H⁺-empowered potassium vanadate cathode: An electron/ion/interface trifecta for high-performance zinc-ion batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Aqueous zinc-ion batteries (AZIBs) offer a low-cost, high-performance solution for large-scale energy storage.
• Layered vanadium-based materials are attractive AZIB cathodes due to high capacity and versatile energy storage.
• Understanding ion substitution effects is crucial for optimizing cathode performance.

Purpose of the Study:

• To synthesize potassium vanadate (KVO) and hydrogen-incorporated KVO (HKVO) materials.
• To investigate the influence of H+ incorporation on structural characteristics and electrochemical performance in AZIBs.
• To elucidate the mechanisms behind performance enhancement via theoretical calculations and experimental analysis.

Main Methods:

• Synthesis of KVO and HKVO materials.
• Electrochemical characterization including capacity, cycling stability, and rate capability tests.
• Density Functional Theory (DFT) calculations to analyze structural, electronic, and ion transport properties.

Main Results:

• HKVO exhibits enhanced electrical conductivity and ion transport kinetics compared to KVO due to H+ substitution.
• DFT calculations reveal narrowed band-gap, bond-length distortion, and expanded ion channels in HKVO.
• HKVO demonstrates improved electrolyte wettability and enhanced interfacial contact, leading to superior electrochemical performance: 669.4 mAh g⁻¹ at 0.1 A g⁻¹ and 93.2% capacity retention after 5000 cycles at 5 A g⁻¹.

Conclusions:

• Incorporation of H+ into the vanadate structure significantly enhances AZIB cathode performance.
• The study demonstrates the potential of H+ to regulate cathode structure, improve interfacial properties, and boost ionic kinetics.
• HKVO presents a promising cathode material for high-performance aqueous zinc-ion batteries.