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The green energy storage of polyaniline, without major wastages excreted into the environment is effectively demonstrated by using the polyaniline as supercapacitor electrode and the by-product obtained during the synthesis of polyaniline as its electrolyte. This green approach to the energy storage properties of sulphuric acid doped polyaniline (H-PANI) exhibited a substantial improvement in its energy storage, compared to the conventional approach of using an ionically conducting liquid as electrolyte like 1 M H2SO4 (SA), separately. The amelioration of 40.44% was achieved when the by-product obtained as supernatant liquid (SL) was used as electrolyte compared to SA. The H-PANI provided a specific capacity (Q) of 146.4 C g−1, a specific energy (E) of 24.40 W h kg−1 and a specific power (P) of 1.200 kW kg−1 at 1 A g−1 in the presence of SA. The Q of 205.6 C g−1, E of 34.26 W h kg−1 (similar range of E of Pb-acid batteries), P of 1.200 kW kg−1 were achieved in the presence of SL at 1 A g−1 and a high rate capability of 29.18% retention of initial Q up to 25 A g−1 was also achieved. This approach is useful to harvest high energy characters from PANI. [ABSTRACT FROM AUTHOR]

Supercapacitors' high power density and extended life cycle have drawn a lot of interest in energy storage devices. In this study, different nanostructures of nickel oxide (NiO) and zinc oxide (ZnO) were synthesized using the hydrothermal method by treating the corresponding metal precursors in a high-temperature aqueous solution. The XRD and SEM were used to analyse crystal structure and morphology, respectively. The absorption of ZnO and NiO materials is found to be in the visible range of 300–400 and 200–300 nm, respectively. The band gap of ZnO was calculated as 3.04 eV, while that of NiO was 3.93 eV. The supercapacitor electrode was fabricated on nickel foam with developed nanostructure and carbon materials. The composite ZnO and NiO materials showed an increase in capacitance compared to the bare NiO and ZnO electrodes. This enhancement could be related to improved charge transfer kinetics and increased surface area for electrolyte interaction. Galvanostatic charge–discharge, cyclic voltammetry and electrochemical impedance spectroscopy measurements were conducted to assess the electrochemical efficiency of nanomaterials and their composites. At the current density of 2 A g−1, the specific capacitance of the NiO/ZnO composite is found to be 351.54 F g−1, which is ~2 times of the bare NiO and ~3.34 times of bare ZnO. The maximum energy density of ZnO nanoparticles, NiO nanoflakes and the composite are found to be 3.96, 6.58 and 13.90 Wh kg-1, respectively. The charge storage process is the result of diffusion and redox reactions. This paper explores a binary oxide composites method for creating efficient supercapacitor electrode materials. [ABSTRACT FROM AUTHOR]

Here, we describe the analysis of the capacitive performance of activated carbon materials derived from the biowaste of lemon. Lemon peel discarded by restaurants after juice extraction is carbonized at 400 0C followed by chemical activation using ZnCl2. The porosity of carbon materials is tailored by varying activation conditions, such as the mass ratio of carbonized lemon peel and ZnCl2, duration of heating, and temperature. The Brunauer–Emmett– Teller (BET) surface area and pore volume of carbon materials prepared at different activating conditions range from 1380 to 2120 m2g−1 and 0.38 to 0.69 cm3 g−1 respectively. The derived carbon materials are amorphous indicated by the broad peaks in the XRD pattern as well as disordered structure of the carbon materials is revealed by the Raman spectroscopic analysis. The systematic analysis of capacitive performance of activated carbons by employing electrochemical techniques like Cyclic Voltammetry (CV), Galvanostatic charge/Discharge (GCD) cycles, and electrochemical impedance spectroscopy (EIS) in acidic (H2SO4) and alkaline (KOH) media indicates that optimum condition for activation of lemon peel is 600 °C for 60 min with 1:1 mass ratio of carbonized lemon peel and ZnCl2. The superior performance of (ALP-600) is attributed to its high surface area and well-connected hierarchical porous structure. The tiny hump at ~ 0.2 V in CV might be due to the pseudocapacitive nature of oxygen functional groups indicated by FTIR. ALP-600 exhibits the highest specific capacitance of 180 Fg−1 and retains 99.7% of its initial capacitance after 5000 cycles in the acidic electrolyte. The maximum capacitance achieved with ALP-600 symmetric cell in CR2032 coin cell configuration is 0.90F. [ABSTRACT FROM AUTHOR]

Developing supercapacitor materials that are both efficient and durable, with high cycle life and specific energy, poses a significant challenge due to issues in electrodes such as volume expansion and electrode degradation that occur over time. This work reports a simple, novel, and cost-effective synthesis method to fabricate high surface area "Iron (Fe) doped TiO2 materials" via the metal-organic framework (MOF) route for supercapacitor application. Morphological analysis revealed a disc-like shaped pattern for pristine TiO2 (PT), and a cuboid form for Fe-doped TiO2 (FeT). The electrochemical investigation of MOF-derived PT and FeT electrode materials demonstrated the superior performance of FeT. Cyclic Voltammetry revealed enhanced electrochemical properties in FeT. Galvanostatic charge-discharge measurements confirmed FeT's higher energy storage capacity, reaching a maximum specific capacitance of 925 Fg− 1. Long-term cycling tests exhibited excellent stability, with FeT retaining 67% of its initial capacitance after 6000 cycles and showing prolonged self-discharge. Overall, the results underscore the potential of Fe-doped TiO2 for high-performance supercapacitors. [ABSTRACT FROM AUTHOR]

We investigated the electrochemical performances of α-MnO2 and β-MnO2 nanorods synthesised via hydrothermal route. The electrochemical properties of α- and β-MnO2 evaluated utilising cyclic voltammetry (CV), galvanostatic charge–discharge (GCD) and electrochemical impedance spectroscopy (EIS) in 1 M KOH electrolyte revealed that the α-MnO2 electrode exhibits a specific capacity of 743 C/g whereas β-MnO2 electrode exhibited a specific capacity of 391 C/g for same current density of 3 A/g. Also, after 5000 cycles, α- MnO2 exhibits a capacity retention of 80%, while β-MnO2 shows 64% retention. The present work reports the enhanced pseudocapacitor electrode performance of α-MnO2 over β-MnO2. For practical application, synthesized α-MnO2 and activated carbon were assembled in Swagelok-type cell to fabricate hybrid supercapacitor. The hybrid supercapacitor exhibits exceptional specific capacitance of 241.25 F g−1, with excellent energy and power density of 85.77 Wh Kg−1 and 1600 W Kg−1 respectively. [ABSTRACT FROM AUTHOR]

Using discarded durian shell (DS), a waste biomass, as the raw material, DS-based activated carbon was prepared. Heteroatom doping with thiourea as the nitrogen and sulfur source was then introduced on the precursor of DS activated carbon to investigate its impact on the material's morphology and electrochemical energy storage performance as a supercapacitor electrode. Characterization techniques such as XPS, XRD, and electrochemical tests were employed to evaluate the relevant properties of the material. The results revealed that when the mass ratio of thiourea to DS activated carbon reached 2:1, the specific surface area of S-DCK-2 peaked at 2394 m2·g−1. Electrochemical testing demonstrated that S-DCK-2 exhibited a remarkable specific capacitance of 370 F·g−1 at 0.5 A·g−1, indicating its superior electrochemical performance. Subsequently, electrodes were assembled into S-DCK-2//S-DCK-2 symmetric supercapacitors in a two-electrode configuration. The results showed that the S-DCK-2//S-DCK-2 device achieved a specific capacitance of 113 F·g−1 in 6 mol·L−1 KOH at a current density of 0.5 A·g−1. The material exhibited an energy density of 15.83 Wh·kg−1 and a power density of 313 W·kg−1. The experiment confirmed that doping with sulfur and nitrogen enhanced the pseudocapacitance capacity, leading to improved electrochemical performance. [ABSTRACT FROM AUTHOR]

