High-performance Supercapacitors Research Articles

Rational Design of Nanosheet Array-Like Layered-Double-Hydroxide-Derived NiCo2O4 In Situ Grown on Reduced-Graphene-Oxide-Coated Nickel Foam for High-Performance Solid-State Supercapacitors.

The investigation of high-performance supercapacitors is essential for accelerating the development of energy storage devices. In this work, a 3D hierarchical nanosheet array-like nickel cobaltite/reduced graphene oxide/nickel foam composite (NiCo2O4/rGO/NF) was assembled via an aqueous coprecipitation-hydrothermal strategy assisted by citric acid. Benefiting from a NiCo layered-double-hydroxide precursor with an atomic-level lattice confinement effect of metal ions and effective hybridization with rGO, the NiCo2O4/rGO/NF composite is featured as thin NiCo2O4 nanosheets (∼113.6 nm × 11.2 nm) composed of NiCo2O4 nanoparticles (∼10.9 nm) vertically staggered on the surface of a rGO-modified NF skeleton, leading to high surface area, abundant mesoporous structure, and active site exposure. The as-obtained NiCo2O4/rGO/NF was directly used as a binder-free integrated electrode for supercapacitors, achieving an excellent specific capacitance of 2863.4 F g-1 (1503.3 C g-1) at 1 A g-1, a superior rate performance of 2335.2 F g-1 at 20 A g-1, and a stability retention of 91.7% after 5000 cycles. More impressively, a solid-state asymmetric supercapacitor assembled by the present NiCo2O4/rGO/NF integrated electrode as the positive electrode and commercial activated carbon as the negative electrode achieved a high energy density of 69.2 Wh kg-1 at a power density of 800 W kg-1, and the energy density at a peak power density of 20004 W kg-1 still remained at 48.9 Wh kg-1, also showing a good cycling stability of 87.2% retention over 10000 cycles. The present facile synthesis strategy of the as-obtained NiCo2O4/rGO/NF nanosheet array composite can be used for the design and construction of many other transition-metal oxide/graphene/NF composite materials with excellent structural stability and performance in energy storage and other related areas.

Fabrication of nickel foam/MXene/CoAl-layered double hydroxide by electrodeposition as electrode material for high-performance asymmetric supercapacitor

Layered double hydroxides (LDH) have become one of the highly promising electrode materials due to large specific area, excellent cycling stability and high energy density. However, the large internal resistance limits their applications in energy storage. The introduction of highly conductive materials is expected to solve this problem. In here, nickel foam (NF)/MXene/CoAl-LDH is prepared by electrodepositing CoAl-LDH on the surface of MXene-coated NF, and the effects of Co:Al ratio on the electrochemical properties are investigated in detail. The best electrochemical performance of the composite is obtained when Co:Al=2:1, with a specific capacitance of 646.7 F g−1 at 0.5 A g−1 and 450.8 F g−1 at 5 A g−1. Furthermore, the asymmetric supercapacitor is assembled with NF/MXene/CoAl-LDH as the positive electrode and activated carbon (AC) as the negative electrode. The voltage window of the device can reach 1.6 V. The specific capacitance of the device is 126.87 F g−1 at a current density of 0.5 A g−1. At the power density of 400 W kg−1, the energy density of 45.11 Wh kg−1 is provided. Even at the high power density of 4000 W kg−1, the energy density can still reach 17.88 Wh kg−1. After 5000 cycles at a current density of 5 A g−1, it still maintains a capacity retention rate of 92.9%. The asymmetric device with its high specific capacitance, long term stability and good power density and energy density has a great potential in energy storage applications.

