Defect-engineered composite with ammonium vanadate and 1T-MoS₂ for superior aqueous zinc-ion battery applications

Aqueous zinc-ion batteries (AZIBs) are competitive energy-storage systems owing to their high ionic conductivity, safety, low cost, and eco-friendliness. Vanadium-based oxides have gained research interest as cathode materials for AZIBs because of their high capacities derived from their multivalent states and layered structures. However, vanadium-based oxides continue to exhibit poor performance as electrodes owing to critical issues, such as structural collapse, cation trapping, and poor electrical conductivity, which limit their practical application. Defect-engineered composite cathode materials consisting of (NH4)(2)V6O16 center dot 1.5H(2)O (NVO) nanorods and metallic 1T-MoS2 nanosheets were fabricated using a sonochemical method. NH4+ and H2O were co-intercalated into the NVO interlayer and served as pillars for stabilizing the layered structure. The 1T-MoS2 nanosheets promote fast charge transfer by providing conductive networks to the NVO. Furthermore, the oxygen defects in the NVO lattice weaken the electrostatic attraction between the inserted Zn2+ cations and the lattice oxygen layers, facilitating reversible Zn2+ (de)intercalation during charging-discharging. Consequently, the Od-NVO/Oi-MoS2 electrode exhibited a high capacity of 370.5 mAh/g at a current density of 0.2 A/g. In addition, it exhibited a high capacity of 141 mAh/g and maintained 92.5% of its initial capacity after 2000 cycles at 10 A/g.