NiCo2S4 nanosheet grafted SiO2@C core-shelled spheres as a novel electrode for high performance supercapacitors

Fabrication and characterization of Sb2O3-MoS2nanocomposites for high performance supercapacitor applications

Binary nanocomposite-based electrodes have been studied extensively in recent times owing to their multiple oxidation states, excellent physico-chemical features, and combined morphology, which are suitable for increasing the electrochemical performance of supercapacitors. The present work deals with Sb2O3-MoS2nanocomposites electrode for supercapacitor applications. The x-ray diffraction (XRD), Raman, scanning electron microscope (SEM), energy dispersive x-ray (EDX), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED) and x-ray photoelectron spectroscopy (XPS) characterizations have been studied to analyze the phase formation, vibrational modes, morphology, elemental composition and binding energies of the prepared Sb2O3-MoS2nanocomposites electrode material, as well as their electrochemical measurements such as cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS) have been analyzed. The developed Sb2O3-MoS2nanocomposites electrode provides a high specific capacitance of 454.3 F g-1at the current density of 1 A g-1. Further, the hybrid supercapacitor device has been constructed which shows 104.04 F g-1of specific capacitance at 2 A g-1and manifests a good energy density of 24.42 Wh kg-1at a power density of 1299.89 W kg-1. Additionally, the hybrid device Sb2O3-MoS2//AC exhibits a good capacitive retention of 90.6% and a coulombic efficiency of 100.45% at 10 A g-1over 8000 cycles.

The Hydrothermal-Assisted Approach Improves the Photocatalytic and Energy Storage Performance of Novel CuSe-TiO2-GO Composite

This study reports a novel CuSe-TiO2-GO composite, synthesized by a facile hydrothermal method at a controlled temperature, and investigates its electrochemical performance for supercapacitors (SCs) and photocatalytic behavior for degrading methylene blue (MB) dye. The compositional phase structure and chemical bond interaction were thoroughly investigated. The as-fabricated pristine, binary, and ternary composites underwent comprehensive characterization employing spectroscopic techniques and electrochemical analysis. Compared with pure and binary compounds (CuSe, TiO2, and binary CuSe-TiO2 composites), the ternary CuSe-TiO2-GO composites demonstrated a high degradation efficiency while degrading MB in less than just 80 min (240 min, 100 min, and 140 min, respectively). The photocatalytic activity of the ternary CuSe-TiO2-GO composites is enhanced due to the highly positive conduction band of CuSe, leading to the quick excitation of electrons to the conduction band of CuSe. Subsequently, graphene oxide (GO) left holes on the photocatalyst surface for MB, as GO assisted the photoexcited electron-hole pairs, resulting in enhanced photocatalytic performance. The CuSe-TiO2-GO electrode for the supercapacitor indicates a 310.6 F/g and 135.2 F/g capacitance when the discharge current upsurges from 1 to 12 A/g. The good photocatalytic and energy storage performance is due to the smaller charge transfer resistance, which promotes efficient separation of electron-hole pairs.

Exploring the electrochemical properties of CuSe-decorated NiSe2 nanocubes for battery-supercapacitor hybrid devices

Chalcogenides, a promising class of electrode materials, attracted massive popularity owing to their exciting features of high conductive nature, high capacity, rich redox activities, and structural functionalities, making them the first choice for the electrochemical energy domain. This paper reported a new NiSe2-CuSe nanocomposite prepared via a wet-chemical synthesis followed by a low-cost and simple hydrothermal reaction. The physical characterization showed cubes and nanoparticles type morphological features of NiSe2 and CuSe products, while their composite reveals a combined morphological characteristic. The electrochemical properties were tested in an aqueous solution, demonstrating that the NiSe2-CuSe nanocomposite exhibits a high capacity of 376 C g-1, low resistance, good reversibility and rate capability in a three-electrode mode than bulk counterparts. For practical aspects, a battery-hybrid supercapacitor (BHSC) is developed with NiSe2-CuSe nanocomposite, and activated carbon (AC) serves as cathode and anode in two-cell mode operation. The built NiSe2-CuSe||AC/KOH BHSC expanded the voltage to 1.8 V and delivered the highest capacitance of 148 F g-1 and 55 F g-1 from 1 to 10 A g-1, suppressing most of the previously existing literature reports. Also, our built NiSe2-CuSe||AC/KOH BHSC displayed a high-power delivery of 8928 W kg-1 at a maximum energy density of 66.6 W h kg-1 and retained 91.7% capacitance after a long way of 10,000 cycles. These outstanding results demonstrate that metal selenides can be effectively utilized as alternative electrodes with high energy, rate performance, and long-term durability for advanced energy conversion and storage devices.

