MXene porous engineering as lithium-ion kinetic pump for durable lithium-sulfur batteries

Lithium-sulfur (Li-S) batteries have attracted considerable attention due to their splendid theoretical energy density, but their development is impeded by the polysulfides shuttling effect and slow conversion kinetics. The incorporation of MXene-based porous structure has emerged as a promising strategy to address these challenges, as it can provide additional catalytic sites for polysulfides. In this study, MXene was prepared using the molten salt method, offering an effective strategy to the safety concerns associated with traditional acid etching, while enhancing the structural properties of MXene. However, this method often results in a reduction of active sites, limiting the optimal sulfur loading. To address this issue, the porous Ti3C2Tx (designated as K-Ti3C2Tx) was fabricated by stirring multilayer Ti3C2Tx in KOH solution. This structure exhibits abundant anchoring sites for polysulfides and accelerates the bidirectional conversion reaction of sulfur. Through visual adsorption and GITT testing, the Li-S batteries with K-Ti3C2Tx@S cathode exhibit an impressive initial discharge capacity of 1155 mAh g-1 at 0.1 C. Moreover, the K-Ti3C2Tx@S cathode demonstrates excellent cycling stability at 1 C, with a minimal capacity decay rate of only 0.047 % per cycle after 500 cycles, offering a novel perspective on enhancing the performance of Li-S batteries through porous structure engineering.