Highly Stable Solid Hybrid Electrolytes Based on Li-Ion Conductive Li_6.4La₃Zr_1.4Ta_0.6O₁₂ Framework for All-Solid-State Lithium Batteries with High Energy Density and Long Cycle Life

All-solid-state lithium batteries (ASSLBs) are one of the best candidates for improving energy density and enhancing battery safety. However, many properties such as ionic conductivity, electrochemical and mechanical stability need to be improved for practical application. In this work, a vertically aligned Li_6.4La₃Zr_1.4Ta_0.6O₁₂ (LLZO) framework composed by three different layers (dense layer, vertical aligned layer and finger liked layer) was prepared by phase inversion method. A framework-based solid hybrid electrolyte (F-SHE) was then obtained by penetrating poly(ε-caprolactone) (PCL)-based polymer electrolyte into LLZO framework. The resulting flexible F-SHE exhibited a high ion conductivity of 1.03×10^-4 S cm^-1 at 25 °C, which was attributed to the vertical aligned lithium-ion conductive LLZO framework that provided fast conduction pathway for lithium ions. The lithium symmetric cells assembled with F-SHE showed a long cycling life more than 700 h at 0.3 mA cm^-2, indicating the solid electrolyte promoted a uniform flux for lithium stripping/plating and suppressed the growth of lithium dendrite. The solid-state Li/NCM cell employing F-SHE exhibited good cycling performance in terms of discharge capacity and cycling stability. Our results demonstrate that the F-SHE can be a promising electrolyte for practical application in ASSLBs with enhanced safety and long cycle life.