The rapidly expanding global population and fast economic growth has led to a shortage of energy and electricity resources. The scarcity of effective energy storage technologies and environmentally friendly electrical power alternatives is one of the greatest concerns in the modern era. Asymmetric supercapacitors have garnered considerable attention due to their versatility in energy storage devices. However, they still require more effective electrode materials with superior electrochemical characteristics to improve their charge storage capacity, energy, and power parameters. To this end, in this work, nickel oxide (NiO), lanthanum phosphate (LaPO4), and nickel oxide-decorated lanthanum phosphate (NiO/LaPO4) nanosheets were synthesized by a facile hydrothermal method. The purity, crystallinity, and morphology of the materials were investigated using x-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDS), and x-ray photoelectron spectroscopy (XPS). The NiO-decorated LaPO4 exhibited superior performance, providing higher specific capacity (Qs) of 1054.4 C/g at 2.0 A/g. The developed electrode also demonstrated excellent electrical conductivity and stability (88% galvanostatic charge/discharge [GCD] retention for 1500 cycles) as determined by electrochemical impedance spectroscopy. The capacitive and diffusive contributions indicate that the fabricated material has an asymmetric storage nature. The results suggest that the prepared material could be used in asymmetric supercapacitor applications. [ABSTRACT FROM AUTHOR]

This study presents the synthesis of CuxCo1-xFe2O4 nanoparticles as potential supercapacitor electrode materials via a sol–gel auto-combustion process. The electrochemical properties were systematically evaluated as Cu was gradually substituted with Co. Using 1 M KOH electrolyte, we characterized the electrochemical performance of CuxCo1-xFe2O4 through cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), and electrochemical impedance spectroscopy (EIS). Among the compositions, Cu0.5Co0.5Fe2O4 spinel ferrite nanoparticles demonstrated an impressive specific capacitance of 1755 F/g at a current density of 5 mA/cm2, along with a power density of 320 W/kg and an energy density of 38.40 Wh/kg. Additionally, the supercapacitor showcased remarkable cycling stability, retaining over 88.60% of its initial capacitance after 5000 GCD cycles. These findings suggest that CuxCo1-xFe2O4 is a highly promising candidate for supercapacitor applications. [ABSTRACT FROM AUTHOR]

This work describes the fabrication of a composite supercapacitor electrode made of Cu-doped BiFeO 3 (Cu-BFO) films on an activated carbon (AC) electrode using radio-frequency (RF) magnetron sputtering. To prevent exfoliation of Cu-BFO and AC upon immersion in an electrolyte, the nickel foam sandwiching electrode technique was introduced. The Cu-BFO films significantly enhanced electrochemical properties, increasing specific capacitance by up to 151% compared to that of an AC electrode. This was attributed to Faradaic reactions and specific surface area in the Cu-BFO/AC electrode. The highest specific capacitance achieved was 169 F g - 1 at 0.5 A g - 1 , and cycling stability retention was 93.12% after 500 cycles. However, the remaining percentage of the specific capacitance decreased differently with increasing thickness, which is also discussed. Furthermore, an asymmetric supercapacitor using Cu-BFO/AC and AC electrodes demonstrated a high energy density of 4.71 Wh kg - 1 , power density of 2.66 kW kg - 1 , and over 90% retention after 1000 cycles, highlighting its durability. The uniform RF magnetron sputtering deposition is vital for mass production. Combined with impressive retention in asymmetric supercapacitors, this scalability suggests a promising pathway for large-scale manufacturing. Consequently, this work could pave the way for the large-scale production of supercapacitors. [ABSTRACT FROM AUTHOR]

This study presents a simple and an environmentally friendly approach to make Laser-Induced Graphene (LIG) based supercapacitor electrodes anchored with abundant Silver Nanoparticles (AgNPs). LIG, was synthesized using a CO2 laser writing technique on polyimide substrate. The LIG-Ag composite was prepared using two techniques, drop-coating, and screen-printing. Ag nanoparticles prepared using the plant extract of Swietenia Macrophylla was utilized to drop-coat AgNP on LIG substrate. Screen-printing was done by using a commercial Ag-ink and a suitable mesh. The supercapacitor made from screen-printed electrodes and supercapacitor made form drop-coated electrodes showed a high specific capacitance of 118 mF/cm2, 38 mF/cm2, and a high energy density of 2.42 mWh/cm2, 0.05 mWh/cm2 respectively. The screen-printed composite of LIG and AgNP was further studied for its anti-fungal properties and proved to be effective against Candida sp. [ABSTRACT FROM AUTHOR]

Electrochemical energy storage devices with high specific capacity are of utmost important for the next-generation electronic devices. Supercapatteries (SCs) are highly demanded energy storage devices nowadays as these bridge the low energy supercapacitors and low power batteries. Herein, we report a rapid synthesis of cobalt manganese phosphate (COMAP) by microwave-assisted hydrothermal method and facile fabrication of SCs using electrodes comprising of COMAP as positrode material. The effect of precursor concentration on the microstructure and surface morphology of the COMAP samples are examined initially. Further, the electrochemical performance of COMAP electrodes is studied systematically in 3 M KOH (aqueous) electrolyte. COMAP exhibits excellent charge storage capabilities where type of charge storage mechanism is found to be battery-type based on the calculation obtained from Dunn's method. The SC electrode fabricated with COMAP synthesized using cobalt: manganese precursor ratio as 80:20 exhibits a highest specific capacity of 191.4 C/g at a scan rate of 1 mV/s. An asymmetric SC (ASC) cell fabricated with COMAP as positrode and activated carbon (AC) as negatrode exhibits a specific capacity of 165.5 C/g at a current density of 1.8 A/g. The COMAP//AC ASC cell exhibits an energy density of 34.1 Wh/kg at a corresponding power density of 1875 W/kg at a current density of 1.8 A/g. [ABSTRACT FROM AUTHOR]

Hybridizing batteries and supercapacitors is an innovative and promising way to meet the growing requirements of high energy and power densities in different energy storage devices. These devices have multifunctional behavior, with excellent electrochemical properties and the ability to address the limitations of conventional devices. The novel nanocomposites of NbSn-MOF@GDSs have been synthesized and studied with promising energy storage properties in the present research work. The morphological and electrochemical studies were performed for the prepared nanocomposite electrodes. The prepared material showed a great specific capacity of 423.8 mAh/g (1530.3 C/g) at a current density of 1.2 A/g with an outstanding cyclic stability of 87.1% and 81.6% capacitive retention after 5000 cycles and energy density (Ed) of 65 Wh/kg and power density (Pd) of 1400 W/kg. These findings advocated that the NbSn-MOF@GQDs-based battery hybrid supercapacitors can have potential applications in electronics, wearable, and implantable devices due to their suitability for mass production along with environmental safety. [ABSTRACT FROM AUTHOR]

This paper presents the synthesis of copper sulfide (CuS) electrode utilizing chemical bath deposition (CBD) and the study of the effect of complexing agent on the morphology of CuS electrode. The aim of this study is to find the ideal time for the synthesis of CuS and to find the capacitance and highest potential of the CuS electrode synthesized at the ideal time. In this project, CuS solution is formed using copper (II) sulphate (CuSO4) solution, thioacetamide solution, and a complexing agent which is citric acid. Homogeneous ultrathin nanospheres of CuS thin films have been successfully developed on nickel foam (NF) by simple and low-cost CBD method which is a promising electrode material for high-performance supercapacitors. The CBD process was carried out at different time intervals which are 30, 60, 90 and 120 min to find the ideal deposition time for CuS/NF electrode fabrication. The surface morphological analysis showed uniform growth of CuS nanospheres on NF surface. Structural analysis confirms the formation of hexagonal crystal structure of CuS. The electrochemical performances were tested by cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance techniques. The best capacitance that was recorded by CuS fabricated at 60 min with a specific capacitance of 615 F/g at 1 A/g current density. Hence, the ideal deposition time of CuS/NF electrode fabrication for high supercapacitor performance is 60 min. The encouraging results suggest that CuS nanoflakes prepared by chemical bath deposition can serve as promising electrode materials for high performance supercapacitors in the future. [ABSTRACT FROM AUTHOR]

