Amorphous electroless Ni-B coatings were deposited on steel substrates with different
surface morphologies and B contents (6.5–8.64 wt.%) that could be changed by altering
the temperature and the composition of the baths. The supercapacitive behavior of
the coatings was evaluated by cyclic voltammetry and galvanostatic charge–discharge
measurements, and it was found that Ni-B coatings had higher capacitance than pure
electroless Ni or the bulk Ni plate. A close relationship was identified between the
microstructure, the B content, and the capacitive behavior of the coatings. The presence
of the B alloying element had the most significant effect in determining the capacitance,
while the surface area and particle size also contributed to its increase. A surface-specific
capacity of 31 mF/cm2 was achieved by the coating containing the highest B content
and largest AFM surface area. Furthermore, it was revealed that the particle size
of the deposits was determined by the combined effect of the bath temperature and
the B content under the applied experimental conditions. The obtained results indicate
that Ni-B coatings are promising candidates for supercapacitive applications.
