Electrode Material For Asymmetric Supercapacitors Research Articles

Polyoxometalate/α-Fe2O3/polyaniline composite: Tailored approaches for high-performance supercapacitors

The need for portable, high-performance electronics that have high power or energy density has increased significantly in recent years. In this work, a composite material was coated on stainless steel that consists of polyoxometalate (POM)/α-Fe2O3/polyaniline (PANI) as an electrode material for a symmetric supercapacitor. α-Fe2O3 was prepared using starch as a template while PANI was electrodeposited. The physical and chemical characteristics of the modified electrodes were investigated via Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and electrochemical techniques such as cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic chargedischarge (GCD) experiments. In 1 M H2SO4, the composite had a specific capacitance of 528 F/g at a current density of 0.2 A/g. In addition, the composite exhibited a high energy density of 73.4 Wh kg−1 at a high-power density of 7.14 kW kg−1 and 91.62 % capacity retention after 10 cycles. The results show that POM/α-Fe2O3/PANI is a promising composite electrode for use as a supercapacitor electrode material.

Physical and electrochemical performance of Mn-doped zinc oxide electrode material for asymmetric supercapacitor

Manganese-doped zinc oxide has emerged as a promising material for high-performance supercapacitors (SCs) due to its enhanced electrochemical properties, including improved charge storage capacity and cycling stability. Pristine Zinc oxide (ZO) and Manganese (Mn) doped (2 wt % and 4 wt %) zinc oxide (hereby labeled: ZO, 2MZO, and 4MZO) derivatives have been synthesized via an aqueous sol-gel-based co-precipitation method. The physical characterizations of synthesized samples have been performed using TGA, XRD, FESEM, and BET. The XRD has confirmed the phase pure hexagonal wurtzite structure synthesis of ZO, 2MZO, and 4MZO samples. The FE-SEM images revealed that synthesized material had shown the mixed morphology as polyhedral particles, rods, and flakes in the nano region. Mn-doped has increased specific surface by 132 % compared to bare ZO. The electrochemical characterization techniques, including CV, GCD, and EIS, have been used to access electrochemical parameters using an aqueous 4 M KOH electrolyte. A detailed CV analysis was also carried out to investigate the capacitive contribution of the material in cycling. The electrochemical characterization techniques (CV, GCD, and EIS) have been performed to access electrochemical parameters using an aqueous 4 M KOH electrolyte. The 4MZO electrode material has shown an enhancement in specific capacitance (164.28 Fg-1) compared to pristine ZO (42.83 Fg-1). The EIS study revealed that the 4MZO has the lowest internal impedance 0.30 Ω compared to 0.70 Ω, and 2.60 Ω for 2MZO and ZO, respectively.

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

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

Nickel-Copper Bimetallic Oxide Nanoparticles Prepared by Simple Coprecipitation Method as High Performance Electrode Materials for Asymmetric Supercapacitors.

Supercapacitors with transition bimetallic oxides as pseudocapacitive materials have been of wide concern for their excellent energy storage performance. In this work, a simple coprecipitation method was used to synthesize the precursor, followed by calcination to prepare Ni-Cu bimetallic oxide materials. The structure, morphology and properties of the materials prepared by different precipitating agents and different calcination temperatures of NCO-H2C2O4 precursor were investigated. The optimum precipitant was determined to be H2C2O4, and Ni-Cu nanoparticles with regular lamellar microstructure were obtained at the calcination temperature of 400 °C. The nanostructure and morphology provide a large active channel for the rapid diffusion of electrolyte ions, and the specific capacitance of NCO-H2C2O4-400 electrode material can reach 740.31 F/g Cs at 1 A/g. The investigation of charge storage mechanism shows that the contribution rate of capacitance and diffusion control is about 37.9% and 67.2%, respectively. The electrochemical test results of the asymmetric supercapacitors (ASC) constructed with NCO-H2C2O4-400 and activated carbon show that the specific capacitance, energy density, and power density of the capacitor are 52.66 F/g, 16.45 Wh/kg, and 759.51 W/kg, respectively. Even after 5000 charge/discharge cycles at 5 A/g, it can still keep 90.57% of its initial capacity. This work not only provides competitive electrode materials for energy storage devices but also provides a feasible strategy for producing complex transition metal oxide materials with high capacitance performance.

