The positive electrodes in Ni-based rechargeable batteries are a complex composite consisting essentially of a
mixture of fine powders of
Ni and Ni(OH)2 that are pasted into a porous
support structure of metallic Ni foam. The performance of these electrodes is strongly dependent on the
microstructural characteristics of the constituent materials.
This FIB SE image shows a nickel metal foam strut after "stress-free" sectioning using the ion beam (inset). FIB
sectioning and imaging reveal grain structure and porosity difficult to observe using traditional techniques.
Grain orientation contrast can be very pronounced in FIB images. It is also possible, for many materials, to sputter
the surface in such a way as to preferentially etch grain boundaries (as is shown on the "sides" of the strut), or to
minimize grain boundary etching (as is shown on the "top" surface of the sectioned portion of the strut).