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Electrochemical Double Layer Capacitors (EDLCs) with ionic liquid electrolytes outperform conventional ones using aqueous and organic electrolytes in energy density and safety. However, understanding the electrochemical behaviors of ionic liquid electrolytes under compressive/tensile strain is essential for the design of flexible EDLCs as well as normal EDLCs, which are subject to external forces during assembly. Despite many experimental studies, the compression/stretching effects on the performance of ionic liquid EDLCs remain inconclusive and controversial. In addition, there is hardly any evidence of prior theoretical work done in this area, which makes the literature on this topic scarce. Herein, for the first time, we developed an atomistic model to study the processes underlying the electrochemical behaviors of ionic liquids in an EDLC under strain. Constant potential non-equilibrium molecular dynamics simulations are conducted for EMIM BF4 placed between two graphene walls as electrodes. Compared to zero strain, low compression of the EDLC resulted in compromised performance as the electrode charge density dropped by 29%, and the performance reduction deteriorated significantly with a further increase in compression. In contrast, stretching is found to enhance the performance by increasing the charge storage in the electrodes by 7%. The performance changes with compression and stretching are due to changes in the double-layer structure. In addition, an increase in the value of the applied potential during the application of strain leads to capacity retention with compression revealed by the newly performed simulations. [ABSTRACT FROM AUTHOR]

Aqueous Zn-ion hybrid supercapacitors (AZHSCs) combining the advantages of high‐energy batteries and high‐power supercapacitors see a bright future, but they still suffer from the poor capacity of carbonic cathodes. Herein, a functionalized porous carbon cloth (denoted as FPCC) electrode is demonstrated based on commercial carbon cloth (denoted as CC) tuning by structural and surface engineering. The constructed exfoliated porous carbon layer and the negatively charged functionalized interface not only increase the electrical double layer capacitance but also favor the chemical adsorption of Zn2+ to obtain additional pseudocapacitance. Consequently, the FPCC electrode delivers a high capacity of 0.16 mAh cm−2 at 4 mA cm−2, which is 923.8 times higher than CC, and a long cycle life (85.0% capacity retention after 30 000 cycles). More importantly, the Zn//FPCC AZHSC possesses an impressive energy density (3.3 mWh cm−3) and power density (240 mW cm−3), superior to many advanced batteries and supercapacitors. The quasi-solid-state device is also assembled as a demo. This modification strategy may provide new opportunities for high-performance AZHSCs. [ABSTRACT FROM AUTHOR]

Due to the importance of supercapacitors in electronic storage devices, improving their efficiency is one of the topics that has attracted the attention of many researchers. Choosing the proper electrolyte for supercapacitors is one of the most significant factors affecting supercapacitors' performance. In the present paper, we compare liquid electrolytes (ionic liquid electrolytes) and solid electrolytes (polymer electrolytes) by molecular dynamics simulation to summarize their pros and cons. We consider polymer electrolytes in linear and network configurations. The results show that although ionic liquid-based supercapacitors have a larger differential capacitance since they have a smaller operation voltage, the energy stored is less than polymer electrolyte-based supercapacitors. Also, our investigations indicate that polymer electrolyte-based supercapacitors have more mechanical stability. Therefore, they can be considered a very suitable alternative to liquid electrolyte-based supercapacitors since they do not have known liquid electrolyte problems and display better performance. [ABSTRACT FROM AUTHOR]

The shortage of natural resources due to the progression of the human population and environmental pollution has become crucial concern topics to resolve. One of the best ways to resolve this is to develop renewable energy-based storage systems. Supercapacitors are emerging as promising storage systems via providing rapid charging/discharging and high power delivery, but there is a need to explore low-cost, environment-friendly, non-toxic, abundant, and biodegradable electrode materials for supercapacitors. In this regard, biopolymers are observed to be popular for storage applications as they are of high porosity, cost-effective, easily available, low-weight, and environment friendly and have biodegradability properties. The biopolymer-based electrode has a desirable morphology and high surface area and exhibits admirable electrochemical properties. The focus of this report is to highlight (i) the inclusive details of supercapacitors and their types along with strategies to improve their electrochemical performance, (ii) biopolymers and their types used for supercapacitor applications, (iii) various synthesis routes that could be adopted for designing electrode materials based on biopolymers for supercapacitors, and (iv) challenges and future scope of biopolymers as the electrode material in supercapacitor applications. The detailed study here in this report is found to be a topic of interest for the scientific community to fabricate and prepare low-cost, eco-friendly, high electrochemical performance exhibiting electrode materials for supercapacitor applications. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) have been widely explored and applied in many fields. However, the poor electrical conductivity of many traditional MOFs greatly limits their application in electrochemistry, especially in energy storage. In this study, a typical cMOF (Ni-HHTP, HHTP = 2,3,6,7,10,11-hexahydroxytriphenylene) was compounded with MXene nanosheets and a series of composites, namely MXene@Ni-HHTP-x (x = 1–8), were obtained. As a result, when MXene@Ni-HHTP-2 was assembled as a positive electrode material in an asymmetric supercapacitor, it achieved a specific capacitance of 416.6 F g−1 at 0.5 A g−1, manifesting a good performance in energy storage. [ABSTRACT FROM AUTHOR]

Highlights The urgent need for sustainable energy storage solutions has spurred research on high‐performance and cost‐effective energy storage technologies. Supercapacitors (SCs) show great potential due to their capacity to provide significant capacitance, energy and power density. This study focused on the enhancement of electrically conductive reduced Graphene Oxide (rGO) reinforced with polyaniline (PANI) composites to fabricate the supercapacitors. Various characterization techniques, including SEM, EDAX, Raman spectroscopy, FTIR, PXRD, TGA, BET, and CV were employed for the examination of the materials. The findings demonstrate that the rGO/PANI composite displayed nanostructured layers characterized by flaky leaf‐like structures, a trigonal crystal system, and a notable specific capacitance of 410 Fg−1, along with capacitance retention rate of 85 after completion of 1000 cycles. This composite showcases outstanding electrochemical performance leads to the promising material to use in SCs manufacturing. Electrode showed pseudocapacitive behavior, capacitance of 392 F/g. PXRD pattern confirmed presence of benzenoid and quinonoid groups. BET analysis showed surface area of 16.850 m2/g, porous nature indicated. Electrode displayed good reversibility, with a‐b value of 0.6. [ABSTRACT FROM AUTHOR]

