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

Simplifying the design of high-performance electrodes via efficient catalyst design is critical for alkaline water electrolysis and supercapacitor applications. Towards that end, we have developed the environmentally benign synthesis of ultrathin nanosheets of NiFe-layered double hydroxides (LDH) with inbuilt oxygen vacancies (V O) in this report. These NiFe-layered double hydroxide (GNiFe-LDH- V O) materials require low overpotentials for the oxygen evolution reaction (OER, η 50 = 200 and η 100 = 220 mV) with a small Tafel slope of 52.21 mV dec−1. The ex-situ characterizations and theoretical calculations suggest that oxygen vacancies configure to a more active state, resulting in the low binding energy of oxo intermediates, and thus much lower overpotential. Besides, it could operate stably for 100 h at current densities of 100 mA cm−2 for OER. It is significant that oxygen vacancies in GNiFe-LDH- V O aid in lowering the main obstacle of multistep OER, which will provide recommendations for the development of high-efficiency catalysts through in situ activation. In addition, GNiFe-LDH- V O exhibits a high areal capacitance of 1.6024 F cm−2 at a current density of 1 mA cm−2, with a capacitance retention ratio of 96.1% after 5000 galvanostatic charge-discharge (GCD) cycles when they are used as supercapacitor electrodes. [Display omitted] • Ultrathin NiFe-LDH nanosheets with oxygen vacancies via in situ green, dissolution-precipitation process. • The introduction of oxygen vacancies generates appropriate electronic conductivity and catalytic activity. • The outstanding performance, was demonstrated through both experimental and theoretical calculations. [ABSTRACT FROM AUTHOR]

Electrochemical energy storage devices are built upon the foudations of batteries and supercapacitors. In the past decade, new pseudocapacitor‐like electrodes are intensively developed to obtain superior energy storage performance. Pseudocapacitive matarials store charge through Faradaic processes, while the electrochemical signal remains like electrochemical double‐layer capacitors (EDLCs). To address this controversy, an analytical model is introduced for evaluating the voltammograms of electrode materials. Given this, the work focuses on understanding the origin of the pseudocapacitive phenomena in the cyclic voltammetry (CV) electrochemical signal. Based on electron transfer mechanism and tunnelling effect within the atomic structure, pseudocapacitive matarials possess a high electron delocalization possibility related to the redox centers number and initiates the electrochemical potential distribution among neighboring redox sites, which is consequently observed in the electrochemical signal as the plateau feature in CV, like EDLC. First, the determination of the capacitive tendency of various electrode materials is proposed, which turns out to be relative to the redox centers number (n) and total charge (Z). Here, when this number is large, electron hopping will very likely happen. The developed model is versatile to predict rate/potential regimes for the maximum faradaic storage, and then well differentiates the pseudocapacitive and battery materials. [ABSTRACT FROM AUTHOR]

A significant amount of energy can be produced using renewable energy sources; however, storing massive amounts of energy poses a substantial obstacle to energy production. Economic crisis has led to rapid developments in electrochemical (EC) energy storage devices (EESDs), especially rechargeable batteries, fuel cells, and supercapacitors (SCs), which are effective for energy storage systems. Researchers have lately suggested that among the various EESDs, the SC is an effective alternate for energy storage due to the presence of the following characteristics: SCs offer high-power density (PD), improvable energy density (ED), fast charging/discharging, and good cyclic stability. This review highlighted and analyzed the concepts of supercapacitors and types of supercapacitors on the basis of electrode materials, highlighted the several feasible synthesis processes for preparation of metal oxide (MO) nanoparticles, and discussed the morphological effects of MOs on the electrochemical performance of the devices. In this review, we primarily focus on pseudo-capacitors for SCs, which mainly contain MOs and their composite materials, and also highlight their future possibilities as a useful application of MO-based materials in supercapacitors. The novelty of MO's electrode materials is primarily due to the presence of synergistic effects in the hybrid materials, rich redox activity, excellent conductivity, and chemical stability, making them excellent for SC applications. [ABSTRACT FROM AUTHOR]

In this investigation, we successfully synthesized bismuth oxide (Bi2O3) nanoparticles (NPs) via simple combustion method using Artocarpous heterophyllus (Jackfruit) extract as fuel. Both α and β polymorphs of bismuth oxide NPs was prepared using same Artocarpous heterophyllus fuel but there is a variation in the addition of fuel in the range of 1 mL–6 mL. The prepared NPs were characterized by utilizing spectroscopic techniques. The photocatalytic efficiencies were found to be 84 %, 93 % for both α, β forms respectively. Methylene blue dye exhibits effective degradation for β‐phase compared to α‐phase. Furthermore, Electrochemical impedance spectroscopy and sensing (CV) activities were performed. The bismuth oxide modified electrodes exhibits better sensing activity towards dopamine, ascorbic acid, lead nitrate, and results obtained from EIS data revealed the super capacitor characteristics of Bi2O3 nanoparticles. This extensive investigation assessed the effectiveness of Aspergillus Niger‐fighting drugs, as well as the antibacterial effects of synthesized nanoparticles on Staphylococcus Aureus and Escherichia Coli. Measurements of optical density were used to establish the MIC values for antifungals. The protein 4XUY has a strong binding affinity of −6.4 Kcal/mol, with four important hydrogen bond interactions (LYS51, HIS84, ASN131, and GLU238) revealed by molecular docking research. These results expand our knowledge of the therapeutic uses of bismuth oxide nanoparticles by highlighting their potential as effective antibacterial agents and by providing insightful information about how they work against pathogenic microorganisms. [ABSTRACT FROM AUTHOR]

Currently, new clean energy storage technology must be effective, affordable, and ecologically friendly so as to meet the diverse and sustainable needs of the energy supply. In this work, NiCo-LDH containing intercalated EG was successfully prepared within 210 s using an ultrafast microwave radiation technique. Subsequently, a series of characterization and systematic electrochemical tests were conducted to analyze the composition, structure, and energy storage mechanism of the NiCo-LDH material. The Ni:Co ratio of 5:5 results in the highest capacitance value of 2156 F/g at 1 A/g and an outstanding rate performance of 86.8% capacity retention rate at 10 A/g. The results demonstrated that the unique porous structure of NiCo-LDH and large layer spacing were conducive to more electrochemical reactions. Additionally, an electrochemical test was carried out on the NiCo-LDH as a hybrid supercapacitor electrode material, with NiCo-LDH-5:5 serving as the positive electrode and activated carbon as the negative electrode, the asymmetric supercapacitor can achieve a maximum energy density of 82.5 Wh kg−1 and power density of 8000 W kg−1. The NiCo-LDH-5:5//AC hybrid supercapacitors own 81.5% cycle stability and 100% coulombic efficiency after 6000 cycles at 10 A/g. [ABSTRACT FROM AUTHOR]

The hierarchical porous carbon-based materials derived from biomass are beneficial for the enhancement of electrochemical performances in supercapacitors. Herein, we report the fabrication of nitrogen-doped 3D flower-like hierarchical porous carbon (NPC) assembled by nanosheets using a mixture of urea, ZnCl2, and starch via a low-temperature hydrothermal reaction and high-temperature carbonization process. As a consequence, the optimized mass ratio for the mixture is 2:2:2 and the temperature is 700 °C. The NPC structures are capable of electron transport and ion diffusion owing to their high specific surface area (1498.4 m2 g−1) and rich heteroatoms. Thereby, the resultant NPC electrodes display excellent capacitive performance, with a high specific capacitance of 249.7 F g−1 at 1.0 A g−1 and good cycling stability. Remarkably, this implies a superior energy density of 42.98 Wh kg−1 with a power density of 7500 W kg−1 in organic electrolyte for the symmetrical supercapacitor. This result verifies the good performance of as-synthesized carbon materials in capacitive energy storage applications, which is inseparable from the hierarchical porous features of the materials. [ABSTRACT FROM AUTHOR]

