Tough and single lithium-ion conductive nanocomposite electrolytes based on PAES--PEG and POSS-PEG for lithium-sulfur batteries

A tough nanocomposite solid electrolyte (CPE) with high lithium (Li) transport capability is fabricated from a self-assembled poly(arylene ether sulfone) (PAES)- g -poly(ethylene glycol) (PEG) matrix and poly(ethylene glycol) functionalized polysilsesquioxane (POSS-PEG) conductive nanofiller. While the tailored CPE possesses facile Li-transporting pathways created by phase-separation between PAES and PEG, Li-ion migrations are even more triggered by Li-selective POSS-PEG and a highly dielectric succinonitrile additive. The CPE exhibits a superior ion conductivity of 2.78 mS cm −1 and Li-transference number of 0.687. Also, this flexible CPE shows a high tensile strength of 3.7 MPa with a Young's modulus of 90.1 MPa and excellent thermal stability up to 220 °C and inflammability due to the presence of the robust PAES matrix reinforced by POSS-PEG. Thanks to the facile Li-transport ability and the effective suppression of Li dendrite growth, the Li-sulfur cell delivers a high discharge capacity of 980.1 mA h g −1 and retains 85.9% of its initial discharge capacity with 98.4% coulombic efficiency after 200 cycles at a 0.2 C-rate. Tough nanocomposite solid electrolytes exhibit facile single Li-ion transport using POSS-PEG and simultaneously achieve both superior conductivity and excellent thermal/mechanical stability via self-assembled PAES- g -PEG for long-term safe LSBs.