Conformal thioaluminate/aluminate polymer protective layer enables dendrite-free lithium metal batteries

Dendrite growth associated with highly reactive surface are the primary challenges for Li metal anode. Herein, an effective thioaluminate/aluminate polymer is developed as an artificial protective layer for stabilizing Li metal anode. This protective layer, enriched with aluminium-sulfur (Al-S) and aluminium-oxygen (Al-O) polar bonds, exhibits remarkable lithium ions transference number (tLi+ = 0.7), high exchange current density, superior electrolyte wettability and high-volume adaptability. This allows for the uniform flow of lithium ions and effectively inhibits the formation of lithium dendrites. This approach affords a hermetic Li metal anode with high columbic efficiency of 99.86 % and extended plating/striping reversibility for 3000 h at 2 mA cm−2@1 mAh cm−2 or 1200 h at 5 mA cm−2@5 mAh cm−2. The protected Li metal anode delivers a prolonged lifespan and rate capability in the LiFePO4 full batteries, showcasing its potential for practical application.