A review of C-based cathode composites for advanced K–Se batteries

Abstract

Potassium–selenium batteries (KSeBs) are increasingly recognized as attractive energy-storage candidates thanks to their high theoretical energy density and relatively low production cost. Yet, their practical deployment remains limited. Issues such as the migration of soluble polyselenides, sluggish redox kinetics, and substantial cathode volume changes during charge–discharge cycles lead to poor coulombic efficiency (CE) and short service life. To overcome these obstacles, carbon (C)-based materials have received significant attention. Owing to their excellent electrical conductivity, tunable porosity, and strong chemical stability, they have been widely explored as cathode hosts for KSeBs and have shown considerable promise in mitigating the aforementioned drawbacks. Given the rapid expansion of research in this field, this review provides a comprehensive overview of recent progress in C-based cathodes for KSeBs. We first outline the fundamental characteristics of KSeBs, the major technical challenges, and common optimization approaches, such as confining Se within C scaffolds, introducing chemisorptive host structures, and employing catalytic strategies to accelerate redox reactions. We then examine how different fabrication methods and micro/nanostructural designs influence electrochemical behavior. Lastly, we offer perspectives on future directions for the intelligent design of C-based cathodes in KSeBs and broader applications in other alkali–metal chalcogen battery systems.