Hydrothermal assisted synthesis of hierarchical SnO2 micro flowers with CdO nanoparticles based membrane for energy storage applications

Hierarchical nanostructures with appropriate morphology and surface functionalities are highly desired to achieve an optimized electrochemical property for active electrode materials. This work renders the facile hydrothermal synthesis of CdO, SnO₂, and CdO-SnO₂ nanocomposite, and their capacitive performance was tested. The formation of the pure samples and their composite was committed by low-temperature Raman spectroscopy and x-ray diffraction studies which revealed the tetragonal and cubic structures of CdO and SnO₂ powder samples with good crystallinity and purity. The morphological postmortem reveals the formation of nanoparticles morphology of CdO with a highly smooth surface appearance. Besides, the SnO₂ illustrates the morphology of the micro flowers composed of ultrathin nanosheets. More specifically, the electrochemical properties indicate the pseudocapacitive charge storage mechanism based on cyclic voltammetry and chronopotentiometry analysis. The CdO-SnO₂ composite electrode displayed a higher capacitance due to additional pores/space offered for active sites and continuously allowed electrolyte ions to interact with the inner/outer surface of the electrode. These exciting findings led us to design and fabricate battery hybrid supercapacitors (BHSC) from CdO-SnO_2, and activated carbon (AC), referred to as CdO-SnO₂//AC BHSC, attains a high power delivery (5717 W/kg), and a maximum energy density of 42 Wh/kg at low discharge rate. Noteworthy, a stable cycling performance was obtained with only 91.3% retention after 8000 cycling at a large discharge current of 10 A/g, denoting the magnificent durability of the active electrode material.

Iron-selenide-based titanium dioxide nanocomposites as a novel electrode material for asymmetric supercapacitors operating at 2.3 V

This study portrays a facile wet-chemical synthesis of FeSe2/TiO2 nanocomposites for the first time for advanced asymmetric supercapacitor (SC) energy storage applications. Two different composites were prepared with varying ratios of TiO2 (90 and 60%, symbolized as KT-1 and KT-2) and their electrochemical properties were investigated to obtain an optimized performance. The electrochemical properties showed excellent energy storage performance owing to faradaic redox reactions from Fe2+/Fe3+ while TiO2 due to Ti3+/Ti4+ with high reversibility. Three-electrode designs in aqueous solutions showed a superlative capacitive performance, with KT-2 performing better (high capacitance and fastest charge kinetics). The superior capacitive performance drew our attention to further employing the KT-2 as a positive electrode to fabricate an asymmetric faradaic SC (KT-2//AC), exceeding exceptional energy storage performance after applying a wider voltage of 2.3 V in an aqueous solution. The constructed KT-2/AC faradaic SCs significantly improved electrochemical parameters such as capacitance of 95 F g-1, specific energy (69.79 Wh kg-1), and specific power delivery of 11529 W kg-1. Additionally, extremely outstanding durability was maintained after long-term cycling and rate performance. These fascinating findings manifest the promising feature of iron-based selenide nanocomposites, which can be effective electrode materials for next-generation high-performance SCs.

Boosting the electrochemical performance of ZnO nanomaterials through a conductive CuS matrix for aqueous supercapacitors

The impressive electrochemical performance of metal oxides/metal sulfides and their derivatives are proven to be innovative electrodes for achieving a remarkable performance for supercapacitors.

A New CuSe-TiO2-GO Ternary Nanocomposite: Realizing a High Capacitance and Voltage for an Advanced Hybrid Supercapacitor

A high capacitance and widened voltage frames for an aqueous supercapacitor system are challenging to realize simultaneously in an aqueous medium. The severe water splitting seriously restricts the narrow voltage of the aqueous electrolyte beyond 2 V. To overcome this limitation, herein, we proposed the facile wet-chemical synthesis of a new CuSe-TiO₂-GO ternary nanocomposite for hybrid supercapacitors, thus boosting the specific energy up to some maximum extent. The capacitive charge storage mechanism of the CuSe-TiO₂-GO ternary nanocomposite electrode was tested in an aqueous solution with 3 M KOH as the electrolyte in a three-cell mode assembly. The voltammogram analysis manifests good reversibility and a remarkable capacitive response at various currents and sweep rates, with a durable rate capability. At the same time, the discharge/charge platforms realize the most significant capacitance and a capacity of 920 F/g (153 mAh/g), supported by the impedance analysis with minimal resistances, ensuring the supply of electrolyte ion diffusion to the active host electrode interface. The built 2 V CuSe-TiO₂-GO||AC-GO||KOH hybrid supercapacitor accomplished a significant capacitance of 175 F/g, high specific energy of 36 Wh/kg, superior specific power of 4781 W/kg, and extraordinary stability of 91.3% retention relative to the stable cycling performance. These merits pave a new way to build other ternary nanocomposites to achieve superior performance for energy storage devices.

Rational design of self-supported Ni3S2 nanoparticles as a battery type electrode material for high-voltage (1.8 V) symmetric supercapacitor applications

We developed a high performance SSC device with excellent electrochemical performance in terms of specific capacitance, rate capability, energy density and power density which surpasses most of the reports.

CuCo2O4 nanoparticles wrapped in a rGO aerogel composite as an anode for a fast and stable Li-ion capacitor with ultra-high specific energy

To meet practical application requirements, high specific energy and specific power and excellent cyclability are highly desired.

