Material For Supercapacitor Applications Research Articles

Freestanding vanadium nitride nanowire/nitrogen-doped graphene paper with hierarchical pore structure for asymmetric supercapacitor anode

Vanadium nitride (VN) is a promising anode material for asymmetric supercapacitors (ASCs) owing to its high theoretical pseudocapacitance and high electrical conductivity. However, the instability of VN in aqueous electrolytes hinders practical applications. In this study, VN nanowires (VNNWs) were hybridized with nitrogen-doped graphene (NG) to fabricate a freestanding VNNW/NG porous paper electrode. The prepared paper electrode exhibited excellent electrochemical performance with an outstanding specific capacitance of 244.7 F·g−1 at 0.5 A·g−1 and a rate capability of 70.7% capacitance retention as the current density increased from 1 to 10 A·g−1. Moreover, the VNNW/NG anode presented remarkable cycling stability of 87% capacitance retention over 10,000 cycles at 5 A·g−1. Encapsulation with NG significantly improved the stability of VNNWs, overcoming their major drawbacks (i.e., low cycling stability). Also, the hierarchical pore structure of the VNNG/NG could facilitate high energy and power density capabilities. An ASC assembled with VNNW/NG anode and nickel oxide/reduced graphene oxide (NiO/rGO) cathode presented high energy density of 20.2 Wh·kg−1 at power density of 850.0 W·kg−1. Thus, we suggest that the design strategy of the fabricated porous paper electrode could be utilized to produce high-performance anode materials for application in supercapacitors.

Structural Elucidation of Nitrogen-Doped Reduced Graphene Oxide/Hausmannite Manganese Oxide Nanocomposite for Supercapacitor Applications

The increasing consumption of fossils fuel accompanied by related carbon emissions and complex set of issues associated with the generation and use of electricity has raised an urgent need for reliable, renewable and sustainable energy alternatives [1]. Nanotechnology and the production of nanostructured materials has driven the rapid growth in the research of carbon nanomaterials as energy storage materials for supercapacitor (SCs) applications. Among several carbon nanomaterials explored for SCs, graphene has shown to be the leading carbon nanomaterial, due to its intriguing properties such as highly tunable surface area, outstanding electrical conductivity, good chemical stability and excellent mechanical behavior [2]. Due to challenges in the bulk synthesis of graphene, reduced graphene oxide (rGO) has been opted as the preferred choice for the development of SC devices. Transition metal oxides also gained much interest in various research industries as materials for SCs applications. Among transition metal oxides, manganese oxide, MnxOy, appeared to be the promising electrode material due to its interesting properties such as cost effectiveness, high theoretical specific capacitance, high theoretical surface area (≥ 1370 m2 g-1), and excellent electrochemical reversibility. However, the poor conductivity of manganese oxide restricts its progress in SC applications [2, 3]. Therefore, great attention has been devoted to the improvement of the electronic properties of manganese oxides-based electrode materials by decorating them on highly conductive carbon-based nanomaterials. Although intensive study has been done on carbon nanomaterials integrated with MnxOy for pseudocapacitors, there is still less literature on the use of Mn3O4 nanoparticles decorated on carbon materials for application in SCsThis work presents a hydrothermal synthesis of the nitrogen-doped reduced graphene oxide/hausmannite manganese oxide (N-rGO/Mn3O4) nanohybrid which showed a great electrochemical performance such as high specific capacitance of 345 F g-1 and a maximum of specific energy of 12.0 Wh kg-1 (current density: 0.1 A g−1), and a maximum specific power of 22.5 kW kg-1 (current density: 10.0 A g−1) in a symmetric configuration. The nanohybrid further showed excellent supercapacitor performance in an asymmetric configuration, with the maximum specific energy and power reaching 34.6 Wh kg−1 (0.1 A g−1) and 14.01 kW kg−1 (10.0 A g−1) respectively. The results obtained affirm the use of N-rGO/Mn3O4 as a potential electrode material for high energy and power supercapacitor devices that can be commercially competitive to that of rechargeable batteries.

