著者

宮代 一 小林 陽 中村 龍哉 関 志朗 三田 裕一 宇佐美 章

出版者

The Electrochemical Society of Japan

雑誌

Electrochemistry (ISSN:13443542)

巻号頁・発行日

vol.74, no.4, pp.321-325, 2006-04-05 (Released:2012-03-20)

参考文献数

23

被引用文献数

2 4

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Olivine structured LiFePO4 cathode is the promising cathode active material for lithium secondary batteries due to its low cost and quite excellent reversibility. On the other hand, lithium polymer secondary batteries (LPBs) have been studied for the purpose of large-scaled batteries (for example, electric power load leveling). In this study, we prepared LPBs using the LiFePO4 cathode. By measuring the charge-discharge properties and electrochemical impedance spectroscopy, basic properties were investigated compared with the LPBs using the 4V-class LiCoO2 cathode.

著者

中村 龍哉 松井 裕樹 山田 義博 田渕 光春 小林 陽

出版者

Japan Society of Powder and Powder Metallurgy

雑誌

粉体および粉末冶金 (ISSN:05328799)

巻号頁・発行日

vol.57, no.11, pp.725-728, 2010-11-15

参考文献数

17

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Cathode using the olivine particles was subjected to an open-circuit voltage measurement under the relaxation condition of 24 h at each SOC and DOD states. The electrochemical reaction in the LiFePO<SUB>4</SUB> cathode was composed of a large plateau around 3.45 V with sloped regions nearby for both the fully charged and discharged states. It was found that the potential profile in the sloped regions exhibited a hysteresis. Furthermore, both sloped regions became narrower when the operating temperature was raised from 30 to 60°C. Furthermore, it was found that the apparent diffusion coefficient of Li<SUP>+</SUP> ions in the sloped regions was much smaller than that in the plateau region. These facts implied that the obtained profiles were not in an equilibrium state with a quasi-OCV profile than the real one, and that the potential relaxation in the sloped regions took an extremely long time.

著者

島 裕也 中村 龍哉 松井 裕樹 山田 義博 宮内 啓成 橋本 聡司 阿部 一雄

出版者

Japan Society of Powder and Powder Metallurgy

雑誌

粉体および粉末冶金 (ISSN:05328799)

巻号頁・発行日

vol.57, no.11, pp.729-733, 2010-11-15

参考文献数

13

被引用文献数

1

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LiFePO<SUB>4</SUB>/C composite particles were prepared by gas-solid phase reaction. The reaction temperature had a detrimental effect on the purity of the composite particles. The suitable temperature was around 650°C, above and below which ferromagnetic impurities were found. The retention time influenced only the carbon deposition amount, but the excess amount of carbon caused the degradation of the electrochemical performance. The specimen prepared at the optimum conditions exhibited superior performances in both rate capability and cycle stability as well as less impedance growth during the cycling.