Binder-free Electrode For High-performance Supercapacitors Research Articles

Hierarchically structured Cu2P2O7 nanoflakes as a binder-free electrodes for high-performance supercapacitors

Metal phosphates-derived materials are emerging as promising candidates for electrode materials in energy storage systems due to their excellent redox properties and high electrical conductivity. In this work, we present a novel study and first report on the fabrication of binder-free electrodes using ultrathin Cu2P2O7 nanoflakes, facilitated through a cost-effective and industrially scalable chemical bath deposition (CBD) technique. These electrodes exhibit a unique surface architecture resembling micro-spherical flower structures, which are directly grown on flexible and conductive nickel foam (NF) substrates. The nanoscale structure of the Cu2P2O7 electrodes is meticulously designed to provide high porosity and an impressive specific surface area, allowing for efficient electrolyte ion infiltration. Consequently, these electrodes exhibit an exceptional specific/areal capacitance value of 1187 F g−1, 1894 mF cm−2 at a scan rate of 5 mA cm−2 and a specific capacity value of 644 C g−1. Notably, when integrated into an aqueous asymmetric supercapacitor (AASC) device, the Cu2P2O7-derived micro-sized flower structure delivers a significant energy density of 39.46 Wh kg−1, a notable specific power of 1.08 kW kg−1, and maintains an exceptional 99 % retention even after 10,000 charge/discharge cycles. This research highlights the potential of transition metal phosphates (TMPOs), specifically Cu2P2O7, as superior electrode materials for supercapacitor applications, offering a scalable and cost-effective approach for enhancing energy storage performance.

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.

Construction of 3D interconnected NiCo2S4/bio-carbon coated Ni foam as binder-free electrode for high-performance supercapacitor

Although transition metal hydroxides/sulfides are considered as promising potential electrode materials for supercapacitors due to their excellent electrochemical activity, the low electrical conductivity, easy agglomeration of nanomaterials and poor rate performance seriously hinder their practical applications. Herein, we construct 3D interconnected binder-free electrode NiCo2S4/bio-carbon coated nickel foam (NiCo2S4/GRCNF) by growing NiCo2S4 nanosheets on the surface of low-cost and highly conductive GRCNF substrate via a simple hydrothermal reaction followed with subsequent sulfidation. As suggested by systematic characterizations, the advantages of obtained NiCo2S4/GRCNF include that the ultrathin 3D interconnected network of NiCo2S4 can furnish massive electrochemically active sites for faradic reaction, and the highly conductive GRCNF substrate promotes electron transfer and meanwhile prevents the aggregation of NiCo2S4 nanosheets. With a high specific capacitance of 7.71 F cm−2 at 3 mA cm−2, NiCo2S4/GRCNF has a huge application advantage over the contrast samples Ni-Co LDH/NF (3.29 F cm−2) and Ni-Co LDH/GRCNF (5.97 F cm−2). In addition, NiCo2S4/GRCNF shows a much higher rate performance (82.1%) than Ni-Co LDH/NF (44.5%) and Ni-Co LDH/GRCNF (66.4%). Furthermore, hybrid supercapacitor NiCo2S4/GRCNF//GNPC which is assembled with NiCo2S4/GRCNF as the anode possesses an impressive energy density of 0.429 mWh cm−2 at a power density of 7.023 mW cm−2 and good cycling stability (82.3% over 5000 cycles). The outstanding electrochemical performance of NiCo2S4/GRCNF suggests that the reported strategy provides new inspiration for the design and preparation of new binder-free composite electrodes for electrochemical energy storage.

Direct Growth of Binder-Free CNTs on a Nickel Foam Substrate for Highly Efficient Symmetric Supercapacitors.

