Improvement of Electrochemical Properties of Poly(3,4-ethylene dioxythiophene) (PEDOT) Thin Film by UV Irradiation

Electrochemical redox supercapcitor is one of promising rechargeable power sources for portable electronic, display or telecommunication devices since it has a large energy density, very fast charge/discharge time and long life cycle. In this study, poly(3,4-ethylene dioxythiophene) (PEDOT) thin film as the electrode of electrochemical supercapacitor was deposited on a metal current collector by in-situ polymerization method. Symmetrical electrochemical capacitor was then assembled using PEDOT films as working and counter electrodes, where 0.1 M lithium perchlorate (LiClO4) solution in acetonitrile was used as the electrolyte solution. Typical specific discharge capacitance of the capacitor was about 70 F/g and showed little decrease after 1,000 charge/discharge cycles. We also found that UV irradiation improved the electrochemical properties of redox capacitor by formation of hydrophilic polar groups on PEDOT film surface. After UV irradiation on the surface of PEDOT film for 2 hours with the intensity of 30 mW/cm2, the specific discharge capacitance increased by about 10% compared to capacitance of pristine PEDOT film.

Numerical Investigation on the Effects of Circuit Parameters on the Plastic Deformation of Fastener Holes in Thin Aluminum Alloy via Electromagnetic Expansion Process

The size of plastic deformation zone during fastener hole strengthening is a critical indicator of the strengthening effect. In this study, a considerable plastic deformation zone in 1.5 mm aluminum alloy plate with a hole was produced via electromagnetic strengthening. The finite element analysis results showed that the electromagnetic strengthening process could achieve high compressive hoop residual stress around the fastener hole in thin plate without serious axial deformation compared with conventional cold hole expansion process. The simulation results were experimentally validated by the grid method. Furthermore, for the same discharge energy, the size of plastic deformation zone varies with the discharge capacitance, and there was an optimal combination of the discharge capacitance and discharge voltage. What’s more, even the plastic deformation zone was the same at the maxed load, different unloading process during the electromagnetic hole expansion process also had a great influence on the strengthening effect.

Dependence of Capacitive Properties of an EDLC on Exfoliation Time of Graphite Electrodes

The scientific focus has been directed through the production and application of ‘wonder material- graphene’ after its discovery in 2004. But the mass production cost has become a huge disadvantage towards commercializing graphene based manufactures. As alternative low cost material, exfoliated graphite (EG) has emerged to be a novel nanostructured carbon material with a potential for electrochemical energy storage device applications owed to its unique characteristics similar to graphene. In this study a series of EG samples were prepared by a surfactant mediated liquid phase exfoliation method by changing the exfoliation time. Electrochemical double layer capacitors (EDLCs) were fabricated using different EG samples as an electrode material and a gel polymer electrolyte (GPE). They were characterized by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and galvanostatic charge discharge (GCD) techniques. EDLC having EG electrodes of 10 h exfoliation time showed the highest results with single electrode specific capacitance (Csc) of 4.12 F g− 1, single electrode specific discharge capacitance (Csd) of 1.10 F g− 1 and relaxation time of 0.22 s from CV, GCD and EIS respectively.

Effect of the Anionic Counterpart: Molybdate vs. Tungstate in Energy Storage for Pseudo-Capacitor Applications

Nickel-based bimetallic oxides (BMOs) have shown significant potential in battery-type electrodes for pseudo-capacitors given their ability to facilitate redox reactions. In this work, two bimetallic oxides, NiMoO4 and NiWO4, were synthesized using a wet chemical route. The structure and electrochemical properties of the pseudo-capacitor cathode materials were characterized. NiMoO4 showed superior charge storage performance in comparison to NiWO4, exhibiting a discharge capacitance of 124 and 77 F.g−1, respectively. NiMoO4, moreover, demonstrates better capacity retention after 1000 cycles with 87.14% compared to 82.22% for NiWO4. The lower electrochemical performance of the latter was identified to result from the redox behavior during cycling. NiWO4 reacts in the alkaline solution and forms a passivation layer composed of WO3 on the electrode, while in contrast, the redox behavior of NiMoO4 is fully reversible.

Preliminary Study on the Performance of a Redox Capacitor with the use of Ionic Liquid-based Gel Polymer Electrolyte and Polypyrrole Electrodes

Redox capacitor, which is one type of supercapacitor, has been attracted tremendously as they show a satisfactory specific capacitance, good cycle ability, and good stability. The present study reveals a redox capacitor fabricated with an ionic liquid (IL) based gel polymer electrolyte (GPE). Electrodes of the redox capacitor were fabricated with the conducting polymer, polypyrrole (PPy). The composition of the GPE was polyvinylidenefluoride-co-hexafluoropropylene (PVdF-co-HFP) : 1-ethyl-3-methylimidazolium trifluoromethanesulfonate (1E3MITF) : ZnTF. Characterization of redox capacitor was done by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and galvanostatic charge-discharge (GCD) tests. The relaxation time constant (τ0) of the redox capacitor is about 31.57 s implying somewhat fast redox reactions. Initial single electrode specific capacitance (CSC) was 150.16 Fg-1 and at the 500th cycle, it was 40.03 Fg-1. The decrease of the CSC may be due to the formation of the passivation layer at the GPE / electrode interface resulting in degradation upon cycling. The GCD test resulted 48.40 Fg-1 of initial single electrode specific discharge capacitance (Csd) value. Upon 1000 cycles, it was reached 22.25 Fg-1. The decrease of Csd may be due to the degradation of the electrode and the IL-based GPE upon prolonged cycling.

