A Multifunctional Solid Electrolyte Design for Efficient Lithium-Ion Transport and Dendrite-Resistant Lithium-Metal Batteries

Solid polymer electrolytes are widely regarded as promising candidates for next-generation Li-metal batteries owing to their intrinsic safety and compatibility with high-energy-density systems. However, their practical implementation is still hindered by limited ionic conductivity, interfacial instability, and uncontrolled Li-dendrite growth. To address these challenges, a multifunctional tri-layer composite solid electrolyte was designed by integrating interfacial engineering and mechanical reinforcement within a hierarchical architecture. The electrolyte consists of ion-conducting polymer outer layers and a reinforced intermediate layer containing a functionalized ceramic filler and an elastomeric polymer additive. The surface-modified ceramic phase enhances compatibility with polymer matrix, promoting uniform dispersion and improved interfacial characteristics. Simultaneously, ceramic filler contributes to formation of efficient Li⁺-ion transport pathways while suppressing polymer crystallization, thereby facilitating ion migration. The elastomeric component further improves mechanical compliance, relieves localized stress concentrations, and helps resist dendrite-induced damage. Through the synergistic combination of these functionalities, tri-layer electrolyte achieves enhanced electrochemical and mechanical properties. Among the investigated formulations, the optimized composite electrolyte displayed superior electrochemical characteristics, including enhanced ionic conductivity, efficient Li⁺-ion transport, and broad electrochemical stability. Full-cell testing demonstrated high reversible capacity and excellent cycling durability, while symmetric-cell measurements confirmed prolonged dendrite-free operation under repeated cycling conditions. The synergistic combination of ceramic reinforcement, interfacial engineering, and mechanical stress regulation provides a promising pathway toward robust, high-performance solid-state Li-metal batteries