Nature https://doi.org/gfkfj3 (2018)

Lithium is typically used in energy-storage devices that exhibit a high energy density, or a low self-discharge rate. Improving the performance of lithium batteries requires a detailed knowledge of the in situ atomic structure of these devices under working conditions — a notoriously difficult task for such light elements. Now, Matthias Kühne and colleagues have found a way to visualize lithium atoms sandwiched within bilayer graphene connected to an electrochemical cell — revealing ordering on an atomic level that has so far gone unseen.

Kühne and colleagues used a contrast-enhanced transmission electron microscope with sub-ångström resolution to image the device, thus allowing controlled time-resolved lithiation by voltage tuning. They observed a crowded multilayer ordering of lithium between the graphene sheets, which may be useful for designing batteries with enhanced storage capacity.