Maximum Specific Capacitance Research Articles

Controllable construction of mesoporous hollow carbon spheres rich in micropores from waterborne benzoxazine and their application in supercapacitors

Mesoporous hollow carbon spheres (MHCSs) with mesoporous channels and nanocages structure have unique advantages in energy storage. However, this structure alone does not significantly enhance the electrochemical double layer capacitance (EDLC). Additionally, the current hydrophobic nature of polymer precursors with high char yield impedes effective binding with templates due to polarity differences. Moreover, the use of toxic organic solvents presents obstacles to further development. So, it remains a challenge to prepare MHCSs rich in micropores using polar polymers with high char yield in green solvent. In this work, we prepared MHCSs rich in micropores (MMHCSs) using waterborne benzoxazine as a carbon sources and dendritic/fibrous nano-silica as a sacrificial hard template using water as the solvent and combined with freeze-drying, curing, carbonization and an activation step. The optimal MMHCSs (MMHCSs306–1–7000.5h) has a large specific surface area (1057 m2 g−1), and has a maximum specific capacitance value near 221.45 F g−1 at 0.5 A g−1 in a three-electrode system, the specific capacitance still reaches 156.66 F g−1 at a high current density (20 A g−1) due to the full utilization of micropores in the presence of mesoporous-shell and hollow-core. When assembled into a symmetrical supercapacitor, the energy density reaches 5.91 Wh kg−1 when the power density is 137.5 W kg−1. The study provides an eco-friendly method for preparing MMHCSs, and the unique structure has potential application in supercapacitors.

Optical and electrochemical analysis of nitrogen-doped carbon quantum dots from Moosa balbeesiaana peels for advanced supercapacitor applications

The demand for suitable electrode materials for energy storage devices, driven by increasing energy needs and environmental concerns, has led to the investigation of green synthesis methods. In this study, a composite material (rGO@NCQDs) comprising nitrogen-doped carbon quantum dots (NCQDs) derived from Moosa balbeesiaana peels and reduced graphene oxide (rGO) was synthesized via hydrothermal methods to evaluate its photophysical properties and electrochemical performance for supercapacitors applications. Additionally, the electrochemical behavior of rGONCQDs combined with Vanadium pentoxide (V2O5) was explored.Characterization techniques including FTIR spectroscopy revealed typical carbon-based material features in rGO-decorated NCQDs, and rGONCQDs@V2O5 composite. SEM analysis illustrated distinctive surface structures (mushroom-shaped for rGO@NCQDs and flowered-shaped for rGONCQDs@V2O5), while XRD confirmed crystalline structures with specific sizes.Photophysical investigations demonstrated significant Solvatochromic shifts and strong solute-solvent interactions in the composites. Electrochemical studies, including cyclic Voltammetry and Galvanostatic measurements, exhibited promising performance metrics. Specifically, rGO@NCQDs demonstrated a specific capacitance of 134.68 Fg−1 with excellent retention over 5000 charge-discharge cycles. In contrast, rGONCQDs@V2O5 exhibited a maximum specific capacitance of 562.62 Fg−1 at a scan rate of 10 mVs−1 and exceptional cycle stability (96 % retention over 5000 cycles).These findings highlight the potential of the synthesized composites as efficient electrode materials for supercapacitors, offering enhanced electrochemical performance and stability. The study underscores the importance of green synthesis approaches in developing functional materials for sustainable energy storage applications.

Enhancing capacitive performance of MoS2 through Fe doping: Synthesis, characterization, and electrochemical evaluation for supercapacitor applications

The capacitive performance of bare MoS2 is limited due to its poor electronic conductivity. Therefore, we tried to dope different weight percentages (2 %, 4 %, 6 %, 8 %, and 10 %) of Iron (Fe) into the MoS2 to promote more active sites to improve its energy storage capacity. Given this, we have synthesized bare MoS2 and Fe-doped MoS2 using the hydrothermal method for electrochemical charge storage application. The effect of doping was well assessed using different physicochemical tests. The electrochemical properties of the bare MoS2 and Fe-doped MoS2 were evaluated using a three-electrode setup in a 3 M KOH aqueous electrolyte. As a result, the 8 % Fe-doped MoS2 electrode material demonstrates the maximum specific capacitance (CSP) of 545 F/g @ 1 A/g with 84.8 % capacitive retention over 2000 cycles at 5 A/g. Additionally, we fabricated an asymmetric solid-state supercapacitor device, which reveals a high CSP of 74.28 F/g at 4 A/g with an energy density of 72.79 Wh/kg and a power density of 10.07 kW/kg. The results asserted that the Fe-doped MoS2 is a potential electrode material for supercapacitor application.

