High-performance Supercapacitor Applications Research Articles

Facile Synthesis of Biocarbon-Based MoS2 Composite for High-Performance Supercapacitor Application.

Nanocomposites are gaining high demand for the development of next-generation energy storage devices because of their eco-friendly and cost-effective natures. However, their short-term energy retainability and marginal stability are regarded as hindrances to overcome. In this work, we demonstrate a high-performance supercapacitor fabricated by biocarbon-based MoS2 (Bio-C/MoS2) nanoparticles synthesized by a facile hydrothermal approach using date fruits. Here, we report the high specific capacitance for a carbon-based nanocomposite employing the pyrolysis technique of converting agricultural biowaste into a highly affordable energy resource. The biocompatible Bio-C/MoS2 nanospheres exhibited a high capacitance of 945 F g–1 at a current density of 0.5 A g–1 and an excellent reproducing stability of 92% after 10000 charge/discharge cycles. In addition, the Bio-C/MoS2 NS showed an exceptional power density of 3800–8000 W kg–1 and an energy density of 74.9–157 Wh kg–1. The results would pave a new strategy for design of eco-friendly materials toward the high-performance energy storage technology.

Facile synthesis of novel poly(1H-benzoindole)/WO3 nanocomposites with enhanced energy storage capability and its application in high-performance supercapacitor

• Novel PBIn/WO 3 composites show good energy storage performance due to the synergistic effect of PBIn and WO 3 . • Asymmetric supercapacitor based on PBIn/WO 3 nanocomposites and PEDOT is constructed. • Supercapacitor shows high specific capacitance (122.25F g −1 ) and cycling stability (81.6% after 3000 cycles). Poly(1H-benzindole)/tungsten trioxide (PBIn/WO 3 ) nanocomposites are successfully prepared by simple hydrothermal synthesis and electrochemical polymerization. There is a synergistic effect in PBIn and WO 3 , which can enhance the electrochemical performance and make use of their respective performance advantages to make up for each other’s deficiencies. Among them, there is also good energy level matching, which can provide a favorable driving force for charge transfer. Moreover, the capacitive performance and electron migration rate of the composite material are enhanced due to the good electrical conductivity and charge storage capacity of PBIn. Hence, the PBIn/WO 3 nanocomposites possess a specific capacitance as high as 535.5F g −1 and enhanced charge transfer rate. Asymmetric supercapacitor devices based on PBIn/WO 3 nanocomposites and poly(3,4-ethylenedioxythiophene) (PEDOT) are successfully constructed, which show good specific capacitance (122.25F g −1 ) and cycling stability (81.6 % retention after 3000 cycles). The device exhibits maximum energy density of 38.2 Wh kg −1 and maximum power density of 966.7 W kg −1 . In the future field of energy storage, the PBIn/WO 3 nanocomposites prepared in this study may have broad application prospects.

Binder-free vertical graphene nanosheets templated NiO petals for high-performance supercapacitor applications

Transition metal oxide and carbon-based hybrid nanostructures with high charge capacity and rate capabilities are emerging as promising electrodes for commercial supercapacitor devices. Herein, we report the fabrication of binder-free supercapacitor electrodes of vertical graphene nanosheets (VGN) templated NiO petals. The NiO petals are grown under different background O2 pressure, deposition temperature, and the number of laser shots using pulsed laser deposition (PLD). The morphology, microstructure, and stoichiometry of the NiO petals are greatly influenced by the background O2 pressure and deposition temperature. The increase in deposition temperature has been found to increase the particle size, whereas the number of laser shots affected the morphology and stoichiometry. Further, the VGN templated growth facilitates the NiO to possess a high surface area and, in turn, results in ∼2.5 times higher areal capacitance than the NiO directly grown on carbon paper substrate without VGN. In the present study, the VGN templated NiO petals exhibited areal capacitance as high as 175 mF/cm2 @ 0.1 V/s. The high areal capacitance is correlated with morphology, microstructure, particle size, and mass loading. An asymmetric coin cell device fabricated using NiO/VGN hybrid and oxygenated VGN electrodes exhibited energy and power densities of 0.4 μWh/cm2 and 102 μW/cm2, respectively. Further, LED lighting using the coin cell reveals the potential utilization of NiO/VGN hybrid electrodes for commercial applications.

