Key Issues and Strategies in Aqueous Static Zinc–Halogen Battery Design

Aqueous zinc-halogen batteries have emerged as leading candidates for next-generation energy storage systems, owing to their inherent advantages such as high theoretical energy density, enhanced safety, and cost-effectiveness derived from earth-abundant zinc and halogen elements. However, the practical implementation of halogen cathodes faces major challenges, including intrinsically low electrical conductivity, the pronounced shuttle effect of soluble polyhalide intermediates, severe corrosion, and competing hydrolysis reactions. These issues call for innovative and rational material design strategies across all battery components. Accordingly, realizing practical zinc-halogen batteries requires a comprehensive understanding that bridges fundamental halogen redox chemistry with targeted material engineering solutions. This review systematically examines the crucial connection between the electrochemistry of halogens and the practical design of battery materials in zinc-halogen systems. Key challenges are first addressed, including stabilizing halogen cathodes, managing reactive halogen species, and optimizing cell configurations. Subsequently, recent pivotal strategies are summarized, including the development of advanced halogen host materials, halogen complexing agents, catalysts for halogen electroactivity, multi-electron redox processes, and electrolyte/separator design. Finally, the essential practical considerations that influence achievable energy density are discussed: such as current collector stability, active halogen ratio, and electrolyte weight/cost, which are critical for realistic performance evaluation and the commercialization of zinc-halogen battery technologies.