Redox Additive Electrolyte Research Articles

Highly porous ZIF-67/KLAC composite for enhanced supercapacitor performance with redox additive electrolyte

To enhance the efficiency of supercapacitors, the selection of appropriate electrode materials as well as electrolytes is essential. Highly porous materials have gained attention as electrode material while Redox Additive Electrolytes (RAE) have gained popularity as effective alternatives to traditional aqueous electrolytes. The present study discusses the fabrication of a highly porous Co-MOF (ZIF-67) grown on Keekar leaves-derived activated carbon (KLAC) to develop a suitable composite using a simple and inexpensive approach. The grown ZIF-67 material shows a polyhedron kind of morphology over the surface of KLAC with an overall surface area of 1012 m2/g. The synthesized material was evaluated for a three-electrode configuration in a 1 M Na2SO4 aqueous electrolyte and 0.2 M K3[Fe(CN)6] in 1 M Na2SO4 (RAE). The ZIF-67/KLAC composite exhibits a high capacitance of 2880 F/g when electrochemically tested within RAE, at a specific current of 5 A/g as compared to 33.11 F/g when tested in 1 M Na2SO4 aqueous electrolyte, over a potential range of −0.1–0.5 V. Also, the cyclic stability in RAE is found to be superior (∼100 %) as compared to 1 M Na2SO4 (∼95.30 %) after continuous 5000 charge-discharge cycles. The lower resistance in RAE allows for faster ionic and electronic transmission, resulting in superior cyclic stability. Due to the excellent electrochemical outcomes, the suggested synergic of ZIF-67/KLAC/RAE may work as a highly effective supercapacitor assembly in the future.

Influence of electrolyte additives on a pebble-shaped Mn2V2O7 electrode for electrochemical performance

In this study, pebble-shaped Mn2V2O7 nanoparticles have been synthesised by a simple hydrothermal technique. PXRD, FTIR, and FESEM-EDS studies have been used to investigate the structural and morphological nature of the material. The electrochemical performance has been conducted using two and three electrode configurations in redox additive electrolytes (RAE). It exhibits the highest specific capacitance of 3788.21 F/g at 6 A/g current density. After 10,000 cycles, the fabricated device shows a capacity retention of about 77.56 %.

Fabrication and performance assessment of coin cell supercapacitors with multiwalled carbon nanotube-supported mixed metal oxide nanocomposites and redox additive electrolyte

In the realm of supercapacitor applications, the fabrication of coin cell supercapacitors with superior performances played a crucial role. In this work, an asymmetrical type coin supercapacitor was fabricated with multiwalled carbon nanotube supported mixed metal oxide (CuO/CoO@MWCNT - CCM) nanocomposites (NCs) and potassium ferrocyanide incorporated KOH based redox additive electrolyte (RAE). The synergistic effect and the enhanced conductivity by the mixed metal oxides and MWCNT, respectively, were acted as the performance enhancer for electrode performances. On the other hand, RAE with optimized concentration provided additional redox active sites for superior performances. The combined effect of CCM NCs and RAE, were responsible for the superior performances. CCM NCs were prepared by one-pot hydrothermal technique and characterized. Working electrodes with CCM NCs were fabricated by doctor blade method and evaluated in KOH and RAE. It exhibited 1838.55 Fg−1 of specific capacitance (Csp) in RAE. Assembled asymmetrical supercapacitors with CCM NCs modified working electrode and activated carbon based anode, delivered 123.91 Fg−1 of Csp at 2.75 Ag−1 in RAE. The assembled supercapacitors delivered the highest energy density of 27.53 Wh kg−1 and power density of 1875 W kg−1 in RAE with an impressive 82.89 % of cyclic retention after 5000 GCD cycles. Finally, an asymmetric coin cell supercapacitor (CR2302) was fabricated with CCM NCs and RAE. The fabricated coin cell delivered the charge and discharge capacities of 157.72 and 55.99 mAh g−1, respectively in KOH, whereas these values were significantly improved 172.46 and 126.2 mAh g−1 respectively, in RAE. It proved that the fabricated coin cell supercapacitors performed well in terms of maximum charge and discharge performances in RAE compared to conventional KOH.

