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In this study, synthesis of TiS2 nanoflakes is reported using a home-made CVD furnace. With vaporing sulfur powder in this system, TiS2 nanosheets were grown directly on the Ti powder. The application of these nanoflakes as a possible cathode material for sodium-ion battery has also been investigated. The prepared nanosheets were formed in highly packed clusters with a typical width of around 30 nm and height of 2 µm. The interlayer space between the nanoflakes can provide facile access path for intercalation of sodium ions. The synthesized TiS2 nanoflakes have been implemented for the fabrication of sodium-ion battery cathode electrode, using a 8:1:1 weight ratio of active material:C65: PVDF for slurry preparation, followed by coating on an aluminum current collector. The prepared electrode exhibits an initial reversible capacity (2nd cycle) of 114 mAh g−1 at current density of 66.7 mAg−1. It also showed remarkable coulombic efficiency of 99% after 100 cycles. It also showed superb cycling stability by only 7% decay after 100 cycles. These nanosheets are proposed as a high-performance cathode material for sodium-ion battery. [ABSTRACT FROM AUTHOR]

Graphene-based supercapacitors demonstrate extraordinary energy storage capacity due to their layered structure, large effective surface area, high electrical conductivity and acceptable chemical stability. Herein, reduced graphene oxide (rGO)-based supercapacitors were introduced in a simple, and fast method with considerable performance. For this purpose, graphene oxide (GO) was synthesized by the modified Hummers' method and then easily reduced to desired patterns of rGO using a commercial LightScribe DVD drive. In order to increase the effective surface area, as well as the electrical conductivity of rGO layers, oxygen/sulfur hexafluoride plasma was applied to the rGO followed by laser irradiation. By performing such sequential processes, an rGO-based supercapacitor was introduced with a capacitance of about 10.2 F/cm3, which had high stability for more than 1000 consecutive charge–discharge cycles. The fabrication steps of the electrodes were investigated by different analyses such as SEM, TEM, Raman, surface resistance, BET, and XPS measurements. Results showed that these rGO-based electrodes fabricated by sequential processes are very interesting for practical applications of energy storage. [ABSTRACT FROM AUTHOR]

In this paper, we have developed an inexpensive and simple method to realize high performance supercapacitor with high specific capacitance of 21 mF/cm2 at a scan rate of 10 mV/s, which is among the highest areal capacitance values reported for SnO2 based devices. Stainless steel foils, coated with a mixture of tin oxide (sol-gel) and multiwall carbon nanotube powder to act as the working electrode, have been employed as substrates for the fabrication of these supercapacitors. The use of hydrogen plasma at a moderate temperature of 300-600 °C has been found to be suitable to functionalize the tin-oxide layer and to incorporate deep porosity in its structure. The application of carbon nanotubes has been a critical step to improve the capacitance of the device and to add to its cycling stability. Comparing the results of tin-oxide with CNT-incorporated structures demonstrates more than two orders of magnitude improvement in the value of areal capacitance. The films have been analyzed using scanning and transmission electron microscopy, X-ray diffraction, and Raman spectroscopy. The electrochemical properties of the electrodes have been examined using the cyclic voltammetry and galvanostatic measurements. [ABSTRACT FROM AUTHOR]

In this study, the electrochemical performance of the binder-free electrode based on the reinforced resorcinol formaldehyde (RF) carbon aerogels (CAs) was investigated for electric double layer capacitor (EDLC) application. Resorcinol formaldehyde aerogel (RF) was crosslinked using methylene diphenyl diisocyanate (MDI) and then pyrolyzed to produce carbon aerogel (CA). CA was subsequently activated using CO2 gas. The morphological changes due to the reinforcing and activation process were explored by SEM. The BET and BJH results showed an improvement in specific surface area and microporous volume. The CO2-activated CAs displayed up to twice more specific surface areas compared with the unactivated CAs. The compressive test verified an improvement of up to 5 times in the mechanical strength. In order to investigate the electrochemical performance, cyclic voltammetry (CV), charge/discharge (CD), and electrochemical impedance microscopy (EIS) were carried out. In an identical electrode weight, the specific capacity of binder-free electrodes increased about twice, in comparison with the common electrodes due to the removal of the binder and the collector. The highest specific capacitance among the fabricated samples was obtained for the reinforced and activated sample with resorcinol/catalyst (R/C) ratio of 700, which was equal to 55.5 F/g. [ABSTRACT FROM AUTHOR]