Abstract
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 Li1.2 Ni0.2 Mn0.6 O2 is shown to have Li-rich Li2MO3 phase regions and Li-depleted Li(Ni0.5 Mn0.5)O2 regions. Cycled material has an overall loss of Li in addition to Ni-, Mn- and Li-rich regions. Spinel LiNi0.5 Mn1.5 O4 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.
Original language | English |
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Article number | 8014 |
Journal | Nature Communications |
Volume | 6 |
DOIs | |
State | Published - Aug 14 2015 |
Externally published | Yes |
Funding
The funding for the research described in this paper was from a Laboratory Directed Research and Development fund from the Chemical Imaging Initiative at Pacific Northwest National Laboratory (PNNL). PNNL is a multiprogram national laboratory operated by Battelle Memorial Institute, under Contract No. DE-AC05-76RLO1830 for the U.S. Department of Energy (DOE). RC would like to thank the Wiley Postdoctoral Fellowship for research funding. All the characterization was conducted in the William R. Wiley Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility sponsored by DOE’s Office of Biological and Environmental Research and located at PNNL.