Electrochemical Characterizations of Ternary MnO2/Cus/Rgo Materials for Supercapacitor Applications

Supercapacitors are considered as a new class of energy storage device because of their high power density, environmentally friendliness, long cycleability, and flexible design capabilities. MnO2 and CuS have been found to be promising for supercapacitor applications because of their low cost, abundance in nature, and are environmentally friendly. Besides this, reduced graphene oxide emerged as most promising carbon materials for energy storage applications because of its high specific surface area, good electrical conductivity, and ability to attach metal oxide withoutany agglomeration. Recently, it has been reported that ternary nanocomposites have superior electrochemical performances because of their synergistic effect, which help to enhance the charge movement within the electrode material. We already reported that the specific capacitance of CuS and MnO2 as 158 F/g and 300 F/g at current densities of 0.5 A/g, respectively [1,2]. In this work we have synthesized MnO2/CuS/rGO ternary nanocomposite by hydrothermal method. The physical characterization of the synthesized materials was carried out using X-Ray diffraction, scanning electron microscopy, differential scanning calorimetry(DSC), and thermogravimetric analysis (TGA). All electrochemical measurements were conducted in standard three-electrode configuration, using a platinum wire, Ag/AgCl, and MnO2/CuS/rGO as a counter, reference, and working electrode, respectively. The results related to physical characterization, specific capacitance, cycleability, and energy density will be presented.Reference: Rahul Singhal, David Thorne, Peter K. LeMaire, Xavier Martinez, Chen Zhao, Ram K. Gupta, David Uhl, Ellen Scanley, Christine C. Broadbridgeand Rakesh K. Sharma, AIP Advances 10, (2020) 035307; https://doi.org/10.1063/1.5132713. Rahul Singhal, Justin Fagnoni, David Thorne, Peter K. LeMaire, Xavier Martinez, Chen Zhao, Ram K. Gupta, David Uhl, Ellen Scanley, Christine C. Broadbridge, Mani Manivannan, MRS Advances, 4 (13) 777-782 (2019), https://doi.org/10.1557/adv.2019.86

MnO2-graphene based composites for supercapacitors: Synthesis, performance and prospects

Supercapacitors stand out among some traditional energy storage devices due to their advantages such as long cycle stability, fast charge-discharge performance and high-power density. Therefore, it is necessary to explore high-performance electrode materials for application in supercapacitors. Manganese dioxide (MnO 2 ) has high theoretical capacitance and high energy density, however, the deterioration of volume expansion and low conductivity directly affect its wide application. Graphene has attracted great interest owing to its invention. The combination of graphene and MnO 2 can not only highlight the low resistance, large specific surface area and thermal stability of graphene, but also solve the shortcomings of MnO 2 alone as an electrode material. The proposal of composite materials has also promoted the development and application of electrode materials in supercapacitors. Hence, this review aims to summarize the synthetic strategies and research progress of MnO 2 -graphene based multi-element composites, including the combination of MnO 2 -graphene with various carbon materials, transition metal oxides and conducting polymers, respectively. Finally, the possible development directions of MnO 2 -graphene based composite electrode materials in the future are also prospected. • Focusing on the synthesis strategy and electrochemical performance. • Multi-composites exert synergistic effects and offer significant performance. • MnO 2 -graphene based composites still have a promising future in other fields.

Recent advances in bio-based electrode materials in supercapacitor applications: Energy storage materials and technologies

The modern world's reliance on fossil fuels has led to many issues, including rising fuel prices, pollution, climate change, and geopolitical unrest. While massive effort is required to deal with climate change comprehensively. Developing alternative energy sources and storage technologies is an important priority that can only be gained over time by reducing these issues. Because of this, recent years have seen an increase in the use of high-power and high-energy density storage systems, increasing the use of renewable energy sources or improving transportation efficiency contribute to climate change mitigation. Renewable energy resource deployment is associated with storage systems for reliable and continuous energy supply. It is essential to keep developing more efficient storage units to advance environmentally friendly technologies. Despite extensive research and development efforts, an essential upsurge in energy storage capability is required to meet future demand. In the next generation of energy storage devices, supercapacitors (SCs) seem an excellent candidate for wearable and portable electronics compared to the flexible lithium-ion batteries-based technologies. Electrochemically excellent carbon materials are required to protect the environment and develop renewable energy sources, but they are scarce. Depending on the desired carbon morphology, there are many different types of biomasses and biowaste materials from which to choose carbon precursors. The preparatory work and characterization of newly found and evolved bio-based carbon sources are discussed and summarized in this study. Precursor and nanostructure types are listed in alphabetical order. New carbon precursors with excellent electrochemical performance in energy storage applications are also discussed. Ultimately, a conclusion and an outlook from the application perspective are drawn.

