Aqueous Asymmetric Supercapacitor Research Articles

One-step electrodeposited cracked-bark-shaped NiCoMoS on carbon cloth for high-performing aqueous asymmetric supercapacitors

The present study focuses on the development of a high-performing flexible electrode with a cracked-bark-shaped nanostructure of NiCoMoS (NCMS) on carbon cloth through one-step electrodeposition. The electrode demonstrates an impressive capacitance of 10,860.0 mF cm−2 at 1 mA cm−2 and superior rate performance, maintaining a capacitance of 4212.0 mF cm−2 even at 60 mA cm−2. Cycling test reveals that the electrode retains 86.2 % of its original capacitance and nearly 100 % Coulombic efficiency after 6000 cycles at 30 mA cm−2, attributed to the effective stress release facilitated by the cracked-bark-shaped structure. An aqueous asymmetric supercapacitor, comprising of NCMS cathode, activated carbon anode and 2 M KOH electrolyte, demonstrates an energy density of 0.600 mWh cm−2 at 0.800 mW cm−2 while exhibiting superior cycling stability (82.9 % after 15,000 cycles) at 30 mA cm−2.

Zinc/lead bimetallic sulfides as hybrid material for high-performance aqueous asymmetric supercapacitor and photocatalytic degradation of organic dye

Zinc/lead bimetallic sulfides as hybrid material for high-performance aqueous asymmetric supercapacitor and photocatalytic degradation of organic dye

Synthesis and Electrochemical Performances of Fluffy Carbonized Hexagonal KCoPO4 as Pseudocapacitive Electrode for High performing Hybrid Supercapacitor Applications

AbstractElectrochemical energy storage is one of the effective ways that can address the mentioned issues as alternative energy/power produced through solar or windmills can effectively be stored for continuous usage. Hybrid/Asymmetric supercapacitors can deliver a significant amount of power density as well as increased energy density with better rate capability and longer lifespan. The fluffy carbonized hexagonal KCoPO4 synthesized via a simple sol‐gel method accompanied by calcination has delivered high capacitance and longer cyclibility as a positive electrode in aqueous asymmetric supercapacitors. The fluffy carbonized hexagonal KCoPO4 exhibited a specific capacitance equal to 725 F/g at 0.5 A/g current density with excellent cyclic stability. The predominant intercalative pseudocapacitive charge storage behavior seems to be the reason behind the high capacitance of the electrode due to the active involvement of Co2+/3+ redox couple mediate charge storage as intercalative (inner) and capacitive, (outer) surface charges storage on the electrode were close to 37 % and 63 % respectively. Aqueous Asymmetric supercapacitor mode with KCoPO4 being a positive electrode and activated carbon being a negative electrode (KCoPO4//AC) was designed to address its performance in 2 M KOH aqueous electrolyte. The fabricated device in AASc mode (AC//KCoPO4) achieved the highest energy density close to 121.1 Wh/kg with a high power density of 6945 W/kg in the potential window of 1.5 V in 2 M KOH electrolyte.

Co/Cu/C multi-doped VOx composite nanobelts for aqueous asymmetric supercapacitors

VOx, possessing multiple stable oxidation states, demonstrates high theoretical capacity, rendering it a promising candidate for supercapacitor electrodes. However, its practical capacity and cyclic performance are hindered by low electrical conductivity and sluggish diffusion kinetics. Incorporating heteroatoms into transition metal oxides has emerged as an effective approach to mitigate these challenges. Nonetheless, the reported capacities and cyclic stabilities of single-element-doped-VOx as supercapacitor electrodes remain unsatisfactory. Herein, we propose a Co/Cu/C multi-doped VOx composite (VCoCuC) nanobelts, which significantly boosts the specific capacity (5.96 C cm−2/398.6 C g−1 @ 10 mA cm−2) and cycling performance (97.1% of the initial capacity after 2,000 cycles @ 60 mA cm−2) compared to samples with only Co/Cu, Co/C, or Cu/C doping. The possible functions of each doping element are discussed. Additionally, an aqueous asymmetric supercapacitor with VCoCuC as the cathode and conductive carbon cloth (CC) as the anode is assembled to demonstrate the potential application of VCoCuC, which delivers high energy density and excellent cyclic performance. These findings highlight the potential for improving the practical capacity and cyclic performance of VOx electrodes via a multi-doping strategy.