In the modern civilized world, energy scarcity and associated environmental pollution are the center of focus in the search for reliable energy storage and harvesting devices. The need to develop cheaper and more competent binder-free electrodes for high-performance supercapacitors has attracted considerable research attention. In this study, two different procedures are followed to enhance the growth of carbon nanotubes (CNT-E and CNT-NF) directly coated on a Ni-foam substrate by a well-functioning chemical vapor deposition (CVD) method. Thus, directly grown optimized CNT electrodes are used as electrodes for electrochemical devices. Furthermore, solid-state symmetric supercapacitors are fabricated using CNT-NF//CNT-NF, and fruitful results are obtained with maximum specific capacitance (250.51 F/g), energy density (68.19 Wh/kg), and power density (2799.77 W/kg) at 1 A/g current density. The device exhibited good cyclic stability, with 92.42% capacitive retention and 99.68% Coulombic efficiency at 10 000 cycles, indicating the suitability of the electrodes for practical applications. This study emphasizes the importance of studying the direct growth of binder-free CNT electrodes to understand the actual behavior of electrodes and the proper storage mechanism.

In Situ Growth of MnO2 Nanosheets on a Graphite Flake as an Effective Binder-Free Electrode for High-Performance Supercapacitors.

In this work, manganese dioxide (MnO2) nanosheets in situ loaded on a high-purity graphite flake (GF) were prepared by one-step hydrothermal deposition. It was found that the specific capacitance value of a single MnO2/GF electrode was 882 F/g at a current density of 1.0 A/g in a KOH electrolyte, and the specific capacitance retention of the MnO2/GF electrode can reach about 90.1% after 5000 charge-discharge cycles at a current density of 10 A/g. Furthermore, a MnO2/GF∥MnO2/GF symmetric supercapacitor device was fabricated with two pieces of MnO2/GF electrodes and ordinary filter paper with a 1 M KOH/PVA gel electrolyte as a separator. The single symmetric device displayed a high energy density of 64.2 Wh/kg at a power density of 400 W/kg within an applied voltage of 1.6 V, and this value was superior to those of previously reported MnO2-based systems. A tandem device consisting of a five-series tandem device (the applied voltage of a single device was 0.7 V) and a three-series tandem device (the applied voltage of a single device was 1.6 V) was prepared to drive a red light-emitting diode (LED). These findings open up application prospects for MnO2-based composite electrode materials for high-performance supercapacitors.

In–situ synthesis of MnO dispersed carbon nanofibers as binder-free electrodes for high-performance supercapacitors

Manganese oxides have attracted great interest as promising pseudocapacitive materials due to its low cost, variable oxidation states, and high theoretical capacitance. In this work, we report the in-situ synthesis of MnO-dispersed carbon nanofibers (CNFs) using electrospinning and a unique two-step carbonization technique. While the single-step carbonization resulted in mixed MnxOy forms, however, by employing a suitable and optimized two-step carbonization, we were able to obtain CNFs assimilated with MnO nanoparticles (MnO-CNFs). The synthesized MnO-CNF electrodes achieved a high specific capacitance of 246 F g−1 at 0.5 A g−1 in a three-electrode system. A symmetric supercapacitor device assembled with these electrodes exhibited remarkable electrochemical performance with a maximum power density of 5000 W kg−1, maximum energy density of 14 W h kg−1, and an excellent cycling stability (97.5% retention after 10,000 cycles). The exceptional electrochemical performance of MnO-CNFs makes them promising electrode materials for practical energy storage applications.

Facile Synthesis of NiCo2O4 Nanowire Arrays/Few-Layered Ti3C2-MXene Composite as Binder-Free Electrode for High-Performance Supercapacitors.

