Microwave assisted reflux synthesis of NiCo 2 O 4 /NiO composite: Fabrication of high performance asymmetric supercapacitor with Fe 2 O 3

Highly Stable S2--Doped-rGO@Fe2.57Mn0.43O4@C Hybrid Heterostructures by Sulfur- Doping of Graphene-Coated 3D Fe2.57Mn0.43O4 Nanorods on rGO Nanosheets for High-Performance Fast Charge/Discharge Ni/Fe Batteries

Multicomponent transition metal heterostructures is constructed through a heteroatomic doping method sandwiched by the dual carbon layers. The promising strategy combines iron and manganese ions into a novel Fe2.57Mn0.43O4 heterostructure on the surface of the rGO nanosheets, followed by sulfur-doping and calcination processes to achieve S2--doped-rGO@Fe2.57Mn0.43O4@C heterostructure. Note that S2--doped Fe2.57Mn0.43O4 nanorods encapsulated by the carbon coating layers on the rGO nanosheets as the backbone are expected to restrict nanorods from collapsing during the charge-discharge processes. The S2--doping in heterostructures can build stabilized solid electrolyte interphase on or near the surface of the Fe2.57Mn0.43O4 nanorods. Moreover, Mn heteroatomic doping can optimize the crystalline structure of the Fe2.57Mn0.43O4. The exposed active sites and kinetics of S2--doped-rGO@Fe2.57Mn0.43O4@C heterostructure are significantly improved. As a result, the as-assembled batteries can achieve a high capacitance of 1410 F g-1 at 1 A g-1 with a high capacitance retention of 75% at 16 A g-1. Furthermore, the batteries are guaranteed a prolonged cycle life of 1000 cycles with 92.3% capacitance retention. The as-assembled NiAl-LDH (Ni-Al layered double hydroxide)//S2--doped-rGO@Fe2.57Mn0.43O4@C battery leads to excellent electrochemical properties (65.4 Wh kg-1 at 763.2 W kg-1, 9925.8 W kg-1 at a 43.9 Wh kg-1).

Carbon Nanofibers as Supporting Substrate for Growth of Polyaniline Nanorods on Fe2O3 Nanoneedles toward Electrochemical Energy Storage

Iron-oxide (Fe2O3) nanoneedles were first in situ grown on the surface of carbon nanofibers (CNFs) using hydrothermal and N2 annealing process, and then polyaniline (PANI) was coated on the Fe2O3 nanoneedles to form network-like nanorods through dilute solution polymerization. The PANI/Fe2O3/CNFs binder-free electrode exhibited a high specific capacitance of 603 F/g at 1 A/g with good rate capability. (The capacitance loss was about 48.3% when the current density increased from 1.0 to 5.0 A/g.) It was caused by the fact that the PANI/Fe2O3/CNFs with a well-connected structure could provide a continuous electron transport path and improve the conductivity of the entire electrode. The solid-state hybrid PANI/Fe2O3/CNFs∥PANI/Fe2O3/CNFs symmetric device also achieved a high energy density of 29.85 Wh/kg at a power density of 500 W/kg. This universal compatible synthetic method for the PANI/Fe2O3/CNFs electrode could extend to other supercapacitor electrode systems, making it easy to fabricate various ternary electrodes for supercapacitors.