Boron-doped diamond decorated with metal-organic framework-derived compounds for high-voltage aqueous asymmetric supercapacitors

Conductive diamond has been recognized as a promising electrode material for supercapacitors due to its excellent stability and broad electrochemical potential window. To enhance the performance of diamond-based supercapacitors, this study focuses on two key strategies: incorporating redox-active species on the electrodes and/or in the electrolytes to increase the capacitance, and constructing asymmetric supercapacitors to expand the operating voltage range. In this context, pseudocapacitive Co3O4@boron doped diamond (BDD) and Bi–Bi2O3@BDD were synthesized using metal-organic framework (MOF) decorated BDD of Co-MOF@BDD and Bi-MOF@BDD as precursor materials, respectively. An aqueous asymmetric supercapacitor was then assembled using a pseudocapacitive electrode/redox electrolyte system of Co3O4@BDD | 3.0 M KOH+0.05 M K3Fe(CN)6/K4Fe(CN)6 as the positive compartment, and Bi–Bi2O3@BDD | 3.0 M KOH as the negative compartment. The resulting device demonstrated a wide operating voltage of 1.7 V, a maximal energy density of 10.0 Wh L−1 at a power density of 333.2 W L−1. The remarkable performance can be attributed to the Faradaic redox reactions involving [Fe(CN)6]3-/4-, Co3+/Co4+, Bi0/Bi2+/Bi3+ in the electrode materials and electrolytes. This work presents a novel way for fabricating aqueous supercapacitors with high voltage, high energy and power densities, offering significant potential for various energy storage applications.

Controllable Synthesis of Manganese Organic Phosphate with Different Morphologies and Their Derivatives for Supercapacitors.

Morphological control of metal-organic frameworks (MOFs) at the micro/nanoscopic scale is critical for optimizing the electrochemical properties of them and their derivatives. In this study, manganese organic phosphate (Mn-MOP) with three distinct two-dimensional (2D) morphologies was synthesized by varying the molar ratio of Mn2+ to phenyl phosphonic acid, and one of the morphologies is a unique palm leaf shape. In addition, a series of 2D Mn-MOP derivatives were obtained by calcination in air at different temperatures. Electrochemical studies showed that 2D Mn-MOP derivative calcined at 550 °C and exhibited a superior specific capacitance of 230.9 F g-1 at 0.5 A g-1 in 3 M KOH electrolyte. The aqueous asymmetric supercapacitor and the constructed flexible solid-state device demonstrated excellent rate performance. This performance reveals the promising application of 2D Mn-MOP materials for energy storage.

Co-precipitation Synthesis and Characterization Studies of Manganese Oxide Doped with Nickel for High-Performance Energy Storage Supercapacitor Application

The advancement in nanotechnology research has facilitated the development of eco-friendly methods for the synthesis of nanoparticles. In this work, nickel (Ni)-doped manganese oxide was synthesized using the co-precipitation method. The prepared Ni-doped manganese oxide products have been characterized by X-ray powder diffraction, scanning electron microscopy (SEM), transmission electron microscope (TEM), and energy dispersive X-ray spectroscopy (EDS). The preliminary electrochemical characteristics include charge-discharge cycling, which improves the conductivity and capacitance of the high-performance aqueous asymmetrical supercapacitor. The CV analysis of the Ni-doped manganese oxide electrode demonstrated a distinctive pseudocapacitive behavior in 1 M KOH solution. The nickel (Ni) doped electrode has a higher specific capacitance value than the pure manganese oxide electrode, with a value of 2225.07 F×g-1 at a scan rate of 5 mV×s-1. Keywords: Supercapacitor, Co-precipitation method, Nanotechnology, Synthesized, Electrochemical

Oxygen evolution reaction enhancing electrochemical performance of V-doped Ni(OH)2 for aqueous asymmetric supercapacitors

Large capacitance and stable cycling performance of electrodes are critical for the success of aqueous asymmetric supercapacitors. In this study, we propose a novel synergistic strategy involving V doping and electrochemical activation to optimize the electrochemical performance of Ni(OH)2. Our results demonstrate that the oxygen evolution reaction (OER), occurring during the activation process, is crucial for performance enhancement, with V doping significantly facilitating this reaction. The optimized V-Ni(OH)2-A0 electrode exhibits a high specific capacitance of 3.9 F cm−2 at 10 mA cm−2 and excellent long-term cycling stability, retaining 88 % of its initial capacitance after 10,000 cycles at a current density of 30 mA cm−2. Furthermore, the aqueous asymmetric supercapacitor, consisting of V-Ni(OH)2-A0 and carbon cloth, achieves an energy density of 0.50 mWh cm−2 with a power density of 10.92 mW cm−2, with exceptional cyclic performance, maintaining 96 % of its capacitance after 30,000 cycles at a current density of 25 mA cm−2. These findings underscore the potential of leveraging the OER to significantly enhance the electrochemical performance of Ni(OH)2 based electrodes.

