Design Bridging Solvation Structure by Recessive Solvents for High Energy Density Aqueous Zinc-Ion Batteries with 88% Depth of Discharge Zinc Rechargeability

Abstract

Electrochemical and thermodynamic instability of zinc metal represented by the corrosion reaction have hindered aqueous zinc ion batteries (AZIBs) further development. Herein, we introduced a high electron acceptor Lewis acid as 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 is activated, resulting in the formation of a "recessive solvent-anion-H2O" bridging structure. This structure further self-assembles into a nested configuration and encapsulates Zn(H₂O)₆ inside nanocapsule, effectively suppressing interfacial side reactions. Attributed to its solvation structure features, rapid reaction kinetics, and homogeneous Zn deposition can be achieved. The modified electrolyte enables symmetric cells to achieve prolonged cycle lifespan of 3500 h under ultra-high current density of 50 mA cm⁻² and over 1600 h even at high DOD of 88.09%, surpassing most reported studies. In addition, Zn//VOH batteries demonstrate decent cycling stability over 1400 cycles with a low N/P ratio of 1.54 while a high energy density of 57.14 Wh/kg can be achieved in Ah level pouch cell, further highlighting its practicalization capability.