The design of multifunctional materials for energy storage and conversion systems is vital in addressing present global energy issues. In this work, we have prepared a highly active and economical hybrid material comprising ZnO and Nb2O5, integrated with g-C3N4 (Nb@ZGCN) through the simple chemical method followed by calcination process. The resultant Nb@ZGCN electrode delivered a specific capacitance of 122.3 F g−1 at a current density of 1 A g−1 and maintained 71% of its initial value at a current density of 4 A g−1 in a 6 M KOH electrolyte. This hybrid electrode exhibited superb cyclic stability of 105% even after 2000 cycles at 4 A g−1 with an increased coulomb efficiency than the first cycle which is close to 100%. Additionally, the prepared hybrid material was further applied for electrocatalytic hydrogen evolution reaction (HER), delivering a small overpotential of 252.1 mV to achieve a current rate of 10 mA cm− 2 along with long-term durability in a 1 M KOH medium. The synergistic interaction between the ZnO, Nb2O5 and graphitic carbon nitride in the hybrid structure leads to abundant electroactive sites that remarkably improve the supercapacitive and HER activities. These results suggest that the developed hybrid material can be further exploited as an electrode material for supercapacitor and water splitting applications. [ABSTRACT FROM AUTHOR]

In this paper, a 150-µm-thick flexible γ-Al2O3 nanofiber separator with the tensile strength of 0.22 MPa was prepared from the low-cost aluminum chloride hydroxide/polyvinyl alcohol (PVA)/water precursor materials by electrospinning method. The resultant separator with 3D interconnection nanostructure revealed fiber diameters in the range of 200 to 500 nm. The specific surface area, porosity, and electrolyte uptake of γ-Al2O3 nanofiber separator are 31.5 m2/g, 55%, and 1021%, higher than that of commercial polypropylene (PP) separator and glass fiber (GF) separator. The supercapacitor assembled with the γ-Al2O3 nanofiber separator exhibited a high discharge specific capacitance of 93 F/g at the current density of 1A/g, and there is almost no capacity decay after 10,000 cycles. The energy density of supercapacitor assembled with γ-Al2O3 nanofiber separator is 31.7 Wh/kg at the power density of 562.6 W/kg. Meanwhile, the rate performance of the supercapacitor is improved significantly due to the existence of porous structure and low ion diffusion resistance (0.78 Ω) of γ-Al2O3 nanofiber separator. In addition, the thermal performance of the γ-Al2O3 nanofiber separator is also excellent, which has almost no shrinkage at the temperature of 200 °C and cannot be ignited. Therefore, the obtained γ-Al2O3 nanofibers could serve as a promising alternative separator for a new generation of safe, high-power supercapacitors. [ABSTRACT FROM AUTHOR]

A new integrated electrode-separator-electrolyte hydrogel is designed and prepared, which is composed of organic liquid crystal, polyvinyl alcohol (PVA), polyaniline (PANI), and reduced graphene oxide (rGO). The organic liquid crystal is introduced into PVA hydrogel, effectively improving compatibility between active materials and hydrogel matrix. The PANI active material is in situ polymerized in hydrogel to prepare PANI-double-network hydrogel. It simultaneously acts as electrode, separator, and electrolyte for assembling flexible solid-state supercapacitor. It obtains an area-specific capacitance of 160.2 mF/cm2 and a power density of 101.5 μW/cm2 with an energy density of 21.0 μWh/cm2. This work provides a new method to reduce interfacial resistance of electrode, separator, and electrolyte of flexible solid-state supercapacitor, further improving its electrochemical performance. [ABSTRACT FROM AUTHOR]

The supercapacitive properties of the polythiophene (PTh) and its composites with iron dust synthesized by chemical oxidative polymerization are investigated. The UV–Vis, FTIR, TGA, XRD, SEM, and EDX were used to characterize the composites. Iron (Fe) dust is inserted into PTh matrix as confirmed by FTIR, UV–Vis, EDX, and XRD analysis. The TGA shows that composites have higher thermal stability than pure PTh. The SEM reveals highly porous and packed morphology of the composites as compared to pure PTh. Cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), and electrochemical impedance spectroscopy (EIS) show that a 1:1 ratio by mass of PTh and Fe composite displayed greater specific capacitance than pure PTh. The high specific capacitance of the composite material (428.46 F/g at 1 A/g) suggested that the material is suitable for supercapacitor electrode. Cyclic stability is also tested for 1000 cycles at a current density of 1 A/g with excellent retention of 88.89%. [ABSTRACT FROM AUTHOR]

Metal-organic frameworks (MOFs) with redox-active metal ions and a variety of organic linkers have been widely investigated as prospective electrode materials for supercapacitors. Here, we generate uniformly dense spherical particles on a nickel foam substrate by a simple and binder-free one-step electrodeposition method by adjusting the deposition conditions. The active cobalt in the Co-MOF thin films can provide a large number of redox sites for the electrochemical reaction, while the uniform binder-free Co-MOF structure can keep enough contact area with the electrolyte to reduce the ion transport resistance. As-prepared CTB-0.9 (Co-MOF with a deposition voltage of − 0.9 V) thin film has a specific capacitance of 797.5 F g−1 at a current density of 1 A g−1, exhibiting excellent electrochemical properties. An asymmetric supercapacitor with CTB-0.9 as the positive material and activated carbon as the negative material also demonstrates competitive electrochemical performances, which has a high energy density of 34.3 Wh Kg−1 at a power density of 36,317.6 W Kg−1. This work may open up an effective approach to realize the electrosynthesis of Co-MOF films, promoting the utilization of Co-based MOFs in energy storage and conversion fields. [ABSTRACT FROM AUTHOR]

High-energy global requirements have caused a renewed interest in studying and developing new and improved energy storage devices and, precisely, the electrode materials that compose them, which play a fundamental role in determining the device's performance. Carbon materials are first-class candidates due to their high electrical conductivity, chemical stability, and surface area. Although several carbon materials and their precursors have been studied, melamine sponges stand out for their nitrogen content, allowing them to act as a template and precursor for N-doped, ultralight carbon materials with good mechanical properties and a controlled pore size distribution. This work reports a simple and quick methodology to form ultralight and flexible carbon foam, along with the influence of the pyrolysis temperature on the physicochemical and electrochemical properties of 3D carbonaceous substrates used for energy storage and synthesized from melamine sponges. The substrates exhibit higher 3D porous structure than previously reported materials, with an average pore diameter of 80–90 µm. This morphology, added to the N content, promotes the remarkable electrochemical behavior (MS–950 °C) and cycling stability (MS–1000 °C) of almost 100% of capacitance retention after 10,000 cycles (≈ 60 F/g @1 A/g). [ABSTRACT FROM AUTHOR]

Nanostructured materials incorporating transition metal sulfides have demonstrated considerable potential across various applications, particularly in the realms of energy production and storage. Sulfide-based material preparation is a challenging and costly procedure that requires a high temperature and reducing atmosphere. This work reports that manganese cobalt sulfide (MCS) and reduced graphene oxide composite manganese cobalt sulfide (rMCS) were successfully prepared through a hydrothermal method. Various characterization techniques were employed to analyze the prepared materials, including X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, Brunauer-Emmett-Teller analysis, and X-ray photoelectron spectroscopy. In a three-electrode system, MCS and rMCS electrodes exhibit an excellent specific capacitance of 1695 and 1925 F g−1 at 1 A g−1 current density respectively. MCS delivers the capacitance retention of 99% and rMCS exhibits the capacitance retention of 100% capacitance retention over 5000 consecutive cycles. The constructed asymmetric supercapacitor electrode (rMCS//rGO) exhibits the energy and power density of 64 Wh kg−1 at 799 W kg−1, respectively with outstanding cyclic stability of 97.4% even after 10,000 cycles. The exceptional electrochemical properties of MCS with rGO composite electrode indicate that they would make an outstanding electrode material for cutting-edge energy storage devices. [ABSTRACT FROM AUTHOR]

