New Materials for Lithium–Sulfur Batteries: Challenges and Future Directions

This review explores recent advances in lithium–sulfur (Li–S) batteries, a promising next-generation energy storage technology known for their exceptionally high theoretical energy density (~2,500 Wh/kg), cost-effectiveness, and environmental advantages. Despite their potential, commercialization remains limited by key challenges such as the polysulfide shuttle effect, sulfur’s insulating nature, lithium metal anode instability, and thermal safety concerns. This review provides a comprehensive and forward-looking perspective on emerging material strategies—focusing on cathode, electrolyte, and anode engineering—to overcome these barriers. Special emphasis is placed on advanced sulfur–carbon composites, including three-dimensional graphene frameworks, metal–organic frameworks (MOFs), covalent organic frameworks (COFs), and MXene-based materials, which have demonstrated significant improvements in sulfur utilization, redox kinetics, and cycling stability. Innovations in electrolytes—particularly solid-state and gel polymer systems—are discussed for their roles in suppressing polysulfide dissolution and enhancing safety. The review also examines lithium metal anode protection strategies, such as artificial SEI layers, 3D lithium scaffolds, and lithium alloying. Finally, it discusses critical issues related to large-scale manufacturing, safety, and commercial scalability. With ongoing innovation in multifunctional materials and electrode design, Li–S batteries are well positioned to transform energy storage for electric vehicles, portable electronics, and grid-scale systems.