Facile synthesis of MCo2O4(M= Ni, Cu, and Zn) materials for high-performing electrochemical capacitors with robust cyclic stability using redox additive electrolyte

Developing efficient electrochemical capacitors relies heavily on the quality of electrode materials and electrolytes used. This report presents the successful solvothermal synthesis of three cobaltites, NiCo2O4, CuCo2O4, and ZnCo2O4, and their electrochemical performance in a 2M KOH solution. Among the three cobaltites, NiCo2O4 showed the best electrochemical performance with a specific capacity of 178 C/g with FTO (fluorine-doped tin oxide) as the current collector. In addition, the performance of NiCo2O4 was tested in different aqueous electrolytes, including KOH, NaOH, NaCl, and Na2SO4, and the specific capacity was found to vary in the order of 2 M KOH > 2 M NaOH > 2 M NaCl > 2 M Na2SO4. The performance of NiCo2O4 was also assessed in various concentrations of KOH electrolyte (2 M KOH, 3 M KOH, and 4 M KOH), and the best performance was observed in 3 M KOH with a specific capacity of 928.3 C/g with Ni foam as the current collector. Finally, using redox additive electrolytes, the performance of synthesized NiCo2O4 was evaluated in both 3-electrode and 2-electrode systems. No studies have been conducted on the electrochemical performance of NiCo2O4 with KFCN redox additive in a 3 M KOH electrolyte. In the three-electrode system, NiCo2O4 showed a high specific capacity of 1005.5 C/g at 1 A/g, with 167 % capacity retention after 1000 charge-discharge cycles at a high current density of 30 A/g. The NiCo2O4//Activated Carbon asymmetric hybrid supercapacitors in two-electrode systems exhibited a maximum specific capacity of 115.6 C/g and a specific energy density of 85 Wh/kg at a specific current density of 1 A/g. They also showed a capacitive retention of 120% after 5000 charge-discharge cycles. The maximum power density was 13225 W/kg at a current density of 5 A/g while maintaining an energy density of 22 Wh/kg.

Boosting supercapacitor performance synergistically with Bi2O3/MnO2:rGO nanocomposites and redox additive electrolyte

The contemporary surge in energy demand underscores the imperative for improvements in energy conversion and storage technologies. In response, supercapacitor devices were engineered using nanocomposites (NCs) of Bi2O3/MnO2:rGO (BMR), and their electrochemical performance was systematically documented. The BMR NCs were hydrothermally prepared and their physicochemical characteristics were analyzed. The working electrode was constructed employing BMR NCs, and tested in a three-electrode setup to explore its electrochemical properties using the aqueous electrolytes consisted of 1 M KOH and 0.1 M K4[Fe(CN)6] added 1 M KOH (referred as Redox additive electrolyte - RAE). BMR NCs loaded working electrode exhibited 1441.1 Fg−1 of specific capacitance at 5 mVs−1 in RAE. Subsequently, asymmetrical supercapacitor devices were assembled, incorporating a cathode comprised of BMR NCs modified Ni foam and rGO-loaded Ni foam as an anode. The supercapacitor performances were evaluated using KOH and RAE in a two-electrode setup. The BMR NCs loaded supercapacitors demonstrated 9.42 Whkg−1 and 2100 Wkg−1, of energy and power densities, respectively, in KOH. Obtained energy and power density values were improved to 16.08 Whkg−1 and 2800 Wkg−1, respectively, by the utilization of RAE. Since the synthesized BMR NCs exhibited superior performances in RAE, the suggested combination of BMR NCs and RAE emerged as a more promising option for energy storage applications in real-time.