Binder free cobalt Manganese layered double hydroxide anode conjugated with bioderived rGO cathode for sustainable, high-performance asymmetric supercapacitors

Metal-organic frameworks (MOFs) possessmultifunctional characteristicssuch as tuneable pore structure and high specific surface area and are being designed with great interest to enhance the electrochemical properties of current energy storage devices. In this aspect, MOFs-derived layered double hydroxides (LDHs) are important candidates for advanced supercapacitors due to their high electrochemical activity and electric conductivity. Herein, we report synthesis of Cobalt Manganese layered double hydroxides (CoMn LDH) utilising Co MOF as a precursor via ion exchange method, while optimising the dosage of Mn to achieve the best possible structural outcome. The unique structure of CoMn LDH expressed high electrochemical parameters possessing specific capacitance of 1305F/g at 1 A/g. Afterwards, an asymmetric supercapacitor device was fabricated employing CoMn LDH as cathode and coffee grounds derived rGO (reduced graphene oxide) as anode. The as-prepared asymmetric supercapacitor device demonstrated a maximum working potential window of 1.2 V with energy and power density of 23.8 Wh/kg and 0.30 kW/Kg respectively. The device also exhibits superiorcoulombic efficiency and capacitance retention of 71.11 % and 82.7 % respectively over 3010 charge–discharge cycles that represents an effectiveapproach towards sustainable and effectiveenergy storage devices. In a nutshell, our study centred on adjusting composition, engineering structures, and assembling devices.

NiCo2O4@SnS2 nanosheets on carbon cloth as efficient bi-functional material for high performance supercapacitor and sensor applications

Bi-functional materials provide an opportunity for the development of high-performance devices. Up till now, bi-functional performance of NiCo2O4@SnS2 nanosheets is rarely investigated. In this work, NiCo2O4@SnS2 nanosheets were synthesized on carbon cloth by utilizing a simple hydrothermal technique. The developed electrode (NiCo2O4@SnS2/CC) was investigated for the detection of L-Cysteine and supercapacitors applications. As a non-enzymatic sensor, the electrode proved to be highly sensitive for the detection of L-cysteine. The electrode exhibits a reproducible sensitivity of 4645.82 μA mM−1 cm−2 in a wide linear range from 0.5 to 5 mM with a low limit of detection (0.005 μM). Moreover, the electrode shows an excellent selectivity and long-time stability. The high specific surface area, enhanced kinetics, good synergy and distinct architecture of NiCo2O4@SnS2 nanosheets produce a large number of active sites with substantial energy storage potential. As a supercapacitor, the electrode exhibits improve capacitance of 655.7 F g−1 at a current density of 2 A g−1 as compare to NiCo2O4/CC (560 F g−1). Moreover, the electrode achieves 95.3% of its preliminary capacitance after 10 000 cycles at 2 A g−1. Our results show that NiCo2O4@SnS2/CC nanosheets possess binary features could be attractive electrode material for the development of non-enzymatic biosensors as well as supercapacitors.

Biomass valorization of Mangifera Indica into hierarchical carbon materials with self-doping oxygen assisted carbonization for supercapacitor applications

ABSTRACT The exploration of biocompatible energy storage media for future generations has been continuously carried out. This includes the investigations of electrode materials that are renewable, environmentally friendly, cost-effective, and rich in heteroatoms. The electrode materials undergo carbonization as a promising thermochemical process to create an active material with a porous structure of well-defined and controlled geometry. The main objective of this study is to thoroughly examine the conversion process of electrode materials derived from Mangifera Indica Seed Shells (MIS) using carbonization and activation methods for supercapacitor applications. Pyrolysis at various temperatures was carried out to determine the definitive influence of carbonization temperature on the capacitive performance of MIS active materials. The optimum carbonization temperature of 600°C significantly enhances mesoporosity, which is positively correlated to the specific surface area, hierarchical structure, and the presence of self-doping oxygen, leading to a substantial increase in capacitive behavior. In the experiment, the MIS samples were used as electrodes for supercapacitor cells, and they were found to exhibit a specific capacitance of 255 Fg−1. The goal of this study is to offer a sustainable solution by using biomass as an active material for high-performance supercapacitor cells that can be utilized in energy storage applications.

