Enhanced Electrodes for Supercapacitor Applications Prepared by Hydrothermal-Assisted Nano Sheet-Shaped MgCo2O4@ZnS

In this paper, we report on nanodisc-shaped MgCo2O4 wrapped with ZnS, achieved using the sol–gel-assisted hydrothermal method. This enhances the electrochemical performance, with the electrode delivering superior supercapacitive performance compared to MgCo2O4. Moreover, the nanodisc provides more active sites and allows smooth charge transfer during faradaic reactions. The nanodisc-shaped MgCo2O4 with ZnS delivers a capacitance of approximately 910 F/g at 1 A/g. The fabricated asymmetric capacitor is composed of MgCo2O4@ZnS and activated carbon (AC). The nanodisc-shaped MgCo2O4@ZnS provides more active sites and allows the smooth transport of electrons during long-term cycling. In addition, the electrode side reactions and electrolyte decomposition are significantly reduced due to the ZnS coating on the surface of the MgCo2O4, allowing this asymmetric capacitor to deliver an energy density of 43 Wh·kg−1 at 1454 W·kg−1. The performance of the asymmetric capacitor exhibits enhanced supercapacitive performance and opens a new way to investigate asymmetric supercapacitor devices.

New rationally designed hybrid polypyrrole@SnCoS4 as an efficient anode for lithium-ion batteries

Three active materials containing binary metal sulfide (SnCoS₄) were obtained via a simple hydrothermal method. Also, the electrochemical performance of the anode materials was investigated in a lithium-ion half-cell.

Nano spinel cobaltites and their catalytic and electrochemical properties: facile synthesis of metal (Co, Ni, and Zn) and mixed metal (Co–Ni and Co–Zn) complexes of Schiff bases prepared from α-ketoglutaric acid and ethyl carbazate

Nanocobaltites synthesized from solid solution precursors showed strong photocatalytic activity and enhanced electrochemical properties.

Synthesis of Hierarchical Porous Carbon in Molten Salt and Its Application for Dye Adsorption

Hierarchical porous carbon was successfully synthesized from glucose in a molten salt at 800 °C for 2 h. It was amorphous and contained numerous oxygen containing functional groups on its surface. The porous carbon with 1.0 wt% Fe(NO₃)₃·9H₂O oxidizing agent showed the highest specific surface area of 1078 m²/g, and the largest pore volume of 0.636 cm³/g, among all of the samples. Raman and TEM results revealed that it had more defects and pores than other as-prepared carbon materials. The adsorption capacities of as-prepared porous carbon for methylene blue (MB) and methyl orange (MO) were 506.8 mg/g and 683.8 mg/g, respectively. The adsorption isotherms fit the Langmuir model and the adsorption kinetics followed the pseudo-second-order kinetic model.

Target construction of Co3O4 with an improved layer structure for highly efficient Li-storage properties

An improved layered structure for the conversion-reaction-based anode material of Co₃O₄ is demonstrated, which displays highly efficient Li-storage properties.

High capacity MoO3/rGO nanocomposite anode for lithium ion batteries: an intuition into the conversion mechanism of MoO3

rGO wrapped MoO₃ NPs were successfully synthesized via simple and scalable steps as potential anode materials for Li-ion batteries.

K-ion and Na-ion storage performances of Co3O4-Fe2O3 nanoparticle-decorated super P carbon black prepared by a ball milling process

The hybridisation of Co₃O₄ and Fe₂O₃ nanoparticles dispersed in a super P carbon matrix is proposed as a favourable approach to improve the electrochemical performance (reversible capacity, cycling stability and rate capability) of the metal oxide electrodes in metal-ion batteries. Hybrid Co₃O₄-Fe₂O₃/C is prepared by a simple, cheap and easily scalable molten salt method combined with ball-milling and used in sodium-ion and potassium-ion batteries for the first time. The electrode exhibits excellent cycling stability and superior rate capability in sodium-ion cells with a capacity recovery of 440 mA h g^-1 (93% retention) after 180 long-term cycles at 50-1000 mA g^-1 and back to 50 mA g^-1. In contrast, Co₃O₄-Fe₂O₃, Co₃O₄ and Fe₂O₃ electrodes display unsatisfactory electrochemical performance. The hybrid Co₃O₄-Fe₂O₃/C is also reactive with potassium and capable of delivering a reversible capacity of 220 mA h g^-1 at 50 mA g^-1 which is comparable with the most reported anode materials for potassium-ion batteries. The obtained results broaden the range of transition metal oxide-based hybrids as potential anodes for K-ion and Na-ion batteries, and suggest that further studies of these materials with potassium and sodium are worthwhile.

Two isomorphous coordination polymer-derived metal oxides as high-performance anodes for lithium-ion batteries

Two Co₃O₄ and NiO anodes for LIBs derived from novel, isomorphous 2D coordination polymers displayed high rate cycling performance.