Nanourchin VO2 nanostructures have been effectively synthesized by hydrothermal method. The synthesized hierarchical nanostructure has been characterized by various characterization techniques and electrochemical behaviour has been studied. X-ray diffraction analysis revealed the monoclinic phase and morphological analysis (FESEM) of VO2 showed nanourchin-like structure with arrangement of various nanorods in radial fashion. Over these nanorods, formation of secondary growth of asterisk-shape structure was observed. The width and length of nanorods were ~ 50 and ~ 75 nm, respectively. For the electrochemical measurements, 2032 type coin cells were fabricated using VO2 as electrode material. The electrochemical study of VO2 exhibited the pseudocapacitive behaviour with specific capacitance of 44 F g−1 in organic electrolyte with symmetric capacitor of two electrode system. The maximum energy density and power density were 44 and 8635 Wh kg−1, respectively. Cycling performance exhibited symmetric charge–discharge curves, and also specific capacitance was maintained up to 82% of initial value. [ABSTRACT FROM AUTHOR]

In this study, bismuth telluride–based hybrids consisting of nanosheets were successfully prepared by disproportionation induced by microwave irradiation and applied on supercapacitor electrodes. Various analytical techniques were adopted to analyze the structure and composition of Bi 2 Te 3 /Bi 2 TeO 5. The unique disproportionation (Te0→Te2++Te4+) results in an interlocking nanosheet, in which the lamellar interspersed structure on the lamella can be visualized through high-magnification scanning electron microscopy. The large layer spacing with the interspersed structure provides more storage sites for electrolyte ion interactions and allows for better stabilization of the electrode structure. Result of electrochemical studies indicates that Bi 2 Te 3 /Bi 2 TeO 5 enables a capacity of 860 F g−1 (1 A g−1) and maintains 74.5% of the initial capacity through 2000 charge/discharge cycles. The Bi 2 Te 3 /Bi 2 TeO 5 anode is integrated into an ultracapacitor to attain a remarkable energy density of 89 Wh kg−1 in 6 M KOH. [Display omitted] [ABSTRACT FROM AUTHOR]

Supercapacitors, thanks to their unique properties, are considered among the main future energy storage systems. However, problems such as low energy density relative to batteries, spontaneous discharge, and low cell voltage have limited their widespread use. In this regard, the development of active and efficient materials is known as a viable solution. Thus, in this study, a hybrid supercapacitor made of nickel oxide and graphene was investigated. Nickel oxide and graphene were synthesized by calcination of nickel hydroxide and electrochemical exfoliation of graphite, respectively. Nickel oxide–graphene composites were synthesized at three levels, including 10, 20 and 30%wt of graphene by a facile hydrothermal-calcination route. The samples were characterized by XRD, FE-SEM, elemental mapping and FTIR tests, and their electrochemical performance was evaluated by electrochemical measurements including CV and EIS tests. The result of the characterization tests confirmed the successful synthesis of nickel oxide, graphene and composites. The results of the electrochemical measurements also showed that the addition of graphene to nickel oxide improved the supercapacitive properties of pure nickel oxide. Improved performance of the composites was attributed to the less aggregation of graphene sheets and their greater conductivity. Based on the results of electrochemical tests, the optimum level of graphene addition was 20%wt and NiO@G20 supercapacitor in 2.0 M KOH medium and a scan rate of 5 mV s showed a specific capacitance of 915.40 F g , energy density of 31.78 Wh kg and power density of 2.29 kW kg . Also, NiO@G20 supercapacitor was able to maintain 96.7% of its initial capacitance after 5000 cycles, which shows its high cycle stability. The high and stable activity of NiO@G20 introduces it as a promising and high-performance material for supercapacitor. [ABSTRACT FROM AUTHOR]

Physicochemical properties emerging nanomaterials possessing tungsten (W) are unique and the applications could be extended over a wide spectrum as nanocomposite electrodes for effective high voltage energy storage applications. Herewith, W doped spinel ferrite nanostructures was synthesized with facile hydrothermal strategy to get MnCo1.98W0.02O4 (MnCoW). The spectroscopic characterization studies proved spherical subunits embedded onto nanosheets formed by W doped bimetallic oxide with a crystalline phase. The resistance due to charge transfer of the electrodes was reduced which led to enhanced transfer of charge across interface of electrode and electrolyte was addressed upon W doping. Carbon based nanocomposite electrodes endowed by their unique structures and the electrochemical performance with various aqueous electrolytes were tested in an asymmetric supercapacitor application. Excellent capacitance development from 141.2 F g−1 to 203.7 F g−1 was achieved by W doping possessing an energy density of 17.9 Wh kg−1. A superior capacitance retention of 91 % was obtained from MnCoW‐based device right after 10000 cycles (charging/discharging) at 1 A g−1. The designed supercapacitor device employing MnCoW electrode exhibited better lifetime performance during lighting a LED under various angles. [ABSTRACT FROM AUTHOR]

Ti3C2Tx MXene, as a common two-dimensional material, has a wide range of applications in electrochemical energy storage. However, the surface forces of few-layer or monolayer Ti3C2Tx MXene lead to easy agglomeration, which hinders the demonstration of its performance due to the characteristics of layered materials. Herein, we report a facile method for preparing monolayer Ti3C2Tx MXene on nickel foam to achieve a self-supporting structure for supercapacitor electrodes under high electrostatic fields. Moreover, the specific capacitance varies with the deposition of different-concentration monolayer Ti3C2Tx MXene on nickel foam. As a result, Ti3C2Tx/NF has a high specific capacitance of 319 mF cm−2 at 2 mA cm−2 and an excellent long-term cycling stability of 94.4% after 7000 cycles. It was observed that the areal specific capacitance increases, whereas the mass specific capacitance decreases with the increasing loading mass. Attributable to the effect of the high electrostatic field, the self-supporting structure of the Ti3C2Tx/NF becomes denser as the concentration of the monolayer Ti3C2Tx MXene ink increases, ultimately affecting its electrochemical performance. This work provides a simple way to overcome the agglomeration problem of few-layer or monolayer MXene, then form a self-supporting electrode exhibiting excellent electrochemical performance. [ABSTRACT FROM AUTHOR]

In order to prepare biomass-derived carbon materials with high specific capacitance at a low activation temperature (≤700 °C), nanoporous carbon materials were prepared from zanthoxylum bungeanum peels and seeds via the pyrolysis and KOH-activation processes. The results show that the optimal activation temperatures are 700 °C and 600 °C for peels and seeds. Benefiting from the hierarchical pore structure (micropores, mesopores, and macropores), the abundant heteroatoms (N, S, and O) containing functional groups, and plentiful electrochemical active sites, the PAC-700 and SAC-600 derive the large capacities of ~211.0 and ~219.7 F g−1 at 1.0 A g−1 in 6 M KOH within the three-electrode configuration. Furthermore, the symmetrical supercapacitors display a high energy density of 22.9 and 22.4 Wh kg−1 at 7500 W kg−1 assembled with PAC-700 and SAC-600, along with exceptional capacitance retention of 99.1% and 93.4% over 10,000 cycles at 1.0 A g−1. More significantly, the contribution here will stimulate the extensive development of low-temperature activation processes and nanoporous carbon materials for electrochemical energy storage and beyond. [ABSTRACT FROM AUTHOR]

Two‐dimensional (2D) metal–organic frameworks (MOFs) have been a worldwide research interest due to their potential application in supercapacitors. Herein, a cobalt‐based layered MOF ([Co2(μ‐SO4)(Hppza)2(H2O)3]n, namely, SEU‐1; H2ppza=3‐(pyridin‐4‐yl)‐1H‐pyrazole‐5‐carboxylic acid) has been synthesized via a one‐step solvothermal method. Single X‐ray diffraction analysis shows that the SEU‐1 exhibits a (3,3,4)‐connected 2D structure with a Schläfli symbol of (62 ⋅ 8)(63)(64 ⋅ 8 ⋅ 10). Variable‐temperature magnetic susceptibility data display that antiferromagnetic interactions between two CoII ions exist in SEU‐1. The supercapacitive performance has been evaluated in the three‐electrode system. Its maximum specific capacitance is 145.5 F g−1 at 1 A g−1, along with the specific capacitance retention of 92.7 % at the current density of 5 A g−1 after 6000 cycles in 3 M KOH solution. These results demonstrate that SEU‐1 is a good candidate for electrode material for electrochemical energy storage. [ABSTRACT FROM AUTHOR]

