Pre-Intercalation of Metal Ions into Ammonium Vanadate Nanostructures toward Advanced Zinc Ion Batteries

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Aqueous zinc ion batteries (AZIBs) featuring low cost and high safety are attracting considerable interest. More recently, ammonium vanadate, characterized by its high specific capacity, is regarded as a promising cathode material for AZIBs. However, their unstable layered structures and sluggish reaction kinetics limit their further development. To overcome these limitations, metal ions (Na + and Zn 2+ ) are pre-intercalated into ammonium vanadate to modify the interlayer spacing and enhance charge transfer kinetics. Additionally, the impact of different pre-intercalated ions on the structure and properties of ammonium vanadate is systematically investigated. Furthermore, we successfully synthesized ammonium vanadate cathode materials (Na 0.13 (NH 4 ) 0.48 V 2 O 5 ·0.6H 2 O, Na 0.13 -NVO) featuring stable nanostructures by optimizing the pre-embedded Na + content. In this case, pre-intercalated sodium ions could expand the layer spacing of ammonium vanadate (9.14 Å), reduce the electrostatic interaction of Zn 2+ with the V–O framework, and boost the Zn 2+ diffusion rate. Benefitting from these strengths, the Na 0.13 -NVO electrode exhibits a specific capacity of 365.4 mAh g –1 at 0.5 A g –1, along with a good cycling stability of 98.1% capacity retention over 2000 cycles at 5 A g –1 . This work supplies further insights into designing ammonium vanadate with pre-embedded metal ions and aids the development of high-performance AZIB cathodes.