Minami-rinkan, Japan
Minami-rinkan, Japan

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Yamada T.,Doshisha University | Saito M.,Doshisha University | Yodoya C.,Oike and Co. | Kamei A.,Oike and Co. | And 4 more authors.
ECS Transactions | Year: 2012

Pure Si thin flakes (Si Leaf Powder® (Si-LP)) of different thicknesses (50, 100, 200, 300 and 400 nm) were prepared, and their charge/discharge properties were investigated as anode materials for lithium ion batteries (LIBs). Thickness of the thin Si-LP (100 nm) changed reversibly during charging and discharging, while the expanded thickness upon charging was kept after fully discharged for the thick one (300 nm), indicating insufficient Li de-alloying at C/6 rate. The slower kinetics for the thicker Si-LPs was also confirmed by examination of the open circuit potential (OCP) and the rate capability. These suggested that Li atoms diffused easily within the thinner Si-LPs and the uniform Li distribution suppressed the physical stress due to the Li alloying and de-alloying, resulting a good cycleability. In addition, addition of vinylene carbonate (VC) in electrolyte reduced charge transfer resistance of the Li alloying/de-alloying reaction and much more improved the cycleability of Si-LPs. ©The Electrochemical Society.


Saito M.,Doshisha University | Yamada T.,Doshisha University | Yodoya C.,Oike and Co. | Kamei A.,Oike and Co. | And 4 more authors.
Solid State Ionics | Year: 2012

Pure Si thin flakes (Si Leaf Powder® (Si-LP)) of different thicknesses (50, 100, 200, 300 and 400 nm) were prepared, and their charge/discharge properties were investigated as negative electrode materials for lithium ion batteries (LIBs). High reversible capacity (2200-2500 mAh g - 1) and good capacity retention were obtained for thinner Si-LPs (50-200 nm), while thicker samples (300 and 400 nm) exhibited rapid capacity fade upon cycling at C/6. For the thinner flakes, agglomeration and large cracks were confirmed on the composite electrodes, but no pulverization of the flakes was observed. These data suggested that Li atoms diffused easily within the thinner Si-LPs and the uniformity of Li distribution suppressed the localized physical stress that caused by alloying and de-alloying. In addition, the addition of vinylene carbonate (VC) in the electrolyte was found to be quite effective for improving not only the cycleability, but also the rate-capability. The best performance was obtained for Si-LP (100 nm), which exhibited a superior cycleability (ca. 2300 mAh g - 1 at C/6 after 50 cycles) and a high rate capability (ca. 1400 mAh g - 1 at 12 C rate). © 2011 Elsevier B.V.


Okubo T.,Doshisha University | Saito M.,Doshisha University | Yodoya C.,Oike and Co. | Kamei A.,Oike and Co. | And 5 more authors.
Solid State Ionics | Year: 2014

To compensate the large irreversible capacity (Qirr), lithium was pre-doped to Si thin flakes (Si Leaf Powder® (Si-LP), thickness: 100 nm) for different times, and its effects on the charge/discharge characteristics such as reversible capacity, cycleability, and rate-capability were investigated in detail. The charge/discharge test results showed that a large initial Q irr of ca. 2300 mAh g- 1 for the Si-LP can be completely compensated by Li pre-doping, and a high capacity (> 2500 mAh g - 1) was obtained for pre-doped Si-LPs. The pre-doping did not cause any harmful effects on cycleability as long as lithium was uniformly pre-doped. The addition of vinylene carbonate to the electrolyte solution in the pre-doping and in the test cell greatly improved the cycleability, and a high discharge capacity of ca. 2300 mAh g- 1 was kept after 40 cycles. © 2013 Elsevier B.V.


Kinoshita K.,Tottori University | Okutani T.,Tottori University | Tanaka H.,Tottori University | Hinoki T.,Tottori University | And 5 more authors.
Solid-State Electronics | Year: 2011

Fabrication of flexible transparent resistive random access memory (FT-ReRAM) which consists of Ga doped ZnO (GZO) film not only as a memory layer but also as electrodes on the large Poly Ethylene Naphthalate sheet was attained by introducing RF plasma assist DC magnetron sputtering method. The averaged transmittance in the visible region (400-800 nm) was 66%. The memory effect was studied by using conducting atomic force microscope. It was suggested that the increase of Joule heating and oxygen vacancy density enhances memory effect, which is consistent with the redox model which has been proposed as the switching mechanism for conventional ReRAM. Stable and repeatable bi-polar resistive switching by application of the low voltage less than 2 V and low current less than 100 μA was confirmed in the FT-GZO-ReRAM. Reset switching, which is a switching from the low to the high resistance states, in GZO-ReRAM was confirmed to be smooth and continuous, which will enable a multilevel application. It was suggested that the smooth and continuous reset was brought about by Ga-doping. © 2010 Elsevier B.V.


Saito M.,Doshisha University | Nakai K.,Doshisha University | Yamada T.,Doshisha University | Takenaka T.,Oike and Co. | And 4 more authors.
Journal of Power Sources | Year: 2011

Pure Si platelets and Ni or Cu layer-laminated Si platelets with difference thickness were prepared, and their charge/discharge properties were examined in 1 M LiClO4/EC + DEC (1:1 by volume) as alternative negative electrode materials to graphite for Li-ion batteries. The shape of thin platelets and lamination with Ni layer are significantly effective to improve the cycleability in Li-Si alloy system by relieving the stress during the alloying/de-alloying processes, reinforcing the mechanical strength and reducing the Li+ ion diffusion length. Moreover, the first irreversible capacity is minimized by reduction of the amount of Ketjen Black (KB) in the composite electrode because of electrolyte decomposition on the surface of KB. Consequently, the Si/Ni/Si-LP30 (30/30/30 nm) composite electrode with 5 wt% KB also exhibits over 700 mAh g-1 even after 50 cycles in 1 M LiPF 6/EC + DEC (1:1). © 2011 Elsevier B.V. All rights reserved.


