Integrated Network Cathodes by In Situ Phase Transition Break Diffusion Limitation for Zinc Ion Battery

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Aqueous zinc ion batteries (AZIBs) face limitations in capacity and development due to cathode material constraints.
• Vanadium-based materials suffer from poor conductivity, strong Zn²⁺ interactions, and narrow voltage windows.

Purpose of the Study:

• To engineer a novel cathode material for AZIBs by controlling phase transitions.
• To enhance the electrochemical performance, including capacity, rate capability, and cycling stability of AZIBs.

Main Methods:

• Modulating the voltage window to induce a phase transition from VO₂ to H_XV₂O₅.
• Fabricating an integrated network structure with low crystallinity and abundant active sites.
• Investigating the phase transition and energy storage mechanisms through electrochemical analysis.

Main Results:

• The engineered cathode exhibits high specific capacity (545 mAh g^-1 at 0.1 A g^-1) due to two-electron transfer.
• Impressive rate performance (185 mAh g^-1 at 20 A g^-1) and long-term cycling stability (179 mAh g^-1 after 15,000 cycles at 20 A g^-1) were achieved.
• Stable operation at low temperatures (-20 °C) and high energy/power densities (405 Wh kg^-1 at 74 W kg^-1) were demonstrated.

Conclusions:

• The integrated network structure and phase transition strategy effectively improve AZIB performance.
• The identified mechanisms provide insights for developing advanced cathode materials for AZIBs.
• Demonstrated potential for practical applications with pouch-type cells achieving 45.5 Wh kg^-1 energy density.