Operando crystal-amorphous transformation cathode for enhanced zinc storage

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Aqueous zinc-ion batteries (AZIBs) offer safety, eco-friendliness, and low cost but require advanced cathode materials.
• Limited high-performance cathode options and unclear zinc storage mechanisms hinder AZIB development.

Purpose of the Study:

• To investigate the operando crystal-amorphous transformation of tunnel-type VOOH as a cathode material for AZIBs.
• To elucidate the zinc storage mechanism enabled by this transformation.
• To demonstrate the electrochemical performance of the resulting amorphous V2O5 cathode.

Main Methods:

• In-situ X-ray diffraction (XRD) to observe structural changes during charging.
• X-ray photoelectron spectroscopy (XPS) to analyze element valence evolution.
• Transmission electron microscopy (TEM) to study lattice structure modifications.

Main Results:

• Confirmed an operando crystal-amorphous transformation of VOOH to amorphous V2O5 during the initial charge cycle.
• Achieved a high specific capacity of ~350.7 mAh g⁻¹ with amorphous V2O5.
• Demonstrated excellent rate capability (151.2 mAh g⁻¹ at 6.4 A g⁻¹) and high energy/power densities (137 Wh kg⁻¹ at 6831 W kg⁻¹).

Conclusions:

• The operando electrochemical crystal-amorphous transformation is a viable strategy for developing high-performance AZIB cathodes.
• Amorphous V2O5 derived from VOOH shows significant potential for enhanced zinc storage.
• This approach offers a promising pathway for advancing AZIB technology.