A Mechnically Robust Dual-Path Ion-Conductive Biomimetic Interfacial Layer Engineered via Solvation Structure for Ultrastable LATP Solid-State Batteries

The development of Li1.3Al0.3Ti1.7(PO4)3 (LATP) electrolyte is hindered interfacial degradation caused by side reactions with lithium metal anodes. Inspired by the "vein-mesophyll" structure of Cinnamomum camphora leaves, we constructed a mechanically robust dual-path ion-conductive biomimetic interphase (PVLN) via filler alignment and a localized high-concentration electrolyte (LHCE) strategy to stabilize the LATP/Li interface. In the PVLN interlayer, the PVDF-HFP-based LHCE confines DMSO and regulates the local solvent environment, while the well-aligned LATP particles on the PAN substrate provide abundant Li+ coordination and transport sites. This coupled structure decouples ion pairing from ion conduction, facilitates Li+ desolvation and migration, and promotes the formation of continuous Li+ transport pathways. More importantly, neutron powder diffraction analysis elucidated the stable Ti4+ of the PVLN@LATP during cycling, which significantly indicates the PVLN interlayer can reduce the detrimental reduction reactions at the LATP/Li interface, which is rarely reported. As a result, the PVLN@LATP composite exhibits an ionic conductivity of 5.1 × 10-4 S cm-1 and a wide electrochemical stability window of up to 4.85 V. Leveraging these synergistic effects, the Li|PVLN@LATP|Li symmetric cell tested at room temperature achieves stable cycling for over 3000 h, demonstrating excellent interfacial compatibility. This biomimetic composite strategy provides insights and avenues for designing multiphase structures in solid-state batteries.