Flower like-novel nanocomposite of Mg(Ti0.99Sn0.01)O3 decorated on reduced graphene oxide (rGO) with high capacitive behavior as supercapacitor electrodes

In this study, ceramic materials of Mg(Ti0.99Sn0.01)O3 were synthesized and decorated on reduced graphene oxide, forming a nanocomposite of rGO/Mg(Ti0.99Sn0.01)O3 (rGO/MTS001). The successful synthesis results were confirmed by XRD, UV–vis analysis, FT-IR, and SEM-EDS. The MTS001 has a flower-like morphology from scanning electron microscopy (SEM) analysis, and the nanocomposites of rGO/MTS001 showed MTS001 particles decorated on the rGO’s surface. The electrochemical performance of rGO/MTS001 and MTS001 was investigated by determining the specific capacitance obtained in 1 M H2SO4 solution by cyclic voltammetry, followed by galvanostatic charge–discharge analysis using a three-electrode setup. The rGO/MTS001 achieved a specific capacitance of 361.97 F g‒1, compared to MTS001 (194.90 F g‒1). The capacitance retention of rGO/MTS001 nanocomposite also depicted excellent cyclic stability of 95.72% after 5000 cycles at a current density of 0.1 A g‒1. The result showed that the nanocomposite of ceramics with graphene materials has a potential for high-performance supercapacitor electrodes.

Hybrid and Asymmetric Supercapacitors: Achieving Balanced Stored Charge across Electrode Materials.

An electrochemical capacitor configuration extends its operational potential window by leveraging diverse charge storage mechanisms on the positive and negative electrodes. Beyond harnessing capacitive, pseudocapacitive, or Faradaic energy storage mechanisms and enhancing electrochemical performance at high rates, achieving a balance of stored charge across electrodes poses a significant challenge over a wide range of charge-discharge currents or sweep rates. Consequently, fabricating hybrid and asymmetric supercapacitors demands precise electrochemical evaluations of electrode materials and the development of a reliable methodology. This work provides an overview of fundamental aspects related to charge-storage mechanisms and electrochemical methods, aiming to discern the contribution of each process. Subsequently, the electrochemical properties, including the working potential windows, rate capability profiles, and stabilities, of various families of electrode materials are explored. It is then demonstrated, how charge balancing between electrodes falters across a broad range of charge-discharge currents or sweep rates. Finally, a methodology for achieving charge balance in hybrid and asymmetric supercapacitors is proposed, outlining multiple conditions dependent on loaded mass and charge-discharge current. Two step-by-step tutorials and model examples for applying this methodology are also provided. The proposed methodology is anticipated to stimulate continued dialogue among researchers, fostering advancements in achieving stable and high-performance supercapacitor devices.

Preparation of silk-like reduced graphene oxide/polyaniline composites using oxidant template-guided technique for supercapacitor

The large-scale utilization of supercapacitors (SCs) demands urgently for high-performance electrode materials. Herein, the silk-like reduced graphene oxide/polyaniline (rGO/PANI) composites have been prepared by oxidant template-guided technique, it is an effective method for obtaining rGO/PANI composites with respect morphologies of PANI grow on rGO nanosheets due to δ-MnO2 acts as oxidant as well as reactive template. Initially, rGO nanosheets were employed as a reducing agent and substrate for the growth of δ -MnO2; next, aniline monomers were adsorbed on the surface of δ -MnO2 within rGO/MnO2 composites, and PANI was uniformly grown on the rGO nanosheets; finally, three of rGO/PANI composites with different mass percentages of PANI (22, 34, and 68 %) were obtained due to the varying amounts of δ -MnO2 and designated as rGO/PANI-1, rGO/PANI-2, and rGO/PANI-3, respectively. The silk-like rGO/PANI-1 and rGO/PANI-2 not only outperform rGO/PANI-3 and PANI in rate performance but also cycling stability. Moreover, the silk-like rGO/PANI-1 electrode material has an extraordinarily high-rate capability, retaining 84 % (435 ∼ 364 F/g) of its initial capacitance when the current density is increased from 0.25 to 10 A/g, and 80 % of the initial capacitance is maintained after 1000 cycles at 10 A/g. As well, the assembled rGO/PANI-1 symmetric SC demonstrates high rate capability and long term cycling stability. Therefore, the silk-like rGO/PANI-1 material’s outstanding capacitive property make it a prospective candidate for high-performance SCs.