Investigation of Electromagnetic Pulse Compaction on Conducting Graphene/PEKK Composite Powder

Polymer-composite materials have the characteristics of light weight, high load, corrosion resistance, heat resistance, and high oil resistance. In particular, graphene composite has better electrical conductivity and mechanical performance. However, the raw materials of graphene composite are processed into semi-finished products, directly affecting their performance and service life. The electromagnetic pulse compaction was initially studied to get the product Graphene/PEKK composite powder. Simultaneously, spark plasma sintering was used to get the bars to determine the electrical conductivity of Graphene/PEKK composite. On the basis of this result, conducting Graphene/PEKK composite powder can be processed by electromagnetic pulse compaction. Finite element numerical analysis was used to obtain process parameters during the electromagnetic pulse compaction. The results show that discharge voltage and discharge capacitance influence on the magnetic force, which is a main moulding factor affecting stress, strain and density distribution on the specimen during electromagnetic pulse compaction in a few microseconds.

N and S co-doped graphene enfolded Ni–Co-layered double hydroxides: an excellent electrode material for high-performance energy storage devices

A novel graphene embedded Ni–Co-LDH electrode was developed. The charge transportation rate was enhanced via N and S heteroatom doping, which results in an excellent discharge capacitance of 2193 F g−1 at 5 A g−1.

Studying the effect of electrohydraulically treated soil solutions on plant growth and development

Increasing agricultural production is an important food task. In providing plants with the necessary nutrients, it is necessary to intensify by applying fertilizers or using alternative environmentally friendly methods. These include technologies that allow the conversion of nutrients into a form accessible to plants, and electrophysical technologies using high-voltage pulse discharge. This article describes the installation for creating electrohydraulic shocks. The experimental studies on the justification of the parameters of electro-hydraulic treatment of solutions and the study of the effect of treatment by solutions treated with electro-hydraulic shock on the development of crops using the example of tomato resulted in obtaining the optimal process technological parameters of the installation. They are voltage – 30 kV, discharge capacitance of the capacitor – 0.6 μF, number of pulses – 200.

PREPARATION AND CHARACTERIZATION OF GO/ZnO ELECTRODE FOR SUPERCAPACITORS

In this paper, zinc oxide (ZnO) nanoparticles were prepared by solvothermal method. A mixture of ZnO nanoparticles and GO, surfactants, binders are dispersed in aqueous solvent. This suspension was then used as the ink for the modified 3d printer to coat on the graphite substrate to form electrodes. The GO/ZnO film has a specific capacitance of 119.9 F/g at a scan rate of 5 mV/s of CV test. The specific discharge capacitance was 153.9 F/g and retained 94.5% after 3000 cycles of galvanostatic charge-discharge (GCD) measurement with a current density of 15 mA/cm2.

Preparation and Characterization of Electrospun Gelatin Nanofibers for Use as Nonaqueous Electrolyte in Electric Double-Layer Capacitor

A novel nanofibrous gel electrolyte was prepared via gelatin electrospinning for use as a nonaqueous electrolyte in electric double-layer capacitors (EDLCs). An electrospinning technique with a 25 wt% gelatin solution was applied to produce gelatin electrospun (GES) nanofiber electrolytes. Structural analysis of the GES products showed a clearly nanofibrous structure with fiber diameters in the 306.2–428.4 nm range and exhibiting high thermal stability, high tensile strength, and a stable form of nanofibrous structure after immersion in 1-ethyl-3-methylimidazolium tetrafluoroborate (EMImBF4). After testing over a range of spinning times, GES electrolytes that were produced at 25 min (GES-25) had a suitable thickness for the assembly of EDLC with the optimized tensile properties and were used to fabricate EDLC test cells with EMImBF4. These test cells were compared to those with pure EMImBF4 and a separator as an electrolyte. The electrochemical properties of the test cells were characterized by charge-discharge testing, discharge capacitance, and alternative current (AC) impedance measurements. AC impedance measurements showed that the test cell with the GES-25/EMImBF4 gel electrolyte showed slightly poorer contact with the electrode when compared to that with pure EMImBF4, whereas exhibited comparable IR drop and discharge capacitance (calculated capacitance retention was 56.6%). The results demonstrated that this novel gel electrolyte can be used as a nonaqueous electrolyte in order to improve the safety in EDLCs.