Elemental halogen cathodes for aqueous zinc batteries: mechanisms, challenges and strategies

Abstract

The inherently intermittent and regional nature of renewable energy generation drives the growth of large-scale electrical energy storage systems. Aqueous Zn-based batteries matched with conversion-type cathodes have attracted increasing attention owing to their cost effectiveness, abundant reserves, intrinsic safety, and relatively long lifetime. Halogens with unique electron configurations possess an abundance of chemical valence states, high redox potential, and relatively high theoretical capacity and have shown great promise as cathode materials. However, many intractable challenges need to be resolved, such as the shuttle effect and slow kinetics. In this review, redox mechanisms and fundamental challenges associated with aqueous zinc–halogen batteries are summarized first. Subsequently, the research issues and progress related to halogen cathode materials are discussed. Finally, we present a forward-looking perspective for promising aqueous zinc–halogen batteries. By furnishing a nuanced understanding of recent advancements and challenges in this field, the review aspires to offer valuable guidance to researchers, ultimately facilitating the practical application of aqueous zinc–halogen batteries.