Progress, pitfalls, and prospects in emerging materials for aluminum-sulfur batteries

Aluminium-sulfur (Al-S) batteries have emerged as a promising post-lithium alternative owing to aluminium's abundance, safety, and high theoretical capacity. However, their practical implementation is impeded by key challenges such as sluggish Al³⁺ redox kinetics, polysulfide shuttle effects, and volumetric changes of the electrodes during cycling. This review critically analysis recent advancements in host structural design engineering, new electrocatalysts, and electrolyte aimed at overcoming these limitations. Advanced host frameworks include 2D/3D porous structures, MXene-based multilayers, and single-atom doped materials that facilitate efficient sulfur confinement, enhance conductivity, and catalyse redox reactions. Embedded catalysts like Mo₆S₈ and CoS₂ within nitrogen-doped carbons lower the decomposition barrier of Al₂S₃, promote stable Al-polysulfide conversion, and extend cycle life. Electrolyte optimization through ionic liquids, molten salts, and halide-modified systems further enhances ion mobility, suppresses passivation, and supports stable sulfur utilization. Emerging hybrid electrolytes combining high-donicity solvents with ionic or molten salt phases offer synergistic gains in redox kinetics and thermal stability. Density functional theory (DFT) guided designs elucidate key host-electrolyte-polysulfide interactions, revealing pathways for tailored material selection and performance enhancement. These integrated strategies pave the way for high-energy, long-lasting Al-S batteries that perform reliably at both room and elevated temperatures.