Zn-based coordination polymer derived N-doped defective carbon for high energy density supercapacitor using aqueous, dual redox additive and ionic liquid electrolytes

Porous carbons are excellent supercapacitor materials due to their high-power density, rapid charge-discharge rates and extended cycling stability. However, the restricted energy density poses a bottleneck for their practical applications. The ideal approach to enhance the energy density is by utilizing redox additives and ionic liquid electrolytes. Herein, the defect-rich nitrogen-doped porous carbons (N-PCs) are synthesized at 700, 850 and 1000 °C using Zn-BTC BPY coordination polymers as the sacrificial template for high energy density supercapacitor application. The defect density increases while the percentage of N-doping decreases with the increase in carbonization temperature. In three-electrode system, N-PC-1000 carbon delivered a high capacitance of 151 F g-1 at 1 A g-1, whereas N-PC-700 and N-PC-850 carbons delivered capacitance of 129 and 87 F g-1, respectively, with more than 98% capacitance retention. Additionally, the N-PC-1000||N-PC-1000 symmetric coin cell device delivered high energy densities of 14.2 and 16.9 Wh kg-1 in organic (KOH + HQ) and inorganic-organic dual redox additive (KOH + KI + HQ) electrolytes, respectively. Further, the assembled symmetric device demonstrated maximum energy and power densities of 31.3 Wh kg-1 and 15,881 W kg-1, respectively in [EMIM][ESO4] ionic liquid electrolytes, while retaining 99 % capacitance over 6000 GCD cycles. Overall, this study presents the idea of using coordination polymer-based porous carbons for developing next generation energy storage devices.

Enhancement of energy density for iron MOF-derived composite for aqueous supercapacitor by K3[Fe(CN)6] redox additive electrolyte

Redox additive added aqueous electrolyte attract extensive interest in supercapacitor application. Herein, the electrochemical of the synthesized Fe3O4/Si/GNP composite cathode electrode material was conducted in a two-electrode system via Swagelok cell assembly in the presence of with and without redox additive (0.2 M K3Fe(CN)6 in 1 M Li2SO4). The Fe3O4/Si/GNP composite was successfully synthesized by facile solvothermal method followed by calcination. The structural and morphology investigations of the Fe3O4/Si/GNP composite are conducted via XRD, FESEM, and BET analyses. The synergic effects between the composite material and redox-active ion (Fe2+/Fe3+) in the redox additive electrolyte enhance faradaic reactions, which are utilized to design a high-energy density supercapacitor. The Fe3O4/Si/GNP composite in redox additive electrolyte exhibits a 64.38 % increase in specific capacitance (319.45 F g−1 at 1 A g−1) and a 70.95 % increase in terms of energy density (35.56 Wh kg−1). Redox additive ions in the electrolyte enhance ionic conductivity and facilitate electron transfer across the porous structure of the Fe3O4/Si/GNP composite. The fast reversible kinetics of iron ions enable it to sustain decent cycle stability with a capacitance retention of 73.7 % after 1200 cycles.

Unravelling the electrochemistry of Ni-MOF derived nickel phosphide/carbon composite electrode and redox additive electrolyte for high performance supercapacitors

The performance and operation of an energy storage device are significantly influenced by the electrolyte and electrode materials. Therefore, it is crucial to develop an electrode material with a rational design and achieve compatibility with the electrolyte. In this study, we prepare Ni-MOF derived nickel phosphides/carbon (NP@C) nanostructure as an electrode for supercapacitor application. The as synthesized material provides more redox-active sites, better spatial utilization, improved conductivity, and a high-polarized surface that will speed up ion migration at electrode/electrolyte. Also, the usage of redox additive electrolyte (0.2 M K3[Fe (CN)6] in 1 M Na2SO4) further complements the redox active sites and hence the improved charge transport. Therefore, NP@C electrode achieved a remarkable 2136.3 F/g of capacitance at 3 A/g with 90.6 % of capacitance retention after 5000 charge-discharge cycles. In addition, the surface-diffusion studies confirms that NP@C shows high diffusion contribution of 82.6 % in redox electrolyte than that of 25.1 % in 1 M Na2SO4. Furthermore, NP@C//NP@C symmetric supercapacitor device in redox additive electrolyte also delivered remarkable performance rendering high energy density of 52.5 Wh/kg at a power density of 750 W/kg. In addition, NP@C//NP@C also shows the long-term stability with attenuating only 7.2 % of initial capacitance value after 10000 charge-discharge cycles. In addition to this, the device performs extremely well when tested for self-discharge studies. Hence, this study demonstrates the perfect harmony of NP@C electrodes and redox additive electrolyte to fabricate a high-performance supercapacitor.

