Aqueous Asymmetric Supercapacitor Research Articles

Rational design of the binder-free polythiophene nanofibers deposited nickel foam for the high-performance aqueous asymmetric supercapacitor

Development of the binder-free electrode materials and employing in the supercapacitor is the essential footstep for high energy storage. The present study highlights the cost-effective synthesis strategy for the binder-free growth of the amorphous polythiophene nanofibers over the nickel foam substrate. The presence of functional bonds like CC, C-H, and C-S has confirmed the deposition of the polythiophene nanofibers on the nickel foam, while elemental mapping analysis detected the uniform distribution of Carbon and Sulfur elements over nanofibers. The surface structure of the polythiophene is transformed from nanofibers to a wire-like structure as the result of the monomer concentration variation. The optimized polythiophene film exhibited the highest areal capacitance of 1263.2 mF/cm2 at 2 mA/cm2 with 90.03% capacitance retention after 5000 cycles. Moreover, the aqueous asymmetric device (PTh//AC) is fabricated which delivered 31.5 F/g at 10 mA/cm2. The highest specific energy of PTh//AC device was 6.3 Wh/kg. Also, it showed good retention capability with 82.3% retention. Based on these results, the present investigation provides the performance metrics of the polythiophene nanofibers and highlights the potential utilization of the polythiophene-based supercapacitor in practical energy storage systems.

Successful In Situ Growth of Conductive MOFs on 2D Cobalt-Based Compounds and Their Electrochemical Performance.

Conductive metal-organic frameworks (cMOFs), as a kind of porous material, are considered to be highly promising materials in the field of electrochemistry due to their excellent conductivity. However, due to the low specific capacitance of pure cMOFs, their application in supercapacitors is limited. By virtue of the high theoretical capacity and excellent chemical stability of Co-based compounds, in this work, cMOFs' M-HHTP (M = Ni, Co, NiCo, HHTP = 2,3,6,7,10,11-hexahydroxytriphenylene) are grown in situ on Co(OH)2, CoP, and Co3O4 nanosheets, resulting in a series of electroactive compounds as electrode materials used in supercapacitors. Among all of the compounds, Ni-HHTP@Co(OH)2 shows the most excellent energy storage performance and outstanding cyclic stability in the application of aqueous asymmetric supercapacitors.

Enhanced Energy Storage Performance through Controlled Composition and Synthesis of 3D Mixed Metal-Oxide Microspheres.

Binary transition metal oxide complexes (BTMOCs) in three-dimensional (3D) layered structures show great promise as electrodes for supercapacitors (SCs) due to their diverse oxidation states, which contribute to high specific capacitance. However, the synthesis of BTMOCs with 3D structures remains challenging yet crucial for their application. In this study, we present a novel approach utilizing a single-step hydrothermal technique to fabricate flower-shaped microspheres composed of a NiCo-based complex. Each microsphere consists of nanosheets with a mesoporous structure, enhancing the specific surface area to 23.66 m2 g-1 and facilitating efficient redox reactions. When employed as the working electrode for supercapacitors, the composite exhibits remarkable specific capacitance, achieving 888.8 F g-1 at 1 A g-1. Furthermore, it demonstrates notable electrochemical stability, retaining 52.08% capacitance after 10,000 cycles, and offers a high-power density of 225 W·kg-1, along with an energy density of 25 Wh·kg-1, showcasing its potential for energy storage applications. Additionally, an aqueous asymmetric supercapacitor (ASC) was assembled using NiCo microspheres-based complex and activated carbon (AC). Remarkably, the NiCo microspheres complex/AC configuration delivers a high specific capacitance of 250 F g-1 at 1 A g-1, with a high energy density of 88 Wh kg-1, for a power density of 800 W kg-1. The ASC also exhibits excellent long-term cyclability with 69% retention over 10,000 charge-discharge cycles. Furthermore, a series of two ASC devices demonstrated the capability to power commercial blue LEDs for a duration of at least 40 s. The simplicity of the synthesis process and the exceptional performance exhibited by the developed electrode materials hold considerable promise for applications in energy storage.