Bendable quasi-solid-state aqueous sodium-ion batteries operated at -30 °C

Aqueous sodium-ion batteries (ASIBs) have garnered considerable attention for large-scale energy storage because of inherent safety and the Na abundance. Nonetheless, the solidification of aqueous electrolytes under sub-zero conditions results in diminished ionic conductivity and increased viscosity, hindering the electrochemical performance and versatility of ASIBs. Herein, we introduce a novel freeze-tolerant ASIB using antifreezing ethylene glycol-polyacrylamide-sodium perchlorate hydrogel electrolyte, paired with new couple of Na3MnTi(PO4)3 cathode and Fe-based anode. The addition of ethylene glycol in the electrolyte enhances ionic conductivity at cold temperatures and optimizes electrode capacity by reduced hydrogen bonding within the water molecules and a decline in free water activity. The pronounced interaction between ethylene glycol and water, combined with the cooperative effect of the crosslinked polyacrylamide network, enables the hydrogel electrolyte to effectively suppress water solidification and maintain better water-retaining capability, achieving remarkable mechanical extensibility and good ionic conductivity (2.5 mS cm-1) at - 40 °C. Consequently, the ASIB equipped with hydrogel electrolyte delivers high energy density of 43.6 Wh kg-1 and retains 64 % at - 30 °C. Furthermore, the flexible ASIB demonstrates robust mechanical durability when bent or compressed, efficiently powering electronic devices even at - 30 °C. Our findings will pave the way for advancing low-temperature ASIBs with hydrogel-based electrolytes.

P-N heterojunction NiO/ZnO nanowire based electrode for asymmetric supercapacitor applications

Nickel-based oxides are selected for their inexpensive cost, well-defined redox activity, and flexibility in adjusting nanostructures via optimization of the synthesis process. This communique explores the field of energy storage for hydrothermally synthesized NiO/ZnO nanowires by analysing their capacitive behaviour. The p-type NiO was successfully built onto the well-ordered mesoporous n-type ZnO matrix, resulting in the formation of p-n heterojunction artefacts with porous nanowire architectures. NiO/ZnO nanowire-based electrodes exhibited much higher electrochemical characteristics than bare NiO nanowires. The heterojunction at the interface between the NiO and ZnO nanoparticles, their specific surface area, as well as their combined synergetic influence, are accountable for the high specific capacitance (Cs) of 1135 Fg-1at a scan rate of 5 mV s-1. NiO/ZnO nanowires show an 18% dip in initial capacitance even after 6000 cycles, indicating excellent capacitance retention and low resistance validated by electrochemical impedance spectroscopy. In addition, the specific capacitance, energy and power density of the solid state asymmetric capacitor that was manufactured by employing NiO/ZnO as the positive electrode and activated carbon as the negative electrode were found to be 87 Fg-1, 23 Whkg-1and 614 Wkg-1, respectively. The novel electrode based on NiO/ZnO demonstrates excellent electrochemical characteristics all of which point to its promising application in supercapacitor devices.

Fe2O3/Porous Carbon Composite Derived from Oily Sludge Waste as an Advanced Anode Material for Supercapacitor Application

It is urgent to improve the electrochemical performance of anode for supercapacitors. Herein, we successfully prepare Fe₂O₃/porous carbon composite materials (FPC) through hydrothermal strategies by using oily sludge waste. The hierarchical porous carbon (HPC) substrate and fine loading of Fe₂O₃ nanorods are all important for the electrochemical performance. The HPC substrate could not only promote the surface capacitance effect but also improve the utilization efficiency of Fe₂O₃ to enhance the pseudo-capacitance. The smaller and uniform Fe₂O₃ loading is also beneficial to optimize the pore structure of the electrode and enlarge the interface for faradaic reactions. The as-prepared FPC shows a high specific capacitance of 465 F g^-1 at 0.5 A g^-1, good rate capability of 66.5% retention at 20 A g^-1, and long cycling stability of 88.4% retention at 5 A g^-1 after 4000 cycles. In addition, an asymmetric supercapacitor device (ASC) constructed with FPC as the anode and MnO₂/porous carbon composite (MPC) as the cathode shows an excellent power density of 72.3 W h kg^-1 at the corresponding power density of 500 W kg^-1 with long-term cycling stability. Owing to the outstanding electrochemical characteristics and cycling performance, the associated materials' design concept from oily sludge waste has large potential in energy storage applications and environmental protection.

