The Application of Carbon-Based Materials in Cathodes for High-Performance K-Se Batteries: A Review

Potassium–selenium (K-Se) batteries have emerged as a promising energy storage system in view of their high theoretical energy density and low cost. However, their practical application is restricted due to challenges such as polyselenide shuttling, low redox activity, and significant cathode volume expansion during cycling, leading to inferior Coulombic efficiency and a short cycling lifespan. Carbon-based materials, with their superior electronic conductivity, adjustable pore structures, and robust chemical stability, have been extensively studied and employed as cathode materials in K-Se batteries, demonstrating remarkable potential in addressing the above-mentioned issues. Considering the rapidly growing research interest in this topic in recent years, herein, we comprehensively summarize recent advances in the application of carbon-based materials as cathodes in K-Se batteries. First, we introduce the properties, key challenges, and optimization strategies of K-Se batteries, including encapsulating Se within carbon materials, engineering chemisorptive hosts, and electrocatalyzing redox reactions. Furthermore, we discuss the relationship between fabrication strategies, micro/nanostructures, and electrochemical performances. Finally, we propose future prospects for the rational design and application of carbon-based cathodes in K-Se batteries and other alkaline metal–chalcogen batteries.