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32 results on '"Nakura, Kensuke"'

27. Capacity Fading of Lithium-Ion Cells Having Li[Li1/3Ti5/3]O4 (LTO)-Negative Electrodes for the First- and Second-Generation 12 V Lead-Free Batteries.

Author

Lina Wang, Nakura, Kensuke, Imazaki, Mitsuyasu, Kakizaki, Narumi, Ariyoshi, Kingo, and Ohzuku, Tsutomu

Subjects
ELECTROCHEMICAL research, LITHIUM-ion batteries, ELECTRODES, ELECTRIC capacity, ELECTROSTATICS
Abstract

Lithium-ion cells consisting of Li[Li1/3Ti5/3]O4 (LTO) and Li[Li0.1Al0.1Mn1.8]O4 (LAMO) or Li[Ni½Mn3/2]O4 (LiNiMO) were examined at currents higher than 1 mA cm-2 at room temperature. Capacity fading was observed for both LTO/LAMO and LTO/LiNiMO cells during the continuous charge and discharge at 1, 2, and 4 mA cm-2 when a microporous membrane usually used so far was applied. In order to understand the capacity fading, Li/LAMO and Li/LTO cells together with zero-volt lithium-ion cells consisting of LTO or LAMO were fabricated and examined. Among these cells, the rechargeable capacity of a zero-volt lithium-ion cell of LTO with a microporous membrane faded cycle by cycle, while the other cells did not show such obvious capacity fading. From these results, a possible source of capacity fading was discussed in terms of a mass transport problem due to the "zero-strain" insertion electrode combined with a microporous membrane. A solution of the problem is also given in such a way that a non-woven cloth is substituted for the microporous membrane as a separator in LTO/LAMO and LTO/LiNiMO cells for the first- and second-generation 12 V lead-free batteries, respectively. [ABSTRACT FROM AUTHOR]

Published
2012
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28. Prevention of the Micro Cracks Generation in LiNiCoAlO2 Cathode by the Restriction of ?DOD

Author

Watanabe, Shoichiro, Hosokawa, Takashi, Morigaki, ichi, Kinoshita, Masahiro, and Nakura, Kensuke

Abstract

Lithium Nickel-Cobalt-Aluminum oxide cathode material taking out from lithium-ion cell after restricted DOD (Depth of Discharge) range cycle was analyzed by X-ray diffraction (XRD), cross section scanning electron microscope (SEM), transmission electron microscope (TEM) and scanning transmission electron energy-loss spectroscopy (STEM-EELS). Many of the micro cracks were observed in the cathode particles after 0-100% DOD range cycle. On the other hand, that was little confirmed regardless of the operated voltage area when cycled DOD range was restricted. After generation of the micro cracks, the crystal structure at the surface of primary particles which was faced on them was immediately changed to rock salt like structure. The cycle performance under the conditions of restriction of DDOD showed superior results of 3000 cycles even at 50deg.

Published
2012

29. Capacity Fading of Lithium-Ion Cells Having Li[Li1/3Ti5/3]O4 (LTO)-Negative Electrodes for the First- and Second-Generation 12 V Lead-Free Batteries

Author

Wang, Lina, Nakura, Kensuke, Imazaki, Mitsuyasu, Kakizaki, Narumi, Ariyoshi, Kingo, and Ohzuku, Tsutomu

Abstract

Lithium-ion cells consisting of Li[Li1/3Ti5/3]O4 (LTO) and Li[Li0.1Al0.1Mn1.8]O4 (LAMO) or Li[Ni1/2Mn3/2]O4 (LiNiMO) were examined at currents higher than 1 mA cm[?]2 at room temperature. Capacity fading was observed for both LTO/LAMO and LTO/LiNiMO cells during the continuous charge and discharge at 1, 2, and 4 mA cm[?]2 when a microporous membrane usually used so far was applied. In order to understand the capacity fading, Li/LAMO and Li/LTO cells together with zero-volt lithium-ion cells consisting of LTO or LAMO were fabricated and examined. Among these cells, the rechargeable capacity of a zero-volt lithium-ion cell of LTO with a microporous membrane faded cycle by cycle, while the other cells did not show such obvious capacity fading. From these results, a possible source of capacity fading was discussed in terms of a mass transport problem due to the "zero-strain" insertion electrode combined with a microporous membrane. A solution of the problem is also given in such a way that a non-woven cloth is substituted for the microporous membrane as a separator in LTO/LAMO and LTO/LiNiMO cells for the first- and second-generation 12 V lead-free batteries, respectively.

Published
2012

31. Prevention of the Micro Cracks Generation in LiNiCoAlO2Cathode by the Restriction of ΔDOD

Author

Watanabe, Shoichiro, Hosokawa, Takashi, Morigaki, Ken'ichi, Kinoshita, Masahiro, and Nakura, Kensuke

Abstract

Lithium Nickel-Cobalt-Aluminum oxide cathode material taking out from lithium-ion cell after restricted DOD (Depth of Discharge) range cycle was analyzed by X-ray diffraction (XRD), cross section scanning electron microscope (SEM), transmission electron microscope (TEM) and scanning transmission electron energy-loss spectroscopy (STEM-EELS). Many of the micro cracks were observed in the cathode particles after 0-100% DOD range cycle. On the other hand, that was little confirmed regardless of the operated voltage area when cycled DOD range was restricted. After generation of the micro cracks, the crystal structure at the surface of primary particles which was faced on them was immediately changed to rock salt like structure. The cycle performance under the conditions of restriction of ΔDOD showed superior results of 3000 cycles even at 50°.

Published
2012
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32. Capacity fading of LiAl y Ni1−x−y Co x O2 cathode for lithium-ion batteries during accelerated calendar and cycle life tests (effect of depth of discharge in charge–discharge cycling on the suppression of the micro-crack generation of LiAl y Ni1−x−y Co x O2 particle).

Author

Watanabe, Shoichiro, Kinoshita, Masahiro, Hosokawa, Takashi, Morigaki, Kenichi, and Nakura, Kensuke

Subjects
*LITHIUM compounds, *LITHIUM-ion batteries, *CATHODES, *SERVICE life, *X-ray photoelectron spectroscopy, *GRAPHITE, *ELECTRIC potential
Abstract

Cycle performance of a LiAl0.10Ni0.76Co0.14O2 (NCA) cathode/graphite cell closely depended on the range of depth of discharge in charge–discharge processes (ΔDOD). When ΔDOD was 10–70%, cycle performance at 25 °C was maintained even at 60 °C. Deterioration phenomena were analyzed by electrochemical method, X-ray photoelectron spectroscopy (XPS), X-ray diffractometry (XRD), and micro-cracks in NCA particles were analyzed with cross-sectional views by scanning electron microscopy (SEM). Many micro-cracks were observed only after a 0–100% DOD region cycle test. Cycle tests in several restricted ΔDOD conditions showed that the deterioration was closely related to not the upper and lower limits of DOD or operation voltage but the width of ΔDOD. [ABSTRACT FROM AUTHOR]

Published
2014
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