Electrospun Benzimidazole-Based Polyimide Membrane for Supercapacitor Applications.

A benzimidazole-containing diamine monomer was prepared via a simple one-step synthesis process. A two-step procedure involving polycondensation in the presence of aromatic dianhydrides (4,4′-oxydiphthalic anhydride, ODPA) followed by thermal imidization was then performed to prepare a benzimidazole-based polyimide (BI-PI). BI-PI membranes were fabricated using an electrospinning technique and were hot pressed for 30 min at 200 °C under a pressure of 50 kgf /cm2. Finally, the hot-pressed membranes were assembled into supercapacitors, utilizing high-porosity-activated water chestnut shell biochar as the active material. The TGA results showed that the BI-PI polymer produced in the two-step synthesis process had a high thermal stability (Td5% = 527 °C). Moreover, the hot-press process reduced the pore size in the BI-PI membrane and improved the pore-size uniformity. The hot-press procedure additionally improved the mechanical properties of the BI-PI membrane, resulting in a high tensile modulus of 783 MPa and a tensile strength of 34.8 MPa. The cyclic voltammetry test results showed that the membrane had a specific capacitance of 121 F/g and a capacitance retention of 77%. By contrast, a commercial cellulose separator showed a specific capacitance value of 107 F/g and a capacitance retention of 49% under the same scanning conditions. Finally, the membrane showed both a small equivalent series resistance (Rs) and a small interfacial resistance (Rct). Overall, the results showed that the BI-PI membrane has significant potential as a separator for high-performance supercapacitor applications.

Facile preparation of SnS2 nanoflowers and nanoplates for the application of high-performance hybrid supercapacitors

In this work, the SnS2 nanoflowers (SnS2 NFs) were solvothermally prepared in the solvent of ethanol, while SnS2 nanoplates (SnS2 NPs) were obtained through the identical conditions except for the solvent of water. The flowers were assembled with numerous nanosheets with very thin thickness, and the NPs exhibited hexagonal shape. When used as the battery-type electrode material for supercapacitors, the SnS2 NFs delivered a specific capacity of as high as 264.4 C g−1 at 1 A g−1, which was higher than the 201.6 C g−1 of SnS2 NPs. Furthermore, a hybrid supercapacitor (HSC) was assembled with the SnS2 as positive electrode and activated carbon (AC) as negative electrode, respectively. The SnS2 NFs//AC HSC exhibited a high energy density of 28.1 Wh kg−1 at 904.3 W kg−1, which was higher than the 24.2 Wh kg−1 at 844.3 W kg−1 of SnS2 NPs//AC HSC. Especially, when the power density was enhanced to the highest value of 8666.8 W kg−1, the NFs-based device could still hold 20.4 Wh kg−1. In addition, both HSC devices showed an excellent cycling stability after 5000 cycles at 5 A g−1. The present method is simple and can be extended to the preparation of other transition metal sulfides (TMSs)-based electrode materials with brilliant electrochemical performance for supercapacitors.

Sustainable development of manganese sulfoselenide nanoparticles anchored graphene oxide nanocomposite for high-performance supercapacitor and lithium-ion battery applications

