Solid Hybrid Electrolyte Featuring a Vertically Aligned Li_6.4La_3.0Zr_1.4Ta_0.6O₁₂ Membrane for All-Solid-State Lithium Batteries

All-solid-state lithium batteries (ASSLBs) with enhanced safety are considered one of the most promising substitutes for liquid electrolyte-based Li-ion batteries. However, many properties of solid electrolytes, such as ionic conductivity, film formability, and electrochemical, mechanical, thermal, and interfacial stability need to be improved for their practical application. In this study, a vertically aligned Li 6.4 La 3.0 Zr 1.4 Ta 0.6 O 12 (LLZO) membrane with finger-like microvoids was prepared using processes involving phase inversion and sintering. A hybrid electrolyte was then obtained by infusing the LLZO membrane with a solid polymer electrolyte based on poly(ε-caprolactone). The solid hybrid electrolyte (SHE) was a flexible thin film with high ionic conductivity, superior electrochemical stability, high Li + transference number, enhanced thermal stability, and improved Li metal electrode–solid electrolyte interfacial stability. A solid-state Li/LiNi 0.78 Co 0.10 Mn 0.12 O 2 cell assembled with the hybrid electrolyte exhibited good cycling performance, in terms of discharge capacity, cycling stability, and rate capability. Accordingly, the SHE using a vertically aligned LLZO membrane is a promising solid electrolyte for realizing safe, high-performance ASSLBs.