The electrochemical performance of supercapacitors drops precipitously at extreme low temperatures due to a multitude of reasons, which includes electrolyte freezing, sluggish ion transport in the electrode and electrolyte, and high charge transfer resistance at electrode–electrolyte interfaces. To address high interface resistance, a new supercapacitor architecture is reported, in which MXene/carbon nanotube electrodes with vertically aligned channels are synthesized to reduce tortuosity and maximize the electrode–electrolyte contact area. These electrodes are fabricated using a directional‐freezing strategy, generating direct and fast ion transport pathways. Further, a freeze‐resistant electrolyte which shows high ionic conductivity is synthesized by designing a double‐crosslinked polymer network in a binary solvent consisting of ionic liquid and water, which exhibits an ultralow freezing temperature of −54 °C. An all‐in‐one supercapacitor is assembled by an integrated polymerization strategy to minimize interfacial resistances. The resulting device delivers a specific capacitance of 231 F g−1 at 2 mV s−1 and a maximum energy density of 10.17 Wh kg−1, while maintaining a capacitance retention of 92%, even at an extreme low temperature of −50 °C. The supercapacitor architecture developed in this study, demonstrates the feasibility of electrochemical energy storage at extreme low temperatures. [ABSTRACT FROM AUTHOR]

Self‐charging power systems (SCPSs) are envisioned as promising solutions for emerging electronics to mitigate the increasing global concern about battery waste. However, present SCPSs suffer from large form factors, unscalable fabrication, and material complexity. Herein, a type of highly stable, eco‐friendly conductive inks based on poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) are developed for direct ink writing of multiple components in the SCPSs, including electrodes for miniaturized spacer‐free triboelectric nanogenerators (TENGs) and microsupercapacitors (MSCs), and interconnects. The principle of "one ink, multiple functions" enables to almost fully print the entire SCPSs on the same paper substrate in a monolithic manner without post‐integration. The monolithic fabrication significantly improves the upscaling capability for manufacturing and reduces the form factor of the entire SCPSs (a small footprint area of ≈2 cm × 3 cm and thickness of ≈1 mm). After pressing/releasing the TENGs for ≈79000 cycles, the 3‐cell series‐connected MSC array can be charged to 1.6 V while the 6‐cell array to 3.0 V. On‐paper SCPSs are promising to serve as lightweight, thin, sustainable, and low‐cost power supplies. [ABSTRACT FROM AUTHOR]

[Display omitted] • Developing surface structuring of Al current collectors for battery application. • Developing crack formation on the electrodes to enhance electrolyte diffusion. • Improving electrode adhesion using structured Al current collectors. • Crack formation enabling fast charging-rates and battery cycle life. Today's society and economy demand high-performance energy storage systems with large battery capacities and super-fast charging. However, a common problematic consequence is the delamination of the mass loading (including, active materials, binder and conductive carbon) from the current collector at high C-rates and also after certain cycle tests. In this work, surface structuring of aluminum (Al) foils (as a current collector) is developed to overcome the aforementioned delamination process for sulfur (S)/carbon composite cathodes of Li-S batteries (LSBs). The structuring process allows a mechanical interlocking of the loaded mass with the structured current collector, thus increasing its electrode adhesion and its general stability. Through directed crack formation within the mass loading, this also allows an enhanced electrolyte wetting in deeper layers, which in turn improves ion transport at increased areal loadings. Moreover, the interfacial resistance of this composite is reduced leading to an improved battery performance. In addition, surface structuring improves the wettability of water-based pastes, eliminating the need for additional primer coatings and simplifying the electrode fabrication process. Compared to the cells made with untreated current collectors, the cells made with structured current collectors significantly improved rate capability and cycling stability with a capacity of over 1000 mAh g−1. At the same time, the concept of mechanical interlocking offers the potential of transfer to other battery and supercapacitor electrodes. [ABSTRACT FROM AUTHOR]

The interpenetrating polymer networks PVA-SA-PPy hydrogels were prepared by the freeze-thawing and in-situ polymerization method. The PVA network and SA network formed interpenetrating networks through hydrogen bonding and physical entanglement, which boosted the mechanical properties and ion diffusion characteristics. [Display omitted] Flexible supercapacitors (FSCs) have attracted much attention due to their strong mechanical flexibility, wearability and portability, which greatly rely on the employed flexible electrodes. The conductive polymer hydrogels with excellent flexibility, processability and capacitive performance are one of the most promising candidates, which are still limited by their poor mechanical properties. Constructing robust interpenetrating polymer networks (IPN) is an effective approach to promote their mechanical properties. Herein, interpenetrating polyvinyl alcohol (PVA)-sodium alginate (SA)-polypyrrole (PPy) hydrogels are prepared by the freeze–thaw and in-situ polymerization method. The IPN structure composed of PVA and SA not only enhances the mechanical properties of hydrogels, but also provides substantial active sites for electrochemical reactions. Moreover, the hydrogen-bonding interaction between different components in the PVA-SA-PPy hydrogel boosts the charge/ion transfer. The optimal PVA-SA-PPy hydrogels show an elongation at break of 380 %, a tensile strength of 1.5 MPa, and a specific capacitance of 2646 mF cm−2 at 2 mA cm−2. The symmetric PVA-SA-PPy FSCs show an energy density of 96.7 μWh cm−2 at a power density of 999.9 μW cm−2, and the capacitance retention is 66.3 % after 10,000 cycles. These exceptional mechanical and electrochemical properties make the PVA-SA-PPy hydrogels a promising candidate for FSCs. [ABSTRACT FROM AUTHOR]

