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Supercapacitors are highly attractive for a large number of emerging mobile devices for energy storage and harvesting issues. This mini-review presents a summary of the recent developments in supercapacitor research and technology, including all kinds of supercapacitor design techniques using various electrode materials and production methods. It a...
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... is observed, meaning during this process charge transfer occurs across the electrodeelectrolyte interface. Whereas in the non-faradaic process, which is addressed after this, is where Faraday's law is not obeyed i.e. charge transfer does not occur, e.g. adsorption-desorption at the electrolyte-electrode interface, solvent dipole reorientation In Fig. 2 the main classification of EDLC is given that is partly based on There are plenty of pros and cons while speaking of EDLC devices that cannot be discussed in detail in a short review article. Therefore, here we concentrate on the most important features. For instance, charging and discharging cycles are highly reversible due to its ...
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... It is clear that there are no redox reaction peaks recorded, which indicates that the electrode exhibited good capacitive behaviour for a symmetric supercapacitor. The figure also The relatively not-so-high calculated Csp value as compared to the literature data is most probably due to the high electrode loading or high active mass on the current collector [31]. Possibly, minimizing the electrode active mass might be a potential solution for achieving a high specific capacitance value. ...
Two-dimensional (2D) materials, inclusive of molybdenum disulfide (MoS2), are auspicious due to their structure providing absorption sites and shorter diffusion paths. However, their sheet restacking affects the functional properties, resulting in the device’s low efficiency. A strategy is proposed to combine MoS2 with MXene material. X-ray Diffraction data revealed peaks at d-spacings of 6.07, 2.72, 2.49, 2.27, 1.82, and 1.53 Å. X-ray photoelectron spectroscopy shows prominent peaks for C 1s and Ti 2p, with no signal for Al detected in the pristine Ti3C2 MXene. This indicates successful etching of the Al layer. Electron Microscopes were used to confirm the samples’ morphology and showed that the hybrid sample has a layered flake-like structure with a small sphere attached to the surface. While the HR-TEM confirmed the layered structure of Ti3C2 after exfoliation from Ti3AlC2, consistent with prior studies. Prior, the electrochemical performances of the MXene/MoS2 supercapacitor in 6M KOH aqueous electrolyte were examined through cyclic voltammetry and galvanostatic charge–discharge. The highest specific capacitance reached was 139.71 Fg-1, attributed to heterostructures of an equally distributed MoS2 and MXene. Furthermore, the device retained about 83% of its initial capacitance after 10,000 cycles of cyclic stability testing. The results demonstrated that the MXene material improved the capacitive performance of MoS2, and conversely. Further enhancements can be expected as a result of a major omission in electrode synthesis, particularly the importance of delamination in MXene preparation.
... The h-g-C 3 N 4 or GCN and PC electrochemical measurements were carried out using an electrochemical workstation PGSTAT 204 Autolab, Netherlands, with FRA 32 M Module operated NOVA software. The counter or auxiliary electrode was platinum, the reference electrode was Ag/AgCl (saturated in 3 M KCl solution) [51], and the working electrode was manufactured in DMF with sonication until the homogenous slurry was obtained [52]. A soft and very thin sheet of graphite was used for the experiments. ...
... A supercapacitor contains two electrodes, generally made of carbon-based materials, with a small separation. The basic electrostatic charge storage mechanism is that when voltage is applied to the electrode of an SC, the electrolytic ions in the solution are transferred to the opposite electrodes and create a dual layer of charge on the surface of both electrodes (Najib and Erdem, 2019;Dhapola et al., 2022). The key aspects that contribute to the high energy storage capacity of SCs are the large surface area (which can be gained by using porous materials) and low electrolyte separation (which causes easy movement of ions). ...
A significant amount of energy can be produced using renewable energy sources; however, storing massive amounts of energy poses a substantial obstacle to energy production. Economic crisis has led to rapid developments in electrochemical (EC) energy storage devices (EESDs), especially rechargeable batteries, fuel cells, and supercapacitors (SCs), which are effective for energy storage systems. Researchers have lately suggested that among the various EESDs, the SC is an effective alternate for energy storage due to the presence of the following characteristics: SCs offer high-power density (PD), improvable energy density (ED), fast charging/discharging, and good cyclic stability. This review highlighted and analyzed the concepts of supercapacitors and types of supercapacitors on the basis of electrode materials, highlighted the several feasible synthesis processes for preparation of metal oxide (MO) nanoparticles, and discussed the morphological effects of MOs on the electrochemical performance of the devices. In this review, we primarily focus on pseudo-capacitors for SCs, which mainly contain MOs and their composite materials, and also highlight their future possibilities as a useful application of MO-based materials in supercapacitors. The novelty of MO’s electrode materials is primarily due to the presence of synergistic effects in the hybrid materials, rich redox activity, excellent conductivity, and chemical stability, making them excellent for SC applications.