Self-assembly of Sr2P2O7@2D rGO nano/micro-architecture for highly durable and bendable solid-state supercapattery

Metal pyrophosphate-based materials for supercapattery have recently attracted significant research interest due to their high energy density, structural stability, and cyclability. Despite this, the low electric conductivity of such compounds severely limits the rate efficiency of supercapattery. To address this challenge, self-assembly of strontium pyrophosphate (Sr2P2O7) on 2D reduced graphene oxide (rGO) was produced (Sr2P2O7@2D rGO) with varying urea and rGO proportions employing a two-stage procedure: (i) layer-by-layer (LBL) deposition of rGO nanosheets, followed by (ii) a hydrothermal method to produce strontium pyrophosphate (SP) microflakes. The effective integration of conductive rGO with Sr2P2O7 flakes has been verified by structural and morphological investigation, which indicates that rGO nanosheets offer a large number of active sites, high electrical conductivity, and a wide surface area. However, when compared to the other electrodes, the optimized SP/rGO-3 hybrid electrode possesses battery-like properties, with an outstanding specific capacity of 205 mAh/g (738C/g) in 1 M KOH at a current density of 2 A/g and maintains 99 % durability after 10000 cycles. These outcomes imply a synergistically enhanced surface redox charge storage mechanism through the inclusion of rGO (optimal) and the influence of SP nano/microarchitecture, resulting in an extended cycle lifespan and remarkable electrochemical characteristics. Furthermore, a hybrid solid-state (HSS) supercapattery developed by employing SP/rGO-3 as the cathode and rGO as the anode (SP/rGO-3//rGO) achieved a maximum specific (areal) capacity of 189C/g (52 mAh/g, 133 mF cm−2), (areal) energy density of 42.04 Wh/kg (47.3 mWh cm−2), and a power density of 2755.6 W/kg (3.1 mW cm−2). In addition, the HSS device demonstrates remarkable long-term cyclability, retaining 96 % capacity after 10000 cycles. The present research suggests that Sr2P2O7@2D rGO composites have extraordinary electrochemical properties, highlighting their potential as nano/micro-structured electrodes for future energy storage devices.

CuMn2O4 spinel electrodes: effect of the hydrothermal treatment duration on electrochemical performance

CuMn2O4 (CMO) thin films are produced using a simple hydrothermal method. The influence of reaction duration on the electrodes’ electrochemical performance is investigated. XRD data shows improved crystal structure after 24-h reaction time, with a crystallite size of 12.17 nm. Distinct vibrational peaks associated with Cu–O and Mn–O are observed in the ATR-FTIR spectra, corroborating the spinel formation after 24 h. XPS analysis shows a compositional shift over time, starting with copper hydroxide at 12 h, evolving into a mix of copper and manganese oxides, hydroxides, and oxyhydroxides by 18 h, and achieving the desired spinel composition by 24 h. Microscopic analysis reveals CMO is arranged as small sheet structures, with 4.95 ± 2.92 µm in length after 24-h reaction. The CMO24h electrode displays a maximum specific capacitance of 1187.50 Fg−1 at a scan rate of 1 mVs−1 in 1 M Na2SO4 electrolyte. The electrochemical performance of the synthesized CMO electrodes reveals a high potential for energy storage applications.

Fabrication of Cu2O/CuO Nanowires by One-Step Thermal Oxidation of Flexible Copper Mesh for Supercapacitor Applications

