Engineering covalent triazine frameworks for high-performance lithium–sulfur batteries

Lithium-sulfur (Li-S) batteries are considered a promising next-generation energy storage system due to their outstanding theoretical energy density. Despite their advantages, the commercialization of Li-S batteries is constrained by the poor electrical conductivity, polysulfide shuttle effects, and sluggish redox kinetics. Covalent triazine frameworks (CTFs), a class of porous organic polymers featuring high nitrogen content, extended π-conjugation, and excellent thermal and chemical stability, have recently emerged as versatile materials to address these issues. This review summarizes the working principles and major challenges of Li-S batteries, along with various synthesis approaches for CTFs. Recent progress in applying CTFs as sulfur host materials, cathodes, and separators in Li-S batteries is discussed, emphasizing their multifunctional roles in suppressing polysulfide shuttling, improving electron/ion transport, and enhancing cycling stability. Finally, the current limitations and future research directions for CTF-based materials in Li-S batteries are highlighted. The objective of this review is to offer valuable insights for the rational design of advanced CTFs and promote their application in next-generation high-performance energy storage technologies.