Herein, a 3D hierarchical structure is constructed by growing NiCo2O4 nanowires on few-layer Ti3C2 nanosheets using Ni foam (NF) as substrate via simple vacuum filtration and solvothermal treatment. Ti3C2 nanosheets are directly anchored on NF surface without binders or surfactants, and NiCo2O4 nanowires composed of about 15 nm nanoparticles uniformly grow on Ti3C2/NF skeleton, which can provide abundant active sites and ion diffusion pathways for enhancing electrochemical performance. Benefiting from the unique structure feature and the synergistic effects of active materials, NiCo2O4/Ti3C2 exhibits a high specific capacitance of 2468 F g−1 at a current density of 0.5 A g−1 and a good rate performance. Based on this, an asymmetric supercapacitor (ASC) based on NiCo2O4/Ti3C2 as positive electrode and activated carbon (AC)/NF as negative electrode is assembled. The ASC achieves a high specific capacitance of 253 F g−1 at 1 A g−1 along with 91.5% retention over 10,000 cycles at 15 A g−1. Furthermore, the ACS presents an outstanding energy density of 90 Wh kg−1 at the power density of 2880 W kg−1. This work provides promising guidance for the fabrication of binder-free, free-standing and hierarchical composites for energy storage application.

Highly conductive, hierarchical porous ultra-fine carbon fibers derived from polyacrylonitrile/polymethylmethacrylate/needle coke as binder-free electrodes for high-performance supercapacitors

Here, the treated ultra-fine needle coke particles (UNCs) are introduced in hierarchical porous ultra-fine carbon fibers by electrospinning and thermally treatment process of two immiscible polymers and UNCs precursor. The structure, morphology and electrochemical performance of the ultra-fine carbon fibers derived from polyacrylonitrile (PAN)/polymethylmethacrylate (PMMA)/UNCs are explored in detail. As a result, when the mass ratio of PAN to PMMA reaches 6: 4, the ultra-fine carbon fibers derived from PAN/PMMA/UNCs display a high surface area of 919.3 m 2 g −1 , a suitable mesoporous structure of meso/micro = 1.59. and exhibit a remarkable specific capacity (387.2 F g −1 at 0.5 A g −1 ) and excellent power performance. Furthermore, a comprehensive electrochemical performance of symmetrical supercapacitors was obtained: prominent energy density (27.87 Wh·kg −1 at 489 W kg −1 ) and ideal cyclic stability (97.5% capacity retention after 10,000 cycles at 1 A g −1 ). In addition, hierarchical porous ultra-fine carbon fibers derived from blend polymer and needle coke with high degree of graphitization, which provide a potential optional application for served as binder-free electrodes for electrochemical energy storage devices. • UNCs with high compatibility in electrospinning precursor were prepared. • The Free-standing carbon fiber electrodes show excellent performance. • The as-assembled supercapacitor exhibits high energy density and remarkable cycle life.

Fabrication of three-dimensional WO3 nanotube bundles on carbon cloth as a binder-free electrode for high-performance supercapacitors

The WO3 nanotube bundles are fabricated on carbon cloth, exhibiting high specific capacitance, low charge transfer resistance, and excellent stability.

Cobalt-Based Metal-Organic Framework Electrodeposited on Nickel Foam as a Binder-Free Electrode for High-Performance Supercapacitors

Cobalt-Based Metal-Organic Framework Electrodeposited on Nickel Foam as a Binder-Free Electrode for High-Performance Supercapacitors

A cobalt-based metal–organic framework electrodeposited on nickel foam as a binder-free electrode for high-performance supercapacitors

Co-MOF/NF has been prepared by cathodic electrodeposition using highly active cobalt as a surface modifier, and shows improved capacitance performances.

Co-electrophoretic deposition of Mn2O3/activated carbon on CuO nanowire array growth on copper foam as a binder-free electrode for high-performance supercapacitors

Co-electrophoretic deposition of Mn2O3/activated carbon on CuO nanowire array growth on copper foam as a binder-free electrode for high-performance supercapacitors

FeCo2S4/NH2-GQDs nanoflowers supported on Ni foam as novel binder-free electrode for high-performance supercapacitors

FeCo2S4/NH2-GQDs nanoflowers supported on Ni foam as novel binder-free electrode for high-performance supercapacitors

Construction of MnO2 nanosheets@graphenated carbon nanotube networks core-shell heterostructure on 316L stainless steel as binder-free supercapacitor electrodes

