Termination-engineered high-entropy MXenes as bifunctional catalysts for shuttle suppression in aluminum-sulfur batteries

Rechargeable Al-S batteries are attractive for scalable energy storage because Al and S are abundant and low cost, but their performance is limited by soluble polysulfide shuttling and sluggish conversion kinetics. Here, we use first-principles calculations to investigate termination-engineered high-entropy (HE) MXenes with -O, -OH, and mixed -O/-OH (“M”) terminations as multifunctional cathode additives for simultaneous polysulfide immobilization and catalytic conversion. Ab-initio molecular dynamics confirms the structural stability of all HE-MXene variants at 300 K, while projected density of states shows preserved metallic conductivity for efficient charge transport. Adsorption calculations for Al-polysulfides (Al₂S₃, Al₂S₆, Al₂S₁₂, Al₂S₁₈, and S₈) reveal consistently stronger binding on HE-MXenes than in DOL/DME electrolytes, indicating a thermodynamic driving force for suppressing dissolution-driven shuttle. Among the candidates, the mixed-terminated HE₂ MXene exhibits the strongest overall anchoring, supported by charge-density difference analysis showing pronounced interfacial charge redistribution without loss of metallic character. Van der Waals decomposition indicates that adsorption originates from balanced dispersion and polar/chemical interactions. Climbing-image nudged elastic band calculations for Al₂S₃ dissociation show termination-dependent kinetics: -OH termination gives the lowest barriers (∼0.96 and 0.88 eV), while mixed termination offers the best compromise between strong adsorption and reduced barriers (∼1.12 and 0.91 eV).