Notice: Please notice that it is normal to observe NiO peaks in the nickel foam in XRD data. It is really difficult to avoid the oxidation of the nickel.
How to clean the Nickel Foam for Battery Cathode Substrate.
Nickel foam (about 3.3 cm x 1 cm) was carefully cleaned with the concentrated HCl solution (37 wt.%) in an ultrasound bath for 5 min in order to remove the surface oxide layer. And then deionized water and absolute ethanol was used for 5 min each to ensure the surface of the Ni foam was well cleaned.