John Cowley and his group at Arizona State University pioneered the
use of transmission electron microscopy (TEM) for high-resolution
imaging. Three decades ago they achieved images showing the crystal
unit cell content at better than 4 Å resolution. Over the years,
this achievement has inspired improvements in resolution that have
enabled researchers to pinpoint the positions of heavy atom columns
within the cell. More recently, this ability has been extended to light
atoms as resolution has improved. Sub-Ångstrom resolution has
enabled researchers to image the columns of light atoms (carbon,
oxygen, and nitrogen) that are present in many complex structures. By
using sub-Ångstrom focal-series reconstruction of the specimen
exit surface wave to image columns of cobalt, oxygen, and lithium atoms
in a transition metal oxide structure commonly used as positive
electrodes in lithium rechargeable batteries, we show that the range of
detectable light atoms extends to lithium. HRTEM at sub-Ångstrom
resolution will provide the essential role of experimental verification
for the emergent nanotech revolution. Our results foreshadow those to
be expected from next-generation TEMs with CS-corrected
lenses and monochromated electron beams.