Controlled Heterovalent Vanadium Ion Coordinated Flower-Shaped Supramolecules Cathode for Zinc-Ion Storage

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Vanadium-based materials are promising for zinc-ion batteries (ZIBs) due to their multiple oxidation states and redox activity.
• Controlled synthesis of heterovalent vanadium oxides for ZIBs remains a significant challenge.

Purpose of the Study:

• To develop a green and efficient method for preparing vanadium-based materials with controlled heterovalent vanadium for ZIBs.
• To investigate the electrochemical performance of the synthesized material as a cathode in ZIBs.

Main Methods:

• A vanadium-supramolecular flower-shaped material (VSF) was synthesized in aqueous solution using NH4VO3 and hexamethylenetetramine.
• The optimal VSF material (PVSF-2/1) with a V5+/V4+ ratio of 2/1 was identified after presintering.
• Electrochemical performance was evaluated using coin cells and pouch cells, including specific capacity, rate capability, and cycling stability.

Main Results:

• The PVSF-2/1 cathode achieved a high specific capacity of 398.9 mAh g-1 at 0.2 A g-1, significantly outperforming pure VO2 and V2O5.
• The material exhibited excellent cycling stability, retaining 225 mAh g-1 at 5.0 A g-1 after 2000 cycles.
• Zn∥PVSF-2/1 pouch cells demonstrated a satisfactory specific capacity of 339 mAh g-1 at 0.2 A g-1.

Conclusions:

• The synthesized PVSF-2/1 material offers a promising cathode for high-performance ZIBs.
• The enhanced performance is attributed to the synergistic effects of heterovalent vanadium states, facilitating Zn2+ transport and providing abundant active sites.
• The study presents a viable strategy for designing advanced vanadium-based electrode materials for next-generation energy storage devices.