Surface- and interlayer-modified ammonium vanadate cathode for high-performance aqueous Zn-ion batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Vanadium-based compounds face challenges like poor conductivity and structural instability in aqueous zinc-ion batteries.
• Developing stable and efficient cathode materials is crucial for advancing rechargeable aqueous zinc-ion battery technology.

Purpose of the Study:

• To improve the electrochemical performance of ammonium vanadates (NH4V4O10) for aqueous zinc-ion batteries.
• To investigate the effect of conductive polymer (polypyrrole, PPy) coating and pre-intercalation on zinc ion storage.

Main Methods:

• Synthesized PPy-coated/pre-intercalated ammonium vanadates (PPy-NVO) nanobelts.
• Utilized electrochemical testing to evaluate capacity, rate performance, and cycling stability.
• Employed ex situ characterization techniques to analyze the storage mechanism.

Main Results:

• The PPy-NVO electrode exhibited a high discharge capacity of 455 mAh g⁻¹ at 0.1 A g⁻¹.
• The material maintained 89% of its initial capacity after 2500 cycles at 4 A g⁻¹.
• PPy modification enhanced ion diffusion and electronic conductivity, suppressing dissolution.

Conclusions:

• PPy coating and pre-intercalation effectively stabilize ammonium vanadates and improve zinc ion storage.
• The PPy-NVO cathode demonstrates significant potential for high-performance aqueous zinc-ion batteries.
• The study confirms a reversible Zn²⁺ insertion/extraction mechanism in the PPy-NVO cathode.