Three‐Dimensional Microstructural Characterization of Lithium Manganese Oxide with Atom Probe Tomography

Abstract

The microstructure of the active material of Li‐ion batteries has a crucial influence on local ion‐transport processes but is not yet well characterized. Atom probe tomography (APT), a method combining sub‐nanometer spatial resolution with sub‐parts‐per‐thousand chemical resolution is well suited for 3 D microstructural characterization. Herein, the results of the characterization of lithium (nickel)manganese oxides [L(N)MO] with APT are presented. Structural and chemical defects of different dimensions such as the segregation of Na impurities to grain boundaries and the appearance of a Ni‐rich foreign phase are detected. Furthermore, a lamellar microstructure correlated to fluctuations in the local Li content was observed, and its influence on Li transport in the material is discussed. In defect‐free regions, the lattice planes of LMO are reconstructed for the first time, and the high spatial resolution of APT is revealed. Thus, the results demonstrate the potential of APT for the 3 D microstructural characterization of LMO.

In Situ Atom Probe Deintercalation of Lithium-Manganese-Oxide

“…Karahka et al (2015)). Nevertheless the data shows a uniform distribution of all elements and the spatial resolution is high enough to reveal lattice planes in the reconstruction (Maier et al, 2016). To measure eventual Li mobility at 30 K the automatic base voltage adjustment was stopped during a conventional atom probe analysis at a base voltage of 5.8 kV.…”

“…A ratio between 0.45 and 0.5 is typically found for not or just slightly deintercalated L x MO specimens (cf. Maier et al (2016)). The other ratios from 0.35 to 0.3 and from 0.15 to 0.1 do not fit to the equilibrium phases of Lithium-Manganese-Oxide reported in Ohzuku et al (1990).…”

Comparison of Different Synthesis Methods for LiNi0.5Mn1.5O4—Influence on Battery Cycling Performance, Degradation, and Aging

“…Laser‐assisted atom probe tomography measurements of the LNMO particles synthesized by the molten salt method were performed by Maier et al . This method has the ability to perform a 3 D characterization and reconstruction of LNMO samples on an atomic level in a range of approximately 100 nm 3 .…”

“…Laser-assisted atom probe tomography measurements of the LNMOp articles synthesized by the molten salt method were performed by Maier et al [64] This methodhas the ability to perform a3 Dc haracterizationa nd reconstructiono f LNMO samples on an atomic level in ar ange of approximately 100 nm 3 .T he evaluation of the local chemical composition revealed the presence of an impurity phase adjacent to the LNMO phase within as ingle particle.T he results suggest the presence of small amounts of aN i-rich and Li-free (NiMn) x O y impurity in the LNMOp owders synthesized by the molten salt method. As imilar Ni-rich impurity was observedr ecently by Boesenberg et al [65] by using X-ray absorption near-edge spectroscopy (XANES) measurements.…”

“…However, Boesenberg et al claimedt hat the Ni-rich impurity phase evolved during cycling instead of during synthesis, which leads to an inactive impurity phase.Acomprehensive study on the characterization method and the analyzed impurity phase is given in Ref. [64].…”