[Display omitted] • Use of a university two-step strategy to construct 3D VO 2 /CNT@PANI with core–shell architecture. • Taking full advantage of the synergistic effect, the optimal VO 2 /CNT@PANI exhibits superior electrochemical performances. • Fabrication of a full-printable in-planar symmetric supercapacitor with a remarkable areal energy density and cycling life. • Great potential application prospects in the field of portable/wearable electronics. As a progressive electronic energy storage device, the flexible supercapacitor holds tremendous promise for powering wearable/portable electronic products. Of various pseudocapacitor materials, vanadium dioxide (VO 2) has garnered extensive attention due to its impressive theoretical capacitance. However, the challenges of inferior cycling life and lower energy density to be addressed. Herein, we prepare VO 2 nanorods with winding carbon nanotubes (CNT) via a facile solvothermal route, followed by in situ polymerization of polyaniline (PANI) shell. Taking full advantage of the synergistic effect, the VO 2 /CNT@PANI composite delivers a high specific capacitance of 354.2F/g at 0.5 A/g and a long cycling life of ∼ 88.2 % over 5000 cycles resulting from the enhanced conductivity of CNT and stabilization of PANI shell. By screen printing the formulated inks with outstanding rheological behaviours, we manufacture an in-planar VO 2 /CNT@PANI symmetric supercapacitor (VO 2 /CNT@PANI SSC) device featuring an orderly arrangement structure. This device yields a remarkable areal energy density of 99.57 μWh/cm2 at a power density of 387.5 μW/cm2 while retaining approximately ∼ 87.6 % of its initial capacitance after prolonged use. Furthermore, we successfully powered a portable game machine for more than 2 min using two SSCs connected in series with ease. Therefore, this work presents a universal strategy that utilises combination and coating to boost electrochemical performance for flexible high-performance supercapacitors. [ABSTRACT FROM AUTHOR]

CoNi LDH nanostructures with large specific surface areas were prepared through a facile sonochemical approach in the solutions with different pH values. The CoNi LDH exhibited battery-type electrochemical response with the highest capacity of 740.8C/g at 1 A/g in 2 M of KOH electrolyte. The assembled CoNi LDH//AC hybrid supercapacitor delivered the highest energy density of 35.6 W h kg−1 at the power density of 781.1 W kg−1. [Display omitted] • CoNi LDH nanostructures with large surface area were sonochemically prepared. • A high specific capacity of 740.8C/g at 1 A/g was delivered. • Just a little capacity decay over 5000 cycles at a high current density of 8 A/g. • The HSC device delivered an energy density of 35.6 W h kg−1 at 781.1 W kg−1. Fabricating battery-type electrode materials with large specific surface area and mesopores is an efficient method for enhancing the electrochemical performance of supercapacitors. This method may provide more active sites for Faradic reactions and shorten the ion-diffusion paths. In this study, the CoNi layered double hydroxides (LDHs) with the morphology of nanoflowers and nanoflakes were prepared in solutions with pH values of 7.5 (CoNi LDH-7.5) and 8.5 (CoNi LDH-8.5) via a simple sonochemical approach. These CoNi LDHs possessed large specific surface areas and favourable electrochemical properties. The CoNi LDH-7.5 delivered a specific capacity of 740.8C/g at a current density of 1 A/g, surpassing CoNi LDH-8.5 with 668.1C/g. The hybrid supercapacitor (HSC) was assembled with activated carbon as the anode and CoNi LDH as the cathode to assess its practical application potential in the field of electrochemical energy storage. The CoNi LDH-7.5//AC HSC achieved the highest energy density of 35.6 W h kg−1 at a power density of 781.1 W kg−1. In addition, both HSCs exhibited little capacity decay over 5,000 cycles at a high current load of 8 A/g. These electrochemical properties of CoNi LDHs make them promising candidates for battery-type electrode materials. The current sonochemical method is simple and can be applied to the preparation of other LDHs-based electrode materials with favourable electrochemical performance. [ABSTRACT FROM AUTHOR]

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

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]

We report the electrochemical performance of wrinkled/washable graphene-based supercapacitors (SCs). Sustainable graphene electrodes were fabricated by printing graphene microplates on recycled plastics (taken from wasted chip-packets), which provided flexibility to the SCs. The devices made with only graphene electrodes had an energy-density/specific-capacitance of 8.8 Wh kg−1/99.1 F g−1. To enhance the electrochemical properties of the SCs, a mixture of La 0.2 Gd 1.8 Zr 2 O 7 (LGZ) and La 0.7 Sr 0.3 MnO 3 (LSM) perovskites (redox materials) were added on their electrodes. After this, the energy-density/capacitance was enhanced to 53.1 Wh kg−1/596.90 F g−1, that is, an improvement of 503/502%, respectively. Subsequently, the solid state SCs were completely rolled or wrinkled, in consequence, the capacitance decreased by 12.1 and 35.6%, respectively. Even more, the SCs were immersed in water or subjected to washing/drying cycles using a washing-machine and the capacitance barely decreased by ⁓14.2%. Additionally, the thickness of the SC electrodes was varied in the range of 65–400 μm and obtained the maximum capacitance for a thickness of 330 μm. Overall, we demonstrated that incorporating the LGZ/LSM perovskite on the SC electrodes provided extra redox centers, which incremented the capacitance of the devices. The SCs reported here are waterproof and wrinkled, thus, they could provide energy to wearable devices. [ABSTRACT FROM AUTHOR]

Novel materials with highly synchronized electrochromic (EC) and energy storage properties are needed to simultaneously visualize and quantify the real-time charge state of energy storage devices. Herein, a film was prepared by the Layer-by-Layer assembly of W 18 O 49 nanowires and a Preyssler-type polyoxometalate (POM) [P 5 W 30 O 110 ]15− (P 5 W 30). The introduction of amorphous POM decreased the band gap to 2.54 eV, which greatly facilitated the synergy between the EC and charge storage properties. Driven under a low voltage of −0.6 V, this W 18 O 49 /P 5 W 30 composite film displayed strong and reversible changes in its optical absorbance in both the visible and near-infrared regions, and it also showed the typical pseudocapacitance behavior with an area capacitance of 34.71 mF cm−2. Moreover, this film was able to simultaneously quantify and visualize its own energy storage state and photothermal conversion in real time by significant color changes (maximum chromaticity difference: 72.44) and high absorbance changes (1.11 at 650 nm and 1.11 at 1200 nm). In addition, a gel EC supercapacitor based on the W 18 O 49 /P 5 W 30 film as cathode and NiO film as anode exhibited an absorbance variation up to 0.75 and an area capacitance as high as 4.42 mF cm−2, and it successfully powered a light emitting diode using the stored electrical energy. This work not only broadens the application scope of POM-based EC materials but also provides a feasible design strategy for next-generation smart energy storage devices. [Display omitted] [ABSTRACT FROM AUTHOR]

