The development of cathode materials
with a high electric conductivity
and a low polarization effect is crucial for enhancing the electrochemical
properties of magnesium-ion batteries (MIBs). Herein, Mo doping and
nitrogen-doped tubular graphene (N-TG) introduction are carried out
for decorating VS4 (Mo-VS4/N-TG) via the one-step
hydrothermal method as a freestanding cathode for MIBs. The results
of characterizations and density functional theory (DFT) reveal that
rich sulfur vacancies are induced by Mo doping, and N-TG as a high
conductive skeleton material serves to disperse the active material
and forms a tight connection, all of which collectively improved the
electrical conductivity of electrode and increased the adsorption
energy of Mg2+ (−6.341 eV). Furthermore, the fast
reaction kinetics is also confirmed by the galvanostatic intermittent
titration technique (GITT) and the pesudocapacitance-like contribution
analysis. Benefiting from the synergistic effect of electrical conductivity
enhancement and rich vacancy introduction, Mo-VS4/N-TG
delivers a steady Mg2+ storage specific capacity of about
140 mAh g–1 at 50 mA g–1, outstanding
cycle stability (80.6% capacity retention ratio after 1200 cycles
under 500 mA g–1), and excellent rate capability
(specific capacity reaches 77.1 mAh g–1 when the
current density reaches 500 mA g–1). In addition,
the reversible reaction process, intercalation mechanism, and structural
stability during the Mg2+ insertion/extraction process
are confirmed by a series of ex situ characterizations.
This research provides a sustainable and scalable strategy to spur
the development of MIBs.