Materials For Supercapacitors Research Articles

Unveiling the Hidden Potential of Two-Dimensional Black Phosphorus for Advanced Supercapacitor Applications.

In response to the contemporary energy crisis, researchers have intensified efforts to explore green and renewable energy sources alongside developing robust energy storage devices. Supercapacitors stand out among various storage options due to their high-power density and rapid charge-discharge cycles. However, their lower energy density poses a challenge, leading to exploration of diverse electrode materials, including black phosphorus (BP). BP, with its two-dimensional (2D) layered structure akin to graphene, exhibits exceptional properties, making it a promising candidate for various applications, including energy storage. This Perspective focuses on the properties of BP as an electrode material for supercapacitors, covering electrochemical performance, charge storage mechanisms, and synthesis methods. Challenges such as restacking and stability have prompted innovative strategies to enhance BP-based supercapacitors, both qualitatively and quantitatively. Furthermore, the fabrication of BP-based hybrid nanocomposites with carbonaceous polymers, conducting polymers, and other 2D materials is discussed, highlighting their efficacy as electrode materials along with future outlooks.

Controlled synthesis and electrochemical characterization of Co3V2O8 hexagonal sheets for energy storage applications

This work explores the hydrothermal synthesis of Co3V2O8 hexagonal sheets and their effects on the structure and electrochemical properties of the electrode material, with a focus on various urea concentrations. The prepared materials were extensively characterized through a variety of imaging and electrical techniques, such as asymmetric supercapacitor studies, cyclic voltammetry (CV), Galvanostatic charge-discharge (GCD) analysis, electrochemical impedance spectroscopy (EIS), and X-ray photoelectron spectroscopy (XPS). Morphological analyses revealed that distinct hexagonal sheets formed based on the urea content. XPS analysis has provided information about the oxidation states and chemical composition of the produced materials. The high capacitance of 293 F/g with an energy density of 14.68 Wh/kg at an applied current density of 1 mA/cm2 over CVO-0.6MU sample demonstrates the electrochemical capabilities of hexagonal sheets of Co3V2O8 as electrode materials for supercapacitor, as demonstrated by electrochemistry research such as GCD, CV, and EIS. Furthermore, we were able to attain a high capacitive retention of approximately 99 % columbic efficiency up to 20,000 cycles, as well as a high power density exceeding CVO-0.6MU, or 142 W/kg. These findings showed how highly feasible our as-synthesized CVO-0.6MU electrode material is as an energy storage device. The research carried out on asymmetric supercapacitor provides more evidence of the stable and promising capacitive performance of the synthetic materials, Additionally effect of the temperature on ASC were studied. This extensive work offers crucial details regarding the electrochemical characteristics and regulated manufacture of Co3V2O8 hexagonal sheets, which may find application in future cutting-edge energy storage technologies.

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.

Conducting Polymer-Based Gel Materials: Synthesis, Morphology, Thermal Properties, and Applications in Supercapacitors.

Despite the numerous ongoing research studies in the area of conducting polymer-based electrode materials for supercapacitors, the implementation has been inadequate for commercialization. Further understanding is required for the design and synthesis of suitable materials like conducting polymer-based gels as electrode materials for supercapacitor applications. Among the polymers, conductive polymer gels (CPGs) have generated great curiosity for their use as supercapacitors, owing to their attractive qualities like integrated 3D porous nanostructures, softness features, very good conductivity, greater pseudo capacitance, and environmental friendliness. In this review, we describe the current progress on the synthesis of CPGs for supercapacitor applications along with their morphological behaviors and thermal properties. We clearly explain the synthesis approaches and related phenomena, including electrochemical approaches for supercapacitors, especially their potential applications as supercapacitors based on these materials. Focus is also given to the recent advances of CPG-based electrodes for supercapacitors, and the electrochemical performances of CP-based promising composites with CNT, graphene oxides, and metal oxides is discussed. This review may provide an extensive reference for forthcoming insights into CPG-based supercapacitors for large-scale applications.

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.

