Binder-free Supercapacitor Electrode Research Articles

Multifunctional, Novel Zinc-Pyrrole Polymeric MOF as Free Standing, Binder Free Supercapacitor Electrode and Photocatalyst for Organic Pollutant Degradation

Multifunctional, Novel Zinc-Pyrrole Polymeric MOF as Free Standing, Binder Free Supercapacitor Electrode and Photocatalyst for Organic Pollutant Degradation

Flexible All-Carbon Nanoarchitecture Built from In Situ Formation of Nanoporous Graphene Within "Skeletal-Capillary" Carbon Nanotube Networks for Supercapacitors.

It is difficult for carbonaceous materials to combine a large specific surface area with flexibility. Here, a flexible all-carbon nanoarchitecture based on the in situ growth of nanoporous graphene within "skeletal-capillary" carbon nanotube (CNT) networks has been achieved by a chemical vapor deposition (CVD) process. Multi-path long-range conductivity is established, and the porous graphene provides a large specific surface area for charge storage. The flexibility of the films allows them to be directly used as binder-free electrodes for supercapacitors. Since the polymeric binders are saved, the supercapacitors exhibit a higher overall storage density.

Construction of hierarchical and core-shell structured Co3O4@MnO2@NiO nanoarrays as binder-free electrodes for high-performance asymmetric supercapacitors

Remarkable specific capacity and excellent cycle stability of the electrode materials are vital prerequisites for their practical applications. Transition metal oxide-based materials have been extensively explored and employed as electrode materials for asymmetric supercapacitors. However, the actual specific capacitances of these materials are still far lower than their theoretically predicted values. Thus, it is essential to design transition metal oxide with novel structures in order to maximize their specific capacity and cycle stability. Herein, we constructs hierarchical and core-shell structured Co3O4@MnO2@NiO arrays on nickel foam (Co3O4@MnO2@NiO/NF) through a three-step hydrothermal-annealing process, and use them as a direct binder-free electrode for pseudocapacitors. The as-prepared layered hierarchical Co3O4@MnO2@NiO/NF electrode exhibits an impressive specific capacitance of 6.42 F cm−2 (2054 F g−1) at 1 mA cm−2 in a three-electrode configuration, which is largely because of the synergistic effect among Co3O4, MnO2 and NiO. Furthermore, the 3D nanoarray structure can provides a larger specific surface area, a rapid diffusion path, and more active sites that allow to achieve improved electrochemical performance. In addition, the assembled Co3O4@MnO2@NiO/NF//AC/NF ASC all-solid-state asymmetric supercapacitor (ASC) displays a remarkable energy density (30.7 Wh kg−1 at 400.4 W kg−1), demonstrating that this all-solid-state ASC owns considerable potential for practical applications in such high-performance energy storage devices.

Ballistic-aggregated Carbon Nanofoam in Target-side of Pulsed Laser Deposition for Energy Storage Applications.

In pulsed laser deposition, along the traditionally exploited deposition on the front-side of the plasma-plume, a coating forms on the surface of the target as well. For reproducibility, this residue is usually cleaned and discarded. Here we instead investigate the target-side coated materials and employ them as a binder-free supercapacitor electrode. The ballistic-aggregated, target-side nanofoam is compact and features a larger fraction of sp2-carbon, higher nitrogen content with higher graphitic-N and lower oxygen content with fewer COOH groups than that of diffusive-aggregated conventional nanofoams. They are highly hydrogenated graphite-like amorphous carbon and superhydrophilic. The resulting symmetric micro-supercapacitor delivers higher volumetric capacitance of 522 mF/cm3 at 100 mV/s and 104% retention after 10000 charge-discharge cycles over conventional nanofoam (215 mF/cm3 and 85% retention) with an areal capacitance of 134 μF/cm2 at 120 Hz and ultrafast frequency response. Utilizing the normally discarded target-side material can therefore enable high performing devices while reducing waste, cost and energy input per usable product. leading towards a greater sustainability on nanomaterials synthesis and deposition techniques.