To investigate the effect of Co(OH)2 on the performance of the special capacitor, graphene was holed (HG) using microwave and KMnO4 and electrostatically sprayed with CNT to prepare a laminated structure bamboo woodceramics matrix (C/HG@BE). Then, Co(OH)2 was electrodeposited on the matrix to form a supercapacitor electrode (C/HG@BE-Co-x). The results showed that the Mn nanoparticles generated by KMnO4 under the action of microwave were partially embedded in the graphene sheet mesh and formed holes in the graphene sheet after removal. The matrix had a clear laminated structure and good electrical conductivity. The electrical resistivity was approximately 0.163 Ω cm at 1000 ℃ sintering temperature and remained low after the electrode was modified Co(OH)2. Meanwhile, the Co(OH)2 was uniformly deposited on the surface and within pores of the wall of the matrix and anchored by PPy to reduce fall. The electrode of C/HG@BE-Co-1500 modified with Co(OH)2 exhibited a good pseudocapacitance effect. At the current density of 0.1 A/g, the specific capacitance was approximately 255.12 F/g, and the retention of specific capacitance was maintained at 83.75% after 10000 cycles. When the energy density was 40.78 Wh/kg, the power density was 480 W/kg, indicating excellent electrochemical performance, which contributed of the synergistic action of electronic double layer capacitor and pseudocapacitance. [ABSTRACT FROM AUTHOR]

This study presents the development of a green-synthesized NaTiO₂/activated carbon (AC) nanocomposite as a high-performance electrode material for next-generation sodium-ion capacitors. Using Moringa oleifera extract, the NaTiO₂/AC nanocomposite was synthesized and characterized for its electrochemical properties. The material demonstrated a high specific capacitance of 230 F/g at 5 mV/s, with excellent cycling stability, retaining 78% of its capacitance after 4000 cycles. Electrochemical impedance spectroscopy results showed a low electrolyte resistance (Re) of 13.3 Ω and a working electrode resistance (Rw) of 0.7 Ω, suggesting efficient charge transfer and ion diffusion. The nanocomposite also exhibited notable energy and power densities of 69 Wh/kg and 144 W/kg, respectively, making it a strong candidate for energy storage applications. Theoretical calculations using density functional theory further supported the experimental findings by revealing that Ti d and O p orbitals contribute to a reduced band gap of 3.134 eV, enhancing the material's electronic properties. The synergy between NaTiO₂ and activated carbon significantly improves the composite's electrochemical performance, resulting in superior energy storage capabilities. These combined experimental and theoretical insights position the NaTiO₂/AC nanocomposite as a promising electrode material for durable and efficient sodium-ion capacitors, contributing to the development of sustainable energy storage technologies. [ABSTRACT FROM AUTHOR]

The electrospun light rare earth orthochromites RCrO3 (R = La, Pr, Nd, Sm, Eu) nanofibers have perovskite-type orthorhombic structures. Raman spectra proved the typical vibration modes of the rotation, bending, and stretching of the CrO6 octahedra in RCrO3 nanofibers. The rare earth element with large ion radius, low electronegativity, and remarkable affinity for oxygen, and the rich redox reaction of Cr endow RCrO3 a potential energy storage material for supercapacitors. It is highly significant to investigate the electrochemical properties of RCrO3. The electrochemical properties of the RCrO3 nanofibers as supercapacitor electrodes were elucidated. At 0.5 A/g, the LaCrO3, PrCrO3, NdCrO3, SmCrO3, and EuCrO3 nanofibers exhibited the specific capacitance values of 267.8, 132.8, 157.6, 170.5, and 170.4 F/g, respectively. First-principles density functional theory method was used to clarify the electronic structure and total density of states of the RCrO3 nanofibers. This study provides a rational design and fabrication method to pseudocapacitor electrodes. [ABSTRACT FROM AUTHOR]

This study employed lignin-sulfonated (LS) to develop biobased carbon materials (LS-Cs) through a sulfur-doping approach to enhance their physicochemical properties, adsorption capabilities, and energy storage potentials. Various characterization techniques, including BET surface area analysis, SEM imaging, XPS, Raman spectroscopy, and elemental composition (CHNS), were employed to assess the quality of the LS-Cs adsorbent and electrode samples. Response Surface Methodology (RSM) was utilized for optimizing the two main properties (specific surface area, ABET, and mesopore area, AMESO) by evaluating three independent factors (i.e., activation temperature, ZnCl2:LS ratio, and sulfur content). According to the statistical analysis, ABET and AMESO were affected by ZnCl2 and sulfur content, while the pyrolysis temperature did not affect the responses in the studied conditions. It was found that increasing the ZnCl2 and sulfur contents led to an increment of the ABET and AMESO values. The LS-C materials exhibited very high ABETvalues up to 1993 m2 g−1 and with predominantly mesoporous features. The S-doping resulted in LS-Cs with high sulfur contents in their microstructures up to 15% (wt%). The LS-C materials were tested as adsorbents for sodium diclofenac (DCF) adsorption and reactive orange 16 dye (RO-16) and as electrodes for supercapacitors. The LS-Cs exhibited excellent adsorption capacity values for both molecules (197–372 mg g−1) for DCF, and (223–466 mg g−1) for RO-16. When tested as electrodes for supercapacitors, notably, LS-C3, which is a doped sample with sulfur, exhibited the best electrochemical performance, e.g. high specific capacitance (156 F/g at 50 mV/s), and delivered an excellent capacitance after 1000 cycles (63 F/g at 1 A/g), which denotes the noteworthy capacitive behavior of the S-doped electrode. Thus, the present work suggests an eco-friendly resource for developing effective, productive carbon materials for adsorbent and electrodes for SC application. However, further studies on the complete application of these materials as adsorbents and electrodes are needed for a deeper understanding of their behavior in environmental and energy storage applications. [ABSTRACT FROM AUTHOR]

Eco-friendly and cost-effective biomass-derived materials have garnered significant attention for producing porous activated carbon with a high surface area, particularly for applications in supercapacitors. In this study, the stalks of Gossypium hirsutum L. flower were utilized to prepare activated carbon (AC), and thus act as a supercapacitor electrode material. Furthermore, carbon has undergone doping with nitrogen (N) and sulfur (S) atoms to enhance the surface properties of the activated carbons. Out of all the recently prepared materials based on activated carbon, the sulfur-doped activated carbon (S-doped AC) exhibits notable features, particularly in terms of high surface area properties. In 1 M Na2SO4 electrolyte, the S-doped AC electrode presents the specific capacitance of 424 F g− 1 at 1 A g− 1 with a remarkable rate capability of 64.8% at 5 A g− 1 of current density in an electrode electrochemical system. Furthermore, the capacitance retention of 95% after 5000 charge/discharge cycles at 5 A g− 1. The symmetric device composed of S-doped AC//S-doped AC material demonstrates a cell-specific capacitance of 153.6 F g− 1 at 1 A g− 1, along with impressive energy and power densities of 41.8 Wh kg− 1 and 700 W kg− 1, respectively, at 1 A g− 1. At 10 A g− 1, the symmetric device maintains energy and power densities of 7.7 Wh kg− 1 and 7000 W kg− 1, respectively. The device demonstrates cyclic stability, retaining 89% of its initial specific capacitance after undergoing 5000 charge/discharge cycles at 10 A g− 1. Therefore, activated carbon derived from the stalks of Gossypium hirsutum L. flowers emerges as a promising avenue for creating cost-effective, large-scale materials suitable for applications in energy storage devices. [ABSTRACT FROM AUTHOR]

