Electrochemically Induced Phase Transformation in Vanadium Oxide Boosts Zn-Ion Intercalation

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Vanadium oxides show promise as cathode materials for aqueous zinc-ion batteries due to their high storage capacity.
• Key limitations include poor electronic conductivity and slow zinc ion (Zn2+) diffusion, hindering practical application.
• Developing strategies to overcome these barriers is crucial for advancing battery technology.

Purpose of the Study:

• To propose and investigate an electrochemically induced phase transformation strategy for vanadium oxides in zinc-ion batteries.
• To enhance the electronic conductivity and Zn2+ diffusion kinetics of the cathode material.
• To improve the overall electrochemical performance, including capacity, rate capability, and cycling stability.

Main Methods:

• Electrochemical cycling to induce phase transformation from V6O13 to V5O12·6H2O.
• In situ X-ray diffraction to confirm the structural changes during charging.
• Theoretical calculations (DFT) to analyze migration energy barriers and band structures.
• Electrochemical performance testing (capacity, rate, cycling) of the transformed material.

Main Results:

• Complete phase transformation of V6O13 to layered V5O12·6H2O confirmed via in situ XRD.
• Theoretical calculations showed reduced Zn2+ migration energy barrier and facilitated charge storage kinetics.
• The transformed V5O12·6H2O exhibited a significantly reduced bandgap (0.0006 eV vs 0.5010 eV for V6O13).
• Achieved high capacity (609 mAh g-1 at 0.1 A g-1), superior rate performance (300 mAh g-1 at 20 A g-1), and excellent cycling stability (346 mAh g-1 at 5 A g-1 after 5000 cycles).

Conclusions:

• Electrochemical phase transformation is an effective strategy to enhance vanadium oxide cathode performance in aqueous zinc-ion batteries.
• The V5O12·6H2O phase offers improved electronic conductivity and faster Zn2+ diffusion, leading to superior electrochemical properties.
• This approach paves the way for developing high-performance and stable aqueous zinc-ion batteries.