Advanced Supercapacitor Electrodes Research Articles

Nitrogen plasma activation of cactus-like MnO2 grown on carbon cloth for high-mass loading asymmetric supercapacitors

The electrochemical performance of high theoretical capacitance MnO2 is usually restricted to low mass loading electrode due to the slower electron/ion diffusion kinetics in dense electrodes. Defect engineering has been supposed to an effective way to improve the capacitive performance of transition metal oxides. Herein, cactus-like structure MnO2 was grown on carbon cloth (CC) and treated with N2-plasma to obtain the N-MnO2 electrode with high mass loading of 12 mg cm−2. Benefiting from the hierarchical structure and rich oxygen vacancies, the as-prepared N-MnO2 electrode delivered a high mass specific capacitance of 443F g−1 and a high areal capacitance of 5320 mF cm−2. Furthermore, the N-MnO2 electrode released an excellent rate capability with 71.8% capacitance retention at 20 mA cm−2 as well as gratifying cycling life with 96 % capacitance retention after 8 000 cycles at 20 mA cm−2. Moreover, an asymmetrical supercapacitor device assembled by N-MnO2 and activated CC can achieve a high energy density of 0.56 mWh cm−2 (46 Wh kg−1) at the power density of 5.14 mW cm−2 (420 W kg−1) with good cycle stability. Such facile N2-plasma treatment for defect engineering shows great potential in the rational design for advanced supercapacitor electrodes with high mass loading.

Rational design of ZIF-8 assimilated hierarchical porous carbon nanofibers as binder-free electrodes for supercapacitors

Recently, tremendous attention has been paid to carbon-based fibers, particularly porous carbon fibers (PCFs), because of their great potential as electrodes for advanced supercapacitors (SCs). However, the relatively complex preparation and monotonous pore structure are still the most important challenge that PCFs needs to counter. In this work, an eco-friendly yet facile approach has been applied to synthesis PCFs with tunable multi-level pores and satisfactory electrochemical performance. By using the combinations of electrospinning technology, hard-template method and carbonization process, nanofibers with interconnected multi-level pores can be achieved. It is demonstrated that the pore engineered PCF possesses enhanced electrochemical performance. For instance, the PCF electrode possesses a high capacitance of 211 F g−1 in 6 mol L−1 KOH at a density of 0.5 A g−1 together with excellent rate capability. Meanwhile, a high areal capacitance of 1.2 F cm−2 also can be achieved at a mass loading of 10 mg cm−2. Additionally, symmetrical supercapacitor assembled by PCF electrodes exhibits good capacitance of 101.9 F g−1 at the current density of 0.5 A g−1, such device also can deliver an energy density up to 60.1 Wh kg−1 with ionic liquid electrolyte.

Dual-Redox-Sites Enable Two-Dimensional Conjugated Metal-Organic Frameworks with Large Pseudocapacitance and Wide Potential Window.

Advanced supercapacitor electrodes require the development of materials with dense redox sites embedded into conductive and porous skeletons. Two-dimensional (2D) conjugated metal-organic frameworks (c-MOFs) are attractive supercapacitor electrode materials due to their high intrinsic electrical conductivities, large specific surface areas, and quasi-one-dimensional aligned pore arrays. However, the reported 2D c-MOFs still suffer from unsatisfying specific capacitances and narrow potential windows because large and redox-inactive building blocks lead to low redox-site densities of 2D c-MOFs. Herein, we demonstrate the dual-redox-site 2D c-MOFs with copper phthalocyanine building blocks linked by metal-bis(iminobenzosemiquinoid) (M2[CuPc(NH)8], M = Ni or Cu), which depict both large specific capacitances and wide potential windows. Experimental results accompanied by theoretical calculations verify that phthalocyanine monomers and metal-bis(iminobenzosemiquinoid) linkages serve as respective redox sites for pseudocapacitive cation (Na+) and anion (SO42-) storage, enabling the continuous Faradaic reactions of M2[CuPc(NH)8] occurring in a large potential window of -0.8 to 0.8 V vs Ag/AgCl (3 M KCl). The decent conductivity (0.8 S m-1) and high active-site density further endow the Ni2[CuPc(NH)8] with a remarkable specific capacitance (400 F g-1 at 0.5 A g-1) and excellent rate capability (183 F g-1 at 20 A g-1). Quasi-solid-state symmetric supercapacitors are further assembled to demonstrate the practical application of Ni2[CuPc(NH)8] electrode, which deliver a state-of-the-art energy density of 51.6 Wh kg-1 and a peak power density of 32.1 kW kg-1.

