATRP to obtain [EO]/[Li] between 4 and 88, and thermal decomposition occurred only above ∼300 °C, which indicates a high thermal stability. Above the melting point of the PEO center block, a copolymer containing 16 wt % of the flanking blocks ([EO]/[Li] = 40) reached a conductivity of 5.7·10-6 S cm-1 at 70 °C. The overall results indicate that well-designed polymers functionalized with lithium (N-perfluorophenyl)trifluoromethanesulfonamide groups show potential as solid single-ion conducting electrolytes.