A novel quaternary nanocomposite has been developed using a cost-effective and user-friendly method called electro-spraying. This composite consists of poly(aniline-co-pyrrole), Graphene Oxide (GO), and Iron Oxide (Fe3O4), aimed at achieving improved electrochemical stability and performance. The composite electrodes displayed an impressive specific capacitance of 950 Fg–1 at a current density of 0.5 Ag–1 when tested in a 1 M H2SO4 solution. Furthermore, even after 2000 cycles at a current density of 1 Ag–1, the electrode exhibited an outstanding capacitance retention rate of 91%, showcasing its remarkable stability and long-lasting performance. These exceptional properties can be attributed to the synergistic effects arising from the combination of the conducting polymer, metal oxide, and graphene oxide components within the electrode material. Additionally, significant advancements in other electrochemical properties make this nanocomposite a promising candidate for use as an electrode material in supercapacitors. [ABSTRACT FROM AUTHOR]

Using Euryale ferox shells as biomass raw material, porous carbon samples were prepared by conventional hydrothermal carbonization and microwave-assisted hydrothermal carbonization followed by KOH activation. Effects of hydrothermal heating method and reaction time on the formation of porous carbon structure were systematically studied. It is found that compared with conventional hydrothermal carbonization, microwave-assisted hydrothermal carbonization can rapidly promote the hydrolysis of biomass and form hydrochar with certain pore structure. This is conducive to improving the activation efficiency and preparing porous carbon with rich pore structure. At the same time, microwave-assisted hydrothermal carbonization can improve the content of oxygen-containing functional groups of porous carbon in a short time. In a three-electrode system, PC-M10m (405 F g−1) has a higher specific capacitance than PC-H6h (388 F g−1) at a current density of 0.5 A g−1. PC-M10m charges and discharges 20,000 times at 10 A g−1 current density, and the capacitance retention rate is 100%. This work provides useful results for developing suitable hydrothermal carbonization process for efficient conversion of biomass into high-performance supercapacitor electrode materials. [ABSTRACT FROM AUTHOR]

In this study, the synthesis of magnesium-doped copper ferrite, namely CuxMg1−xFe2O4 (x = 1, 0.9, 0.7, and 0.5), is achieved using a facile microwave route, and the cubic crystalline structure, functional group, and nanostructured materials are discussed. The electrochemical studies of the magnesium-doped copper ferrite (MCF) are carried out by assembling a three-electrode conventional electrochemical cell with MCF samples as working electrode, a platinum wire as counter electrode, a silver (Ag)/silver chloride (AgCl) as reference electrode, and 2 M KOH aqueous solution as electrolyte. The study of the electrochemical performance of Mg-doped and undoped copper ferrite electrodes reveals that they show battery-type behavior with the transfer of two electrons (Mg to Mg2+) in 2 M KOH electrolyte in the potential window of 0.45 V to 0.35 V. Further, un-oxidized MgO oxidizes, leading to a quasi-conversion reaction. Additionally, the electrode (MCF) exhibits a greater specific capacity of 737.5 F g−1 at 1 A g−1. It is found that the MCF3 electrode retains 70% of its initial capacitance, which is higher than the CF electrode (33%), after 4000 continuous galvanostatic charge/discharge (GCD) cycles. An asymmetric supercapacitor cell is fabricated using MCF as the positive electrode, activated carbon (AC) as the negative electrode, 2 M KOH as the electrolyte, and polypropylene as the separator. The fabricated MCF//AC supercapacitor yields maximum specific energy of 62.61 W h kg−1 at specific power of 1168 W kg−1. These electrochemical features suggest that MCF is a feasible candidate material for developing supercapacitor electrodes. [ABSTRACT FROM AUTHOR]

This article describes the synthesis of CoFe2O4 nanoparticles, which can be used to form an anode for supercapacitor applications. The CoFe2O4 nanoparticles were synthesized via a hydrothermal route. The structural parameters of the prepared samples were characterized by x-ray diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM), and the supercapacitive behavior was evaluated by cyclic voltammetry plots, galvanostatic charge–discharge plots, and electrochemical impedance spectroscopy (EIS). Rietveld refinement confirmed the spinel structure of the CoFe2O4 nanoparticles with space group Fd3m. The FE-SEM micrographs confirmed the spherical shape of the CoFe2O4 nanoparticles, with a mean particle size of 58 nm. The electrochemical performance of the samples was checked in different aqueous electrolytes: Na2SO4 and KOH. The nanoparticles exhibited differences in capacitive behavior in different aqueous electrolytes, with higher specific capacitance (362 F/g) in the KOH electrolyte due to its greater molar ionic conductivity in comparison to the Na2SO4, and a low resistance value obtained from impedance measurements was observed for CoFe2O4 nanoparticles. The cyclic stability of CoFe2O4 in KOH electrolyte, with 82.16% retention after 2000 cycles at current density of 1 A/g, evidenced its outstanding performance, with exceptionally high specific capacitance of 314 F/g. [ABSTRACT FROM AUTHOR]

2D transition metal oxides have created revolution in the field of supercapacitors due to their fabulous electrochemical performance and stability. Molybdenum trioxides (MoO3) are one of the most prominent solid-state materials employed in energy storage applications. In this present work, we report a non-laborious physical vapor deposition (PVD) and ultrasonic extraction (USE) followed by vacuum assisted solvothermal treatment (VST) route (DEST), to produce 2D MoO3 nanosheets, without any complex equipment requirements. Phase transition in MoO3 is often achieved at very high temperatures by other reported works. But our well-thought-out, robust approach led to a phase transition from one phase to another phase, for e.g., hexagonal (h-MoO3) to orthorhombic (α-MoO3) structure at very low temperature (90 °C), using a green solvent (H2O) and renewable energy. This was achieved by implementing the concept of oxygen vacancy defects and solvolysis. The synthesized 2D nanomaterials were investigated for electrochemical performance as supercapacitor electrode materials. The α-MoO3 electrode material has shown supreme capacitance (256 Fg−1) than its counterpart h-MoO3 and mixed phases (h and α) of MoO3 (< 50 Fg−1). Thus, this work opens up a new possibility to synthesize electrocapacitive 2D MoO3 nanosheets in an eco-friendly and energy efficient way; hence can contribute in renewable circular economy. [ABSTRACT FROM AUTHOR]

The synthesis of cobalt nanocrystal-graphene quantum dot-Ti3C2TX monolithic film electrode (Co-GQD-Ti3C2TX) is reported via self-assembly of Ti3C2TX nanosheets induced by protonated arginine-functionalized graphene quantum dot and subsequent reduction of cobalt (III). The resulting Co-GQD-Ti3C2TX shows good monolithic architecture, mechanical property, dispersibility and conductivity. The structure achieves excellent supercapacitor and sensing behavior. The self-charging supercapacitor produced by printing viscous Co-GQD-Ti3C2TX hydrogel on the back of flexible solar cell surface provides high specific capacitance (296 F g−1 at 1 A g−1), high-rate capacity (153 F g−1 at 20 A g−1), capacity retention (98.1% over 10,000-cycle) and energy density (29.6 W h kg−1 at 299.9 W kg−1). The electrochemical chip produced by printing Co-GQD-Ti3C2TX hydrogel on paper exhibits sensitive electrochemical response towards uric acid. The increase of uric acid between 0.01 and 800 μM causes a linear increase in differential pulse voltammetry signal with a detection limit of 0.0032 μM. The self-powered sensing platform integrating self-charging supercapacitor, electrochemical chip and micro electrochemical workstation was contentedly applied to monitoring uric acid in sweats and shows one broad application prospect in wearable electronic health monitoring device. [ABSTRACT FROM AUTHOR]