Zephyranthes-like Co2NiSe4 arrays grown on 3D porous carbon frame-work as electrodes for advanced supercapacitors and sodium-ion batteries

Zephyranthes-like Co2NiSe4 arrays grown on 3D porous carbon frame-work as electrodes for advanced supercapacitors and sodium-ion batteries

Three-dimensional polypyrrole-enhanced flower-like ZnCo2S4 nanoclusters used as advanced electrodes for supercapacitors

Confinement transition metal compounds with conducting polymer is an effectively to inhibit the volume change during the Faradic reaction. In this work, three-dimensional flower-like polypyrrole-wrapped ZnCo2S4 (ZnCo2S4@PPy) core-shell nanoclusters were successfully prepared by two-step hydrothermal and electrochemical deposition methods. The obtained ZnCo2S4@PPy composite exhibited remarkable electrochemical performance corresponding to a specific capacitance of 1486 F g−1 at 1 A g−1, which suggested its potential use as a supercapacitor electrode material. Furthermore, the asymmetric supercapacitor containing a ZnCo2S4@PPy positive electrode demonstrated a high specific energy of 33.78 Wh kg−1 at 800.05 W kg−1 and relatively long cycle life (90% capacitance retention after 5000 cycles). The excellent electrochemical performance of ZnCo2S4@PPy can be attributed to the synergistic effect of its main components and unique flower-like core-shell structure. The results reveal that the ZnCo2S4@PPy core-shell nanocluster array is a promising electrode material for future energy-storage devices.

Bimetallic Co0.4Ni1.6P derived from cobalt functionalized a new nickel metal-organic-framework as an advanced electrode for high-performance supercapacitors

A new nickel metal organic framework (MOF) based on 4-cyan-5-acidamide-bisimidazole were fabricated using hydrothermal method. The Co@Ni-MOFwasprepared by doping Ni-MOF with Co2+through post-synthetic modification method. The bimetallic Co0.4Ni1.6P was obtained through phosphorization of Co@Ni-MOF and showed high specific capacity 330F/g at 1 A/g and capacity retention was 96% over 5000 cycles. The supercapacitor device was prepared (Co0.4Ni1.6P//AC) and demonstrated specific energy of 30.9 Wh/kg at power of 806 W/kg. These results provided a new way to design bimetallic phosphide (MOF-based materials) for supercapacitor application.

Core−shell coaxially structured NiCo2S4@TiO2 nanorod arrays as advanced electrode for solid-state asymmetric supercapacitors

An integrated electrode of core–shell coaxially structured NiCo2S4@TiO2 nanorod arrays/carbon cloth (NiCo2S4@TiO2@CC) have been fabricated, via a two-step hydrothermal method. Comprehensive structural and compositional analyzes are performed to understand the effects of the NiCo2S4 shell on the TiO2 core. Such core–shell arrays structure can significantly provide abundant electroactive sites for redox reactions, convenient ion transport paths, and favorable structure stability. The NiCo2S4@TiO2@CC electrode represents a splendid specific capacitance (650 F g−1 at 1 A g−1) and enhanced cycling stability (capacitance retention of 97% over 10 000 cycles at 5 A g−1). Additionally, the assembled NiCo2S4@TiO2@CC//CNT@CC solid-state asymmetric supercapacitors exhibit a maximal energy density of 0.6 mWh cm−3 at 32.4 W cm−3, and topping cycling stability (85% capacitance retention after 5000 cycles at 5 mA cm−2). The results demonstrate that the well-designed NiCo2S4@TiO2@CC presented in this work are applicable for the development of electrode materials in energy storage devices.