Fabrication of a High-Energy Flexible All-Solid-State Supercapacitor Using Pseudocapacitive 2D-Ti3C2Tx-MXene and Battery-Type Reduced Graphene Oxide/Nickel-Cobalt Bimetal Oxide Electrode Materials

Owing to excellent metallic conductivity, hydrophilic surfaces, and surface redox properties, a two-dimensional (2D) metal carbide of Ti₃C₂T_x-MXene could serve as a promising pseudocapacitive electrode material for energy storage devices. Meanwhile, the 2D reduced graphene oxide (rGO) combining with the hierarchical cubic spinel nickel-cobalt bimetal oxide (NiCo₂O₄) nanospikes could control ion diffusion for charge storage, thereby facilitating the improvement of the energy density of a supercapacitor. As per the strategy, the pseudocapacitive 2D Ti₃C₂T_x was loaded on a flexible acid-treated carbon fiber (ACF) backbone to prepare a Ti₃C₂T_x/ACF negative electrode by a convenient drop-casting method. Meanwhile, 2D rGO was deposited on ACF by a simple dip-dry process, which was further decorated by the spinel NiCo₂O₄ nanospikes using a hydrothermal method to obtain a NiCo₂O₄@rGO/ACF positive electrode. The fabricated Ti₃C₂T_x/ACF electrode exhibited an excellent specific capacitance of 246.9 F/g (197.5 mF/cm²) at 4 mA/cm² along with 96.7% capacity retention over 5000 charge/discharge cycles, whereas the NiCo₂O₄@rGO/ACF electrode showed a specific capacitance of 1487 F/g (458.3 mA h/g) at 3 mA/cm² with a cycling stability of 88.2% over 10 000 charge/discharge cycles. As a result, a flexible all-solid-state hybrid supercapacitor (FHSC) device using the pseudocapacitive Ti₃C₂T_x/ACF on the negative side with a widespread voltage window and the battery-type NiCo₂O₄@rGO/ACF on the positive side with high electrochemical activity delivered an excellent volumetric capacitance of 2.32 F/cm³ (141.9 F/g) at a current density of 5 mA/cm² with a high-energy density of 44.36 Wh/kg (0.72 mWh/cm³) at a power density of 985 W/kg (16.13 mW/cm³) along with a cycling stability of 90.48% over 4500 charge/discharge cycles. Therefore, the pseudocapacitive 2D Ti₃C₂T_x/ACF negative electrode could replace carbon-based electrodes and a combination of it with the battery-type NiCo₂O₄@rGO/ACF positive electrode should be a promising way to step up the energy density of a supercapacitor.

Ingenious preparation of N/NiOx co-doped hierarchical porous carbon nanosheets derived from chitosan nanofibers for high-performance supercapacitors

It is still a key challenge to find suitable materials and methods to obtain super capacitors (SCs) with high specific capacitance due to the difficulty of balancing low theoretical capacity of conventional carbon materials and the poor ion transportability of transition metal oxide. In this work, N Ni dual-doped porous carbon nanosheets (NiO_x-NCNSs) are prepared through a novel way using original N-doped chitosan nanofibers and nickel nitrate to form honeycomb layered structure constructed by 2D fiber network as precursors. NiO_x-NCNS exhibits a high specific surface area of 1847.4 m² g^-1 with a rich N content of up to 5.16 wt% and shows a higher specific capacitance of 614.6 F g^-1 at a current density of 1 A g^-1 than that of carbon nanosheets of undoped Ni (NCNS) (427.5 F g^-1). More specifically, the SC assembled using NiO_x-NCNS electrodes achieves a high energy density of 20.3 W h kg^-1 at a power density of 240.9 W kg^-1, which is superior to most of the CNS-based SCs that have been reported. After 10 000 cycles, the symmetric SC retains approximately 85.61% of the initial capacitance. The strategy provided in this work probes the feasibility of high-performance SCs.

Nanoporous Carbon Derived from Green Material by an Ordered Activation Method and Its High Capacitance for Energy Storage

Carbon materials have been widely used as electrode materials for supercapacitors, while the current carbon precursors are mainly derived from fossil fuels. Biomass-derived carbon materials have become new and effective materials for electrodes of supercapacitors due to their sustainability, low pollution potential, and abundant reserves. Herein, we present a new biomass carbon material derived from water hyacinth by a novel activation method (combination of KOH and HNO₃ activation). According to the electrochemical measurements, the material presents an ultrahigh capacitance of 374 F g^-1 (the current density is 1 A g^-1). Furthermore, the material demonstrates excellent rate performance (105 F g^-1 at a higher density of 20 A g^-1) and ideal cycling stability (87.3% capacity retention after 5000 times charge-discharge at 2 A g^-1). When used for a symmetrical supercapacitor device, the material also shows a relatively high capacity of 330 F g^-1 at 1 A g^-1 (a two-electrode system). All measurements suggest the material is an effective and noteworthy material for the electrodes of supercapacitors.