Measuring Dynamic Gradients in Drying Battery Electrode Coatings via Microscale Resistivity

Area of Science:

• Materials Science
• Electrochemistry
• Battery Technology

Background:

• In situ techniques for studying lithium-ion battery (LIB) electrode microstructural evolution are often costly or inaccessible.
• Previous research suggests superior LIB performance with electrodes coated at high shear rates, potentially due to differences in carbon connectivity.
• Understanding the dynamic microstructural changes during electrode drying is crucial for optimizing battery performance.

Purpose of the Study:

• To demonstrate a simple, cost-effective four-line probe for measuring dynamic electrode microstructures in situ.
• To investigate the effects of coating shear rate on the transient and final microstructure of LIB electrodes during drying.
• To elucidate the drying mechanisms influenced by shear rate and their impact on electrode properties.

Main Methods:

• Utilized a cost-effective four-line probe device to measure electrode resistance at varying penetration depths.
• Applied heuristic drying models to interpret resistivity data and propose drying mechanisms.
• Validated findings using electrochemical fluorescence microscopy (EFM) and energy dispersive spectroscopy (EDS) imaging of dried electrodes.

Main Results:

• Electrode resistance measurements showed distinct dynamic microstructural differences between high and low shear rates, indicating varied drying mechanisms.
• Observed aggregation and sedimentation of carbon particles at early drying stages for low shear rates.
• Identified the formation of a carbon-rich top layer during drying for both shear rates, confirmed by EFM and EDS.

Conclusions:

• The low-cost, in situ four-line probe method effectively captures shear-dependent microstructural evolution during composite electrode drying.
• Shear rate significantly influences drying mechanisms, leading to different microstructures and impacting battery performance.
• This study provides a comprehensive understanding of shear effects on electrode development, crucial for advanced battery manufacturing.