Solid Electrolyte Membrane Prepared from Poly(arylene ether sulfone)- g- Poly(ethylene glycol) for Lithium Secondary Battery

Poly(arylene ether sulfone)-g-poly(ethylene glycol) graft copolymers (PAES-g-PEG) containing 1-butyl-1-methylpyrrollidum bis(fluoromethane sulfonyl) (PYR14-TFSI) were synthesized to prepare the solid electrolyte membranes for lithium secondary battery. Several essential properties including lithium ion conductivity, lithium ion transference number, thermal, mechanical, and dimensional stability were investigated and correlated to the ion cluster dimension examined by small-angle X-ray scattering. The PAES-g-PEG membranes showed the excellent flexibility with the thermal degradation temperature of over 200 °C, the elongation at break of 250%, and the dimensional stability up to 120 °C. As the lithium ion conductivity increased with PYR14-TFSI contents, the membrane with 70 wt % PYR14-TFSI exhibited the highest conductivity of 6.1 × 10^-4 S cm^-1 at room temperature without any mechanical failure. LiCoO₂/SE/Li and S/SE/Li cell assemblies fabricated from this membrane were capable of delivering 126 and 782 mAh g^-1 at a low C-rate, respectively.