Cycling Rate-Induced Spatially-Resolved Heterogeneities in Commercial Cylindrical Li-Ion Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Analytical Chemistry

Background:

• Lithium-ion batteries are crucial for portable electronics and electric vehicles.
• Understanding degradation mechanisms in commercial batteries under operating conditions is essential for improving performance and lifespan.
• Current diagnostic tools often lack the spatiotemporal resolution to capture dynamic changes within real-world battery cells.

Purpose of the Study:

• To investigate commercial cylindrical lithium-ion batteries using synchrotron high-energy X-ray diffraction computed tomography.
• To map crystalline components and chemical species within the battery cross-section with high resolution.
• To identify and understand chemical heterogeneities and their origins during electrochemical cycling.

Main Methods:

• Synchrotron high-energy X-ray diffraction computed tomography was applied to cycled commercial Li-ion batteries.
• The Direct Least-Squares Reconstruction algorithm was used to address parallax issues.
• High spatiotemporal resolution imaging (20 × 20 × 3 µm³ voxels) was achieved within approximately 1 hour per scan.

Main Results:

• Accurate lattice parameter maps of the battery cathode were obtained.
• Chemical heterogeneities were observed at both the anode and cathode.
• These heterogeneities were correlated with uneven lithium and current distributions within the cells.

Conclusions:

• Synchrotron X-ray diffraction computed tomography is a powerful diagnostic tool for characterizing commercial batteries.
• The technique provides unique insights into real-world battery degradation mechanisms under operating conditions.
• Understanding heterogeneities is key to optimizing battery design and extending battery life.