Engineering a semi-immobilized ionic liquid interface layer to boost Li+ conduction at organic-inorganic interface

Composite solid-state electrolytes have attracted growing attention due to their good flexibility and wide range of interfaces. However, the inherent poor compatibility at the organic–inorganic interface significantly impedes lithium-ion transport, limiting overall electrochemical performance. In this study, a continuous semi-immobilized ionic liquid interface layer (SIL) was constructed on the surface of three-dimensional Li 6.4 La 3 Zr 2 Al 0.2 O 12 (3D-LLZAO). The SIL facilitates Li + adsorption through the pre-exchanged TFSI - anion with Cl - ions in the ionic liquid within the SIL and promotes rapid hops migration of Li + among anionic sites. In addition, the introduced TFSI - anions reduce the interaction between poly(ethylene oxide) (PEO) chains and Li + , thus enhancing ion mobility. Moreover, the SIL effectively regulates the concentration gradient of Li at the electrolyte/anode interface, ensuring uniform Li + nucleation and deposition. As a result, the prepared 10LIP electrolyte exhibits a simulated Li + diffusion coefficient 5.16 times higher than that of the 10LP electrolyte, alongside an ionic conductivity reaching 6.98 × 10 −4 S cm −1 . This work proposes a rational strategy for enhancing interfacial ion transport in composite solid electrolytes via the introduction of a semi-immobilized ionic liquid interface layer at the organic–inorganic interface, offering valuable insights for the lithium-ion transport at organic–inorganic interface.