Synthesis of oxygen vacancy-engineered Fe2O3 nanospheres on three-dimensional reduced graphene oxide for ultra-energy density performance of asymmetric supercapacitors

The synthesis of oxygen vacancy (VO) -engineered Fe2O3 (Fe2O3-x) nanospheres on three-dimensional reduced graphene oxide (3D rGO/Fe2O3-x) is proposed via a gentle and high-efficiency hydrothermal approach under reducing conditions for a high-performance asymmetric supercapacitors. The smooth and rounded 3D rGO/Fe2O3-x hydrogel appears to be intact, which possesses extremely light weight and excellent strength. The micromorphology of 3D rGO/Fe2O3-x presents a 3D interconnected macroporous network structure, and the Fe2O3-x nanospheres are distributed on the surface of 3D rGO. The specific capacity of the 3D rGO/Fe2O3-x is up to 273.2 mAh/g. An asymmetric supercapacitor 3D rGO/Fe2O3-x||3D rGO exhibits an ultrahigh energy density of 114 Wh/kg at a power density of 140 W/kg. Over 20000 cycles, the capacitance retention fading and the coulombic efficiency are 6.18% and ∼100%, respectively. Outstanding supercapacitor performances of the 3D rGO/Fe2O3-x||3D rGO are attributed to the formation of the VOs in Fe2O3 crystal structure and the distribution of Fe2O3-x nanospheres on the 3D rGO. The 3D rGO/Fe2O3-x displays great potential for utilization as high-performance supercapacitors.

Hydrothermal synthesis of nickel vanadate (Ni2V2O7) microspheres as a catalyst for high-performance supercapacitor and water-splitting applications

In this work, the hydrothermal method was employed to synthesize the nickel vanadate microspheres (NVO MSs), an effective catalyst for supercapacitor and water-splitting applications. Specifically, X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, and Brunauer-Emmett-Teller (BET) were used to examine the crystal structure, surface morphology, functional group identification, the stretching-bending vibration of the N–V–O group, and the specific surface area respectively. Additionally, this paper reports the electrochemical aspects of NVO MSs in various concentrations of KOH electrolyte using nickel foam (NF) as a current collector. As a result, the NVO-NF 1 electrode exhibited excellent electrochemical activity with a higher specific capacitance (Cs) and capacity (Csp) of 959 F/g and 119 mAh/g at a current density of 5 mA/g respectively. Moreover, the NVO-NF 1 electrode delivers maximum energy (Ed) and power density (Pd) of 26 Wh/kg and 1100 W/kg and excellent stability with 90 % retention after 4000 CV cycles. In the asymmetric liquid state device (ASC), the NVO-NF acts as a cathode, and activated carbon (AC) as a anode materials respectively. Furthermore, the fabricated ASC device reveals maximum Ed and Pd of 47 Wh/kg and 2300 W/kg at 5 mA/g and also demonstrated superior stability over 5000 cycles. Furthermore, the significant finding of the NVO-NF 1 electrodes reveals superior electrocatalytic activities such as the lowest value of overpotential (234 mV), with the sufficient Tafel slope (73 mV/dec), as well as the maximum electrochemical active surface area (670.5 cm2) in 1 M KOH at 10 mA/cm2 respectively. As a result, better performance of the NVO-based MSs in 1 M KOH electrolyte was effectively applied to power effective electrodes for energy storage and water-splitting.