Enhancing electrochemical performance of graphene oxide/polyaniline composite through plasma-assisted chemical cross-linking and surface modification

The composite of graphene oxide (GO) and polyaniline (PANI) is a promising electrode material for supercapacitors. A high loading of PANI can provide large specific capacitance, but it is a pervasive challenge to reconcile long-term cycling stability and high-rate discharge. Herein, we focus on a GO/PANI composite with low PANI content (∼25 wt%), developing a stable network of GO with an even distribution of PANI. Moreover, significantly enhanced electrochemical performance is achieved by utilizing plasma technology. The specific capacitance increases by 99 % to 433 F g−1 at 1.5 A g−1 after Argon (Ar) plasma treatment. Even at 15 A g−1, a capacitance retention rate of 91 % is obtained. After 15,000 cycles, the capacitance retention rate is 93 %, surpassing most previously reported GO/PANI composite electrodes. The further assembled all-solid-state supercapacitors can deliver a high energy density of 13.6 Wh kg−1 and exceptional cycling stability. According to results of characterization, it is demonstrated that Ar plasma imparts GO/PANI better surface morphology and achieves etching, reduction of GO, and cross-linking of GO and PANI, thereby activating the electrochemical activities of GO and PANI while ensuring stability. In this regard, the synergistic effects of cross-linking, reduction, and etching, and the mechanism are theoretically illustrated by dynamic differential equations. This work presents plasma processing unique charm for designing graphene-based materials via a customized strategy, exploiting an effectual approach to drive the applications of graphene-based materials in energy storage.

Comparative electrochemical properties of MO (ZrO2, V2O5) based polyaniline nanocomposites for high-performance supercapacitor applications

Due to its distinctive qualities, such as its moderate energy density, extended service life, rapid discharge–charge rates, and superior safety, supercapacitors (SCs) are gaining more and more attention. A zirconium oxide ZrO2 (Zr) and vanadium oxide V2O5 (VO) based PANI nanocomposites, denoted as (ZrP for ZrO2/PANI, and VOP for V2O5/PANI) are fabricated using hydrothermal technique in this research work. Morphological and phase investigations validated the random particle shapes with good crystallinity and purity of the samples. The N2 sorption/desorption isotherm reveals a mesoporous feature of the electrodes and the highest BET surface area (36.5 m2/g) with large electroactive sites, which offers abundant faradaic reactions for charge storage. The I-V characteristics confirm their excellent conduction capabilities as well. When utilized as electrodes for SCs in the three-electrode setup, the VOP composite electrode attains the highest capacitance of 1372 F g−1 at a scan rate of 5 mV s−1 compared with other active electrodes. Besides that, the VOP electrodes offer superior cyclic stability, with a retention rate of 94.28% even after 7000 consecutive charge/discharge cycles. It has been discovered that the in two electrode VOP asymmetric device exhibited remarkable specific capacitance of 651.36 Fg−1 at 5 mV s−1 demonstrating a significant capacitance retention of 87.6% over 6000 cycles. The results suggest that the material could be a good contender for electrode materials in supercapacitors.

Symmetric two-electodes pseudosupercapacitor from trichalcogenide MoS3-MoO3-poly-O-amino-benzenethiol nanocomposite

A novel nanocomposite, MoS3-MoO3/poly-O-amino-benzenethiol (MoS3-MoO3/POABT), has been synthesized in a one-pot process and demonstrates promising applications as a material for a two-electrode configuration supercapacitor. This nanocomposite exhibits remarkable morphological characteristics, featuring uniform particles with an average diameter of 80 nm and a porous structure. The advantageous morphology contributes to the enhanced performance of the fabricated pseudo supercapacitor. The evaluation of the charge/discharge behavior and cyclic voltammetry curves of the redox reaction of the MoS3-MoO3/POABT nanocomposite reveals its efficacy as a supercapacitor material. The specific capacitance (CS) achieved for this fabricated supercapacitor is noteworthy at 152 F/g. Furthermore, the energy density (E) peaks at 12.6 W h kg−1 when operating at a current density of 0.2 A/g. This high energy density demonstrates the supercapacitor’s ability to store significant energy for practical use efficiently. Importantly, its stability remains strong, with an impressive 98% retention after 250 cycles, and even after 1000 cycles, it only slightly decreases to 95%. This remarkable stability over extended cycling periods underscores the durability of the materials in the supercapacitor. Such reliable performance establishes the MoS3-MoO3/POABT nanocomposite as a dependable choice for supercapacitor applications, ensuring longevity and consistent performance in diverse energy storage needs.

