Surface-functionalized Li_1.3Al_0.3Ti_1.7(PO₄)₃ with synergetic silane coupling agent and ionic liquid modification for PEO-based all-solid-state lithium metal batteries

Surface functionalization is one effective strategy for optimizing the stability of Li_1.3Al_0.3Ti_1.7(PO₄)₃ (LATP) with Li metal anodes and the compatibility between the components of an electrolyte for lithium battery. Herein, a bifunctional modification layer induced by the silane coupling agent (SCA) and ionic liquid (IL) are successfully introduced onto the surface of LATP particles (defined as LATP@SCA-0.25IL) through chemical grafting and ion exchange strategies. Benefitting from the synergistic effect between the protection of modification layer and the effectively reduced interaction of PEO chain segments with Li⁺, the compatibility of LATP with the Li metal anode is improved, and the dispersion of LATP in PEO matrix is enhanced, a faster Li⁺ transfer is thereby enabled. As a result, thus-prepared LATP@SCA-0.25IL composite polymer electrolyte (CPE) shows an excellent electrochemical property with high ionic conductivity (1.455 × 10⁻³ S cm⁻¹ at 60 °C), enhanced Li-ion transference number (0.40), wide electrochemical stability window (4.76 V vs. Li⁺/Li) and favorable Li metal compatibility (over 1200 h). Furthermore, separately assembled Li/LATP@SCA-0.25IL CPE/LFP coin full cells and pouch cells verify the operational feasibility under extreme conditions. This work paves a new way to protect LATP and promote its practical application in all-solid-state lithium batteries.