Preparation of Positive and Negative Composite Electrode Materials for High-Performance Aqueous Asymmetric Supercapacitor by a Sequential Two-Step Reaction

Preparation of Positive and Negative Composite Electrode Materials for High-Performance Aqueous Asymmetric Supercapacitor by a Sequential Two-Step Reaction

Facile synthesis of flower-like NiCo/NiO–CoO surrounded by N-doped porous carbon derived from covalent organic framework for aqueous asymmetric supercapacitor

The persisting quest for improving charge density, electronic conductivity and cyclic stability of the electrode material in supercapacitor (SC) applications still demands intensive research and advancements. This study also aims the aforementioned pursuit with the construction of hybrid supercapacitor using mixed metal oxides with the incorporation of metal and supported with porous carbon to improve the charge density, electrical conductivity and cyclic stability, respectively. A covalent organic framework (COF) was synthesized and doped with nickel (Ni2+) and cobalt (Co2+) ions followed by carbonization at 1000 °C for 3 h to generate NiCo/NiO–CoO surrounded N-doped porous carbon (NPC) framework. The X-ray diffraction reveals that nickel considerably impacts the crystallinity of NiCo/NiO–CoO and the Raman spectroscopy revealed that the NiCo/NiO-CoO-NPC with an equal molar ratio of Ni2+ and Co2+ ions (NiCo/NiO-CoO-NPC-2) offered the highest degree of graphitization. The electron microscopic images showed the formation of flower-like morphology of NiCo/NiO-CoO-NPC-2 with a size of 250 nm and the greater number of flowers on NPC's surface could augment the electrochemical activity of the composite material. The NiCo/NiO–CoO-NPC-2 offered an attractive specific capacitance (Cs) of 845 F g−1 @ 1 A g−1 and preserves 93% capacity retention @ 10 A g−1 after 6000 charge-discharge cycles while exploited in SC application. The metal-free COF carbonized at 900 °C (CCOF-900) is utilized as the negative electrode with a Cs of 286 F g−1 @ 1 A g−1 for the construction of an asymmetric supercapacitor device and the NiCo/NiO-CoO-NPC-2//CCOF-900 device delivered efficient energy of 54 Wh kg−1 at a power density of 633 W kg−1.

Microwave construction of the 3D porous interconnected structure of NiCoCr medium-entropy alloy with ultra-high specific capacity for supercapacitors and electrocatalysis

The effective design of bifunctional electrodes with unique morphology and remarkable electrochemical properties for energy conversion and storage devices is a promising but challenging endeavor. Herein, self-supporting NiCoCr medium-entropy alloy (MEA) with a hierarchical porous network structure was in situ synthesized on nickel foam (NiCoCr/NF) by a simple and rapid microwave route. The optimal NiCoCr/NF presented an ultra-high specific capacity of 3011.8 C g−1 (1 A g−1) and outstanding charge/discharge sustainability (83.4% retention at 10 A g−1 over 50,000 cycles) due to its multi-component synergistic effect and hierarchical porous structure. Meanwhile, subtle lattice distortions and electron density redistribution in the NiCoCr MEA tuned electronic structures, resulting in a low overpotential and Tafel slope. Aqueous and solid-state asymmetric supercapacitors were fabricated by using NiCoCr/NF as a cathode and Bi/NF as an anode. The aqueous supercapacitor displayed an exceptional energy density of 314.4 Wh kg−1 at a power density of 800 W kg−1 with 81.8% retention at 10 A g−1 over 20,000 cycles. This study provides a new strategy for the efficient synthesis of electrode materials with interconnected network structures and paves the way for the broader application based on medium-entropy and high-entropy materials as promising candidates for future energy storage devices.

Highly matched porous MXene anodes and graphene cathodes for high-performance aqueous asymmetric supercapacitors

Aqueous asymmetric supercapacitors (ASCs) provide promising prospects for electronic systems in the future that require high energy density, power density and cycling life, due to their advantages such as low cost, safe operation and environmental friendliness. However, developing well-matched anodes and cathodes with complementary potential windows and coordinated charge storage kinetics remains a significant challenge. Here, we constructed porous MXene- and graphene-based films with nitrogenous and phosphorous terminals as anodes and cathodes, respectively, alleviating the restacking of nanosheets, generating more electrochemical active sites and improving the electrolyte penetration. The assembled aqueous ASCs based on the porous MXene and graphene films could achieve an excellent energy density of 26.8 Wh kg−1 at 425 W kg−1, high rate performance, and remarkable cycling stability with 97.3 % retention after 20,000 cycles. This work demonstrates a novel concept to develop high-performance aqueous ASCs by surface engineering of two-dimensional porous electrodes with matched structural and electrochemical properties.

