Materials Science

Locating Lithium in Oxide Anodes

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Science  29 Jun 2012:
Vol. 336, Issue 6089, pp. 1621
DOI: 10.1126/science.336.6089.1621-b

Lithium titanate anodes are finding use in applications such as electric vehicles, where high charging and discharging rates are needed. Lu et al. have studied a model material, the spinel Li4Ti55O12, using a spherical-aberration–corrected scanning transmission electron microscopy technique. This method can locate lithium ions despite their inherent low contrast, given their low atomic number. The authors examined half-charged materials and could observe a sharp interface between the Li4Ti55O12 and Li7Ti55O12; the Ti and O columns are well aligned between these phases, but the Li ions shifted lattice sites, which is consistent with the lack of strain between these phases. They also show that the charge state of the Ti atoms is heterogeneous, and the presence of these local changes in valence is consistent with calculations that reveal strong lithium-electron interactions.

Adv. Mater. 24, 3233 (2012).

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