Engineered Interfaces in Hybrid Ceramic–Polymer Electrolytes for Use in All-Solid-State Li Batteries

Composites of inorganic lithium ion conducting glass ceramics (LICGCs) and organic polymers may provide the best combination of properties for safe solid separators in lithium or lithium ion batteries to replace the currently used volatile liquid electrolytes. A key problem for their use is the high interfacial resistance that develops between the two, increasing the total cell impedance. Here we show that the application of a thin conformal SiO₂ coating onto a LICGC followed by silanization with (CH₃CH₂O)₃–Si–(OCH₂CH₂)–OCH₃ in the presence of LiTFSI results in good adhesion between the SiO₂ and the LICGC, a low resistance interface, and good wetting of Li⁰. Further, the cross-linked polymer formed on the surface of the silanated SiO₂ interface formed from excess (CH₃CH₂O)₃–Si–(OCH₂CH₂)–OCH₃ prevents corrosion of the LICGC by Li⁰ metal. The use of SiO₂ as a “glue” enables compatibilization of inorganic ceramics with other polymers and introduction of interfacial pendant anions