Although cobalt oxides show great promise as supercapacitor electrode materials, their slow kinetics and low conductivity make them unsuitable for widespread application. We developed Ni and Cu-doped Co3O4 nanoparticles (NPs) via a simple chemical co-precipitation method without the aid of a surfactant. The samples were analyzed for their composition, function group, band gap, structure/morphology, thermal property, surface area and electrochemical property using X-ray diffraction (XRD), ICP-OES, Fourier transform infrared (FTIR) spectroscopy, Ultraviolet-visible (UV-Vis), Scanning electron microscopy (SEM), Thermogravimetric analysis (TGA) and/or Differential thermal analysis (DTA), Brunauer-Emmett-Teller (BET), and Impedance Spectroscopy (EIS), Cyclic voltammetry (CV), respectively. Notably, for the prepared sample, the addition of Cu to Co3O4 NPs results in a 11.5-fold increase in specific surface area (573.78 m2 g-1) and a decrease in charge transfer resistance. As a result, the Ni doped Co3O4 electrode exhibits a high specific capacitance of 749 Fg-1, 1.75 times greater than the pristine Co3O4 electrode's 426 F g-1. The electrode's enhanced surface area and electronic conductivity are credited with the significant improvement in electrochemical performance. The produced Ni doped Co3O4 electrode has the potential to be employed in supercapacitor systems, as the obtained findings amply demonstrated. [ABSTRACT FROM AUTHOR]

Background: Researchers are keen to reduce the over potential value through fabrication of electrocatalyst consisted of environmentally benign and inexpensive material. Supercapacitors on the other hand have gained immense attention in recent years as an energy storage device due to the high power density potential of these devices as compared to conventional batteries based storage system. Aim: The research aims to synthesize nanoscale transition metal oxides (TMO) through green route. TMO based nanomaterials have vast role in energy related applications. Materials & methods: In this study, organic compounds of A. Viridis were used as reducing and stabilizing agents in the synthesis of binary nanocomposite Sb2O3-ZrO2. The synthesized nanocomposite was characterized using xray diffraction, Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, field emission scanning electron microscopy and energy dispersive spectroscopy. The electrode material was analyzed for supercapacitor potential using cyclic voltammetry and galvanostatic charge discharge techniques. HER and OER studies were also conducted using electrochemical impedance spectroscopy and linear sweep voltammetry. The synthesized material was also tested for stability. Results & discussion: The crystal size was 15.9 nm. Optical band gap of 2.55 eV was obtained through Tauc plot. The capacitance value of 339.8 F/g at 2 mV/s and the specific capacitance of 100.6 F/g was obtained at 1 A/g. The overpotential value of 201 mV and Tafel value of 121 mV/dec was recorded for the HER, whereas the lower Tafel value of 106 mV/dec and over potential value of 383 mV was determined for OER. Electrode showed promising stability up to various cycles in case of both applications. Conclusion: The obtained results revealed the promising performance with excellent stability of fabricated electrode for super capacitor as well as water splitting studies. [ABSTRACT FROM AUTHOR]

One-step hydrothermal method is used for the simultaneous construction of three-dimensional self-supported TMA-V 2 CT x /CoV-LDH/NF composites as binder-free electrodes, which demonstrated excellent supercapacitor performance. [Display omitted] Two-dimensional (2D) MXene nanomaterials display great potential for green energy storage. However, as a result of self-stacking of MXene nanosheets and the presence of conventional binders, MXene-based nanomaterials are significantly hindered in their rate capability and cycling stability. We successfully constructed a self-supported stereo-structured composite (TMA-V 2 CT x /CoV-LDH/NF) by in-situ growing 2D cobalt vanadium layered double hydroxide (CoV-LDH) vertically on 2D few-layered V 2 CT x MXene nanosheets and interconnecting it with Ni foam (NF) with a self-supported structure to act as a binder-free electrode. In addition to inhibiting CoV-LDH aggregation, the highly conductive V 2 CT x MXene and CoV-LDH work synergistically to improve charge storage. The specific capacitance of the TMA-V 2 CT x /CoV-LDH/NF electrode is 2374 F/g (1187 C/g) at 1 A/g. At the same time, the TMA-V 2 CT x /CoV-LDH/NF exhibits excellent stability, retaining 85.3 % of its specific capacitance at 20 A/g after 10,000 cycles. In addition, the hybrid supercapacitor (HSC) is assembled based on positive electrode (TMA-V 2 CT x /CoV-LDH/NF) and negative electrode (AC), achieving the maximum energy density of 74.4 Wh kg−1 at 750.3 W kg−1. TMA-V 2 CT x /CoV-LDH/NF has potential as an electrode material for storing green energy. The research strategy provides a development prospect for the construction of novel V 2 CT x MXene-based electrode material with self-supported structures. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new 3-D bi-metal organic framework was synthesized by hydrothermal method. • After pyrolysis, binary metal oxides were prepared and applied to the anode materials of LIBs. • CeCo-700 has the highest specific capacity of 952 mAh g−1 at 100 mA g−1 after 150 cycles. Precursor method is a well-known technology for preparing certain functional materials. In this work, a novel 3d-4f bimetallic organic framework, denoted as 45MCeCo (45 M representing 4,5-imidazole dicarboxylic acid), was successfully synthesized via a hydrothermal technique. The compound thus obtained has the molecular formula of C 10 H 11 CeCoN 4 O 12. By meticulously controlling the amounts of the experimental materials, it was feasible to prepare flower-like crystals possessing identical single crystal structures and significantly larger specific surface areas. As a precursor for electrode materials, this structure underwent calcination at different temperatures to prepare Co 3 O 4 /CeO 2 composites with in situ composite heterostructures. Post-electrochemical tests revealed that CeO 2 remains unreactive across all potentials, thereby contributing to the stabilization of the electrode material structure. In contrast, Co 3 O 4 participated in redox reactions to provide a specific capacity to the sample. In addition, when comparing the performance of the electrode material under different calcination conditions, it became evident that the material exhibited optimal electrochemical performance when subjected to a temperature of 700 °C for 2 h. [ABSTRACT FROM AUTHOR]

[Display omitted] Metal-organic frameworks (MOFs) have attracted considerable attention in the field of energy storage and conversion due to their large specific surface area, regulatable pore structure and composition. However, the poor electrical conductivity and few active sites of MOFs impede their application. Herein, highly conductive MXene nanosheets are introduced to modulate the electronic conductivity and structure of rod-like Co-pyridinedicarboxylic acid (Co-PDC), and thus enhancing the electrochemical performance of MOFs. The heterostructural Co-PDC/MXene (CPM) was facily synthesized at room temperature. The as-prepared CPM-30 with 30 % MXene only requires the overpotential of 75.1 mV to achieve a current density of 10 mA cm−2 for hydrogen evolution reaction (HER), and the assembled electrolytic cell with CPM-30 and RuO 2 as cathode and anode electrodes can achieve a current density of 10 mA cm−2 at a voltage of 1.65 V. In addition, CPM-10 exhibits a high specific capacitance of 583.1 F g−1 at 0.5 A g−1 and an excellent rate performance of 41.6 % at 50 A g−1. Furthermore, the assembled asymmetric supercapacitor CPM-10//AC exhibited an energy density of 15.55 Wh kg−1 at a power density of 750 W kg−1 and excellent stability with a capacitance retention rate of 95 % after 10,000 cycles. The excellent electrochemical properties of Co-PDC / MXene are attributed to the unique structure and synergistic effect of Co-PDC and MXene. [ABSTRACT FROM AUTHOR]