Mechanochemically induced transformation of CoO(OH) into Co3O4 nanoparticles and their highly reversible Li storage characteristics

A simple synthetic method for the mechanochemically induced transformation of cobalt oxyhydroxides (CoO(OH)) into cobalt oxide (Co₃O₄) nanoparticles is developed and applied to Li-ion batteries.

Electrospinning of Nanofibers for Energy Applications

With global concerns about the shortage of fossil fuels and environmental issues, the development of efficient and clean energy storage devices has been drastically accelerated. Nanofibers are used widely for energy storage devices due to their high surface areas and porosities. Electrospinning is a versatile and efficient fabrication method for nanofibers. In this review, we mainly focus on the application of electrospun nanofibers on energy storage, such as lithium batteries, fuel cells, dye-sensitized solar cells and supercapacitors. The structure and properties of nanofibers are also summarized systematically. The special morphology of nanofibers prepared by electrospinning is significant to the functional materials for energy storage.

Porous Iron Cobaltate Nanoneedles Array on Nickel Foam as Anode Materials for Lithium-Ion Batteries with Enhanced Electrochemical Performance

A monocrystalline and porous FeCo2O4 nanoneedles array growing directly on a nickel foam substrate was obtained by a hydrothermal technique accompanying with combustion of the one-dimensional precursor. The average length of the FeCo2O4 nanoneedles is approximately 2 μm, while the diameter of the root segment of the nanoneedle can be estimated to be around 100 nm, which gradually reduces to only several nanometers at the top. When the as-prepared porous FeCo2O4 nanoneedles array with a high surface area of 58.49 m(2) g(-1) was applied as binder-free electrode in lithium-ion batteries, it exhibited satisfactory electrochemical performance, such as outstanding reversibility (Coulombic efficiency of approximately 92-95%), high specific capacity (1962 mAh g(-1) at the current density of 100 mA g(-1)), and excellent rate performance (discharge capacity of 875 mAh g(-1) at the current density of 2000 mA g(-1)), due to the various favorable conditions. Undoubtedly, the simple but effective strategy can be expanded to other high-performance binary metal-oxide materials.

Co2Mo3O8/reduced graphene oxide composite: synthesis, characterization, and its role as a prospective anode material in lithium ion batteries

Easy solid state synthesis of Co₂Mo₃O₈/reduced graphene oxide composite which exhibited a very high specific capacity (∼954 mA h g⁻¹) when tested as an anode material in lithium ion batteries.

Designed construction and validation of carbon-free porous MnO spheres with hybrid architecture as anodes for lithium-ion batteries

A simple, cost-effective solution mediated oxidation strategy requiring no compositing additive has been used to engineer hierarchically formed carbon-free porous MnO spheres, validated as high capacity and high rate lithium-ion battery anode.

Facile and Eco-Friendly Synthesis of Finger-Like Co₃O₄ Nanorods for Electrochemical Energy Storage

Co₃O₄ nanorods were prepared by a facile hydrothermal method. Eco-friendly deionized water rather than organic solvent was used as the hydrothermal media. The as-prepared Co₃O₄ nanorods are composed of many nanoparticles of 30–50 nm in diameter, forming a finger-like morphology. The Co₃O₄ electrode shows a specific capacitance of 265 F g⁻¹ at 2 mV s⁻¹ in a supercapacitor and delivers an initial specific discharge capacity as high as 1171 mAh g⁻¹ at a current density of 50 mA g⁻¹ in a lithium ion battery. Excellent cycling stability and electrochemical reversibility of the Co₃O₄ electrode were also obtained.

Effect of zinc : cobalt composition in ZnCo2O4 spinels for highly selective liquefied petroleum gas sensing at low and high temperatures

Nano ZnCo₂O₄ spinels were synthesized at varying zinc and cobalt ratios such as 1 : 1, 1 : 1.5, 1 : 2, 1 : 2.5 and 1 : 3.

One-step calcination-free synthesis of multicomponent spinel assembled microspheres for high-performance anodes of li-ion batteries: a case study of MnCo(2)O(4)

