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Bimodal NiCo2O4·MnO2 (NCM) nanorods were grown on carbon fiber paper (CFP) using a hydrothermal process. The structural and morphological studies were performed via powder X-ray diffraction and field-emission scanning electron microscopy, respectively. The aspect ratio of the developed electrode significantly improved up to a threshold concentration of manganese in the Ni/Co binary oxide, and thereafter decreased. The capacitive performance and electrochemical parameters of the developed NCM nanorods were analyzed using cyclic voltammetry, galvanostatic charge–discharge, and impedance spectroscopy. The maximum specific capacitance of the developed NCM nanorods was found to be 2575 F g−1 (305 mA h g−1) at a current density of 5 A g−1. Additionally, the excellent cyclic retention of nearly 92.5% was achieved for the NCM nanocomposite even after 5000 cycles. Also, the response time (τo) calculated from the Bode plot was found to be ∼22 s, which validated the fast charging of the developed electrode material. Furthermore, an asymmetric solid-state supercapacitor (ASC) device was successfully assembled utilizing NCM (1 : 2 : 2) nanorods and activated carbon as positive and negative electrodes, respectively. The developed device achieved a capacitance of 130 F g−1 (176.1 mA h g−1) with an energy density and power density of 138 W h kg−1 and 722 W kg−1, respectively, which could illuminate an LED bulb (1.8 V) for 50 min.

Due to environmental crisis and developed numerous portable electronic device and electric vehicles, it is necessary to find commercial alternative energy source to fulfil the future charge storage demand. In the present work, we have addressed the facile sol–gel root for the synthesis of Bismuth ferrite (BFO) along with modified carbon solution. The effect of carbon on structure, morphology and electrical properties on the BFO ceramic were investigated. XRD study reveals the prepared samples were found to be highly amorphous and rhombohedral structure. The morphology analysis demonstrates that the modified BFO nanoparticles size (∼20 nm) is smaller than pure BFO of size (∼30 nm) which helps to reduces the leakage current and improved electrical properties. Influence of carbon solutions on the BFO have been investigated for supercapacitor application. The modified BFO exhibited good electrochemical energy storage performance with a specific capacity of 678 Fg−1 at a scan rate of 5 mVsec−1 and excellent cyclic retention ∼90.5% even after 3000 cycles. In addition, the developed electrode materials are used to fabricate an asymmetric solid-state supercapacitor (ASC) device for demonstrating the practical applicability.

Binary metal sulfides have synthesized at ambient temperature as a positive electrode using ethanol-water as a solvent in the co-precipitation process. The incorporation of sulfur (S) into transition metals could have controlled by changing the solvents, including ethanol and water. The average particle size was measured around 15 nm using electron microscope. The specific surface area calculated around 145 m2 g-1 through NMR based relaxation method. Moreover, it has been found that the particular composition of CNS 1:1:0.15 has drawn immense electrochemical properties based on their discrete morphology. The binary sulfide electrode exhibits excellent pseudocapacitance performance, and delivered specific capacitance (SC) of 2910 F g-1 at 1 A g-1, and simultaneously depicted adequate cyclic retention ~91.5 % up to 10,000 cycles. The energy density (ED), and power density (PD) were evaluated for active electrode about ~123 Whkg−1 and ~285 W kg-1 respectively. Meanwhile, the influence of cation species (Na+, K+& Li+) in electrolyte concentrations illustrates the outstanding supercapacitive performance by decreasing internal resistance. An asymmetric solid-state (ASC) supercapacitor device was assembled which brighten the ~1.8 V of commercial LED for the validation of electrode.

The successive ionic layer adsorption and reaction (SILAR) experimental process has been used to develop a high-efficiency electrode of MFe2O4 (M = Ni, Co and Mn) on substrates at ambient temperature. Structural, morphological and electrochemical properties have been investigated using x-ray diffraction (XRD), a scanning electron microscope (SEM) and an electrochemical test station, respectively. A morphology resembling the Hydrangea macrophylla flower has been observed and tuned with varying Fe concentration. The formation of MFe2O4 demonstrates the efficient electrochemical behavior and the specific capacitance has been evaluated as ∼1380, ∼972 and ∼815 Fg-1 for CoFe2O4 (CF), NiFe2O4 (NF) and MnFe2O4 (MF), respectively, at a current density of 1 Ag-1. Also, the developed electrodes maintain excellent cyclic retention of ∼92%, ∼89% and ∼86% for CF, NF, and MF, respectively, up to 5000 cycles. Further, asymmetric solid-state supercapacitor (ASC) devices have been fabricated using the best compositions of MFe2O4 as a positive electrode and carbon black (CB) as a negative electrode, and successfully illuminate a 1.8 V commercial LED.

We demonstrate a green, facile and rapid microwave-mediated process for fabricating carbon black (CB) incorporated Ni/Co hydroxide porous nanocomposites and study the effect of various mass loading of CB on supercapacitor performance. The structure and interactions between CB and Ni/Co hydroxide are characterized by using x-ray diffraction, Fourier-transform infrared spectroscopy and x-ray photoelectron spectroscopy, which suggest the miniaturization of the single-phase Ni/Co hydroxide formation time. A morphology study reveals that the addition of CB into Ni/Co hydroxide develops a loose network structure with well-defined architectural pores. In addition, the nanocomposites demonstrate noticeable improvements in porosity and atomic ratio of Ni/Co with an increasing percentage of carbon, which results in a higher diffusion of electrolytes, and hence electrical conduction. The developed electrode materials exhibit a maximum specific capacitance value of 1526 Fg-1 at current density 1 Ag-1 with excellent cyclic stability (92% retention at 5000 cycles), energy density (76 Wh Kg-1), power density (250 W Kg-1) and rate capability. A solid state asymmetric supercapacitor device is fabricated and utilized to brighten a commercial LED effectively for validating real usage.