Vacancy‐Assisted Transformation of MoS₂ Nanosheets into Defective MoS_x Nanoclusters to Regulate Sodium‐Ion Electrode Functionality

Abstract Defect structure has attracted significant attention because of its importance as design factor for exploring high‐performance functional materials. This study reports a defect‐engineering strategy to optimize the electrode performance of transition metal dichalcogenides and a clear elucidation of the underlying mechanism on the benefit of defect engineering with cycling‐induced transformation into small nanoclusters. The intercalative hybridization of monolayered MoS₂ nanosheets with bulky tetraalkylammonium cations is effective for generating abundant crystal vacancies in the MoS₂ lattice and improving the sodium‐ion electrode performance, achieving one of the excellent performances among MoS₂‐based sodium‐ion anode materials. The improved electrode activity of the tetrapropylammonium−MoS₂ nanohybrid is ascribed to the vacancy‐assisted transformation from monolayered MoS₂ nanosheets into trimeric/dimeric MoS_x nanoclusters during electrochemical cycling. ²³Na/¹H magic angle spinning‐nuclear magnetic resonance analyses demonstrated that cycling‐induced defective MoS_x nanoclusters yields a complex Na environment with high ion mobility and enhanced electrolyte absorptivity, promoting the excellent electrode functionality of tetrapropylammonium‐assembled MoS₂ nanosheets.