... As demand for electronic devices such as electric cars, smartphones, and energy storage plants continues to grow, researchers are working on developing electrochemical storage equipment with higher power as well as energy density [1][2][3]. When the energy storage device is charged and discharged fast, it generates a lot of heat, and the constant heat accumulation makes the internal pressure of the device increase and becomes unstable [4][5][6][7][8], which can even burn out the energy storage device or explode under extreme conditions [9,10]. Therefore, developing a reliable, eco-friendly, and cost-effective method to stop thermal runaway is very important. ...
The lifetime and application of electrochemical storage devices are always threatened by thermal runaway. Intelligent self-protecting gel electrolytes can be designed using temperature-responsive polymers. However, the mechanisms and factors affecting protective behavior are unclear. Here, we fabricated supercapacitors using temperature-responsive polyacrylamide-2-hydroxyethyl acrylate (PNIPAM-co-HEA) hydrogel polyelectrolytes. It was found that the polymer changed from hydrophilic to hydrophobic with increasing temperature, and the physical cross-linking of the polymer molecular strands in the electrolyte was enhanced, thus restricting conductive ion migration and closing the ion transportation pathway. The hydrophilic–hydrophobic transition on the gel surface also contributed to the suppression of the specific capacitance of the supercapacitor. This self-protection feature is repeatable. In addition, we investigated the effect of methyl groups in the main chain structure on the electrochemical properties using poly(N-isopropylacrylamide-co-2-hydroxyethyl methacrylate) (PNIPAM-co-HEMA). Methylene enhanced the hydrophobicity of the polymer at room temperature and reduced the thermo-protective effect. The methyl group in the main chain also reduced the thermal response temperature of the polymer. This study explores the mechanism by which temperature-responsive polymers inhibit thermal runaway in supercapacitors and provides support for the design of more rational and efficient temperature-sensitive electrolytes.
... Supercapacitors are rapidly advancing in the field of energy storage technology owing to their fast charge-discharge characteristics, high power density, and long lifespan. The electrode materials of supercapacitors are important factors that directly affect the energy and power densities of energy-storage devices [1,2]. Two-dimensional (2D) materials are suitable as electrode materials in supercapacitors because of their thinness, large specific surface area, and mechanical stability, and they can be easily modified and functionalized to enhance their properties [3,4]. ...
In this paper, we report a titanium dioxide/polypyrrole/phosphorene (TiO2/PPy/phosphorene) nanocomposite as an active material for supercapacitor electrodes. Black phosphorus (BP) was fabricated by ball milling to induce a phase transition from red phosphorus, and urea-functionalized phosphorene (urea-FP) was obtained by urea-assisted ball milling of BP, followed by sonication. TiO2/PPy/phosphorene nanocomposites can be prepared via chemical oxidative polymerization, which has the advantage of mass production for a one-pot synthesis. The specific capacitance of the ternary nanocomposite was 502.6 F g−1, which was higher than those of the phosphorene/PPy (286.25 F g−1) and TiO2/PPy (150 F g−1) nanocomposites. The PPy fully wrapped around the urea-FP substrate provides an electron transport pathway, resulting in the enhanced electrical conductivity of phosphorene. Furthermore, the assistance of anatase TiO2 nanoparticles enhanced the structural stability and also improved the specific capacitance of the phosphorene. To the best of our knowledge, this is the first report on the potential of phosphorene hybridized with conducting polymers and metal oxides for practical supercapacitor applications.
... Carbon-based materials are commonly employed as electrodes in EDLCs, while transition metal oxides and conducting polymers are frequently utilized as electrode materials for pseudocapacitors. The capacitors with carbon-based electrode materials suffer from low energy storage and poor stability, which conducting polymer layer tends to detach from the substrate [7][8][9]. Therefore, transition metal oxides (TMOs) are favored by researchers because of their generally large theoretical specific capacitance and are often used as electrode materials in energy storage supercapacitors [10]. ...
... The symmetrical shapes of the CV and GCD curves of the devices tested at different scanning speeds and current densities indicate that the two electrode materials are well matched and have excellent charge/discharge reversibility [38]. The power and energy density of the P-MnMoO 4 //AC ASC device can be computed using Equations (7) and (8). The energy density of P-MnMoO 4 //AC was 41.9, 34.8, 27.6, 25.3, and 21.2 Wh kg −1 for power densities of 666. ...
