Short-Range-Ordered VO₆ Oxides with Oxygen Vacancy-Free Frameworks Boost Zinc-Ion Battery Performance

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Vanadium-based cathodes are promising for aqueous zinc-ion batteries (AZIBs) due to high theoretical capacity.
• Challenges remain in developing high-performance cathodes and effective design principles for AZIBs.
• Structural building blocks in vanadium oxides significantly influence battery capacity and stability.

Purpose of the Study:

• To investigate the role of structural building blocks ([VO4], [VO5], [VO6]) in vanadium-based oxides for AZIBs.
• To understand how oxygen vacancies affect the stability of vanadium oxide cathodes.
• To design and synthesize an optimized vanadium oxide cathode for enhanced AZIB performance.

Main Methods:

• Analysis of the contributions of [VO4] tetrahedra, [VO5] square pyramids, and [VO6] octahedra to cathode performance.
• Investigating the impact of oxygen vacancies on the stability of [VO6] building blocks.
• Synthesis of amorphous vanadium oxide (ZVO-O_v-free) with oxygen vacancy-free [VO6] octahedra.

Main Results:

• [VO6] octahedra demonstrate superior capacity and stability compared to other building blocks in vanadium oxides.
• Oxygen vacancies destabilize [VO6] octahedra by increasing exposed vanadium sites.
• The synthesized ZVO-O_v-free cathode achieved a high specific capacity (483 mAh g⁻¹ at 0.3 A g⁻¹) and excellent capacity retention (94% after 150 cycles).

Conclusions:

• Oxygen vacancy-free [VO6] octahedra arranged in short-range-ordered chains maximize active vanadium site utilization.
• Rational design at atomic and framework levels is crucial for developing high-performance vanadium-based oxides.
• The findings pave the way for the practical application of AZIBs technology.