Cobalt-ions pre-intercalation MnO2 nanosheet arrays on nickel foam achieving boosted electrochemical pseudocapacitance for supercapacitors

Metal oxide have attracted much attention as a pseudocapacitive electrode for high energy density supercapacitors (SCs). However, the battery-like charge storage mechanism based on ions diffusion and valence change for metal oxide would lead to a poor cycling stability and unsatisfied rate performance. Herein, cobalt ions pre-intercalation MnO2 nanosheet arrays on Ni foam (Co-MnO2/NF) was prepared as the cathode for SCs. The capacitive behavior of MnO2 was enhanced via cobalt introduction. The optimized Co-MnO2/NF-2 demonstrated improved pseudocapacitance and stability, with a specific capacitance of 405.6 mF cm−2 at 1 mA cm−2. It retained 90.5 % of its initial capacitance at 10 mA cm−2 after 5000 cycles, which was superior to that of pristine MnO2 (222.4 mF cm−2, 65.0 % after 1000 cycles), Co-MnO2/NF-1 (295.2 mF cm−2, 85.9 % after 1000 cycles), and Co-MnO2/NF-3 (349.9 mF cm−2, 84.9 % after 1000 cycles). The asymmetric aqueous supercapacitor consisted of Co-MnO2/NF-2 and N-doped porous carbon fiber (NPCF) electrodes with an operating potential of 2.0 V reaches a high areal energy density of 0.06 mWh cm−2 at a power density of 0.5 mWh cm−2.

Fabrication of aqueous asymmetric supercapacitor device by using spinel type (FeCoNiCuZn)3O4 high entropy oxide and green carbon derived from plastic wastes

As the world shifts towards renewable energy and more efficient energy storage systems, the demand for advanced materials that can support these technologies has increased. One such promising material class is High Entropy Alloys (HEAs). Unlike conventional alloys, which are typically composed of one or two principal elements, HEAs consist of multiple principal elements in near-equiatomic proportions. Their unique atomic structure, characterized by high configurational entropy, endows them with enhanced stability, tunability, and a high specific surface area—qualities that are highly desirable in supercapacitor applications. HEAs offer significant advantages as supercapacitor electrodes, including increased energy storage capacity, superior electrochemical stability, and the potential for synergistic effects that improve overall performance such as higher energy density, longer cycle life, and greater reliability. FeCoNiCuZn)3O4 has been synthesized by utilizing multiple induction melting process in a quartz tube at 1100 °C, followed by ball milling in order to transform the small pieces into nanostructured powder. The highest specific capacitance obtained is 245.7 F g−1 at 1.5 A g−1 in three electrode measurement system. In addition, plastic biochar was prepared using pyrolysis techniques from plastic wastage. Moreover, it is utilized for supercapacitor application, which shows a maximum specific capacitance of 180 F g−1 at 1 A g−1 for three electrode system. The combing above two electrode materials, the fabricated asymmetric device shows a maximum specific capacitance of 58 F g−1 at 1 A g−1 for 3M KOH electrolyte with maximum specific energy of 23.44 Wh kg−1 at specific power of 1700 W kg−1.