Manganese molybdate has garnered considerable interest in supercapacitor research owing to its outstanding electrochemical properties and nanostructural stability but still suffers from the common problems of transition metal oxides not being able to reach the theoretical specific capacitance and lower electrical conductivity. Doping phosphorus elements is an effective approach to further enhance the electrochemical characteristics of transition metal oxides. In this study, MnMoO4·H2O nanosheets were synthesized on nickel foam via a hydrothermal route, and the MnMoO4·H2O nanosheet structure was successfully doped with a phosphorus element using a gas–solid reaction method. Phosphorus element doping forms phosphorus–metal bonds and oxygen vacancies, thereby increasing the charge storage and conductivity of the electrode material. The specific capacitance value is as high as 2.112 F cm−2 (1760 F g−1) at 1 mA cm−2, which is 3.2 times higher than that of the MnMoO4·H2O electrode (0.657 F cm−2). The P–MnMoO4//AC ASC device provides a high energy density of 41.9 Wh kg−1 at 666.8 W kg−1, with an 84.5% capacity retention after 10,000 charge/discharge cycles. The outstanding performance suggests that P–MnMoO4 holds promise as an electrode material for supercapacitors.
... [1][2][3] SCs are distinct either from the traditional capacitors or batteries, capable of delivering higher power density, speedy charging, and relatively longer life-span riveting them as suitable candidates for a variety of energy storage applications. [4][5][6][7][8][9][10] The selection of electrode material for SC depends on the type of application in hand and oen involves a trade-off between factors such as specic capacitance, energy density, and the cost of material synthesis and processing. Metal sulphides have emerged as a prominent class of SC material compared to the metal oxides due to their, (i) higher electronic conductivity (arising from the lower electronegativity of S-atom) allowing faster electron transfer during the charging-discharging cycles, (ii) larger pseudocapacitance (due to the reversible faradaic redox-reaction) behaviour that provides additional capacitive storage of energy, (iii) better cycling stability which leads to the long-term reliability, and (iv) higher energy density offering faster storage and release of energy for suitable application. ...
The study presents a novel, one-pot, and scalable solid-state reaction scheme to prepare bismuth sulphide (Bi2S3)-reduced graphene oxide (rGO) nanocomposites using bismuth oxide (Bi2O3), thiourea (TU), and graphene oxide (GO) as starting materials for energy storage applications. The impact of GO loading concentration on the electrochemical performance of the nanocomposites was investigated. The reaction follows a diffusion substitution pathway, gradually transforming Bi2O3 powder into Bi2S3 nanostrips, concurrently converting GO into rGO. Enhanced specific capacitances were observed across all nanocomposite samples, with the Bi2S3@0.2rGO exhibiting the highest specific capacitance of 705 F g⁻¹ at a current density of 1 A g⁻¹ and maintaining a capacitance retention of 82% after 1000 cycles. The superior specific capacitance is attributed to the excellent homogeneity and synergistic relation between rGO and Bi2S3 nanostrips. This methodology holds promise for extending the synthesis of other chalcogenides-rGO nanocomposites.
... Discussions on the use of ZnO and different compounds based on it, such as ZnO-CoO, as well as ZnO-CoO core-shell nanostructures for energy storage/ conversion, lithium-ion batteries, and supercapacitors, can be found in recent reviews [41][42][43][44][45]. Yan et al., prepared a three-dimensional nanostructure of CoO/ZnO-NrGO using a simple solvothermal method followed by freeze-drying, in which CoO/ZnO nanoclusters were fixed on N-doped 3D reduced graphene oxide as the anode material for a lithium-ion battery [46]. ...
... The synthesis of zinc compounds with other transition metals, such as Mn, Mo, Ni, etc., as well as with carbon materials, makes it possible to achieve high specific capacitance values, and several ZnO-based systems have been tested as an electrode material for supercapacitors [14,41,43]. Solid solutions of quaternary transition metal oxides such as NiCoMoZnO x have also been tested as a material for supercapacitors and have shown promising results with a capacity of 0.41 mA h cm −2 , corresponding to the CF value of 2.12 F cm −2 obtained for NiCoMoZnO x electrodes [58]. ...
