The development of superior electrochemical energy-storage devices designed through a facile, cost-efficient, and green synthesis technique is the key to addressing the intermittent nature of renewable energy sources such as solar and wind energy. In our present work, we design a simple, surfactant-free, and low-temperature chemical strategy to prepare novel integrated, MnO2 composite electrodes with two-dimensional (2D) nanosheet film directly supported on three-dimensional (3D) conductive nickel foam. Benefiting from the specific 2D nanosheet architecture to provide a large interfacial contact area and highly conductive metal scaffolds to facilitate fast electron transfer, the novel nanosheet-assembled MnO2-integrated electrodes exhibit higher specific capacitance of 446 F g−1 at the current density of 1 A g−1 compared with nanostructured MnO2 and commercial MnO2 powder electrodes. More importantly, the as-synthesized devices are able to achieve an outstanding cycling performance of 95% retention after 3000 cycles. The present work, which is based on the low-temperature chemical route to deposit active materials on the conductive substrate, provides new insights into designing a binder-free supercapacitor system to improve the specific capacitance, cycling, and rate performance as next-generation, energy-storage devices.
Inclination to exploit renewable energy and their potential storage by facile, cost-effective, and above all in a green way are exactly what the current alternative energy research is looking for. The high-performance supercapacitor devices made up with the electrode materials synthesized in a simple and ecofriendly way are in utmost demand and the ultimate goal for widespread commercialization. Keeping these points in view, one pot green synthesis of active electrode material rGO-Au composite is achieved which not only performs as a very good supercapacitor in three-electrode configuration but also demonstrates extremely well as a coin cell device, ready to use. Ascorbic acid, which is commonly found in citrus fruits, plays an important role to reduce graphene oxide into rGO and simultaneously gold salt into gold nanoparticles, resulting in rGO-Au composite. The maximum recorded specific capacitance by CV measurement is 303.02 Fg−1 at a scan rate of 5 mVs−1. Hindrance in the commercialization is caused by the differences in the supercapacitor performances between three electrode configurations and finally the proposed device. Here the proposed coin cell device exhibits maximum areal and mass specific capacitance of 62.43 mFcm−2 and 56.09 Fg−1, respectively, that is very high among all reported graphene based composite devices benefitted over with commercially viable high capacity retention up to 80% even after 10,000 cycles. The proposed device demonstrates high energy density (∼ ED = 7.79 Wh/Kg) comparable to batteries and an optimum power density (∼ PD = 2512.9 W/Kg) close to supercapacitor insinuating it is an effective green supercapacitor for commercialization.
Supercapacitors have gained much attention in recent years due to their promising characteristics, such as high specific capacitance, high power density, long cycle life, and environment-friendly nature. Usage of natural sources for activated carbon synthesis is a major focus by many researchers worldwide for discovering a replacement of existing supercapacitors. This review summarizes the methods used to synthesize activated carbon (AC) from various natural fiber, their physical and electrochemical characteristics, and the improvement of supercapacitor electrode performance. Previous research studies indicate the practicability of activated carbon derived from various natural fibers with superior electrochemical properties. The effect of activating reagents and temperature on the electrochemical performance for supercapacitor applications are also highlighted in this paper. Since the nature of activated carbon from fibers and its synthesizing methods would result in different properties, the Cyclic Voltammetry (CV) study is also thoroughly discussed on the specific capacitance together with charge/discharge test to observe the capacitance retention after several cycles. Finally, a detailed approach of converting biowaste materials to activated carbon for energy storage applications with environmental concerns is explored.
Three-dimensional vertically aligned graphene (3DVAG) was prepared by a unidirectional freezing method, and its electrochemical performances were evaluated as electrode materials for zinc−ion hybrid supercapacitors (ZHSCs). The prepared 3DVAG has a vertically ordered channel structure with a diameter of about 20−30 μm and a length stretching about hundreds of microns. Compared with the random structure of reduced graphene oxide (3DrGO), the vertical structure of 3DVAG in a three−electrode system showed higher specific capacitance, faster ion diffusion, and better rate performance. The specific capacitance of 3DVAG reached 66.6 F·g−1 and the rate performance reached 92.2%. The constructed 3DVAG zinc−ion hybrid supercapacitor also showed excellent electrochemical performance. It showed good capacitance retention up to 94.6% after 3000 cycles at the current density of 2 A·g−1.
The current research focused on the super capacitive behavior of organic conducting polymer, i.e., polypyrrole (PPy) and its composites with gum arabic (GA) prepared via inverse emulsion polymerization. The synthesized composites material was analyzed by different analytical techniques, such as UV-visible, FTIR, TGA, XRD, and SEM. The UV-Vis and FTIR spectroscopy clearly show the successful insertion of GA into PPy matrix. The TGA analysis shows high thermal stability for composites than pure PPy. The XRD and SEM analysis show the crystalline and amorphous structures and overall morphology of the composites is more compact and mesoporous as compared to the pure PPy. The electrochemical properties of modified solid state supercapacitors established on pure polypyrrole (PPy), polypyrrole/gum arabic (PPy/GA) based composites were investigated through cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic charge–discharge (GCD). The specific capacitance of the PPy modified gold electrode is impressive (~168 F/g). The specific capacitance of PPy/GA 1 electrode has been increased to 368 F/g with a high energy density and power density (~73 Wh/kg), and (~599 W/kg) respectively.
Herein, we propose a solvent-assisted approach for preparing Ni-MOF microflowers with high specific capacitance and excellent rate capability as an electrode material for supercapacitors. Such high electrochemical performance is attributed...
Activate electrolyte enhanced supercapacitors (AEESCs) are considered as promising tools for power capacity due to their high specific capacitance and simple creation form. However, there are many challenges, such as...