Direct observation of active material interactions in flowable electrodes using X-ray tomography

Area of Science:

• Materials Science
• Electrochemistry
• Chemical Engineering

Background:

• Flowable electrodes are crucial for scalable deionization and energy storage, but their dynamic nature complicates structural analysis.
• Previous characterization of opaque, multiphase carbon suspensions relied on indirect electrochemical and rheological methods.

Purpose of the Study:

• To investigate the static structure and properties of electrochemically active biphasic flowable electrodes.
• To utilize synchrotron radiation X-ray tomographic microscopy (SRXTM) for detailed structural characterization.

Main Methods:

• Evaluation of mixed electronic and ionically conducting carbon-based suspensions.
• Application of SRXTM to resolve liquid and solid phases and reconstruct solid phase agglomeration.
• Analysis of cluster volumes and their impact on the overall material structure.

Main Results:

• SRXTM enabled visualization of carbon agglomeration in suspensions, with cluster volumes ranging from 10 μm³ to 10³ μm³.
• Low-loaded samples (5 wt%) showed limited electrically connected clusters (3% of volume).
• Higher loadings (10 wt% and 20 wt%) exhibited increased electrically connected carbon networks, occupying up to 85% of the imaged region.

Conclusions:

• SRXTM is a powerful technique for discerning the structural properties of biphasic flowable electrode systems.
• Discontinuities in carbon particle networks significantly decrease material utilization in low-loaded electrodes.
• Optimizing particle network formation is critical for enhancing performance in flowable electrode applications.