Synthesis and characterization of MoS2-COOH /Co composite as electrode material for Asymmetric supercapacitors (SCs) and devices

Transition Metal Dichalcogenide (TMD) supercapacitors have garnered significant interest due to their considerable potential. Contributing to the advancements in this field, our study focuses on the first successful synthesis of nanoparticle Co-doped MoS2-COOH using a hydrothermal approach. We examine its performance in electrochemical applications, specifically as an electrode for a supercapacitor. The MoS2-COOH/Co composite was characterized using various techniques, including X-Ray diffraction (XRD), Fourier-transform infrared spectrum (FTIR), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectroscopy, adsorption–desorption isotherm, and thermogravimetric analysis (TGA). The supercapacitive characteristics of MoS2-COOH/Co composite in a 1 M KCl electrolyte were analyzed through cyclic voltammetry (CV), continuous current charge-discharge cycling (CD), and electrochemical impedance spectroscopy (EIS). Following 3000 charge-discharge cycles, the MoS2-COOH/Co electrode, constructed on Ni foam, exhibited a unique capacitance of 2500 F g−1 with a cyclic retention of 85 % at a density of 20 mA cm−2. The synthesized material demonstrated excellent electrochemical performance for supercapacitor applications, as evidenced by Nyquist and Bode phase angle results.

Oxygen-vacancy-enriched CuMn2O4@CoAl layered double hydroxide nickel foam serving as a sophisticated electrode material for asymmetric supercapacitors

CuMn2O4, the abundant spinel in the earth, is considered a promising electrode material in the fields of energy storage and conversion, its practical application are hindered by limitations such as the insufficient energy density and poor stability of the material. Here, CuMn2O4@CoAl layered double hydroxide nickel foam (CuMn2O4@CoAl LDH NF) with abundant oxygen vacancy was constructed applied as an electrode material by simple hydrothermal method and NaBH4 reduction. The electrochemical tests validate that CuMn2O4@CoAl LDH NF soaked in NaBH4 solution stirring for 0.5 h (donated as CuMn2O4@CoAl LDH NF-0.5) shows a remarkable specific capacitance of 1437.7 F · g−1 at the current density of 1.0 A · g−1. The capacitance retention remains 86.1 % even after enduring 5000 cycles at a higher current density of 8.0 A · g−1. Furthermore, the assembled CuMn2O4@CoAl LDH NF-0.5// activated carbon (AC) supercapacitor exhibits a capacitance of 167.5 F · g−1, achieving a maximum energy density of 52.44 Wh · kg−1 and a power density of 4029.5 W · kg−1 when operated at the current density of 1.0 A · g−1. The experimental results show that the prepared material has excellent conductivity, good chemical stability, remarkable specific capacitance, and stable cycle life as a supercapacitor electrode. All these results confirm that both the construction of CuMn2O4@CoAl LDH core-shell structure and the reduction of NaBH4 can introduce abundant oxygen vacancy defects in CuMn2O4@CoAl LDH NF, which can significantly improve the electrical conductivity and accelerate the redox kinetics.

Microwave irradiation effect of La2O3-CeO2 nanocomposites as a potential electrode material for asymmetric supercapacitor

Microwave irradiation effect of La2O3-CeO2 nanocomposites as a potential electrode material for asymmetric supercapacitor

Fabrication of composite GO/NiFe2O4-MnFe2O4-CoFe2O4 anode material: Toward high performance hybrid supercapacitors.