Polypyrrole (PPy)-capped silver nanowire (Ag NW) nanomaterials (core–shell rod-shaped Ag NW@PPy) were synthesized using a one-port suspension polymerization technique. The thickness of the PPy layer on the 50 nm thickness/15 μm length Ag NW was effectively controlled to 10, 40, 50, and 60 nm. Thin films cast from one-dimensional conductive Ag NW@PPy formed a three-dimensional (3D) conductive porous network structure and provided excellent electrochemical performance. The 3D Ag NW@PPy network can significantly reduce the internal resistance of the electrode and maintain structural stability. As a result, a high specific capacitance of 625 F/g at a scan rate of 1 mV/s was obtained from the 3D porous Ag NW@PPy composite film. The cycling performance over a long period exceeding 10,000 cycles was also evaluated. We expect that our core–shell-structured Ag NW@PPy composites and their 3D porous structure network films can be applied as electrochemical materials for the design and manufacturing of supercapacitors and other energy storage devices. [ABSTRACT FROM AUTHOR]

Carbon materials have become a focal point in supercapacitors (SCs) due to their perfect charge–discharge behavior, relatively low cost, and excellent electrochemical stability, but the limited electrochemical activity restricts their further development. MXenes (Ti3C2Tx) combine high electrical conductivity, hydrophilicity, and abundance surface functional groups, which contribute to high energy density when compounded with carbon materials. In this work, carbon material derived from mineral water bottles is modified with cetyltrimethylammonium bromide (CTAB) that spontaneously forms into porous heterogeneous structures with Ti3C2Tx under electrostatic interactions. The carbon material hinders the reaggregation of Ti3C2Tx, while Ti3C2Tx increases the electrochemical activity on the surface of the carbon material. A hierarchical porous carbon with a large specific surface area of 1754.3 m2 g−1, promoting the electrolyte migration kinetics and high specific capacitance in 6 m KOH electrolyte (404.1 F g−1 at 1 A g−1). The symmetric SC made as‐prepared carbon electrode shows an extended voltage window (1.8 V), an optimal energy density (31.19 Wh kg−1 at a power density of 450 W kg−1) and a low capacitance decay (1% after 15 000 cycles) in 1.5 m Na2SO4. The preparation of electrode material with a unique structure provides a practical and innovative strategy for the value‐added utilization of waste plastics. [ABSTRACT FROM AUTHOR]

This investigation is motivated by an interest in multiferroic BaFe12O19 (BFO), which combines advanced ferrimagnetic and ferroelectric properties at room temperature and exhibits interesting magnetoelectric phenomena. The ferroelectric charge storage properties of BFO are limited due to high coercivity, low dielectric constant, and high dielectric losses. We report the pseudocapacitive behavior of BFO, which allows superior charge storage compared to the ferroelectric charge storage mechanism. The BFO electrodes show a remarkably high capacitance of 1.34 F cm−2 in a neutral Na2SO4 electrolyte. The charging mechanism is discussed. The capacitive behavior is linked to the beneficial effect of high-energy ball milling (HEBM) and the use of an efficient dispersant, which facilitates charge transfer. Another approach is based on the use of conductive polypyrrole (PPy) for the fabrication of PPy-BFO composites. The choice of new polyaromatic dopants with a high charge-to-mass ratio plays a crucial role in achieving a high capacitance of 4.66 F cm−2 for pure PPy electrodes. The composite PPy-BFO (50/50) electrodes show a capacitance of 3.39 F cm−2, low impedance, reduced charge transfer resistance, enhanced capacitance retention at fast charging rates, and good cyclic stability due to the beneficial effect of advanced dopants, HEBM, and synergy of the contribution of PPy and BFO. [ABSTRACT FROM AUTHOR]

Energy harvesting and energy storage are two critical aspects of supporting the energy transition and sustainability. Many studies have been conducted to achieve excellent performance devices for these two purposes. As energy‐storing devices, supercapacitors (SCs) have tremendous potential to be applied in several sectors. Some electrochemical characterizations define the performance of SCs. Electrochemical impedance spectroscopy (EIS) is one of the most powerful analyses to determine the performance of SCs. Some parameters obtained from this analysis include bulk resistance, charge‐transfer resistance, total resistance, specific capacitance, response frequency, and response time. This work provides a holistic and comprehensive review of utilizing EIS for SC characterization. Overall, researchers can benefit from this review by gaining a comprehensive understanding of the utilization of electrochemical impedance spectroscopy (EIS) for characterizing supercapacitors (SCs), enabling them to enhance SC performance and contribute to the advancement of energy harvesting and storage technologies. [ABSTRACT FROM AUTHOR]

Supercapacitors and water splitting cells have recently played a key role in offering green energy through converting renewable sources into electricity. Perovskite-type electrocatalysts such as BaTiO3, have been well-known for their ability to efficiently split water and serve as supercapacitors due to their high electrocatalytic activity. In this study, BaTiO3, Al-doped BaTiO3, Ce-doped BaTiO3, and Al-Ce co-doped BaTiO3 nanofibers were fabricated via a two-step hydrothermal method, which were then characterized and compared for their electrocatalytic performance. Based on the obtained results, Al-Ce co-doped BaTiO3 electrode exhibited a high capacitance of 224.18 Fg−1 at a scan rate of 10 mVs−1, high durability during over the 1000 CV cycles and 2000 charge–discharge cycles, proving effective energy storage properties. Additionally, the onset potentials for OER and HER processes were 11 and − 174 mV vs. RHE, respectively, demonstrating the high activity of the Al-Ce co-doped BaTiO3 electrode. Moreover, in overall water splitting, the amount of the overpotential was 0.820 mV at 10 mAcm−2, which confirmed the excellent efficiency of the electrode. Hence, the remarkable electrocatalytic performance of the Al-Ce co-doped BaTiO3 electrode make it a promising candidate for renewable energy technologies owing to its high conductivity and fast charge transfer. [ABSTRACT FROM AUTHOR]

Some drawbacks of aqueous electrolytes, such as freezing at low temperatures and extensive evaporation at high temperatures, restrict their industrial viability. This article introduces a stabilized neutral aqueous choline nitrate electrolyte with a 10 vol.% methanol additive that improves the temperature stability of the electrolyte via enhanced hydrogen bonding with the choline cation and water and maintains the good state of health of the supercapacitor cells under extreme operating conditions. The symmetric carbon/carbon supercapacitor in 5 mol/kg choline nitrate + 10 vol.% methanol (σ = 76 ms/cm at 25°C) exhibits 103 F/g at room temperature during galvanostatic charge/discharge up to 1.5 V, which decreases to 78 F/g at -40°C due to the suppressed Faradaic reactions occurring at the carbon electrode. However, under similar charge/discharge conditions, the capacitance increases to 112 F/g when the supercapacitor operates at 60°C. This capacitance increase at high temperatures is due to the Faradaic reactions related to enhanced hydrogen adsorption and desorption. The most remarkable aspect of the proposed supercapacitor is its ability to maintain capacitance and power performance during high voltage floating at 1.5 V at three tested temperatures (-40°C, 24°C, and 60°C). [ABSTRACT FROM AUTHOR]

Binary metal oxides possess unique structures and multiple oxidation states, making them highly valuable in electrochemical analysis. This study aims to determine the effect of annealing temperature on the electrochemical properties of magnesium ferrite when used as an electrode material in a neutral aqueous electrolyte. We utilized the sol–gel technique to synthesize the material and annealed it at various temperatures. Our analysis of the material using different characterization techniques reveals significant changes in its structural and electrochemical properties. We found that the material exhibited a range of phases, and higher annealing temperatures led to improved electrochemical properties. The electrochemical measurements showed reversible and redox pseudo-capacitance behavior, with the material annealed at 500 °C exhibiting the highest specific capacitance of 117 F g−1 at a current density of 0.5 A g−1. Capacitive and diffusion-controlled processes govern the total charge storage mechanism, and their contribution changes significantly as the annealing temperature varies. The capacitance retention of 500 °C annealed sample was 58% and it remained stable. This work establishes a correlation between annealing temperature on structural, morphological, and electrochemical behavior, thereby opening up avenues for tailoring them effectively. These findings can be useful in the development of future electrode materials for electrochemical applications. [ABSTRACT FROM AUTHOR]

