Recent progress in silane coupling agents for high-energy-density all-solid-state lithium batteries

Replacing flammable liquid electrolytes with solid electrolytes provides a promising pathway toward safer lithium batteries with high-voltage cathodes and high-capacity anodes. However, they show interfacial issues, including poor solid-solid contact, high interfacial resistance, detrimental interfacial reactions, and lithium dendrite growth. Silane coupling agents have been used as molecular interfacial modifiers to address these challenges. Their bifunctional structure consists of hydrolyzable -Si(OR)₃ groups that can form strong bonds with inorganic surfaces, as well as tunable organic groups that can interact with polymers, lithium salts, active materials, or conductive networks. This molecular bridging effect allows silane coupling agents to enhance interfacial adhesion, regulate surface chemistry, improve phase compatibility, suppress parasitic reactions, and promote homogeneous lithium-ion transport across electrode/electrolyte interfaces. This review summarizes recent advances in the use of silane coupling agents in high-energy-density all-solid-state lithium batteries (ASSLBs) and focuses on molecular design, bonding chemistry, interfacial regulation mechanisms, and structure-performance relationships. A short conclusion and outlook regarding current challenges and future research opportunities related to silane coupling agent-enabled next-generation energy storage technologies are provided.