Dynamic Ion-Pair Networks Enable Selective Li+ Transport for Stable and Efficient Solid-State Lithium-Sulfur Batteries.

Solid-state lithium-sulfur (Li-S) batteries are intrinsically constrained by persistent Li+-anion coordination in polymer electrolytes, which couples Li+ migration to anion motion and limits both interfacial stability and sulfur redox kinetics. Here, we show that incorporating an ionic liquid modified ZIF-67 (IL@ZIF-67) into a polymer solid electrolyte enables deliberate reorganization of ion coordination and reconfiguration of Li+ transport pathways at the molecular level. ZIF-67 sites preferentially anchor TFSI-, while confined ionic liquid domains reshape Li+ coordination, establishing a dynamic ion-pair network with weakened Li+-anion coupling and spatially restricted anions. This coordination reorganization decouples long-range Li+ transport from anion migration, lowers the Li+ migration energy barrier, and homogenizes Li+ flux across the electrolyte. Consequently, a stable LiF/Li2S-rich solid electrolyte interphase forms at the lithium metal interface, while continuous Li+ supply mitigates solid-solid interfacial polarization and accelerates reversible S─C/S─S bond conversion and Li2S nucleation/decomposition kinetics in SPAN cathodes. As a result, the solid-state Li-S batteries deliver a high reversible capacity of 1004.97 mAh g-1 after 150 cycles at 0.2 C, prolonged cycling stability over 500 cycles at 1 C with a decay rate of ∼0.06% per cycle, highlighting ion-pair regulation via ionic-liquid-engineered MOF fillers as an effective pathway toward high-performance solid-state Li-S batteries.