Designing a bridging solvation structure using recessive solvents for high energy density aqueous zinc-ion batteries with 88% depth of discharge zinc rechargeability†

Electrochemical and thermodynamic instability of zinc metal caused by corrosion hinder the further development of aqueous zinc ion batteries (AZIBs). Herein, we introduced a high electron acceptor Lewis acid as a recessive solvent and polar anions as intermediaries to form capsule-like solvation nanoclusters. In the presence of polar anions, the recessive solvent, which cannot dissolve zinc salts independently, was activated, resulting in the formation of a “recessive solvent-anion-H₂O” bridging structure. This structure further self-assembled into a nested configuration and encapsulated Zn(H₂O)₆ inside the nanocapsule, thereby effectively suppressing interfacial side reactions. Owing to its solvation structure features, rapid reaction kinetics and homogeneous Zn deposition was achieved. The modified electrolyte enabled symmetric cells to achieve a prolonged cycle lifespan of 3500 h under an ultra-high current density of 50 mA cm⁻² and over 1600 h even at a high DOD of 88.09%, surpassing those reported in previous studies. In addition, Zn//VOH batteries demonstrated decent cycling stability for over 1400 cycles with a low N/P ratio of 1.54, and a high energy density of 57.14 W h kg⁻¹ was achieved in an Ah-level pouch cell, further highlighting their feasibility in practical application.