[Display omitted] The flexible and self-healing supercapacitors (SCs) are considered to be promising smart energy storage devices. Nevertheless, the SCs integrated with flexibility, lightweight, pattern editability, self-healing capabilities and desirable electrochemical properties remain a challenge. Herein, an all-in-one self-healing SC fabricated with the free-standing hybrid film (TCMP) composed of the 2,2,6,6-tetramethylpiperidin-1-yloxy-oxidized cellulose nanofibers (TOCNs) carried carbon nanotubes (CNTs), manganese dioxide (MnO 2) and polyaniline (PANI) as the electrode, polyvinyl alcohol/sulfuric acid (PVA/H 2 SO 4) gel as the electrolyte and dynamically cross-linked cellulose nanofibers/PVA/sodium tetraborate decahydrate (CNF/PB) hydrogel as the self-healing electrode matrix is developed. The TCMP film electrodes are fabricated through a facile in-situ polymerization of MnO 2 and PANI in TOCNs-dispersed CNTs composite networks, exhibiting lightweight, high electrical conductivity, flexibility, pattern editability and excellent electrochemical properties. Benefited from the hierarchically porous structure and high mechanical properties of TOCNs, excellent electrical conductivity of CNTs and the desirable synergistic effect of pseudocapacitance induced by MnO 2 and PANI, the assembled SC with an interdigital structure demonstrated a high areal capacitance of 1108 mF cm−2 at 2 mA cm−2, large areal energy density of 153.7 μWh cm−2 at 1101.7 μW cm−2. A satisfactory bending cycle performance (capacitance retention up to 95 % after 200 bending deformations) and self-healing characteristics (∼90 % capacitance retention after 10 cut/repair cycles) are demonstrated for the TCMP-based symmetric SC, delivering a feasible strategy for electrochemical energy storage devices with excellent performance, designable patterns and desirable safe lifespan. [ABSTRACT FROM AUTHOR]

[Display omitted] • Acetate-ion-intercalated has significantly effect on electrochemical performance of NiCo-LDH. • NCLA-8 has the largest specific capacitance of 1032.2 F/g at 1 A/g. • It has demonstrating that a rate performance of 89.3% was obtained by NCLA-8. • ASCs has superior energy density of 67.7 Wh/kg at 800 W/kg. • An incredible cycle life of 82.8% after 10,000 cycles were obtained from ASCs. Enhancing the performance of layered nickel–cobalt double hydroxides (NiCo-LDH) as electrode materials for supercapacitors represents a promising strategy for optimizing energy storage systems. However, the complexity of the preparation method for electrode materials with enhanced electrochemical performance and the inherent defects of nickel–cobalt LDH remain formidable challenges. In this study, we synthesized acetate-ion-intercalated NiCo-LDH (NCLA) through a simple one-step hydrothermal method. The physical and chemical structural properties and supercapacitor characteristics of the as-prepared NCLA were systematically characterized. The results indicated that the introduction of Ac− engendered a distinctive tetragonal crystal structure in NiCo-LDH, concomitant with a reduced interlayer spacing, thus enhancing structural stability. Electrochemical measurements revealed that NCLA-8 exhibited a specific capacitance of 1032.2 F g−1 at a current density of 1 A g−1 and a high specific capacitance of 922 F g−1 at 10 A g−1, demonstrating a rate performance of 89.3%. Furthermore, NCLA-8 was used to construct the positive electrode of an asymmetric supercapacitor, while the negative electrode was composed of activated carbon. This configuration resulted in an energy density of 67.7 Wh kg−1 at a power density of 800 W kg−1. Remarkably, the asymmetric supercapacitor retained 82.8% of its initial capacitance following 3000 charge–discharge cycles at a current density of 10 A g−1. Thus, this study demonstrates the efficacy of acetate-ion intercalation in enhancing the electrochemical performance of NiCo-LDH, establishing it as a viable electrode material for supercapacitors. [ABSTRACT FROM AUTHOR]

[Display omitted] • The porous lamellar GO/Ni 2 ZnS 4 @NiCo 2 S 4 was prepared using simple ZIF-8@ZIF-9 templating method. • The core–shell structure of graphene trimetallic sulfides was synthesized for the first time. • GO/Ni 2 ZnS 4 @NiCo 2 S 4 inherits the high specific surface area of the ZIF template and the high pseudocapacitance of the sulfide. • High specific capacity of 2284F/g were achieved at the current density of 1 A/g. Metal-organic frameworks (MOFs) have emerged as promising active electrode materials in supercapacitors for its controllable porous structure and excellent physio-chemical properties. However, the poor conductivities keep it from achieving its full capacitance potential, which greatly limits its practical application. Here, a facile pathway is reported to fabricate the GO/Ni 2 ZnS 4 @NiCo 2 S 4 composite with large specific surface area and favorable electrical conductivity. Thanks to the novel tremella-like core–shell structure and high-efficient synergistic effects among multi-components, the designed GO/Ni 2 ZnS 4 @NiCo 2 S 4 electrode shows a high specific capacitance of 2284 F/g at 1 A/g. Furthermore, the asymmetric supercapacitor fabricated by coupling GO/Ni 2 ZnS 4 @NiCo 2 S 4 positive electrode with biological carbon negative electrode achieves a remarkable energy density of 120 Wh kg−1 at a power density of 750 W kg−1. [ABSTRACT FROM AUTHOR]

[Display omitted] Hierarchical nanostructures have harvested noteworthy attention lately owing to their remarkable capabilities in the fields of energy storing and transformation, catalysis, and electrical devices. We established an effort less and template-free synthetic method to create hierarchical hetero nanostructures of Zn 2 V 2 O 7 , taking into account the benefits of hierarchical nanostructures, we investigated the performance of HNs (Hierarchical Nanostructures) as electrochemical supercapacitors. Electrochemical tests were tested in a 6 M KOH solution to assess their capabilities. The Zn 2 V 2 O 7 electrode's measured specific capacitance was 750F/g at 1 A/g, with outstanding stability and an excellent retention capacity of 85 % later 5000 cycles in three- electrode electrochemical cells. Asymmetric device such as Zn 2 V 2 O 7 //AC provides a specific capacitance of 76.8F/g at 1 A/g with energy and power densities of 27.3 Wh kg−1 and 800 W kg−1 respectively. The device withstands 85 % of its initial capacity after 5000 continuous GCD cycles at 10 A/g. The outstanding performance observed clearly demonstrates the significant potential and practical utility of Zn 2 V 2 O 7 in the realm of more efficient energy storage applications. [ABSTRACT FROM AUTHOR]

The MXene-modified papers with high-uniform loading of polypyrrole and excellent conductivity have been fabricated via a multiple self-assembly and in-situ polymerization strategy, which achieves boosting areal capacitance. [Display omitted] • Multiple self-assembly and in-situ polymerization strategy is proposed tofabricate paper-based supercapacitors. • Alternate adsorption of MXene and polypyrrole on paper yields an ultra-high polypyrrole loading of 10.0 mg/cm2. • The paper-based supercapacitor shows a boosting areal capacitance of 2316 mF/cm2. Despite the intriguing features of freestanding flexible electronic devices, such as their binder-free nature and cost-effectiveness, the limited loading capacity of active material poses a challenge to achieving practical high-performance flexible electrodes. We propose a novel approach that integrates multiple self-assembly and in-situ polymerization techniques to fabricate a high-loading paper-based flexible electrode (MXene/Polypyrrole/Paper) with exceptional areal capacitance. The approach enables polypyrrole to form a porous conductive network structure on the surface of paper fiber through MXene grafting via hydrogen bonding and electrostatic interaction, resulting in an exceptionally high polypyrrole loading of 10.0 mg/cm2 and a conductivity of 2.03 S/cm. Moreover, MXene-modified polypyrrole paper exhibits a more homogeneous pore size distribution ranging from 5 to 50 μm and an increased specific surface area of 3.11 m2/g. Additionally, we have optimized in-situ polymerization cycles for paper-based supercapacitors, resulting in a remarkable areal capacitance of 2316 mF/cm2 (at 2 mA/cm2). The capacitance retention rate and conductivity rate maintain over 90 % after undergoing 100 bends.The maximum energy density and cycling stability are characterized to be 83.6 μWh/cm2 and up to 96 % retention after 10,000 cycles. These results significantly outperform those previously reported for paper-based counterparts. Overall, our work presents a facile and versatile strategy for assembling high-loading, paper-based flexible supercapacitors network architecture that can be employed in developing large-scale energy storage devices. [ABSTRACT FROM AUTHOR]

