(298d) In-Situ, Non-Destructive, 3D Neutron Imaging of Li Plating/Stripping at Electrochemical Interfaces in Fast-Charged Li-Ion Batteries

Here, we present an in-situ, non-destructive 3D characterization of the morphological behavior and spatial heterogeneities of Li plating and stripping on graphite electrodes in full-cell LIBs using high-resolution neutron micro-computed tomography (µ-CT).^4-6 We performed neutron µCT⁷ (pixel size: ~ 5.74 µm; effective spatial resolution: ~10-15 µm) at the ICON beamline⁸ at the Swiss Spallation Neutron Source at the Paul Scherrer Institute. We imaged two batteries in charged and discharged states: (1) after 4 cycles of 1C charging and (2) after 6 cycles of 6C charging.

Our neutron imaging data shows that Li plates at and around the edge of graphite, indicating that the graphite edge and the areas around the edge are the most susceptible to Li plating. However, certain areas of the cells formed dead Li whereas others formed active Li. Specifically, we examine these spatial heterogeneities in four distinct regions: (1) near Cu current collector (CC), (2) in the middle of graphite electrode, (3) at the graphite-separator interface, and (4) in the separator. Our analysis reveals that Li near the Cu CC remained active, whereas Li near the interface and in the separator became dead at both charging rates: 1C and 6C. In addition, we observed a distinct 3D Li morphology at 6C vs. 1C. Tip-like Li deposits are seen mostly at 6C that became dead following battery discharging, suggesting a correlation between higher XFC-charging rate/cycling number and the increased formation of tip-like dead Li deposits. This work is significant because it deepens our 3D understanding of how Li plating leads to capacity fade, which is needed to realize XFC of LIBs for sustainable transportation.

References:

1. Liu et al. (2019). Challenges and opportunities towards fast-charging battery materials. Nature Energy, 1.
2. Liu et al. (2016). Understanding undesirable anode lithium plating issues in lithium-ion batteries. RSC advances, 6(91), 88683-88700.
3. Paul et al. (2021). A Review of Existing and Emerging Methods for Lithium Detection and Characterization in Li‐Ion and Li‐Metal Batteries. Advanced Energy Materials, 11(17), 2100372.
4. Yusuf, M. (2022). The In-situ Characterization of Fast-charging Degradation Modes in Li-ion Batteries Using High-resolution Neutron Imaging. The Electrochemical Society Interface, 31(4), 38.
5. Yusuf, M., Kaestner, A., Wied, M., LaManna, J. M., Vo, N. T., Dunlop, A. R., ... & Weker, J. N. (2024). Visualizing 3D Morphologies and Spatial Heterogeneities of Li after Fast-Charging via In-situ Neutron Tomography. [Submitted]
6. Yusuf, M., Kaestner, A., Zhang, Y., LaManna, J. M., Wied, M., Vo, N., ... & Weker, J. N. (2024, May). (Energy Technology Division Graduate Student Award sponsored by BioLogic) In-Situ, Non-Destructive, 3D Neutron Imaging of Lithium Plating Following Extreme Fast-Charging of Full-Cell Lithium-Ion Batteries. In 245th ECS Meeting (May 26-30, 2024). ECS.
7. Morgano et al. (2018). Unlocking high spatial resolution in neutron imaging through an add-on fibre optics taper. Optics Express, 26(2), 1809-1816.
8. Kaestner et al. (2011). The ICON beamline–A facility for cold neutron imaging at SINQ. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 659(1), 387-393.