A 3 µm‐Ultrathin Hybrid Electrolyte Membrane with Integrative Architecture for All‐Solid‐State Lithium Metal Batteries

Abstract Ultrathin all‐solid‐state electrolytes with an excellent Li⁺ transport behavior are highly desirable for developing high‐energy‐density solid‐state lithium metal batteries. However, how to balance the electrochemical performance and their mechanical properties remains a huge challenge. Herein, an ultrathin solid electrolyte membrane with a thickness of only 3 µm and a weight of 11.7 g m⁻² is well constructed by integrating individual functionalized organic with inorganic modules. Impressively, the optimized hybrid electrolyte membrane shows a set of merits including a high room‐temperature ionic conductivity of 1.77 × 10⁻⁴ S cm⁻¹, large Li⁺ transference number of 0.65, and strong mechanical strength (strength of 29 MPa, elongation of 95%), as well as negligible thermal shrink at 180 °C. The analysis results reveal that the lithium sulfonate‐functionalized mesoporous silica nanoparticles in the membrane play a crucial role in the selective transport of Li⁺ through anion trapping and cation exchange. The pouch full cell is further assembled with a high‐voltage NCM cathode and thin lithium anode, which exhibits excellent long‐term cycling stability, outstanding rate performance at room temperature, and high safety against abused conditions. The current work provides an innovative strategy for achieving lithium metal batteries with ultrathin all‐solid‐state electrolytes.