Ultrasonic assisted synthesis of nanoporous carbon/CeVO4 nanocomposite for supercapacitor and photocatalytic applications

Here, nanoporous carbon (NPC)/CeVO4 nanocomposite synthesized via ultrasonic assisted method for supercapacitor and tartrazine dye degradation application. Transmission electron microscope (TEM) studies confirmed the CeVO4 nanoparticles well embedded on the NPC surface in the NPC/CeVO4 nanocomposite. Spherical shaped CeVO4 nanoparticles are well incorporated on the surface of NPC therefore NPC/CeVO4 nanocomposite which possess a porous-like structure would improve the supercapacitor applications and dye degradation performance. As expected, the specific capacitance (Cs) values (555 F g−1) of NPC/CeVO4 nanocomposite showed enhanced performance as compared to CeVO4 nanoparticles (234 F g−1) at a current density of 1 A g−1 and the capacitance retention of the designed electrode as 95 % after 5000 cycles. The photodegradation of tartrazine dye using pure CeVO4 nanoparticles and NPC/CeVO4 nanocomposite was explored under visible light irradiation. The photocatalytic degradation experiment demonstrated that the NPC/CeVO4 exhibits the maximum degradation efficiency (98.76 %) of the tartrazine with was reached within 120 min. Moreover, the rate constant of NPC/CeVO4 for tartrazine dyes decomposition was 0.0192 min−1 representing that it is two-fold higher than pure CeVO4 (0.0073 min−1). The superior electrochemical and photocatalytic properties of NPC/CeVO4 nanocomposite have been observed due to the well-designed structure and high surface area. Consequently, as-prepared NPC/CeVO4 material could be a promising material for electrochemical supercapacitor and dye degradation of the tartrazine organic pollutant.

Multifunctional applications of novel copper magnesium vanadate nanoparticles: Photocatalytic dye degradation and electrochemical properties

The multifunctional applications of nanomaterials in energy saving, electrochemical energy storage, and sensing devices are a current research trend. Novel Copper Magnesium Vanadate (CMV-CuMg2V2O8) nanoparticles have been synthesized by solution combustion method. The crystallite size calculated from XRD and TEM results was found to be 21 nm. The band gap estimated from UV–Vis DRS of CMV nanoparticles was found to be 3.82 eV. Its multifunctional applications were explored through for energy conversion, storage and sensing applications. Photocatalytic degradation of Acid Red-88 (AR-88) dye was conducted using CMV nanoparticles as photocatalyst under UV light. CMV nanoparticles modified carbon paste electrodes were prepared and its cyclic voltammetry (CV), Electrochemical impedence spectroscopy (EIS) and Galvanostatic charge–discharge (GCD) analysis were carried out using 1M KCl and NaOH electrolyte. With excellent specific capacitance of 266 Fg−1 in KCl electrolyte and 242 Fg−1 in NaOH electrolyte at 5 mV/s scan rate, CMV NPs was demonstrated to be a promising electrode material for supercapacitors. Electrochemical sensing analysis was carried out using the same electrode for the detection of paracetamol and ibuprofen within the range of 1–5 mM. The resulting copper magnesium vanadate nanoparticles have been verified as a possible electrode material for next-generation energy storage devices.

