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, polysulfides 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.