Polyaniline/hydrothermally treated graphite disk (PANI/HT-G disk) with 3D microporous structure and large surface area is suggested as an effective and inexpensive electrode in the supercapacitor application. The PANI/HT-G disk was easily obtained from uniform mixing of commercial and low-cost azodicarboxamide (ADCA-C2H4O2N4) and graphite powders, pressing beneath optimum pressure pursued by treatment at 250 °C to release various gases (NH3, N2, CO) originated from ADCA decomposition (creating porous structure with large surface area) and finally electrodeposition of polyaniline onto the previously HT-G disk. The PANI/HT-G disk demonstrated weak ohmic drop and favorite areal capacitance of 1490 mF cm−2 at 2/0 mA cm−2 in aqueous 1.0 M sulfuric acid electrolyte under the three-electrode system. When PANI/HT-G disk was assembled as symmetric supercapacitor disk device with a PVA/H2SO4 gel, the areal capacitance was 232 mF cm−2 at 2/0 mA cm−2 with high operation voltage. The supercapacitor device had an energy density of 93.17, 83.32, 86, 63.96, 60.2, 48.37, and 44.8 mWh cm−2 in the power density of 2.58, 3.22, 3.87, 4.51, 5.16, 5.8, and 6.45 mW cm−2. It is expected that the strategy introduced in this work could guide designers for scalable fabrication of low-cost supercapacitor disks. [ABSTRACT FROM AUTHOR]

Nickel ferrites have served as electrode materials in energy storage applications such as batteries and supercapacitors in comparison to other metal oxides, they have a higher theoretical capacitance range. Pristine metal oxides are poor candidates as electrode components in electrochemical applications because of their tendency to aggregate and their less specific surface areas. Herein, we reported wet impregnation method to incorporate Nickel Ferrite (NiFe2O4) to multiwalled carbon nanotubes (MWCNTs) for improved electrochemical performance of nickel ferrites (NiFe2O4). The synthesized materials attained good crystallinity confirmed by X-ray diffraction (XRD). NiFe2O4 nanoparticle adhesions on multiwalled carbon nanotubes have been confirmed by scanning electron microscopy (SEM). UV-DRS was used to measure the bandgap for optical studies. Cyclic Voltammetry (CV), Galvanostatic Charge/Discharge (GCD), and Electrochemical Impedance Spectroscopy (EIS) investigations for supercapacitor applications revealed that synthesized materials demonstrated good electrochemical potential, but MWCNTs supported NiFe2O4 composite attained exceptionally high specific capacitance (CV: 830 F g−1 at 5 mV s−1, GCD:343 F g−1 at current density of 0.1 A g−1) with capacitance retention of 98% at the current density of 0.8 A g−1 after 3500 stability cycles. [ABSTRACT FROM AUTHOR]

This paper presents a novel binder-free electrochemical synthesis of a porous ternary composite comprising polyaniline/multiwall carbon nanotubes decorated with silver nanoparticles (Ag@PANI/MWCNTs), which serves dual functions as a photocatalyst for methylene blue degradation and as an electrode for high-performance supercapacitors application. Various characterization techniques confirm that the synthesized Ag@PANI/MWCNTs composite exhibits excellent optical, chemical, electrical, structural, morphological, electrochemical and photocatalytic characteristics. The composite exhibits excellent electrochemical and photocatalytic efficacy attributed to its porosity, higher surface area, conductivity and rapid redox properties. Electrochemical tests reveal specific capacitance of 862 F/g, energy density of 65.78 Whkg−1, power density of 444.44 Wkg−1 and cycling stability with 79% capacitance retention even after 10,000 cycles. As a photocatalyst, the composite achieves approximately 95% degradation in 25 min with reusability up to five cycles. It also exhibits high transient photocurrent responses (0.36 mA/cm2) and a high-rate constant (0.13 min−1), confirming excellent photocatalytic activity. The synergistic effect of PANI/MWCNTs and the incorporation of Ag nanoparticles contribute to the outstanding performance of the synthesized nanocomposite. Thus, it is expected that the synthesized Ag@PANI/MWCNT is a promising ternary composite which may prove to be a noble material for photocatalytic and energy storage-related devices. [ABSTRACT FROM AUTHOR]

In this article, nickel hydroxide nanocrystals are synthesized for the first time by a simple air-plasma electrolysis setup. Aqueous solution of nickel nitrate is used as the electrolyte. Once the electrolysis is started, a green powder is produced at the contact point of the plasma and the solution. Electron microscopy (FESEM and TEM) of the powder indicates that most of the particles are spherical with 25–30 nm size. Elemental analysis, Fourier transform infrared spectroscopy and X-ray diffraction pattern reveal that the powder is nano-crystalline Ni(OH)2⋅0.75H2O with rhombohedral structure (or α-Ni(OH)2). To evaluate the lattice strain and dislocation density, the methods of Scherrer, Williamson–Hall, Williamson–Smallman and also Halder–Wagner are used. Comparisons show that the Halder–Wagner method provides more accurate results. The size of the nano-crystallites is estimated to be about 2.38 nm by this method, and the strain and dislocation density are obtained at 0.3299 and 17.72 line m−2, respectively. The results of this research confirm that the room-temperature atmospheric plasma electrolysis can be a promising and efficient candidate for the synthesis of hydroxide nanocrystals, which may have wide applications in the energy storage systems and supercapacitor industries. [ABSTRACT FROM AUTHOR]

Binary transition metal chalcogenides and reduced graphene oxide exhibit significant potential for energy storage devices due to their superior electronic conductivity and capacity, surpassing that of single-metal sulfides, owing to their more extensive redox reactions. In this report, we introduce a novel synthesis method for producing a mixed-phase MnSe2/CoSe2 nanocomposite wrapped with reduced graphene oxide (rGO) sheets, designed specifically for supercapacitor applications. The MnSe2/CoSe2 hybrid material was synthesized using an ultrasonic assisted hydrothermal technique, followed by the preparation of the rGO/MnSe2/CoSe2 hybrid composite. The structural characterization was conducted employing x-ray diffraction (XRD), scanning electron microscopy (SEM), x-ray photoelectron spectroscopy (XPS) and Raman techniques. Brunauer–Emmett–Teller (BET) analysis demonstrated a significant specific surface area (66.5 m2/g) and a pore size distribution of 28.4 nm in rGO-MnSe2/CoSe2. The interconnected ultrathin rGO nanosheets and conductive carbon layer contributed to the exceptional conductivity and stability achieved by the rGO/MnSe2/CoSe2 composite electrode. The electrochemical performance was assessed using a three-electrode setup in a 3 M KOH solution, with nickel foam as the current collector. The working electrode, consisting of rGO/MnSe2/CoSe2, acetylene black and PVDF in an 80:15:5 weight ratio, demonstrated specific capacitance of 1214 F g−1 and cycling stability of 88% retention after 5000 cycles at 1 A g−1. An asymmetric supercapacitor, constructed using a tailored electrode composition, achieved energy density of 28.6 Wh kg−1 at 2100 W kg−1 and high power density of 888 W kg−1 at 49.7 Wh kg−1. [ABSTRACT FROM AUTHOR]

The rising global energy demand calls for the development of highly efficient energy storage devices, particularly supercapacitors with remarkable power density. Because of its high surface area, activated carbon (AC) is crucial as a supercapacitor electrode material. X-ray irradiation of AC leads to modifications in its surface chemistry by altering the sp2 hybridization of the surface carbons. In the current work, we present x-ray irradiation studies on the supercapacitive properties of AC prepared by adopting an oil wick lamp method using soot derived from waste soybean oil. The activated soot is irradiated at a dose rate of 16 mGy/s under a 60 kV x-ray source and investigated as an electrode active mass for an electric double-layer capacitor (EDLC). The device studies reveal that x-ray irradiation is crucial in determining the sample's physisorption and energy storage properties. The irradiated sample demonstrates high specific power density (135.9 W kg−1) and specific energy density (3.2 Wh kg−1). The energy density of the irradiated AC soot electrode sample is nearly double that of AC, i.e., 3.2 Wh kg−1 versus 1.6 Wh kg−1, respectively, making it a potential candidate for efficient electrodes in EDLC devices. The internal resistance of the supercapacitor shows a reduction from 25.5 Ω to 24.1 Ω after irradiation, thereby increasing the electrode conductivity. The investigations in the current work reveal a significant enhancement of the energy storage capacity of x-ray-irradiated AC for high-performance supercapacitor devices. Moreover, the environmentally friendly methodology adopted to synthesize AC soot can help reduce environmental pollution and contribute to the development of sustainable energy storage devices. [ABSTRACT FROM AUTHOR]

