First-principles insights into selenium and sulfur doping on Ti₂CO₂ MXene for mitigating the shuttle effect in lithium–sulfur batteries

Abstract Lithium–sulfur (Li–S) batteries are promising next-generation energy storage devices due to their high energy density, cost-effectiveness, and environmental friendliness. However, their practical application is hindered by the shuttle effect of lithium polysulfides (Li 2 S x ) and the poor electrical conductivity of the sulfur cathode. In this study, we employ first-principles density functional theory calculations to investigate the effects of selenium (Se) or sulfur (S) doping on Ti 2 CO 2 MXene as an anchoring material to mitigate these challenges. Our findings reveal that substituting oxygen with Se or S enhances the electronic conductivity of Ti 2 CO 2 by transforming it into a metallic conductor. The adsorption energies of various Li 2 S x clusters ( x = 1, 2, 4, 6, 8) on the doped MXenes demonstrate significantly improved binding, particularly for low-sulfur content clusters, which is crucial for inhibiting the shuttle effect. Furthermore, charge transfer analysis confirms that Se or S doping enhances the interaction between Li 2 S x and the MXene surface, promoting better electrochemical performance. These results establish Se or S doping as an effective strategy for optimizing MXene-based anchoring materials in high-performance Li–S batteries.