Enhanced electrochemical performance of mesoporous NiCo₂O₄ as an excellent supercapacitive alternative energy storage material

Highlights: • A facile technique to grow mesopores NiCo₂O₄ flakes. • High specific capacitance. • High capacitance retention at higher cycles. • A promising candidate for energy storage device. - Abstract: Here we report the supercapacitive properties of mesoporous nickel cobalt oxide (NiCo₂O₄) synthesized by fast, inexpensive and facile chemical bath method, by avoiding high pressure, high temperature and chemical complexity. Physico-chemical characterization techniques such as X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), Raman Spectra, and nitrogen adsorption–desorption isotherm analysis is performed to characterize the electrode material. Brunauer-Emmett-Teller (BET) measurements reveal the surface area 52.86 m² g⁻¹ and from Barrett-Joyner-Halenda (BJH), typical pores size ranges between 10 and 50 nm, also confirms the mesoporosity. The electrochemical properties are measured by cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charging/discharging. The synthesized material exhibits remarkably enhanced electrochemical performance with specific capacitance of 1130 F g⁻¹ at 1 mV s⁻¹ sweep rate and 1125 F g⁻¹ at current density of 0.05 A g⁻¹, highest without supporting base like carbon cloth, Ni-foam, Ti- foil used for direct growth (deposition) of electrode material. It is superior to those of its individual and hybrid components prepared by similar technique. Ragone plot shows high specific energy density (49.25 Wh kg⁻¹) and corresponding specific power density (1851.31 W kg⁻¹) even at high current density of 0.5 A g⁻¹.