July 31, 2018 | News Brief | Columbia University researchers announced yesterday that they have used stimulated Raman scattering (SRS) microscopy, a technique widely used in biomedical studies, to explore the mechanism behind dendrite growth in lithium batteries and, in so doing, have become the first team of material scientists to directly observe ion transport in electrolytes. They discovered a lithium deposition process that corresponds to three stages: no depletion, partial depletion (a previously unknown stage), and full depletion of lithium ions. They also found a feedback mechanism between lithium dendrite growth and heterogeneity of local ionic concentration that can be suppressed by artificial solid electrolyte interphase in the second and third stages. The paper is published online in Nature Communications (https://doi.org/10.1038/s41467-018-05289-z).
Imaging ion transport in a liquid electrolyte is highly challenging, the paper’s authors write. But they found that SRS microscopy’s two spatially- and temporally-synchronized picosecond laser pulse trains offer a desirable combination of high sensitivity, fast imaging speed, fine spatial resolution, label-free nature, and intrinsic 3D optical sectioning.
“We show that SRS imaging can quantitatively capture the fast evolution of the ion concentration at a Li surface and how the concentration is related to the growth of Li dendrites,” the authors write. “Our imaging results revealed the Li electrodeposition has three stages. In addition to the slow growth of mossy Li in the initial stage and rapid dendritic growth in the final stage upon full depletion of Li+, a previously unknown intermediate stage corresponding to the partial depletion of Li+ was observed in a spatially heterogeneous manner.”
Read the paper in Nature Communications.
Read interviews with the authors on the work’s significance and next steps at Columbia University.