Lithium-Salt-Containing Ionic Liquid-Incorporated Li–Al-Layered Double Hydroxide-Based Solid Electrolyte with High-Performance and Safety in Solid-State Lithium Batteries

Solid-state lithium batteries are highly promising for energy storage applications because of their high energy density and good safety. Herein, a novel solid electrolyte based on ionic-liquid-impregnated Li–Al layered double hydroxides (Li–IL@Li–Al LDH) is reported. Since the Li⁺ ions can be inserted into the vacant octahedral sites of the Li–Al LDH and the related anions intercalated into the interlayer for the charge balance, which can facilitate the transport of Li⁺ ions and avoid the interference of anions, the Li–IL@Li–Al LDH solid electrolyte with the optimized Li–IL/Li–Al LDH wight ratio of 2:1 exhibits a high ionic conductivity of 1.04 × 10^–3 S·cm^–1 with a Li⁺ transfer number of 0.35 at 40 °C. Moreover, this solid electrolyte demonstrates excellent nonflammability, good lithium stability, high electrochemical stability, and low interface resistance with electrodes. The fabricated LiFePO₄/Li–IL@Li–Al LDH (2.0:1)/Li battery displays outstanding cyclability and rate capability at 40 °C, indicating that the Li–IL@Li–Al LDH SE should have great potential for applications in the solid-state lithium batteries.