Assembling Co3O4 Nanoparticles into MXene with Enhanced electrochemical performance for advanced asymmetric supercapacitors

MXenes with unique 2D open structure, large surface-area-to-volume ratios, high pseudo-capacitance, and conductivity are attractive for advanced supercapacitor electrodes. However, the restacking issue of MXenes hinders ion accessibility, resulting in the reduction of volume performance, mass load, and speed capability. To address these issues, a facile hydrothermal synthesis strategy is proposed to fabricate Co3O4 nanoparticles-MXene (Co-MXene) composite by the self-assembly process. Co3O4 nanoparticles, introduced in the MXene matrix, effectively prevent self-restacking and shorten ion/electron transport paths. Consequently, the obtained Co-MXene electrode delivers the high-performance of 1081F g−1 at a current density of 0.5 A g−1, surpassing the pristine MXene electrode (89F g−1 at 0.5 A g−1). Being assembled into asymmetric supercapacitors (ASC), a high energy density of 26.06 Wh kg−1 at 700 W kg−1 was realized. After 8000 cycles, the ASC device maintains 83% of initial specific capacitance at 2 A g−1. This work highlights a simple and efficient method for developing high-performance MXene-based electrodes for supercapacitors.

Construction of core-shell Ni@Ni3S2@NiCo2O4 nanoflakes as advanced electrodes for high-performance hybrid supercapacitors

A universal strategy was used to synthesize the core-shell structure Ni@Ni3S2@NiCo2O4 nanoflakes. As wished, benefiting from the core-shell structure of nanoflakes, the as-synthesized Ni@Ni3S2@NiCo2O4 electrode materials show excellent electrochemical performance. Furthermore, the effect of ethylenediamine on the electrochemical performances of the Ni@Ni3S2@NiCo2O4 nanoflakes was studied. In a three-electrode system, the specific capacitance achieves 13.4 F cm−2 at a current density of 1 mA cm−2 and even 11.7 F cm−2 at 10 mA cm−2. Moreover, the fabricated hybrid supercapacitor was assembled using Ni@Ni3S2@NiCo2O4 as a positive electrode, the activated carbon (AC) as a negative electrode, and KOH as an electrolyte, respectively. The assembled device delivers an energy density of 57 Wh∙kg−1 at a power density of 3700 W kg−1 and good cycling stability (82% capacitance retention after 8000 cycles), demonstrating its excellent energy storage property in supercapacitor.

High-Mass-Loading Electrodes for Advanced Secondary Batteries and Supercapacitors

The growing demand for advanced electrochemical energy storage systems (EESSs) with high energy densities for electric vehicles and portable electronics is driving the electrode revolution, in which the development of high-mass-loading electrodes (HMLEs) is a promising route to improve the energy density of batteries packed in limited spaces through the optimal enlargement of active material loading ratios and reduction of inactive component ratios in overall cell devices. However, HMLEs face significant challenges including inferior charge kinetics, poor electrode structural stability, and complex and expensive production processes. Based on this, this review will provide a comprehensive summary of HMLEs, beginning with a basic presentation of factors influencing HMLE electrochemical properties, the understanding of which can guide optimal HMLE designs. Rational strategies to improve the electrochemical performance of HMLEs accompanied by corresponding advantages and bottlenecks are subsequently discussed in terms of various factors ranging from inactive component modification to active material design to structural engineering at the electrode scale. This review will also present the recent progress and approaches of HMLEs applied in various EESSs, including advanced secondary batteries (lithium-/sodium-/potassium-/aluminum-/calcium-ion batteries, lithium metal anodes, lithium-sulfur batteries, lithium-air batteries, zinc batteries, magnesium batteries) and supercapacitors. Finally, this review will examine the challenges and prospects of HMLE commercialization with a focus on thermal safety, performance evaluation, advanced characterization, and production cost assessment to guide future development.

Hierarchical CuCo2O4/CuO nanoflowers crosslinked with carbon nanotubes as an advanced electrode for supercapacitors

The emerging CuCo2O4 is a promising electrode material for supercapacitors, while the low conductivity and volume expansion limit the specific capacity and rate performance. Here, a facile solvothermal method is used to synthesize hierarchical flower-like CuCo2O4/CuO. Then the CuCo2O4/CuO that crosslinked with carbon nanotubes could form a 3D conductive network and lead to a superior electrochemical performance. As-prepared material CuCo2O4/CuO/carbon nanotubes exhibit a specific capacitance of 1084 F g−1 at 2 A g−1 and excellent cycling stability of 97.8% retention after 9000 cycles. Moreover, the assembled asymmetric supercapacitor coupled with active carbon demonstrates an extraordinary cycling stability (86.8% after 9000 cycles).