Simple preparation of V-doped NiCo-LDH as cathode of high energy density supercapacitor

One of the most promising cathode materials for supercapacitors is nickel-cobalt layered double hydroxide (NiCo-LDH). Doping atoms are widely used to solve the problems of poor electrical conductivity and structural defects of electrode materials. Vanadium (V) has received widespread attention due to its multiple oxidation states and low cost. In this article, we use one-step hydrothermal method to synthesize V-doped NiCo-LDH (V-NC1.5). By regulating the doping amount of V, 2V-NC1.5 exhibits superb specific capacitance of 1835 F g−1 at 1 A g−1. An asymmetric aqueous supercapacitor was assembled with 2V-NC1.5 and activated carbon. Its maximum energy density can reach 60.9 Wh kg−1 at 800 W kg−1 of power density. When the two units are connected in series, they can effectively power a white LED bulb and maintain its brightness for more than 30 min. This result provides a potential opportunity for the efficient deployment of innovative energy storage technologies in the coming years.

Metastable 2D amorphous Nb2O5 for aqueous supercapacitor energy storage

Nb2O5 is a promising electrode material of energy storage due to its high specific capacity and phase transition resistance. However, the facile generation of niobic acid poses a challenge, hindering controlled growth and impeding improvements in electrical conductivity and structural stability, especially in realizing two-dimensional (2D) Nb2O5. Herein, we have discerned that the addition of hexamethylenetetramine (HMTA) in ethanol solvent facilitates the controlled and restricted growth of metastable 2D amorphous Nb2O5 (a-Nb2O5) within graphene domains. Nitrogen atoms within HMTA, rich in lone pair electrons, strongly interact with niobium ions, promoting 2D amorphous growth on graphene interface. This unique 2D amorphous interface offers high surface area, enhanced electron mobility, rapid ion transport, and superior structural stability compared to crystalline counterparts. The prepared metastable 2D a-Nb2O5/rGO electrode exhibits unprecedented cycle life in aqueous asymmetric supercapacitor. This confined growth strategy offers a novel approach for the innovative design of metastable 2D materials.

Aqueous Asymmetric Supercapacitors with Pyrenetetraone‐Derived Pseudocapacitive Polymer‐Functionalized Graphene Cathodes Enabling a 1.9 V Operating Window

Aqueous Asymmetric Supercapacitors with Pyrenetetraone‐Derived Pseudocapacitive Polymer‐Functionalized Graphene Cathodes Enabling a 1.9 V Operating Window

Highly efficient alkaline aqueous MXene-based asymmetric supercapacitors developed by corrugation-like MoS2 and WS2 modified CMX electrodes

The preparation of superior performance supercapacitors to achieve high energy density, fast charge-discharge speed and long cycle stability characteristics has become the focus of attention to realize their potential as practical energy storage devices. In this paper, a cross-linking CNTs@MXene (CMX) architecture is selected as the negative electrode to increase the contact area with electrolyte, and corrugation-like morphologies MoS2 and WS2 nanoparticles modified CMX (Mo/W-CMX) two-dimensional nanostructure as the positive electrode to provide multiple ion diffusion through its channels structure, which presents good electrochemical performance with high specific capacitance and high energy density in 1 M KOH alkaline electrolyte. CNTs introduced into MXene interface by bridges can effectively impede the re-stacking of MXene, meanwhile, CMX as a matrix can also alleviate the properties degradation caused by the agglomeration and volume strain for sulfides. Benefiting from the facilitate accessibility of ions and high ability of electron transfer, the prepared Mo/W-CMX electrode exhibits a dramatic specific capacitance of 1160 F g−1 at 1 A g−1 and excellent capacitance retention of 88.67% at 25 A g−1 after 10,000 cycles. Meanwhile, the assembled asymmetric supercapacitor (Mo/W-CMX // CMX) presents an ultrahigh energy density of 28.1 Wh kg−1 at the power density of 697.3 W kg−1 and maintains 81.25% cycle stability at 15 A g−1 for 10,000 charge-discharge cycles. It is essential to highlight that the superior performance fabricated asymmetric supercapacitor holds a wide application prospect and very competitive energy-storage values in the upgrading of new high-performance devices.

