Phase and Orientation Mapping in Lithium-Ion Battery Electrodes

Complex Structures Behind Battery Failure

NASICON-type anode particles exhibit different ionic transport behavior and often contain multiple Ti-bearing phases that are indistinguishable using EDS alone.

Meanwhile, Ni-rich cathodes like NCM811 offer high energy density but are prone to Li/Ni disorder, microcrack formation, and phase inhomogeneity during cycling—especially at high states of charge.

Traditional imaging or spectroscopy cannot resolve how these phases are distributed or oriented, nor how they evolve under electrochemical cycling. 4D-STEM bridges this gap with localized, crystallographic sensitivity.

4D-STEM and EDS mapping of cycled cathode and anode samples

Anode samples of LiTi₂(PO₄)₃ containing TiO₂ inclusions were scanned at 50 pA with 14 mrad precession and 2 mrad convergence. Templates for multiple Ti-bearing phases enabled orientation and phase differentiation. EDS maps for Ti, O, and P supported structural interpretation at the nanoscale.

 Battery materials from disassembled 811|G and 811|GSO pouch cells were analyzed via 4D-STEM on the Tescan TENSOR. Cathode scans were performed at 200 pA, 0.8° precession, and 1.5 mrad convergence, with strain and phase mapping overlaid on HAADF images.

Structural contrast and phase clarity across cathode and anode studies

In the NASICON anode, TiO₂ inclusions were detected at grain edges and identified as small (5–10 nm) crystalline grains in different orientations, a distinction not accessible via traditional EDS. Orientation maps showed local texture in the matrix, suggesting anisotropic transport.

In NCM811, 4D-STEM revealed surface spinel formation and localized strain in the 811|G sample, while 811|GSO showed more uniform phase behavior and fewer defects, consistent with improved cycling stability.

Together, these results highlight the value of TENSOR’s multimodal workflow for resolving phase behavior, strain, and orientation in battery degradation studies.