Engineering Strategies for Stable and Long-Life Alkaline Zinc-Based Flow Batteries

Abstract

Alkaline zinc-based flow batteries (ZFBs) are emerging as promising candidates for grid-scale energy storage owing to the high abundance and low cost of zinc, relatively high cell voltages, inherent safety, and environmental compatibility. However, their practical deployment is critically hindered by zinc anode-related degradation. This review provides a comprehensive, mechanism-based summary of recent progress in stabilizing zinc anodes in alkaline ZFBs. Zinc deposition mechanisms and failure modes in alkaline media are clarified, emphasizing the intrinsic links among dendrite formation, passivation, hydrogen evolution, corrosion, and “dead Zn” accumulation. The stabilization strategies are classified into three main categories: (1) Electrode engineering, utilizing 3D conductive scaffolds to homogenize current and ion fluxes, zincophilic sites to direct nucleation, along with protective coatings and substrate alloying to suppress side reactions. (2) Electrolyte engineering, encompassing the modulation of electrochemical kinetics, interfacial regulation via electrostatic shielding, and the chemical reactivation of “dead Zn”. (3) Membrane engineering, focusing on functionalized architectures to redistribute zincate diffusion, enhance ion selectivity against crossover, and mechanically block dendrite penetration. Collectively, these strategies provide design guidelines for developing alkaline ZFBs with long lifetime and scalability for large-scale energy storage.