Recent advances in bio-based electrode materials in supercapacitor applications: Energy storage materials and technologies

The modern world's reliance on fossil fuels has led to many issues, including rising fuel prices, pollution, climate change, and geopolitical unrest. While massive effort is required to deal with climate change comprehensively. Developing alternative energy sources and storage technologies is an important priority that can only be gained over time by reducing these issues. Because of this, recent years have seen an increase in the use of high-power and high-energy density storage systems, increasing the use of renewable energy sources or improving transportation efficiency contribute to climate change mitigation. Renewable energy resource deployment is associated with storage systems for reliable and continuous energy supply. It is essential to keep developing more efficient storage units to advance environmentally friendly technologies. Despite extensive research and development efforts, an essential upsurge in energy storage capability is required to meet future demand. In the next generation of energy storage devices, supercapacitors (SCs) seem an excellent candidate for wearable and portable electronics compared to the flexible lithium-ion batteries-based technologies. Electrochemically excellent carbon materials are required to protect the environment and develop renewable energy sources, but they are scarce. Depending on the desired carbon morphology, there are many different types of biomasses and biowaste materials from which to choose carbon precursors. The preparatory work and characterization of newly found and evolved bio-based carbon sources are discussed and summarized in this study. Precursor and nanostructure types are listed in alphabetical order. New carbon precursors with excellent electrochemical performance in energy storage applications are also discussed. Ultimately, a conclusion and an outlook from the application perspective are drawn.

Recent advances in bio-based electrode materials in supercapacitor applications: Energy storage materials and technologies

The modern world's reliance on fossil fuels has led to many issues, including rising fuel prices, pollution, climate change, and geopolitical unrest. While massive effort is required to deal with climate change comprehensively. Developing alternative energy sources and storage technologies is an important priority that can only be gained over time by reducing these issues. Because of this, recent years have seen an increase in the use of high-power and high-energy density storage systems, increasing the use of renewable energy sources or improving transportation efficiency contribute to climate change mitigation. Renewable energy resource deployment is associated with storage systems for reliable and continuous energy supply. It is essential to keep developing more efficient storage units to advance environmentally friendly technologies. Despite extensive research and development efforts, an essential upsurge in energy storage capability is required to meet future demand. In the next generation of energy storage devices, supercapacitors (SCs) seem an excellent candidate for wearable and portable electronics compared to the flexible lithium-ion batteries-based technologies. Electrochemically excellent carbon materials are required to protect the environment and develop renewable energy sources, but they are scarce. Depending on the desired carbon morphology, there are many different types of biomasses and biowaste materials from which to choose carbon precursors. The preparatory work and characterization of newly found and evolved bio-based carbon sources are discussed and summarized in this study. Precursor and nanostructure types are listed in alphabetical order. New carbon precursors with excellent electrochemical performance in energy storage applications are also discussed. Ultimately, a conclusion and an outlook from the application perspective are drawn.

Performance Studies of Biomass Derived RHAC and MgO Nanocomposite Electrode Materials for Supercapacitor Applications

The electrode materials for supercapacitors based on biomass-produced Rice Husk Activated Carbon (RHAC) and RHAC+50% MgO nanocomposite are compared in this article. The crystallinity, structural morphology, and crystalline size of the particles were determined using microstructural and electrochemical characterization. Scanning Electron Microscope and X-Ray Diffraction techniques were used to determine the surface morphology and crystallinity of the materials. The XRD results reveal that RHAC which has broad peaks indicates amorphous nature whereas RHAC+50% MgO nanocomposite which has sharp peaks exhibits crystalline nature. The RHAC+50% MgO nanocomposite electrode exhibits a specific capacitance of 220.52 F/g however RHAC electrode exhibited only 162.91 F/g at a scan rate of 2mV/s by Cyclic Voltammetry in 1 M KOH electrolyte. After 2500 cycles of Galvanic charge-discharge, it was discovered that RHAC+50% MgO nanocomposite has capacitance retention of 76.71% and RHAC has capacitance retention of 80.49%.

Effect of annealing time on the structural, morphological, optical and electrical properties of NiS thin films

In this work, we prepared thin films of nickel sulfide by spray pyrolysis on substrates of the glass at temperature of 300°C. The solution used is a mixture of nickel acetate and thiourea as a source of nickel and sulfur respectively, acetic acid was used as a complexing agent, and then heated the resulting layers in an ordinary furnace at 300°C at different times of 1h, 2h and 3h to study the annealing time effect on the physical and chemical properties. The characterization methods used indicate remarkable changes in the structural, electrical, morphological and optical properties of NiS films under annealing time. The results obtained have shown that the prepared NiS films contain good crystallization, dense morphology, good stochiometric ratio and high conductivity, and these specifications make them a potential candidate as electrode material for application in super-capacitors.

