Advanced Materials Research Vols. 1070-1072

Abstract: Lead-acid battery has perfect characteristics, such as good performance, rich raw materials and low prices, it plays an important role as starting power and auxiliary power in vehicles, Because of inadequate understanding internal active material in physical or chemistry reaction in charging process or technical conditions of limit ,the charging methods mainly contents the constant voltage ,constant voltage the current limit, constant current .These methods fail to damages such as overcharging ,short-charging, gas chromatography and high electrolyte temperature. So, this paper analyzes concentration polarization and electrochemical polarization in fast charging based on the MAS theorems. However, pulse discharge technology can change the concentration of ions near the electrode, which speeds up the electrochemical reaction rate and increase the energy into the chemical energy efficiency.

Abstract: Hierarchically porous carbon (HPC)/MnO₂ nanocomposites were fabricated for asymmetric supercapacitor applications. The microstructures of HPC/MnO₂ nanocomposites were characterized by X-ray diffraction and scanning electron microscopy. The asymmetric supercapacitor consisting of a HPC/MnO₂ cathode and a HPC anode shows an excellent performance with energy density and power density of 23.8 Wh kg^-1 and 12.5 kW kg^-1, respectively. In addition, the asymmetric supercapacitor exhibits an excellent cycle life with 91% retention of capacitance after 1000 cycles.

Abstract: Two kinds of mesoporous carbons (MPC) with three-dimensional (3D) body-centered cubic (Imm) and 2D hexagonal symmetry (p6m) were synthesized by using triblock copolymer PEO-PPO-PEO (F127) and diblock copolymer polydimethylsiloxane-poly (ethylene oxide) (PDMS-PEO) as co-templates and were further activated by nitric acid oxidation. The electrochemical performances of MPCs and acid-modified MPCs (H-MPCs) electrodes were investigated. After nitric acid modification, the capacitive performances of MPCs were obviously improved. The acid-modified sample with 2D p6m symmetry (H-2D-MPC) exhibited the highest specific capacitance of 237.1 F g^-1 in 6 M KOH at the current density of 1 A g^-1 and could be a potential candidate for supercapacitors.

Abstract: Due to their excellent properties, carbon nanotubes (CNTs) have the potential to be applied as functional elements for nanoelectronics, nanoelectromechanical systems, new energy, sensors, and others. One precondition for many of these applications is to assemble CNTs into devices and the number and position of assembled CNTs usually need to be controlled. The process factors for CNT assembly by dielectrophoresis (DEP), which include the magnitude of the applied voltage, the concentration of the CNT suspension, the duration of the electric field, and the geometry of the CNTs, and the shape of the electrodes, have great influence on the assembly results. Some techniques based on DEP, such as those adding floating electrodes, optically induced DEP (ODEP) and using hydrodynamic force, can realize precise positioning of CNTs. This paper introduces the factors and techniques which influence the number and position of assembled CNTs. The research intends to provide help for the application of CNTs in nanoelectronics.

Abstract: With the development of the portable electronics industry, the need for more efficient power sources has been enlarged. Lithium-ion batteries are able to deliver high energy densities, high capacity and long cycle life at reasonable costs among competing energy storage technologies. The major goal of this paper is to introduce the promising Li-rich cathode material xLi₂MnO₃·(1-x) LiMO₂(M=Ni, Co, Mn...), which owns enhanced energy and power density, high energy efficiency, superior rate capability and excellent cycling stability due to different modification methods.

Abstract: In order to reduce the emission and realize the sustainable development in aviation industry, looking for alternative fuel as kerosene has become more and more important. Hydrogen is regarded as one of the most promising alternative fuels. In our study RP-3 kerosene with hydrogen addition is used as the alternative kerosene. A RP-3 kerosene surrogate includes n-decane, toluene and propyl cyclohexane (volume fraction is 0.65/0.1/0.25) was chosen and the ignition delay times are calculated in CHEMKIN-PRO, it is found that hydrogen addition can shorten ignition delay.

Abstract: Sulfurized polyacrylonitrile was well known for its excellent electrochemical performance. In this work, a kind of gel polymer electrolyte with PMMA as polymer matrix was prepared through in situ thermal initiated polymerization in this work. The interactions between polymer and traditional carbonate electrolyte were studied by IR. Its electrochemical performance in Li/SPAN batteries was investigated in detail, using LSV, CV, EIS et al. The results show that high ionic conductivity was achieved, with a value of 4.2 mS cm^-1 at 30^◦C when the content of PMMA was 15%. A reversible capacity of 975.3 mAh g^-1 could be maintained after 50 cycles.

Abstract: Gelled crude oil sticking on the wall during hydraulic suspension transportation will lead to large transport resistance and high energy consumption, such serious cases can cause pipeline plugging. In order to promote the technology of hydraulic suspension transportation of gelled crude oil, this paper built the text system of oil sticking on the wall, studied on effects of flushing pipe which oil sticking on with water directly, analyzed whether gelled crude oil sticking on the wall is uniform, the quantity of water for flushing , time for flushing etc the effects on flushing. Experimental results showes that, the effect of a few gelled crude oil particles sticking on the wall, being rinsed by cool water is good; the effect of flushing non-uniform sticking on the wall is better than uniform with large one. When the diameter of 53mm pipe’s wall adhesive 5mm thick (135g) of gelled crude oil (freezing point is 38°C), using the flow of 3.7 to 5.7 m³/h and water of 18°C to flush, the effects of flushing the uniform oil tube which oil stick on is between 2.8 to 5.9%, the effects of flushing the non-uniform one is between 9.5 to 23.3%; when the flow of tap water increased from 3.7 to 5.7m³/h, the quantity of flushed off oil uniform and non-uniform sticking on the wall was increased by 2.1% and 5.8%. For different types of flushing experiment, the effect is better in front 15min. Over time, flushing effect had gradually weakened, and the amount of flush out oil wasn’t increased significantly when time increased to 45min later.

Abstract: A method for judging the gray property of flames based on spectral analysis and the two-color method for determining the temperature and emissivity of flame has been demonstrated. A calibrated spectrometer system was used for the data acquisition of the radiation intensity profile of a flame over a range of wavelengths (200 – 1100 nm). The wavelength range that meets the gray body assumption, in which the emissivity can be assumed as a constant, can be determined from the emissivity profile obtained by spectral analysis and the two-color method. Then the temperature and emissivity of the flame and their relative mean square deviations were calculated within that range. Experiments were conducted on pulverized coal-fired flames in a commercial 300MW boiler furnace. The results show that the coal-fired flame can be assumed as gray body between 500 nm and 1000 nm, and the temperature and emissivity calculation results of coal-fired flames are found to be in reasonable agreement with results using other methods from the literature.

Abstract: Drying of lignite alters the physical and chemical structure of coal, and influences the oxygen transport on the low temperature oxidation process. This paper provides a comprehensive overview on low-temperature oxidation of lignite and its dried products, including oxygen transport during the oxidation process, changes of physical structure and chemical compositions occurring at the drying process and its effects on the oxygen transport, and restraint of dried lignite oxidation.