Synergistic Ion Sieve and Solvation Regulation by Recyclable Clay-Based Electrolyte Membrane for Stable Zn-Iodine Battery.

Abstract

The high dissolution of polyiodides and unstable interface at the anode/electrolyte severely restrict the practical applications of rechargeable aqueous Zn-iodine batteries. Herein, we develop a zinc ion-based montmorillonite (ZMT) electrolyte membrane for synergizing ion sieve and solvation regulation to achieve highly stable Zn-iodine batteries. The rich M-O band and special cation-selective transport channel in ZMT locally tailor the solvation sheath around Zn²⁺ and therefore achieve high transference number (<i>t</i>_<i>+</i> = 0.72), benefiting for uniform and reversible deposition/stripping of Zn. Meanwhile, the mechanisms for three-step polyiodide generation and shuttle-induced Zn corrosion are highlighted by <i>in situ</i> characterization techniques. It is confirmed that the strong chemical adsorption between O atoms in ZMT and polyiodides species is the key to effectively inhibit the shuffle effect and side reactions. Consequently, the ZMT-based Zn-iodine battery delivers a high capacity of 0.45 mAh cm^-2 at 1 mA cm^-2 with a much improved Coulombic efficiency of 99.5% and outstanding capacity retention of 95% after 13 500 cycles at 10 mA cm^-2. Moreover, owing to its high durability and chemical inertness and structural stability, ZMT-based electrolyte membranes can be recycled and applied in double-sided pouch cells, delivering a high areal capacity of 2.4 mAh cm^-2 at 1 mA cm^-2.