Transition metal chalcogenides have been described as promising electrode materials for supercapacitors due to their low electronegativity, suitable electrical conductivity, comparatively higher specific capacitance, and favorable electrochemical redox regions. However, the poor electrical conductivity and substantial volume fluctuations provide a significant obstacle to industrial use. A new method to develop metal incorporated GO at the time of GO synthesis and subsequent conversion to metal sulfoselenides is proposed and demonstrated here. This novel process incorporates the advantages of both GO and the metal sulfoselenides for electrochemical energy storage applications. The average size of the nanoclusters was 52 nm as identified by Transmission electron microscopy. As pseudocapacitive electrode GO-MnSSe delivered a specific capacitance of 603 F/g at 0.1 A/g in 1 M KCl of aqueous electrolyte, because of their distinct and stable form. The fabricated 2-electrode device showed a specific capacitance of 98.5 mF/cm2 at 80 µA/cm2, showing good retention of 67 % at the end of the 9000 cycles. As Li-ion battery half-cells, at specific currents of 50, 100, 250, and 500 mA/g, GO-MnS delivered a capacity of 587, 378, 273, and 211 mA h/g respectively, reflecting a retention rate of 64 %, while the specific current was increased 10 times. The initial capacity of GO-MnS and GO-MnSSe at 100 mA/g was 494 and 495 mAh/g respectively, and for GO-MnS and GO-MnSSe at 250 mA/g the delivered capacity values were 376 and 363 mA h/g respectively. Coulombic efficiency (CE) for GO, GO-SW (single wash), GO-MnS, and GO-MnSSe were 99.52 %, 99.6 %, 98.7 %, and 99 % respectively at the end of the 100 cycles. Moreover, GO-MnS were cycled at a higher rate of 500 mA/g for 500 cycles which showed a decay initially nevertheless it stabilized after few cycles and showed a retention of 88 % at the end of 500 cycles from 20th cycle. The ex-situ morphological analysis of GO-MnS were conducted as well as the kinetic of the electrode were studied by before and after cycling EIS measurement. As part of this, as an anode for lithium-ion batteries, high Li-ion storage capacity and cyclic stability were observed.

Facile synthesis of hierarchical core–shell heterostructured ZnO/SnO2@NiCo2O4 nanorod sheet arrays on carbon cloth for high performance quasi-solid-state asymmetric supercapacitors

We synthesized the hierarchical ZnO/SnO2@NiCo2O4 core–shell nanorod sheet arrays (NRSAs) grown on a flexible conductive carbon cloth (CC) substrate by a hydrothermal method. The amalgamation and formation mechanism were proposed. The as obtained ZnO/SnO2@NiCo2O4 core–shell heterostructures is investigated using X-ray diffraction, X-ray photoelectron spectroscopy, high resolution transmission electron microscopy, field emission scanning electron microscopy, and nitrogen adsorption and desorption isotherm analysis. The SnO2 layer which is conducting between ZnO and NiCo2O4 may effectively boost the electrical conductivity of the electrodes and also defend the ZnO from corrosion in the alkaline solution. Benefitting from the core–shell heterostructure formation, the hybrid ZnO/SnO2@NiCo2O4//CC electrode delivered a high specific capacity of 244.5 mA h/g, enhanced cycling stability with a 94.5% retention in specific capacitance even after 10,000 continuous charge–discharge cycles and good rate capability. To utilize the high specific capacity and ultra-long cycling stability, the PVA-KOH gel electrolyte based solid-state hybrid supercapacitor device was assembled with AC//CC as a negative electrode and ZnO/SnO2@NiCo2O4//CC as a positive electrode. The fabricated HSC device delivered a specific capacitance of 117.5 F/g with high energy density (41.7 Wh/kg) and power density (6400 W/kg) along with the outstanding capacitance retention of 94.6% even after 10,000 continuous charging and discharging cycles. With exceptional electrochemical performance, a facile and cost-effective preparation, such ZnO/SnO2@NiCo2O4//CC core–shell heterostructured electrode show a great potential for high-performance electrochemical supercapacitor applications in future.

Binder-Free Zinc-Iron Oxide as a High-Performance Negative Electrode Material for Pseudocapacitors.

