posted on 2024-01-05, 10:29authored byKaumudi Yadav, Manoj Mayaji Ovhal, Saurabh Parmar, Nishant Gaikwad, Suwarna Datar, Jae-Wook Kang, T. Umasankar Patro
A binder-free, electrically conducting
nickel cobalt oxide (NiCo2O4)-reticulated vitreous
carbon (RVC) foam (NiCo2O4@RVC) electrode was
prepared by template carbonization
of open-cell polyurethane foam followed by the hydrothermal growth
of NiCo2O4 nanoneedles, leading to the formation
of a hierarchical porous electrode. The growth of NiCo2O4 nanoneedles (length and diameter) on RVC foam was found
to depend on hydrothermal coating time, which varied between 6 and
12 h. However, optimally grown NiCo2O4 nanoneedles
for 8 h on an RVC foam with an average diameter of 77(±9) nm
and length of ∼2 μm exhibited the lowest charge-transfer
resistance, resulting in the areal capacitance (Ca) of ∼2.45 F/cm2 at a scan rate of
5 mV/s. A symmetric supercapacitor (SC) device exhibited a maximum Ca of 1.22 F/cm2 at a current density
of 1 mA/cm2 and an energy density of 2.51 W h/kg at a power
density of 30 W/kg. The SCs showed a capacitance retention of ∼97%
after 10,000 galvanostatic charge/discharge (GCD) cycles, apparently
due to a highly stable NiCo2O4 structure on
the RVC network structure, which was ascertained by various characterization
techniques after the GCD cycles. Further, the SC module, comprising
three devices in series, successfully lights up an LED, demonstrating
the energy storage capability of these electrodes in real applications.
Owing to its excellent electrochemical performance, the NiCo2O4@RVC electrode offers a low-cost and efficient alternative
material in energy storage applications.