A Synchronous Strategy to Zn-Iodine Battery by Polycationic Long-Chain Molecules

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Aqueous zinc-iodine batteries (ZIBs) suffer from Zn anode corrosion, dendrite growth, and polyiodide shuttle effect, limiting cycle stability and causing self-discharge.
• Electrolyte engineering is a cost-effective strategy for ZIBs, especially a synchronous method for modulating both anode and cathode.
• Previous studies often neglected simultaneous anode and cathode modulation.

Purpose of the Study:

• To introduce a low-cost, dual-function electrolyte additive for ZIBs.
• To investigate the synchronous stabilizing effect of poly(allylamine hydrochloride) (Pah+) on both Zn anode and polyiodide species.
• To demonstrate the improved performance of ZIBs using Pah+.

Main Methods:

• Utilized cationic poly(allylamine hydrochloride) (Pah+) as an electrolyte additive in aqueous ZIBs.
• Investigated the dual-functionality of Pah+ in stabilizing the Zn anode and immobilizing polyiodide anions.
• Fabricated and tested Zn-iodine coin cells and pouch cells with Pah+ under various conditions.

Main Results:

• The Pah+ additive effectively stabilized the Zn anode and suppressed the shuttle effect of polyiodide anions.
• Zn-iodine coin cells with Pah+ achieved stable cycling of 1000 cycles at 1 C.
• A 3 × 4 cm² pouch cell demonstrated over 300 cycles with insignificant capacity decay.

Conclusions:

• Poly(allylamine hydrochloride) (Pah+) is a highly effective and low-cost dual-function electrolyte additive for aqueous ZIBs.
• Pah+ enables synchronous modulation of both anode and cathode, significantly enhancing battery performance and cycle stability.
• The findings pave the way for practical and stable aqueous ZIBs through advanced electrolyte engineering.