Here, NiFe2O4, MnFe2O4, and CoFe2O4 nanoferrites are prepared by coprecipitation synthesis technique from nickel, manganese, and cobalt chloride precursors. Synthesized nanoferrites are annealed by calcination process at 800°C for 2 h. To produce a novel anode electrode material for asymmetric supercapacitors (ASCs), the composite material of GO/NiFe2O4-MnFe2O4-CoFe2O4 is fabricated. Physicochemical aspects of the synthesized nanoferrites are evaluated. X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and x-ray photoelectron spectroscopy tests are conducted, respectively. The electrochemical activities are studied by cyclic voltammetry, glavanostatic charge-discharge, and electrochemical impedance spectroscopy (EIS) in 2 M KOH as the electrolyte. In three electrode system, the novel GO/NiFe2O4-MnFe2O4-CoFe2O4 electrode displays a high specific capacity of 325 C g-1 and preserves about 99.9% of its initial specific capacity. The GO/NiFe2O4-MnFe2O4-CoFe2O4//GO ASCs device is assembled using GO/NiFe2O4-MnFe2O4-CoFe2O4, GO, and 2 M KOH solution as the positive electrode, negative electrode, and electrolyte, respectively. Significantly, the GO/NiFe2O4-MnFe2O4-CoFe2O4//GO ASCs represent an outstanding energy density of 50.5 W h kg-1 at power density of 2560 W kg-1. Through the long-term charge discharge cycling tests, this ASC device illustrates about 93.7% capacity retention after 3000 cycles. Then, the present study provides the NiFe2O4-MnFe2O4-CoFe2O4 composite nanoferrites as a novel favorable candidate for anode material. RESEARCH HIGHLIGHTS: Simple and green synthesis of magnetic NiCo2O4/NiO/rGO composite nanostructure using natural precursor. Fabricating and designing an efficient semiconductor for degradation ability. NiCo2O4/NiO/rGO nanocomposite with advanced photo elimination catalytic routine. The photocatalytic performance of NiCo2O4/NiO/rGO was surveyed for the degradation of various antibiotics below visible radiation. Efficiency was 92.9% to eliminate tetracycline. We developed a synergetic approach to prepare a novel active material composed of GO/ NiFe2O4-MnFe2O4-CoFe2O4 by a hybrid electrode material. Green synthesis method was accomplished to attain NiCo2O4/NiO/rGO nanocomposite with advanced photo elimination catalytic routine. The oxide nanobundles were prepared with a rapid and eco-friendly method. In order to investigation of the effect of natural precursor, morphology and shape of nanoproducts was compared. NiCo2O4/NiO/rGO nanobundles possess a suitable bandgap in the visible area.

β-Ni(OH)2 nanoparticles@activated sugarcane bagasse carbon nanocomposites as an advanced hybrid electrode material for asymmetric supercapacitors

β-Ni(OH)2 nanoparticles (NPs)@activated sugarcane bagasse carbon (ASBC) nanocomposites (N@ASBC NCps) with different Ni loadings were synthesized using a hydrothermal process. The products were characterized using techniques such as X-ray diffraction (XRD), field emission scanning and transmission electron microscopy (FE-SEM and TEM), Raman spectroscopy, and Fourier transform infrared spectroscopy (FT-IR). Electrochemical performance of the products was studied. Interestingly, the maximum specific capacitance of 1213.32 F/g at 1 A/g could be achieved in a 3N@ASBC NCps positive electrode. Concurrently, the ASBC negative electrode revealed a high specific capacitance of 233.34 F/g at 1 A/g. Additionally, the fabricated asymmetric supercapacitor (ASC), ASC-ASBC//3N@ASBC NCps, had a specific capacitance (Csc) of 34.03 F/g at 1 A/g with a specific energy density (Ed) and specific power density (Pd) of 9.93 Wh/kg and 181.26 W/kg, respectively. Moreover, the device could maintain 69.47% of its capacity after a 5000-cycle test.

Fabrication of porous Ni–Co LDH@rGO nanocomposites as efficient electrode materials for asymmetric supercapacitor

Fabrication of porous Ni–Co LDH@rGO nanocomposites as efficient electrode materials for asymmetric supercapacitor

Synergistic effects of Ag nanoparticles in the rGO and Co3O4 based electrode materials for asymmetric supercapacitors

