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

초록

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 similar to 0.48 to similar 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 Li2S2/Li2S accumulation in the SEI to similar 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.

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