Multicomponent spinel metal-oxide assembled mesoporous microspheres, promising anode materials for Li-ion batteries with superior electrochemical performance, are usually obtained using different kinds of precursors followed by high-temperature post-treatments. Nevertheless, high-temperature calcinations often cause primary particles to aggregate and coarsen, which may damage the assembled microsphere architectures, leading to deterioration of electrochemical performance. In this work, binary spinel metal-oxide assembled mesoporous microspheres MnCo2O4 were fabricated by one-step low-temperature solvothermal method through handily utilizing the redox reaction of nitrate and ethanol. This preparation method is calcination-free, and the resulting MnCo2O4 microspheres were surprisingly assembled by nanoparticles and nanosheets. Two kinds of MnCo2O4 crystal nucleus with different exposed facet of (1̅10) and (11̅2̅) could be responsible for the formation of particle-assembled and sheet-assembled microspheres, respectively. Profiting from the self-assembly structure with mesoporous features, MnCo2O4 microspheres delivered a high reversible capacity up to 722 mAh/g after 25 cycles at a current density of 200 mA/g and capacities up to 553 and 320 mAh/g after 200 cycles at a higher current density of 400 and 900 mA/g, respectively. Even at an extremely high current density of 2700 mA/g, the electrode still delivered a capacity of 403 mAh/g after cycling with the stepwise increase of current densities. The preparation method reported herein may provide hints for obtaining various advanced multicomponent spinel metal-oxide assembled microspheres such as CoMn2O4, ZnMn2O4, ZnCo2O4, and so on, for high-performance energy storage and conversion devices.

Li storage and impedance spectroscopy studies on Co3O4, CoO, and CoN for Li-ion batteries

The compounds, CoN, CoO, and Co3O4 were prepared in the form of nano-rod/particles and we investigated the Li-cycling properties, and their use as an anode material. The urea combustion method, nitridation, and carbothermal reduction methods were adopted to prepare Co3O4, CoN, and CoO, respectively. X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), and the Brunauer-Emmett-Teller (BET) surface and density methods were used to characterise the materials. Cyclic voltammetry (CV) was performed and galvanostatic cycling tests were also conducted up to 60-70 cycles. The observed reversible capacity of all compounds is of the increasing order CoO, Co3O4, CoN and all compounds showed negligible capacity fading. CoO allows for Li2O and Co metal to form during the discharge cycle, allowing for a high theoretical capacity of 715 mA h g(-1). Co3O4 allows for 4 Li2O and 3Co to form, and has a theoretical capacity of 890 mAhg(-1). CoN is the best anode material of the three because the nitrogen allows for Li3N and Co to form, resulting in an even higher theoretical capacity of 1100 mAhg(-1) due to the Li3N and Co metal formation. Irrespective of morphology the charge profiles of all three compounds showed a major plateaux ~2.0 V vs. Li and potential values are almost unchanged irrespective of crystal structure. Electrochemical impedance spectroscopy (EIS) was performed to understand variation resistance and capacitance values.

Hierarchical porous Co3O4 nanosheet arrays directly grown on carbon cloth by an electrochemical route for high performance Li-ion batteries

Co₃O₄ nanosheet arrays were grown on carbon cloth homogeneously; excellent electrochemical performance was obtained due to the unique structure and morphology.

Molten salt synthesis of tin doped hematite nanodiscs and their enhanced electrochemical performance for Li-ion batteries

Sn⁴⁺ doped α-Fe₂O₃ nanodiscs with good lithium storage properties have been prepared by a molten salt method.

Template-free synthesis of amorphous double-shelled zinc-cobalt citrate hollow microspheres and their transformation to crystalline ZnCo2O4 microspheres

A novel and facile approach was developed for the fabrication of amorphous double-shelled zinc-cobalt citrate hollow microspheres and crystalline double-shelled ZnCo2O4 hollow microspheres. In this approach, amorphous double-shelled zinc-cobalt citrate hollow microspheres were prepared through a simple route and with an aging process at 70 °C. The combining inward and outward Ostwald ripening processes are adopted to account for the formation of these double-shelled architectures. The double-shelled ZnCo2O4 hollow microspheres can be prepared via the perfect morphology inheritance of the double-shelled zinc-cobalt citrate hollow microspheres, by calcination at 500 °C for 2 h. The resultant double-shelled ZnCo2O4 hollow microspheres manifest a large reversible capacity, superior cycling stability, and good rate capability.

Li-cycling properties of molten salt method prepared nano/submicrometer and micrometer-sized CuO for lithium batteries

We report the synthesis of CuO material by molten salt method at a temperature range, 280 to 950 °C for 3 h in air. This report includes studies on the effect of morphology, crystal structure and electrochemical properties of CuO prepared at different temperatures. Obtained CuO was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) surface area methods. Samples prepared at ≥410 °C showed a single-phase material with a lattice parameter value of a = 4.69 Å, b = 3.43 Å, c = 5.13 Å and surface area values are in the range 1.0-17.0 m(2) g(-1). Electrochemical properties were evaluated via cyclic voltammetry (CV) and galvanostatic cycling studies. CV studies showed a minor difference in the peak potentials depending on preparation temperature and all compounds exhibit a main anodic peak at ~2.45 V and cathodic peaks at ~0.85 V and ~1.25 V vs Li. CuO prepared at 750 °C showed high and stable capacity of ~620 mA h g(-1) at the end of 40th cycle.