Materials Science Forum Vols. 486-487

Abstract: We prepared spinel-phase LiMn2O4 layer by using rf magnetron sputtering system. LiMn2O4 films were deposited at room temperature and then annealed at 750°C for crystallization to spinel type. In order to reduce the interface reaction such as Mn dissolution phenomenon during operation, we introduced SnOx (coating-layer) thin film. The SnOx films were deposited on LiMn2O4 films by rf magnetron sputtering system. A SnOx-coated LiMn2O4 film was more stable during the chargingdischarging reaction and maintained good cycle behavior at high temperature conditions of 55°C.

Abstract: In the polymer electrolyte, lots of salt have been studied and synthesized in many laboratories. In the previous our work[1,2], we found that the SiO2 (-7 nm, Degussa-Huls), which had the OH- and (CH3)3 surface groups, could help to enhance the ionic conductivity and the interfacial stability. We used as a plasticizer. It has the four CN groups at the end of chains. It was helpful to enhance the ionic conductivity, as respected. The ionic conductivity of the composite electrolytes was about 5.0ⅹ10-5 S/cm at room temperature. In addition, we conducted the charge/discharge test with LiMn2O4 at room temperature and 45 °C. The retention of 1st cycle to 100th cycle was 74 % at 45°C.

Abstract: SrZrO3 resistive oxides on Ag sheathed Bi(2223) tapes were prepared by the sol-gel and dip-coating method to investigate the effect of PVP content and thermal stage on microstructure of the films. Although film thickness rose with the addition of PVP, the amount of PVP was not effective to reduction in the crack density of the films. However, longer drying time at low temperature and shorter heat treatment time at 500oC were effective for controlling the microcracks of the SrZrO3 films, indicating that the microcracking of the films was governed primarily by the thermal stage.

Abstract: Kenaf bast, which is lignocellulosic fiber and environment friendly natural material, was tested for its ability to remove copper, nickel and zinc ions from aqueous solutions. The fiber was analyzed for xylose, lignin content, weight loss and dry volume, and extracted with diethyl ether, ethyl alcohol, hot water, or 1% sodium hydroxide to change physical and chemical characteristics of keanf bast. Diethyl ether and ethyl alcohol are organic solvents, which extract only extractives in the cell wall. The weight losses are less than 4.1%, the dry volumes increase up to 0.68 cm3/g, and the changes of lignin content are less than 0.6%. The differences of the heavy metal ions removal capacities are less than 0.05 mg/g, compared to those of control. Hot water and 1% sodium hydroxide remove cell wall components as well as extractives in the cell wall. In addition, during the extraction process the cell wall is swollen by the delamination of cell wall layers, xylose and lignin are exposed. The weight losses increases up to 24.0%, the dry volumes increase up to 1.20 cm3/g, and the changes of lignin content are less than 0.6%. The difference of the heavy metal ions removal capacities of kenaf bast increase up to 0.14 mg/g, and are much higher than those of diethyl ether and ethyl alcohol. The above results show that to increase the heavy metal ions removal capacities, the extraction chemicals may swell the cell wall more than water does and remove the cell wall components as well as extractives to change cell wall chemistry and architecture.

Abstract: “Glass wool” and “rock wool” had been used as sound absorbing materials over several decades because they have excellent sound absorbing properties as well as being very productive and economical. Unfortunately, they were found to be toxic because of flying glass whiskers. To replace glass wool and rock wool as the sound absorbing panels, the recycled glass powders with zeolite and Na2SiO were foamed, adding foaming agents such as NaOH and CaCO3 at different foaming temperatures and time in an electrical furnace. Recycled glass powders from crushed passenger car window were heated up to 720°C in an electrical furnace for an optimal foaming condition. The compressive strength of the foamed glasses was measured using a dynamic materials tester. On the basis of microstructure observation of the foamed glasses, the excellent sound absorbing materials was tried to be fabricated by measuring the sound absorbing coefficient of the foamed glass materials by adding various amounts of NaOH and water.

