Multi‐Ionic Capacity of Zn‐Al/V6O13 Systems Enable Fast‐Charging and Ultra‐Stable Aqueous Aluminium‐Ion Batteries

Abstract Rechargeable, cost‐efficient aqueous aluminium‐ion batteries (AAIBs) possess abundant trivalent charge carriers with high volumetric energy densities. However, the rapid and irreversible formation of Al 2 O 3 passivation films on aluminium‐ion (AI) anodes while using aqueous electrolytes limits their development. Herein, Zn metal was used as the anode, and Al 3+ was locally deposited on the Zn anode during charging. V 6 O 13 with a mixed vanadium state of V 4+ /V 5+ was chosen as the cathode because of its efficient ion diffusion (solid state) and high electron conductivity. The Zn−Al/3 M Al(OTF) 3 /V 6 O 13 cell exhibited high current density and excellent long‐term cycling stability, demonstrating a very high specific capacity of ∼100 mAh g −1 at a current density of 3 A g −1 and Coulombic efficiency of ∼100 % with reversible stability over 1400 cycles. Furthermore, the V 6 O 13 cathode exhibited a multi‐ionic capacity of Zn 2+ ‐ and H + ‐ions during the Al deposition/dissolution reaction in AAIBs, demonstrating high safety and stability for fast charging.