MXene (Ti₃C₂T _x ) mediated multiscale electrolyte regulation enables robust interphase for dendrite-free solid-state...

Solid-state sodium metal batteries (SSMBs) have garnered significant attention for next-generation high-safety energy storage, but their practical application is severely hindered by sluggish ion transport kinetics in solid electrolytes and the unstable sodium metal/electrolyte interface. Herein, we employ Ti₃C₂T _x MXene with abundant surface polar terminations as a multiscale regulator to construct composite solid electrolytes (P-OGN@NZSP/MXene). At the micro-nano scale, MXene serves as a two-dimensional scaffold for uniform Na₃Zr₂Si₂PO₁₂ (NZSP) nanoparticle loading and continuous Na⁺ transport network construction. At the molecular scale, MXene modulates the Na⁺ solvation structure, weakening Na⁺-polymer coordination and promoting an anion-rich solvation sheath, which enables in situ formation of a dense inorganic-rich solid electrolyte interphase. This synergistic design yields over 1000 h of stable cycling in Na symmetric cells with ∼16 mV polarization, and 91.2% capacity retention after 1000 cycles at 0.3C in Na‖Na₃V₂(PO₄)₃ full cells. This work offers valuable insights into the multiscale regulation of composite solid electrolytes through the incorporation of two-dimensional polar nanosheets.