Bulk MoS ₂ Anodes Engineered by Solid‐Phase Pre‐Sodiation for High‐Performance Sodium‐Ion Batteries

ABSTRACT Although bulk MoS 2 is a promising anode candidate for sodium‐ion batteries (SIBs), its practical deployment is severely restricted by low initial Coulombic efficiency (ICE) and structural instability caused by substantial volume expansion and phase changes. Conventional pre‐sodiation methods to address these issues often suffer from safety hazards, complex procedures, or poor scalability. Herein, a facile and safe solid‐phase pre‐sodiation strategy is proposed that allows for the large‐scale synthesis of pre‐intercalated MoS 2 (Na 0.02 MoS 2 ) within just 15 min. The incorporated Na + acts as an active reservoir, boosting the ICE to a remarkable 93.5%. In situ characterizations and theoretical calculations reveal that pre‐intercalated Na + not only expands the interlayer spacing for faster kinetics, but also triggers a premature 2H‐to‐1T phase transition, thereby preventing structural dissociation during deep cycling. Consequently, the anode delivers a high reversible capacity of 508.5 mAh g −1 and ultra‐long cycling stability (retaining 400 mAh g −1 after 5000 cycles at 10 A g −1 ). This work demonstrates a commercially viable pathway to upgrade transition metal dichalcogenides for advanced energy storage applications.