Iminodiacetate Chelated Zinc Complex Electrolyte Enables High‐Voltage and Long‐Life Zinc‐Based Flow Batteries

Abstract

ABSTRACT Conventionally, lowering the Zn plating/stripping potential relies on strongly alkaline electrolytes that convert Zn 2+ into zincate species. However, such conditions often exacerbate Zn corrosion and severe dendrite growth. Here, we introduce an iminodiacetate (IDA 2− )‐based coordination strategy that enables reversible Zn plating/stripping under mildly alkaline conditions (pH ∼12). The hexacoordinated [Zn(IDA) 2 ] 2− shifts the Zn plating/stripping potential to −1.17 V versus SHE. A demonstrated zinc‐iodine flow battery delivers a voltage of ∼1.7 V with a peak power density of 561.5 mW cm −2 and sustains cycling over 700 cycles at 100 mA cm −2 with Zn areal capacity of 90 mAh cm −2 . This strategy is further validated in a zinc‐iron redox flow battery, achieving an operating voltage of ∼1.6 V with average Coulombic efficiency of 99.3% over 750 cycles. Collectively, these results suggest that the proposed coordination chemistry offers a promising avenue toward the development of high‐voltage long‐life zinc‐based redox flow batteries.