The cathode materials in lithium-ion batteries (LIBs)
require improvements
to address issues such as surface degradation, short-circuiting, and
the formation of dendrites. One such method for addressing these issues
is using surface coatings. Coatings can be sought to improve the durability
of cathode materials, but the characterization of the uniformity and
stability of the coating is important to assess the performance and
lifetime of these materials. For microscale particles, there are,
however, challenges associated with characterizing their surface modifications
by transmission electron microscopy (TEM) techniques due to the size
of these particles. Often, techniques such as focused ion beam (FIB)-assisted
lift-out can be used to prepare thin cross sections to enable TEM
analysis, but these techniques are very time-consuming and have a
relatively low throughput. The work outlined herein demonstrates a
FIB technique with direct support of microscale cathode materials
on a TEM grid that increases sample throughput and reduces the processing
time by 60–80% (i.e., from >5 to ∼1.5 h). The demonstrated
workflow incorporates an air–liquid particle assembly followed
by direct particle transfer to a TEM grid, FIB milling, and subsequent
TEM analysis, which was illustrated with lithium nickel cobalt aluminum
oxide particles and lithium manganese nickel oxide particles. These
TEM analyses included mapping the elemental composition of cross sections
of the microscale particles using energy-dispersive X-ray spectroscopy.
The methods developed in this study can be extended to high-throughput
characterization of additional LIB cathode materials (e.g., new compositions,
coating, end-of-life studies), as well as to other microparticles
and their coatings as prepared for a variety of applications.