Surface-functionalized Li1.3Al0.3Ti1.7(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 Li1.3Al0.3Ti1.7(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 x 10-3 S cm -1 at 60 degrees 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.