Zinc hybrid supercapacitors (Zn‐HSCs) hold immense potential toward the next‐generation energy storage systems, effectively spanning the divide between conventional lithium‐ion batteries (LIBs) and supercapacitors. Unfortunately, the energy density of most of Zn‐HSCs has not yet rivalled the levels observed in LIBs. The electrochemical performance of aqueous Zn‐HSCs can be enhanced through the chemical functionalization of graphene‐based cathode materials with thiol moieties as they will be highly suitable for favoring Zn2+ adsorption/desorption. Here, a single‐step reaction is employed to synthesize thiol‐functionalized reduced graphene oxide (rGOSH), incorporating both oxygen functional groups (OFGs) and thiol functionalities, as demonstrated by X‐ray photoelectron spectroscopy (XPS) studies. Electrochemical analysis reveals that rGOSH cathodes exhibit a specific capacitance (540 F g−1) and specific capacity (139 mAh g−1) at 0.1 A g−1 as well as long‐term stability, with over 92% capacitance retention after 10 000 cycles, outperforming chemically reduced graphene oxide (CrGO). Notably, rGOSH electrodes displayed an exceptional maximum energy density of 187.6 Wh kg−1 and power density of 48.6 kW kg−1. Overall, this study offers an unprecedented powerful strategy for the design and optimization of cathode materials, paving the way for efficient and sustainable energy storage solutions to meet the increasing demands of modern energy applications. [ABSTRACT FROM AUTHOR]

We develop a new type of heterostructure nanocomposite made of reduced graphene oxide-boron carbon nitride nanosheets (rGOBCN) by B–C covalent bonds. The rGO-BCN nanocomposite delivers a large specific surface and excellent electrochemical properties, and is then constructed into flexible fabric-based high-performance supercapacitor electrodes based on the microfluidic electrospinning technology. [ABSTRACT FROM AUTHOR]

Supercapacitors are promising energy storage devices for the future-generation world. They store energy through a charge separation mechanism and have high charge-discharge rates, specific energy and specific power. It compares supercapacitors with batteries regarding cycle life, efficiency, self-discharge, temperature sensitivity, maintenance, cost, and other applications. The previous review work primarily focused on advancements in electrode materials. The review highlights recent advancements in electrode nanotechnology, focusing on tailored nanostructures, advanced carbon nanomaterials, 2D nanomaterials, binder-free electrodes, nanocomposites and advanced characterization techniques. The challenges and limitations associated with supercapacitor electrodes and potential devices for improved performance are also discussed. Furthermore, the review explores the application of supercapacitors in electric vehicles, renewable energy integration, grid stabilization, and uninterruptible power supply systems. It also presents future perspectives on enhancing supercapacitor electrodes for sustainable and efficient energy storage. • Advancements in supercapacitor electrode technology are reviewed. • State-of-the-art design and electrode characterization techniques are examined. • Application of the supercapacitor electrode technology is presented. • Issues and limitations with supercapacitor electrodes are discussed. • Future suggestions and prospects with supercapacitor electrodes are presented. [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]

Energy storage technology plays a critical role in integrating variable energy sources into the grid and ensuring energy consistency. Electrochemical supercapacitors are one of the most promising energy storage devices, as they present multiple advantages of high power density, rapid charge/discharge characteristics, and long‐term cycle stability. Herein, the NiCo2O4/molybdate nanocomposites are developed as electrode materials for supercapacitor applications. The NiCo2O4/molybdate nanocomposites are synthesized by a facile single‐pot hydrothermal method and are coated on a carbon cloth substrate to form flexible supercapacitor electrodes. The structures, chemical compositions, morphologies, and textural properties of these materials are carefully studied by X‐Ray diffraction, X‐Ray absorption spectroscopy, scanning electron microscopy/energy‐dispersive X‐Ray spectroscopy mapping, and N2 adsorption–desorption isotherms. The formation of spinel NiCo2O4 nanorods decorated with molybdate (AMoO4, A = Co, Ni) particles is confirmed for all samples. The NiCo2O4/CoMoO4 electrode exhibits pseudocapacitive behavior and provides the highest specific capacitance (287.28 F g−1 at current density 6 A g−1), about 5.5 times as high as that of NiCo2O4, with excellent cycle stability (107% specific capacitance retention after 1000 charge/discharge cycles at 1 A g−1). Therefore, the NiCo2O4/CoMoO4 composites can be considered as a promising pseudocapacitor electrode material. [ABSTRACT FROM AUTHOR]

Rare earth element doped bimetallic oxides are a new technology for improving the electrochemical performance of electrode materials. In this study, 0.5% La-NiMoO4 flower-like structured nanomaterials were directly grown on nickel-based surfaces through a fast and simple room temperature stirring method. The characterization methods such as SEM and TEM confirmed that the prepared product has a three-dimensional nanoflower-like structure, and also demonstrated that the prepared 0.5% La-NiMoO4 nanoflower material was successfully doped with rare earth elements. We also conducted electrochemical tests on the material, and the results showed that at a reaction time of 16 h, the 0.5% La-NiMoO4 flower-like structure exhibited excellent electrochemical performance. At a current density of 2 A g-1, the specific capacitance was 2100 F g-1. After 5500 cycles of charging and discharging at a current density of 1 A g-1, the capacitance retention rate was 99.8%. A 0.5% La-NiMoO4/Ni//Fe2O3/Ni asymmetric supercapacitor device was assembled using 0.5% La-NiMoO4 as the positive electrode and Fe2O3 as the negative electrode. At a current density of 15 A g-1 and a working window voltage of 1.8 V, the power density of the asymmetric device was 8000 W kg-1 (energy density 56.5 W h kg-1). At a current density of 5 A g-1, the device underwent 5000 cycles of charge and discharge, and the capacitance retention rate was 89.5%. The 0.5% La-NiMoO4 electrode material prepared in this study through a simple, fast, environmentally friendly method exhibits good electrochemical performance, making it a potential electrode material for development. [ABSTRACT FROM AUTHOR]

