Synergetic impact of oxygen and vanadium defects endows NH4V4O10 cathode with superior performances for aqueous zinc-ion battery

Owing to multi-electron redox reactions and versatile cation storage capabilities, laminated structured metallic vanadate of NH4V4O10 (NHVO) has been regarded as a kind of promising cathode materials for aqueous Zn-ion batteries with satisfactory electrochemical performance. Nevertheless, the NHVO cathode is still limited by the sluggish electrochemical kinetics and structural instability. Here, defect engineering was conducted to introduce the vanadium (V) and oxygen (O) dual defects into NHVO cathode for improving electrochemical performance. As revealed experimentally and theoretically, the migration of Zn-ion inside V/O-defected NHVO cathode can be effectively fostered by increasing active sites, lowering the migration barrier and reducing Gibbs free energy, which are rooted in the synergy impact of the presence of O defect and V defect. As the consequence, the outstanding electrochemical performance has been achieved, which delivers higher capacity of 489 mAh g-1 at 0.5 A g-1 with the capacity retention of 98 % after 100 cycles and exhibits singular cyclic stability at 15 A g-1, maintaining reversible capacity of 198 mAh g-1 after 8000 cycles. This synergistic strategy paves an avenue for accelerating the application of HNVO-based cathode for aqueous Zn-ion battery with satisfactory electrochemical performance and lifespan, advancing the approach of "carbon neutrality" society.