[Display omitted] Layered double hydroxide (LDH) has been attracted widespread attention in supercapacitor due to their unique layered structure and associated advantages. However, the inherent limitations of low electrical conductivity and reaction kinetics rate of LDH restrict its widespread application. Various modification techniques, such as heterojunction formation, phosphorization and introduction of phosphorus vacancies, are employed to modify LDH with the goal of improving the electrochemical performance. Preparation of composite materials using MoB MBene as conductive template and phosphorization are the effective ways for enhancing the electrical conductivity of electrode materials. MoB MBene is prepared using a modified method that combines NaOH etching and a high-temperature hydrothermal process. The presence of phosphorus vacancy is beneficial for enhancing the kinetics rate during electrode reactions. Through the synergistic effect of various modification methods, MP2 demonstrates an optimal electrochemical performance with a superior specific capacitance of 1731.19F/g (238.28 mAh g−1) at 1 A/g. It also demonstrates an impressive rate capacity of 81.28 % at 10 A/g and maintains a satisfactory capacitance retention of 88.14 % after 5000 cycles. In addition, a fabricated MP2//AC ASC device achieves an impressive energy density of 39.91 Wh kg−1 at the power density of 948.25 W kg−1 and demonstrates satisfactory cycling stability of 78.76 % after 5000 cycles. This work presents a comprehensive framework for analyzing the impact of material structure, components, and crystal phases on energy storage performance. It also examines the regulatory impact of different modification methods on energy storage mechanisms. [ABSTRACT FROM AUTHOR]

Surface microstructure modification of metal oxides also improves the electrochemical performance of metal oxide nanoparticles. The present investigation demonstrates how varying the urea molar content during the hydrothermal process altered the surfaces of MnCo2O4 nanoparticles. Successive increases of 0.1 M in urea concentration transformed the surface shape of MnCo2O4 nanoparticles from flower-like to sheet-like microstructures. Excellent electrochemical performance of MnCo2O4 nanoparticles was demonstrated in an aqueous 1 M KOH electrolyte. The improved MnCo2O4 nanoparticles have been employed to develop an asymmetric supercapacitor (ASC). The ASC device exhibits an energy density of 13 Wh/kg at a power density of 553 W/kg and a specific capacitance of 29 F g−1 at a current density of 4 mA/cm2. The MnCo2O4 nanoparticle electrode demonstrates remarkable electrocatalytic activity in both HER and OER. The MnCo2O4 electrode shows overpotential for HER and OER at 356 mV and 1.46 V, respectively. The Tafel slopes for HER and OER of the MnCo2O4 electrode are 356 mV/dec and 187 mV/dec, respectively. [ABSTRACT FROM AUTHOR]

We developeda facile method to construct flexible, freestanding three dimensional hierarchical electrodes that consist of graphene encapsulated one-dimensional conducting polyaniline (PANi)@MnO2 coaxial nanowires grown on electrospun carbon nanofibers (denoted as G-PANi@MnO2/ECNFs). A combination of XRD, SEM, and TEM techniques were used to characterize the structures of G‑PANi@MnO2/ECNFs. Electrochemical measurements confirmed that such nanostructured composites possessed higher electrochemical capacitance than that of each individual component due to synergistic effects. The G-PANi@MnO2/ECNFs electrode exhibited extremely high specific capacitance (1364.3 F/g at 0.3 A/g) and superior cycling stability (89.2% retention rate after 2000 cycles) in a 1 M Na2SO4 aqueous solution. The excellent electrochemical performance of such nanoscale architectured electrodes provides a new route to develop flexible, freestanding, and high-performance supercapacitors. [ABSTRACT FROM AUTHOR]

[Display omitted] Lignin-derived carbon materials are widely used as electrode materials for supercapacitors. However, the electrochemical performance of these materials is limited by the surface chemistry and pore structure characteristics. Herein, a novel and sustainable strategy was proposed to prepare heteroatom-doped lignin-derived carbon material (Fe-NLC) with well-developed pore size distributions and enhanced graphitization structure via a facile lignin-Fe coordination method followed by carbonization. During carbonization, Fe3+ in lignin-metal complexes evolve into nanoparticles, which act as templates to introduce porous structures in carbon materials. Also, the lignin-Fe coordination structure endows the material with a higher graphitization during carbonization, thereby improving the structural properties of the carbon materials. Due to the removal of Fe 3 O 4 template, the obtained Fe-NLC possessed reasonable pore distribution and nitrigen/oxygen (N/O) functional groups, which can improve the wettability of materials and introduce pseudocapacitance. Accordingly, Fe-NLC possesses a notable specific capacitance of 264 F/g at 0.5 A/g. Furthermore, a symmetric supercapacitor Fe-NLC//Fe-NLC with a high voltage window (1.8 V) was constructed. The symmetric supercapacitor exhibits a maximum energy density of 15.97 Wh/kg at 450 W/kg, demonstrating well application prospects. This paper proposes a novel approach for preparing carbon materials via lignin-metal coordination to provide an alternative way to explore sustainable and low-cost energy storage materials. [ABSTRACT FROM AUTHOR]

Polyindole (PIN) has been one of the rising promising conducting polymers of this decade, attracting researchers' attention worldwide. This can be attributed to better redox activity and physicochemical stability. Several techniques had reported synthesis of PIN in organic and aqueous media. However, it has been always reported as difficult. Challenges such as mixed morphology, irregular particle size and undesired agglomeration are among several outcomes' researchers face. Hence, for the first time we present hydrotopically engineered chemical oxidative polymerisation of indole in the presence of Vanadium selenide (VS) in aqueous media. A hydrotrope is a compound that enhances the aqueous solubility of organic compound. The resulting nanocomposite was comprised of decorated polyindole over self-assembled 1D vanadium selenide, giving a 3D sheet like structure, as evident from FESEM studies. The results also highlighted uniform decoration of PIN over the background of VS. Besides, the physicochemical interaction between PIN and VS had been validated using Fourier transform infrared (FTIR) and XRD analysis. Furthermore, electrochemical studies through cyclic voltammetry, galvanic charging discharging techniques for the nanocomposite revealed improved specific capacitance of PV (w.r.t VS) as evidenced from the higher voltametric output current than VS. Electrochemical impedance also corroborated the superior charge transfer at lower frequencies, suggesting the real time applications of the nanocomposite. Lastly, to compliment the electrochemical performance, the nano composite was also used in fabrication of asymmetric super capacitor, which was used to illuminate LED and power a digital stopwatch to augment the conductivity and real time charge storage ability of the as synthesised nanocomposite. To the best of our knowledge, synthesis of PV nano composite using hydrotrope – tetra n-octyl ammonium bromide in aqueous medium can be a promising electrode material for fabrication of super capacitor, resulting in a synergistic enhancement of vanadium selenide using PIN. [ABSTRACT FROM AUTHOR]

Two-dimensional transition metal carbides/nitrides (MXenes) are emerging members of the two-dimensional material family, obtained by removing the A layer of the MAX phase through methods such as liquid-phase etching. This article summarizes the structure and properties of MXenes, as well as several preparation methods, including etching with hydrofluoric acid and fluoride salts, alkali-based etching, electrochemical etching, Lewis acid molten salt etching, and direct synthesis. Due to their unique two-dimensional structure and surface chemistry, MXenes exhibit good metallic conductivity, hydrophilicity, excellent flexibility, and ion intercalation properties, showing great potential in the research and application of supercapacitors and attracting widespread attention. The combination of MXene with other types of materials, including polymers, metal hydroxides, metal oxides, and carbon materials, takes advantage of composites to improve energy storage performance and shows great potential in the research and application of supercapacitors. This article provides a detailed summary of MXene composite materials and capacitor performance and introduces the research progress of MXene materials in the field of supercapacitor energy storage applications, aiming to provide references for the preparation of high-performance MXene supercapacitor electrode materials. [ABSTRACT FROM AUTHOR]

