Distorting Local Structures to Modulate Ligand Fields in Vanadium Oxide for High-Performance Aqueous Zinc-Ion...

Area of Science:

• Materials Science
• Electrochemistry
• Inorganic Chemistry

Background:

• Layered hydrate vanadates are promising cathode materials for aqueous zinc-ion batteries (AZIBs).
• Preinsertion of intercalants enhances kinetics and stabilizes structures, but the relationship between intercalant type and property enhancement needs clarification.

Purpose of the Study:

• To investigate the structural distortions and ligand field changes induced by benzyltrimethylammonium (BTA+) intercalation in hydrate vanadium pentoxide (VOH).
• To elucidate the relationship between local structural modifications and electrochemical performance in AZIBs.

Main Methods:

• Synchrotron X-ray pair distribution function (PDF) and X-ray absorption fine structure (XAFS) were employed to study local coordination and electronic structure.
• Electrochemical testing was performed to evaluate the performance of the modified cathode material.

Main Results:

• BTA+ intercalation induces octahedral distortion and alters the ligand field, lowering the energy of the lowest unoccupied orbitals (e*).
• This leads to an increased electrochemical potential and enhanced ion diffusion.
• The BTA+-modified cathode exhibits a specific capacity of 408 mAh/g at 0.5 A/g and 95% capacity retention after 3000 cycles at 8 A/g.

Conclusions:

• Preintercalation of BTA+ cations effectively modifies the local structure and electronic properties of hydrate vanadates.
• The resulting structural distortions and improved ion diffusion significantly enhance the electrochemical performance of AZIBs, demonstrating a promising strategy for advanced battery materials.