Quantification and chemical fluctuation in NMC Li-ion battery cathode materials analyzed using APT

The use of atom probe tomography (APT) in renewable energy research has increased dramatically in the last decade. The technique offers a unique prospect for the investigation of Li-containing materials in energy storage applications. As a proof of principle, this work demonstrates the capability of APT in chemical quantification and microstructure analysis by studying two types of Ni–Mn–Co materials. Strategies for preparing APT specimens from cathode particles are outlined. The results provide insight into compositional homogeneity among the primary and the secondary particles that make up the cathode. Additionally, nanosized features characterized by Li enrichment, Ni/Mn partitioning, and dopant-decorated particle boundaries are observed and quantitatively analyzed using APT.

Atom probe tomography analysis is ideal for examining fine-scale features in NMC cathode materials. While the majority of the specimens exhibit a homogeneous distribution of the constituent element as shown in (a), some data reveals distinct Li-enriched features. In (b), besides the non-uniform distribution for Ni and Mn, planar features displaying a significantly higher Li concentration are presented in purple. In (c), dopant (aluminum) decorated boundaries between primary particles are subjected to quantitative analysis using APT