Oriented growth of NiCo metal–organic framework nanosheets on electrode materials for ternary mixed metal oxide supercapacitors

Metal–organic frameworks (MOFs) are porous structures that possess high specific surface areas, making them promising cathode materials for energy storage devices. However, solving the problems of random growth and easy aggregation of MOF nanosheets remains a challenge. In this study, hydrothermal and calcination methods were used to successfully create nickel cobalt molybdenum metal oxide (NCMO) nanoflowers, followed by the directional growth of NiCo–MOF on its surface. The oriented growth of NiCo–MOF nanosheets on NCMO nanospheres effectively prevented agglomeration, forming NCMO@NiCo–MOF with enhanced electrochemical sensitivity and a large quantity of active sites. When used as an electrode, NCMO@NiCo–MOF forms a large contact area with the electrolyte, demonstrating a high specific capacitance of 1724 F g−1 at a current density of 1 A g−1. Furthermore, at a power density of 824.8 W kg−1, an asymmetric supercapacitor constructed from NCMO@NiCo–MOF and activated carbon exhibited a high energy density of 44.5 Wh kg−1. This study presents a facile method for the assembly of MOF nanosheets for three-dimensional supercapacitors.

Natural N/O/S co-doped defect-rich functional carbon materials for aqueous supercapacitors: Effect mechanism of N-containing functional groups on chemical activation

The efficient synthesis of porous carbons with a micro-mesoporous composite structure from low-cost, multi-source biomass was of significant importance for the fabrication of carbon-based supercapacitors. A novel method for the preparation of micro-mesoporous composite carbon materials by co-pyrolysis of multi-source biomass coupled with KOH activation was proposed in this study. The N, O and S co-doped micro-mesoporous composite carbon materials were synthesized using the bamboo and spiral algae as the precursors and KOH as the activator. Spiral algae, as the main source of heteroatoms, played multiple roles (pore forming agent, dopant and enhancer) in the co-pyrolysis process. The enhanced effect of heteroatom doping on KOH activation facilitated the formation of microporous structures. The KCA-500–2 exhibited a porous structure dominated by micropores, with a specific surface area (SSA) of 2421.85 m2/g. At 0.5 A/g, KCA-500–2 displayed an excellent capacitance of 460F/g and outstanding rate performance (73.5 %). The assembled aqueous symmetric supercapacitor (KCA//KCA) demonstrated a maximum energy density of 19.09 Wh/kg at a power density of 150 W/kg. In addition, KCA//KCA attained 97.96 % capacitance retention after 9,000 cycles. This work revealed the synergistic mechanism between N-containing functional groups and KOH activation, suggesting a theoretical guidance for the synthesis of high-performance supercapacitors.

NiCo layered double hydroxides/carbon dots composites with S-doing for high-performance asymmetric supercapacitors

The pursuit of high-performance electrode materials for supercapacitors has led to the exploration of transition metal layered double hydroxides (LDH), which boast an impressive theoretical specific capacitance. However, their intrinsic limitations, such as poor electronic conductivity and slow diffusion kinetics, have posed significant challenges for their practical implementation. In this work, a NiCo LDH/carbon dots (CDs) composite with S-doping has been meticulously designed to overcome the aforementioned limitations through a synergistic combination of heteroatom doping and carbon incorporation. Utilizing a one-pot hydrothermal method, the composite electrode for the application of asymmetric supercapacitors have been in-situ growth on Ni foam substrate, which not only serves as a robust support but also contributes to the formation of NiCo LDH by providing a uniform Ni source, thereby ensuring strong adhesion and structural integrity. The morphology and microstructures of composites could be finely modulated by adjusting CDs amount. With moderate CDs contents, the optimum electrode S-LDH/CDs-2 exhibits distinctive 3D needle-like spherical morphology, coupled with the ample space for ion diffusion. Consequently, the electrode demonstrates outstanding electrochemical performance, featuring a high areal capacitance of 5157 mF cm−2 at a current density of 2 mA cm−2. Additionally, it exhibits noteworthy rate performance and maintains excellent cycling stability. Integrating the innovative electrode into asymmetric supercapacitors configuration, superior energy density (0.24–0.45 mWh cm−2) and power density (4–20 mW cm−2) as well as good stability have been achieved for the S-LDH/CDs-2//AC device. These results indicate that S-doped NiCo LDH/CDs composite electrode has the desirable potential to be a candidate for energy storage devices.

