Holistic optimization strategies for advanced aqueous zinc iodine batteries

Zinc-based batteries are gaining prominence as promising alternatives to lithium-ion batteries (LIBs) in the pursuit of Net-Zero goals, owing to their cost-effectiveness, scalability, and reduced resource dependency. Aqueous rechargeable zinc-iodine (Zn-I2) batteries, in particular, are emerging as an enticing choice for future energy storage systems, thanks to their eco-friendly nature, impressive theoretical capacity, and impressive energy/power density. Nevertheless, several challenges, including the well-known polyiodide shuttling phenomenon, suboptimal thermodynamic stability, and issues like corrosion and dendrite formation on Zn metal anodes, impede their practical implementation. Tremendous progress has been achieved to circumvent these issues in recent years, though a comprehensive review article for both entry-level and experienced researchers is still lacking up to date. This review aims at discussing the fundamentals, challenges, and solutions to enable the understanding of electrochemistry mechanisms, and systematically summarizing the past, present, and future technologies and strategies involving iodine cathode design and modification, interlayer construction/separator modification, electrolytes optimization, and Zn metal anodes protection. Additionally, based on recent achievements, some promising directions and efforts for developing high-performance Zn−I2 batteries are proposed to accelerate commercial applications.