Nilgiri tree peels-derived activated porous carbon for high performance supercapacitor applications

In this study, the activated porous carbon (APC-x) was collected from Nilgiri tree peels, making it a sustainable and cost-effective green synthesis approach. The raw material undergoes carbonization and activating it using KOH as chemical activation agent. The chemical composition, crystallinity and morphology of the surface of ACP-x was examined by Fourier Transform infra-red (FTIR), X-ray diffraction and Field emission scanning electron microscope (FESEM). The cyclic voltammetry technique was used to measure the electrochemical performance of APC-x using PVA/KOH gel electrolyte in two-electrode system. The highest specific capacitance value 140 F/g was obtained for APC-0 at scan rate of 10 mV/s. The use of Nilgiri tree peels as precursor for activated porous carbon production presents a sustainable approach for developing high-performance supercapacitor materials.

Facile synthesis of hybrid electrode by bimetallic MOFs/polyaniline composite for high-performance asymmetric supercapacitors

Facile synthesis of hybrid electrode by bimetallic MOFs/polyaniline composite for high-performance asymmetric supercapacitors

3D Nanoflower-like and core-shell structured heterogeneous CuCo2O4@CuCo2S4@Ni(OH)2 electrode materials for high-performance asymmetric supercapacitor

The planning and synthesis of nanocomposite materials with reasonable core-shell heterostructure are of great significance in enhancing the energy density, structural stability as well as long cycle life of asymmetric supercapacitors. We have successfully prepared CuCo2O4@CuCo2S4@Ni(OH)2 core-shell 3D nanoflower array electrode material, resulting in outstanding performance of the assembled supercapacitor. Firstly, CuCo2O4 (CuC) nanowires are grown directly on nickel foam (NF) through hydrothermal and calcination reactions, followed by the formation of heterogeneous CuCo2O4@CuCo2S4 (CuC@CuS) nanoflowers via a hydrothermal reaction by using Na2S·9H2O as a vulcanizing agent. Finally, CuCo2O4@CuCo2S4@Ni(OH)2 electrode material is obtained via the electrodeposition method under a constant voltage. The prepared electrode material is composed of conductive CuC@CuS nanoflowers as the core and deposited Ni(OH)2 nanosheets as the shell, which effectively promotes ion diffusion, increases the reactive area and thereby enhances the electrochemical performance. Impressively, the composite electrode CuC@CuS@Ni(OH)2/NF material achieves an exciting high capacitance of 3753.6 F g−1 (1 A g−1), and the cycle stability is reduced by only 7.1 % after 10,000 cycle tests in the standard three-electrode system. Furthermore, the asymmetric supercapacitor (ASC) device composed of activated carbon (AC) and CuC@CuS@Ni(OH)2 exhibits 729.75 W kg−1 power density under 59.11 Wh kg−1 energy density. The aforementioned findings demonstrate that the CuC@CuS@Ni(OH)2 nanoflower array is a very potential energy storage material.

Synthesis, analysis, and characterization of NiCo layered double hydroxide nanosheets on hollow biomass carbon for high-performance supercapacitors

Synthesis, analysis, and characterization of NiCo layered double hydroxide nanosheets on hollow biomass carbon for high-performance supercapacitors

Effect of fluoride (CoF2) based electrode material for high energy and power density asymmetric flexible supercapacitors