A significant challenge in developing high-performance hybrid supercapacitors (HSCs) is the need to reasonably construct advanced architectures that consist of various components and exhibit superior electrochemical capacitance performance. The FeCoNi-layered double hydroxide (FeCoNi-LDH) porous material has a specific capacitance of 1960 F·g−1 when used as the anode material at 1 A·g−1. The FeCoNi-LDH material exhibits nanoplates with a distinct spindle morphology on their surface. Due to the combined action of the three metals and abundant oxygen vacancies, they exhibit unique rate performance and cycle stability. The electronic structure of LDH and the regulation of oxygen vacancy were confirmed by density functional theory (DFT) calculations. This suggests that the strength of hydroxide can reduce the energy required for oxygen vacancy formation in FeCoNi-LDH nanosheets and enhance ion and charge transfer, as well as electrolyte adsorption on the electrode surface. The FeCoNi-LDH//activated carbon (AC) HSC has an energy density of 53.2 Wh·kg−1 at a power density of 800 W·kg−1, surpassing other devices composed of comparable materials during the same timeframe. This study made significant advances in the design and synthesis of a ternary LDH porous structure with distinct oxygen vacancies, as well as its potential application in electrochemical energy storage. [ABSTRACT FROM AUTHOR]

Hierarchical porous carbon-based biomass is considered the most promising functional carbon-based electrode material for energy conversion and storage as a result of its abundant natural resources, multi-heteroatom self-doping and easy of modification. In this study, Ganoderma lucidum spore-derived carbon material (GLSC–2) with oxygen-rich/nitrogen-doped three-dimensional, hierarchically connected porous structure was synthesized by a two-step route of pre-oxidation in air followed by KOH etching. It is worth noting that pre-oxidation in air can not only preserve the natural cage-like structure of spores, but also introduce a significant number of oxygen-containing functional groups with the help of atmospheric oxygen. The synthesized GLSC–2 possessed high O content (14.27%), moderate N content (1.99%) and relatively high specific surface area (1524.73 m2 g−1), along with high-density micropores and narrow mesopore distribution, which were crucial for promoting rapid ion diffusion and improving the electrochemical performance of supercapacitors. Encouragingly, GLSC–2 exhibited an attractive specific capacitance of 261.13 F g−1 at 1 A g−1 and excellent rate capability. Even at a high current density of 10 A g−1, the capacitance retention rate remained at 81.60%. After 10,000 cycles of charge–discharge at 2 A g−1, the capacity retention rate and Coulombic efficiency were maintained at 98.63% and 99.19%, respectively. When assembled into a symmetric supercapacitor (GLSC–2//GLSC–2), the energy density reached 9.03 Wh kg−1, with a power density approaching 500 W kg−1. This study provides a more economical and convenient route for the production of high-performance oxygen-rich/nitrogen-doped electrode materials based on renewable biomass. [ABSTRACT FROM AUTHOR]

A porous electrode material consisting of NiCo2O4/RGO with an approximate diameter of 200 nm has been successfully fabricated. This promising porous material was derived from ZIF-67/RGO (zeolitic imidazolate framework-67 crystals doped with reduced graphene oxide sheets) through an ion exchange and etching process using Ni(NO3)2·6H2O followed by a thermal reaction. The composition was analyzed using spectroscopic and morphological techniques. The obtained porous and hollow structure of NiCo2O4/RGO contains rich active sites. Additionally, its improved performance and stability were demonstrated using potassium ferricyanide (K3[Fe(CN)]6) (PFC) and sodium hydroxide (NaOH) as an electrolyte. NiCo2O4/RGO in NaOH/PFC exhibited a maximum estimated specific capacitance of 212.5 F g−1 at 0.5 A g−1 and demonstrated excellent retention value reaching 91.7% after applying 10,000 cycles at 20 A g−1. This symmetric supercapacitor achieved an outstanding energy density (Ed) of 75.54 Wh kg−1 at a power density (Pd) of 1.6 kW kg−1 at 0.5 A g−1. Surprisingly, there is a 2.5-fold enhancement in Ed (from 32.44 to 75.54 Wh kg−1) of NiCo2O4/RGO through the addition of 0.3 M PFC into 3 M NaOH. The results indicate that the NiCo2O4/RGO electrode could be ideal for supercapacitors. [ABSTRACT FROM AUTHOR]

Here, the hierarchical mesoporous-activated carbon particles obtained by KOH activation from pistachio shell wastes are modified by both the sulfonation process and CuO doping by hydrothermal heating (CuO@S-doped PSAC) for use as a supercapacitor. It is predicted that the electrochemical performance of the porous carbon electrode material obtained by such CuO doping and sulfonation process will be significantly increased with increased Faradaic capacitance. The electrochemical performance of CuO@S doped PSAC composite is systematically investigated by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and galvanostatic charge/discharge (GCD) in the presence of 1 M H2SO4, 1 M Na2SO4, and 1 M NaOH as electrolytes. The CuO@S doped PSAC-based electrode shows excellent stability with high specific capacitance up to 397.16 F/g at 0.1 A/g and 92.64% retention. Furthermore, FTIR, SEM, XRD, EDS, and nitrogen adsorption/desorption analyses are used for the characterisation of the obtained composites. Based on a significant supercapacitor performance, the synthesis strategy of carbon-based electrode material containing sulfonation and CuO modifications derived from agricultural biomass waste material is predicted to be a valuable example. [ABSTRACT FROM AUTHOR]

Efficient charge storage is a key requirement for a range of applications, including energy storage devices and catalysis. Metal-organic frameworks are potential materials for efficient charge storage due to their self-supported three-dimensional design. MOFs are high surface area materials made up of coordination of appropriate amounts of metal ions and organic linkers, hence used in various applications. Yet, creating an effective MOF nanostructure with reduced random crystal formation continues to be a difficult task. The energy efficiency and electrochemical yield of bulk electrodes are improved in this study by demonstrating an effective technique for growing MOFs over a conducting substrate utilizing electrodeposition. An exceptionally stable asymmetric supercapacitor is created when activated carbon cloth is combined with the resulting MOF structure that was directly synthesized via an electrochemical method resulting in 97% stability over 5k cycles which is higher than conventional processes. High performance in supercapacitors is ensured by this practical approach for producing MOF electrodes, making it a suitable structure for effective charge storage. Metal-organic frameworks (MOFs) are promising charge storage materials due to their high surface area, tunable pore size, and chemical diversity, but reliable and easy syntheses of MOF conductors are needed. Here, the authors report the electrodeposition synthesis of highly conductive cobalt MOF films and their application in a supercapacitor with a power density of 480 Wkg-1 and 5k cycle stability. [ABSTRACT FROM AUTHOR]

A simple and effective metal-oriented in-situ growth of zeolitic imidazole framework (ZIF-67) membranes on carbon fiber cloth (CFC) substrate has been developed, which is realized via solution immersion with the assistance of electrodeposited active cobalt layer. Tuning the subtle factors on membrane fabrications, dense and continuous ZIF-67 membrane composed of intergrown polyhedron crystals successfully forms on the CFC surface. Evaluated as binder-free integrated electrodes for supercapacitors, the ZIF-67/CFC delivers a high areal specific capacitance of 1470 mF cm−2 at 1 A cm−2 and excellent cycling stability (over 91% capacitance retention after 10,000 charge–discharge cycles). That could be ascribed to the integrated structure of ZIF-67 membrance with underlying CFC substrate, which not only prevents ZIF-67 accumulation and insures high electroactive surface areas but also improves conductivity and structural stability of electrodes. A simple and effective metal-oriented in-situ growth of zeolitic imidazole framework (ZIF-67) membranes on carbon fiber cloth (CFC) substrate has been developed, which is realized via solution immersion with the assistance of electrodeposited active cobalt layer. [ABSTRACT FROM AUTHOR]

