No abstract

No abstract

No abstract

The face-centered cubic (fcc) type magnesium-zirconium hydride (Mg0.82Zr0.18Hx) was synthesized by means of the ultrahigh pressure (UHP) technique, which could generate 8 GPa of hydrogen pressure. The differential scanning calorimeter (DSC) measurements indicated that the fcc phase exhibited reversible hydrogen releasing and restoring properties under 0.5 MPa of hydrogen pressure. On the pressure-composition isotherms, the released and restored hydrogen capacities were estimated to be 3 approximately 3.5 wt %. The Rietveld analysis for synchrotron X-ray diffraction (XRD) data showed that the fcc phase had around 70 wt % mass fraction and was preserved without decomposition during hydrogen releasing and restoring cycles.

A carbon fiber-type Cu-Sn negative electrode was prepared for use in the Li-ion battery. The Cu 6 Sn 5 alloy layer was formed on the carbon fibers by electroplating methods. After heat-treatment at 400 • C, the as-plated Cu 6 Sn 5 was transformed into multiple phases composed of Cu 3 Sn, SnO 2 and Cu 6 Sn 5 phases. The resultant Cu-Sn-400 fiber-type electrode exhibited better cycle-life and high-rate performances than the Cu 6 Sn 5 alloy based one. Even after 300 cycles, 72% of the initial discharge capacity was maintained. The phase compositions of the charged and discharged electrodes were investigated by a synchrotron XRD analysis.For more than two decades, lithium-ion (Li-ion) batteries have been widely used as the power source of consumer electric devices, such as mobile phones, laptop computers and power tools. The research and development of this battery is now focused on applications in a hybrid electric vehicle (HEV) and electric vehicle (EV) because of its superior high energy-density. 1,2 Total energy management, which involves the energy storage and supply between a plug-in hybrid electric vehicle (PHEV) with a Li-ion battery and the power grid, is examined and introduced. 3,4 Furthermore, the demand of large-scale battery systems capable of delivering several hundreds of kWhs is gradually being extended to industrial applications, such as a battery-driven train, a wayside energy storage system for railways and stabilization of natural power generation. Verification tests have been carried out using the Li-ion battery 5-7 as well as a nickel-metal hydride (Ni-MH) one. [8][9][10] Meanwhile, enhancements in the battery performances, such as power, cycle-life, safety and costs, are the crucial issues for Li-ion batteries in order to realize its widespread use in industrial applications.At present, a copper(Cu) foil is typically used for the negative current collectors of the Li-ion battery. A slurry containing the activematerial powder is coated on a Cu foil substrate. To improve the energy density and cycle-life performance of the Li-ion battery, Ni-foam substrates have been used. 11 Moreover, a proposed three-dimensional (3-D) micro-battery design, in which the number of electrodes is configured in a non-planar geometry, offers a solution for highrate capability due to the effectively increased electrode/electrolyte interface. 12,13 These advanced 3D electrode configurations would lead to enhanced battery performances.Recently, fiber-type Ni(OH) 2 electrodes were developed for the Ni-MH battery using the electrodeposition method. 14,15 In these electrodes, individual carbon fibers were coated with a Ni(OH) 2 layer. The test cell using the fiber-type electrodes exhibited better highrate and cycle-life performances than that of the conventional one. In order to realize the 3D micro-battery, both the positive and negative electrodes would be expected to change to fiber-type electrodes. However, for the Ni-MH battery, it would be very difficult to prepare a fiber-type negative alloy electrode using the ele...