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In this work, the 3D interconnected cobalt oxide nanoflakes (CON) were grown successfully on nickel foam (NF) at ambient conditions by the electrodeposition method, further followed by calcination. The deposition of Co3O4 was carried out for different deposition times of 10 min, 15 min, and 20 min and enumerated as CON-10, CON-15, and CON-20 respec...
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Due to its excellent performance, Co3O4 are redeemed as a promising supercapacitor material. However, problems like its low ion diffusion speed limit its application. In this paper, by preparing composite materials of Co3O4 and Zn(OH)F, the ion diffusion path of Co3O4 material is extended and the electrochemical performance of the material is enhan...
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... It also illustrates the higher porosity, increased surface area and slightly thicker nanoflake structure of the MN2 thin film relative to the MN4 and MN6 thin films. 36 This vertically aligned 3D porous network of interrelated nanoflakes on the SS electrode holds many active sites and aids in the Fig. 3 (a) Optical absorption spectra, (b) band gap energy diagram of MN0, MN2, MN4, and MN6 thin films. efficient transport of ions/electrons during electrochemical reactions. ...
... The inclination of the linear curve in the Nyquist plot at 45° and more with the Z′ axis is strong evidence of the rapid surface redox reactions. 36 From Table III, it is evident that the MN2 thin film electrode possesses lower ionic diffusion resistance or higher conductivity than the MN0, MN4, and MN6 thin films. Also, it has the most vertically linear Nyquist plot in the low-frequency region among all thin films, which signifies purely capacitive behavior due to increased surface area and porosity. ...
... ,36 Thus, the decreased band gap energy indicates the effective doping of Ni ions in the Mn 3 O 4 nanostructure of MN2 thin film.37 ...
We report the effect of nickel (Ni) ion doping on the structure, morphology, and supercapacitive performance of Mn3O4 thin film electrodes, deposited by a simple electrophoretic deposition technique. The structural and compositional studies of these thin films were conducted by x-ray diffraction and Fourier transform infrared spectroscopy. The morphological and optical properties were investigated by scanning electron microscopy, transmission electron microscopy, and UV–visible spectroscopy. These studies confirmed the nanoflake-type surface morphology of nickel-doped thin films. X-ray photoelectron spectroscopy provided information about various valence states and surface composition of the thin films. Cyclic voltammetry study confirmed the surface redox pseudocapacitive behavior of all thin films. The 2 mol.% nickel ion-doped thin film electrode displayed the highest specific capacitance of 816 F g−1 and was evaluated from the galvanostatic charge/discharge curve. It also exhibited outstanding cyclic stability, with 93% capacitance retention after 2000 cycles. Electrochemical impedance spectroscopy revealed the improved supercapacitive performance of the nickel-doped Mn3O4 thin film electrodes, attributed to improved conductivity and charge transport for surface redox reactions. Thus, the present study suggests that the nickel-doped Mn3O4 thin film is a promising candidate as electrode material in supercapacitors.
... Additionally, the appropriate selection and design of electrode materials and pairing up with suitable gel electrolyte composition can show remarkable improvement in the electrochemical performance of SCs [15]. To date, various binary transition metal oxides (TMOs) such as MnO 2 [16], RuO 2 [17], Co 3 O 4 [18], CuO [19], NiO [20] , MoO 3 [21], and their heterostructure [19] (or core-shell arrays) [21], ternary oxides such as NiCo 2 O 4 , MnCo 2 O 4 , ZnCo 2 O 4 , and CuCo 2 O 4 , have been investigated as electrode materials for SCs owing to their rich faradic redox reaction [22]. Among these oxides, low-cost, naturally abundant CuCo 2 O 4 spinel cobaltite has been reported as a promising electrode material for SCs due to its high conductivity and multiple oxidation states of Co [23]. ...
The redox additive in an aqueous gel electrolyte is reported as one of the efficient methods to improve the electrochemical supercapacitor performance. Here, we report the role of redox additive, potassium ferricyanide((K3[Fe(CN)6]), referred to as KFCN) for improving the electrochemical performance of binder-free, CuCo2O4 (CCO) nanowire arrays (NWs) based solid state symmetric supercapacitors (SSCs). The crystal structure and morphology of prepared CCO films are confirmed by X-ray diffraction (XRD) and field emission-transmission electron microscopy (FE-TEM). The elemental composition of CCO films is estimated as Cu0.5Co2.77O3.82 via energy-dispersive X-ray spectroscopy (EDS) analysis. Surprisingly, the areal capacitance (or energy density at 5 mAcm−2) is significantly improved from 0.58 F cm−2 (or 0.016 mWh cm−2) to 10.5 F cm−2 (or 0.296 mWh cm−2), respectively, after the addition of KFCN to aqueous KOH electrolyte, as compared to bare KOH. Furthermore, CCO exhibits decent cyclic stability with 90 % capacitance retention up to 5000 CV cycles at the scan rate of 100 mV s−1. Moreover, 2-terminal CCO NWs-based SSCs, employed with PVA-KOH-KFCN gel electrolyte, demonstrate a wider potential window of −0.9 to 0.9 V (1.8 V) with a 7-fold increase of energy density from 9.1 to 65 Wh kg−1, as compared with that of PVA-KOH gel electrolyte. As practical validation, the operation of Red-LED for 3 min is demonstrated with PVA-KOH-KFCN gel-based SSC, manifesting that adding redox substance in aqueous electrolytes is one of the promising strategies for portable and wearable energy storage systems
