Phase diagrams of binary mixtures of alkali bis(trifluoromethylsulfonyl)amides have been constructed and their eutectic compositions and temperatures have been determined. It has been revealed that the molten salt electrolytes having the melting points in the intermediate temperature range (373 to 473) K are easily formed by simple mixing of two kinds of single alkali bis(trifluoromethylsulfonyl)amides salts. The 1:1 or 3:1 double salt is occasionally formed for some binary systems.

Graphene, a single layer of graphite, has recently attracted a large amount of attention because of its extremely high electronic and thermal properties, as many nanoscale materials are based on individual graphene. Graphene oxide (GO), which is the intermediate during the chemical processing of graphene, consists of graphene functionalized with oxygen-containing functional groups that imparts the desirable solution-processability to the neat graphene. Herein, poly(vinyl alcohol) (PVA), a hydrophilic polymer, was selected as the matrix, and PVA/GO nanocomposites were prepared by a simple and environment friendly process using water as the proceeding medium. In the PVA matrix, GO was exfoliated and nanodispersed. We found that the nanocomposites constructed by the incorporation of GO up to 1% by weight possess remarkable properties, such as significantly high mechanical and thermal properties. These excellent reinforcement effects were achieved not only by the rigid structure and high aspect ratio of the exfoliated GO but also by the strong interaction between PVA and GO. Furthermore, owing to the sheet-like structure of GO, the barrier properties of the nanocomposites were found to be dramatically increased.

Densities, viscosities and ionic conductivities of single salts and the binary eutectic mixtures of alkali bis(trifluoromethylsulfonyl)amides, MTFSAs (M = Li, Na, K, Rb, Cs), were measured in the temperature range of 413-573 K. Cyclic voltammetry revealed that the binary eutectic melts have wide electrochemical windows of 5.0-6.0 V. It was found that alkali metals reversibly deposit on a nickel electrode at the cathode limit potentials. The order of the deposition potential was determined to be Na > Li > (K, Rb, Cs).

Thermal properties of alkali bis(fluorosulfonyl)amides, MFSI (M = Li, Na, K, Rb, Cs), have been investigated. Binary phase diagrams of LiFSI-KFSI and NaFSI-KFSI systems have been constructed. Eutectic point for LiFSI-KFSI is 338 K at (xLi, xK) = (0.45, 0.55) and, that for NaFSI-KFSI is 330 K at (xNa, xK) = (0.45, 0.55). The electrochemical window of the eutectic LiFSI-KFSI is as wide as 6.0 V at 348 K with the cathode limit being lithium metal deposition. The electrochemical window of the eutectic NaFSI-KFSI is 5.0 V at 340 K with sodium metal deposition at the cathode limit. These new inorganic ionic liquids are highly promising for various electrochemical applications.

No abstract

No abstract

As the finalization of the hydrogen experiment towards the deuterium phase, the exploration of the best performance of the hydrogen plasma was intensively performed in the Large Helical Device (LHD). High ion and electron temperatures, Ti, Te, of more than 6 keV were simultaneously achieved by superimposing the high power electron cyclotron resonance heating (ECH) on the neutral beam injection (NBI) heated plasma. Although flattening of the ion temperature profile in the core region was observed during the discharges, one could avoid the degradation by increasing the electron density. Another key parameter to present plasma performance is an averaged beta value . The high regime around 4 % was extended to an order of magnitude lower than the earlier collisional regime. Impurity behaviour in hydrogen discharges with NBI heating was also classified with the wide range of edge plasma parameters. Existence of no impurity accumulation regime where the high performance plasma is maintained with high power heating > 10 MW was identified. Wide parameter scan experiments suggest that the toroidal rotation and the turbulence are the candidates for expelling impurities from the core region.

The physicochemical properties of molten alkali bis(trifluoromethylsulfonyl)amide, MTFSI (M = Li, K, Cs), mixture (xLiTFSI = 0.20, xKTFSI = 0.10, xCsTFSI = 0.70) were studied to develop a new rechargeable lithium battery operating at intermediate temperature (100-200°C). The viscosity and ionic conductivity of this melt at 150°C are 87.2 cP and 14.2 mS cm −1 , respectively. The cyclic voltammetry revealed that the electrochemical window at 150°C is as wide as 5.0 V, and that the electrochemical deposition/dissolution of lithium metal occurs reversibly at the 2 cathode limit. A Li/MTFSI (M = Li, K, Cs)/LiFePO4 cell showed an excellent cycle performance at a constant current rate of C/10 at 150°C; 95% of the initial discharge capacity was maintained after 50 cycles. Except for the initial few cycles, the coulombic efficiencies were approximately 100% for all the cycles, indicating the stabilities of the molten MTFSI mixture and all the electrode materials.