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Quantifying Transport, Geometrical, and Morphological Parameters in Li-Ion Cathode Phases Using X‑ray Microtomography
journal contribution
posted on 2019-05-08, 00:00 authored by Thushananth Rajendra, Aashutosh N. Mistry, Prehit Patel, Logan J. Ausderau, Xianghui Xiao, Partha P. Mukherjee, George J. NelsonThe
charge/discharge capabilities of Li-ion cathodes are influenced
by the meso-scale geometry, transport properties, and morphological
parameters of the constituent phases in the cathode: active material,
binder, conductive additive, and pore. Electrode processing influences
the structure and attendant properties of these constituents. Thus,
performance of the battery can be enhanced by correlating various
electrode processing techniques with the charge/discharge behavior
in the lithium-ion cathodes. X-ray microtomography was used to image
samples obtained from pristine Li(Ni1/3Mn1/3Co1/3)O2 (NMC) cathodes subjected to distinct
processing approaches. Two sample preparation approaches were applied
to the samples prior to microtomography. Casting the samples in epoxy
yielded only the cathode active material domain. Encapsulating the
sample with Kapton tape yielded phase contrast data that permitted
segmentation of the active material and combined carbon/binder and
pore regions. Geometrical and morphological details of the active
material and the secondary phases were characterized and compared
between the varied processing approaches. Calendered and ball-milled
samples exhibited distinct differences in both geometry and morphology.
Drying modes demonstrated variation in the distribution of the secondary
and pore phases. Applying phase contrast capabilities, the processing–morphology
relationship can be better understood to enhance overall battery performance
across multiple scales.