Simultaneous Inhibition of Zn Dendrites and Polyiodide Ions Shuttle Effect by an Anion Concentrated Electrolyte Membrane for Long Lifespan Aqueous Zinc–Iodine Batteries

Abstract

Aqueous zinc−iodine (Zn−I 2 ) batteries have attracted extensive attention due to their merits of inherent safety, wide natural abundance, and low cost. However, their application is seriously hindered by the irreversible capacity loss resulting from both anode and cathode. Herein, an anion concentrated electrolyte (ACE) membrane is designed to manipulate the Zn 2+ ion flux on the zinc anode side and restrain the shuttle effect of polyiodide ions on the I 2 cathode side simultaneously to realize long-lifetime separator-free Zn− I 2 batteries. The ACE membrane with abundant sulfonic acid groups possesses a multifunctional amalgamation of good mechanical strength, guided Zn 2+ ion transport, and effective charge repulsion of polyiodide ions. Moreover, rich ether oxygen, carbonyl, and S−O bonds in anionic polymer chains will form hydrogen bonds with water to reduce the proportion of free water in the ACE membrane, inhibiting the water-induced interfacial side reactions of the Zn metal anode. Besides, DFT calculations and in-situ UV−vis and in situ Raman results reveal that the shuttle effect of polyiodide ions is also significantly suppressed. Therefore, the ACE membrane enables a long lifespan of Zn anodes (3700 h) and excellent cycling stability of Zn−I 2 batteries (10000 cycles), thus establishing a substantial base for their practical applications. KEYWORDS: aqueous zinc−iodine batteries, anion concentrated electrolyte membrane, guided Zn 2+ ion flux, free water, polyiodide ions shuttle effect

Cation‐Conduction Dominated Hydrogels for Durable Zinc–Iodine Batteries

“…This underscores the ability of the ─SO 3 − on CCH in hindering the shuttle effect by exerting an electrostatic repulsion on negatively charged iodine species. [55][56] Furthermore, we fabricated a Zn-I 2 pouch cell (3×3 cm) with a low N/P ratio of around 2.8. ZnI 2 was employed as the initial active material in cathode with an areal I 2 loading of ≈10 mg cm −2 (Figure S41, Support-ing Information).…”

Janus Binder Chemistry for Synchronous Enhancement of Iodine Species Adsorption and Redox Kinetics toward Sustainable Aqueous Zn–I2 Batteries

“…Aqueous zinc–iodine batteries (ZIBs) are widely regarded as highly promising contenders for energy storage devices in the field of power storage. This is primarily attributed to their exceptional properties, including a high theoretical specific capacity (211 mAh g –1 ), satisfying energy density, excellent rate performance, availability of abundant and cost-effective raw materials (iodine storage: 55 μg L –1 ), and excellent safety features. − Nevertheless, the ZIBs face certain limitations that hinder their potential for large-scale application, such as low conductivity and sluggish kinetics of the iodine cathode, the large volume expansion of the host, and the severe shuttle effect caused by polyiodide ions. − These factors contribute to a high self-discharge rate, low Coulombic efficiency, and a short cycle life of the ZIB devices. To address the multiple challenges mentioned above, a majority of the existing research endeavors have prioritized the following aspects: (i) rational design on cathodic iodine host, aiming at enhancing conductivity and catalytic kinetic process of iodine species conversion (from I 3 – to I – ), further boosting the redox activity during battery service, , (ii) a routine on metallic zinc anode protection and electrolyte alteration, involving optimization on specific composition of electrolytes to facilitate uniform deposition of Zn as well as stabilize reversible stripping by increasing the anode modification layer, adjusting the composition of electrolyte to promote uniform deposition of zinc, and protecting the anode from polyiodide attack, ,, and (iii) functional modification on the separator, in general, grafting appropriate functional terminations to regulate the flux of Zn 2+ which can impede the shuttling of polyiodide …”

Orientational Electrodeposition of Highly (002)-Textured Zinc Metal Anodes Enabled by Iodide Ions for Stable Aqueous Zinc Batteries

“…Electrochemical energy storage technologies are of significance for efficiently integrating sustainable natural sources. − Among various options, rechargeable aqueous Zn metal batteries (RAZMBs) are practically promising due to the Zn merits involving materials abundance, low-cost, high theoretical capacity (820 mAh g –1 ), and intrinsic safety in aqueous electrolytes. − However, conventional Zn anodes often suffer from poor reversibility ascribed to severe dendrite growth, hydrogen evolution reaction (HER), and Zn corrosion even in mild acidic or neutral aqueous electrolytes, hindering the industrialization of RAZMBs. − Moreover, the HER would induce loose Zn deposition, exacerbate electrolyte consumption, and increase the local pH environment near Zn to provoke the formation of inactive byproducts, resulting in low Zn utilization and rapid battery failure. − In addition, the dendric Zn growth with irregular morphology will inevitably deteriorate the parasitic reactions and render short circuits of batteries. − Strategies for alleviating these issues have been proposed focusing on constructing artificial protective layers on Zn, − formulating electrolyte compositions, − modifying separators, , and designing host structures. − …”