The phosphorous-doped 2D nanosheet assembled 3D Mn2V2O7 microflowers on Ni foam as a binder-free electrode for high energy density asymmetric supercapacitor application

In recent times, transition-metal oxides have been recognized as highly promising candidates for supercapacitor applications. Nevertheless, their progress in diverse fields has been hindered by challenges such as poor electrical conductivity and a shortage of active reaction centers. Doping heteroatoms would overcome these drawbacks and enhance the supercapacitor properties in transition metal oxides. Herein, the phosphorous-doped 2D nanosheet assembled 3D Mn2V2O7 micro flowers were grown on the Nickel foam using the hydrothermal method and successively phosphatized in a tube furnace, which was utilized as a binder-free supercapacitor electrode. The synthesis process involved varying the concentration of phosphorus (P), resulting in the successful formation of uniform P-decorated Mn2V2O7 microflowers. The unique microflower structure and doping P into the Mn2V2O7 material enhance the electrochemical properties with a specific capacity of 850C g−1 (1545 F g−1) at 1 A g−1 in a three-electrode cell. Moreover, the assembled Mn2V2O7–600/NF//AC device delivers a specific capacity of 258C g−1 (211 F g−1) at 1 A g−1 with a remarkable rate of 47 % at a high current density of 20 Ag −1. The device achieved a maximum energy density of 43.2 Wh kg−1 at a power density of 604.7 W kg−1, and it maintained 91 % of initial capacity after 10,000 charge/discharge cycles at 20 A g−1. These results suggest that the P-doping 2D nanosheet assembled 3D Mn2V2O7 could be promising electrode materials for supercapacitor applications.

A High-Performance, Low Defected, and Binder-Free Graphene-Based Supercapacitor Obtained via Synergistic Electrochemical Exfoliation and Electrophoretic Deposition Process.

An integrated electrochemical exfoliation and electrophoretic deposition (EPD) method is developed to achieve a high-performance graphene supercapacitor. The electrochemical delamination of graphite sheet has obtained a low-defected few-layer graphene adorned with oxygen-containing functional groups. Then, the EPD process produced a binder-free electrode to alleviate the graphene restacking problem. The electrode prepared using a deposition voltage of 5 V exhibits the highest specific capacitance of 145.95 F/g at 0.5 A/g from three-electrode measurement. Moreover, this EPD-prepared electrode also demonstrates superior electrochemical properties compared to electrodes fabricated using PVDF binder. In the real symmetrical cell, the EPD-prepared electrode also shows excellent performance with a high rate capability of 82.31 % (from 0.5 A/g to 10 A/g), high cycling stability of 95.00 % (at 5 A/g) after 10,000 cycles, and rapid frequency response with short relaxation time ( ) of 9.73 ms. These results indicate that this integration method is beneficial to construct a high performance binder-free supercapacitor electrode consisting of low-defected graphene materials, low electrode resistance, and less agglomeration of graphene sheets by utilizing an environmentally friendly process.

One-pot synthesis of tungsten oxynitride/nitrogen-doped graphene with particle-sheet hybrid nanostructure as a highly effective binder-free supercapacitor electrode

High-performance nanoscale composites have achieved predominance as promising materials for supercapacitor applications. Graphene nanosheets decorated with transition metal oxynitride nanoparticles can be highly beneficial in improving supercapacitor properties. However, they are hardly retrieved, and their electrochemical characterizations and inherent charge-storage mechanisms have not been deeply investigated. Herein, tungsten oxynitride decorated nitrogen-doped graphene (WON-NG) is synthesized by a facile one-pot strategy in a particle-sheet hybrid nanostructure. The nanocomposite is grown directly on a nickel foam (NF) as the current collector through the synthesis process. X-ray photoelectron spectroscopy and TEM images have confirmed the particle-sheet hybrid nanostructure of the prepared nanocomposite with tungsten oxynitride nanoparticles and nitrogen-doped graphene nanosheet. The oxygen and nitrogen-based redox groups, which synergistically coexist in the hybrid network, inherently cooperate in the electrochemical activities of the nanocomposite. The electrochemical measurements show that the WON-NG|NF electrode can deliver a superior specific capacitance of 1079.4 F g−1 (4.6 F cm−2) at 1 A g−1 in 1 M KOH aqueous electrolyte. In-depth investigations suggest that the diffusive-controlled process governs the charge storage mechanism at all scan rates in the composite for the advantageous porous morphology. The assembled all-solid-state asymmetric supercapacitor device exhibits a high energy density of 81.6 Wh kg−1 and a power density of 5005.4 W kg−1. Also, the designed devise shows an excellent cycle life with 87.7% capacitance retention of 10,000 cycles.

