Poly(butylene terephthalate)-b-poly(ethylene oxide) alternating multiblock copolymers: Synthesis and application in solid polymer electrolytes

Abstract

We presented here the synthesis of poly(butylene terephthalate) (PBT) and poly(ethylene oxide) (PEO) alternating multiblock copolymers (mBCPs), (PBT-b-PEO-b-PBT)n, via a novel cascade polycondensation-coupling ring-opening polymerization (PROP) method. The chemical structure of (PBT-b-PEO-b-PBT)n mBCPs was revealed by 1D and 2D NMR techniques. By blending with lithium bis(trifluoromethane)sulfonamide (up to r ≡ [Li+]/[EO] of 0.20), the mBCP-based solid polymer electrolytes (SPEs) show excellent performance in all-solid-state lithium batteries. Impedance spectroscopy showed that a maximum ionic conductivity, ∼8.2 × 10−4 S/cm at 90 °C, was achieved at r = 0.10 for the mBCP (76 wt.% PEO) SPEs. A high Cd (charge passed through the symmetric cell before short-circuit) of 441 C/cm2 was achieved at the current density of 0.3 mA/cm2 at 90 °C. Because of the facile synthesis, the rich molecular architecture of mBCP, and the high melting point of PBT, these new mBCP SPEs provide a new platform for SPE design.