Online ISSN : 2186-2451
Print ISSN : 1344-3542
ISSN-L : 1344-3542
Volume 73 , Issue 10
Showing 1-12 articles out of 12 articles from the selected issue
  • Yun-S. LEE, Sung-J. CHO, Yang-K. SUN, Koichi KOBAYAKAWA, Yuichi SATO
    2005 Volume 73 Issue 10 Pages 874-882
    Published: October 05, 2005
    Released: June 01, 2019

    Two lithium iron oxides have been synthesized at low temperatures by the conventional solid-state method. Orthorhombic LiFeO2 has been synthesized using LiOH and γ-FeOOH at 150°C was composed of orthorhombic LiFeO2 and small amount of spinel LiFe5O8 phases. A Li/LiFeO2 cell showed not only a fairly high initial discharge capacity of over 150 mAh g−1 but also a good cycle retention rate at room temperature. It was found that the orthorhombic phase of the LiFeO2 underwent a structural change to the LiFe5O8 spinel phase in the first cycle. Especially, it showed a severe structural change during the first discharge process, which might be the main reason for the capacity loss of the Li/LiFeO2 system. An amorphous-like LixFeyOz has been synthesized using LiOH and α-FeOOH at 200°C consisted of three kinds of structures, LiFe5O8, Li5FeO4, and a trace of cubic α-LiFeO2 A Li/LixFeyOz cell showed a very high initial discharge capacity (215 mAh g−l) as well as an excellent cycle retention rate (95%) from the 11th to the 50th cycle. It was found that LixFeyOz material was transformed into the spinel LiFe5O8 and tetragonal β-LiFeO2 phases after long-term cycling.

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Technological Report
  • Kohjiro HARA, Sanekazu IGARI, Shingo TAKANO, Gaku FUJIHASHI
    2005 Volume 73 Issue 10 Pages 887-896
    Published: October 05, 2005
    Released: June 01, 2019

    Photovoltaic performance of dye-sensitized solar cells (DSSCs) based on a nanocrystalline TiO2 electrode have been measured in terms of I-V characteristics under standard AM 1.5 G irradiation and spectral response (incident photon to current conversion efficiency, IPCE) of the cells. The performance of DSSCs depended remarkably on the measurement conditions. It has been observed that the conventional characterization conditions for photovoltaic performance of crystalline and amorphus silicon solar cells are not suitable for characterization of DSSCs. In this paper, we suggest suitable characterization conditions, which are to be standard measurement conditions in the near future, for the photovoltaic performance of DSSCs.

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  • Hideo YOSHINAGA, Junji ASAI, Masashi WADA, Kouichi YAMAMOTO, Tetsuo SA ...
    2005 Volume 73 Issue 10 Pages 897-899
    Published: October 05, 2005
    Released: June 01, 2019

    We have succeeded in producing a V-Sn alloy thin film as an anode material for lithium-ion batteries using sputtering method. The V-Sn alloy target was prepared by thermic process. The obtained V-Sn alloy targets are mainly composed of V2Sn3 phase containing tin impurity, but these alloy thin films are composed of V-Sn amorphous phase and Sn phase. The half-cell tests revealed that the cycle performance of the V-Sn thin film electrode was significantly improved by the annealing the target. The V-Sn thin film electrode showed an initial rechargeable capacity of 700 Ah /kg, which was reduced to 558 Ah /kg even after 300 cycles.

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  • Daisuke TASHIMA, Kenji KUROSAWATSU, Youl-Moon SUNG, Masahisa OTSUBO, C ...
    2005 Volume 73 Issue 10 Pages 900-902
    Published: October 05, 2005
    Released: June 01, 2019

    Electric double layer capacitors were prepared using acetylene black and ketjen black as electrode materials with different types of pore structures. From the results of cyclic voltammetry, it is clear that EDLC based on ketjen black has better capacitive behavior. The specific capacitance of about 55.8 F/g using the polarizable electrodes with ketjen black was obtained. Moreover, space charge distributions of EDLC based on polarizable electrodes were investigated by a pulsed electro acoustic method. The polarizable electrode with ketjen black has higher charge density. It can be found that ketjen black plays an essential role in the improvement of capacitance in EDLC.

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