Novel Design and Synthesis of Ni-Mo-Co Ternary Hydroxides Nanoflakes for Advanced Energy Storage Device Applications

Three-dimensional interconnected mesoporous nanoflakes of amorphous Ni-Mo-Co trimetallic hydroxides were successfully deposited on a Ni foam (NF) using a facile, environmentally friendly, and scalable electrochemical deposition method. The elemental composition of the nanoflakes, including Ni2+, Mo6+, and Co2+, was characterized by X-ray photoelectron spectroscopy (XPS), while the morphology and particle size of the synthesized nanomaterials were examined using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The Ni-Mo-Co trimetallic hydroxides on NF were employed as binder-free electrodes for supercapacitors. The Ni-Mo-Co trimetallic hydroxides with a Ni/Mo/Co ratio of 1/1/0.4 exhibited outstanding long-term cyclability over 5000 cycles, with a high reversible specific capacitance of 2700 F g−1 and a high capacitance retention of 96.63% at 10 A g−1. Furthermore, they demonstrated excellent rate performance, maintaining a capacitance of 2429 F g−1 at a current of 50 A g−1, which corresponds to approximately 80% capacitance retention compared to the capacitance at 2 A g−1. The superior performance of these Ni-Mo-Co trimetallic hydroxides can be attributed to their mesoporous hierarchical architecture, which provides large open spaces between the interconnected nanoflakes, numerous electroactive surface sites, facile electron transmission paths, and the synergistic effects of the trimetallic components. These findings demonstrate that Ni-Mo-Co trimetallic hydroxides are promising electrode materials, offering both high capacitance and long-term cyclability for supercapacitors.

Electrosynthesis of Co-ZIF Using Bio-Derived Solvents: Electrochemical Evaluation of Synthesised MOFs as a Binder-Free Supercapacitor Electrode in Alkaline Electrolyte

Electrosynthesis of Co-ZIF Using Bio-Derived Solvents: Electrochemical Evaluation of Synthesised MOFs as a Binder-Free Supercapacitor Electrode in Alkaline Electrolyte

Hierarchically decorated ZnO/CoOx nanoparticles on carbon fabric for high energy–density and flexible supercapacitors

Exploring the electrochemical performance of metal/metal oxide nanoparticle composites is vital for enhancing the charge storage capability of supercapacitors. Herein, electrodes coated with ZnO/CoOx are fabricated by soaking cotton fabric seeded with 2-methylimidiazole in an ethylene glycol–based solution containing Zn and Co salts. The use of cotton fabric can reduce textile industrial waste while achieving high capacitance and sustainable energy for wearable electronics. In addition, the three-dimensional network of conductive flexible carbon derived from cotton fabric facilitates rapid ion transport kinetics at interlayers. The concentrations of Zn and Co salts are varied to produce ZnO/CoOx samples and determine the optimal salt ratio for superior electrochemical performance. The optimal sample exhibits a capacitance of 1.95 F cm−2 at 5 mA cm−2 and an energy density of 725 μWh·cm−2 over a wide potential window of 1.6 V. The long-term stability test results of the symmetric cells indicate 94 % capacitance retention after 12,000 charge–discharge cycles, emphasizing the advantages of mixed metallic oxides with cellulose-derived carbon fabric for supercapacitor electrodes. This study offers valuable insights into the fabrication of high-performance, flexible, and binder-free supercapacitor electrodes as a scalable alternative for practical applications.

Chemical vapor deposition-grown single-layer graphene-supported nanostructured Co3O4 composite as binder-free electrode for asymmetric supercapacitor and electrochemical detection of caffeic acid

In this study, we developed a monolayer graphene/nanostructured cobalt oxide (MLG/Co3O4) composite for asymmetric supercapacitor and electrochemical sensor applications. The MLG was grown by chemical vapor deposition process and the Co3O4 nanostructures were electrodeposited on the MLG surface. Scanning electron microscopy proved that there were flower-like nanostructured Co3O4 densely electrodeposited on the MLG surface. At a current density of 3 mA cm−2, the MLG/Co3O4 composite produced an areal capacitance of 3.73 F cm−2. After 10,000 cycles, the composite electrode still had 93.6 % of its initial capacitance at 5 mA cm−2. The asymmetric system displayed an areal capacitance of 929 mF cm−2 at 4 mA cm−2 with good cycle stability. The asymmetric electrode produced a specific energy of 51 μWh cm−2 and a specific power of 11.1 mW cm−2. Cyclic voltammetric measurements demonstrated that the composite showed redox peaks at 0.48 eV and 0.09 eV toward the determination of CA. With a sensitivity of 0.13 µA/µM/cm2 and a limit of detection of 0.009 µM, the composite showed CA concentrations, ranging from 0.5 to 480 M. The composite displayed excellent selectivity and the current produced for the interfering compounds was exceedingly low. Using the composite electrode, the spiked CA in red wine and green tea samples recovered remarkably effectively.

