Imaging the 4D Chemical Heterogeneity of Single V₂O₅ Particles During Charging/Discharging Processes

Area of Science:

• Materials Science
• Electrochemistry
• Advanced Imaging Techniques

Background:

• Microparticle cathode materials are crucial for secondary batteries, but understanding their dynamic chemical heterogeneities is difficult.
• Vanadium pentoxide (V₂O₅) is a promising cathode material for zinc-ion batteries, yet its performance limitations remain unclear.

Purpose of the Study:

• To develop and apply a novel in situ imaging approach for visualizing the 4D chemical heterogeneity of single V₂O₅ particles during battery cycling.
• To elucidate the root cause of poor performance in V₂O₅-based zinc-ion batteries.

Main Methods:

• Development of a fluorescence/scattering dual-mode spinning disk confocal microscopy technique for in situ imaging.
• Utilizing dual-mode imaging to track valence state changes of vanadium ions with high spatiotemporal resolution.
• Correlative analysis using Raman, UV-Vis spectroscopy, and electrochemical impedance spectroscopy (EIS).

Main Results:

• The dual-mode microscopy revealed distinct scattering intensity differences at the electric contact points of V₂O₅ particles during discharge.
• Correlative analyses indicated the precipitation of V³⁺ species at the electrode's bottom interface, increasing electron transfer resistance.
• A coordination strategy using ethylene diamine tetraacetic acid (EDTA) effectively inhibited V³⁺ precipitation.

Conclusions:

• V³⁺ precipitation at the electrode interface significantly compromises the performance of V₂O₅ cathodes in zinc-ion batteries.
• The developed in situ imaging approach provides critical insights into dynamic chemical heterogeneity.
• The findings enable the rational design of high-performance battery materials by addressing interfacial precipitation issues.