A comprehensive study of affordable “water-in-salt” electrolytes and their properties

The search for alternative electrolytes has been extremely topical in recent years with the “water-in-salt” electrolyte, especially, lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) coming to the fore in the context of high-voltage electrolytes. However, “water-in-LiTFSI” exhibits ultra-high cost and low ionic transport when compared with the aqueous lithium-halide, -nitrate as well as -sulphate salts (quoted as LiX). This work rediscovered the properties of a “water-in-salt” (LiX electrolytes) made from a variety of concentration from 1 m to saturated conditions. The changes of physical properties e.g., viscosity, pH, conductivity, density, and temperature during mixing were then reported. The electrochemical properties of electrolyte were tested using carbon-based materials (YEC-8A) as a model system (three electrode configuration), and the finding was then expanded to a coin cell supercapacitor for benchmarking the performance per cost unit. It has been found that the use of highly concentrated LiX electrolytes does not always enhance the potential window. LiBr and LiI shown the redox properties while increasing the concentration can speed up the redox process (voltage remains unchanged). Using superconcentrated LiCl can slightly expand the potential window; however, corrosion is the main task to be addressed. Besides, voltage expansion of LiNO3 is found to be approximately 2.2 V, which is comparable to LiTFSI. The breakdown cost of the electrolyte also shows that LiTFSI exhibits the lowest energy density per cost unit (dollars), while LiNO3 provides the most feasible cost in term of power density. We then marked that the electrolytes such as LiBr and LiI can be used as redox additive electrolytes. This work also shows the fundamental insight into the physical and electrochemical properties of LiX for possible alternative use as a cheap “water-in-salt” electrolyte in energy storage apart from LiTFSI.

Nanoscale CdS enwrapped zeolite-like Zn-MOF nanocomposite for advanced energy storage systems

With reference to the promising characteristics of metal–organic frameworks (MOFs) and the contributions of nanoparticles (NPs) to their electrochemical activities, the hybrid MOF built with metal sulphides has garnered a lot of attention, primarily as electrode materials in energy storage devices. The polyhedral-shaped CdS enwrapped zeolitic imidazolate framework-8 (ZIF-8) nanocomposites have been prepared by in-situ chemical synthesis. The electrochemical performance was evaluated in 6 M KOH electrolyte, achieving a specific capacitance of 1063.48 Fg−1 at 5 mV/s. The nanocomposite electrode material exhibits good cyclic stability, with 82.32 % (6 M KOH) and 85.91 % (redox additive electrolyte) capacity retention after 6000 cycles at 5 A/g. The energy and power density of the asymmetric supercapacitor were found to be 2.81 Wh/kg and 1785.71 W/kg, respectively.

Synthesis and characterization of SnO2-La2O3 for electrochemical supercapacitor performance in redox additive electrolyte

Synthesis and characterization of SnO2-La2O3 for electrochemical supercapacitor performance in redox additive electrolyte

A High-Performance Supercapacitor Based on Hierarchical Template-Free Ni/SnO2 Nanostructures via Hydrothermal Method.