This study focuses on the growth of Cu2O/CuO nanowires by one-step thermal oxidation using a flexible copper mesh at oxidation temperatures in the range of 300 to 600 °C in a controlled atmosphere of mixed-flow Ar and O2 gases. Thermal oxidation is one of the simplest used methods to obtain nanowires on a metal surface, offering advantages such as low production costs and the ability to produce metal oxides on a large scale without the use of hazardous chemical compounds. The growth of metal oxides on a conductive substrate, forming metal/oxide structures, has proven to be an effective method for enhancing charge-transfer efficiency. The as-synthesized Cu/Cu2O/CuO (Nw) electrodes were structurally and morphologically characterized using techniques such as XRD and SEM/EDX analysis to investigate the structure modification and morphologies of the materials. The supercapacitor properties of the as-developed Cu/Cu2O/CuO (Nw) electrodes were then examined using cyclic voltammetry (CV), galvanostatic charge–discharge (GCD) measurements, and electrochemical impedance spectroscopy (EIS). The CV curves show that the Cu/Cu2O/CuO (Nw) structure acts as a positive electrode, and, at a scan rate of 5 mV s −1, the highest capacitance values reached 26.158 mF cm−2 for the electrode oxidized at a temperature of 300 °C. The assessment of the flexibility of the electrodes was performed at various bending angles, including 0°, 45°, 90°, 135°, and 180°. The GCD analysis revealed a maximum specific capacitance of 21.198 mF cm−2 at a low power density of 0.5 mA cm−2 for the oxidation temperature of 300 °C. The cycle life assessment of the all of the as-obtained Cu/Cu2O/CuO (Nw) electrodes over 500 cycles was performed by GCD analysis, which confirmed their electrochemical stability.

The enhancement and impact of Se doping on the electrochemical properties of LiMn2O4 cathode material for aqueous Li-ion batteries

Spinel LiMn2O4 is a promising cathode material for lithium-ion batteries. However, due to the Jahn-Teller effect and Mn dissolution, its capacity decreases seriously in the cycle process, which hinders its wider application. In the course of our research, we discovered that a modest infusion of Se-doping is capable of significantly augmenting the oxygen vacancy within the material, improve the conductivity of the LiMn2O4 material and promotes superior battery performance. Moreover, due to Se-doped the average valence state of Mn is raised, which effectively mitigates the Jahn-Teller effect. The optimized sample exhibits high capacity, long cycle life, and superior rate capability, with an initial discharge specific capacity of 101.0 mAh·g−1 at 7 C and capacity retention of 87.3 % after 200 cycles. The maximum specific discharge capacity of the full battery during the cycle was 97.9 mAh·g−1, the capacity retention rate after 200 cycles was 78.2 %, and the maximum energy density during the cycle is 145.1 Wh·Kg−1, which was nearly twice that of the single lithium-ion battery in this paper. The effect of Se-doped on the properties of LiMn2O4 cathode materials provides a new idea for the development of high-performance spinel lithium manganese oxide cathode materials.

Fabrication of rGO-modified ternary metal chalcogenide hybrid nanocomposite(rGO/Cu2MnSnS4) for high-performance supercapacitors

Efficient supercapacitor electrodes play a crucial role in addressing energy-related challenges and contributing to solutions for the global energy crisis. Recently, Metal chalcogenide/reduced graphene oxide (rGO) composites have garnered considerable attention due to their potential as electrode materials for supercapacitor applications. This study investigates the synergistic catalytic performance achieved by integrating ternary metal-based chalcogenides (Cu2MnSnS4) with 2D carbonaceous materials, highlighting their enhanced conductivity and catalytic activity for applications in energy conversion and environmental remediation. The current study involves the synthesis of a nanocomposite comprising rGO and copper manganese tin sulphide (Cu2MnSnS4), intended for use as an electrode material in energy storage devices. The structural characterization of the rGO/Cu2MnSnS4 nanocomposite was verified through X-ray diffraction, and the morphological analysis was conducted using scanning electron microscopy (SEM). The hybrid Cu2MnSnS4/rGO electrodes have demonstrated remarkable electrochemical characteristics, notably surpassing the performance of pure Cu2MnSnS4 in an alkaline electrolyte. Specifically, the maximum specific capacitance of Cu2MnSnS4/rGO reaches 1539 F g−1 at a scan rate of 10 mV s−1, whereas pure Cu2MnSnS4/rGO achieves a maximum specific capacitance of 948 F g−1 at the same scan rate. The findings from the electrochemical performance evaluation of the electrode material suggest that incorporating into rGO into Cu2MnSnS4 can significantly boost the supercapacitor performance of the Cu2MnSnS4 electrodes. This innovative combination has notably enhanced the overall electrochemical properties of the electrode materials, establishing it as a promising candidate for use in supercapacitor devices.