The interaction between cathode and anode materials is critical for developing a high-performance asymmetric supercapacitor (SC). Significant advances have been made for cathode materials, while the anode is comparatively less explored for SC applications. Herein, we proposed a high-performance binder-free anode material composed of two-dimensional ZnFe2O4 nanoflakes supported on carbon cloth (ZFO-NF@CC). The electrochemical performance of ZFO-NF@CC as an anode material for supercapacitor application was examined in a KOH solution via a three-electrode configuration. The ZFO-NF@CC electrode demonstrated a specific capacitance of 509 F g−1 at 1.5 A g−1 and was retained 94.2% after 10,000 GCD cycles. The ZFO-NF@CC electrode showed exceptional charge storage properties by attaining high pseudocapacitive-type storage. Furthermore, an asymmetric SC device was fabricated using ZFO-NF@CC as an anode and activated carbon on CC (AC@CC) as a cathode with a KOH-based aqueous electrolyte (ZFO-NF@CC||AC@CC). The ZFO-NF@CC||AC@CC yielded a high specific capacitance of 122.2 F g−1 at a current density of 2 A g−1, a high energy density of 55.044 Wh kg−1 at a power density of 1801.44 W kg−1, with a remarkable retention rate of 96.5% even after 4000 cycles was attained. Thus, our results showed that the enhanced electrochemical performance of ZFO-NF@CC used as an anode in high-performance SC applications can open new research directions for replacing carbon-based anode materials.

Fabrication of nitrogen and phosphorus-codoped porous carbon for high volumetric performance supercapacitors

Porous carbon with outstanding volumetric performance is particularly attractive and important for the miniature energy storage device in practical applications. However, the porous carbon is restricted by its large pore volume and poor density, resulting in the undesirable volumetric performance. Herein, we present a facile strategy for the fabrication of nitrogen- and phosphorus-codoped porous carbons (NPPCs) by utilizing the MnO2 as the self-sacrificial template and oxidant agent, which display its excellent volumetric performance as supercapacitor electrode material. The NPPC-700 electrode demonstrates an outstanding volumetric capacitance of 398.11 F cm–3 at 0.5 A g–1, and the symmetrical device delivers a volumetric energy density of 20.48 Wh L–1 at a power density of 511.0 W L–1 in Na2SO4 electrolyte. The theoretical calculation also shows that the N and P atoms codoping in the NPPC-700 could enhance the Na atom adsorption properties. Furthermore, the electronic structure analysis indicates that ionic and partial covalent bonds coexist during the Na atom adsorption on the carbon surface. These results demonstrate that the NPPC-700 has considerable potential for future applications in high-performance supercapacitors.

Morphology control of polyaniline nanostructures on the surface of reduced graphene oxide/cotton fabric composite electrode for high-performance wearable supercapacitor application

Morphology control of polyaniline nanostructures on the surface of reduced graphene oxide/cotton fabric composite electrode for high-performance wearable supercapacitor application

ZnCo2O4/CNT composite for efficient supercapacitor electrodes

Due to their combination of enhanced electrical conductivity and high-performance electron and ion transport channels, binary metal oxides with well-morphological optimized electrode materials have been attracted the greatest research attention for high-performance supercapacitor applications. An easy co-precipitation method is used to synthesize ZnCo 2 O 4 nanoparticles using NaOH and Urea as precipitation agents. To facilitate electrical conductivity, suitable carbon material such as carbon nanotube (CNT) has been added to make a composite material. The three-electrode system was preferred for estimating specific capacitance of prepared material and optimally efficient ZnCo 2 O 4 /CNT electrode delivered a moderate 888 F/g capacitance at 1 A/g in 3 M KOH and after 5000 charge discharge cycles 94.72% of cycling stability retained at 5 A/g. This paper presents a little price and simple procedure for preparation of ZnCo 2 O 4 /CNT electrode that promotes creative sprit for energy storage applications.

