The distribution of cations in Li-ion battery cathodes as a function of cycling is a pivotal characteristic of battery performance. The transition metal cation distribution has been shown to affect cathode performance; however, Li is notoriously challenging to characterize with typical imaging techniques. Here laser-assisted atom probe tomography (APT) is used to map the three-dimensional distribution of Li at a sub-nanometre spatial resolution and correlate it with the distribution of the transition metal cations (M) and the oxygen. As-fabricated layered Li<inf>1.2</inf> Ni<inf>0.2</inf> Mn<inf>0.6</inf> O<inf>2</inf> is shown to have Li-rich Li<inf>2</inf>MO<inf>3</inf> phase regions and Li-depleted Li(Ni<inf>0.5</inf> Mn<inf>0.5</inf>)O<inf>2</inf> regions. Cycled material has an overall loss of Li in addition to Ni-, Mn- and Li-rich regions. Spinel LiNi<inf>0.5</inf> Mn<inf>1.5</inf> O<inf>4</inf> is shown to have a uniform distribution of all cations. APT results were compared to energy dispersive spectroscopy mapping with a scanning transmission electron microscope to confirm the transition metal cation distribution.
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)
- Physics and Astronomy(all)