Skin‐Passivated Porous MXene Hosts Enable Fast and Durable Lithium Metal Anodes for High‐Energy Lithium–Sulfur Batteries

Lithium metal anodes (LMAs) could unlock the full energy potential of lithium–sulfur batteries (LSBs), but remain limited by parasitic interfacial reactions, dendrite growth, and poor reversibility under high Li flux. Herein, a skin‐passivated porous MXene host (SP‐MXH) is designed to decouple solvent access from Li + transport. An ultrathin polyethylene glycol dimethacrylate (pEGDMA)‐derived skin‐passivating surface structure (Skin‐PASS) suppresses solvent penetration and outer‐surface side reactions while directing Li + flux into the porous MXene framework. This interfacial control increases the Li + transference number from ∼0.48 to ∼0.59 and induces uniform internal lithium plating, resulting in low polarization (16–204 mV at 1–30 mA cm −2 ), 99.6% Coulombic efficiency, and stable cycling for over 1,000 cycles. In LSB full cells, SP‐MXH suppresses polysulfide shuttle reactions, limits Li 2 S 2 /Li 2 S accumulation in the SEI to ∼5% after 100 cycles and delivers 2,100 W h kg −1 (based on sulfur mass) with 70% capacity retention after 300 cycles. Interfacial skin engineering thus offers a practical route to fast and durable LMAs for high‐energy LSBs.