Here, poly(N‐acryloylglycinamide‐co‐vinyltriazole) p(NAGA‐co‐VTZ) supramolecular polymer hydrogel doped with carbonized and activated polypyrrole nanotubes as a high‐strength self‐healable material is presented for supercapacitors. Initially, the p(NAGA‐co‐VTZ) hydrogel films are synthesized by photopolymerization of N‐acryloylglycinamide and 1‐vinyl‐1,2,4‐triazole without the use of any cross‐linkers. The hydrogels demonstrated remarkable self‐healing ability via hydrogen bonding at temperatures above upper critical solubility temperature, excellent mechanical properties (0.86 MPa), large stretchability (1300%) and cut resistance. Subsequently, carbonized and ethanol/KOH‐activated polypyrrole nanotubes (acNTs) are prepared as the active material for electrochemical double‐layer capacitors (EDLC). Then, a symmetric self‐healable supercapacitor employing p(NAGA‐co‐VTZ) hydrogel, acNTs and aqueous 3 m KCl solution is assembled. Cyclic voltammetry and galvanostatic charge–discharge measurements show that the prepared device gives a specific capacitance of 282.62 F g−1 at 0.2 A g−1 and a high areal capacitance of 316.86 mF cm−2 at a scan rate of 10 mV s−1. Importantly, the supercapacitor operates over a wide voltage window (0–1.2 V) and provides excellent cyclic performance with capacitance retention of 97% after 10 000 cycles and 94% after self‐healing. In summary, the developed self‐healable supercapacitor exhibits considerable potential as a high‐performance energy storage device. [ABSTRACT FROM AUTHOR]

For the advancement of high‐energy asymmetric supercapacitors, the breakthrough point is matching charge storage capacity and balanced electrode kinetics between the positive and negative electrodes. Herein, Mn3O4 nanosheets composed of nanoparticles are anchored on activated carbon cloth (ACC) as the positive electrode by electrodeposition. FeOOH nanoparticles derived from NaFe3(SO4)2(OH)6 truncated cubes serve as the negative electrode. Due to the unique sheet‐like network structure, ultrahigh mass‐loading (73.3 mg cm−2), and enhanced kinetics, the Mn3O4@ACC electrode exhibits an ultrahigh specific capacitance of 12.77 F cm−2. Besides, the FeOOH@ACC electrode with a low‐crystalline structure also exhibits a maximum specific capacitance of 17.84 F cm−2. The Na+ diffusion process, the charge storage mechanism, and the electrochemical reaction kinetics of the Mn3O4@ACC are investigated by ex situ characterization. Theoretical calculations show that Mn3O4 has metallic electronic conductivity and reveal the adsorption and diffusion mechanism of Na ions during the electrode process. The assembled aqueous Mn3O4//FeOOH asymmetric supercapacitor device successfully extends the operating voltage to 2.2 V and exhibits a high energy density of 3.75 mWh cm−2 and ultra‐long cycle life (81.6% capacity retention after 26,000 cycles). Therefore, this study provides a feasible pathway for the further development of asymmetric supercapacitors with high energy density. [ABSTRACT FROM AUTHOR]

2D materials have garnered considerable interest in various applications from catalysis to energy storage. However, the self‐stacking and poor air stability of 2D materials (e.g., MXene) leads to serious performance degradation, in particular, of micro‐supercapacitors (MSCs) with narrow working voltage and low energy density. Here, a universal confined interfacial assembly strategy is demonstrated for controllably synthesizing a series of 2D mesoporous heterostructures for high‐voltage and high‐energy ionogel‐based MSCs. This assembly process reveals accurate controllability and extraordinary versatility, endowing the 2D mesoporous heterostructures with highly adjustable mesopore size (7–22 nm), tunable thickness (15–29 nm), variable carbon precursors (including oligochitosan, glucose, and sucrose), and replaceable 2D substrates (e.g., MXene, graphene, BN, and MoS2). As a proof of concept, the 2D mesoporous carbon@MXene based MSCs with ionic liquid ionogel electrolyte deliver ultrahigh voltage of 3.7 V, superior areal energy density of 181.3 µWh cm−2, excellent flexibility with 99% of capacitance retention at 180°, and excellent modular self‐integration for variable voltage/capacitance output, surpassing most reported MXene based MSCs. Therefore, this work will open a novel available paradigm for scalable fabrication of 2D mesoporous materials to target high‐performance and functional microscale power source. [ABSTRACT FROM AUTHOR]

Nanocomposites containing mixed transition metal oxides demonstrate significant promise as materials for supercapacitors, specifically due to their enhanced surface area, synergistic effect of multiple metal cations, excellent electrical conductivity, and improved electrochemical properties. In this study, we synthesized a nanocomposite with a nanograss array morphology consisting of SnO 2 /CoFe 2 O 4 /Fe 3 O 4 using an in-situ sol-gel method. For comparison, we synthesized a composite (CoFe 2 O 4 /Fe 3 O 4) without SnO 2. Through a systematic characterization employing various analytical techniques, we examined the structural, morphological, and textural attributes of the resulting composites. The results reveal that the phase percentages of CoFe 2 O 4 , SnO 2 , and Fe 3 O 4 were 38%, 33%, and 29% in the SnO 2 /CoFe 2 O 4 /Fe 3 O 4 composite. Also, the nanograss array of SnO 2 /CoFe 2 O 4 /Fe 3 O 4 is composed of nano-sized primary particles, while CoFe 2 O 4 /Fe 3 O 4 showed spherical-like nanoparticle morphology. The BET surface area of the SnO 2 /CoFe 2 O 4 /Fe 3 O 4 composite was found to be seven times higher than that of CoFe 2 O 4 /Fe 3 O 4. We also evaluated the electrochemical performance of the SnO 2 /CoFe 2 O 4 /Fe 3 O 4 composite as a cathode material for battery-type supercapacitors. The synergistic combination of SnO 2 and CoFe 2 O 4 /Fe 3 O 4 in the SnO 2 /CoFe 2 O 4 /Fe 3 O 4 electrode resulted in a high specific capacity of 465C g−1 at 1 A g−1, which is 2.5 times higher than the CoFe 2 O 4 /Fe 3 O 4 electrode. Additionally, the SnO 2 /CoFe 2 O 4 /Fe 3 O 4 electrode exhibited a remarkable rate capability of 87% at 10 A g−1 and excellent cyclic performance with 96% capacity retention after 5000 cycles. A hybrid supercapacitor was fabricated, featuring a cathode composed of a composite electrode consisting of SnO 2 /CoFe 2 O 4 /Fe 3 O 4 and an anode comprising activated carbon (AC). This fabricated SnO 2 /CoFe 2 O 4 /Fe 3 O 4 //AC HSC device configuration exhibited impressive performance characteristics, boasting a notable energy density of 38.4 Wh kg−1 at 1468.2 W kg−1. These findings underscore the significant impact of SnO 2 on the physio/electrochemical properties of the CoFe 2 O 4 /Fe 3 O 4 composite. The outstanding electrochemical performance of this electrode underscores its potential for application in next-generation hybrid supercapacitors. [ABSTRACT FROM AUTHOR]

