Supercapacitor performance evaluation of nanostructured Ag‐decorated Co‐Co3O4 composite thin film electrode material

Summary Nanostructured Ag‐decorated Co‐Co3O4 composite thin film (Ag/Co‐Co3O4) synthesized on nickel foam (NF) by a combination of cyclic voltammetry and pulse reverse potential electrodeposition modes presents higher specific capacitance and its retention. The higher specific capacitance of 2800 F/g on Ag/Co‐Co3O4/NF composite thin film in comparison with 2580 F/g on Co‐Co3O4/NF at 1 A/g is attributable to the presence of nanostructured Ag in the composite film enhancing the ionic and electronic conductivity of the material. The morphology revealed by the scanning electron microscope correlates the electrochemical and capacitance behavior while the energy‐dispersive X‐ray spectroscopy spectra confirmed the presence of Co, Ag, and O in the Ag/Co‐Co3O4/NF composite thin film. The attenuated total reflection‐Fourier transform infrared spectra obtained further confirmed the presence of Co–O bonds. The Ag/Co‐Co3O4/NF composite thin film presented an amorphous nature as revealed by the X‐ray diffraction spectra. In addition, the Ag/Co‐Co3O4/NF electrode exhibited a maximum specific energy of 69.5 Wh/kg, specific power of 6.6 kW/kg and capacitance retention of 82.6% after 1000 cycles, while the Co‐Co3O4 electrode (with no Ag) showed lower specific energy of 60.8 Wh/kg, specific power of 5.8 kW/kg, and a capacitance retention of 78.2% after 1000 cycles. Furthermore, by the incorporation of Ag, the composite electrode showed a reduction in the equivalence series resistance value from 1.5 Ω cm2 (Co‐Co3O4/NF) to 1.0 Ω cm2 (Ag/Co‐Co3O4/NF) as well as in the charge transfer resistance (Rct) from 2.86 Ω cm2 (Co‐Co3O4/NF) to 0.96 Ω cm2 (Ag/Co‐Co3O4/NF) indicating the positive influence of the presence of Ag in the film. The electrochemical evaluation indicates that a synergistic effect between Ag and Co‐Co3O4 enhances supercapacitor electrode performance. Ag/Co‐Co3O4 nanocomposite thin film electrodes have been prepared by electrodeposition process that combine cyclic voltammetry (CV) and pulse reverse potential (PRP). The obtained specific capacitance is 2800 F/g with stable cycling performance and capacitance retention of 82.6% even after 3000 cycles. The electrochemical evaluation indicates that a synergistic effect between Ag and Co‐Co3O4 enhances conductivity and specific surface area resulting in improved supercapacitor electrode performance.