Emerging multifunctional polymer binder materials for advancing lithium-sulfur battery performance: a review.

Lithium-sulfur (Li-S) batteries have emerged as a strong next-generation energy storage technology, mainly due to their high theoretical energy density and low cost. However, their commercialization has not been possible due to the intrinsically low conductivity of sulfur, severe volume expansion and polysulfide shuttling during cycling, leading to rapid capacity fading and low coulombic efficiency. While extensive research is focused on the development of advanced cathode hosts and electrolyte optimization, the importance of polymer binders in stabilizing Li-S cathodes has only recently been recognized as a crucial direction to further improve the performance of Li-S batteries. This review provides a comprehensive overview of recent progress in polymer binder engineering for Li-S battery cathodes. The review highlights the transition from conventional inert binders to multifunctional systems. Herein, we discuss different types of multifunctional binders, including polar binders for polysulfide confinement, conductive binders for improved charge transport and crosslinked or elastomeric networks for enhanced mechanical durability. Emerging approaches, including supramolecular, self-healing, bio-based, water-processable and binder-free strategies, are also critically evaluated. By correlating binder chemistry and architecture with electrochemical performance, this review outlines the key design principles and their advantages, limitations and future directions towards practical, high-performance and scalable Li-S battery technologies.