Carbon-based materials have a broad range of applications. Among various carbon-based materials, reduced graphene oxide (rGO) is one of the facile options for supercapacitor (SCs) fabrication. The main reason is that it offers excellent conductance and enhanced surface redox reactivity. Therefore, there is a significant possibility that this material will boost the electrochemical efficiency of pseudocapacitive materials based on transition metals. Using the sonication route, we have synthesized NiO/CoFe 2 O 4 composite and decorated it with rGO. After structural and morphological analysis, the prepared electrode materials were subjected to electrochemical energy storage efficiency studies. The obtained data showed that the NiO/CoFe 2 O 4 @rGO exhibited a higher specific capacitance of 911.25 Fg-1 as compared to other electrode materials (such as NiO/CoFe 2 O 4 , NiO, and CoFe 2 O 4). Moreover, it was observed that NiO/CoFe 2 O 4 @rGO has low equivalence series resistance (ESR) as 0.29 Ω, in comparison to NiO/CoFe 2 O 4 , NiO, and CoFe 2 O 4. The enhanced conductivity of rGO and the good crystallinity of NiO and CoFe 2 O 4 are responsible for the excellent efficiency of the NiO/CoFe 2 O 4 @rGO electrode material. According to the obtained results, the NiO/CoFe 2 O 4 @rGO nanocomposite is an effective capacitive material for supercapacitors fabrication. [Display omitted] [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]

The utilization of heterostructured electrodes offers an effective approach to boost the energy density of supercapacitors without sacrificing their power density. However, the adoption of such materials is frequently impeded by sluggish reaction kinetics. Herein, an island‐like CoNi2S4@NiCo‐layered double hydroxide/biomass carbon (CoNi2S4@NiCo‐LDH/BC) heterostructure is synthesized by embedding CoNi2S4 in the interlayer of NiCo‐LDH nanosheets on BC through a partial in situ sulfidation process. Theoretical and experimental analyses indicate that this unique structural configuration lowers transport barriers and enhances ion adsorption capacity, leading to a significant improvement in ion/electron reaction kinetics. In addition, the embedded structural design effectively alleviates the significant volume expansion during charge–discharge process, while the robust BC framework prevents electrode degradation, thereby enhancing stability. These advantages enable the developed electrode material to achieve a high specific capacity (1655.75 C g−1 at 1 A g−1) and an extended cycle life (86.82% capacity retention after 10 000 cycles). Significantly, the assembled hybrid supercapacitor CoNi2S4@NiCo‐LDH/BC// activated carbon demonstrates a remarkable energy density of 95.57 Wh kg−1 at 866.61 W kg−1 and exceptional cycling stability, maintaining 95.16% capacity after 10 000 cycles. This research offers an effective strategy to promote ion/charge transfer and adsorption capacity of heterostructure and provides a new approach to the development of advanced supercapacitor electrodes. [ABSTRACT FROM AUTHOR]

Due to their unique physical and chemical properties, complex nanostructures based on carbon nanotubes and transition metal oxides are considered promising electrode materials for the fabrication of high-performance supercapacitors with a fast charge rate, high power density, and long cycle life. The crucial role in determining their efficiency is played by the properties of the interface in such nanostructures, among them, the type of chemical bonds between their components. The complementary theoretical and experimental methods, including dispersion-corrected density functional theory (DFT-D3) within GGA-PBE approximation, scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman, X-ray photoelectron, and X-ray absorption spectroscopies, were applied in the present work for the comprehensive investigation of surface morphology, structure, and electronic properties in CuOx/MWCNTs and NiOx/MWCNTs. As a result, the type of interfacial interaction and its correlation with electrochemical characteristics were determined. It was found that the presence of both Ni–O–C and Ni–C bonds can increase the contact between NiO and MWCNTs, and, through this, promote electron transfer between NiO and MWCNTs. For NiOx/MWCNTs, better electrochemical characteristics were observed than for CuOx/MWCNTs, in which the interfacial interaction is determined only by bonding through Cu–O–C bonds. The electrochemical properties of CuOx/MWCNTs and NiOx/MWCNTs were studied to demonstrate the effect of interfacial interaction on their efficiency as electrode materials for supercapacitor applications. [ABSTRACT FROM AUTHOR]

With the rapid development of the new energy industry, supercapacitors have become key devices in the field of energy storage. To forecast the remaining useful life (RUL) of supercapacitors, we introduce a new technology that integrates variational mode decomposition (VMD) with a bidirectional long short-term memory (BiLSTM) neural network. Firstly, the aging experiments of supercapacitors under various temperatures and voltages were carried out to obtain aging data. Then, VMD was implemented to decompose the aging data, which helped to eliminate disturbances, including capacity recovery and test errors. Then, the hyperparameters of BiLSTM were adjusted, employing the sparrow search algorithm (SSA) to improve the consistency between the input data and the network structure. After obtaining the optimal hyperparameters of BiLSTM, the decomposed aging data were input into BiLSTM for prediction. The experimental results showed that the VMD-SSA-BiLSTM model proposed in this paper has high prediction accuracy and high robustness under different temperatures and voltages, with an average RMSE of 0.112519, a decrease of 44.3% compared to BiLSTM, and a minimum of 0.031426. [ABSTRACT FROM AUTHOR]

This study proposed the hybrid energy storage paradigm (HESP) equipped with front-wheel permanent magnet synchronous motors (PMSMs) for battery electric vehicles (BEVs). In this case, all four wheels are driven by a single motor using mechanical coupling to distribute the motor's power to each wheel evenly. The HESP is a combination of several supercapacitors (SCs) and an NMC-lithium battery equipped with an advanced artificial neural network (ANN) that will enhance the regenerative braking system (RBS) efficiency of energy storage during braking. The three-phase inverter switching algorithm ensures efficient regenerative braking and fine adjustment of the brake force distribution. Under the RBS, the HESP with the ANN first transfers braking energy to the SC and, when the safety standard is reached, the SC transfers it to the battery. The RBS control maintains an even distribution of braking force at all distances to ensure stability during braking. The results show that a traditional BEV can drive 245.46 km (35 cycles), while an EV with an RBS-only battery can drive 282.56 km (40 cycles). An EV with HESP-RBS can drive 338.78 km (48 cycles), which is an increase of 93.32 km (13 cycles). The HESP-RBS increased the regenerative efficiency by 38.01% when compared to a traditional BEV. [ABSTRACT FROM AUTHOR]

