Engineering Oxygen Vacancies on VO₂ Multilayered Structures for Efficient Zn²⁺ Storage

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Vanadium dioxide (VO2) exhibits potential as a cathode for aqueous zinc-ion batteries (ZIBs) due to its structural properties and high theoretical capacity.
• However, its practical application is limited by sluggish reaction kinetics and structural instability caused by strong Zn2+ interactions.

Purpose of the Study:

• To investigate the effect of oxygen defect engineering on VO2 performance in aqueous ZIBs.
• To optimize oxygen vacancy concentration for enhanced electrochemical properties.

Main Methods:

• A facile one-step hydrothermal method was employed to synthesize oxygen-defect VO2 (Od-VO2) by adjusting ascorbic acid concentration.
• The electrochemical performance of Od-VO2 as a cathode material was evaluated in aqueous ZIBs.

Main Results:

• Oxygen vacancies were shown to provide additional active sites for Zn2+ storage and reduce the electrostatic barrier for Zn2+ transport.
• An optimal oxygen vacancy concentration in Od-VO2 resulted in a high capacity of 380 mAhg-1 at 0.2 A g-1.
• The optimized cathode demonstrated excellent cycle stability (92.6% retention after 2000 cycles at 3 A g-1) and high energy density (197 Wh kg-1 at 0.641 kW kg-1).

Conclusions:

• Defect engineering, specifically introducing oxygen vacancies, is an effective strategy to overcome the limitations of VO2 in aqueous ZIBs.
• The developed Od-VO2 cathode material offers a promising pathway towards high-performance and stable aqueous ZIBs.