N‐Doped Carbon Coated Bimetallic CoFe2O4 Nanomembranes as An Enhanced Negative Electrode for Asymmetric Supercapacitors

AbstractIn‐suit nitrogen‐doped carbon layer coated on CoFe2O4 nanomembrane (NC−CoFe2O4) directly grown on carbon cloth was successfully fabricated. The electrochemical performance was conveniently manipulated by regulating the molar ration of Co2+ : Fe3+ (molar ration=1 : 2, CoFe2O4 nanomembrane, 2.9 F cm−2). Nitrogen‐doped (N‐doped) carbon coating strategy on CoFe2O4 nanomembrane (NC−CoFe2O4) via annealing of polypyrrole (PPy) was presented and NC−CoFe2O4 nanomembranes displayed a prominent capacitance of 12.1 F cm−2 (2563.8 F g−1) at 5 mA cm−2. More important, the composite demonstrated more stable microstructure and showed long‐term cycling stability (16.0 % decrease after 7000 cycles), which was significantly better than the unmodified CoFe2O4 (55.8 % decrease after 1000 cycles). To verify the practicability of the materials, an aqueous asymmetric supercapacitor has been fabricated using NC−CoFe2O4 composite anode and MnO2/CNTs cathode, and the device has a remarkable wide operating voltage range of 1.9 V. In addition, the assembled device has an exceptional specific capacity of 1.3 F cm−2 at 10 mA cm−2, high energy density (43.3 Wh kg−1 at a power density of 642.9 W kg−1), and also with a good capacity retention rate of 84.9 % after 1000 cycles.

Calcination synthesized and self-assembled “rough bark-like” cobalt pyrophosphate for the high-performance hybrid supercapacitor as cathode materials

Transition-metal phosphate/pyrophosphate always exhibits promising theoretical electrochemical performance and has essential prospects in supercapacitors. In this study, “rough bark-like” Co2P2O7 is successfully synthesized via calcination method using ammonium cobalt phosphate as raw material. By investigating the effect of calcination temperature on the morphology of Co2P2O7, the pure cobalt pyrophosphate piece could be prepared at 600 °C (CPO-600). Due to the unique morphology and mesoporous presence, the CPO-600 exhibits a good affinity and infiltration interface with the electrolyte and displays a specific capacitance of 544 F g−1 at 1 A g−1 in 3 M KOH, which has excellent rate performance. After 10,000 cycles at 20 A g−1, it still maintains the good cycle stability with 81.48 % initial specific capacitance. Furthermore, the hybrid asymmetric aqueous supercapacitor of CPO-600//AC delivers remarkable energy densities of 10.6 Wh kg−1 at power densities of 559 W kg−1. And its gel electrolyte device also provides higher electrochemical properties and good comprehensive performance.

Synthesis of reduced graphene oxide (rGO)/polyaniline (PANI) composite electrode for energy storage: Aqueous asymmetric supercapacitor

Composite materials have gained significant interest for energy storage applications due to their possible synergistic effects. This work describes the synthesis of reduced graphene oxide (rGO)/polyaniline (PANI) composite thin films using chemical bath deposition (CBD) method. A field-emission scanning electron microscope revealed that PANI spikes coated on rGO sheets in rGO/PANI composite. The electrochemical studies of a rGO/PANI composite electrode showed a specific capacitance (Cs) of 1130F/g Cs at a scan rate of 5 mV/s in 1 M H2SO4 electrolyte. The combined effect of rGO with PANI, a aqueous asymmetric supercapacitor device (ASC) with configuration of rGO/PANI/H2SO4/WO3 produced 97F/g Cs at a 5 mV/s scan rate and retained 82 % capacitance after 5,000 galvanostatic charge–discharge cycles. The ASC achieved a high specific energy of 23 Wh kg−1 at a specific power of 732 W kg−1. The electrochemical properties of rGO/PANI composite indicate a feasible method for creating asymmetric supercapacitors.

Facile electrodeposition of CoMn2O4 nanoparticles on nickel foam as an electrode material for supercapacitors

In this study, we successfully utilized nickel foam (NF) as a scaffold for the direct deposition of ultra-thin CoMn₂O₄ (CMOs) through a one-step electrochemical deposition method. This was followed by annealing to produce a stable, free-standing electrode. This electrode was then used to develop an aqueous asymmetric supercapacitor (AASC). The optimized electrode demonstrated an exceptionally high specific capacitance of 2218.32 F g−1 at 1 A g−1 and excellent cyclic stability, retaining 86.67 % of its capacitance after 6000 cycles. An AASC device was also constructed, employing CMOs on NF as the cathode and commercially available activated carbon (AC) on carbon cloth (CC) as the anode. This configuration achieved a high energy density of 83.85 Wh kg−1 at a power density of 800.03 W kg−1, with robust cycling stability (∼87.16 % retention after 16,000 cycles at 30.0 A g−1) and nearly 100 % Coulombic efficiency. These results surpass those of many state-of-the-art supercapacitors (SCs), highlighting the significant potential for practical applications.