[Display omitted] Utilizing diverse material combinations in heterogeneous structures has become an effective approach for regulating interface characteristics and electronic structures. The g-C 3 N 4 /Co 3 O 4 heterostructures were fabricated by uniformly modifying Co 3 O 4 nanoparticles onto discrete clusters of g-C 3 N 4 nanosheets. Then, they were subsequently employed as positive electrode materials for assembling hybrid supercapacitors. According to the first-principles calculation, Co 3 O 4 and g-C 3 N 4 formed Co-N ionic bonds, establishing interfacial space symmetry-broken heterojunction and direct exchange and superexchange between ions at the interface and sub-interface. This resulted in a high-density spin–orbit hybrid heterogeneous polarization interface, significantly improving the quantum capacitance of heterojunction materials. Experimental results showed that the heterojunction had a specific capacitance of 2662 F g−1 at 1 A g−1. When the power density was 750 W kg−1, the energy density reached 128 Wh kg−1. Even when the power density was 16850 W kg−1, it could show an energy density of 62.5 Wh kg−1. The g-C 3 N 4 /Co 3 O 4 heterojunction could realize high energy density charge storage as the cathode material of supercapacitors. The construction of heterogeneous polarization interfaces for high-energy quantum capacitors provides a new and effective method for the energy storage field. [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]

Electrochemistry forms the base of large-scale production of various materials, encompassing numerous applications in metallurgical engineering, chemical engineering, electrical engineering, and material science. This field is important for energy harvesting applications, especially supercapacitors (SCs) and photovoltaic (PV) devices. This review examines various electrochemical techniques employed to fabricate and characterize PV devices and SCs. Fabricating these energy harvesting devices is carried out by electrochemical methods, including electroreduction, electrocoagulation, sol-gel process, hydrothermal growth, spray pyrolysis, template-assisted growth, and electrodeposition. The characterization techniques used are cyclic voltammetry, electrochemical impedance spectroscopy, photoelectrochemical characterization, galvanostatic charge-discharge, and I–V curve. A study on different recently reported materials is also presented to analyze their performance in various energy harvesting applications regarding their efficiency, fill factor, power density, and energy density. In addition, a comparative study of electrochemical fabrication techniques with others (including physical vapor deposition, mechanical milling, laser ablation, and centrifugal spinning) has been conducted. The various challenges of electrochemistry in PVs and SCs are also highlighted. This review also emphasizes the future perspectives of electrochemistry in energy harvesting applications. [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]

The CeO 2 @γ-Fe 2 O 3 nanocomposites with varying CeO 2 content (0–50 mol%) were prepared by the sol-gel electrospinning. XRD analysis confirmed the phase transition from α-Fe 2 O 3 to cubic γ-Fe 2 O 3 with addition of Ce ions and dominant phase for 30, and 50% CeO 2 @γ-Fe 2 O 3 nanocomposites was cubic CeO 2. FESEM images revealed that the ribbon-like α-Fe 2 O 3 convert to the CeO 2 @γ-Fe 2 O 3 nanofibers. The EDS map images and FTIR confirmed the homogenous distribution of elements and chemical bonds, respectively. Interestingly, the induced phase transition resulted in superparamagnetic behavior of 10% CeO 2 @γ-Fe 2 O 3. The supercapacitive performance of the CeO 2 @γ-Fe 2 O 3 nanofibers grown on the nickel foam were examined by electrochemical analyzes. The 50% CeO 2 @γ-Fe 2 O 3 electrode demonstrated the highest specific capacitance of 1169.3 F g−1 at a current density of 1 A g−1 and the capacitance retention of 89.7% after 1000 cycles at 7 A g−1. Additionally, asymmetric supercapacitor (ASC) was assembled using CeO 2 @γ-Fe 2 O 3 and rGO as cathode and anode electrodes, respectively. The CeO 2 @γ-Fe 2 O 3 //rGO ASC displayed an energy density of 36.8 Wh kg−1 at a power density of 700 W kg−1, demonstrating its potential for use in energy storage systems. [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]

2D metal phosphorous trichalcogenides (MPCh3) have attracted considerable attention in sustainable energy storage and conversion due to their distinct physical and chemical characteristics, such as adjustable energy bandgap, significant specific surface area, and abundant active sites. However, research on 2D MPCh3 primarily focuses on electrocatalysis, and understanding its energy conversion and storage mechanisms remains incomplete. This review comprehensively summarizes recent advancements in energy storage and conversion using 2D MPCh3‐based materials of various structures. It begins with a discussion of the distinctive properties and preparation techniques of 2D MPCh3, followed by a focus on the rational design and development of these materials for diverse energy‐related applications, including rechargeable batteries, supercapacitors, electrocatalysis, photocatalysis, and desalination. Finally, it outlines the key challenges and prospects for future research on 2D MPCh3 materials. [ABSTRACT FROM AUTHOR]

In this study, S-CCO@Co(OH)2 ('CCO' representing CuCo2O4/Cu2O; 'S-'representing sulfur doping) was synthesized by hydrothermal method followed by electrodeposition. The multiple effects of S doping were studied by S doping and constructing 3D core–shell structure. S doping induced the reduction of Cu2+ and Co3+ to Cu+ and Co2+, respectively. Also, S partially replaces O and creates oxygen vacancies, which increases a number of active sites for the redox reaction enhancing the redox reaction activity. After the electrodeposition, S–Co bond is formed between the Co(OH)2 shell and the S-CCO core, which suggests a synergistic effect between S doping and core–shell structure. The formation of S–Co bond is conducive to electron and ion transport, thus improving electrochemical performance. After modification, the specific capacitance of S-CCO@Co(OH)2 is 4.28 times higher than CCO, up to 1730 Fg−1. Furthermore, the assembled S-CCO@Co(OH)2//activated carbon supercapacitor exhibits an energy density of 83.89 Whkg−1 at 848.81 Wkg−1 and a retention rate of 98.48% after 5000 charge and discharge cycles. Therefore, S doping and its mutual effect with the utilization of the core–shell structure considerably enhanced the electrochemical performance of the CCO-based electrodes, endowing its potential in further application. [ABSTRACT FROM AUTHOR]