Growth of CQD/PPy on cotton cloth as a binder-free high-performance flexible electrode for symmetric supercapacitor

Benefited from the continuous development of nanomaterials, wearable microelectronics with flexible and miniaturized features are booming, and smart textiles are attracting more attentions because of their superior flexibility and perfect safety. The combination of conductive polymers and flexible substrates has created a new field for flexible supercapacitors. Herein, cotton cloth (CC), which is commonly used in daily life, was selected as the flexible substrate and a layer of CQDs was uniformly grown on the CC fibers, and then pyrrole was directly grown on CC by in-situ polymerization under Fe3+ initiation to realize the tight bonding between the conductive polymer and the flexible substrate. The electrochemical properties of the composite electrode could be controlled by changing the amount of CQD. The obtained CC@CQD@PPy electrode has a high specific capacitance (C) of 537.9 F/g at 0.5 A/g. The assembled symmetric CC@CQD@PPy supercapacitor exhibits an excellent energy density (E) of 18.7 Wh/kg at a power density (P) of 125.0 W/kg, and a supreme cycling stability with a capacitance retention of 77.9 % after 10,000 cycles. In addition, the CC@CQD@PPy supercapacitor has excellent flexibility, with almost unchanged electrochemical performance under different bending angles, and the assembled all-solid-state supercapacitor has good electrochemical properties.

Simple and affordable synthesis of a binder-free nickel-zinc sulfide electrode for high-performance supercapacitors

Due to the increasing demand for renewable energy solutions, aqueous energy systems have emerged as promising and sustainable technologies. Nanostructured transition metal sulfides, renowned for their exceptional properties, are prime candidates for electrochemical supercapacitors. In this study, we present the synthesis of nickel-zinc sulfide (Ni-Zn-S) as a binder-free supercapacitor material using the affordable successive ionic layer adsorption and reaction simple technique. The active nanomaterial was directly deposited onto a 3D Ni foam current collector substrate, negating the need for a binder. The synergistic combination of Ni and Zn enhances the electrode capacitance. Various electrochemical techniques were used to evaluate the loaded active material as a binder-free supercapacitor electrode in a 6 M KOH electrolyte. Results indicate pseudocapacitive performance, achieving a high specific capacitance of 400F/g at 0.7 A/g. This material retains 97 % of its capacity, even after 2000 cycles, showcasing exceptional long-term cycling stability. These findings underscore the potential of the Ni-Zn-S electrode for delivering low-cost, high-performance supercapacitors.

PPy-PdO modified MXene for flexible binder-free electrodes for asymmetric supercapacitors: Insights from experimental and DFT investigations

Binder-free, flexible electrodes of V2C MXene, V2C-PPy, and V2C-PPy-PdO (a ternary composite of vanadium carbide, polypyrrole, and palladium oxide) were fabricated using a simplified, one-step electrodeposition method. A comprehensive assessment has subsequently been conducted on the microstructural and electrochemical attributes of these electrode materials when utilized in supercapacitors with a 1 M H2SO4 electrolyte. Notably, an impressive specific capacitance of 487F g−1 is achieved for V2C-PPy-PdO ternary composite at 1 A/g. This exceptional performance is due to the considerable active surface area and inherent structural stability of the host material. These factors significantly enhanced the electrochemical reaction kinetics and cyclic reversibility. Furthermore, the V2C-PPy-PdO composite demonstrated a notable specific capacitance of 250F g−1 when integrated into an asymmetric coin cell configuration alongside activated porous carbon under a current density of 1 A/g. Remarkably, it maintained an outstanding capacitance retention of 92 % across 10,000 charge–discharge cycles. Our experimental discoveries were additionally substantiated through the Density Functional Theory calculations, which unveiled that the inclusion of PdO within the V2C-PPy-PdO composite led to an augmentation of electronic states near the Fermi level. This increase in electronic states ultimately improved the quantum capacitance, rendering the V2C-PPy-PdO composite a highly promising candidate for supercapacitor applications.

