Green and robust chitin hydrogel toward high-performance Zn anode for sustainable energy storage

Abstract

Aqueous zinc batteries (AZBs) have garnered significant attention for green energy storage due to their inherent advantages in high environmental compatibility and low cost. However, challenges such as uncontrollable Zn dendrite growth and detrimental side reactions at the Zn anode severely limit the practical application of AZBs. Here, we utilize chitin, an abundant and biodegradable marine polysaccharide, to address these challenges. Through a green alkaline/urea solvent system, the obtained chitin hydrogel exhibits rich polar groups, homogeneous nanopores, and excellent mechanical strength. These features promote the desolvation of hydrated Zn2+ ions, enhance Zn2+ ionic conductivity, and enable uniform Zn²⁺ deposition, effectively and simultaneously suppressing Zn dendrites formation and side reactions. The Zn anode demonstrates a cycle life of 2500 h at 1 mA cm–2/1 mAh cm–2, achieving an average coulombic efficiency (CE) of 99.6% over 2000 cycles. Significantly, life cycle assessment reveals that the chitin hydrogel outperforms conventional separators in environmental sustainability and cost efficiency, positioning it as a green option for sustainable AZBs.