High-Potential Aqueous Asymmetric Supercapacitor Based on 2D Molybdenum Disulfide and Vanadium Pentoxide Electrodes

High-Potential Aqueous Asymmetric Supercapacitor Based on 2D Molybdenum Disulfide and Vanadium Pentoxide Electrodes

Enhanced electrochemical performance of Co-V-O-N by a synergistic effect for aqueous asymmetric supercapacitors

Insufficient utilization, low conductivity and sluggish kinetics of Co and V-based oxides usually hinder their practical application in supercapacitors. In this study, we employ a simple two-step hydrothermal process to obtain Co-V binary metal composites (Co-V-O-N, a composite comprising CoVO3, VO2(H2O)0.5, (NH4)0.38V2O5, NH4V10O25·8H2O). After optimizing the reaction time between the Co-based precursor (CH) and the subsequently grown V species, the optimal synergistic combination of these two components effectively avoids the agglomeration of the active materials and enhances the conductivity of electrode conductivity. Accordingly, the obtained CH-V16 electrode achieves a high areal capacitance of 6.26F cm−2 at 10 mA cm−2, excellent rate capability with 67 % capacitance retention when the current density is increased from 5 to 60 mA cm−2, much better than the electrodes only with one component. In addition, an asymmetric supercapacitor constructed with CH-V16 and conductive carbon cloth shows a high energy density of 0.347 mWh cm−2 at 4 mW cm−2 as well as impressive cyclic performance by remaining 90 % of the initial specific capacitance over 20,000 cycles at 30 mA cm−2. This work offers a perspective to design high-performance Co-V binary metal oxides for asymmetric supercapacitors by a synergistic combination.

Hierarchical high K content birnessite MnO2 nanosheet arrays as high capacity cathode for asymmetric supercapacitor with broaden potential window of 2.6 V

High specific capacitance and energy density for energy storage devices are dependent on the types of electrodes selection and operational working potential windows. Birnessite MnO2 is reported as the astounding material to show strong electrochemical performances due to it's widen inter-planar spacing, capable to accommodate the alkaline ions for the better outcomes. Herein this article, high K content Birnessite MnO2 nanosheet arrays at carbon cloth substrate (K0.46MnO2 NSAs@CC) are successfully fabricated to optimize its structural, morphological and electrochemical performances as cathode for supercapacitors (SCs). K0.46MnO2 NSAs@CC is operated at broaden potential window from 0 to 1.3 V to achieve excellent specific capacitance of ∼375 F g−1. Reported broaden potential window provides the opportunity for the construction of aqueous asymmetric supercapacitors (ASC) to operate above 2.0 V. For the construction of efficient ASC, Bi2S3 nanoflakes interconnected nanosheets at carbon cloth (Bi2S3 NFNS@CC) are synthesized as anode capable to operate at negative (−1.3 to 0 V) potential window. The 2.6 V ASC is constructed by K0.46MnO2 NSAs@CC as cathode and Bi2S3 NFNS@CC as an anode (K0.46MnO2 NSAs@CC//Bi2S3 NFNS@CC). K0.46MnO2 NSAs@CC//Bi2S3 NFNS@CC as ASC is presenting excellent energy density of ∼72 Wh kg−1 on top of outstanding cycle performance and rate capability compatible with the earlier reported MnO2-based ASCs. This work is elaborating the new guidelines for novel electrode materials scheme and possibilities to achieve broaden potential windows capable to be utilized in practical devices.

Rational design of crystalline/amorphous nickel manganese phosphate octahydrate heterostructure for high-performance aqueous and all-solid-state asymmetric supercapacitors

Designing a rational architecture and combining diverse metal cations are of vital importance to obtain high-performance bimetallic compounds for energy storage purposes. Herein, a novel crystalline/amorphous nickel manganese phosphate octahydrate heterostructure grown in-situ on nickel foam was synthesized by a facile hydrothermal method followed by annealing in argon. The composite exhibits exceptional performance by adjusting the atomic ratio of redox metals (nickel and manganese) with multiple oxidation states. Specifically, the composite shows an excellent specific capacitance of 2351.6 F g−1 at a current density of 1 A g−1 and 67.3 % capacity retention after 3000 cycles at 10 A g−1. This remarkable performance can be attributed to the unique heterogeneous structure of the composite and the synergistic effect between two metals, improving the electronic conductivity. Density functional theory (DFT) calculations further confirm the reduction of band gap and conductivity enhancement. Furthermore, the crystalline portions offer not only active sites but also good mechanical support, while the amorphous components effectively promote ion diffusion and reaction. An aqueous asymmetric supercapacitor was assembled employing nickel manganese phosphate octahydrate as cathode and active carbon as anode, displaying a high energy density of 66.22 Wh kg−1 at a power density of 400 W kg−1 and outstanding cycling performance at 60 mA cm−2 (81.03 % capacitance retention after 15,000 cycles). Additionally, the fabricated all-solid-state asymmetric supercapacitor also displays a remarkable electrochemical performance.