Carbon-α-Fe2O3 Composite Active Material for High-Capacity Electrodes with High Mass Loading and Flat Current Collector for Quasi-Symmetric Supercapacitors

In this work, we report the synthesis of an active material for supercapacitors (SCs), namely α-Fe2O3/carbon composite (C-Fe2O3) made of elongated nanoparticles linearly connected into a worm-like morphology, by means of electrospinning followed by a calcination/carbonization process. The resulting active material powder can be directly processed in the form of slurry to produce SC electrodes with mass loadings higher than 1 mg cm−2 on practical flat current collectors, avoiding the need for bulky porous substrate, as often reported in the literature. In aqueous electrolyte (6 M KOH), the so-produced C-Fe2O3 electrodes display capacity as high as ~140 mAh g−1 at a scan rate of 2 mV s−1, while showing an optimal rate capability (capacity of 32.4 mAh g−1 at a scan rate of 400 mV s−1). Thanks to their poor catalytic activity towards water splitting reactions, the electrode can operate in a wide potential range (−1.6 V–0.3 V vs. Hg/HgO), enabling the realization of performant quasi-symmetric SCs based on electrodes with the same chemical composition (but different active material mass loadings), achieving energy density approaching 10 Wh kg−1 in aqueous electrolytes.

Ternary Nanohybrid of Ni3S2/CoMoS4/MnO2 on Nickel Foam for Aqueous and Solid-State High-Performance Supercapacitors

To overcome the issues related to supercapacitor (SC) electrodes, such as high cost, low specific capacitance (C_s), low energy density (ED), requirements for expensive binder, etc., binderless electrodes are highly desirable. Here, a new ternary nanohybrid is presented as a binder-free SC electrode based on Ni₃S₂, CoMoS₄, and MnO₂. A facile two-step hydrothermal route, followed by a short thermal annealing process, is developed to grow amorphous polyhedral structured CoMoS₄ and further wrap MnO₂ nanowires on Ni foam. This rationally designed binder-free electrode exhibited the highest C_s of 2021 F g⁻¹ (specific capacity of 883.8 C g⁻¹ or 245.5 mAh g⁻¹) at a current density of 1 A g⁻¹ in 1 M KOH electrolyte with a highly porous surface morphology. This electrode material exhibited excellent cycling stability (90% capacitance retention after 4000 cycles) due to the synergistic contribution of individual components and advanced surface properties. Furthermore, an aqueous binder-free asymmetric SC based on this ternary composite exhibited an ED of 20.7 Wh kg⁻¹, whereas a solid-state asymmetric SC achieved an ED of 13.8 Wh kg⁻¹. This nanohybrid can be considered a promising binder-free electrode for both aqueous and solid-state asymmetric SCs with these remarkable electrochemical properties.

In situ synthesis of Fe2O3 nanosphere/Co3O4 nanowire-connected reduced graphene oxide hybrid networks for high-performance supercapacitors

Three-dimensional (3D) hybrid networks consisting of reduced graphene oxide (rGO) sheets interconnected by Co₃O₄ nanowires (rGO/Co₃O₄), followed by the decoration of Fe₂O₃ nanospheres (NSs) (rGO/Co₃O₄@Fe₂O₃), were demonstrated by a facile hydrothermal method, with which the rGO/Co₃O₄ networks acted as nucleation sites for the in situ synthesis of Fe₂O₃ NSs. The intimate contacts between rGO, Co₃O₄ NWs and Fe₂O₃ NSs, which result in an excellent conductive behavior, provide a unique structure with huge potential for electrochemical property promoted electrochemical supercapacitors. The rGO/Co₃O₄@Fe₂O₃ hybrid networks as electrodes exhibit a high capacitance of 784 F g^-1 at 1 A g^-1 with 83% retention of the initial capacitance as the current density increases from 1 to 10 A g^-1, which is explained by the graphene-based interconnected structure owing to the advantages of accommodating the volume expansion between Co₃O₄ NWs and Fe₂O₃ NSs. The supercapacitor was assembled by applying a nickel aluminum layered double hydroxide (NiAl-LDH) structure and rGO/Co₃O₄@Fe₂O₃ as the electrode materials and yields an energy density of 70.78 W h kg^-1 at a power density of 0.29 kW kg^-1. The energy density can maintain 24.24 W h kg^-1 with 9.94 kW kg^-1.