Carbon nanotubes are regarded as typical and promising electrode materials in supercapacitors. However, small specific capacitance of carbon nanotubes restricts the practical application in high energy density devices. Herein, MnO2 nanosheets@graphenated carbon nanotube networks are synthesized directly on 316L stainless steel as binder-free electrodes for high-performance supercapacitors. Graphenated carbon nanotube networks are grown in-situ on stainless steel by chemical vapor deposition method followed by annealing treatment. Subsequently, MnO2 nanosheets are uniformly deposited on graphenated carbon nanotube networks to construct core-shell heterostructure based on the facile hydrothermal reaction using KMnO4 as the precursor. Core carbon nanotube networks can offer a stable structural backbone and shell MnO2 nanosheets can shorten diffusion paths of ions. The MnO2 nanosheets@graphenated carbon nanotube networks exhibit a high specific capacitance of 575.4 F g−1 (areal capacitance of 274 mF cm−2) at the current density of 0.5 mA cm−2 and good cycling stability (93% of capacity retention after 6000 cycles), due to the synergistic effects between pseudocapacitive MnO2 nanosheets and conductive carbon nanotube networks. The developed synthetic strategy offers design guidelines for the construction of advanced binder-free electrodes for high-performance supercapacitors.

Novel cuboid-like cobalt nickel phosphate/manganese dioxide/multi-walled carbon nanotubes composites as binder-free electrodes for high-performance supercapacitors

Using NiCl2·6H2O, CoCl2·6H2O, Na2HPO4, manganese dioxide (MnO2) and Multi-walled carbon nanotubes (MWCNTs) as the main raw materials, the cuboid-like cobalt nickel phosphate/MnO2/MWCNTs (CNPMM) composites were successfully prepared by a simple hydrothermal method. The morphology, composition and structure of the composites were studied by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectrum, specific surface area analyzer and particle size analysis. SEM images showed that the composite material presented a cuboid-like morphology. The width, length and height of cuboids are 0.3–0.8 µm, 2–3 µm and 8–10 µm, respectively. The special structure and morphology of the sample provide more active sites, making it exhibit superior pseudocapacitance. The electrochemical performance of the three-electrode system supercapacitor was systematically studied by cyclic voltammetry, constant current charge-discharge and electrochemical impedance spectroscopy. When the mass ratio of MnO2 to MWCNTs is 1:1 with the total doping amount of 3.9 wt%, the as-prepared CNPMM1:1 composite shows the best capacitance performance. With 3 mol·L−1 KOH as the electrolyte, it exhibits a specific capacitance as high as 2334 F g−1 at the current density of 1 A g−1. Even at the high current density of 10 A g−1, the specific capacitance can still be maintained at 1672 F g−1, and the corresponding specific capacitance retention of 71.6%, indicating that the composite electrode material has good rate performance. The results show that the cuboid-like CNPMM1:1 composite is a promising electrode material for supercapacitors.

3D hierarchical CuS microflowers constructed on copper powders-filled nickel foam as advanced binder-free electrodes

A novel strategy, consisting of sonication-assisted filling step followed by a chemical-bath surface sulfidization process, was designed to fabricate 3D hierarchical CuS microflowers constructed on copper powders-filled nickel foam (Cu@CuS–NF) as advanced binder-free electrodes for high-performance supercapacitors. Scanning electron microscope, powder X-ray diffraction and X-ray photoelectron spectroscopy techniques were employed to confirm the microstructure and composition. Electrochemical measurements demonstrated that the Cu@CuS–NF electrode has highly improved capacitance with an ultra-high area capacitance of 11.4 F cm−2 at a high current density of 90 mA cm−2. Also, the Cu@CuS–NF electrode has superior cycling stability with more than 100% retention of the initial area capacitance after 3000 cycles at 180 mA cm−2. The excellent electrochemical performance can be mostly attributed to a combination of the ultra-large loading area and very good electroconductive network formed from copper powders filling inside nickel foam. Our work opens a new door to engineering ultra-high-performance nickel-foam-based electrodes for electrochemical devices including water splitting and energy storage/conversion.

