Back-Adhesive Hybrid Solid Electrolyte with Regulated Surface Adhesion Realizing Enhanced Interfacial Kinetics and Stability in Solid-State Sodium Metal Batteries

Achieving intimate interfacial contact and dendrite suppression at electrolyte interfaces is critical in order for solid-state sodium-metal batteries (SSSBs) to become next-generation energy storage systems. Herein, a surface adhesion regulation strategy using a Na₃Zr₂Si₂PO₁₂ (NASICON)–polymer hybrid approach is introduced to design laminated hybrid solid electrolytes (LHSEs) with asymmetric rigid-adhesive surfaces. This design simultaneously enhances interfacial kinetics at the cathode and improves anode stability. Experiments and DFT calculations show that a new NASICON–polymer interface phase reduces the energy barrier for Na⁺ transport, enhancing ion migration efficiency. The optimized SEs5040, comprising 50% NASICON and 40% NASICON hybrid solid electrolyte (HSE) heterogeneous layers, exhibits a critical current density of 1.5 mA cm^–2, and the Na/SEs5040/Na₃V₂(PO₄)₃ cell retains 86.2% capacity after 1795 cycles at 2 C. These findings offer insights into optimizing interfacial contacts and suppressing dendrites in SSSBs.