In Situ Constructed “Poly‐Ionic Bridges” Promoting Performances of All‐Solid‐State Lithium‐Sulfur Batteries

ABSTRACT All‐solid‐state lithium‐sulfur batteries (ASSLSBs) suffer from severe polysulfide shuttling and inadequate solid‐solid interfacial contact, which restrict their practical application. Enhancing interfacial ion transport and polysulfide confinement is therefore critical for achieving high energy density and enabling use in electric aviation. Herein, we develop a composite solid‐state electrolyte (DHCSE@PIL) integrating a covalent organic framework (COF) to suppress polysulfide shuttling and a poly(ionic liquid) (PIL) phase to improve interfacial ion transport. In this design, ─SO 3 H‐rich COF functions as functionalized fillers within the Li 6.25 Al 0.25 La 3 Zr 2 O 12 (LALZO)/poly(ethylene oxide) matrix, enabling selective trapping of polysulfides, while in situ polymerization of pyrrolidinium‐based ionic liquids (Pyr 13 TFSI) forms PIL “poly‐ionic bridges” reinforcing electrode‐electrolyte contact. Moreover, pyrrolidinium cations optimize lithium‐salt coordination, facilitating Li + transport and promoting a stable solid electrolyte interphase. Consequently, DHCSE@PIL exhibits an ionic conductivity of 0.74 mS cm −1 and a Li + transference number of 0.65. Li symmetric cells deliver stable plating/stripping for over 8000 h at 3 mA cm −2 , and Li|DHCSE@PIL|S full cells with high sulfur loading achieve 600 stable cycles at 0.5C. Furthermore, an Ah‐level pouch cell delivers an energy density of 482 Wh kg −1 . This synergistic electrolyte/interfacial strategy provides insights into solid‐state electrolyte engineering for advanced ASSLSBs.