NiCo2O4 Nano-/Microstructures as High-Performance Biosensors: A Review

Non-enzymatic biosensors based on mixed transition metal oxides are deemed as the most promising devices due to their high sensitivity, selectivity, wide concentration range, low detection limits, and excellent recyclability. Spinel NiCo2O4 mixed oxides have drawn considerable attention recently due to their outstanding advantages including large specific surface area, high permeability, short electron, and ion diffusion pathways. Because of the rapid development of non-enzyme biosensors, the current state of methods for synthesis of pure and composite/hybrid NiCo2O4 materials and their subsequent electrochemical biosensing applications are systematically and comprehensively reviewed herein. Comparative analysis reveals better electrochemical sensing of bioanalytes by one-dimensional and two-dimensional NiCo2O4 nano-/microstructures than other morphologies. Better biosensing efficiency of NiCo2O4 as compared to corresponding individual metal oxides, viz. NiO and Co3O4, is attributed to the close intrinsic-state redox couples of Ni3+/Ni2+ (0.58 V/0.49 V) and Co3+/Co2+ (0.53 V/0.51 V). Biosensing performance of NiCo2O4 is also significantly improved by making the composites of NiCo2O4 with conducting carbonaceous materials like graphene, reduced graphene oxide, carbon nanotubes (single and multi-walled), carbon nanofibers; conducting polymers like polypyrrole (PPy), polyaniline (PANI); metal oxides NiO, Co3O4, SnO2, MnO2; and metals like Au, Pd, etc. Various factors affecting the morphologies and biosensing parameters of the nano-/micro-structured NiCo2O4 are also highlighted. Finally, some drawbacks and future perspectives related to this promising field are outlined.

Hollow 3D Frame Structure Modified with NiCo2 S4 Nanosheets and Spinous Fe2 O3 Nanowires as Electrode Materials for High-Performance All-Solid-State Asymmetric Supercapacitors

Supercapacitors have attracted tremendous research interest, since they are expected to achieve battery-level energy density, while having a long calendar life and short charging time. Herein, a novel asymmetric supercapacitor has been successfully assembled from NiCo₂ S₄ nanosheets and spinous Fe₂ O₃ nanowire modified hollow melamine foam decorated with polypyrrole as positive and negative electrodes, respectively. Owing to the well-designed nanostructure and suitable matching of electrode materials, the assembled asymmetric supercapacitor (ASC) exhibits an extended operation voltage window of 1.6 V with an energy density of 20.1 Wh kg^-1 at a power density of 159.4 kW kg^-1 . Moreover, the ASC shows stable cycling stability, with 81.3 % retention after 4000 cycles and a low internal resistance of 1.03 Ω. Additionally, a 2.5 V light-emitting diode indicator can be lit up by three ASCs connected in series; this provides evidence of the practical application potential of the assembled energy-storage system. The excellent electrochemical performances should be credited to the significant enhancement of the specific surface area, charge transport, and mechanical stability resulting from the unique 3D morphology.

Rational design of multiple Prussian-blue analogues/NF composites for high-performance surpercapacitors

Multiple Prussian-blue analogues/NF composites were successfully fabricated through a one-pot chemical etching and growing process. The target materials NiCo_xFe_1−x-PBA/NF exhibited excellent electrochemical performance.

Configuring Optimal FeS2@Carbon Nanoreactor Anodes: Toward Insights into Pyrite Phase Change/Failure Mechanism in Rechargeable Ni-Fe Cells