This work describes how to easily make NiO hollow sphere composites using waste sugarcane bagasse for use in supercapacitor applications. NiO hollow spheres (NOHSs) nanomaterialis effectively synthesized through the nano carbon sphere (CS) template. A core-shell structure was created on the carbon sphere's surface by NiO nanoparticles that were several nanometers in size. The structural and morphological of the synthesized materials were investigated by X-ray diffraction (XRD) and Scanning electron microscope (SEM). The energy-dispersive X-ray spectroscopy (EDS) was used to confirm the presence of the elements in NOHS. The electrochemical behaviour of hierarchical CSs and NOHSs electrode was examined through cyclic voltammetry (CV), Galvanostatic charge/discharge (SC) and electrochemical impedance spectroscopy (EIS). In GCD analysis, NOHSs electrode showed a concentrated specific capacitance (Csp) of 913.79 F/g at 5 A/g current density. The porous conductive carbon with macro pores that speeds up the transit of electron and electrolyte ions causes noticeably better capacitive behavior. [ABSTRACT FROM AUTHOR]

Here, the hierarchical NiCo2O4 nanoarray grown on Ni foam with various morphologies is designed and synthesized for application in electrode of supercapacitor by a soft-template-assisted hydrothermal approach. The effect of NiCo2O4 nanoarray morphology on electrochemical performance of supercapacitor is investigated in detail. It is found that the NiCo2O4 hierarchical nanosheet/nanofiber array shows large area capacitance (8.6F cm−2) and good cycling stability (81.0%) after 3000 cycles. Moreover, a new machine learning method is developed to simulate and predict the effect of electrode material's morphology on its electrochemical stability. Compared with experimental results, it exhibits high prediction accuracy with a small RMSE of 0.6595 and a large R2 of 0.9099. This study provides a facile method to design morphology of electrode materials for optimizing electrochemical stability. [ABSTRACT FROM AUTHOR]

Lithium-ion capacitors (LICs) offer high-rate performance, high specific capacity, and long cycling stability, rendering them highly promising for large-scale energy storage applications. In this study, we have successfully employed a straightforward hydrothermal method to fabricate tin disulfide/graphdiyne oxide composites (SnS2/GDYO). GDYO serves to mitigate the volume expansion of SnS2 nanosheets during charge–discharge processes and concurrently enhances their electrical conductivity. Compared to SnS2, SnS2/GDYO as a negative electrode material for lithium-ion batteries (LIBs) exhibits superior rate performance and cycling stability. Based on this, SnS2/GDYO-based LICs demonstrate outstanding electrochemical performance, with a maximum energy density of 75.6 Wh kg−1 and a peak power density of 10 kW kg−1. Even after 2000 cycles, the capacity retention remains impressively high at 66.1%. Consequently, SnS2/GDYO emerges as a highly promising negative electrode material in LICs for future applications. [ABSTRACT FROM AUTHOR]

A simple solid-state method was developed for large-scale growth of spinel nickel cobaltite (NiCo2O4) nanoparticles on the surface of N-doped reduced graphene oxide nanosheet (N-rGO) as the enhanced performance electrode for electrochemical capacitors. The synthesis involves the room-temperature solid state reaction of a bimetallic (Ni, Co) hydroxide precursor and subsequent thermal transformation to NiCo2O4 nanoparticles on the N-rGO support. Morphological analyses reveal that, with loading rate 49 wt%, NiCo2O4 nanoparticles with an average size of around 12 nm are formed and uniformly dispersed on the surface of N-rGO nanosheets (NiCo2O4/N-rGO). Electrochemical measurements of NiCo2O4/N-rGO composites display a high specific capacitance of 1135 F g− 1 (based on NiCo2O4) at a current density of 1 A g− 1, and excellent cycling performance (100% capacitance retention after 2000 cycles) even at a very high current density of 8 A g− 1, which are significantly higher than that of NiCo2O4 nanoparticles prepared without using N-rGO. This much enhanced electrochemical performance is enabled by both the well-dispersed NiCo2O4 nanoparticles that offer large accessible surface area and the mesoporous structure of NiCo2O4/N-rGO composites that facilitate electrons/ions transport. The facile two-step synthesis process developed in this work is promising to prepare electrode materials for high-performance electrochemical capacitors. [ABSTRACT FROM AUTHOR]

In this study, manganese carbonate (MnCO3) microspheres were used as self-templates for the synthesis of hollow and radially porous MnO2 via an oxidation-etching process. Then, in situ polymerization of aniline was conducted with and without 3-aminopropyl triethoxysilane (APTES) grafting agent, resulting in the formation of PANI-grafted MnO2 (MGP) and PANI-coated MnO2 (MP), respectively. The electrochemical performances were evaluated in a three-electrode configuration using a 1 M H2SO4 aqueous electrolyte solution. Both samples showed high-specific capacitances owing to the unique MnO2 structure with radial cavities, which facilitate ion diffusion and effectively accommodate volume expansion during cycling. The MGP exhibited ~ 30% higher specific capacitance (765 F g−1 and 586 F g−1 at 0.25 A g−1) and extended cycle life (80% retention after 14,000 cycles) compared to the MP. The results demonstrate that the charge transfer efficiency and structural stability of MGP are enhanced by the formation of covalent bonds between MnO2 and PANI through grafting. [ABSTRACT FROM AUTHOR]

Recently, supercapacitors (SCs) have emerged as one of the most promising energy storage devices, which can be attributed to their exceptional power density, rapid charge–discharge rate, and superior cycling stability. Despite the progress made in the signal metal oxide of SCs, several challenges still need to be addressed, including the poor electrical conductivity, unsatisfactory cyclic stability, and low energy density. It is crucial to develop innovative composite materials with synergistic effects to address these issues. In this study, the cobalt oxide and Co3O4@NiCo2O4 composite were successfully synthesized on Ni foams by a hydrothermal method. Composite electrodes featured by the hierarchical core–shell structures were identified as an effective approach for improving the electrochemical performance of SCs. Noteworthily, the as-fabricated core–shell structures demonstrated excellent specific capacitance of 1514 F g−1 at a current density of 1 A g−1, a stable operating voltage of 0–0.5 V and outstanding cycling stability (with almost no attenuation after 2000 cycles at a charge–discharge current density of 10 A g−1). The enhanced electrochemical behavior can be attributed to the synergistic effect between two electrode active materials and the presence of more electron and ion transport pathways. The as-prepared composite electrodes can be considered as the potential electrode materials for energy storage applications. [ABSTRACT FROM AUTHOR]

The aim of this study was to develop self-healable and robust electroconductive film based on polyaniline copolymer for application as electrode in flexible supercapacitor. For this purpose, the electroconductive polymer brushes (EPB) was elaborated. The synthesis of EPB is based on graft polymerizations of acrylamide (AAm) on poly(vinyl alcohol) (PVA) with formation of PVA-PAAm polymer brush and subsequent graft copolymerization of aniline and p-phenylenediamine on PVA-PAAm resulting in formation of EPB with electroconducting copoly(aniline-co-p-phenylenediamine) (PAPhDA). It was found that the ratio between PVA and PAAm at the first stage greatly influence the electrochemical performance of the EPBs. Electroconducting films were prepared by casting of EPB solution with subsequent drying. Investigation of electrical current distribution through the film with AFM reveal more uniform distribution of PAPhDA in EPB in comparison with reference PVA-PAPhDA and PAAm-PAPhDA samples. It was demonstrated that mechanical characteristics and electrical conductivity values of films restore at large extent after curring and self-healing under optimal relative humidity level (58%). The flexile supercapacitor cell with EPB film electrodes demonstrate specific capacitance 602 mF·cm−2 at the current density of 1 mA·cm−2 and retention 94% of initial capacitance after 5000 charge/discharge cycles. [ABSTRACT FROM AUTHOR]