Herein, an asymmetric supercapacitor (ASC) device was assembled by employing the pristine CoF2 as active positive electrode material and activated carbon (AC) as negative electrode material. The CoF2 electrode exhibited an outstanding electrochemical behavior with enhanced specific capacitance (Cs) of 872 F/g at 1 A/g current density in three electrode configurations. The reversible Faradaic redox reactions in CoF2 instigate the formation of cobalt-oxyfluorides and generating the mixed valence state of Co (Co2+ and Co3+) which improves its electrical conductivity and electrochemical behaviors. Furthermore, the room temperature paramagnetic nature of CoF2 increases the gradient force of ions which could possibly increase the redox reactions at the electrolyte/electrode interface. The constructed asymmetric device structure of CoF2//AC revealed a quasi-rectangular shaped cyclic voltametric curve and symmetrical semi-triangular shaped galvanostatic charge-discharge profiles, respectively, which affirms the combined electric double layer capacitance and pseudocapacitive nature by its hybrid assembly. Hence, the constructed CoF2//AC ASC demonstrated a remarkable specific capacitance of 141 F/g, energy density of 44.06 Wh.Kg−1, and power density of 422.97 W.Kg−1 at 1 A/g with the high cell voltage of 1.5 V. The CoF2//AC ASC device retained c.a. 92 % of its initial capacitance and attained over 96 % of Coulombic efficiency after 2000 cycles of charge-discharge profiles at 1 A/g, which suggests the high electrochemical stability. This admirable electrochemical performance and the origin towards the magneto-capacitance of CoF2 could pave a new way to explore next generation high-performance supercapacitors.

One-step hydrothermal synthesis of few-layered metallic phase MoS2 for high-performance supercapacitors

In recent years, molybdenum disulfide (MoS2) has gained significant attention in the scientific community. Few-layered MoS2 demonstrates unique properties and potential applications. However, the synthesis of few-layered and high-purity 1T-MoS2 is still a challenge. In this study, we successfully employed a hydrothermal method to synthesize few-layered and high-purity 1T-MoS2. The purity of the material is controlled by a combination of sodium borohydride and ethanol. Notably, the few-layered 1T-MoS2 exhibits exceptional performance as a supercapacitor, including the high specific capacitance (250.3 ​F ​g−1 at a current density of 1 ​A ​g−1) and excellent long-trem cycling stability (90.7 ​% after 5000 cycles). Meanwhile, the asymmetric device assembled by 6-FL-1T-MoS2 and active carbon on carbon cloths exhibits excellent flexibility and high energy and power density (23.1 ​μWh cm−2 at 600 ​μW ​cm−2, 55 ​μWh cm−2 at 12000 ​μW ​cm−2). This work provides valuable insights into the synthesis of few-layered and high-purity 1T-MoS2, opening up new avenues for further research and applications.

Large-Area Fabrication of Porous Graphene Networks on Carbon Fabric via Millisecond Photothermal Processing of Polyaniline for Supercapacitors.

Supercapacitors demonstrate promising potential for flexible, multi-functional energy storage devices; however, their widespread adoption is confronted by fabrication challenges. To access a combination of desirable device qualities such as flexibility, lightweight, structural stability, and enhanced electrochemical performance, carbon fiber (CF) can be utilized as a current collector, alongside graphene as an electrochemically active material. Yet achieving a cost-effective, large-scale graphene production, particularly on CF, remains challenging. Here, a rapid (<1min) photothermal approach is developed for the large-scale production of graphene directly onto CF, utilizing polyaniline (PANI) as a polymer precursor. The in situ electropolymerization of PANI on CF facilitates its rapid synthesis on large areas, followed by conversion into graphene networks, enabling the binder-free fabrication of supercapacitor devices. These devices exhibit an areal capacitance of 180mFcm-2 (at 2mAcm-2 in 1mH2SO4), an order of magnitude higher than other fabric-based devices. Moreover, the devised photothermal strategy allows for one-step preparation of supercapacitor devices on areas exceeding 100cm-2, yielding an absolute areal capacitance of 4.5F. The proportional increase in capacitance with device area facilitates scaling and indicates the commercial viability of this approach for low-cost, energy-efficient, and high-throughput production of lightweight, high-performance graphene-based multi-functional supercapacitor devices.