Pyrite FeS₂ has long been a research focus as the alternative anode of rechargeable Ni-Fe cells owing to its eye-catching merits of great earth-abundance, attractive electrical conductivity, and output capacity. However, its further progress is impeded by unsatisfactory cyclic behaviors due to still "ill-defined" phase changes. To gain insights into the pyrite working principles/failure factors, we herein design a core-shell hybrid of a FeS₂@carbon nanoreactor, an optimal anode configuration approaching the practical usage state. The resultant electrodes exhibit a Max. specific capacity of ∼272.89 mAh g^-1 (at ∼0.81 A g^-1), remarkably improved cyclic longevity/stability (beyond ∼80% capacity retention after 10³ cycles) and superior rate capability (∼146.18 mAh g^-1 is remained at ∼20.01 A g^-1) in contrast to bare FeS₂ counterparts. The as-built Ni-Fe full cells can also output impressive specific energy/power densities of ∼87.38 Wh kg^-1/ ∼ 11.54 kW kg^-1. Moreover, a refreshed redox reaction working mechanism of "FeS₂OH ↔FeS₂↔Fe⁰_{(in pyrite domains)}" is redefined based on real-time electrode characterizations at distinct operation stages. In a total cyclic period, the configured pyrite-based anodes would stepwise undergo three critical stages nominally named "retention", "phase transition/coexistence", and "degradation", each of which is closely related to variations on anodic compositions/structures. Combined with optimal electrode configurations and in-depth clarifications on inherent phase conversions, this focus study may guide us to maximize the utilization efficiency of pyrite for all other aqueous electrochemical devices.

High Energy Capacitors Based on All Metal-Organic Frameworks Derivatives and Solar-Charging Station Application

High energy and efficient solar charging stations using electrochemical capacitors (ECs) are a promising portable power source for the future. In this work, two kinds of metal-organic framework (MOF) derivatives, NiO/Co₃ O₄ microcubes and Fe₂ O₃ microleaves, are prepared via thermal treatment and assembled into electrochemical capacitors, which deliver a relatively high specific energy density of 46 Wh kg^-1 at 690 W kg^-1 . In addition, a solar-charging power system consisting of the electrochemical capacitors and monocrystalline silicon plates is fabricated and a motor fan or 25 LEDs for 5 and 30 min, respectively, is powered. This work not only adds two novel materials to the growing categories of MOF-derived advanced materials, but also successfully achieves an efficient solar-ECs system for the first time based on all MOF derivatives, which has a certain reference for developing efficient solar-charge systems.

Synthesis of rose-like ZnAl-LDH and its application in zinc-nickel secondary battery

Rose-like zinc-aluminum hydrotalcite (ZnAl-LDH) was synthesized in an organic/water mixed solvent system by a simple hydrothermal method and applied to zinc-nickel secondary battery, and its electrochemical performance as a negative electrode active material was also studied. Rose-like ZnAl-LDH has the characteristic diffraction peaks of ZnAl-LDH. SEM and TEM results show that the rose-like ZnAl-LDH was assembled by LDH nanosheets with the center as the axis and inclined at certain angles to form a rose-like structure. Through cyclic voltammetry, EIS and galvanostatic charge and discharge tests, rose-like ZnAl-LDH is superior to the coprecipitation synthesized flake-like ZnAl-LDH in cycle stability and discharge capacity. The initial discharge specific capacity of rose-like ZnAl-LDH is 363.4 mAh g^-1, after 1250 cycles, the specific discharge capacity was 366.848 mAh g^-1, the average discharge specific capacity was 392.455 mAh g^-1 during the entire charge/discharge process. The results show that the rose-like ZnAl-LDH is a promising material with good cycle stability and high specific discharge capacity for energy storage devices.

Toward a high performance asymmetric hybrid capacitor by electrode optimization

Molybdenum disulfide (MoS₂) is an extremely promising electrode material for supercapacitors due to its superior electrochemical performance and conductivity.

Carbon-incorporated NiO/Co3O4 concave surface microcubes derived from a MOF precursor for overall water splitting

Carbon-incorporated NiO/Co₃O₄ concave surface microcubes (denoted as NCMC) are successfully developed from a precursor of Ni₃[Co(CN)₆]₂ for the first time.