Excellent electrochemical performance of N and Mn doped NiCo2O4 functional nanostructures: an effective approach for symmetric supercapacitor application

In supercapacitors (SCs), cobaltite spinel is considered as an excellent electrode material because it is abundant on earth, cost-effective, and theoretically capable of achieving high capacitance values. However, there are number of factors that prevent spinel cobaltite from achieving its maximum theoretical specific capacitance, including low electrical conductivity, insufficient active sites, and slow charge transport. For these reasons, it is necessary to simplify the structural and compositional design to overcome these limitations. An efficient solvothermal method followed by pyrolysis was successfully used to shape NiCo2O4 nanoflowers doped with N (Nitrogen) and Mn (Manganese). In addition to increasing the ion diffusion resistance and charge transfer resistance, N and Mn-doped NiCo2O4 provides an electrical conductivity system. The optimized N, Co, and Mn4 (NCoMn4) nanoflowers (4 wt% Mn-doped NiCo2O4) exhibits maximum specific capacitance of 269Fg−1 at 1Ag−1 current density with an exceptional retention of capacitance 92% after 5,000 uninterrupted cycles in the Na2SO4 media. The electrokinetic analysis of NCoMn4 further indicates that overall charge is stored predominantly through capacitance, as compared with other electrodes. It is also worth noting that the as-fabricated symmetric supercapacitor delivers the maximum energy density of 36.11 Whkg−1 at a power density of 1.04 kWkg−1 at 1 Ag−1 current density. This work opens a new path to develop hybrid electrodes for enhanced supercapacitor applications and will specify an efficient method for improving the charge transfer capability.

Harnessing synergies: Gold-polyaniline based symmetric supercapacitor for low-frequency waveform generation

Electrochemical supercapacitors, one of the storage devices, have attracted much attention owing to their high power density, fast charge-discharge and long cycle life. In this study, we present findings of a hybrid system comprised of gold and polyaniline, fabricated via an in-situ, one pot synthesis route and designed for use in symmetric supercapacitor applications. The gold-polyaniline (Au-PANI) based hybrid material was thoroughly characterized using microscopic, optical, and surface analytical techniques to gain a comprehensive understanding of the system. The electrochemical performance of Au-PANI based electrode was examined using cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS) techniques. The hybrid system exhibited maximum specific capacitance (CS) 387 F/g at the current density of 12 A/g for three electrode system. The symmetric supercapacitor exhibited a maximum specific capacity (QS) 303 mAh/g at the current density of 0.1 A/g and achieved a maximum energy density (ED) and power density (PD) of 243 mWh/kg and 619 W/kg at the current density of 0.1 A/g and 0.9 A/g, respectively. Further, the Au-PANI based symmetric device was applied to generate low-frequency waveforms.

CNT Composite β-MnO2 with Fiber Cable Shape as Cathode Materials for Aqueous Zinc-Ion Batteries.

Rechargeable aqueous zinc-ion batteries (AZIBs) have developed into one of the most attractive materials for large-scale energy storage owing to their advantages such as high energy density, low cost, and environmental friendliness. Nevertheless, the sluggish diffusion kinetics and inherent impoverished conductivity affect their practical application. Herein, the β-MnO2 composited with carbon nanotubes (CNT@M) is prepared through a simple hydrothermal approach as a high-performance cathode for AZIBs. The CNT@M electrode exhibits excellent cycling stability, in which the maximum specific discharge capacity is 259 mA h g-1 at 3 A g-1, and there is still 220 mA h g-1 after 2000 cycles. The specific capacity is obviously better than that of β-MnO2 (32 mA h g-1 after 2000 cycles). The outstanding electrochemical performance of the battery is inseparable from the structural framework of CNT and inherent high conductivity. Furthermore, CNT@M can form a complex conductive network based on CNTs to provide excellent ion diffusion and charge transfer. Therefore, the active material can maintain a long-term cycle and achieve stable capacity retention. This research provides a reasonable solution for the reliable conception of Mn-based electrodes and indicates its potential application in high-performance AZIB cathode materials.

Optimization of Water Hyacinth Stem-Based Oxygen-Functionalized Activated Carbon for Enhanced Supercapacitors.