Formation of fringed carnation-like cobalt manganese fluoride hydroxide assisted by ammonium fluoride for supercapacitor applications

The binary transition metal oxides or hydroxides have received significant attention as potential materials in supercapacitor applications owing to their unique characteristics. In this study, a binary cobalt-manganese fluoride hydroxide-CoMn(OH)F is assembled successfully through the crucial assistance of an ammonium fluoride agent in an alkali source of hexamethylenetetramine (HMTA). At a rational design, the CoMn(OH)F with fringed carnation-like morphology obtains a specific capacitance of 541 F g −1 (at a current density of 1 A g −1 ) in a three-electrode system and cycling stability of 84% after 15,000 cycles. Furthermore, an asymmetric device CoMn(OH)F//activated carbon in a two-electrode system not only exhibits a remarkable specific capacitance of 135 F g −1 (at 0.4 A g −1 ), a high energy density of 39 Wh kg −1 , and a power density of 3.65 kW kg −1 but also maintains 91% of the initial capacitance after 10,000 cycling tests. These electrochemical performances demonstrate the considerable potential of the fluoride hydroxide CoMn(OH)F for supercapacitor applications. • CoMn(OH)F was formed via the key role of NH 4 F and the optimal precursor ratio. • CoMn(OH)F had a fringed carnation-like morphology. • Sample obtained synergistic effects of diffusion and capacitive-controlled process. • CoMn(OH)F//AC exhibited energy density 39 Wh kg −1 and power density 3.65 kW kg −1 .

A Blockwall‐Type Layered Bis(dithiolato)nickelate Radical Salt Exhibiting High‐ and Two‐Dimensional Antiferromagnetic Coupling Feature

Comprehensive SummaryThe family of [M(dmit)2]‐ salts (dmit2‐ = 2‐thioxo‐1,3‐dithiole‐4,5‐dithiolate; M = Ni, Pd and Pt) generally show novel magnetic, electric, magnetoelectric and photoelectric properties. Herein, a blockwall‐type layered [Me3S][Ni(dmit)2] radical salt (1; Me3S+ = trimethylsulfonium) was prepared and characterized by microanalysis, IR spectroscopy, thermal analysis, powder and single crystal X‐ray diffraction techniques. Salt 1 crystalizes in triclinic space group P‐1, with two pairs of [Ni(dmit)2]‐ and Me3S+ ions in an asymmetric unit. The anions form blockwall‐type monolayer, being parallel to crystallographic (0 1 1) plane, and the cations are accommodated in the spaces of anion monolayer. Salt 1 features a two‐dimensional S = ½ antiferromagnetic (AFM) spin system with θ = ‐97.8(1) K and a semiconductor with σ ≈ 10‐4 S·cm‐1 and activation energy Ea = 0.24(1) eV in 308—368 K. 1 shows two‐step dielectric relaxations ranged from 173—373 K and 1—107 Hz for the dipole motions of two different polar cations. Most importantly, the dielectric constant of 1 reaches to ~17, with high‐κ nature. This study suggests the possibility of achieving high‐κ materials by introducing polar and low rotation barrier components into van der Waals crystal and high‐κ [Ni(dmit)2]‐‐based electrode materials for applications in supercapacitors.

Surfactant Free Synthesis of Mn3o4 Nanoparticles Embedded on Nano Rods as an Electrode Material for Supercapacitor Application

Surfactant Free Synthesis of Mn3o4 Nanoparticles Embedded on Nano Rods as an Electrode Material for Supercapacitor Application

Supercapacitor applications of 2_aminoisobutyric acid-mediated N-doped graphene

N-doped graphene has been synthesized by the reduction of graphene oxide (GO) using 2-aminoisobutyric acid (AIB) as a reducing agent (N-GrAIB) under mild experimental conditions in aqueous medium. The reduction of GO was indicated by a change in its optical absorption as well as by its Raman spectrum and 13C solid state magic angle spinning (MAS) nuclear magnetic resonance (NMR) studies. The latter two techniques also confirmed the doping of N. N-GrAIB exhibited fairly high conductivity (6.3 S/cm), high specific capacitance (228 F/g at 1 A/g) with good cycling stability for 1000 charge-discharge cycles, high coulombic efficiency (100-101%) and high energy density of 20.26 Wh/kg at a power density of 400 W/kg. The present work shows that this environmental benign N-doped graphene (N-GrAIB) could be a promising electrode material for supercapacitor applications. Copyright © 2016 VBRI Press

