Tannin acid induced anticorrosive film toward stable Zn-ion batteries

Aqueous Zn-ion batteries (AZIBs) have been regarded as a promising next-generation energy storage system. However, the poor reversibility of Zn anodes with serious dendrite growth and parasitic reactions degrades the battery performance. Inspired by the anticorrosion strategy for metal protection, an extremely simple and cost-effective method of soaking Zn plate in tannin acid (TA) solution is applied to design ZnTA anticorrosive film on Zn anodes. Robust chemical interaction between Zn and phenolic hydroxyl groups in TA molecules endows ZnTA with the excellent film-forming capacity of ensuring uniform surface and desirable coverage on Zn anodes. A remarkable suppression of parasitic hydrogen evolution during Zn plating is available by ZnTA@Zn anodes, evidenced by in-situ electrochemical gas chromatography (EC-GC). The Symmetric cells with ZnTA@Zn anodes show long-term stability of over 4500 cycles under an ultra-high current density of 30 mA cm-, 2 verifying the excellent reversibility ZnTA@Zn anodes. Besides, ZnTA anticorrosive film also demonstrates significant capacity to suppress the Zn corrosion resulted from shuttling polyiodide. Consequently, highly-reversible Zn-I-2 batteries with excellent rate performance and ultra-long lifespan (20,000 cycles at 6 A g-1) are achieved with ZnTA@Zn anodes. This finding emphasizes the protective mechanism of anticorrosive films against electrolyte/polyiodide corrosion which contributes to the highly-reversible Zn anodes.

Automated summary

This study proposes a simple and cost-effective method of designing a ZnTA anticorrosive film on Zn anodes. The film demonstrates excellent uniformity and coverage, resulting in remarkable suppression of hydrogen evolution and corrosion. As a result, highly-reversible Zn-I-2 batteries with excellent rate performance and ultra-long lifespan are achieved.