In the last ten years, there has been a significant increase in supercapacitor research in energy storage systems. A supercapacitor is an electrochemical capacitor made up of two electrodes, a separator, and a solution of electrolyte. The supercapacitor is distinguished from capacitors and li-ion batteries by its high power density and long cycle counts. This situation provides a broad application area for supercapacitors derived from consumables (cameras, computer equipment, etc.) in the defense industry (laser guns). Furthermore, electric and hybrid vehicle technologies are being developed gradually. The use of supercapacitors in these vehicles improves battery performance. The working principles of supercapacitors are examined in depth in this study. Furthermore, current electrochemical performance measurements of electrodes (graphene, activated carbon, carbon nanotubes, metal oxides, and conductive polymers) formed in accordance with supercapacitor types were investigated. According to this article, the studies will contribute to the development of superior-performance supercapacitors and their applications. [ABSTRACT FROM AUTHOR]

A symmetric supercapacitor device with high electrochemical performance was assembled using the TC- P -3 hybrid film electrode. [Display omitted] Robust, conductive and flexible electrode materials have been the focus of attention in portable, wearable electronics. However, it is still a significant challenge to achieve synergistic development of multiple properties simultaneously. Herein, we propose a combination of microscale design and nanostructures strategy to prepare MXene/cellulose nanofiber-poly (3,4-ethylenedioxythiphoenes):polystyrene sulfonate (Ti 3 C 2 T x /CNF-PEDOT:PSS, TC-P) hybrid film by a simple in-situ polymerization and vacuum filtration process. CNF serves as the supporting skeleton of PEDOT:PSS, effectively mitigating its self-aggregation and structural deformation due to the expansion/contraction of the polymer network. And the CNF-PEDOT:PSS composite is capable to open up the interlayer space of Ti 3 C 2 T x , which reduces the self-stacking of Ti 3 C 2 T x nanosheets. The strong interactions among the three components enable the hybrid film electrode to possess both flexibility and high electrochemical properties. As a result, the film electrode exhibits a remarkable tensile strength of 77.4 MPa and an excellent conductivity of 162.5 S cm−1, as well as an outstanding areal specific capacitance of 896 mF cm−2 at 4 mA cm−2. Moreover, the assembled symmetric supercapacitor (SSC) device displays a large areal energy density of 62 µWh cm−2 at a power density of 800 µW cm−2 and demonstrates a long cycle life with 85.1 % capacitance retention after 10,000 GCD cycles. This study provides an effective strategy to balance mechanical flexibility and electrochemical properties, providing an inspiration to prepare flexible electrodes that are widely applied in a new generation of portable, wearable electronics. [ABSTRACT FROM AUTHOR]

[Display omitted] Supercapacitors have the advantages of fast charging and discharging speeds, high power density, long cycle life, and wide operating temperature range. They are widely used in portable electronic equipment, rail transit, industry, military, aerospace, and other fields. The design and preparation of low-cost, high-performance electrode materials still pose a bottleneck that hinders the development of supercapacitors. In this paper, coal was used as the raw material, and the coal-based porous carbon electrode material was constructed using the iodine intercalation-assisted activation method and used for supercapacitors. The CK-700 electrode exhibits excellent charge storage performance in a 6 M potassium hydroxide (KOH) electrolyte, with a maximum specific capacitance of 350 F/g at a current density of 0.5 A/g. In addition, it has an excellent rate performance (310 F/g at 1 A/g) and cycle stability (capacitance retention up to 91.7 % after 30000 cycles). This work provides a method for realizing high-quality, high-yield and low-cost preparation of coal-based porous carbon, and an idea for improving the performance of supercapacitors. [ABSTRACT FROM AUTHOR]

The primary goal for the development of energy-storage devices is to find affordable ways to increase their efficiency, activity, and stability. In this regard, transition metal oxide mainly MoO 3 enhances the electrochemical properties of the material due to various oxidation states. On the other hand, carbonaceous materials, such as reduced graphene oxide, provide a large surface area that increases the conductivity of nanomaterials. In this work, we have synthesized pristine and codoped MoO 3 material using the co-precipitation route. While the r-GO based composite was prepared by a simple sonication approach. The prepared composite material showed a higher specific capacitance of 987 F/g than the pristine and codoped material. The BAMO@r-GO discharges after 346 s which was the higher time of discharge than that of pure and codoped material. Moreover, the obtained results from EIS measurement confirmed that the composite material showed less resistance than all other synthesized materials. The synergistic effect between the r-GO and BAMO materials is the reason for the higher supercapacitor performances of BAMO@r-GO. Based on these results, the fabricated BAMO@r-GO material can be effectively utilized as an electrode material in electrochemically powered energy storage devices. [ABSTRACT FROM AUTHOR]

In this research, manganese cobaltite (MCO) nanoparticles with different morphologies were synthesized by a simple hydrothermal method with excellent electrochemical properties. To investigate the physical features of prepared samples, XRD analysis was used to study the crystalline structure. The SEM and TEM proved that the morphology of synthesized materials formed as flake and nanoplane structures. The electrode of samples was prepared using the hydrothermal method and the electrochemical properties of samples were investigated by cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), electrochemical impedance spectroscopy (EIS) and cyclic stability analysis. Results showed that the flake structures of nanoparticles revealed the highest capacitance of 1971.98 F ⋅ g − 1 at 0.5 Ag − 1 as well as longer stability compared to the others with the nanoplane structure. The high cyclic stability of 91.47% after 5000 cycles introduces this electrode as a durable and promising electrode for use in energy storage devices. [ABSTRACT FROM AUTHOR]

As the precursor of 2D i -MXene, i -MAX phase appeals lots of exertions on the improvement of its chemical diversity, among which alloying is an effective strategy. Herein, we report on the synthesis of the M-alloyed i -MAX phase (Mo 0.75 M 0.25) 4/3 Er 2/3 GaC (M = Ti, V, Nb, Ta, W). Structure analysis identifies all of them as Cmcm orthorhombic. The corresponding M-alloyed i -MXene, (Mo 0.75 M 0.25) 1.33 CT z (M = Ti, V, Nb, Ta, W), was synthesized by HF etching and shows potential as an electrode for supercapacitors due to its improved charge storage performance and cyclic stability. A volumetric capacitance of 431.7 F g−1 was delivered at the scan rate of 2 mV s−1 for (Mo 0 · 75 V 0.25) 1.33 CT z , and a 94.8% capacitance was retained after 10,000 charge/discharge cycles for (Mo 0 · 75 W 0.25) 1.33 CT z. Modelling was performed to better understand the mechanism improving the electrochemical capacitance and to clarify the i-MXene alloying process. The alloying strategy shows a novel and simple way to control i-MXene's surface termination, which will make it facilitate to use in applications like high-performance supercapacitors. [ABSTRACT FROM AUTHOR]

In recent years, notable headway has been made in augmenting supercapacitor functioning through employment of pioneering components, exceptional nanostructures and additional investigation of electrolytes. Nonetheless, achieving superior performance with straightforward techniques remains a significant hurdle. In order to surmount this, an experimental three-dimensional nanospherical pore structure (TPB-20@Ni(OH)2) was designed and prepared. TPB-1 was obtained through carbonisation and activation. TPB-20@Ni(OH)2 nanoparticles were synthesized using TPB-1 as the carbon source and nickel chloride hexahydrate as the nickel source. Furthermore, the TPB-20@Ni(OH)2//AC supercapacitor displayed an impressive energy density of 22.1 Wh kg−1. The TPB-20@Ni(OH)2 composites exhibited a specific capacity of 978 F−1, which is noteworthy. The exceptional output exhibited by the TPB-20@Ni(OH)2 composite derives from its innovative structure, presenting an extensive specific surface area of 237.4 m2 g−1 and porosity of roughly 4.0 nm. Following 20 000 cycles (at a current density of 1 A g−1), asymmetric supercapacitors assembled from TPB-20@Ni(OH)2//AC retained 80.0% of its initial specific electrostatic capacity, indicating superior electrochemical stability and high electrochemical reversibility. [ABSTRACT FROM AUTHOR]