Pseudocapacitive performance of a ternary composite of ferrocene-functionalized graphene nanoribbon, dicationic ionic liquid, and poly (o-aminophenol) for supercapacitor application

The hybridization of dissimilar materials is assumed as a promising route to improve their desired properties for various purposes. In this work, the ferrocene-functionalized graphene nanoribbon/dicationic ionic liquid/poly (ortho-aminophenol) nanocomposite (abbreviated here to GNR-Fc/DCIL/PoAP-NC) was synthesized as a novel active material for high-performance battery-type supercapacitor (SC) applications. In this context, the electrochemical measurement outcomes revealed the significantly enhanced capacitance of the final NC, as compared to those of each component. Additionally, the specific capacitance achieved for the given NC was 395 mAh/g (current density: 1 A/g), wherein energy density (Esg) and power density (Psg) were equal to 29.625 Wh/kg and 852 W/kg, respectively. These results could be attributed to the synergistic effects of the NC components, reducing the charge transfer resistance (Rct) and expanding the charge transfer properties of the GNR. The impact of the molecular weight of the polymeric ionic liquid (PIL) on the electric charge transfer was correspondingly evaluated. Even with the higher number of the charge transfer sites; the charge transfer became more complex following the increase in the chain length, which could be caused by the time-consuming diffusion of the charged species. As a final point, the performance of the novel active material, the GNR-Fc/DCIL/PoAP-NC, in the structure of the two-electrode cell was investigated.

Controllable synthesis of sphere-shaped interconnected interlinked binder-free nickel sulfide@nickel foam for high-performance supercapacitor applications

The fabrication of energy storage electrode materials with high specific capacitance and rapid charge–discharge capability has become an essential and major issue of concern in recent years. In the present work, sphere-shaped interconnected interlinked binder-free nickel sulfide (NiS) grown on the surface of a three-dimensional nickel foam (3DNF) was fabricated by a one-step solvothermal method under optimized synthesis conditions, including different solvents, amounts of sulfur, and experimental reaction times. The fabricated binder-free SS-NiS@3DNF-E electrodes were characterized by a range of spectroscopic and microscopic techniques and further evaluated for their comparative electrochemical supercapacitive performance in half-cell assembly cells. The optimized sphere-shaped interconnected interlinked binder-free SS-NiS@3DNF-E-3 electrode showed an outstanding specific capacitance of 694.0 F/g compared to SS-NiS@3DNF-E-1 (188.0 F/g), SS-NiS@3DNF-E-2 (470.0 F/g), and SS-NiS@3DNF-E-4 (230.0 F/g) as well as excellent cycling stability up to 88% after 6700 continuous charge–discharge cycles, with an energy density of 24.9 Wh/kg at a power density of 250.93 W/kg. The obtained results demonstrate that the interconnected interlinked binder-free NiS@nickel electrode is a potential candidate for energy storage applications.

Nanopetals shaped CuNi alloy with defects abundant active surface for efficient electrocatalytic oxygen evolution reaction and high performance supercapacitor applications

The development of durable, earth abundant and efficient materials tuned for multifunctional applications is need of the time. The assembly of low density, porous, versatile, robust and submissive copper nickel hybrid nanostructure fabricated via reduction method for oxygen evolution reaction (OER) and high performance supercapacitor applications is presented. Copper and nickel-based alloy coated on fluorinated tin oxide (FTO) with composition CuNi/FTO employed for electrochemical test recorded reduced overpotential of 294 mV to get current density of 10 mA cm−2, high electrochemical surface area (0.087 cm2), low Tafel slope 92 mV dec−1 and high specific capacitance (726 mF g−1) at current density of 6 A g−1. The synthesized nanostructured material maintains promising electrical linkage due to large number of catalytic sites with large surface area (130 cm2 g−1). First principle calculations are also performed to examine effect of Cu and Ni vacancy defects on thermodynamic stability and OER of CuNi alloy. Theoretical calculations showed that CuNi alloy with less Cu content provide easier diffusion path owing to its less defect formation energy. Current study highlights some new opening avenues on rational construction and development of cost effective with rich defects to boost the efficiency of energy devices.

