Regulating PTFE fibrillation via LLZO solid electrolyte incorporation for mechanically robust dry-processed sulfide solid electrolyte membranes

The fabrication of thin and mechanically robust sulfide-based solid electrolyte (SE) membranes remains a key challenge for the practical commercialization of all-solid-state batteries (ASSBs). In particular, the intrinsic ductility of sulfide-based SEs limits effective shear-force transfer to the polytetrafluoroethylene (PTFE) binder during dry processing, thereby suppressing PTFE fibrillation and hindering the formation of a robust fibrous network. Herein, we report an argyrodite-type Li 6 PS 5 Cl (LPSCl)-based SE membrane incorporating Li 7 La 3 Zr 2 O 12 (LLZO) SE particles, to manipulate PTFE fibrillation behavior and simultaneously enhance mechanical robustness and electrochemical performance. The introduction of LLZO particles enhances interparticle interfacial interactions and their friction during dry processing, enabling efficient shear-force transfer to the PTFE binder and promoting the formation of a continuous fibrous network. The enhanced PTFE fibrillation behavior contributes to the formation of a robust and well-integrated interface with both the cathode and the anode. As a result, ASSBs employing the full cell exhibit improved long-term cycling stability, with 81.2% capacity retention after 300 cycles at 0.3C. This work demonstrates the critical role of oxide-based SE additives in regulating fibrillation and microstructural uniformity in sulfide-based SEs, providing an effective strategy for fabricating thin and mechanically robust SE membranes toward their practical implementation in next-generation energy storage systems.