Facile Self-Assembly of Coral-Like MXene-Sulfur Free-Standing Electrodes for Efficient Polysulfide Confinement and Accelerated Redox Kinetics.

Lithium-sulfur (Li-S) batteries are promising for high-energy-density applications but face challenges such as polysulfide shuttling and sluggish sulfur redox kinetics. In this study, we propose a facile low-cost hydrogen chloride-assisted gelation strategy to fabricate a free-standing, coral-like MXene/carbon nanotube (CNT) foam cathode at ambient temperature and pressure. This self-assembly process eliminates the need for high-temperature or high-pressure conditions, making it suitable for large-scale production. The hierarchical porous structure provides multiscale confinement and continuous ion/electron pathways, enhancing both polysulfide confinement and ion transport. The chloride-induced surface modification of MXene promotes a transition from 2D film-like to 3D particulate sulfur deposition, improving redox kinetics and mitigating electrode passivation. The resulting cathode delivers excellent electrochemical performance, achieving 775 mAh g-1 at 4 C with 74.5% retention after 500 cycles and maintaining 827 mAh g-1 at 0.5 C under practical conditions (high sulfur loading, lean electrolyte), with a low decay rate of 0.11% per cycle. This work demonstrates the potential of self-assembly and surface chemistry modulation in enhancing Li-S battery performance without the need for complex or energy-intensive synthesis.