Solvent-Free Approach for Interweaving Freestanding and Ultrathin Inorganic Solid Electrolyte Membranes

Abstract

All-solid-state batteries (ASSBs) have gained considerable attention due to their inherent safety and high energy density. However, fabricating ultrathin and freestanding solid electrolyte membranes for practical all-solid-state pouch cells remains challenging. In this work, polytetrafluoroethylene (PTFE) fibrilization was utilized to interweave inorganic solid electrolytes (SEs) into freestanding membranes. Representative SE membranes, including Li6PS5Cl, Li3InCl6, and Li6.5La3Zr1.5Ta0.5O12, demonstrate not only a thickness of 15–20 μm but also high room-temperature ionic conductivity (>1 mS cm–1). All-solid-state pouch cells with bilayer Li6PS5Cl and Li3InCl6 membranes deliver a high capacity of 124.3 mAh g–1 at 0.1 C and an initial Coulombic efficiency of 89.4%. Furthermore, using a 20 μm LLZTO membrane as a ceramic separator, a solid-state pouch cell with a high-capacity LiNi0.8Mn0.1Co0.1O2 electrode (>3 mAh cm–2) displays both exceptional cycling stability and unprecedented safety. We believe that this solvent-free technology would be a feasible and cost-effective means of transferring ASSB technology from the laboratory to the factory.