Agglomeration-Free Composite Solid Electrolyte and Enhanced Cathode-Electrolyte Interphase Kinetics for All-Solid-State Lithium Metal Batteries

Polymer composite electrolytes are receiving ever-increasing attention due to the favorable safety and flexibility, while inferior organic/inorganic interphase compatibility inevitably leads to serious agglomeration of ceramic particles and severely blocked Li + transport in bulky electrolytes, especially for “polymer-in-ceramic” (PIC) systems with ultrahigh ceramic content. Herein, a silane coupling agent 3-Isocyanatopropyltriethoxysilane (IPTS) is introduced into PIC electrolyte to build bridge model at organic/inorganic interphase. Via in-situ coupling reaction, conventional weak physical contact between organic/inorganic components has been successfully transformed into stronger chemical interaction, resulting in homogeneous ceramic dispersion, enhanced Li + conductivity (0.6 mS cm -1 at room temperature) and transference number (0.87) with broadened electrochemical window (5.2 V vs. Li + /Li). Moreover, the in-situ built bridge model can also be applied into various cathodes. Notably, the IPTS modified LiCoO 2 (SLCO) and LiNi 0.8 Co 0.15 Al 0.05 O 2 (SNCA) deliver uniform morphology and enhanced Li + apparent diffusion coefficient. In this case, both all-solid-state symmetric and full cells exhibit prolonged cycling life at wide operation temperature. This work provides a universal strategy to optimize the long-ignored tough issues around the interphase for both composite electrolytes and cathodes, also enlightening other composite systems to overcome their intrinsic incompatibility.