As demand grows for sustainable and high-performance energy storage, aqueous zinc-iodine batteries (ZIBs) have attracted attention due to their low cost, environmental friendliness, and high theoretical capacity. However, their practical implementation is hindered by challenges including zinc dendrite formation, corrosion at the anode, and the polyiodide shuttle effect at the cathode. Now, researchers from Nanyang Technological University, led by Professor Hong Jin Fan, have presented a novel strategy using a polycationic long-chain molecule (Pah⁺) as a dual-function electrolyte additive. This work offers valuable insights into the development of next-generation zinc-iodine batteries that can overcome these limitations.

Why This Matters

• Energy Efficiency: The polycationic additive enables synchronous regulation of both Zn anode and iodine cathode, addressing key issues that limit cycle life and efficiency.
• In-Situ Regulation: By modifying the electrolyte, this strategy avoids complex electrode modifications and maintains cost-effectiveness.
• Scalable Applications: The approach is validated in both coin cells and pouch cells, demonstrating its potential for practical energy storage systems.

Innovative Design and Features

• Polycationic Additive (Pah⁺): A low-cost, long-chain molecule that simultaneously stabilizes the Zn anode and immobilizes polyiodide species at the cathode.
• Interfacial Adsorption: Pah⁺ preferentially adsorbs on Zn and iodine surfaces, forming a protective layer that suppresses side reactions and shuttle effects.
• Electrostatic Locking: The cationic nature of Pah⁺ enables strong Coulombic interactions with anionic polyiodides, reducing their diffusion and self-discharge.

Applications and Future Outlook

• High Areal Capacity: The Zn-iodine battery delivers ~4 mAh cm^-2 at 1 C with 95% capacity retention over 1,000 cycles.
• Long-Term Stability: A pouch cell with 3 × 4 cm²cathode cycles over 300 times without significant capacity decay.
• Challenges and Opportunities: The review highlights the importance of electrolyte engineering in realizing stable Zn-iodine batteries. Future research will focus on optimizing additive concentration and exploring multifunctional molecules for enhanced performance.

This comprehensive study provides a roadmap for the development of stable and efficient zinc-iodine batteries using a simple yet effective electrolyte additive. It highlights the importance of interdisciplinary research in chemistry, materials science, and engineering to drive innovation in energy storage technologies. Stay tuned for more groundbreaking work from Professor Hong Jin Fan’s team at Nanyang Technological University!