Bimetallic NiCo2Se4/Fe2CoSe4 chrysanthemum flowers assembled by nanosheets: An efficient electrode material for hybrid supercapacitor applications

Transition metal selenides have excellent promise for high-performance electrode materials owing to their great electrical conductivity and theoretical capacity. Unfortunately, the electrochemical performance of single-metal selenides is undesirable because of their low energy density and poor cyclic stability, and one practical approach is to introduce heteroatoms to create bimetallic selenides. Herein, a novel bimetallic NiCo2Se4/Fe2CoSe4 chrysanthemum flower assembled by nanosheets on NiF was synthesized via a hydrothermal process as a binder-free electrode for a hybrid supercapacitor. Because of the presence of plentiful redox active sites, unique architecture with large surface area and mesoporous channels, desirable electrical conductivity, and synergistic effect of Ni, Co, and Fe, the bimetallic NiCo2Se4/Fe2CoSe4 electrode material shows significantly increased electrochemical performance. Interestingly, the bimetallic NiCo2Se4/Fe2CoSe4 electrode material shows an outstanding specific capacity of 323.66 mAhg−1 (1175.97 Cg−1) at 1 Ag−1, retaining 91.08% of the initial capacity at 20 Ag−1, with long-lasting cyclic stability of 91.08% after 10,000 GCD cycles at 20 Ag−1. A binder-free bimetallic NiCo2Se4/Fe2CoSe4 @NiF electrode's outstanding electrochemical efficiency can be related to the existence of two bimetallic selenides, and beneficial interaction, which yields quick charge transfer reactions. Moreover, the NiCo2Se4/Fe2CoSe4@NiF//AC@NiF hybrid supercapacitor by bimetallic NiCo2Se4/Fe2CoSe4@NiF (positive electrode) and activated carbon (AC@NiF, negative electrode) displayed specific energy which is 51.83 Whkg−1 at 749.83 Wkg−1 and 34.2 Whkg−1 at 14996.34 Wkg−1 at 20 Ag−1 and superior stability of 92.33% after 10,000 GCD cycles. This research provides some insight into the design of an electrode material with a flower-like decorated with nanosheets morphology for hybrid supercapacitors.

Revolutionizing energy storage with advanced reduced graphene oxide-wrapped MnSe@CoSe@FeSe2 nanowires.

Thanks to their good redox activity properties and exceptional conductivity, metal selenides (MSs) have attracted great attention as prospective positive electrodes for hybrid supercapacitors. However, they demonstrate low-rate capacities and poor endurance. Nanomaterials fabricated from MSs and reduced graphene oxide (rGO) with a porous skeleton can effectively mitigate the above-mentioned problems. Herein, porous MnSe@CoSe@FeSe2 nanowires wrapped with rGO on nickel foam (NF@MCFS-rGO) are manufactured as a binder-free electrode for a hybrid supercapacitor. The obtained NF@MCFS-rGO, acting as a positive electrode, has distinct advantages such as (1) the porous nanowires are helpful for fast electrolyte penetration, (2) the conductivity of the MCFS is further improved when combined with rGO, and (3) wrapping MCFS within the rGO endows the nanomaterial with much better structural durability. Capitalizing on the high conductivity of the rGO and the porous morphology, the fabricated NF@MCFS-rGO manifests impressive characteristics with a capacitance of 1830 F g-1 at 1 A g-1 and only 6.75% capacitance loss within 10 000 cycles. By matching NF@MCFS-rGO with activated carbon (AC), the fabricated apparatus (AC\\NF@MCFS-rGO) reveals an energy density (ED) of 64.6 W h kg-1 and a long lastingness of 90.55% after 10 000 cycles.

Unification of DAQ-rGO-PEDOT as binder-free ternary nanocomposite electrode for high performance solid-state symmetrical supercapacitor

A high energy density hybrid supercapacitor has been developed from highly π-conjugated 1,4-diaminioanthraquinone covalently bonded to reduced graphene oxide (DAQ:rGO). The drop casting of DAQ:rGO suspension onto nanostructured PEDOT matrixes has enhanced the microstructure/orderliness, higher homogeneity as confirmed by Raman, FE-SEM and HRTEM studies. The high gravimetric capacitance (622.4 F g−1 at 1 A g−1) emerges from extensively porous matrix of nanostructured PEDOT and low band gap of DAQ:rGO evident from a voltage window of -0.2 to 0.8 V facilitating the redox activity of DAQ. In addition, solid-state symmetric supercapacitor based on ternary electrode with free standing PVA-H2SO4 gel electrolyte possesses specific capacitance of 492.5 F g−1 at 1.5 A g−1 with exceptional energy density (68.39 W h kg−1) and excellent cyclic stability (retaining 100% capacitance after 10,000 cycles. The ability of the four devices to illuminate the LED for 120 s manifests utility of the nanocomposite for future microelectronics.