... Composites containing zinc and cobalt oxides in various forms have also shown a good performance when used as electrode materials for supercapacitors [14,[41][42][43][44][45][46][47]. Using a ZnO/CoO composite as the electroactive material in an electrode exhibits an enhanced super-capacitive performance of 85 mA h g −1 (~681 F g −1 ), attained at a significantly high current density of 20 A g −1 [49]. ...
Zinc oxide (ZnO) and materials based on it are often used to create battery-type supercapacitor electrodes and are considered as promising materials for hybrid asymmetric supercapacitors. However, when creating such electrodes, it is necessary to take into account the instability and degradation of zinc oxide in aggressive environments with a non-neutral pH. To the best of our knowledge, studies of the changes in the properties of ZnO-containing electrodes in alkaline electrolytes have not been carried out. In this work, changes in the structure and properties of these electrodes under alkaline treatment were investigated using the example of ZnO-containing composites, which are often used for the manufacturing of supercapacitor electrodes. Supercapacitor electrodes made of two materials containing ZnO were studied: (i) a heterogeneous ZnO-Co3O4 system, and (ii) a hexagonal h-Zn-Co-O solid solution. A comparison was made between the structure and properties of these materials before and after in situ electrochemical oxidation in the process of measuring cyclic voltammetry and galvanostatic charge/discharge. It has been shown that the structure of both nanoparticles of the heterogeneous ZnO-Co3O4 system and the h-Zn-Co-O solid solution changes due to the dissolution of ZnO in the alkaline electrolyte 3.5 M KOH, with the short-term alkaline treatment producing cobalt and zinc hydroxides, and long-term exposure leading to electrochemical cyclic oxidation–reduction, forming cobalt oxide Co3O4. Since the resulting cobalt oxide nanoparticles are immobilized in the electrode structure, a considerable specific capacity of 446 F g−1 or 74.4 mA h g−1 is achieved at a mass loading of 0.0105 g. The fabricated hybrid capacitor showed a good electrochemical performance, with a series resistance of 0.2 Ohm and a capacitance retention of 87% after 10,000 cycles.
... In this scenario, energy storage emerges as a crucial component in pursuing clean energy, addressing how alternative energy sources will be inserted into the current energy grid [1]. Supercapacitors stand out as a superior choice within the spectrum of energy storage solutions, including batteries and conventional capacitors, once they can store and release substantial energy quantities rapidly and undergo charging and discharging cycles several times [2][3][4][5]. ...
This study presents a cost-effective approach to developing MnO2-based, aiming to understand how modifications with Ce can affect the materials' morphology, properties, and application; thus, we comprehensively studied such properties. Interestingly, when just precursors for MnO2 were used, nanowires were obtained using a hydrothermal method. However, the subsequent doping with varying concentrations of Ce induced notable changes in the material morphology. Although the morphology changed, the surface areas and porous volumes increased with Ce content. X-ray diffraction analysis revealed the presence of the α-MnO2 tetragonal crystal phase in all materials, suggesting uniform Ce distribution and the absence of distinct crystalline phases. Such properties are vital for storage issues; thus, we decided to evaluate the physicochemical properties of the materials in supercapacitor evaluations. When submitted to electrochemical assessments, the materials presented pseudocapacitive behavior; also, tests for pseudosupercapacitors showed an increase in the specific capacitance with Ce-doping. Notably, these materials exhibited remarkable stability, increasing specific capacitance after 1000 charge–discharge cycles at high current rates. After choosing the optimum conditions of Ce-doping quantity, which did not show a tailored morphological control, an asymmetric supercapacitor was prepared; the device demonstrated a broad potential window, excellent rate performance, and the ability to maintain specific capacitance across various current densities. Remarkably, the asymmetric supercapacitor exhibited an energy density of 785.2 Wh kg⁻¹ at a power density of 2880.02 W kg⁻¹, marking a significant advancement in energy storage capabilities. Here, we have shown that the morphological control was not mandatory for the application of the materials. Furthermore, incorporating Ce into MnO2 enhanced supercapacitor performance, suggesting chemical composition is as vital as morphology in high-performance energy storage.
... Activated carbon and CNTs are notable examples of EDLCs, thanks to their exceptional conductivity, large surface area and unique nanoscale effects [10,11]. In recent years, graphene has proven to be the most promising material for energy storage applications owing to its excellent electrical and thermal conductivity, outstanding chemical stability, superior mechanical strength and higher specific surface area compared to other carbon materials [12,13]. However, the limited theoretical capacitance of graphene restricts its further applications due to the disruption of graphene's atomic configuration, which significantly affects its thermal, electronic and magnetic properties [14]. ...
