In SituAtom Probe Deintercalation of Lithium-Manganese-Oxide

Abstract

Atom probe tomography is routinely used for the characterization of materials microstructures, usually assuming that the microstructure is unaltered by the analysis. When analyzing ionic conductors, however, gradients in the chemical potential and the electric field penetrating dielectric atom probe specimens can cause significant ionic mobility. Although ionic mobility is undesirable when aiming for materials characterization, it offers a strategy to manipulate materials directly in situ in the atom probe. Here, we present experimental results on the analysis of the ionic conductor lithium-manganese-oxide with different atom probe techniques. We demonstrate that, at a temperature of 30 K, characterization of the materials microstructure is possible without measurable Li mobility. Also, we show that at 298 K the material can be deintercalated, in situ in the atom probe, without changing the manganese-oxide host structure. Combining in situ atom probe deintercalation and subsequent conventional characterization, we demonstrate a new methodological approach to study ionic conductors even in early stages of deintercalation.

Tracking the Diffusion-Controlled Lithiation Reaction of LiMn2O4 by In Situ TEM

“…Laser-assisted atom probe tomography (APT) is used to look more carefully for any possible variations in composition within the twinned structure. We use here the same APT method that has been successfully applied previously to investigate lithium distributions in LMO by Pfeiffer and Maier et al , In this case, a fine needle was cut directly from the in situ TEM lithiated specimen in Figure by using FIB and then analyzed with laser-assisted APT (Figure ). The Li to Mn ratio is roughly double of what has been found in previous APT reconstructions of LiMn 2 O 4 , further confirming that the in situ TEM lithiated material is the Li 2 Mn 2 O 4 phase.…”

“…31 The analysis temperature of 30 K immobilizes the lithium and allows determination of lithium concentrations at and across defects. 30 ASSOCIATED CONTENT Video of in-situ experiment referred to in Figure 1 SI-Figure 5 shows the local Li/Mn ratio obtained from an APT reconstruction (Figure 5)…”

“…A sketch of the mirror plane and the two twin variants, excluding any distortions at the interface, provides a possible visualization of the twinned crystallographic structure (Figure Laser-assisted atom probe tomography (APT) is used to look more carefully for any possible variations in composition within the twinned structure. We use here the same APT method that has been successfully applied previously to investigate lithium distributions in LMO by Pfeiffer and Maier, et al 30,31 In this case, a fine needle was cut directly from the in-situ TEM lithiated specimen in Figure 4 using FIB, and then analysed with laser-assisted APT (Figure 5). 32 This is also multiple orders of magnitude smaller than the surface diffusion coefficient of lithium on graphite ( = 5 • 10 cm /s) 33 , which allows us to conclude that the reaction front is controlled by lithium diffusion in the twinned single crystal Li 2 Mn 2 O 4 phase.…”

Atom probe analysis of electrode materials for Li-ion batteries: challenges and ways forward

“…[18][19][20] In the case of Li-containing materials, the intense electric eld necessary to trigger the eld evaporation of surface atoms to enable their analysis can also drive atomic migration during the analysis itself. 21 This in situ delithiation process 22 can make the data unreliable. Species-specic losses associated with the dissociation of molecular ions have been also evidenced in these materials, thereby lowering the spatial resolution and elemental sensitivity.…”

Investigation of Lithium Manganese Oxides Using High-Dimensional Neural Networks

“…Various experimental techniques like, e.g., x-ray diffraction (XRD), transmission electron microscopy, atom probe tomography, x-ray absorption spectroscopy, electron energy loss spectroscopy, and cyclic voltammetry [19,20,31,52,[66][67][68] have provided detailed insights into the structure and properties of Li x Mn 2 O 4 as reported above. Theoretical investigations can provide complementary information, for instance, about individual atomic environments and the dynamics at the atomic scale.…”