RETRACTED ARTICLE: Fabrication of hexagonal shaped CuCo2S4 nanodiscs/graphene composites as advanced electrodes for asymmetric supercapacitors and dye sensitized solar cells (DSSCs)

RETRACTED ARTICLE: Fabrication of hexagonal shaped CuCo2S4 nanodiscs/graphene composites as advanced electrodes for asymmetric supercapacitors and dye sensitized solar cells (DSSCs)

Synthesis of nitrogen-doped porous carbon and partial poly (2, 2′-dithiodianiline) composite as advanced supercapacitor electrode materials

Composited materials (NC/PDTDA) of nitrogen-doped porous carbon (NC) and partial poly (2, 2′-dithiodianiline) (PDTDA) have been successfully synthesized by in-situ polymerization and can be utilized in alkaline electrolytes as electrodes for supercapacitors. The physiochemical properties of NC/PDTDA composites materials are characterized by field emission scanning electron microscope, transmission electron microscope, Fourier transform infrared spectroscopy, Raman spectrum, X-ray electron spectrum, and X-ray diffraction. In addition, the electrochemical properties of NC/PDTDA composites materials are tested in 3 M KOH aqueous solution with a representative three-electrode system. It shows the highest specific capacitance when the mass ratio of NC to PDTDA is 1:2 (NC/PDTDA-2), and the specific capacitance is 490.5 F/g at a current density of 1 A/g. More significantly, the asymmetric supercapacitor is also assembled with an extended operating voltage window of 1.4 V in PAM-PVA- KOH electrolyte. It exhibits an energy density of 13.49 Wh/Kg at a power density of 699.8 W/Kg.

Induced conducting energy-levels in a boron nitride nano-framework for asymmetric supercapacitors in high charge-mobility ionic electrolytes

Boron nitride's (BN) large band gap does not permit carrier transport at ambient conditions. We show that BN sheets can be exfoliated by functionalization with oxy-groups to introduce additional acceptor and donor energy levels appropriate for energy storage devices. Further, the incorporation of heteroatoms into transition metal sulfides enhances capacitance via Faradic redox reactions and their cyclic stability. The functionalized boron nitride (mK-BN) and Carbon Nanotubes (CNTs) are intertwined with a Zn-doped Cadmium-Sulfide (Zn–CdS) nanostructure to increase the surface area-charge storage. In a supercapacitor application, Zn–CdS/mK-BN/CNT exhibits a 787 F/g specific capacitance (SC) in an aqueous (aq.) electrolyte. Further, the Zn–CdS/mK-BN/CNT was deployed as a cathode material in an asymmetric supercapacitor device (ASC) coupled with an ionic electrolyte (IE), (NHEt3)+(NO3)−, offered a SC of 173 F/g with an approximate 99% stability due to the enhanced charge mobility. The reported functionalization of BN induces additional energy levels making the material ideal for energy storage devices and will directly impact the next-generation of advanced supercapacitor electrode materials.

Al(NO3)3 Induced Morphological Changes in Nickel and Cobalt Salts as Advanced Electrodes for Supercapacitors

Abstract As one of the important components of the supercapacitor, electrode material has a significant influence on the electrochemical performance of the device. In this study, Ni2(NO3)2(OH)2 · 2H2O/(Co(NH3)5(N3))(N3)2 (NC) composite material was prepared by the microwave-assisted method. The effects of Al(NO3)3 contents on the morphology and structure of the composites were studied by scanning electron microscopy, X-ray diffraction, Raman spectrum, and laser particle size distribution analyzer. The capacitive properties of the composite were analyzed by cyclic voltammetry, constant current charge and discharge, and electrochemical impedance spectroscopy measurements. The results show that the Al(NO3)3 has a significant effect on the morphology and capacitance of NC. When the contents of Al(NO3)3 are 0, 5, 10, 15, and 20 wt%, the discharge capacities of NC, NCA-5, NCA-10, NCA-15, and NCA-20 samples obtained under 1 A/g current density are 1674, 1759, 2645, 1098, and 1321 F/g, respectively. At higher current densities of 4, 7, and 10 A/g, the discharge specific capacities reached 1350, 1064, and 894 F/g, indicating that the NCA-10 composite is a promising electrode material for supercapacitors.