Novel flake-like Ni1-xSnxO2 particles were successfully prepared by template-free hydrothermal synthesis. The prepared samples were investigated for their properties by different characterization techniques. Scanning micrographs showed that the obtained particles consisted of nanoflakes. The X-ray diffraction results of the Ni1-xSnxO2 revealed the formation of mixed-phase Ni/SnO2 having the typical tetragonal structure of SnO2, and the cubic structure of Ni in a nanocrystalline nature. The doping with Ni had a certain influence on the host's lattice structure of SnO2 at different doping concentrations. Confirmation of the functional groups and the elements in the nanomaterials was accomplished using FTIR and EDS analyses. The electrochemical performance analysis of the prepared nanomaterials were carried out with the help of the CV, GCD, and EIS techniques. The specific capacitance of the synthesized nanomaterials with different concentrations of Ni dopant in SnO2 was analyzed at different scanning rates. Interestingly, a 5% Ni-doped SnO2 nanocomposite exhibited a maximum specific capacitance of 841.85 F g-1 at 5 mV s-1 in a 6 M KOH electrolyte. Further, to boost the electrochemical performance, a redox additive electrolyte was utilized, which exhibited a maximum specific capacitance of 2130.33 at 5 mV s-1 and an excellent capacitance retention of 93.22% after 10,000 GCD cycles. These excellent electrochemical characteristics suggest that the Ni/SnO2 nanocomposite could be utilized as an electrode material for high-performance supercapacitors.

Boosting specific capacitance: Harnessing redox-additive electrolytes for enhanced performance in activated porous carbon derived from palmyra palm leaves

Carbon materials derived from palmyra palm leaves and chemically activated with ZnCl2 exhibit remarkable energy storage characteristics. Carbon derived from leaves has a specific surface area of 1300 m2/g and provides extensive electrochemical interfaces. The leaf-derived carbon initially displays a specific capacitance of 75.60F/g at 5 mV/s in 0.1 M Na2SO4 electrolyte. Specific capacitance is significantly improved by introducing a redox additive into the parent electrolyte. In a potential window of 1 V, the combination of 0.1 M Na2SO4 and 0.03 M KI yields a specific capacitance of 173.04F/g at 5 mV/s. The findings highlight the exceptional performance and higher stability of leaf-derived activated carbon.

Mixed metal oxide-based binder-free electrode and redox additive electrolyte combination for enhanced supercapacitor performance

In this study, a novel Co3O4/CeO2 nanocomposite for supercapacitors was fabricated through a one-step hydrothermal method, to achieve distinct crystalline phases and a unique flower-like structure. Integrated into a binder-free electrode (BFE) on Ni foam, the Co3O4/CeO2@NF electrode outperformed individual Co3O4 and CeO2-based electrodes. The synergistic effect between Co3O4 and CeO2, enhances the overall surface area, porosity and conductivity of the composites, which improved the supercapacitor characteristics. Detailed analyses confirmed the Co3O4/CeO2@NF electrode's superior cyclic voltammetry, galvanostatic charge-discharge, rate capability, and stability under potassium hydroxide (KOH) and redox additive electrolytes (RAE). The incorporation of RAE further boosted the performance, showcasing the potential for advanced energy storage applications. The assembled asymmetric supercapacitor (ASC) device exhibited outstanding energy and power densities, making it promising for practical applications. Comprehensive electrochemical impedance spectroscopy (EIS) studies offered insights into charge transfer dynamics, highlighted the positive impact of redox additives. This work contributed to understand the synergistic effects in metal oxide composites on advancing the high-performance supercapacitor development.

Boosted electrochemical properties of Co3O4 nanoflakes by the addition of a redox-additive electrolyte