Urchin-like NiO-NiCo2O4 heterostructure microsphere catalysts for enhanced rechargeable non-aqueous Li-O2 batteries

Urchin-like NiO-NiCo2O4 microspheres with heterostructures were successfully synthesized through a facile hydrothermal method, followed by thermal treatment. The unique structure of NiO-NiCo2O4 with the synergetic effect between NiCo2O4 and NiO, and the heterostructure favour the catalytic activity towards Li-O2 batteries. NiCo2O4 is helpful for boosting both the oxygen reduction reaction and oxygen evolution reaction for the Li-O2 batteries and NiO is likely to promote the decomposition of certain by-products. The special urchin-like morphology facilitates the continuous oxygen flow and accommodates Li2O2. Moreover, benefitting from the heterostructure, NiO-NiCo2O4 microspheres are able to promote the transport of Li ions and electrons to further improve battery performance. Li-O2 batteries utilizing a NiO-NiCo2O4 microsphere electrode show a much higher specific capacity and a lower overpotential than those with a Super P electrode. Moreover, they exhibit an enhanced cycling stability. The electrode can be continuously discharged and charged without obvious terminal voltage variation for 80 cycles, as the discharge capacity is restricted at 600 mA h g-1, suggesting that NiO-NiCo2O4 is a promising catalyst for Li-O2 batteries.

Hierarchical Nanosheet-Built CoNi2S4 Nanotubes Coupled with Carbon-Encapsulated Carbon Nanotubes@Fe2O3 Composites toward High-Performance Aqueous Hybrid Supercapacitor Devices

A hybrid supercapacitor system was designed with ternary Ni-Co sulfides (CoNi₂S₄) as cathode materials and Fe-based composites [carbon nanotubes (CNTs)@Fe₂O₃@C] as anode materials to achieve excellent overall electrochemical performance with high energy and power density as well as long lifespan. Here, hierarchical CoNi₂S₄ nanotubes were synthesized by a solvothermal route followed by sulfidation reaction for the first time, in which nanotubes were composed of interconnected ultrathin nanosheets. Consequently, such a unique nanosheet-built nanoarchitecture enables the CoNi₂S₄ cathode with multidimensional synergistic effect from one-dimensional nanotubes, two-dimensional nanosheets, and three-dimensional frameworks. Profiting from its structural merits, the as-prepared CoNi₂S₄ nanotubes deliver a high capacitance of 2552 F g^-1 at 1 A g^-1 with a high rate capacity of 81% at 25 A g^-1. In addition, the CNTs@Fe₂O₃@C anode materials-incorporating carbon-encapsulated ultrafine Fe₂O₃ nanoparticles into CNT matrices-were achieved by atomic layer deposition and acetylene thermal decomposition, which realize excellent electrochemical properties (678 F g^-1 at 1 A g^-1 and capacity retention of 82% at 25 A g^-1) that matched well with CoNi₂S₄ cathode materials. With the well-designed nanostructure and matching of materials and properties, the corresponding aqueous hybrid device exhibits a wide output voltage window of 0-1.75 V with a maximum energy density of 90.5 W h kg^-1 at a power density of 1.84 kW kg^-1. Meanwhile, a high energy density of 73.1 W h kg^-1 can be retained at an ultrahigh power density of 26.9 kW kg^-1. Moreover, the hybrid device has a stable cycling ability with 82.1% retention over 5000 cycles. This coordinative design strategy integrating the cathode and anode electrodes developed in this work provides a novel way to manufacture next-generation energy-storage device with high performance and safety.

Green synthesis of silver nanoparticles using Piper nigrum: tissue-specific bioaccumulation, histopathology, and oxidative stress responses in Indian major carp Labeo rohita