Exploring the potential of simultaneous nanoarchitectonics and utilization of Co-MOFs electrode as well as powder for aqueous supercapacitors

The current study emphasized a leaf-like architecture of Co-MOFs electrodes on a stainless-steel mesh substrate (Co-MOFs/SSM) and Co-MOFs powder for supercapacitors (SCs), with a particular emphasis on utilizing the residual product as an electrode material instead of discarding it. Additionally, the investigation explored the impact of using a binder and binder-free electrode for SCs. The Co-MOFs powder (R-Co-MOFs) was obtained from the residual material left after synthesizing Co-MOFs/SSM using the reaction-diffusion framework method. The structural and compositional analysis confirmed the formation of both Co-MOFs/SSM and R-Co-MOFs. The morphological studies revealed an interconnected and non-interconnected leaf-like architecture for Co-MOFs/SSM and R-Co-MOFs respectively. R-Co-MOFs were screen printed on a stainless-steel mesh substrate (R-Co-MOFs/SSM) and used as an electrode material for SCs. The Co-MOFs/SSM and R-Co-MOFs/SSM exhibited maximum specific capacitance (Cs) of 534 and 269 F/g at 5 mV/s respectively. Moreover, Co-MOFs/SSM and R-Co-MOFs/SSM exhibited retention rates of 62 % and 99 % after 5000th cycles, respectively. Likewise, the symmetric aqueous device, Co-MOFs/FSS//Co-MOFs/FSS achieved a maximum Cs of 85 F/g at 10 mV/s which surpassed the value of 34 F/g for R-Co-MOFs/SSM//R-Co-MOFs/SSM. It also showed higher energy density and power density values of 19.31 Wh/kg and 1333 W/kg at 4 mA compared to R-Co-MOFs/SSM//R-Co-MOFs/SSM, respectively. The Co-MOFs/SSM//Co-MOFs/SSM and R-Co-MOFs/SSM//R-Co-MOFs/SSM revealed retention rates of 72 % and 98 % after 3000th cycles respectively. This investigation provides valuable insights to researchers regarding the sustainable synthesis and utilization of Co-MOFs electrodes and powder for SCs.

Electrodeposited ultra-thin FeCo2O4 nanosheets on nickel foam as binder-free electrodes for high-performance supercapacitors

The cobalt-based spinel oxides MCo2O4(M = Ni, Mn, Cu, Fe, etc.) have garnered significant attention due to their potential applications in energy storage. In this study, ultra-thin FeCo2O4 nanosheets have been synthesized through a facile electrodeposition method and used as binder-free electrodes for high-performance supercapacitors. The results indicate that the FeCo2O4 nanosheet (FCS) electrode obtained through 5 min of electrodeposition using ferrous salt (FeSO4) as the precursor has a more abundant pore structure and exhibits the best electrochemical performance. The specific capacitance of the FeCo2O4 nanosheets electrode reaches 679 F g−1 at a current density of 1 A g−1, and it retains 92.9 % of its initial capacitance after undergoing 5000 cycles. In addition, the assembled FeCo2O4 nanosheet (FCS)//activated carbon (AC) asymmetric supercapacitor shows a high energy density of 62.5 Wh kg−1 at 750 W kg−1 and with a capacitance retention of 91.3 % after 5000 cycles. Furthermore, the electrodeposition method utilized in the synthesis of the FeCo2O4 nanosheets is cost-effective, environmentally friendly, and can be employed to fabricate other MCo2O4 materials with superior electrochemical properties.

Optimized 3D interconnected foam-like NiO@rGO composite as a binder-free electrode for high-performance asymmetric supercapacitor

Bonding of transition metal oxides and highly conductive carbon materials to exploit the synergistic effect of both materials has been proven to be an efficient means to develop high-capacity electrode materials. A unique interconnected foam-like NiO@rGO structure was constructed by loading the NiO nanoparticles onto rGO frameworks as a binder-free supercapacitor electrode via three steps including hydrothermal reaction, electrodeposition and heating treatment. The morphology and crystallinity were tuned by controlling the electrodeposition time and heating temperature, and the electrochemical properties of the NiO@rGO composites were systematically investigated. The optimized NiO@rGO-250 composite showed excellent electrochemical properties (1399 F g−1 at 1 A g−1) and superior cycling stability. Furthermore, an asymmetric supercapacitor using NiO@rGO and active carbon as two electrodes achieved a high specific energy of 40.4 Wh k g−1 at a specific power of 750 W k g−1.