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

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//I₂ 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//I₂ 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.