Photo-assisted charging of heterostructured NiCo2S4@NiCo-LDH composite electrode with remarkable photoelectronic memory effect for high-performance asymmetric supercapacitor

Rational establishment of photo-assisted supercapacitor represents a viable strategy for achieving solar energy conversion and storage. In this study, NiCo2S4@NiCo-LDH (NCS@NC-LDH) composite electrode was effectively synthesized for a highly efficient asymmetric supercapacitor (ASC). Specific capacitance of NCS@NC-LDH under light condition (3286.25 F g−1 at 1 A g−1) demonstrated notable improvement in contrast to that under dark condition (2171.5 F g−1 at 1 A g−1). Meanwhile, NCS@NC-LDH displayed strong photoelectronic memory, as a merely 3 % specific capacitance decreased when discharged under dark compared to that of continuous illumination. Additionally, the assembled aqueous ASC (NCS@NC-LDH//AC) exhibited substantial energy density (83.2 Wh kg−1 at 800 W kg−1) under light condition. Density functional theory (DFT) calculation further demonstrated that the formed matched band facilitated efficient generation-transfer of photoinduced electrons/holes and thus improved the energy storage behavior. We anticipated that this work may offer new perspectives on developing multi-component composite electrodes tailored for high-performance solar-driven electrochemical energy storage.

Controlled preparation of carbon cloth decorated with nanostructured Mn(OH)2/Mn3O4 electrodes for high-performance asymmetric supercapacitors

Environmentally friendly aqueous asymmetric supercapacitors are expected to exhibit excellent energy storage properties, stable performance, and facile production protocols. This study focused on the fabrication and characterisation of an asymmetric supercapacitor (ASC) with a commercial activated carbon (AC) negative electrode and Mn(OH)2/Mn3O4 composite on carbon cloth (hCC) positive electrode. The Mn-based electrode was synthesised using a one-step electrodeposition process. The morphology and crystalline structure of the composite electrode were modified by varying the deposition time of the Mn(OH)2/Mn3O4 nanostructures on carbon cloth substrate which greatly influence the electrochemical performance of the asymmetric systems. The best ASC used the AC electrode and a Mn(OH)2/Mn3O4@hCC electrode prepared using electrodeposition over an optimised time of 3 h. It exhibited a remarkable specific energy density of 40.7 Wh kg−1 at a power density of 100 W kg−1. In addition, this ASC demonstrated stable long-term performance, retaining 88 % of its capacitance after 5000 charge–discharge cycles, showing its great application potential in the field of supercapacitors.

Temperature driven pseudocapactive performance of WO3/MXene nanocomposite for asymmetric aqueous supercapacitors

The WO3 nanostructured materials are widely used as a pseudocapacitive charge storage electrodes. However it is restricted by poor cyclic stability. To overcome it, hybrid nanocomposites materialization of WO3 with fascinating 2D MXene is an excellent strategy. Though both materials consumes acid based electrolytes and possesses layered structures, WO3 protects MXene from self-restacking and/or aggregation of their adjacent layers owing to its strong van-der Waals interaction. Moreover layered structure of MXene offers synergistic action of various metal elements, fast diffusion of ions, increase the voltage window and cycle life. Herein we report hybrid nanocomposite of orthorhombic WO3 nanoplates with 2D MXene nanoflakes prepared by a single-step hydrothermal method. The electrochemical investigations exhibits the specific capacitances of 21 F g−1 (MXene), 112 F g−1 (WO3), and 290 F g−1 (WO3/MXene-20) at 0.5 A g−1 in 1 M H2SO4 aqueous electrolyte. Furthermore temperature dependent investigation of a hybrid nanocomposite (WO3/MXene-20) demonstrates consistent enhancement in the specific capacitance with the increasing temperature and a maximum capacitance of 376 F g−1 at 0.5 A g−1 is achieved at 50 °C. Eventually an asymmetric aqueous supercapacitor (AASC) fabricated using hybrid nanocomposite (WO3/MXene-20) demonstrates an outstanding cyclic stability up to 20,000 cycles at 5 A g−1 upholding 72 % capacitance retention and 73 % coulombic efficiency. The exceptional cyclic stability of the AASC configuration emphasizes the prospective of WO3/MXene hybrid nanocomposites for durable energy storage applications.

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.