In‐Situ Constructed Multifunctional Interfacial Layer Enable Long‐Life and Enhanced Kinetic Anode for High‐Performance Aqueous Aluminum Batteries

ABSTRACT Rechargeable aqueous aluminum batteries (AABs) with high energy‐to‐price ratios, abundant element reserves, and intrinsic safety are promising candidates for large‐scale energy storage. However, the inherent hydrogen evolution reaction (HER) of aluminum (Al) metal anode with inferior kinetics irreversibly hinders their practical implementation. Herein, we propose, for the first time, a double interfacial layer on the Al anode with drastically reduced HER and accelerated kinetics for AABs. Benefiting from the large band gap of the dual‐interfacial layer (integration of Sn and SnS (SS‐Al)), the stable voltage window of the electrolyte is remarkably expanded with the potential negatively shifting from −2.34 to −2.98 V at −5.0 mA/cm 2 . Furthermore, the synergistic effect from both the SnS outer layer (lower desolvation energy barrier) and the Sn interlayer with improved aluminumophilic properties contributes to accelerated kinetics. Consequently, the optimized SS‐Al electrode maintains one of the best long‐term stability among interface‐modified Al anodes (more than 700 h at 0.05 mA/cm 2 with a low initial overpotential of 50.0 mV) in symmetric batteries. Practically, the large‐size full‐cell prototypes deliver high performance over 1,000 cycles at 1.0 A/g. Overall, this novel interface modification strategy provides a promising pathway for the anode development in AABs.