Zinc-based flow batteries, such as alkaline zinc–iron flow batteries (AZIFB), are gaining considerable interest in stationary energy storage applications due to their low cost, high safety, and high power density. A typical AZIFB employs Zn(OH)₄²⁻/Zn as the negative redox couple, and as such, it suffers from the formation of Zn dendrites during the charging process (that is, Zn electrodeposition), leading to deteriorated electrochemical performance. Despite tremendous efforts in tackling the issue, it remains a challenge to ensure controllable Zn electrodeposition while achieving high storage performance, especially under practical conditions. Now, Xianfeng Li and colleagues at the Dalian Institute of Chemical Physics and the University of Chinese Academy of Sciences engineer an interfacial bridge — based on an organic compound (ethylenediaminetetraacetic acid, EDTA) — between the negative electrode and the negolyte to address this challenge.