Atomic Co-driven catalysis in MoS₂ for accelerated charge transfer and stable interfacial chemistry in sodium-ion batteries

Maximizing initial Coulombic efficiency (ICE) is crucial for the practical deployment of sodium-ion batteries (SIBs), yet remains challenging due to uncontrolled interfacial side reactions and sluggish charge transport. Here, we present an in situ electrochemical catalysis strategy enabling atomic-level Co doping in MoS₂, which simultaneously regulates its electronic configuration and interfacial chemistry. The engineered Co–S–C catalytic sites accelerate the cleavage of P–F and C–O bonds from NaPF₆ and diglyme, respectively, inducing rapid formation of an ultrathin, highly conductive inorganic-rich SEI layer. This suppresses irreversible parasitic reactions and drastically enhances ICE to an unprecedented 96 %. Additionally, Co incorporation drives a 2H-to-1T phase transition via Mo 4d orbital reorganization, weakening Mo–S bonds and boosting Na⁺/electron transport. The resulting Co–MoS₂/SC anode delivers exceptional electrochemical performance, with 288 mAh g⁻¹ at 20 A g⁻¹ and 96 % capacity retention over 2000 cycles at 10 A g⁻¹. This work offers a powerful strategy for interfacial catalysis-driven phase engineering, unlocking new opportunities for high-efficiency, high-rate sodium storage.