A systematic investigation of the composite electrode materials is vital in fabricating supercapacitors with high specific capacitance and good stability. The present work systematically studies the synergistic effects of Ag nanoparticles (AgNPs) on the electrochemical behaviour of rGO-based supercapacitor anode and Co3O4/rGO composite cathode. The Co3O4/(Ag/rGO) composite has been fabricated by hydrothermally growing Co3O4 nanoparticles over the previously prepared Ag/rGO support in the 70:30 ratio. The electrochemical performance of fabricated electrodes was evaluated by cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) in 1 M KOH electrolyte. The Ag/rGO electrode having 15 - 20 % of AgNPs displays a specific capacitance of 553.6 F/g by CV (@10 mV/s) and 449.4 F/g by GCD (@0.35 A/g), which is 2.9 – 3.1 times higher than pristine rGO, when scanned in the range of – 1.0 V - 0.0 V (Vs. Ag/AgCl). The Co3O4/(Ag-20/rGO) composite electrode (in the ratio 70:30) possesses 244.9 F/g of specific capacitance (by GCD @3.8 A/g in the range of – 0.2 V - 0.5 V (Vs. Ag/AgCl)), which is 3.2 and 2.0 times higher than Co3O4 and Co3O4/rGO respectively. The Co3O4, Co3O4/rGO and Co3O4/(Ag/rGO) samples retained 67 % (at 3.8 A/g), 91 % (@1.4 A/g), and 82 % (@1.4 A/g) of specific capacitance after 2000 cycles. The asymmetric supercapacitor device in rGO||Co3O4/Ag/rGO configuration shows an initial specific capacitance of 438.0 F/g, energy and power densities of 38.9 Whkg‒1 and 640 Wkg‒1, respectively, at 2 A/g current density. The demonstrated boost in performance arises due to the presence of Ag nanoparticles leading to enhanced conductivity, catalyzing the pseudocapacitive reactions and preventing the graphene layers from aggregation by acting as spacers, spacers, thus making Ag/rGO and Co3O4/Ag/rGO as potential electrode materials for asymmetric supercapacitors.

Facile synthesis of Mn3O4 nanoparticles towards high performance asymmetric supercapacitors

In the present study, Mn3O4 nanostructured particles were prepared using a one-step hydrothermal method with varying different surfactants such as CTAB, PVA and EDTA, referred to as M-CTAB, M-PVA and M-EDTA, respectively. The structural properties were systematically studied using XRD, FTIR, SEM, TEM and XPS analysis. The electrochemical performance was assessed by CV, GCD and EIS measurements. The specific capacitance of the Mn3O4 electrodes was calculated using GCD at different current densities and CV at different scan rates. The specific capacitance values of the Mn3O4, M-CTAB, M-PVA and M-EDTA were 147.5, 156.5, 157.1 and 202.7 F g−1 at 5 mV s−1, 185.6, 209.5, 211.8 and 288.8 F g−1 at 0.5 A g−1. A superior capacitance retention of 99.4 % was observed for M-EDTA electrode even after 5000 continuous charge discharge cycles. An asymmetric supercapacitor (ASC) device made of M-EDTA//AC has a high energy and power densities of 36.9 Wh kg−1, 1043 W kg−1, respectively. Two ASC devices connected in series illuminated a red LED for 90 s. Thus, the M-EDTA can be regarded as promising electrode material for asymmetric supercapacitors.

Bimetallic Nanoparticles Embedded in P,N,Br‐Codoped Carbon Matrices Derived from Heterometallic‐Organophosphine Frameworks as Electrode Materials for Asymmetric Supercapacitors

AbstractAn unprecedented method has been developed to obtain heterometallic‐organophosphine frameworks (HMOPFs) through a solvent‐free, three‐component mechanochemical process. In a ball mill, mixing copper (I) bromide with zinc (II), nickel (II) or copper (II) acetates, in the presence of (PTA‐CH2‐C6H4‐p‐COOH) Br (PTA is 1,3,5‐triaza‐7‐phosphaadamantane) as an organic linker, has produced the corresponding HMOPFs based on Cu+‐Zn2+, Cu+‐Ni2+ and Cu+‐Cu2+, respectively. The pyrolysis of HMOPFs resulted in bimetallic nanoparticles of transition metal phosphide and phosphate embedded in multi‐P,N,Br‐codoped carbon matrices (Cu−M@C). Due to the utilization of an aminophosphine organic linker, this HMOPFs‐derived approach typifies an eco‐friendly synthesis of carbon confined transition metal phosphides or phosphates. It avoids the common conventional methods that involves phosphorylation using large amounts of additional P sources, which leads to an intensive release of the flammable and poisonous phosphine gas. Also, the presence of Br at the organic linker eliminates the need for using bromine vapours to obtain halogen‐doped carbon matrices. The Cu−M@C nanocomposites were tested as negative electrode materials for asymmetric supercapacitors. Electrochemical tests included cyclic voltammetry and galvanostatic charge‐discharge experiments, which revealed the Cu−Zn@C electrode with a higher potential window as compared to Cu−Ni@C and Cu−Cu@C electrodes, achieving a rate performance of 60 % and high coulombic efficiency.