Saito M.,Doshisha University | Nakai K.,Doshisha University | Hagiwara M.,Doshisha University | Tasaka A.,Doshisha University | And 4 more authors.
ECS Transactions | Year: 2010

Two kinds of metal thin platelets (Leaf Powder®, Oike Co., Ltd.) based on Sn and Si were prepared, and their charge/discharge properties were investigated as alternative negative electrode materials to graphite for Li-ion batteries. One was simple metal platelets (M-LP, thickness: 100 nm) and the other was laminated platelets with an inactive Ni layer (M/Ni/M-LP, thickness: 30/30/30 nm). For both Sn and Si platelets, the shape of thin platelets effectively relieved the stress by volume expansion and shrinkage during the alloying and de-alloying processes, and improved their charge/discharge cycleabilities. Particularly, the Si platelets suppressed their agglomeration and pulverization, and much more remained the shapes than the Sn platelets. The lamination with the inactive Ni layer further improved the cycleability, though the specific capacity decreased by its presence. The alloying and de-alloying reaction with Li+ ion was substantially smooth, which was due to a decrease in the diffusion distance of Li+ ion by using the thin platelets. As a result, the Si/Ni/Si-LP exhibited a good capability over ca. 400 mAh g-1 up to 3C rate. ©The Electrochemical Society.


We report a numerical study to define moisture barrier performance of a multilayer barrier stack. Thin film electronic devices require a moisture barrier coating to prevent degradation of the devices. However a required barrier performance is an ultimate level which is indefinable value owing to uncertainness in the metrological control. Using diffusion simulation, we discuss validity of barrier performance in the conventional definition of water vapor permeation rate and the actuality of water permeation into an encapsulated volume. The diffusion simulation predicted that the multilayer barrier-stack shows a window of permeation rate related to environmental moisture, a determinant for measureable limit, detail of moisture diffusion in an encapsulated system. An integrative evaluation method suggested that the barrier performance can be consistently defined from total amount of water permeation. The simulation results were obtained from the calculation of multilayer numerical components which were determined by data fitting with measured data, showed 1gm-2 of total permeation in 3years with 3 dyad barrier-stacks. copy; 2014 Elsevier B.V.


Kinoshtia K.,Tottori University | Okutani T.,Tottori University | Tanaka H.,Tottori University | Hinoki T.,Tottori University | And 4 more authors.
Applied Physics Letters | Year: 2010

A hypothesis based on the model that explains the resistance change effect of resistive random access memory by redox reaction is proposed. This hypothesis leads to the conclusion that the relationship between the polarity of the applied bias voltage and the resultant resistance change in p -type semiconductors is opposite to that for n -type semiconductors. The bias polarity dependence of the resultant resistance change in ZnO and Ga-doped ZnO (GZO), which are n -type semiconductors, and that in NiO, which is a p -type semiconductor, were investigated using conducting atomic force microscopy. Opposite bias polarity was confirmed to induce GZO and NiO into the same resistance state, which is consistent with the hypothesis. © 2010 American Institute of Physics.


Muro K.,OIKE and Co. | Watanabe M.,Osaka Municipal Technical Research Institute | Tamai T.,Osaka Municipal Technical Research Institute | Yazawa K.,OIKE and Co. | And 2 more authors.
RSC Advances | Year: 2016

Conductive polymer consisting of poly(3,4-ethylenedioxythiophene)/cross-linked poly(p-styrenesulfonate) (PEDOT/CL-PSS) particles was synthesized, and its dispersion and film properties were evaluated. CL-PSS was synthesized by sulfonation of poly(styrene-co-divinylbenzene) prepared by emulsion polymerization, and PEDOT/CL-PSS was synthesized by oxidative polymerization of EDOT in the presence of CL-PSS particles. The dispersion of PEDOT/CL-PSS exhibited lower viscosity than that of the usual PEDOT/PSS, enabling the highly concentrated dispersion of the conductive polymer in water. The electrostabilities of the PEDOT/CL-PSS film against heat and humidity were significantly improved by the cross-linkage, although the conductivity decreased with the increase of crosslink density. PEDOT/CL-PSS was miscible with PEDOT/PSS and could be used as a surface roughness-controlling agent for PEDOT/PSS film. © The Royal Society of Chemistry 2016.


Okunishi T.,OIKE and Co. | Sato N.,OIKE and Co. | Yazawa K.,OIKE and Co.
Journal of Physics: Conference Series | Year: 2013

In order to protect surface from damages, the high pencil hardness and the high abrasion resistance are required for the hard coat layers on polyethylene telephthalate (PET) films for the application of touch panel surface. We have already found that the UV-curing-hard-coat-polymer (UHP) coated PET films show the poor abrasion resistance, while they have the high pencil hardness. It reveals that the abrasion resistance of hard coat layers of the UHP is not simply dependent on the pencil hardness. In this work, we have studied to improve the abrasion resistance of SiOC films as hard coat layers, which were formed by PE-CVD process on UHP coated PET. The abrasion resistance was evaluated by Taber abrasion test. PE-CVD hard coat layers which formed on UHP coater PET films have showed the better abrasion resistance and have the possibility of substitution to the thin glass sheets for touch panel application.

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