Evolution of host materials for halogen-based batteries

Halogen-based batteries (HBBs) exhibit promising potential for advanced energy storage demands due to their superior theoretical capacities and substantial raw material abundance. However, the inherent limitations associated with halogen chemistry severely impede the practical application of HBB technology. Host material engineering has emerged as an effective solution to address problems, including slow charge-transfer kinetics, unstable halogen redox, and undesired active species shuttling in HBBs. This review systematically delineates recent progress in host material development for advanced HBBs. Initially, the theoretical framework of HBBs is established by tracing evolutionary history, delineating battery configurations, and clarifying the fundamental halogen-based energy storage principles. Subsequently, the challenges associated with halogen conversion chemistry, the essential criteria for host materials, and current host design patterns are outlined. Finally, this review identifies the persistent challenges in current host applications and proposes strategic future research directions for developing high-performance next-generation HBBs.