Up to now, the mainstream adoption of renewable energy has brought about substantial transformations in the electricity and energy sector. This shift has garnered considerable attention within the scientific community. Supercapacitors, known for their exceptional performance metrics like good charge/discharge capability, strong power density, as well as extended cycle longevity, have gained widespread traction across various sectors, including transportation and aviation. Metal‐organic frameworks (MOFs) with unique traits including adaptable structure, highly customizable synthetic methods, and high specific surface area, have emerged as strong candidates for electrode materials. For enhancing the performance, MOFs are commonly compounded with other conducting materials to increase capacitance. This paper provides a detailed analysis of various common preparation strategies and characteristics of MOFs. It summarizes the recent application of MOFs and their derivatives as supercapacitor electrodes alongside other carbon materials, metal compounds, and conductive polymers. Additionally, the challenges encountered by MOFs in the realm of supercapacitor applications are thoroughly discussed. Compared to previous reviews, the content of this paper is more comprehensive, offering readers a deeper understanding of the diverse applications of MOFs. Furthermore, it provides valuable suggestions and guidance for future progress and development in the field of MOFs. [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]

The persisting quest for improving charge density, electronic conductivity and cyclic stability of the electrode material in supercapacitor (SC) applications still demands intensive research and advancements. This study also aims the aforementioned pursuit with the construction of hybrid supercapacitor using mixed metal oxides with the incorporation of metal and supported with porous carbon to improve the charge density, electrical conductivity and cyclic stability, respectively. A covalent organic framework (COF) was synthesized and doped with nickel (Ni2+) and cobalt (Co2+) ions followed by carbonization at 1000 °C for 3 h to generate NiCo/NiO–CoO surrounded N-doped porous carbon (NPC) framework. The X-ray diffraction reveals that nickel considerably impacts the crystallinity of NiCo/NiO–CoO and the Raman spectroscopy revealed that the NiCo/NiO-CoO-NPC with an equal molar ratio of Ni2+ and Co2+ ions (NiCo/NiO-CoO-NPC-2) offered the highest degree of graphitization. The electron microscopic images showed the formation of flower-like morphology of NiCo/NiO-CoO-NPC-2 with a size of 250 nm and the greater number of flowers on NPC's surface could augment the electrochemical activity of the composite material. The NiCo/NiO–CoO-NPC-2 offered an attractive specific capacitance (Cs) of 845 F g−1 @ 1 A g−1 and preserves 93% capacity retention @ 10 A g−1 after 6000 charge-discharge cycles while exploited in SC application. The metal-free COF carbonized at 900 °C (CCOF-900) is utilized as the negative electrode with a Cs of 286 F g−1 @ 1 A g−1 for the construction of an asymmetric supercapacitor device and the NiCo/NiO-CoO-NPC-2//CCOF-900 device delivered efficient energy of 54 Wh kg−1 at a power density of 633 W kg−1. Covalent organic framework-derived flower-like composition dependent NiCo/NiO–CoO surrounded by N-doped porous carbon was constructed for aqueous asymmetric supercapacitor. [Display omitted] • COF-derived flower-like NiCo/NiO–CoO surrounded by N-doped porous carbon was prepared. • Equimolar Ni2+/Co2+-based composite exhibited excellent surface area and graphitization. • NiCo/NiO-CoO-NPC-2 offered attractive Cs of 845 F g−1 @ 1 A g−1 and 93% retention after 6000 cycles. • CCOF-900 as the negative electrode showed the Cs of 286 F g−1 @ 1 A g−1 • The NiCo/NiO-CoO-NPC-2//CCOF-900 ASC delivered energy of 54 Wh kg−1 at a power density 633 W kg−1 [ABSTRACT FROM AUTHOR]

As an emerging energy storage device, zinc ion hybrid supercapacitors (ZHSCs) have attracted wide interest because of their intrinsic safety, high energy/power densities, and long cycle life. However, problems of liquid leakage and zinc dendrite growth seriously hinder its widespread application. To solve the above problems, a gelatin/polyacrylamide/agarose/Zn(CF3SO3)2 hydrogel electrolyte (G/PAAm/AG/Zn(CF3SO3)2) was designed by constructing a multi-crosslinked network of physically crosslinked gelatin and agarose coupled with chemically crosslinked polyacrylamide. The tested results show that G/PAAm/AG/Zn(CF3SO3)2 can effectively prevent electrolyte leakage and inhibit zinc dendrite growth. Moreover, G/PAAm/AG/Zn(CF3SO3)2 possesses high ionic conductivity (2.64 S m−1), high tensile strength (72.4 kPa at 489.2%), and high compressive strength (164.5 kPa at 80%). Additionally, a highly connected porous carbon material (denoted as HSSPC) with high specific surface area (2930.9 m2 g−1) was synthesized, which exhibits a reversible capacity of 183.5 mA h g−1 and good cycling stability (the capacity remains at 96.6% after 10 000 cycles). More importantly, the quasi-solid-state ZHSC based on G/PAAm/AG/Zn(CF3SO3)2 and HSSPC delivers a high specific capacity (122.8 mA h g−1, 0.25 A g−1), high energy/power densities (96.1 Wh kg−1/14.4 kW kg−1), and good cycling stability (capacity retention can be maintained at 114.0% of the initial capacity after 14 000 cycles). [ABSTRACT FROM AUTHOR]

Electrochemical supercapacitors are effectively involved and have potential attention in recent years due to the greatest advancements in energy storage system. In that, the electrode materials play a crucial role in achieving better electrochemical concert. In this work, three-dimensional NiO nanostructures were proposed as the high-capacity positive electrode for hybrid supercapacitors. In addition, the 3D-NiO electrode achieved a capacitance of 1100 F g−1 (605 C g−1) alone with 95.5% super stability retention. Similarly, a carbon-doped g-C3N4 nanosheet electrode involved as a negative electrode, which delivers a stability retention of 89.9%. Further, a hybrid supercapacitor device was made up of NiO as a positive, carbon-doped g-C3N4 as a negative material in an aqueous system, which shows the remarkable energy and power densities of 31.7 Wh kg−1 and 3625 W kg−1. The device delivers an admirable electrochemical performance that provides a huge active surface during the ion transportation process. These tolerable electrochemical results of this gathered hybrid supercapacitor device will be promoted as a various electronic tool in future generation. [ABSTRACT FROM AUTHOR]