Zn doping induces rich oxygen vacancies in δ-MnO2 flower-like nanostructures for impressive energy density coin cell supercapacitor

In this work, Zn-doped δ-MnO2 (ZnMO) flower-like nanostructures on carbon fibers are synthesized by one-pot hydrothermal method. It is found that insertion of Zn ions induces oxygen vacancy defects, increase in active sites and conductivity of δ-MnO2 (MO) structure. These features making ZnMO structure an excellent candidate for the fabrication of electrode material for supercapacitors. It has been revealed that ZnMO@CC electrode delivered an enhanced specific capacitance of 667 F g−1 at a current density of 1 A g−1 as compared to the pristine δ-MnO2 and previously reported nanostructures. The developed asymmetric coin cell supercapacitor (ZnMO//AC) obtained a specific capacitance of 116 F g−1 at 1 A g−1 and achieved an outstanding energy density of 71.5 Wh kg−1 at a power density of 1067.1 W kg−1. Moreover, the device retains its initial capacitance of 92 % after 8000 cycles at 8 A g−1. These results suggest that ZnMO could be an emerging electrode material for the fabrication of high-performance supercapacitors for practical applications. This research hunts for new visions for the preparation of MnO2-based material by doping strategy for energy storage applications, especially supercapacitor.

Low metal content and hierarchically porous structure of “Fabaceae-Plants” derived activated carbon for high-performance supercapacitors

Plants with naturally ordered tissues and unique cell structures have become good precursors as activated carbon (AC) electrodes for supercapacitors. The various inherent plants derived ergastic substances induce numerous impurities in ACs, seriously impeding electrochemical performance. Aiming at elevating electrochemical activities, we herein, select suitable “Fabaceae-Plants” precursors via pre-leaching and carbonization-KOH activation for purer AC supercapacitor electrodes. The inherent parenchyma tissues and intrinsic low metal ion properties ensure “Fabaceae-Plants” derived ACs have large specific surface areas (SSA) (> 3000 m2 g−1) and low self-discharge rates. After ethanol reflux, most ergastic substances were removed, leading to a lower metal ion content that meets the standard procedure in Chinese GB/T 37386-2019 codes and higher mesopore volumes due to the better KOH activation effect. The mung bean sprouts-based activated carbon (AC) prepared by ethanol reflux exhibits higher capacitance (370 F g−1 at 0.5 A g−1), excellent rate performance (81.8 % from 0.5 to 50 A g−1), and an impressively low open circuit voltage attenuation rate (19.9 mV h−1). These characteristics are attributed to the synergistic effect of low metal ion impurities and higher mesopore volumes. Hence, the “Fabaceae-Plants” derived ACs are potential materials for clean energy storage and conversion systems, and the pre-leaching strategy may propose a strategy for high value-added utilization of biomass.

Simple and affordable synthesis of a binder-free nickel-zinc sulfide electrode for high-performance supercapacitors

Due to the increasing demand for renewable energy solutions, aqueous energy systems have emerged as promising and sustainable technologies. Nanostructured transition metal sulfides, renowned for their exceptional properties, are prime candidates for electrochemical supercapacitors. In this study, we present the synthesis of nickel-zinc sulfide (Ni-Zn-S) as a binder-free supercapacitor material using the affordable successive ionic layer adsorption and reaction simple technique. The active nanomaterial was directly deposited onto a 3D Ni foam current collector substrate, negating the need for a binder. The synergistic combination of Ni and Zn enhances the electrode capacitance. Various electrochemical techniques were used to evaluate the loaded active material as a binder-free supercapacitor electrode in a 6 M KOH electrolyte. Results indicate pseudocapacitive performance, achieving a high specific capacitance of 400F/g at 0.7 A/g. This material retains 97 % of its capacity, even after 2000 cycles, showcasing exceptional long-term cycling stability. These findings underscore the potential of the Ni-Zn-S electrode for delivering low-cost, high-performance supercapacitors.