Mn doping-induced structural and electrochemical optimization of MoS2/N-doped carbon composite anodes for high-performance sodium-ion batteries

The 2H-MoS 2 /N-doped carbon (2H-MoS 2 /NC) composite has demonstrated great promise as an anode material for sodium-ion batteries (SIBs); however, its rate performance and cycling capability are still limited by the intrinsically poor electronic conductivity and the scarcity of in-plane active sites in 2H-MoS 2 . In this paper, Mn doping is applied as an effective strategy to overcome these limitations. A Mn-doped 2H-MoS 2 /NC (Mn-2H-MoS 2 /NC) composite is successfully synthesized via a simple one-step hydrothermal-calcination process. Electrochemical evaluations show that the Mn-2H-MoS 2 /NC electrode delivers a reversible specific capacity of 301.42 mAh g –1 after 150 cycles at a current density of 1 A g –1 . Especially, even at a high current density of 5 A g –1 , a capacity of 131.66 mAh g –1 is retained after 500 cycles. This performance far exceeds that of the pristine 2H-MoS 2 /NC anode (51.12 mAh g –1 ). Experimental and theoretical analyses reveal that Mn doping not only serves as an effective microstructural regulator (expanding the interlayer spacing and reducing the stacking layer of MoS 2 ) but also intrinsically transforms MoS 2 from a semiconductor into a conductor while increasing the density of active sites within and on the MoS 2 lattice. These synergistic effects facilitate rapid electron transport, accelerate Na + adsorption and intercalation, and enhance the reversibility of the conversion reaction. Consequently, Na + storage kinetics is significantly improved, leading to the superior cycling stability and rate performance of the Mn-2H-MoS 2 /NC electrode.