I-016

Sandrine Lyonnard

sandrine.lyonnard@cea.fr

CEA-IRIG, France

Probing ion concentrations in batteries at multiple scales by synchrotron and neutron techniques

Ion concentration heterogeneities in rechargeable batteries constitute one major cause of heterogeneous function and degradation, potentially leading to defective areas and cell failure. The local concentration of lithium ions may vary both in-plane and through-plane in the electrodes and the electrolyte, and these heterogeneities develop across multiple scales (from particle scale to component or even device level). Local changes in state-of-charge (SoC) or gradients develop due to materials properties (e.g. electrochemical potential shape) or cell conditions (fast charging, overpotential, relaxations, long-term cycling, etc.). Experimentally, probing the ion inventory in a working cell is challenging, and requires operando tools enabling fast scanning of the cell to resolve local ion concentrations as well as their evolutions during charging/discharging. Scanning synchrotron microbeam techniques allow to map Li-ion batteries with graphite and silicon-graphite anodes, and acquire 2D ion concentration maps within minutes and with micrometer resolution. The quantification of lithium content as well as its localization enable to reveal charge dynamics during relaxation periods [1] or to establish the link between cycling rates or aging and the extent of lithiation heterogeneities in the depth of the electrode [2,3]. Also, multimodal approaches combining different types of techniques  as neutron imaging, x-ray tomography, sensing, etc., are used to access 3D reaction heterogeneities in industry-grade cells [4] or local reaction kinetics in sensor-equipped industrial cells [5]. All these methods, combined with chemical sensitives approaches and/or modelling, are powerful to determine the underlying mechanisms governing ion transport in complex microstructured materials used in electrochemical storage devices.

[1] C. Berhaut et al., Charge Dynamics Induced by Lithiation Heterogeneity in Silicon-Graphite Composite Anodes. Adv. Energy Mater. 2023, 13, 2301874.

[2] S. Tardif et al., Combining operando X-ray experiments and modelling to understand the heterogeneous lithiation of graphite electrodes. J. Mat. Chem. A, 2021, 9, 4281.

[3] G. Oney et al., Spatiotemporal Analysis of Graphite Electrode Aging Through X-rays, 2025, https://doi.org/10.48550/arXiv.2503.06113.

[4] Lübke et al., The origins of critical deformations in cylindrical silicon based Li-ion batteries. Energy. Env. Sci. 2024, 17, 5048-5059. 

[5] A. Olgo et al. The Local Impact of Sensors on a Commercial Li-ion Battery Pouch Cell Graphite Electrode Lithiation Mechanism. Nature Communication, 2024, 1 5:10258.