Synthesis and characterization of Cu0.92Co2.08O4 nanoplates for supercapacitor electrode application

In this endeavor, the Cu0.92Co2.08O4 materials were prepared by CTAB assisted hydrothermal technique with calcination process. The cyclic voltammetric analysis exhibit the specific capacitance of 543 Fg−1 at a scan rate of 5 mVs−1 whereas the galvanostatic charge/discharge studies provide the specific capacitance of 489 Fg−1 at a current density of 1 Ag−1. The Cu0.92Co2.08O4 nanoplate possesses low internal and charge discharge resistance which exhibit 93% of initial capacitance after 2000 continuous cyclic voltammetric cycles at a scan rate of 100 mVs−1. These results indicate that the prepared Cu0.92Co2.08O4 nanoplate is the significant electrode material for supercapacitor application.

Ultrahigh‐areal‐capacitance aqueous supercapacitors enabled by soft biomass‐derived porous carbon membrane

Sustainable biomass-derived carbons in powdery forms have shown to be high-performance capacitive electrode materials for application in supercapacitors (SCs) due to their large specific surface area, distinct porous structure, and low cost; however, their practical applications are being largely hampered due to their powdery status-related issues including tedious electrode assembly process and insufficient capacitance and cycling stability. Herein, we develop a porous carbon membrane, termed as PECM, by direct carbonization of Pleurotus eryngii (PE) using KOH as activator. The as-fabricated PECM features a hierarchically nanostructure with high porosity, large specific surface area, and excellent electrolyte wettability, which cannot only afford a large usable active area for the interfacial adsorption of electrolyte ions but also supply fast diffusion pathways for electrolyte ions. Moreover, the as-fabricated PECM is doped with N and also has large amounts of O, S, and P-containing functional groups, which would be expected to contribute additional pseudocapacitance. More importantly, the as-fabricated PECM has excellent mechanical performance and can be directly used to assembly an aqueous symmetric SC device. Attributing to the above structural merits of PECM, the two-electrode symmetric SC assembled using two identical PECM-800 electrodes (~20 mg cm−2 for each electrode), exhibits excellent electrochemical performance with ultrahigh areal capacitance (4.6 F cm−2 at 10 mA cm−2), excellent long-term cycling stability (113% capacitance retention after 20 000 cycles), and superior energy densities of 0.24 to 0.09 mWh cm−2 at power densities of 5.20 to 51.9 mW cm−2. This work offers a new insight on employing biomass to prepare value-added and practically applicable carbon materials for the application in SCs.

Laser synthesis of superhydrophilic O/S co-doped porous graphene derived from sodium lignosulfonate for enhanced microsupercapacitors

Porous graphene with rational heteroatoms doping has been widely researched as one of the most prominent materials for application in supercapacitors. Herein, we implement a green and facile laser engraving strategy to synthesize three-dimensional (3D) superhydrophilic and oxygen (O)-sulfur (S) co-doped porous graphene electrodes. Specifically, the mixed sodium lignosulfonate slurry is evenly coated on the laser-induced graphene (LIG) interdigital electrodes, and followed by a duplicated laser scribing process. The as-prepared materials can synchronously possess hierarchical porous graphene architectures, superior hydrophilicity, and O/S co-doped chemistry properties, which can significantly promote the penetration and transport of electrolyte ions and provide extra pseudocapacitance. Benefiting from these advantages, satisfactory capacitive performance of the assembled MSCs is obtained, such as an outstanding areal capacitance of 53.2 mF cm−2@0.08 mA cm−2, which is about 39 times larger than of undoped MSC. Moreover, remarkable mechanical flexibility, excellent modular integration capability as well as good cycling stability (81.3% capacitance retention after 8000 cycles) have been also achieved. As such, this study offers a novel and efficient strategy for valuable utilization of biomass lignosulfonate, and the as-prepared heteroatom-doped superhydrophilic porous graphene holds enormous promise for high-performance energy storage devices.

MnO2@polypyrrole composite with hollow microsphere structure for electrode material of supercapacitors

In this work, a new MnO2@polypyrrole mesoporous composite with hollow microsphere structure is synthesized using PS (polystyrene) beads as the hard template. In 1 M Na2SO4 solution, it exhibits a specific capacitance value of 295F g−1 at the current density of 1 A g−1. After 20,000 charge/discharge cycles at the current density of 10 A g−1, the capacitance retention rate is 100%. The MnO2@H-PPy (1:4)-based asymmetric supercapacitor shows a specific capacitance of 63F g−1 in a potential window of 0 to + 2.2 V at the current density of 1 A g−1. The energy density is 42 Wh kg−1 and the power density is 1100 W kg−1, which proved to be a promising candidate for the electrode materials in supercapacitor applications.

