Preparing Two‐Dimensional Ordered Li0.33La0.557TiO3 Crystal in Interlayer Channel of Thin Laminar Inorganic Solid‐State Electrolyte towards Ultrafast Li+ Transfer

Inorganic superionic conductor holds great promise for high-performance all-solid-state lithium batteries. However, the ionic conductivity of traditional inorganic solid electrolytes (ISEs) is always unsatisfactory owing to the grain boundary resistance and large thickness. Here, a 13 μm-thick laminar framework with ≈1.3 nm interlayer channels is fabricated by self-assembling rigid, hydrophilic vermiculite (Vr) nanosheets. Then, Li_0.33 La_0.557 TiO₃ (LLTO) precursors are impregnated in interlayer channels and afterwards in situ sintered to large-size, oriented, and defect-free LLTO crystal. We demonstrate that the confinement effect permits ordered arrangement of LLTO crystal along the c-axis (the fastest Li⁺ transfer direction), permitting the resultant 15 μm-thick Vr-LLTO electrolyte an ionic conductivity of 8.22×10^-5 S cm^-1 and conductance of 87.2 mS at 30 °C. These values are several times' higher than that of traditional LLTO-based electrolytes. Moreover, Vr-LLTO electrolyte has a compressive modulus of 1.24 GPa. Excellent cycling performance is demonstrated with all-solid-state Li/LiFePO₄ battery.