3D hierarchical transition-metal sulfides deposited on MXene as binder-free electrode for high-performance supercapacitors

MXene has been considered as a promising two-dimensional material for supercapacitors owing to its large surface area, high conductivity, and excellent cycling stability. However, its low specific capacitance restricts its extensive applications. Therefore, to address the issue, we homogeneously deposited NiCo2S4 nanoflakes on the surface of MXene on conductive nickel foam (denoted as MXene-NiCo2S4@NF), which was used as a composite binder-free electrode for supercapacitor applications. The NiCo2S4 nanoflakes increased the surface area of the composite electrode, thereby increasing its specific capacity from 106.34Cg−1 to 596.69Cg−1 at 1Ag−1. Compared to the pristine MXene, MXene-NiCo2S4@NF maintained the high retention rate of pristine MXene and exhibited excellent cycling stability with 80.4% of its initial specific capacity after 3000 cycles. The composite electrode exhibited improved electrochemical performance for supercapacitors, owing to the combined merits of NiCo2S4 (high specific capacity) and MXene (high retention rate and good cycling stability. The fabricated asymmetric solid-state supercapacitor using MXene-NiCo2S4 as a positive electrode and active carbon as a negative electrode, exhibited an energy density of 27.24Whkg−1 at 0.48kWkg−1 of power density.

Microflower-like nickel sulfide-lead sulfide hierarchical composites as binder-free electrodes for high-performance supercapacitors

Abstract Nickel sulfide (NiS), lead sulfide (PbS) and composite of NiS-PbS hybrid are deposited onto nickel (Ni) foam current collector via a simple and cost-effective chemical bath deposition route and utilized as a binder-free battery-type electrode materials for supercapacitor applications. High-performance NiS and highly-stable PbS electrodes are rationally designed to develop a new class NiS-PbS electroactive material. Surface morphological and structural studies indicate that the NiS-PbS composite exhibits a beautiful morphology of nanosheet based microflower structures. Such hierarchical microflower structures provide abundant Faradic active sites and enable the fast redox reactions. As result, the NiS-PbS composite exhibits a higher specific capacity of 125.89 mA h g−1 at a current density of 2 A g−1 in 3 M KOH electrolyte solution, and it is 1.62 and 2.67 times higher than the bare NiS and PbS electrodes. In addition, NiS-PbS composite delivers excellent cycling stability retaining 88.97% of initial capacitance after 3000 cycles, which is much larger than that of NiS (76.86%) and PbS (82.72%) electrodes. Our results demonstrate that the microflower structured NiS-PbS composites are promising for supercapacitor applications.

Hierarchical zinc cobalt sulfide flowers grown on nickel foam as binder-free electrodes for high-performance asymmetric supercapacitors

In this work, hierarchical zinc cobalt sulfide flowers on nickel foam (f-Zn0.76Co0.24S/Ni foam) are fabricated by a facile two-step hydrothermal method. The obtained f-Zn0.76Co0.24S/Ni foam are directly used as the binder-free electrodes for high-performance supercapacitors. The as-prepared f-Zn0.76Co0.24S/Ni foam exhibite a high specific capacitance of 1906 F g−1 at a current density of 1 A g−1 and good rate performance. The excellent electrochemical performance can be attributed to the unique interconnected flower structure, which provides a path for the rapid diffusion of electrolyte ions. Moreover, the f-Zn0.76Co0.24S/Ni foam//Fe2O3@rGO asymmetric supercapacitor is assembled. It can achieve a high energy density of 75.7 Wh kg−1 at a power density of 700.5 W kg−1 and display superior cycling stability with 86.7% retention after 8000 cycles.

Electrodeposited Ni(OH)2-modified CuS core–shell-like hybrids as binder-free electrodes for high-performance supercapacitors

In this work, binder-free electrodes of CuS@Ni(OH)2 were fabricated by hydrothermal and electrodeposition methods.