1Calculated from CDC data (applied current: 1A)
Furthermore, looking at the discharge current vs. specific capacitance
plot (Fig. 6(d)), the capacitance drop due to the current increase in
foamed electrodes is slightly less than those in rGO and rGO:CB. This
may be due to the incompatibility of the pore size of the rGO and rGO:CB
materials and the ion diameters in the electrolyte.
Also, when considering the
decrease in capacitance due to the increase in current, it is clear that
the curve of NirGO3 is more linear, and there is less drop in the rGO:CB
and NirGO3, in which NirGO3 shows higher performance than the other
electrodes. This is because although CB increases the surface area of
the electrode material, it causes an irregularity in the pore
structure due to its structure. The accumulation and release of ions in
the electrolyte decrease at high currents. In addition, specific energy
and power values of the electrodes at different currents were
determined from CDC graphs to obtain the Ragone Plot. The Ragone plot,
which has power density and energy density axes, helps to illustrate the
electrochemical performance of the device. In studies conducted at 5
different current values between 1-5 A g-1, the
energy density values of standard electrodes decrease dramatically with
the increase of current density, although their power densities
increase. However, the decrease of energy density in foamed electrodes
is less than those of reference electrodes. It was observed that the
foamed electrodes retain their specific energy more than those of rGO
and rGO:CB at high specific power values (Fig. 6(e)). As mentioned
above, the ion paths are short and favourable for the diffusion of ions
throughout the foam-structured Ni-based electrodes [36].