Synergistic coupling of MnS/Ni3S2 and Co(OH)2 nanosheets as binder-free electrode materials for asymmetric supercapacitors with enhanced performance

The fabrication of electrode materials with a high specific capacitance is essential for the development of enhanced performance supercapacitors. A novel binder-free electrode material, composed of MnS/Ni3S2 and Co(OH)2, was synthesized on nickel foam by hydrothermal, sulfuration, and electrodeposition techniques. The MnS/Ni3S2 exhibited a unique flower-like structure, resulting in a high specific capacitance of 1780 F g−1 at 1 A/g. By optimizing the synthesis conditions through several characterization and electrochemical tests, the MnS/Ni3S2@Co(OH)2 composite was obtained, which displayed an ultrahigh specific capacitance of 2495 F g−1 at 1 A/g and a capacitance retention rate of 86.1% after 5000 cycles at 10 A/g in three-electrode system. The synergistic coupling of MnS/Ni3S2 and Co(OH)2, along with the conductive nickel foam substrate, donated towards the excellent electrochemical performance. Furthermore, the MnS/Ni3S2@Co(OH)2//AC asymmetric supercapacitor (ASC) device was constructed with MnS/Ni3S2@Co(OH)2 as positive electrode, activated carbon (AC) as negative electrode and 1 M KOH solution as electrolyte, demonstrated a high energy density of 68.6 Wh kg−1 at 750 W kg−1 and excellent cycle stability with 91.2% capacitance retention after 10,000 cycles at 15 A/g. The outstanding electrochemical properties observed in both the pre-electrodeposition and post-electrodeposition samples indicate the effectiveness of reasonable design and construction of composite as a pathway for producing electrode materials with exceptional performance.

Hydrothermally synthesized cobalt oxide embedded polymer nanocomposites as efficient electrode material for asymmetric supercapacitors

Hydrothermally synthesized cobalt oxide embedded polymer nanocomposites as efficient electrode material for asymmetric supercapacitors

A self-sacrificing template strategy: In-situ construction of bimetallic MOF-derived self-supported CuCoSe nanosheet arrays for high-performance supercapacitors

Transition metal selenides (TMSs) are viewed as a prospective high-capacity electrode material for asymmetric supercapacitors (ASCs). However, the inability to expose sufficient active sites due to the limitation of the area involved in the electrochemical reaction severely limits their inherent supercapacitive properties. Herein, a self-sacrificing template strategy is developed to prepare self-supported CuCoSe (CuCoSe@rGO-NF) nanosheet arrays by in situ construction of copper-cobalt bimetallic organic framework (CuCo-MOF) on rGO-modified nickel foam (rGO-NF) and rational design of Se2- exchange process. Nanosheet arrays with high specific surface area are considered to be ideal platforms for accelerating electrolyte penetration and exposing rich electrochemical active sites. As a result, the CuCoSe@rGO-NF electrode delivers a high specific capacitance of 1521.6 F/g at 1 A/g, good rate performance and an excellent capacitance retention of 99.5% after 6000 cycles. The assembled ASC device has a high energy density of 19.8 Wh kg−1 at 750 W kg−1 and an ideal capacitance retention of 86.2% after 6000 cycles. This proposed strategy offers a viable strategy for designing and constructing electrode materials with superior energy storage performance.

Lewis Acid Catalyzed Amide Bond Formation in Covalent Graphene-MOF Hybrids.

Covalent hybrids of graphene and metal-organic frameworks (MOFs) hold immense potential in various technologies, particularly catalysis and energy applications, due to the advantageous combination of conductivity and porosity. The formation of an amide bond between carboxylate-functionalized graphene acid (GA) and amine-functionalized UiO-66-NH2 MOF (Zr6O4(OH)4(NH2-bdc)6, with NH2-bdc2- = 2-amino-1,4-benzenedicarboxylate and UiO = Universitetet i Oslo) is a highly efficient strategy for creating such covalent hybrids. Previous experimental studies have demonstrated exceptional properties of these conductive networks, including significant surface area and functionalized hierarchical pores, showing promise as a chemiresistive CO2 sensor and electrode materials for asymmetric supercapacitors. However, the molecular-level origin of the covalent linkages between pristine MOF and GA layers remains unclear. In this study, density functional theory (DFT) calculations were conducted to elucidate the mechanism of amide bond formation between GA and UiO-66-NH2. The theoretical calculations emphasize the crucial role of zirconium within UiO-66, which acts as a catalyst in the reaction cycle. Both commonly observed hexa-coordinated and less common hepta-coordinated zirconium complexes are considered as intermediates. By gaining detailed insights into the binding interactions between graphene derivatives and MOFs, strategies for tailored syntheses of such nanocomposite materials can be developed.

