Intrinsic pseudocapacitive enhancement of NiCo2O4/activated carbon composites for high-performance supercapacitors

Abstract

The high electrical conductivity and capacitance of NiCo2O4 have made it a promising electrode material for supercapacitors with advantages in rapid energy storage, long cycle life, and potential for flexible applications. Nickel Cobaltite Oxide (NiCo2O4) nanoflakes were successfully synthesized by the sol–gel method. The composite Activated carbon was made from waste coconut shells. The X-Ray Diffraction (XRD) pattern matches with the standard values, the crystallite sizes were found to be 7 nm using the Debye Scherrer formula. FTIR reveals the molecular bond of (NiCo2O4) NFs and their composites peak at 541 cm−1 and 552 cm−1 confirms the formation of NiCo2O4 Metal oxides. From optical absorption studies, it is found that both NiCo2O4 NFS and NiCo2O4/AC composites have maximum absorption throughout the UV region. The bandgap increases from 1.26 eV to 1.34 eV on adding AC composites to NiCo2O4 NFs. Scanning Electron microscopy (SEM) shows the formation of NiCo2O4 nanoflakes. The activated carbon has high surface area with micropores, confirmed by BET analysis. Cyclic Voltammetry (CV) analysis shows that NiCo2O4/AC composite has a more specific capacitance at low scan rate of 10 mV/s, which is more than NiCo2O4 NFs. Both the samples recorded high specific capacitance values of 142 F g−1 and 192 F g−1 at the current density of 1 A/g using GCD. From this NiCo2O4/AC composites may be a high-performing capacitor with intrinsic pseudocapacitive behaviour compared to NiCo2O4 NFs which has extrinsic pseudocapacitive behaviour.