Excess lithium storage and charge compensation in nanoscale Li 4+ x Ti 5 O 12

Lithium titanate spinel (Li 4 Ti 5 O 12 ; LTO) is a promising candidate for anodes in lithium-ion batteries due to its excellent cyclability and safety performance, and has been known as a ‘zero-strain’ material that allows reversible lithium insertion–deinsertion with little change in the lattice parameters. For a better understanding of lithium reaction mechanisms in this material, it has been of great interest to identify where lithium is inserted and how it migrates during charge and discharge, which is often difficult with x-ray and electron scattering techniques due to the low scattering power of lithium. In this study, we employed atomic-resolution annular bright-field imaging to directly image the lithium on interstitial sites in nanoscale LTO, and electron energy-loss spectroscopy to measure local lithium occupancy and electronic structure at different states of charge. During lithiation, charge compensation occurs primarily at O sites, rather ...

Feng Wang, Lijun Wu, Chao Ma, Dong Su, Yimei Zhu and Jason Graetz

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