NiCoP/Co9S8 nanoflowers as advanced electrode material for asymmetric supercapacitors

This work presents the synthesis of NiCoP using the Kirkendall effect and the preparation of a three-dimensional (3D) nanoflower-like structure of NiCoP/Co9S8 through sulfur-induced dissociation. The optimized electrode sample exhibited a capacity of 1252 μAh cm−2 (31.3 mAh g−1) at 1 mA cm−2 and 898 μAh cm−2 (22.5 mAh g−1) at 30 mA cm−2. The assembled NiCoP/Co9S8 electrode/active carbon (AC)-based asymmetric supercapacitor (ASC) demonstrated a capacity retention rate of 87 % after 5000 cycles at 20 mA cm−2 current density. Furthermore, the optimized NiCoP/Co9S8 composite showed a power density of 480.1 W kg−1 at an energy density of 115.1 Wh kg−1 and a power density of 4800.1 Wh kg−1 at an energy density of 66.4 W kg−1. These findings highlight the potential of the 3D NiCoP/Co9S8 nanoflower-like structure for application in asymmetric supercapacitors.

2D g-C3N4 decorated with 1D Bi2S3 nanocomposite as a high performance electrode material for asymmetric supercapacitors

Energy accumulation and storage is one of the most vital areas and necessities in today's world. The supercapacitor is seen as one of the most promising energy storage devices for upcoming generations. In this work, two dimensional (2D) g-C3N4 nanosheets decorated with one dimensional (1D) Bi2S3 nanorods by using rapid and simple hydrothermal method. The structure, functional groups, morphology and elemental analyses of synthesized materials were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDAX). In electrochemical study, pure Bi2S3 nanorods, g-C3N4 nanosheets, and Bi2S3/g-C3N4 composite electrode material were tested. In compared to pure samples, the Bi2S3/g-C3N4 composite demonstrated high specific capacitance of 631 Fg-1 at a current density of 1 Ag-1, as well as outstanding cyclic stability of 94% retained over 5000 cycles at a maximum current density in aqueous Na2SO4 electrolyte. The Bi2S3/g-C3N4 composite electrode exhibits superior electrochemical performance owing to the synergetic effect of Bi2S3 nanorods and g-C3N4 nanosheets. Also, the Bi2S3/g-C3N4 composite has been suggested as an excellent electrode material for supercapacitor applications. The fabricated Asymmetric supercapacitor device (ASC) has high specific capacitance of 80 F g−1 with 89% capacitance retention after 5000 cycle at current density of 10 A g−1. The ASC device achieved maximum energy density of 44.4 Wh kg−1 at 999 W kg−1 in operating potential range 0–2 V. Also ASC device fabricated for practical application and tested by charging 30 S and attained a self-discharging time of 3 min.

Nanoflower-like Cu2CoSnS4 grown on nickel foam as binder-free electrode material for asymmetric supercapacitors with high rate and capacitance

The self-supporting binder-free electrode material with a special porous structure and abundant electrochemical active sites is viewed as the ideal electrode material for supercapacitors. In this work, nanoflower-like Cu2CoSnS4 was first constructed on nickel foam (NF) substrate (CCTS/NF) by a one-step solvothermal method. The nanoflower-like shape increases the channels for ion transport and presents a massive quantity of active sites, which is crucial to improving electrochemical performance. What’s more, the significant synergistic effect between the ternary transition metal ions enhances the electrochemical performance as well. As a result, the CCTS/NF-3 performs a standout specific capacitance of 1690 mF cm-2 at 2 mA cm-2, a perfect rate performance of 79.6% and a superb cycle consistency of 99.6% after 5000 cycles. The assembled asymmetric supercapacitor (ASC) performs a high potential window of 0–1.4 V, a superb energy density of 0.0065 mWh cm-2 at 0.14 mW cm-2 and magnificent capacitance remains (95.6% after 5000 cycles). The electrode material has low acquisition cost and terrific electrochemical performance, and has broad utility possibilities in the supercapacitor market.