In the current world, storing and converting energy without affecting the natural ecosystem are considered a sustainable and efficient green energy source production technology. Especially, using low-cost, environmentally friendly, and high-cycle stability activated carbon (AC) from the water hyacinth (Eichhornia crassipes) waste material for charge storage application is the current attractive strategy for renewable energy generation. In this study, preparation of AC from water hyacinth using a mixed chemical activation agent followed by activation time was optimized by the I-optimal coordinate exchange design model based on a 3-factor/3-level strategy under nine experimental runs. The optimum conditions to prepare AC were found to be potassium hydroxide (≈17 g) and potassium carbonate (≈11 g), and the carbonization time was approximately 1 h. Under these augmented conditions, the maximum specific capacitance suggested by the designed model was found to be ≈75.2 F/g. The regression coefficient (R 2 = 0.9979), adjusted (R 2 = 0.9917), predicted (R 2 = 0.8706), adequate precision (39.2795), and p-values (0.0062) proved the good correlation between actual and predicted values. The physicochemical and electrochemical properties of the final optimized AC were characterized by thermogravimetric/differential thermal analysis (TGA/DTA), X-ray diffractometry (XRD), Fourier transform infrared (FTIR), Brunauer-Emmett-Teller (BET), scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), selected area electron diffraction (SAED), and potentiostat (CV and EIS) instruments. Finally, the optimized AC electrode after 100 cycles at a current density of 2 A g-1 retains an efficiency of 71.57%, indicating the good stability and sustainability of this material.

Eco-friendly preparation of nickel cobaltite as an electrode material in sustainable energy storage devices

In this study, urchin and tremella-like NiCo2O4 was synthesised by adopting a facile hydrothermal method using green solvents (water and ethanol). Using different ratios and pure forms of green solvents has a direct impact on materials synthesised. Ethanol based NiCo2O4 (NCO-E) illustrated tremella like microspheres with a specific surface area of 260.8 m2 g−1. The electrochemical performance confirmed that the NCO-E has a maximum specific capacitance of 2271 F g−1 at a current density of 1 A g−1. Further, as-fabricated NCO-E//AC-ASC device delivers a Cs value of 96.6 F g−1 at 1 A g−1 and a cyclic stability of 99.68 % over 5000 cycles. The device exhibited a high energy density of 30.19 Wh kg−1 at a power density of 749.48 W kg−1 and a high power density of 7542.61 W kg−1 at energy density 18.43 Wh kg−1 owing to the working electrode's effective electrochemical usage and excellent ion transfer mechanism.

Nanostructured Carbon Fibres (NCF): Fabrication and Application in Supercapacitor Electrode.

A facile interconnected nanofibre electrode material derived from polybenzimidazol (PBI) was fabricated for a supercapacitor using a centrifugal spinning technique. The PBI solution in a mixture of dimethyl acetamide (DMA) and N, N-dimethylformamide (DMF) was electrospun to an interconnection of fine nanofibres. The as-prepared material was characterised by using various techniques, which include scanning electron microscopy (SEM), X-ray diffractometry (XRD), Raman, X-ray photoelectron spectroscopy (XPS), and Brunauer-Emmett-Teller (BET) among others. The specific surface area of the interconnected NCF material was noticed to be around 49 m2 g-1. Electrochemical properties of the material prepared as a single-electrode are methodically studied by adopting cyclic voltammetry, electrochemical impedance spectroscopy, and constant-current charge-discharge techniques. A maximum specific capacitance of 78.4 F g-1 was observed for the electrode at a specific current of 0.5 A g-1 in a 2.5 M KNO3 solution. The electrode could also retain 96.7% of its initial capacitance after a 5000 charge-discharge cycles at 5 A g-1. The observed capacitance and good cycling stability of the electrode are supported by its specific surface area, pore volume, and conductivity. The results obtained for this material indicate its potential as suitable candidate electrode for supercapacitor application.