Metal halide perovskites (MHPs) are extremely promising materials for energy storage applications. Among them, two‐dimensional (2D) halide perovskites attract much attention for supercapacitor applications because of exciting properties such as electronic confinement, structural flexibility, attractive performance and stability. On the other hand, owing to its low exciton binding energy and long‐range carrier transport nature, three‐dimensional (3D) halide perovskites have been employed as one of the most promising supercapacitor materials. These materials have become one of the highly promising mixed electronic‐ionic material for efficient energy storage devices. 2D and 3D MHPs have distinctive physicochemical and electrochemical characteristics, and capacity to create hetero‐structures to strengthen their electrochemical capabilities. Thus, it is important to understand synthesis, properties and various electrochemical aspects of MHPs and their super‐capacitive behaviors. This review article focuses on the extensive overview of the recent developments of MHPs which have demonstrated exciting possibilities as supercapacitor materials but relatively less explored till now. Our review article comprises of synthesis processes, opto‐electronic properties, mechanism, supercapacitor performances, challenges and opportunities in brief. This review thus thoroughly discusses the importance and intriguing aspect of 2D and 3D halide perovskites as supercapacitor materials for their futuristic energy storage applications. [ABSTRACT FROM AUTHOR]

With the rapid advances in the Internet of Things, it is possible to construct a self-charging power system integrating a triboelectric nanogenerator (TENG) and supercapacitor (SC), which represents an excellent tool for simultaneous conversion and storage of distributed environmental energy. In particular, the well-researched Ti3C2T x MXene materials for triboelectric nanogeneration lack high and stable power density, mainly due to the charge dissipation effect on their surface. Herein, the effectiveness of MXenes is enhanced by encrusting TiO2 on the inner and outer surfaces via a hydrothermal method. TiO2, which has inherent dielectric properties, could serve the dual function of electron trapping/blocking and surface polarization, mitigating the diffusion and drifting of surficial tribo-charges and thus increasing output TENG performance. An integrated TENG based on MXene/TiO2 composites with a TiO2 concentration of 3 mM has a higher output voltage than a pristine MXene-based TENG (110 V, a 1.83-fold increase) and achieves a maximum instantaneous power density of ∼1440 mW m−2. TiO2 is also conductive to pseudo-faradaic reactions, and the integrated MXene/TiO2 based symmetric SC exhibits an enhanced specific capacitance of 231.08 F g−1 at 1 A g−1, which is 4.52 times that of pristine MXene, with a maximum energy density of 12.74 W h kg−1 at a power density of 483.06 W kg−1. Finally, utilizing polyimide sheets as substrates, the flexible self-charging power system was integrated: the TENG charges the SC up to 0.8 V with a charging/discharging time of 37 s/40 s, showing great promise for the demands of flexible and self-powered electronics. [ABSTRACT FROM AUTHOR]

Flexible supercapacitors (FSCs) with high electrochemical and mechanical performance are inevitably necessary for the fabrication of integrated wearable systems. Conducting polymers with intrinsic conductivity and flexibility are ideal active materials for FSCs. However, they suffer from poor cycling stability due to huge volume variations during operation cycles. Two-dimensional (2D) materials play a critical role in FSCs, but restacking and aggregation limit their practical application. Nanocomposites of conducting polymers and 2D materials can mitigate the above-mentioned drawbacks. This review presents the recent progress of those nanocomposites for FSCs. It aims to provide insights into the assembling strategies of the macroscopic structures of those nanocomposites, such as 1D fibers, 2D films, and 3D aerogels/hydrogels, as well as the fabrication methods to convert these macroscopic structures to FSCs with different device configurations. The practical applications of FSCs based on those nanocomposites in integrated self-powered sensing systems and future perspectives are also discussed. [ABSTRACT FROM AUTHOR]

[Display omitted] • The chitin derived hydrochar at 300 °C has a high N content (10.7 wt%) and thermal stability. • N, O co-doped hierarchical porous carbon with high specific surface area and abundant N, O heteroatoms was successfully prepared. • Abundant N, O heteroatoms contribute to additional pseudocapacitance. • The assembled symmetric supercapacitors present an ultrahigh energy density of 30.8 Wh kg−1 at 180 W kg−1. Rational design of hierarchical porous architecture with abundant pseudocapacitive sites is highly desirable for carbon electrode materials. However, the lengthy production process and high economic input limit its broader application. Herein, we successfully prepared N, O co-doped hierarchical porous carbon (NOHC) through hydrothermal carbonization (HTC) of chitin biomass with the assist of NH 4 Cl and subsequent carbonization with NaNH 2. The optimal NOHC600 exhibits a remarkable hierarchical porous structure and an ultrahigh specific surface area (SSA) of 2555 m2 g−1. Furthermore, it showcases a significant content of N, O co-doping, thereby providing abundant defects and additional active sites for ion adsorption. The aforementioned characteristics ensure outstanding capacitance performance of NOHC600. In the three-electrode system, NOHC600 exhibits a remarkable specific capacitance of up to 455 F g−1 at a current density of 0.5 A g-1. The symmetric supercapacitors (SCs) based on NOHC600 achieve an impressive energy density of 30.4 Wh kg−1 at a power density of 180 W kg−1. Moreover, the all-solid-state NOHC600 microsupercapacitors (MSCs) demonstrate an exceptional areal capacitance of 78.2 mF cm−2 and an areal energy density of up to 10.8 μWh cm−2. Accordingly, this facile and scalable strategy shows a great potential for producing high-heteroatom-doped porous carbon materials from chitin biomass, which can be applied in practical energy-related applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hydrothermal and sol-gel method were combined to prepare carbon microspheres. • Carbon microspheres with multi-layer dendritic hollow structure, high specific surface area and abundant micropores were successfully prepared. • Excellent cycle stability and great specific capacitance were obtained by the supercapacitor prepared from the carbon microspheres. The electrochemical properties of corn starch (CS)-based hydrothermal carbon microsphere (CMS) electrode materials for supercapacitor are closely related to their structures. Herein, cetyltrimethyl ammonium bromide (CTAB) was used as a soft template to form the corn starch (CS)-based carbon microspheres with radial hollow structure in the inner and middle layers by hydrothermal and sol-gel method. Due to the introduction of multi-layer hollow structure of carbon microsphere, more micropores were produced during CO 2 activation, which increased the specific surface area and improved the capacitance performance. Compared to commercial activated carbon, the four different morphologies of corn starch CMS had better electrochemical performances. Consequently, the proposed CO 2 –(CTAB)-CS-CS exhibits a high discharge specific capacitance of 242.5F/g at 1 A/g in three-electrode system with 6 M KOH electrolyte, better than commercial activated carbon with 208.5F/g. Moreover, excellent stability is achieved for CO 2 –(CTAB)-CS-CS with approximately 97.14 % retention of the initial specific capacitance value after 10,000 cycles at a current density of 2 A/g, while the commercial activated carbon has 86.96 % retention. This implies that the corn starch-based multilayer hollow CMS could be a promising electrode material for high-performance supercapacitors. [ABSTRACT FROM AUTHOR]

Aqueous supercapacitors have occupied a significant position among various types of stationary energy storage equipment, while their widespread application is hindered by the relatively low energy density. Herein, N/F co-doped carbon materials activated by manganese clusters (NCM) are constructed by the straightforward experimental routine. Benefiting from the elevated conductivity structure at the microscopic level, the optimized NCM-0.5 electrodes exhibited a remarkable specific capacitance of 653 F g−1 at 0.4 A g−1 and exceptional cycling stability (97.39% capacity retention even after 40,000 cycles at the scanning rate of 100 mV s−1) in a neutral 5 M LiCl electrolyte. Moreover, we assembled an asymmetric device pairing with a VOx anode (NCM-0.5//VOx), which delivered a durable life span of 95% capacity retention over 30,000 cycles and an impressive energy density of 77.9 Wh kg−1. This study provides inspiration for transition metal element doping engineering in high-energy storage equipment. [ABSTRACT FROM AUTHOR]