Bi2O3 nanosheet-coated NiCo2O4 nanoneedle arrays for high-performance supercapacitor electrodes

Supercapacitors are a promising option for next-generation clean energy storage devices, although their capacitance must still be improved through an appropriate choice of electrode material. Herein, NiCo2O4 nanoneedles coated with Bi2O3 nanosheets are successfully prepared using a two-step hydrothermal process to produce electrodes that may be used for supercapacitors. The proposed electrodes are analyzed using both a range of experimental measurement techniques and density functional theory simulations. The NiCo2O4 nanoneedles provide an ideal skeleton for improving specific surface area and present electrical active sites for the Faraday reaction, while Bi2O3 nanosheets have a great potential for use in supercapacitor applications. The proposed NiCo2O4@Bi2O3 electrode shows a high capacity of 766 F g−1 at 1 A g−1. In addition, an asymmetric supercapacitor based on a NiCo2O4@Bi2O3 positive electrode and activated carbon was produced, which provided a working voltage of 1.6 V, achieved a high energy density of 24 Wh kg−1 at 800 W kg−1, and demonstrated excellent cycling stability (capacitance retention of 82 % after 10,000 cycles at 10 A g−1). These results demonstrate that the proposed NiCo2O4@Bi2O3 heterostructure exhibits potential for application in high-performance supercapacitors.

In-situ growth of Co-Ni hydroxide nanosheets on 3D carbon fiber network with enhanced capacitive performance

The Co-Ni LDH/carbon fiber was prepared through a simple hydrothermal method using the cotton as the carbon source, and investigated as electrode materials for use in supercapacitors. The morphology and structure of the resulting samples were analyzed by SEM, and XRD techniques, respectively, and characterization results proved Ni-Co hydroxide nanosheets were orderly grown on the carbon fiber surface with 3D network structure. In comparison to Co-Ni hydroxides grown on the nickel foam substrate, the Co-Ni LDH/carbon fiber electrode displayed the superior specific capacitance of 1600 F/g at 0.5 A/g and excellent cycling stability of 87.9% retention at 10 A/g after 2000 cycles in 2.0 M KOH electrolyte. AC impedance results illustrated that the electron transfer resistance of Co-Ni LDH/carbon fiber electrode was significantly lower than that of the Co-Ni LDH/Ni foam electrode, illustrating that the carbon fiber can effectively promote the dispersion of Co-Ni LDH, decrease the electron transfer resistance of the as-prepared electrode materials, and ultimately improve the energy storage properties of Co-Ni LDH/carbon fiber. Moreover, the highly ordered Co-Ni LDH nanosheets advanced the contact between KOH electrolyte and the active materials on the electrode, thereby developing the capacitive performance of Co-Ni LDH/carbon fiber. The above results obviously demonstrate 3D Co-Ni LDH/carbon fiber serves as an encouraging electrode material for the application of high-performance supercapacitor.

B/N/O/Zn doped porous carbon materials for supercapacitor with high performance

• B/N/O doped porous carbon materials were prepared by organic ligand to ensure the sustainable acquisition of raw materials and avoid uneven doping. • Synergic effects between heteroatoms and appropriate pore structure provide more active sites and wettability, which is conducive to electrolyte penetration and electron transport. • A high capacitance and high specific energy were obtained. • B, O and N co-doping offers pseudocapacitance for enhancing the capacitive properties. Owing to the need for new-generation energy storage equipment and industrial application, the development of carbon electrode materials with comprehensive electrochemical performances and convenient production processes has become a top priority. In this study, B/N/O/Zn doped carbon materials were prepared using a simple one-step method with 4-(2,4,6-tricarboxylphenyl)-2,2′:6′,2′’-terpyridine (TT) as a raw material. Owing to the doping of many heteroatoms, particularly boron atoms, the optimized TT(Zn/B)-700 exhibits a large specific surface area, proper pore distribution from micropore to macropore, and high degree of graphitization. These structural and morphological features ensure high capacitance performance, such as a specific capacitance of 418.75F/g at 0.5 A/g, and a specific energy of 83.75 Wh/kg at 300 W/kg. In addition, the assembled symmetric supercapacitor exhibits excellent specific energy (5.88 Wh/kg at 150 W/kg, and 5.00 Wh/kg at 3000 W/kg) and specific capacitance (117.5 F/g at 0.5 A/g, and 100.0 F/g at 10 A/g). These carbon electrode materials demonstrate great potential for applications in high-performance supercapacitors.

