Self-Sacrificing Interface Engineering for Enhanced Compatibility and Ionic Conduction in LLZTO/Polymer-Based Eutectogel Hybrid Electrolytes

Interfacial instability and low ionic conductivity impede the utilization of PVDF-based electrolytes in solid-state lithium batteries. Herein, a molecular self-sacrificing strategy using bis(catecholato)diboron (B₂cat₂) to stabilize the LLZTO/P(VDF-CTFE) interface was proposed. B₂cat₂ effectively suppresses dehydrofluorination and regulates residual DMF at the molecular level, improving both the bulk phase and interfacial stability. Spectroscopic analyses (UV-vis, XPS, and NMR) confirm strong interactions between B₂cat₂ and LLZTO, leading to enhanced ion transport and lithium interfacial compatibility. The optimized eutectogel hybrid electrolytes (EHEs) achieve high lithium conductivity (0.59 mS cm^-1) and lithium-ion transference number (0.66), long-term cycling (1000 h at 0.3 mA cm^-²), and excellent full-cell performance with LiFePO₄ and NCM811 cathodes. The pouch cell demonstrated remarkable stability across a wide temperature range, retaining a capacity of 79.2% after 150 cycles of charge and discharge at 0.5 C). This work presents an approach for constructing stable interfaces in solid-state batteries.