Abstract: To fabricate high efficiency, light-weight hydrogen storage materials in an economical way, a hydrogen induced mechanical alloying (HIMA) and an advanced melting/casting process were employed in a Mg-Ni hydride alloy system. The hydrogenation properties of the synthesized or/and cast specimen were evaluated with an automatic PCI (pressure-composition-isotherm) apparatus and TGA (thermo-gravimetric analysis). To produce Mg2NiHx intermetallics in an economical way, especially, Mg and Ni chips were mechanically alloyed under 2 MPa of hydrogen atmosphere by planetary ball milling. Adopting 66:1 BCR (ball to chips mass ratio) for HIMA process, fully hydrogenated alloys were obtained after 96 hrs of milling, resulting intotal hydrogen content of 2.25 mass%. The dehydriding temperature was found to be 453∼493 K. The composite phase obtained after 96 hrs of HIMA appeared to be composed of nanocrystalline and amorphous phases, of which structure was believed to enhance hydriding and dehydriding kinetics. The condition of BCR seemed to affect strongly the synthesis of the Mg2NiHx. In addition, the minimized Ni content specimens in Mg-Ni hydrides were successfully manufactured by Rotation- Cylinder method (RCM) without any heat treatments.

Abstract: Magnesium and Magnesium alloys have been studied as one of the good lightweight hydrogen storage materials, but the materials have strong difficulties in the fabrication process of mass production until now. The Rotation-Cylinder Method (RCM) has been developed to fabricate magnesium-based composites with moderate rotation under normal atmosphere. Inthis study, the Mg-TiNi hydrogen storage composites materials were manufactured by RCM and evaluated their hydrogenation properties by a Sieverts-type automatic pressure-composition-isotherm (PCI) apparatus at 523, 573 and 623K. The hydrogenation properties of Mg-TiNi composites depended on the behavior of TiNi reinforcements. The formation of Mg hydride, MgH2, on 4h milling samples of Mg-10mass% TiNi intermetallics hinted to the catalytic behavior of TiNi reinforcements. In addition, the dehydriding profile at 573K revealed the two steps of plateau pressure, which were affected by the existence of multi hydride phases.

Abstract: Magnesium and Magnesium alloys have been studied as one of the good lightweight hydrogen storage materials, but the materials have strong difficulties in the fabrication process of mass production until now. The Rotation-Cylinder Method (RCM) has been developed to fabricate magnesium-based composites with moderate rotation under normal atmosphere. In this study, the Mg-TiNi hydrogen storage composites materials were manufactured by RCM and evaluated their hydrogenation properties by a Sieverts-type automatic pressure-composition-isotherm (PCI) apparatus at 523, 573 and 623K. The hydrogenation properties of Mg-TiNi composites depended on the behavior of TiNi reinforcements. The formation of Mg hydride, MgH2, on 4h milling samples of Mg-10mass% TiNi intermetallics hinted to the catalytic behavior of TiNi reinforcements. In addition, the dehydriding profile at 573K revealed the two steps of plateau pressure, which were affected by the existence of multi hydride phases.

Abstract: The ionic conductivity and electrode-electrolyte interfacial stability have been measured for composite polymer electrolyte using nano-size alumina (Al2O3) with poly-ethylene oxide (PEO) polymer, and lithium tetrafluoroborate (LiBF4). The ionic conductivity of ball-milled PEO electrolyte was increased by Al2O3-filler-addition (BCPE) about 10 times greater than that without Al2O3 (BPE) over a range of 30°C to 80°C. The stability of resistance between electrode and electrolyte was significantly improved by the addition of Al2O3 filler during storage time. Cyclic performance of Li/BCPE/Li cell was superior to that of Li/BPE/Li cell.

Abstract: We investigated the effects of multi-walled carbon nanotubes (MWNT) and graphitic nanofibers (GNF) on the performance of sulfur electrode for the lithium/sulfur battery. MWNT and GNF were manufactured by a thermal chemical vapor deposition (CVD) method, and then they were added as an additive in the sulfur electrode. The added sulfur electrodes were composed of 60wt% elemental sulfur (Aldrich), 20wt% acetylene black, 5wt% MWNT or GNF, and 15wt% poly ethylene oxide (PEO) dissolved in acetonitrile. No-added sulfur electrodes were prepared by mixing 60wt% elemental sulfur, 25wt% acetylene black, and 15wt% PEO. The addition of MWNT and GNF was found to give good electrochemical effects in sulfur electrode.