Rare earth doped bimetal hydroxide/multi-walled carbon nanotubes as composite electrodes to achieve high-energy-density asymmetric supercapacitors

A novel electrode material of Ni–Co bimetallic hydroxide composite multi-wall carbon nanotubes (La–NiCo LDH/MWCNTs/NF) doped with rare earth elements was prepared on nickel foam (NF) by a one-step hydrothermal method and doped with different concentrations of La3+ ions. The introduction of La3+ ions can increase the layer spacing of LDH materials. The acidification of MWCNTs on the surface of NF can also enhance the collection effect of NF. The synergistic effect of MWCNTs and La3+ ions further improves the specific capacitance of the material. At the current density of 1 A g−1, the maximum specific capacitance of the sample with 5 % La3+ ion concentration reaches 4396.0 F g−1, and the capacitance retention is 70.31 % after 3000 cycles of a single electrode. When assembled into a device, the device obtains a high energy density of 77.86 Wh kg−1 at a power density of 800.0 W kg−1. After assembling into an asymmetric supercapacitor, it has undergone 8000 cycles of performance testing, and the capacitance ratio is only reduced by 4.9 %. It shows good electrochemical cycle performance. This work provides a new way to study the doping of rare earth elements for supercapacitor materials.

Investigating the properties of co-precipitated nickel cobalt phosphate (NiCoP) nanoparticles for energy storage applications

Nickel cobalt phosphate (NiCoP) nanoparticles were synthesized by a co-precipitation method at concentrations of 0.1 M, 0.2 M, 0.3 M, 0.4 M, and 0.5 M. Drop-casting method was utilized in depositing the nanoparticles on the substrate surface to ensure uniform distribution on the substrate surface. Various analytical techniques including XRD, SEM, EDX, Raman spectroscopy, and electrochemical measurements were employed to comprehensively understand the structural, morphological, elemental, vibrational, and electrochemical properties of the synthesized nanoparticles. Results indicate amorphous phases for all samples, with nanoflake-like morphology observed via SEM, and constituent elements confirmed through EDX analysis. Raman spectroscopy validates the composition, while electrochemical measurements demonstrate the NiCoP electrodes’ promising utility in energy storage, particularly with the 0.1 M electrode exhibiting a maximum specific capacitance of 91.2 F g−1 and stability over 3000 cycles. Overall, the findings highlight the potential applications of NiCoP nanoparticles in energy storage and electrochemical devices, providing valuable insights for researchers in the field.

Exploring the role of metal concentrations on the chemically synthesized Ni-MOFs nanostructures for asymmetric supercapacitor

The tunable porosity and surface chemistry of metal-organic frameworks (MOFs) have made such attractive candidates for application in supercapacitors (SCs). In this article, Ni-MOFs are synthesized via the solvothermal method, employing different metal concentrations, including 1M (NM-1), 2 M (NM-2), 3 M (NM-3), and 4 M (NM-4) respectively. This article primarily focuses on the impact of different metal concentrations of Ni-MOFs on examining structural, morphological, compositional, and electrochemical performance. The structural analysis of the NM-2, NM-3, and NM-4 samples confirms the formation of Layer Double Hydroxides (LDH). The electrochemical performance is facilitated by the availability of active sites with large surface areas and favorable pore sizes that are provided by the sheet-like structure (Ni (OH)2-LDH), as revealed by morphological examination. Furthermore, supercapacitive properties in an aqueous electrolyte have been used to analyze the electrochemical characteristics of the Ni-MOF electrodes. Maximum specific capacitance (Cs) of 1668 F g−1 and specific capacity (Csp) of 294 mAh g−1 at 10 A g−1 were achieved by the NM-3 electrode. It also demonstrated a high energy density (ED) of 37.07 Wh kg−1, power density (PD) of 434 W kg−1, and remarkable retentivity of 79 % after 10,000th cycles at 100 mV s−1. From the perspective of industrial production, an asymmetric NM-3//activated carbon (AC) device was fabricated. It exhibits improved PD of 193 W kg−1 with ED of 7.32 Wh kg−1 at 3 A g−1 and an elevated Cs of 180 F g−1 at 5 mV s−1, along with a notable retention rate of 86 % even after 5000th cycles at 100 mV s−1. This study demonstrates the great potential of NM-3/LDH composites for the development of superior-performance SC applications.

