Adsorptive and Catalytic Ti3C2S2 MXene for High‐Performance Lithium–Sulfur Batteries

Abstract MXenes have emerged as promising candidates for hosting sulfur in lithium-sulfur (Li-S) batteries due to their exceptional electrical conductivity. Despite recognition of the significant influence of functional groups on the MXene surface on sulfur conversion reactions, a clear experimental understanding remains elusive. This study unveils that Ti₃C₂ MXene functionalized with –S groups demonstrates superior capabilities in anchoring and catalyzing lithium polysulfides (LiPSs) compared to counterparts functionalized with –Cl and –F groups. The Ti₃C₂S₂ MXene is synthesized via the molten salt method, followed by functional group replacement. Ti₃C₂S₂ MXene exhibits robust chemisorption strength, effectively mitigating LiPS dissolution and shuttling. Additionally, it demonstrates remarkable electrocatalytic prowess for Li₂S deposition/decomposition, thereby enhancing reaction kinetics. As a result, Ti₃C₂S₂ MXene-modified separators allow Li-S cells to achieve a high capacity of 1305 mAh/g at 0.1 C, alongside excellent cyclic retention of ≈81% after 1000 cycles. Even with an S loading of 6.5 mg/cm², it attains a notable areal capacity exceeding 5.5 mAh/cm². This work underscores the potential of surface modification strategies in boosting the anchoring and electrocatalytic performance of Ti₃C₂S₂ MXene in Li-S batteries.