CuS/polyaniline nanoarray electrodes for application in high-performance flexible supercapacitors

It is imperative to design and fabricate a high-performance free-standing electrode to meet the demand for flexible energy-storage devices with the development of wearable and portable electronics. CuS is an impressive candidate as an ideal pseudo-capacitance material due to its high theoretical capacity, easy preparation and wide source of raw materials. However, the low conductivity of CuS limits its application. Herein, polyaniline (PANI) was coated on CuS @ functional carbon cloth (fCC) to address the inherent defects of CuS using a facile polymerization procedure. Nano-scale PANI arrays with excellent conductivity grown on super-hydrophilic fCC provide a superior electroactive surface and facilitate electron transfer and electrolyte diffusion, which enhance the electrochemical performance of free-standing electrode. The as-prepared PANI/CuS@fCC electrode exhibits outstanding areal capacitance of 2167.2 mF cm−2 at 0.5 mA cm−2, impressive capacitance retention rate (89.2 %) after 5000 cycles at 5 mA cm−2, and satisfactory mechanical properties and flexibility. The assembled symmetrical supercapacitor also exhibits significant rate capacity with a specific capacitance of 816.4 mF cm−2, a high energy density of 0.268 mW h cm−2 at 0.5 mW cm−2and stable cycle performance with a capacitance retention rate exceeding 98 %. This study provides an effective strategy to fabricate advanced and flexible supercapacitor electrode.

A novel hierarchical heterostructure derived from alpha iron oxide supported carbon nano-network for high-performance supercapacitor application

Ferric oxide (Fe2O3) has gained immense attention as a favorable negatrode (negative electrode) material for high-performance supercapacitors for its low cost, high theoretical specific capacity, and abundance in nature. However, owing to its relatively large volume change during the long charge-discharge cycle and comparatively, low conductivity utterly hinders its electrochemical performance. Herein, a composite negative electrode consisting of Fe2O3 nanoparticles (NPs) decorated on CNT-graphene conductive networks (Fe2O3@GR-CNTs/NF) fabricated using a two-step approach is reported. The fabricated composite electrode exhibited a superior specific capacitance (114.2F/g) and good stability (64.2% after 2000 cycles) because of the unique structure of the composite material.

Fabrication of high mechanical stability electrodes and bio-electrolytes for high-performance supercapacitor application

Supercapacitors are promising energy storage systems as they offer high cycle stability and high-power density. However, mechanical, and electrochemical stability of the materials especially at high energy rates are the keys to be addressed. In this study, nanocomposites of molybdenum trioxide MoO3 (Mo) and graphene nanosheets (G) besides with carbon nanotube (CNT) were reported as mechanically stable new electrodes for practical use in devices. A low cost, non-aqueous bio-based gel electrolyte (Glycerol, (Gly)/KOH) was used to highlight the electrochemical stability as well as safety. Supercapacitors containing G-Mo20 and CNT-Mo20 electrodes provided an optimum specific capacitance of 474 F g−1 and 468 F g−1, respectively which is at least 4.5 times enhancement compared to carbon-based device. Additionally, the G-Mo20 and CNT-Mo20 devices provided specific energy of 46 Wh kg-1 and 37 Wh kg-1 at a specific power of 280 W kg-1 and 270 W kg−1, respectively. The supercapacitor with G-Mo20 and CNT-Mo20 successfully completed 17,500 charge-discharge cycles, with a capacitance retention efficiency corresponding to 93% and 88% after 30 days. Furthermore, the supercapacitor (diameter of 1.8 cm2) with the electrode G-Mo20 was successfully operated the LED light. A facile fabrication method, flexibility, robustness and safety are the advantages for the devices that can be suggested for wearable electronics.