Combined experimental and density functional theory approaches to address different mechanisms of nitrogen and sulfur doping on the enhancement of capacitive performance of hierarchical porous biochars

Activated carbon derived from biomass as hierarchical porous biochars (HPB) has been developed as electrode materials for supercapacitors. Nitrogen is known as the doping element that enhances quantum capacitance, but the mechanisms of sulfur doping on the quantum capacitance enhancement remain ambiguous. In this study, conventional approaches to assess the characteristics and capacitive performance of biochars were combined with density functional theory (DFT) calculations to assess different mechanisms of nitrogen and sulfur doping. The Bbiochar samples were prepared from the pyrolyzed fish bone powder at 800 °C without additional doping possessed a specific capacitance of 240 F g−1 at 1 A/g within 1 M H2SO4. Interestingly, additional nitrogen doping through urea mixing and additional sulfur doping through thiosulfate mixing prior to the pyrolysis enhanced the specific capacitance of biochar samples to exceed 400 F g−1 under the same condition. The urea mixed sample possessed low porosity but high charge transfer resistance, while the thiosulfate mixed sample possessed high porosity but low charge transfer resistance. The different underlying mechanisms were discussed through DFT calculations on graphene models designed based on the x-ray photoelectron spectroscopy (XPS) results. Nitrogen-doped configurations with topological defects mainly stored charge at the dangling atoms and possessed a relatively high quantum capacitance. Meanwhile, doped configurations of oxidized sulfur groups required relatively low formation energy and possessed large bond dipoles, corresponding to larger pore size and surface area of the thiosulfate mixed biochars. Understanding the contrary between effects of nitrogen and sulfur doping could resolve the bottleneck on enhancing the performance of electronic double layer supercapacitors.

Core-shell structured MgCo2O4@Ni(OH)2 nanorods as electrode materials for high-performance asymmetric supercapacitors

In the field of energy storage, supercapacitors have received extensive attention in recent years. However, achieving the expected electrochemical performance and energy density of supercapacitors is still a huge challenge. The design and synthesis of binder-free composite electrode with core–shell structure is an effective strategy to improve the electrochemical performance of supercapacitors. In this paper, a heterogeneous core–shell structured and binder-free electrode material MgCo2O4@Ni(OH)2 (MCO@NH) grown on nickel foam (NF) is prepared by a simple hydrothermal and oil bath method. The unique core–shell structure makes the MCO@NH have a large specific surface area, which provides abundant active sites for ion transport and storage, thereby improving the electrochemical performance. The MCO@NH/NF nanocomposite demonstrates a high specific capacitance (Cs) of 1583 F g−1 at 1 A/g. A solid-state asymmetric supercapacitor (ASC) assembled with MCO@NH/NF and active carbon (AC) exhibits excellent energy density (45 Wh kg−1 at 457.5 W kg−1) and outstanding capacitance (89.51 %) and coulombic efficiency (97.8 %) after 12,000 cycles, evidencing its good operation stability and potential practical applications. Therefore, the prepared core–shell MCO@NH/NF electrode can be a promising candidate for energy storage devices.

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.

Controllable Metal–Organic Framework‐Derived NiCo‐Layered Double Hydroxide Nanosheets on Vertical Graphene as Mott–Schottky Heterostructure for High‐Performance Hybrid Supercapacitor

Layered double hydroxide (LDH) is considered a highly promising electrode material for supercapacitors (SCs) due to its high theoretical specific capacitance. However, LDH powders often suffer from poor electrical conductivity, structure pulverization, slow charge transport, and insufficient active sites. Herein, a self‐supporting electrode with a Mott–Schottky heterostructure has been designed for high‐performance SCs. The electrode consists of low crystallinity NiCo‐LDH nanosheets and vertical graphene (VG) directly grown on carbon cloth. The LDH was converted from a metal–organic framework (MOF) by the sol–gel method. This self‐supporting electrode provides fast charge transfer, reducing the pulverization effect and energy barrier. The Mott–Schottky heterostructure of LDH@VG regulates electron density and enhances electron transfer, as confirmed by density functional theory calculation. The optimized LDH@VG heterostructure electrode exhibits an excellent areal capacitance of 5513.8 mF cm−2 and rate capability of 82.1%. Furthermore, the fabricated hybrid SC demonstrates excellent energy density of 404.8 μWh cm−2 at 1.6 mW cm−2 and a remarkable cycling life, with a capacitance of 92.0% after 10 000 cycles. This work not only provides a simple dip‐coating and MOF conversion method to synthesize heterojunction‐based electrodes, but also broadens the horizon for designing advanced electrode materials for SCs.

