inside Energy Materials

Mapping structural changes as batteries charge and discharge by 3D X-Ray Microscopy and Digital Volume Correlation.

Recent advances in high-resolution 3D X-ray computed tomography (CT) allow detailed, non-destructive 3D structural mapping of a complete lithium ion battery. By repeatedly acquiring 3D images (time lapse CT imaging) these investigations of material microstructure are extended into the fourth dimension (time) to study the structural changes of the device as it charges and discharges.

Indeed, the electrode expands and contracts as it discharges and charges. By digital volume correlation (DVC) of successive 3D images the dimensional changes taking place during charge cycling are quantified at the electrode level and at the Mn2O4 particle scale.

After battery discharging, the extent of lithiation of the manganese (III/IV) oxide grains in the electrode is found to be a function of the distance from the battery terminal with grains closest to the electrode/current collector interface having the greatest expansion (≈30%) and grains furthest from the current collector and closest to the counter electrode showing negligible dilation. This is helping us to better understand the damage that accumulates as batteries care charged and discharged many times leading to better battery lifetimes.

See:

Eastwood DS, Yufit V, Gelb J, et al., (2014), Lithiation- Induced Dilation Mapping in a Lithium- Ion Battery Electrode by 3D X- Ray Microscopy and Digital Volume Correlation, Advanced Energy Materials, Vol: 4, ISSN:1614-6832

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