Understanding the impact of nitrogen doping and/or amine functionalization of reduced graphene oxide via hydrothermal routes for supercapacitor applications

Nitrogen doping and amine-functionalization have previously been used to improve the capacitance of graphene-based materials, however there is a lack of understanding on the mechanisms by which these modifications impact the electrochemical behavior and electrochemical supercapacitor performance, or if these approaches can be combined to achieve synergistic benefits. Herein, we investigate this by synthesizing reduced graphene oxide (HtrGO) with varying degrees of nitrogen-doping (N-HtrGO), amine-functionalization (NH3+-HtrGO), and a hybrid amine-functionalization and nitrogen-doping (N-NH3+-HtrGO). Synthesized materials were systemically investigated to show the effect of nitrogen-doping and amine-functionalization using electrochemical characterization and rigorous physico-chemical analysis. The capacitance performance was increased in the order of NH3+-HtrGO < HtrGO < N-NH3+-HtrGO < N-HtrGO. The highest capacitance of 244 F/g was observed at 50 mV/s for N-HtrGO. The specific capacitances of NH3+-HtrGO was limited to 179 F/g at 50 mV/s, indicating graphene sheet restacking likely due to interactions between positively charged amine species and oxygen functional groups. Interestingly, the capacitance of N-NH3+-HtrGO was significantly higher as compared to that of NH3+-HtrGO, which was attributed to less agglomeration of GO due to deoxygenation through nitrogen-doping. This work provides fundamental understanding towards nitrogen-based modification of graphene materials and the impact on electrochemical properties that will guide the design of new materials for supercapacitor applications.

Synthesis of biomass-derived carbon aerogel/MnOx composite as electrode material for high-performance supercapacitors

Synthesis of economical and high-performance carbon materials from biomass has been seen as an emerging strategy for energy storage devices. In this work, using radish as the raw material, a facile method for the synthesis of 3D carbon aerogels incorporated with MnOx nanoparticles has been developed. At a suitable impregnation amount of Mn(NO3)2, MnOx nanoparticles with a diameter of around 110 nm grow uniformly on the surface of the carbon aerogel, during which ordered carbon structures can be formed and results in an increase in the graphitization degree. The cross-linked 3D dimensional carbon structure and uniform growth of MnOx nanoparticles are beneficial to the electrochemical performance of the carbon aerogel/MnOx composite as electrode materials in supercapacitor applications. The carbon aerogel/MnOx composite impregnated with 1.6 mmol Mn(NO3)2 and activated under CO2 atmosphere (CAC@MnOx-1.6) reached the highest gravimetric specific capacitance of 557 F g−1 at a current density of 1 A g−1 in the three-electrode system using 2 M KOH as the electrolyte. In a two-electrode system, a high gravimetric specific capacitance of 447 F g−1 was obtained using the CAC@MnOx-1.6-based electrode, and the power density reached 4786.44 W kg−1 at an energy density of 248.23 Wh kg−1 with a current density of 1 A g−1 in the voltage range of -1~1 V.

Graphene quantum dots decorated on spinel nickel cobaltite nanocomposites for boosting supercapacitor electrode material performance

Composites of transition metal oxides, with carbon, have been considered to be appropriate materials for enhancing their electrochemical properties in supercapacitor applications. In this study, we prepare Nickel-Cobaltite/ Graphene Quantum Dots (NiCo2O4/GQDs) composite structures that exhibit improved electrical conductivity and function as electrode materials with higher energy density in comparison to GQDs and NiCo2O4. The electrochemical performance of NiCo2O4/GQDs is confirmed through galvanostatic charge–discharge method for three electrode systems with an electrolyte of 0.1 M potassium hydroxide. The observed specific capacitance for the fabricated composite has been found to be 481.4 Fg−1 at 0.35Ag−1. It is higher than that of Graphene Quantum Dots (Csp~45.6 Fg−1). This is due to the enhancement in the electrical conductivity and diffusion of ions which become faster between electrodes and electrolyte. These findings demonstrate the unique characteristics of the fabricated composites as superior electrode materials for applications in supercapacitors.