The aim of the present investigation is to assess the sublethal toxicity of biologically synthesized silver nanoparticles (Ag NPs) in Indian major carp Labeo rohita. Ag NPs used in the study were synthesized by using AgNO₃ with aqueous leaf extract of Piper nigrum. Median lethal concentration (LC₅₀) of synthesized Ag NPs was determined for 96 h (25 μg/L); 2.5 μg/L (1/10th LC₅₀) and 5 μg/L (1/5th LC₅₀) were taken as sublethal concentrations to evaluate the toxicity for 35 days. The results of the TEM, SEM, and EDX analyses revealed that Ag NPs were considerably accumulated in the gill, liver, and kidney of fish at both concentrations (2.5 and 5 μg/L). Consequently, the activity of the antioxidant enzymes, SOD and CAT, was significantly (P < 0.05) decreased in the gill, liver, and kidney when compared to the control group during the study period. However, lipid peroxidase (LPO) activity in the gill, liver, and kidney was significantly (P < 0.05) increased, and the result concluded a possible sign of free radical-induced oxidative stress in Ag NP-exposed fish than the sham-exposed individuals. The histopathological study also confirmed the alterations such as degeneration of lamella, lifting of lamellar epithelium, hepatic necrosis, pyknotic nuclei, increased intracellular space, and shrinkage of glomerulus elicited by Ag NPs in the gill, liver, and kidney of Labeo rohita with two different concentrations. The findings of the present study revealed that green synthesis of Ag NPs from Piper nigrum at sublethal concentrations leads to accumulation of Ag, oxidative stress, and histopathological alterations in the target organs of the fish, Labeo rohita.

Hierarchical FeS/RGO/FeS@Fe foil as high-performance negative electrode for asymmetric supercapacitors

A hierarchical FeS/RGO/FeS composite in situ grown on Fe foil was prepared, which exhibits excellent electrochemical performances in a supercapacitor.

NiO/NixCo3−xO4 porous ultrathin nanosheet/nanowire composite structures as high-performance supercapacitor electrodes

The demand for a new generation of high-safety, long-lifespan, and high-capacity power sources increases rapidly with the growth of energy consumption in the world. Here we report a facile method for preparing architecture materials made of NiO/Ni_xCo_3−xO₄ porous nanosheets coupled with NiO/Ni_xCo_3−xO₄ porous nanowires grown in situ on nickel foams using a hydrothermal method without any binder followed by a heat treatment process. The nanosheet-shaped NiO/Ni_xCo_3−xO₄ species in the nanosheet matrix function well as a scaffold and support for the dispersion of the Ni_xCo_3−xO₄ nanowires, resulting in a relatively loose and open structure within the electrode matrix. Among all composite electrodes prepared, the one annealed in air at 300 °C displays the best electrochemical behavior, achieving a specific capacitance of 270 mF cm⁻² at 5 mA cm⁻² while maintaining excellent stability (retaining ≈ 89% of the max capacitance after 20 000 cycles), demonstrating its potential for practical application in power storage devices.

Porous ultrathin nanosheet/nanowire composite structures are prepared as high-performance supercapacitor electrodes which exhibit excellent stability.

The interlocked in situ fabrication of graphene@prussian blue nanocomposite as high-performance supercapacitor

High-quality graphene@prussian blue (G@PB) nanocomposite sheets fabricated via the one-step in situ hydrothermal method show great promise for energy-storage hybrid electrodes with excellent electrochemical performance.

NiCo₂O₄-Based Supercapacitor Nanomaterials

In recent years, the research on supercapacitors has ushered in an explosive growth, which mainly focuses on seeking nano-/micro-materials with high energy and power densities. Herein, this review will be arranged from three aspects. We will summarize the controllable architectures of spinel NiCo₂O₄ fabricated by various approaches. Then, we introduce their performances as supercapacitors due to their excellent electrochemical performance, including superior electronic conductivity and electrochemical activity, together with the low cost and environmental friendliness. Finally, the review will be concluded with the perspectives on the future development of spinel NiCo₂O₄ utilized as the supercapacitor electrodes.

Enhanced performances of functionalized XC-72 supported Ni(OH)2 composites for supercapacitors

Introducing oxygen-containing groups on the surface of XC-72 improves the supercapacitive performances of Ni(OH)₂/XC-72.

An overview of AB2O4- and A2BO4-structured negative electrodes for advanced Li-ion batteries

Energy-storage devices are state-of-the-art devices with many potential technical and domestic applications.