Lithium-oxygen (Li-O2) battery is considered the system with the highest theoretical Specific energy density among all other energy storage devices. Therefore, it can be a suitable response to the increasing demand for the energy. Due to the fact that the cathode is one the of key components, this research represents a practical investigation on the impact of utilizing molybdenum disulfide as an electrocatalyst in the cathode on Specific capacitance of Li-O2 battery. To do so, at the first step, graphite/MoS2 composite was synthesized via one-pot hydrothermal approach. Then, different analysis of X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectrometer (FTIR), N2 adsorption-desorption, and scanning electron microscopy (SEM) were applied to study phase characteristics, covalent bonds, porous structure, and to observe the surface morphology of the synthesized composite. Finally, it was employed as the cathode of the Li-O2 battery and could exhibit the Specific capacitance of 912 mA h g-1, which illustrates the significant effect of using MoS2 on increasing the Specific capacitance by about 17.5 times than the sample without it.

Electrochemical supercapacitors store energy in the electric field formed at the interface of electrode/electrolyte in the electrochemical double layer. Compared to conventional capacitors, using high surface area electrodes results in the extremely large capacitance in supercapacitors. A mathematical model has been developed to investigate the effect of electrode thickness and porosity on the performance of double-layer supercapacitor. The model is based on the conservation of species and charge governing equations. This model drops the common simplifying assumptions of concentrations uniformity and capacitance independence of voltage in supercapacitors models. The model can predict the experimental data of cell voltage with high accuracy and is used to examine the effect of utilizing different electrode thicknesses and porosities on the performance. In the design and operation condition of supercapacitor considered here, Specific capacitance increases as electrode thickness increases for electrode thicknesses from 70 to 90 micrometer and decreases as electrode thickness exceeds 90 micrometer. Employing more porous electrodes enhances Specific capacitance. The amount of increment is such that if the electrode porosity is doubled, Specific capacitance increases byapproximately 5%.

Polyaniline was synthesized chemically. The purified form of polyaniline was swollen with THF before dispersing in N-methyl pyrrolidone for film making. The thickness of the films were 80 and 100 micrometers. Polyaniline films were doped with hydrochloric acid at two different concentrations for varied periods of time. The doped films with areas of 1 cm2 were used as conducting plates, and papers were soaked with paraffin as dielectric of conducting polyaniline capacitor. In the present work design, construction of capacitor based on conducting polyaniline films has been investigated experimentally. The results of measurement and calculation of capacitance of the designed capacitor, assuming that diffusion of dopant in polyaniline is plate-like, arc reported. Stability under both atmospheric and vacuum conditions were investigated. Experimental results and theoretical studies show that by increasing the doping time, capacitance is increased. Also, the thinner insulating form of polyaniline film, the faster the two conducting fronts meet and the capacitor reaches a maximum. The value of this maximum in the present work was 42PF.

To prevent a potential energy crisis in the near future, it is necessary to develop high-performance energy storage devices, such as supercapacitors (SCs). In this study, we fabricated a thin film of a new redox catalyst, catocene, on a carbon microfiber electrode (Cat/CMF) using a self-assembled method. We then investigated its electrochemical behaviour in an aqueous sodium sulfate electrolyte. Different techniques were used to evaluate the surface quality of the thin film and its iron content, including scanning electron microscopy (SEM), laser-induced breakdown spectroscopy (LIBS), and attenuated total reflection infrared spectroscopy (ATR). The efficiency and Specific capacity of the electrodes were then assessed using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge-discharge (GCD) methods in a three-electrode system. Electrochemical tests revealed that the redox processes are diffusion-controlled, exhibiting battery-like behaviour. The cathodic transfer coefficient is close to 0.48, and the charge transfer resistance of the modified electrode is improved up to 23 times compared to the bare electrode. At a current density of 0.55 A/g, the Specific capacity of the Cat/CMF electrode is 39.76 F/g. At a current density of 0.83 A/g, the catocene thin film exhibits a supercapacitance behaviour with an energy density of 2.5 Wh/kg and a power density of 373.8 W/kg.

The graphene (GR) has attracted intensive interest due to its two-dimensional and unique physical properties. In the present study, the graphene sheets were synthesized by electrochemical exfoliation of graphite in sulfuric acid solution. The polybithiophene-graphene (PbTh-GR) composite films deposited onto indium tin oxide substrate (ITO/PbTh-GR) have been prepared by the incorporation of graphene sheets into the PbTh matrix during electropolymerization under magnetic stirring from the LiClO4/CH3CN electrolyte containing the bithiophene (bTh) monomer and graphene sheets. The incorporation of graphene sheets at different masses (1, 2 and 3 mg) is ensured by the effect of the stirring of the electrolyte. The characterisation of films is effected by electrochemical methods (cyclic voltammetry and impedance spectroscopy), spectroscopic technics (FT-IR, UV-Visible), X ray diffraction, thermogravimetric analysis, and scanning electron microscopy. It was observed that the electrochemical performance measurements of the ITO/PbTh-GR (3 mg) film show a Specific capacity of around 65 F/g, which is six times higher than that of ITO/PbTh films, 11 F/g.

Spinel magnesium Cobaltite (MgCo2O4) nanoparticles with a crystalline size in the range of ∼ 16 nm were prepared by a simple co-precipitation technique with NaOH as a precipitant. The formation of spinel MgCo2O4 phase was confirmed by X-ray diffraction (XRD) pattern. Scanning electron microscope (SEM) images showed that aggregated nanoplates. The electrochemical performance of modified MgCo2O4 electrodes was investigated with 2M of tetrabutylammonium perchlorate (TBA) electrolyte. The cyclic voltammetry (CV) results revealed that the MgCo2O4 electrode reached the highest Specific capacitance of 390 ° F/g at a scan rate of 5mV/s. The excellent electrochemical performance was absorbed due to the electrochemical faradaic redox reactions related to the intercalation/de-intercalation of the tetrabutylammonium cation (TBA+) and MgCo2O4 lattice, and brings an additional pseudocapacitive contribution. The present work proves that the prepared magnesium cobaltite can serve as advanced electrode material for next generation organic electrolyte supercapacitors.