Hierarchical Interface Enabled by a Guest‐Anionic Chemistry for High‐Rate Aqueous Zinc‐ion Batteries

Abstract The poor reversibility of the zinc anode caused by interfacial side reactions and dendritic growth poses significant constraints on the practical application of aqueous zinc‐ion batteries. Herein, a co‐solute, acesulfame potassium, with strongly polar, zincophilic guest anions is introduced into a conventional low‐concentration aqueous electrolyte. This regulation enhances the electrolyte‘s ionic conductivity and accelerates the desolvation process of zinc ions at the electrode/electrolyte interface. Furthermore, the introduced acesulfame anions give rise to the formation of a stable solid electrolyte interface with a hierarchical crystalline‐amorphous bilayer structure that effectively suppresses side reactions and allows for uniform zinc ion diffusion‐deposition. Results show that the zinc anode in the designed electrolyte possesses remarkable reversibility, achieving stable operation under a ultrahigh current density of 40 mA cm −2 and 67.6 % depth of discharge, surpassing most previous reports. Zn//I 2 full cells assembled with this electrolyte exhibit high rate capability (135.0 mAh g −1 at 20 A g −1 ) and remarkable lifespan (96.3 % capacity retention after 40,000 cycles at 10 A g −1 ). A large‐sized Zn//I 2 pouch cell is also demonstrated, delivering a total capacity of 170 mAh with 78.8 % capacity retention after 600 cycles at 3.3 mA cm −2 , highlighting the potential of the guest‐anionic chemistry in practical applications.