Abstract Metal oxide-based electrode materials and redox additive electrolytes hold great promise as essential components of energy storage devices and have a great impact on their overall performance. Co3O4 nanoflakes (NFs) have been prepared by a simple hydrothermal method. After thorough characterization of structure, functional group, and surface morphology, the potential of the as-prepared Co3O4 NFs is assessed as an electrode material for a supercapacitor. The powder XRD analysis confirms the formation of the spinel cubic phase and space group Fd 3 ‾ $\bar{3}$ m. Morphological studies showed prepared Co3O4 having nanoflakes-like structures and, with analysis by EDX, the presence of elemental composition has been confirmed. The electrochemical performance of the Co3O4 electrodes has been studied in three electrode configurations using a redox-additive electrolyte. The electrode demonstrates enhanced supercapacitor performance with a redox additive electrolyte due to the reversible oxidation states of Co2+/Co3+ and Fe2+/Fe3+, which significantly reinforced the Faradaic redox reaction. The CV curve has maintained its shape even at all scan rates, confirming the outstanding rate capability of the electrode. The Co3O4 electrode showed a greater specific capacitance (C sp) of 611.16 F g−1 at a current density of 10 A g−1 in a redox additive electrolyte solution and capacitance retentions up to 69.23 % after 10,000 cycles. The calculated charge transfer resistance (R ct ) of before and after GCD 10,000 cycles is obtained. The overall performance of the electrode material being consider as a promising candidate for supercapacitor applications.

Significant improvement of the electrochemical performance of nanoscale Zinc vanadate as an electrode material for supercapacitors via redox additive electrolytes

Nanostructured Zinc vanadate (Zn3(VO4)2) has been successfully synthesised via a simple and low-cost co-precipitation route. The Zn3(VO4)2 nanoparticles (NPs) possess a specific capacitance of 83.83 F/g at a current density of 1 A/g in 6 M KOH. Remarkably, the working electrode shows an excellent specific capacitance of 869.87 F/g in K3[Fe(CN)6] redox additive electrolytes (RAE). Moreover, the fabricated asymmetric supercapacitor (ASC) achieved 3.626 Wh/kg energy density and 3125 W/kg power density.

Redox additive effects on the electrochemical performance of hydrothermally grown, binder-free CuO nanosheets in aqueous electrolytes

Adding redox additives into the traditional electrolytes is an efficient approach to achieving high-performance binary metal oxide electrode-based supercapacitors (SCs). Herein, binder-free CuO nanosheets are developed on nickel foams via a facile hydrothermal approach, and their charge storage performance in K3[Fe(CN)6] (KFCN) redox additive electrolyte is investigated. In a three-terminal (3T) configuration, the as-prepared electrode demonstrates a remarkable capacitance of 2755 mF cm−2 (2296 F g−1) in KFCN redox additive electrolyte, which is 10 times greater than that obtained in bare KOH electrolyte (266 mF cm−2 or 222 F g−1). Further, the 93 % capacitance retention after 2000 cyclic voltammetry cycles confirms the reasonable stability of the CuO electrode for SCs with redox additives electrolyte. Additionally, the assembled CuO electrodes-based solid state symmetric supercapacitor (SSC) with redox additive gel electrolyte achieves a maximum energy density (Es) of 31.5 Wh kg−1 at a power density (Ps) of 500 W kg−1. Furthermore, red LEDs are operated by the power source of two SSCs connected in the serial mode for 130 sec. This studies imply that utilizing CuO within redox additive electrolytes could present a simple and cost-effective approach for developing high-energy storage supercapacitors.

Ultrahigh capacitive performance of O andMgself‐dual‐doped activated carbon fromAnanas comosusleaf fiber using a redox additive‐based electrolyte

