Boosting Zinc Storage Capacity of MoO 3 Nanobelts by Modulating Molybdenum Sites via Anionic Sulfur Doping

Molybdenum trioxide (MoO 3 ) has emerged as a promising cathode material for aqueous zinc‐ion batteries (AZIBs) owing to its high theoretical capacity and distinctive layered structure. Nevertheless, its practical implementation in energy storage devices is constrained by limited electrochemical activity and sluggish Zn 2+ ion diffusion kinetics. Overcoming these challenges is essential for realizing the full potential of MoO 3 ‐based electrodes in high‐performance AZIBs. This study proposes an anionic sulfur doping strategy to modulate the covalency of chemical bonds around Mo sites in MoO 3 nanobelts, thereby substantially enhancing their charge storage capacity. Sulfur doping not only introduces low‐valence Mo sites, improving the electronic conductivity of the material, but also provides additional ion storage sites. The aqueous zinc‐ion battery (S‐MoO 3‐ x //Zn) constructed with the optimized S‐doped MoO 3‐ x (named as S‐MoO 3‐ x ) as the cathode and commercial zinc foil as the anode delivers a high specific capacity of 254 mAh g −1 at a current density of 1 A g −1 , along with excellent cycling stability, retaining 65.3% of its capacity after 500 cycles, outperforming other recently reported aqueous zinc‐ion battery systems. This work provides a valuable reference and motivation for the further development of molybdenum‐based and other layered materials in high‐performance aqueous zinc‐ion batteries.