FIB Sectioning & Imaging of Nickel Metal Foam Used in Rechargeable Batteries
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Figure 1:This FIB SE image shows a nickel metal foam strut after "stress-free" sectioning using the ion beam (inset)
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 that is 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).