AbstractBACKGROUNDThe capacitive behavior of a supercapacitor (SC) based on activated carbon derived from biomass is enhanced when a halogenated iodide (in this case, iodide, Iˉ) is added to the acidic aqueous electrolyte. In this work, we prepared ultrahigh capacitive performance of O and Mg self‐dual‐doped activated carbon (AC) fromAnanas comosusleaf fiber (ACLF) via chemical activation at high temperature, followed by activation under the protection of CO2to produce commercially feasible electrodes for commercial‐scale SC devices. The prepared ACLFs were characterized through SEM–EDX, XRD, adsorption/desorption of N2. Moreover, in a 2‐electrode setup, the capacitive activity of the prepared ACLFs were evaluated using cyclic voltammetry and galvanostatic charge/discharge techniques in a redox additive electrolyte (1 M H2SO4 + 0.05 M KI).RESULTThe pairs 3Iˉ/I3ˉ, 2Iˉ/I2, 2I3ˉ/3I2, and I2/IO3ˉ generate reduction–oxidation (redox) peaks in the CV curves and a significant Faradaic plateau in the GCD curves. The ACLF samples delivered an outstanding gravimetric capacitance and energy density as high as 581 F g−1and 80.69 Wh kg−1at a power density of 346.14 W kg−1, respectively.CONCLUSIONThe enhanced capacitive activity is a result of the Faradaic pseudocapacitance associated with the redox‐active ions present in the acidic electrolyte solution. This work describes a facile and economical approach to acquiring a potential candidate of electrode materials for SC devices with exceptional performance, achieved via a redox additive‐based electrolyte system. © 2023 Society of Chemical Industry (SCI).

Redox Additive Electrolyte Study of Metal-Organic Framework Derived Nickel Phosphide/Carbon Composite for Supercapacitors

The performance and operation of an energy storage device are significantly influenced by the electrolyte and electrode materials. Therefore, it is crucial to create an electrode material with a rational design and ensure that it is compatible with the electrolyte. In this study, we prepare nickel phosphides/carbon (NP@C) nanostructure from Nickel metal-organic framework (Ni-MOF) using one-step phosphidation technique for supercapacitor applications. This method aims to produce a distinctive structure with more redox-active sites as well as improved conductivity and a high-polarized surface that will speed up ion migration between the electrolyte and the surface. In order to further enhance the redox additive sites and thus the charge transport, we have employed redox additive electrolyte (0.2M K3[Fe(CN)6] in 1M Na2SO4). Using three electrode electrochemical system, NP@C electrode obtained a phenomenal specific capacitance of 2136.3 F/g at 3A/g with a specific capacitance retention rate of 90.6% after 5000 cycles. Furthermore, a symmetric supercapacitor device is assembled using two NP@C electrodes and redox additive electrolyte that renders a high energy density of 52.5 Wh/kg at a power density of 750 W/kg along with a long cycle life of ~93% after 10000 cycles. Hence, this study demonstrates how NP@C and redox additive electrolyte work in perfect harmony to generate a high-performance supercapacitor.

Enhanced electrochemical performance of fabricated asymmetric supercapacitor in redox additive electrolyte

The present investigation reported the solvothermal synthesis of pristine Zeolitic Imidazolate Framework-8 (ZIF-8) as an electrode for the fabrication of energy conversion and storage devices (two-electrode assembly named as ECSDs) in redox-additive (0.35 M K4(Fe(CN)6).3H2O in 6 M NaOH) electrolyte (RAE). The synthesized electrode was characterized and compared utilizing Brunauer–Emmett–Teller (BET), X-Ray Diffraction (XRD), High-Resolution Transmission Electron Microscopy (HRTEM), and Scanning Electron Microscopy (SEM) analysis for porosity differences, specific surface area (SSA), structural, crystallinity, and hexagonal morphology. The prepared bare ZIF-8 coupled with activated carbon (ZIF-8//AC) to evaluate the specific capacity (Cs = 256 C/g at 32 A/g), energy (ED) density, and power density (PD), known as asymmetric supercapacitor (ASSC) device. In the wide (0.0–2.1 V) potential window, the device could reach a maximum PD of 30,001.5 W/kg (for the ED of 66.67 Wh/kg at 60 A/g) and a maximum ED of 142.22 Wh/kg (for the PD of 15999.75 W/kg at 32 A/g). Furthermore, at 50 A/g (ultrahigh current density), the device exhibited outstanding cyclic stability (86.5 %) and columbic efficiency (88 %) up to 6000 galvanostatic charge-discharge (GCD) cycles. Our examination indicated that the prepared ZIF-8 presented immense potential for the practical utility of ECSDs by lightning green (∼13 min) and red (∼8 min) light-emitting diodes (LEDs).