Molybdenum trioxide/carbon nanotubes/poly (5-carboxylindole) (MoO3/MWCNT-COOH/P5ICA) nanocomposites as an electrode material for high-performance hybrid supercapacitors

Molybdenum trioxide/carboxyl functionalized carbon multi-wall nanotubes/poly(5-carboxylindole) (MoO3/MWCNT-COOH/P5ICA) ternary composites were prepared as supercapacitor electrodes by hydrothermal and electrochemical polymerization methods. When three materials are composite used as electrodes for supercapacitors, the advantages of each material can be effectively integrated, resulting in low impedance and high capacitance characteristics. After optimizing the electrochemical polymerization time of P5ICA, the maximum specific capacitance of the composite electrode can reach 165.6 mF cm−2. The symmetric supercapacitor constructed with composite electrodes demonstrates a maximum specific capacitance of 61.0 mF cm−2, and the area specific capacitance can remain 74 % of the original after 1000 charge and discharge cycles. This study provides a feasible scheme for preparing high performance supercapacitor materials.

Synthesis of Binder-Free, Low-Resistant Randomly Orientated Nanorod/Sheet ZnS-MoS2 as Electrode Materials for Portable Energy Storage Applications.

The scientific community needs to conduct research on novel electrodes for portable energy storage (PES) devices like supercapacitors (S-Cs) and lithium-ion batteries (Li-ion-Bs) to overcome energy crises, especially in rural areas where no electrical poles are available. Herein, the nanostructured MoS2 and ZnS-MoS2 E-Ms consisting of nanoparticles/rods/sheets (N-Ps-Rs-Ss) are deposited on hierarchical nickel foam by a homemade chemical vapor deposition (H-M CVD) route. The X-ray diffraction patterns confirm the formation of polycrystalline films growing along various orientations, whereas the field-emission scanning electron microscope analysis confirms the formation of N-Ps-Rs-Ss. The change in structural and microstructural parameters indicates the existence of defects improving the energy storage ability of the deposited ZnS-MoS2@Ni-F electrodes. The specific capacitances of MoS2@Ni-F and ZnS-MoS2@Ni-F electrodes are found to be 1763 and 3565 F/g at 0.5 mV/s and 1451 and 3032 F/g at 1 A/g, respectively. The growing behavior of impedance graphs indicates their capacitive nature; however, the shifting of impedance curves toward y-axis indicates that the increasing diffusion rates due to the formation of nanostructures of ZnS-MoS2 results in low impedance. An excellent energy storage performance, minimum capacity fading, and improved electrical conductivity of the deposited E-Ms are due to the combined contributions of the electrical double layer and pseudocapacitor nature, which is again confirmed by theoretical Dunn's model. The absence of charge transfer resistance and good capacitance retention (95%) even after 10,000 cycles indicates that the deposited E-Ms are better for PES devices like S-Cs and Li-ion-Bs than MoS2 E-Ms. The assembled asymmetric supercapacitor device exhibited the maximum specific capacitance = 996 F/g, energy density = 354-285 W h/kg, power density = 2400-24,000 W/kg, capacitance retention = 95% and Coulombic efficiency = 100% even after a long charging-discharging of 10,000 cycles.

Surface active sites enriched CoNiFe-Manganite: An effective electrode for high-performance supercapacitors

The electrochemical performance of ternary metal oxide electrodes exhibiting faradic battery-type characteristics, represents a promising and desirable solution for addressing the ongoing energy crisis. In the current investigation, we present the optimized solution-combustion synthesis of Co0.03Ni0.97FeγMn2-γO4 nanoparticles, with varying Fe concentrations (γ=0.01, 0.05, 0.10 %), specifically tailored for application in supercapacitors. The Styrofoam-natured (CNMFO:1) exhibited outstanding specific capacitance, reaching 489.12 Fg−1 at a scan rate of 50 mVs−1. Moreover, validation through galvanostatic charge-discharge (GCD) investigations substantiated a notable specific capacitance of 391.41 Fg−1, achieved at a current density of 1Ag−1. In addition, the CNMFO:1 electrode demonstrated remarkable cyclic stability, retaining 83.87 % of its initial performance over 6000 cycles. Similarly, the fabricated asymmetric device of (CNMFO:1||AC) also demonstrated a maximum specific capacitance of 33.86 Fg−1 under a current density of 1Ag−1, which exhibits good energy and power density of 10.52 Wh Kg−1 and 749.34 W Kg−1 respectively. From the overall observation, the CNMFO:1 electrode exhibited notable cyclic stability and electrochemical reversibility. This research recommends that CNMFO:1 nanocomposite have an extraordinary potential for evolution of active electrode materials forthcoming supercapacitors in energy storage system.