  The worldwide developments of electric vehicles, as well as large-scale or
grid-scale energy storage to compensate the intermittent nature of renewable
energy generation has generated a surge of interest in battery technology.
Understanding the factors controlling battery capacity and, critically, their
degradation mechanisms to ensure long-term, sustainable and safe operation
requires detailed knowledge of their microstructure and chemistry, and their
evolution under operating conditions, on the nanoscale. Atom probe tomography
(APT) provides compositional mapping of materials in three-dimensions with
sub-nanometre resolution, and is poised to play a key role in battery research.
However, APT is underpinned by an intense electric-field that can drive lithium
migration, and many battery materials are reactive oxides, requiring careful
handling and sample transfer. Here, we report on the analysis of both anode and
cathode materials, and show that electric-field driven migration can be
suppressed by using shielding by embedding powder particles in a metallic
matrix or by using a thin conducting surface layer. We demonstrate that for a
typical cathode material, cryogenic specimen preparation and transport under
ultra-high vacuum leads to major delithiation of the specimen during the
analysis. In contrast, transport of specimens through air enables analysis of
the material. Finally, we discuss the possible physical underpinnings and
discuss ways forward to enable shield of the electric field, which helps
address the challenges inherent to the APT analysis of battery materials.
