Mitsuhiro Hibino

Electrochemical Properties of Nanostructured Amorphous, Sol-gel-Synthesized TiO2 / Acetylene Black Composite Electrodes

Amorphous titanium oxide was prepared by a sol-gel route employing Ti(IV) alkoxide as a starting agent. The average size of the primary particles was about 4 nm, and the Brunauer-Emmett-Teller specific surface area was 390 m 2 g -1 . Addition of acetylene black in synthesis allowed us to obtain the composite of titania and carbon materials. The composite materials could be galvanostaticly discharged and charged around 2 V vs. Li/Li + . After thermal treatment at 330°C the composite showed specific capacity above 125 mA h g -1 , even under large discharge current of 10 A g -1 . Based on the relationship between specific capacity and current density, the chemical diffusion coefficient of lithium was estimated to be 6 × 10 -12 cm 2 s -1 .

Metallic ruthenium incorporation in the porous structure of SBA-15 using a sonochemical method

Ultrasonic waves are employed for the first time to incorporate ruthenium into the pore structure of SBA-15. The resultant materials were analyzed by X-ray diffraction (XRD), nitrogen adsorption, transmission electron microscopy (TEM) and Raman measurements. Only microporous channels of SBA-15 are confirmed to be filled with ruthenium, leaving the mesopores unaffected. Therefore, high surface area and ordered structure are maintained after the incorporation of ruthenium nanoparticles in the porous structure of SBA-15.

Optimization of Sonochemical Synthesis Condition of Manganese Oxide/Acetylene Black Nanocomposite for High Power Lithium-Ion Batteries

In order to enhance the specific capacity of a sonochemically synthesized manganese oxide/carbon nanocomposite as the cathode material of a high-power lithium-ion battery, we optimized the synthesis conditions, such as the reaction temperature and specific surface area of the carbon. Through the reaction temperature control, the initial discharge capacity increased in keeping with the active material content and then decreased above a certain active material content. This degradation was caused by an increase in the active material content that was not able to specifically contact the carbon. In contrast, the use of a carbon with a higher specific surface area was found to lead to the higher specific capacity and suffered no capacity drop; the initial discharge capacities of 126 and 99.9 mAh g - 1 were obtained at current densities of 1 and 10 A g - 1 , respectively.

Sol-gel synthesis of porous crystalline TiO2-P2O5 oxide with thermal stability

Porous TiO 2 -P 2 O 5 oxide was synthesized by the sol-gel method in the presence of tri-block copolymer (EO) 2 0 (PO) 7 0 (EO) 2 0 (Pluronicl23) in queous solution. The TiO 2 nanocrystals with anatase structure precipitated in the as-synthesized TiO 2 -P 2 O 5 materials at 80 °C, considerably lower than that for traditional heat treatment in the solid state, which maintained a stable size of 3.6-4 nm upon calcinations below 500 °C. It is believed that P 2 O 5 glass phase prevents the coarsening of TiO 2 nanocrystals below 500 °C. The mixed oxide exhibited a specific surface area of 170-200 m 2 /g after calcining in the temperature range of 300-500 °C.