AlF₃-Enriched Interphase Design Enables Comprehensive Electrochemical Performance Enhancement in Al-Ion Batteries

Aluminum-ion batteries (AIBs) are promising for large-scale energy storage owing to their elemental abundance, low cost, safety, and high anode capacity. However, their development is hindered by the limited reversibility of Al plating/stripping on Al metal anodes and cathode structural degradation under high-voltage operation, resulting in short cycle life and limited energy density. These challenges originate from an incomplete understanding of how interphase components and properties regulate electrode reactions. Here, we systematically investigate the interphase properties in AIBs and reveal that AlF₃ exhibits the highest interfacial energy, mechanical strength against dendrite growth, and electrochemical stability with electron-blocking capability against parasitic reactions, making it an ideal artificial interphase component. Based on these findings, AlF₃-enriched artificial interphases are constructed in Al||graphene batteries, enabling 99.9% Al plating/stripping Coulombic efficiency with uniform deposition morphology. The Al||graphene full cell delivers a high specific capacity of 122.6 mAh g^-1, ultrahigh-rate capability (817 C, charged in 2.936 s), and long-term cyclability exceeding 100 000 cycles. This AlF₃-enriched interphase strategy establishes fundamental principles for designing high-performance AIBs.