Cobalt-copolymer-derived Co9S8 superstructure as electrode materials for advanced symmetric supercapacitor

Transition metal sulfides are easy to agglomerate and suffer irreversible damage due to lattice distortion caused by phase transformation, which affects the structural stability of electrode materials. In order to solve the inherent defects, cobalt-copolymer precursor was successfully synthesized, and then Co9S8/CHS superstructure are prepared by in-situ carbonization method. It exhibits a hydrangea-like structure, which is composed of numerous ultrathin nanosheets. The Co9S8/CHS material shows different voltage windows as a working electrode, which can be used as both positive and negative electrodes. A symmetric supercapacitor was assembled with Co9S8/CHS electrodes, which can deliver a high energy density of 15 Wh kg−1 at 197.08 W kg−1. When the power density increases to 800.14 W kg−1, the energy density still reaches 12.38 Wh kg−1. Additionally, the specific capacitance can still maintained at 113.02 F g−1 after 2000 cycles at the current density of 1 A g−1, the capacitance retention is up to 90% relative to the initial capacitance.

A novel binary composite of CuCoNi-MOF/MoO3 with exceptional capacitance as electrode material for supercapacitors

Metal-organic framework (MOF), a new type of electrode material with a porous structure, has shown promise as a good choice for supercapacitors in the next generation of energy storage devices. These research endeavors initiated the development of a doping technique and the creation of a composite material using solvothermal synthesis. This study involves the successful synthesis of CuCo-MOF and CuCoNi-MOF by introducing Co and Ni metals into the Cu-MOF. The CuCoNi-MOF is then combined with MoO3 to form a novel binary composite known as CuCoNi-MOF/MoO3. These prepared materials are then subjected to several physiochemical and electrochemical characterization techniques. The electrochemical characteristics of the prepared samples are estimated using a three-electrode cell setup. The analysis included cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge/discharge (GCD). The examination of the CV reveals that the binary composite CuCoNi-MOF/MoO3 exhibits exceptional capacitance (937.5 Fg−1 at 5 mVs−1) in comparison to the other materials that were synthesized. Moreover, the GCD study reveals that it has a capacity of 1364.69 Fg−1 at 0.5 Ag−1. Furthermore, it retained 91.5 % of its capacity after 5000 cycles demonstrating its exceptional stability. Owing to the exceptional electrochemical properties of CuCoNi-MOF/MoO3, it is employed as the positive electrode and activated carbon (ActC) as a negative electrode for device fabrication. The supercapattery (CuCoNi-MOF/MoO3||Act-C) showed an excellent specific capacitance of 218.83 Fg−1 at 1 Ag−1 along with an outstanding energy density of 59.57 Wh.kg−1 and power density of 704.9 W.kg−1. Moreover, the assembled supercapattery device shows remarkable stability of 95.2 % at 10 Ag−1 after 15,000 cycles.

Dielectric barrier discharge low-temperature plasma modification of bamboo charcoal for supercapacitor applications

Biochar is commonly utilized as an electrode material in supercapacitors. However, the conventional carbonization process often results in macromolecular compounds, which obstruct the porous structure of carbon materials, thereby reducing their capacitance. Dielectric barrier discharge low-temperature plasma (DLTP) is a technology that transforms gases into highly excited states, utilizing high-energy particles for enhanced energy applications. This study investigated the effects of DLTP on the electrochemical performance of bamboo charcoal (BC), utilizing bamboo shavings (BS) as the carbon source. The results indicated that the specific capacitance of BC varied under different atmospheric conditions, input voltages, and treatment durations, thereby achieving a maximum increase of 144 F/g. Furthermore, when combined with KOH activation, DLTP modification further enhanced the specific capacitance of BC to 237 F/g. The DLTP treatment enhanced the specific surface area and the types of functional groups in BC, thereby leading to a significant enhancement of its electrochemical properties.