Hierarchically novel bead-curtain-like zinc-cobalt sulfides arrays toward high energy density hybrid supercapacitors via morphology engineering

Rational design of the electrode materials in distinctive architecture and tailored composition is critical for regulating their electrochemical properties. Herein, the novel porous zinc-cobalt sulfides (ZCS) bead-curtain-like arrays (BCA) supported by three-dimensional Ni foam (NF) (denoted as ZCS/NF BCA) are fabricated as advanced electrode for supercapacitors (SCs), which exhibit remarkable electrochemical performances in respect of superb capacity of ~837 C g−1 (specific capacitance of ~1860 F g−1) at 1 A g−1 and ultra-long cycling stability (~92.9% retention after 5000 cycles at 6 A g−1). Furthermore, the assembled hybrid supercapacitors based on ZCS/NF BCA delivers ultrahigh energy density of ~88 Wh kg−1 with a maximum power density of ~800 W kg−1. The excellent properties may be ascribed to the combined contributions from the hierarchical bead-curtain architecture of ZCS/NF BCA composite and the bimetallic sulfide with abundant valence states for rich redox reactions.

Fabrication coralline Ni-Mo-O-S composites as advanced electrodes for high-performance asymmetric hybrid supercapacitors

In this work, the coralline nickel molybdenum oxide and sulfide (Ni-Mo-O-S) composites were successfully synthesized by two-step hydrothermal method. The coralline structure has large specific surface area and enriched porosity, which makes the composites have excellent electrical conductivity. Furthermore, the synergistic effect of Ni and Mo elements and the addition of S2− ions improved the electrical conductivity and electrochemical performance of Ni-Mo-O-S. The electrochemical performance of the prepared materials was evaluated in detail. Specifically, the Ni-Mo-O-S composites achieved a high specific capacity of 330.2 mA h/g (3714.4 F/g) at a current density of 1 A/g, even 317.5 mA h/g (3265.5 F/g) at 5 A/g, as well as showing good rate performance and improved cyclic stability (75% capacitance retention after 3000 cycles). The asymmetric supercapacitor device assembled from Ni-Mo-O-S as the cathode and active carbon as the anode had a high specific energy of 35 Wh/kg at a specific power of 903.2 W/kg, and possessed excellent long-term electrochemical cycling stability (95.2% capacitance retention after 10,000 cycles). These results indicate that our coralline composites provide a promising and feasible method for the development of supercapacitors.

Application of Octanohydroxamic Acid for Salting out Liquid-Liquid Extraction of Materials for Energy Storage in Supercapacitors.

The ability to achieve high areal capacitance for oxide-based supercapacitor electrodes with high active mass loadings is critical for practical applications. This paper reports the feasibility of the fabrication of Mn3O4-multiwalled carbon nanotube (MWCNT) composites by the new salting-out method, which allows direct particle transfer from an aqueous synthesis medium to a 2-propanol suspension for the fabrication of advanced Mn3O4-MWCNT electrodes for supercapacitors. The electrodes show enhanced capacitive performance at high active mass loading due to reduced particle agglomeration and enhanced mixing of the Mn3O4 particles and conductive MWCNT additives. The strategy is based on the multifunctional properties of octanohydroxamic acid, which is used as a capping and dispersing agent for Mn3O4 synthesis and an extractor for particle transfer to the electrode processing medium. Electrochemical studies show that high areal capacitance is achieved at low electrode resistance. The electrodes with an active mass of 40.1 mg cm−2 show a capacitance of 4.3 F cm−2 at a scan rate of 2 mV s−1. Electron microscopy studies reveal changes in electrode microstructure during charge-discharge cycling, which can explain the increase in capacitance. The salting-out method is promising for the development of advanced nanocomposites for energy storage in supercapacitors.

Microwave assisted growth of MnO2 on biomass carbon for advanced supercapacitor electrode materials

Microwave assisted growth of MnO2 on biomass carbon for advanced supercapacitor electrode materials

Fast and scale-up synthesis of amorphous C,N co-doped mesoporous Co-based phosphates as advanced electrodes for supercapacitors and water oxidation

Convenient and green methods to synthesize highly efficient and stable multi-functional electrode materials are the key and a challenge for the industrial application of new energy conversion devices.