High-performance aqueous asymmetric supercapacitors with a cathode of MnCo2O4 nanowires sandwiched by NiCoMnS4 nanosheets on Ni foam

High-performance aqueous asymmetric supercapacitors with a cathode of MnCo2O4 nanowires sandwiched by NiCoMnS4 nanosheets on Ni foam

Sodium‐Substituted Tungsten Oxide Nanoflowers: An Efficient Electrode Enhancing the Pseudocapacitive Storage in Aqueous Asymmetric Supercapacitors

AbstractElectrode materials engineering at the nanoscale is essential to improve the electrochemical performance for next‐generation energy storage devices. Herein, a novel approach of sodium substitution in the tungsten oxide matrix is highligting the enhancement of the pseudocapacitor performance of the electrode in an aqueous asymmetric supercapacitor. The sodium‐substituted tungsten trioxide (NWO) and pristine tungsten oxide (PWO) nanoflowers prepared by a single‐step hydrothermal process has presented. The tetragonal crystal structure and nanoflower morphology has maintained even after Na substitution. The electrochemical properties of PWO and NWO have investigated with three‐electrode setups in 1 M H2SO4 aqueous electrolyte. The specific capacitance of PWO and NWO exhibits 104 F g−1 and 476 F g−1 at 1 A g−1, respectively. Furthermore, an aqueous asymmetric supercapacitor (AAS) of NWO demonstrates a specific capacitance of 41 F g−1, an energy density of 13 W h kg−1, and a power density of 3750 W kg−1. An excellent stability of AAS has achieved with 100 % capacitance retention from 1000 to 5000 cycles. The sodium substitution significantly enhanced the pseudocapacitive behavior, attributed to enhanced electroactive sites, conductivity, surface area, and chemical stability. It shows the potential of NWO nanoflowers as a promising candidate for next‐generation supercapacitor devices.

A high valence binary metal-organic framework as an electrode material for aqueous asymmetric supercapacitors.

This study presents the chemical transformation of nickel-based metal-organic frameworks into binary metal-organic frameworks by introducing cobalt metal ions. The resulting NiCo-BDC hierarchical nanostructure exhibited higher oxidation states, resulting in an impressive capacitance of 1431 F g-1. Additionally, the device based on this material exhibited exceptional capacity retention over 3000 cycles.

Synthesis and capability evaluation of quinone-enriched polymer with extended π-conjugated and contorted structures for efficient energy storage

In this study, quinone-enriched polymers (PDQs) are uniquely combined with reduced graphene oxides (rGOs) for assembling organic molecular electrodes (OMEs). The PDQ polymers are synthesized via a Schiff-base reaction involving 1,5-Diaminoanthraquinone (DAAQ) and 2,4,6-Triformylphloroglucinol (Tp). PDQ's extended π-conjugation system, substantial CO groups, and contorted structures result in excellent electrochemical properties, while strong π–π interactions with rGO enhance the cycling stability. The as-prepared PDQ/rGO-0.3 delivers a specific capacitance as high as 483.6 F g−1 at 5 mV s−1, with remarkable capacitance retentions (80 % at 100 mV s−1) and an outstanding cycling stability, where 87.8 % capacity retains after 10,000 cycles at a high current density of 5 A g−1. To verify actual energy storage performance of PDQ/rGO-0.3, an aqueous asymmetric supercapacitor (ASC) is assembled by employing 2,5-dihydroxy-1,4-benzoquinone-modified reduced graphite oxide (DHBQ/rGO) as another electrode, of which redox reaction occurs in a positive potential range. The assembled ASC displays a high energy density of 28.8 Wh kg−1 at a power density of 678 W kg−1, maintaining 98 % after 10,000 cycles in 1 M H2SO4 aqueous electrolyte. To shed a light for practical use, a tandem configuration of two ASCs (PDQ/rGO-0.3//DHBQ/rGO) are demonstrated to power 46 LEDs effectively.

Facile synthesis of NiMn2S4 nanoflakes on nickel foam for high-performance aqueous asymmetric supercapacitors

Facile synthesis of NiMn2S4 nanoflakes on nickel foam for high-performance aqueous asymmetric supercapacitors